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UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION Vienna International Centre, P.O. Box 300, 1400 Vienna, Austria Tel: (+43-1) 26026-0 · www.unido.org · [email protected] y We regret that borne of the pages in the microfiche copy of this report may not be up to the proper legibility standards,even though the best possible copy was used for preparing the master fiche DSM*) LMMTID UNI00/I00.1ff1 UMITtDMATIOMt 14 An»«» MOIMTfllAL MVILOMMNT OHOANIZATION f NOLIM

TECHNOLOGICAL PROFUS ON THE HON AND STEEL MDUSTKY*

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These four technological profiles, on a world iron oree survey including benefici at ion, sintering and pelletiaing, iron making, steel making and steel casting including continuous casting, have been prepared for the UNIDO Industrial and Technological Information Bank (INTIB), which is a component of the UNIDO programme on the development and transfer of technology.

INTIB is a pilot operation which began in July 1977 for a period of 18 months. During this pilot phase it is being concentrated on four industrial sectors: iron and steel, fertilizers, agro-industries, and agricultural machinery and implements. Each of these sectors has priority in ( ther UNIDO endeavours: sectoral studies, consultations, eventual negotiations and technical assistance projects.

The concept of INTIB has its roots in the Lima Declaration and Plan of Action, adopted at the Second General Conference of UNIDO in I975, and in various United Nations General Assembly resolutions, all envisaging such a service as a prerequiaite to, and an instrument for, the transfer, development and adaptation of appropriate technologies.

Vit* the tar^etted expansion of industry in developing countries from a 7 per cent sharp of global industrial output at the time of the Lima Conference to 25 per cent in the yrrr 2000 - an objective set by the Conference - adequate information on new investments at the decision- maker level is crucial. The same is true for those advising the decision-makers: national industrial information centres, technology development institutes, investment banks and so on.

The novel character of INTIB, as compared witb information services previously rendered by UNIDO, consists of addressing itself to the technology selection process at the stage preceding itB acquisition and operation, and of offering advisory services beyond the provision of information.

INTIB draws upon services available in the Industrial Information Section, where it is housed, but also relies on the expertise of specialist staff in the Industrial Operations Division and from commissioned experts for the processing of information material obtained from sources within and outside UNIDO relevant to the technology selection process. The outcome of this effort takes the form of information supplied in anticipation of

The target users of INTIB include ministries of industry, planning and industrial development, multi-purpose technological institutions, transfer of technology centres and registries, and so on. The listing, however, is not exhaustive. The intention is to serve all those who can be identified as having genuine technology-selection responsibilities and problems, whether in an advisory role or decision-making capacity, in each of the four priority industrial sectors selected for this pilot phase.

Purther information about INTIB and its related activities can be had on request by writing to the Chief, Industrial Information Seotion, UNIDO, Co-ordinator of INTIB, P.O. box 707, A-1011 Vienna, *»stria.

These technological profiles were prepared by Mr. Ct.P. Mathur, acting •s a consultant to UNIDO.

- i -

COFTINTI

8«. No. Pojo lío.

1. Iron Oro Minorólo 4 t. Major Bopoaito 5 }. production and Rooorvoo • 4. Bonoficiation Motaodo W 4.1 Bonofioiation Praotieoo M J. Afclomcration 19 5.1 Bintorinf tO $.2 Pollotiftinf 21 5.3 Coot Data U $.4 Fallot Production and Hoat-nardanin« 23 -4 -

1. Iron Ore Hin«rait A large portion of the common ore end rook-forming minerale con- tain appreciable amounts of iron. But there are only eix ironbearing minerale containing sufficient and appreciable amounts of iron. These are available in abundant quantities to be potential sources from which iron may be economically obtained. The six ironbearing minerale are as follows with Fe content in pure mineral in each case:

i) Hematite Fe 69. # ii; Magnetite Fe 72.4fc iii) Ooethite Fe 62. # iv) Chamosite Fe 4# v) Siderite Fe 48.?/> vi) Pyrite Fe 46.6;' The wide variety of conditions under which iron is concentrated in the earth, the physical and chemical nature of these concentrations, their mineralogical and geological environment and the complex procese which contributed to the concentration of iron in ore deposits, aooount for pe- culiar characteristics of each deposit.

J - !> -

2. T'ajor Deposits

The major iron or« producing regions of the world are USSR, Canada and West Indies} USA, Mexico and Contrai America} South America; Middle Last, Asia and the Par ^ast ; Africa, Europe and Australia and Few Zealand.

In USSK, the biggest deposits are in Ukrainian Hepublic (Krivoy Hog and Kursk magnetic anomaly) which are of Lake Luperior type, 'iaberg type of deposits are found in the "¿astern slopes of the Urals. Orse, of Vagnitnaya type and those of ¡inette type are found iv Yurgay and '/.'estem Siberia areas. Large deposits axe found in Kazakhstan, Siberia and Caucasus regionB.

Canada and ^ect Indies

The deposits of Canada and 'fest Indiotr are located in Appalachian, Grenville, Labrador, T.outwebt and I.'orthern Canada, Cuba and Dominican Republic. These are generally of Lake Luperinr, ''agnitraya and Taberg types and mostly contain hematite, magnetiti; and goethite. Siderite, pyrites and chamosites are also sometimes fourd associated.

USA and Mexico

The important deposits of Ur!A occur in Vesabi, Guyuna, Verni lion, Fillmore, Gogebic and Lake Cuporior regions. 'i'hese are mostly of Luke Superior type but sometimes Kiruna, Vaberg, 'îagnitnaya and Clinton types also occur. Yhe principal minerals are hematite, magnetite and Siderite. The deposits of Central America and ì'exico are generally of Kiruna ard Magnitnaya types and contain mostly magnetita, hamatite and goethite.

South America

Argentina, Brasil, Chile, Colombia, Peru and Venesuela are the countries in this region where iron ore deposits are located, deposits in Argentina are of Lake Superior and Minette types and contain hematite and magnetite. Bolivian deposits are of Lake Superior type containing hematite, 'the Bratilian deposits are mostly of Lake buperior type containing hematite. The deposits of Kiruna type are also found when hematite and magnetite are the principal iron-bearing minerals. The deposits of Chile are of Kiruna and "agnitnaya types containing magnetite and hematite as iron minerals. The-deposits of Colombia contain goethite and are of rinette type. The deposits in Peru are mostly of Fagnitnaya type containing magnetite. Lake i-uperior type of deposits are found in Venecuela containing hematite. I'iddle Last, Asia and Par TJast

Saudi Arabia, Israel, Turkey, Iran, Afghanistan anO •"'•deist an comprising '.'est Asia, have iron ore occurrences. ïhe depoeits of Laudi

V- J -6 -

Arabia are mainly of Laico Superior type and contain mostly hematite with magnetite minerali nation sometimes. The deposits in Israel are of hematite and goethite. The Turkish deposits are mostly magnetite and are of ,'a£ritr.aya type. Similar type of deposits occur in Iran. The deposits of Afghanistan contain hematite and siderite. í'agnitnaya type and bedded type of deposits are found in Pakistan with magnetite and hematite as principal iron-bearing minerals.

¡•'iddio Asia constitutes India, Sri Lanka and Nepal. Indian iron ores are of Lake Superior type and also of Massive and Taberg types. The predominant iron-bearing mineral is hematite and sometimes goethite and magnetite. The Sri Lanka deposits are of residual lateritic type ñnd mostly contain goethite and somet-mes magnetite, hematite is found ir /'epal and the deposits are of bedded type.

The eastern Atsia consits of ^urma, Thailand, Laos, Cambodia, ï'orth vict-î'am, 'alaysia, Indonesia, Philippines, China, Hong- Kong, forth Korea, Louth Korea and Japan. The deposits of Surma, Thailand, Laos, Cambodia, ! ort h Viet-' an, ''alaysia, Indonesia and Philippines are generally oí "agr itnaya, residual lr.teritic and bedded iron nand types. 'iiiece contain regnetite, goethite and hematite as iron minerals, ¡"agnetite-heratite are tne principal iron minerals of the Chinese deposits whicn are of ^.ake Luporior, 'inette and Hagnitnaya types. vhe düporit:; of úorea CJTQ mainly 1 agnitnaya type containing mostly ni^nctite and sometimes hematite. The deposite in Japan are of resi- dual bog and hodded iron sand typeu containing magnetite, ti-magnetite, goethite.

Africa

Deposits of Africa are of ''inette, Lake Superior, Bilbao, Taberg and ¡'agnitnaya types and mostly contain hematite-magnetite, hematito- goothite, henatite-pyrite (ochre) and ßiderite-goethito.

Europe

Portugal hae l'inette typo of deposit consisting of hematite and magnetite and sometimes siderite and Chamosite. In '¿pain, Bilbao type of deposit is in predominance with hematite-goethite as iron minerals. Preach ores aro of 'inette type and contain sidcrite- goethito. The ores of United Kingdom are also of l'inette type but cortai" cha^oeite-goethite-homatite. The deposits of i'orway are of bake i.uperior, "agnitnaya and Taberg types containing magnetite- hematite minerale. The f-wedish ores are of Kiruna and Lake Superior types containing magnetite, magnetite-hematite minerals.

The oros of Federal republic of Germany are W Hinette type, mostly containing hematite-cha-Tosite-siderite with occurrences of goethite also in some of the areas. Ores of Austria are of Bilbao type containing mostly siderite. Oros of Italy and Yugoslavia are mainly of Bilbao, Minette and , Magnitnaye. types with magnetite, siderite, ciderite-chamoeite mineral».

._ .J -7 -

Lateritic deposits aro predominant in Greece with goethite as the principal economic mineral. East Germany and Chechoslovakia have Minette types of deposita. Poland and Romania, both have ferruginous carbonates containing siderite-magnetite-goethite. Bulgarian ores are of Bilbao type and oontain hematite, siderite, goethite and magnetite. Australia and New Zealand The Australian deposits are of Lake Superior, Algoma and Clinton types with hematite, goethite, magnetite, hematite-magnetite-goethite and magnetite-pyrite minerals. The deposits in New Zealand are of aluvial and sedimentary natura and oontain magnetite and goethite as the main iron minarais. • ö -

3. Production and Iteserves

Production of iron ore in the different countries ir given ir 'i'able 1, and world distribution of reserves in Table 2.

Table 1: World Iror Ore Production

I n m 1 1 1 i on to n s Country 1973 1974 1975 1976*

Algeria 3.130 3.792 3.300 3.200 Ircela. 6.04e 4 . 960 3.360 3.300 Australia 63-566 96.668 97.365 92.400 Austria 4.211 4.246 3.633 3.764 Belgi tun C.116 0.123 O.093 0.063 Prazil 53.019 79-973 66.493 70.oco Bulgaria 2.774 2.664 2.337 2.300 Canada 46.200 47.271 44.745 56.00C Chile 9.65c IC.297 11.070 IO.500 China 50.eco 51.000 51.OOO 50.OOC Colombia 0.442 0. 5C0 0.623 0.600 Czechoslovakia 1.672 1.666 1.773 1.650 Denmark 0.012 n.006 - - •\'Ï'PL 3.130 3.792 3.300 3.2C0 Finland 0.6fc5 O.934 O.766 O.7OC F'rance 54.754 54.730 50.142 45-543 ¿laut Germany O.520 O.250 O.59O O.50O West Germany 6.429 5.670 4.273 3.034 Greece I.P42 2.C01 1.965 2.154 Guinea - - - - Hungary O.68I 0.595 0.366 0.631 ¡ionf Kong 0.151 0.160 O.I6I 0.037 India 34-426 34.230 4O.271 41.400 Iran 0.600 0.620 0.650 0.650 Italy 0.675 0.795 0.739 0.643 Japan 1.007 O.760 O.942 C.600 "orth Korea 8.100 8.100 8.200 6.100 bouth Korea O.467 C.493 O.525 O.500 Liberia 34.620 36.000 36.500 35.000 Luxembourg 3-762 2.686 2.315 2.079 Malaysia O.516 C.468 0.349 0.300 Mauritania 10.416 11.110 8.500 8.000 Mexico 5.736 4.902 4.621 3.300 Morocco 0.376 Q.534 O.554 O.350 Motherlands - - - - Korway 3.970 3.916 4.O64 4.291 Peru 8.964 9-563 7-753 7.000 Philippines 2.256 1.616 1.352 1.150 Poland 1.413 I.296 1.192 1.100 Portugal 0.057 C.O24 0.045 0.043 r -9

Table It continued - World Iron Ore Production

I n m i 1 1 i.on te n e Country 1973 1974 1975 1976*

lihodesia 0.550 O.55O 0.600 0.600 Romania 3.234 3.205 3.O65 2.300 Sierra Leone 2.4OO 2.508 2.500 2.400 South Africa 10.955 11.734 11.191 15.684 Spain 6.901 8.613 6.617 7.7OO Sudan - — _ Swasiland 2.148 2.055 2.232 I.932 Sweden 34.727 36.153 30.867 30.526 Switzerland - — _ Thailand 0.036 0.036 0.032 0.020 Tunisia 0.611 0.620 O.652 O.5OO Turkey 1.861 1.531 1.990 1.000 U.K. 7.IO5 3.602 4.490 4-563 U.S.A. C8.eoo 65.917 61.351 61.200 II «' ^ Î! 216.1C4 224.8t'3 232.8C3 239.occ Venezuela 22.660 26.408 24.104 23.000 Yugoslavia 4.670 5.034 5-239 4.265

'..'OlïLD 851.2C0 699.100 695.700 875.300

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'i'hc above briof description of world iro- ore resourcoc ¿ives an indication about tho varieties of iron orea found. liach of thee* deposits have their own characterietic features, variations in iron oortont, wireralogical assemblage, particle size of iron minorale and thoce of associated economic and gangue minerals, etc.

Vhfc world over, higher grades of ores aro gradually getting depleted due to so-ie type or the other of selective mining. During mining of these high grade ores, low grado ores, which may be present as overburden and capping or occuring in situ along with good grade or«:, get admixed. Vhis admixture becomes inevitable where large seal« mochar i Bod mining is resorted to.

Thus, in mont cases, some kind or the ether beneficiatior. of the run-of-mine ore has to be adopted to ensure an accepted and consistent quality of iron ore of desired chemietry for iron smelting. Prepared burden for iron nmelting is of paramaout importance, necessitating sis« reduction, screening into eise grading and improving the chemical com- position of the ore by employing beneficiatici techniques. -12 -

4. Peneficiation methods

Depending upon the mineralogical and petrological characteristics, different methods of boneficiation are employed to suit a particular ore. The methods include crushing, grading, Biting, washing and wet screening, gravity treatmert, magnetic separation, froth flotation, reduction roasting, thickening and drying. The overall ber.eficiation flowsheet may comprise the use of one or more of the different methods. The criteria for determining and finalisation of treatment flowsheet, are the cost economics of the process, requirement of the quality of end product and the possibilities of finding use of waste products; these are primarily governed by the mineralogical characteristics of the or« under study.

The various boneficiation methods are briefly outlined below:

i) Crushing: The ore as mined, is generally of 300-400 mm in line. Hequirement of sise of ore for us« in blast furnaces are that the ore should be of over 10 mm sise, with the top sis« of 50 to 30 mm. Crushing is done employing jaw and/or ¿yratory crushers.

For some types of ore, such as the Indian iron ores, wet screening of crushed ore, has to be adopted due to the sticky nature of the ore and presence of clayey matter with the mined ore. The screen undersize, namely -10 mm fraction is dewatered and slime rejected in spiral or rake classifier.

ii) Grinding] In some eases, suoh as with magnetite ores and taeomites, the ore is ground, either wet or dry in ball and/or rod mills, with a view to liberating iron-bearing minerals from gangue minerals.

iii) Washing: Lateritic ores and the ores admixed with aluminous clayey matter, are scrubbed with water in log-washers, cylindral or conical type of washers fitted with lifters, for loosening the adhering fines. The scrubbed ore is then wet screened on a double-deck wet vibrating screen to separate clean lumpy ore free from adhered fines for direct use in blast furnace and free flowing fines for use in sinter plant.

iv) Gravity methods: a) Heavy media separation: Aqueous suspension of ferro- si licon or magnetite, finely ground, is used to separate hematite, goethite or siderite from lighter gangue minerals. The eise of ore treated is normally -30 mm + 4 mm. However, finer sise can be treated in heavy media cyclones. b) Jigging: Harss or lien i er types of jigs are used for ore in the size range of -25 mm to 0.5 mm« c) Humphreys' Spiral: The sise range of feed to spiral is generally -1.5 mm to 0.1 mm. Sometimes specular hematite of as fine a size as t%' passing 150 microns, has been successfully treated on spirals.

w.' - 13 -

d) Shaking tables: The Bise of feed is almost same eie, used for spirale, fables are generally employed for ro-cleaning of fine gravity rougher concentrates. e,i Cyclones: Cyclor.es are used for recovering heavy minerals from fine gangue particleB from slimes.

v) ragnetic Separation: a)Strongly magnetic minerals like magnetite are separated from non-magnetic minerale employing low intensity wot m-f;netic separator. The separation is often preceeded by desliming the foed for better efficiency. b) Low intensity dry magnetic separation: This is used for pre-concentration of strongly magnetic minerals and for treatment of beach sands for recovering ilnenite and other magnetic minerals. c; high intensity magnotic separation: Vhis iti ußed for feebly magnetic riñerais like limonite, spocularite, goethite, etc. and can be wet cr dry. In case dry separation it employed, the ground ore should be almost free from adhering gangue minerals like cle¿s.

vi y Froth flotation: Flotation is employed for fine grc.ined low grade non-magnetic ores such as siderite-hematite oree, and specular hematitic ores. pH of the flotation pulp could be weekly acidic or alkaline depending upon tho minerals to be floated and reagontt uned. Tall oil, alkyl sulphonatee, sodium fluosilicic acid, ligneous tar, fish fats, etc. are the common flotation reagents used.

vii; lectrostatic/high tension separation: This method in used for further upgrading fine gravity concentrates, and helps in removal of undesirable minerals like apatite, micas, hypersthenes, etc. from iron-bearing minerals.

viii) Low temperature magnetising roasting: The method ie employed for fine ßramed, non-magnetic or feebly magnetic low grade ores con- taining hydrated oxides and sometimes siderite. The roasted ore is then passed through magnetic separatore to repárate magnetics from non-magnetic gangue minerals.

ix) Sewatering and drying: Fine concentrates are thickened in thickeners, filtered and dried for use. ?)ryingeould be partial de- pending upon the end une of fine concentrate.

*- -14 -

4«1. Beneficiation Practice« in some of the countries

Ores that contain 60-65 per cent iron, are generally considered of good quality and acceptable for direct use in blast furnace for smelting. The presence of the total ¿angue minerals consisting of oxides of silicon, aiui.,i:.ium and titanium up to a level of about t per cent, aro acceptable. Phosphorue and sulphur contents of the ore, should be as low as possible.

A brief description of beneficiation techniques for the various typt«' of iron oros found in different countries, has beer outlined in the following pages. It may be mentioned thet the exact process para- meters will dopend upon the amenability of ore to upgrading, nature and characteristics of the constituent minerale, ¡sizes at which different mirerais are liberated from each other, end-use of the bene- iiciated product, etc. The description given is, therefore, merely indicative of the broad process tech iques in each case.

1. U!>A

i; lirown Iron Ore: After crushing to the required size, the ore is scru!>')ed and wet screened to obtain clean sieed lumpy ore and free flowing fineB for ueo in r.intor plant or for palletisation.

ii) Oxidized Grec: Generally, after washing, the washed lumps and fines are subjected to gravity methods of beneficiation namely, heavy media separation, jigging, Humphrey's spiral treatment and hydro- Bif.ing. Lometimes, flotation is adopted to recover iron valúas from fine grained tailing! from haavy media circuit.

iii) Teconites: The ore, after crushing, is etace-ground ut-ing rod and ball mills in closed circuit. After rod milling, the pulp is passed through wet magnetic separator to recover magnetic iron oxide got liberated in primary grinding. The classifier over- flow fron ball mill circuit ie deslimed in cyclones and sand fraction subjected to anonic flotation to remove siliceous gangue minerals.

iv) fipflcularite» After stage grinding in open circuit rod mill and clored circuit secondary ball mill followed/desliming, the under- flow ir subjected to flotation. The rougher flotation concentrate after regrinding and hot conditioning, is refloated to yield a final concentrate analysing 67,' Fe.

v) Oolitic Hematite and Calcareous Ore: The run-of-mine ore analysing 36;' Fe is ground to a coarse site and after hydraulic clas- sification, treated in heavy media separators and jig* to produce high grade concentrâtes.

vi; Complex Magnetite, Hematite and Partite: The ore ie stage crushed and passed through magnetic separators to recovar magnetic iron oxides. The non-megnetio iron ore is recovered by froth floration after grinding. - IE -

The oroE fron Benson nir.es containing mcgnetite, mrrtite and hematite, are mined selectively and crushod reparately. '.'he me-gnetite. ore is beneficiated by magnetic séparation after stage crushin/r and jigging. The non-magnetic tailings are farther ground fine in ball mill and passed through a cet of magnetic separators to recovisr magnetics.

Partite is upgraded in humphrey's spiral after size reduction. '.ihe spiral tailings are subjected to flotation for recovery of nenatite ore.

vi^ "appetir ore fr^ "eratiec :,inirg Co.: After stage crushing and magnetic cobbing, the "wnetics are grourd ir ball mill and subjected to ">~,=7>f!tjc soparatior. í'he ror-m.agretic porti or after dos/lirir.^;, is; floated for differentia] separation of pyrite, pr.osphetes r.r.d specular hematite, '.'he sequence of recovery of different minerals is - first x-uthate fintatio^ for recovery of pyrite, the- fatty acitì fl^tatior for apatite :md f'irall\, flotation oí' hematite uning oulphonatefc-.

2. £ wede^

i) 'apnetite Creí:: ,'hese types of orca found in i'iruna, ¡'alTi^erget, (iraníes >erg aro upgraded .y repeated magnetic separrtions. If hematite is aleo pre sert, then the nor,-ma<_netic tailings arc trected L in jigs, Gha.'.in0 tables for its recovery. The core :.n trat o analyse ov¿,,lor ¡rr tío".

ii; liomatita Ore: \:ie on. after coarte crushing is subjected to ¿tripa procest or heavy •••odi.-. t;ep-a-¿tion usirr ferro-si licor as me- dium for the latter, vhu liner fractionr of ore are treated in shaking tablee and Humphrey' s spiral.

¡sometimes flotation is adopted to recover associated econoric minerali; liko apatite, .irulsifiod tall oil is the reagent ured at a pb of £.3 to recover apatite. Hematite is floated after lowering the p>. to Voout 6» i'he. raw ore analysing ij' Fe and 0.C2, r, ir. up- graded to C'y' Fe and C.Ol;' P. The apatite float analyses 0.3,' P.

Skara ard other types of ore such us those found in Bodas, are first subjected to dry magnetic sep&ration at about 20 mm size, followed by ball nil lint ^r,d flotation of pyrite. The flotation tailing after high inter.sity wet magnetic separation, yields magnetite concontrato separately.

3. Canada i) bpecular Hematite: These are low grade and friable occurirg in southern part« of Labrador - Quebec district. Generally, after autogenous grinding, the gnurd ore ir treated on spirals. If, however, super high grade concentrate is needed, then magnetic sep?mtion and flotation are sometimes employed.

For spoculiir-he"atite-'r,ai:,re'tite »u irtziterj of La e C ml-and j.ake '.,'atush regions, humphrey's spiral tre;.-reri it: adopted to produce concentrât- s analysing W-66 If'e.

V- _LJ - 16 -

ii, llenatite-Liderite: These nroc of Aliena, ••iabara and Cteop 1 ock are rcubjoctod to washing, gravity treatment such as heavy nodi a separation (cvclor.es/druTs) and jigging.

i i i ; Hagrotite: Crea from "ooso "ountains, í'armora, Ontario, etc. aro concontratod "ly low intensity magnetic separation.

Ma¿notite oree are mainly exploited as there are considerable reserves of these ores. Besides this, these ores are easier to beneficiate. However, purely magnetic seperation treatment becomes ecorot-ical if the proportion of magnetite in the ore exceeds 70•&Cy and the l?cs of iron in magnetic tailings does not exceed 12-14, •

The Veneficiation plants at Olenyogorsk and Krivoi Rog employing a combination, of ragnotic séparation, and gravity methods such ES spirals, heavy media separation and jigging, treat 20 m.tpy. For flotation, the ore is subsequently ground to a fineness of about 90; > passing through 2CC mesh screen.

> India Indiar iron ores, thouf-h generally of high iron content, are characterised by their high alumina content a"d presence of clayey matter. This makes the ore sticky, particularly in rainy seasons with the result that the ore crushing and handling plants come to a .-stand still during the wet weather. All the crushers, bins and hunkers, conveyors and chutes, get choked making screens completely blocked.

i) Vhe treatment for these types of ores (hematites), is scrubi irg with water to loosen the clay and then wet screening with powerful jets of water. The screen undor-size containing almost all the water and slimy matter, is treated in classifier. The classifier overflow carries away the slime which is generally a waste product. This is sent to water reclamation system. In case the slimes contain higher percentage of iron values, the slimes are treated in cyclones. Cyclone underflow after thickening and filtering, is sent to agglo- meration plant. The classifier sand portion is then a free-flowing material and can be used for agglomeration directly or after beneficiation by gra- vity methods. The washed lumps are clean, free from adhered fines. Nearly 30-40^ of the total silica in the ore íB thus eliminated as slime along with about 20-30/! of alumina. ii) Magnetite-hematite Ores: These ores are found in Kudremukh and Ongole areas in Bouthexn parts of the country. Magnetic separation after grinding yields a high grade concentrate analysing over 60$ Fe. The non-magnetic tailings containing hematite, are treated in Humphrey's spirals for its recovery.

A typical flowsheet for hematitic ores is given in Fig. 1 and that for a magnetite-hematite ore in Fig. 2. -17 -

'*•*• 1» Typioal flowsheet for a hematite ora from Indi»

R.O.M. ort after chrushing to 100 nun sis« Fe, 56» Si02, 5-2» A1203, 6.5$

Scrubber t Double Deck Wet Vibrating, Screen (25 mm and 10 mm)

-100 + 25 mm -25 mm + 10 mm -10 mm

Pe, 62.3| Si02 1.4« A1203 3.8 Fe 60.4| SiOg 1.8| AlgOj 5-1 Classifierui * , 1 Í -100 mm + 10 mm -10 mm sand slimes lumps

Pe, 61.5; Si02, 1.6j A1203 4-3 Pe, 57-3| Si02 4.1; Alg03 6.4 Fe 29| SiO? 26.5 A1.0) 16.2 Feed for Blast furnace Reject

Gravity treatment

Cone . >F ST Tails. Fe 62.2J EiC2 2.4, Alg03 3.6 Fe 47.8| ÖiOg 6.0; Al^ 11.0 Feed for Sinter plant Reject

J .lb.

***• 2| Typical flowohoat for a mafnttiti-hoiratit« ort frota India

K.C.M. ora aftar cruchirg and grinding to 65 mash sin« F«, 371 Si02, 47J Alg03 O.C per oant

Low intensity Viet üagnetic Separator 1 r I Tagneticg h'on-magnaticc ¥ Shaking gravity Tabla i

Tabic Concentrate Tabla tai1 linge

l.ti»ot T Combined Concentrate

P«, 67.51 Bi0 + Al^C,, 5.5 P«r cant I 2 L203, Ftod for ranter Plant -19-

5. Arvlomoration ''echarieed lure* soale mini-g, crushirff and siting, and sub- sequent beneficiati on in many cases adopted to meet the ever-increasing exacting deirpnds of iron shelters, neoessarily produca larga propor- ti or e of fines, Bonetir.es up to jC per cent by weißht of the oro mined, beai don the fineB obtained in situ. In the case of magnetite ores, the entire concentrate quantity in in the form of fines. Thcne tines are utilised for ironmaking after sintering or palle- tising. - 20 -

5.1. '• ir. t «ring

Lintarine plant in an iron and steal plant acta as a scavenger of the plant, which irakés uroful agglomerate- sinter, utilising a wide variety of waatos such ae coka bréese, mill acale, flue duct, blue dust, limestone ar<ù dolerite fineB. '.'he procees hes a great flexibility to ateloTierate raw materiale with different physical properties and mineralogical compofcitiors.

Harlior batch sintering raohines, such as those of (îreenawalt and r'midth types, were used, These have been replaced by the con- tinuous machines of Dwight-Uoyd type, of different makes like Lurei, !>cDowell, .huntington-ileberlein.

The modern continuous ointer plants have large strand areas - 400 to jOO in , capable of producing 4 to 5 million tone of sinter par yoar. Introduction of grate-cooling syotema for cooling hot sinter, have helped in raising productivity and reducing solid fuel consumption as well as maintenance coats to produca good quality, highly reoxidiaed, fine grained sinter. -21 -

>2. Palletising

Felletizirg in r o sortiti to where the ora partidos are in ver;' fire for:' cither as beneficiatoci prodcut or naturali;- occurrin£ mine- ral like Mue dust. Vhe procer.n consisto of two principal steps: hilling •'rd induration. After £;rindir.f; tho ore, which could bo either v:et or dry, in open or closed circuit with the- rill, dewat^rirj and parti il dr; ir£-, ¿ryer pellets of dorired £;ize, ere rnde uit.>. the additi-y- of üuitaMe Mr.der. Gollete can >o riii'ìe ir dru-, dice or cv-e t;pcr: of nei letizerà, '-'he '.ifillinfc drur requires teperate soroc-r- ir£ facilities to recirculate undornized .olleta lack irto tho "r.;illir.¿ circuit, v;ncre<-¡ü l'or pelletizirg discs and cone», serrate cercar ir ¿ is not r^rrally required, as nizir¿ iß d're ir. during tho bailing operali en and or.lv the da&ired size of pellets are dÍFcn¡_r^ed.

'"'Indern co^Torly used are bentonite, limestone e.vd hvdrated line.

l'V.r i,takir.i; pellets of good quality lu vir.* adequate <,reer strength and subsequently strerrth of heat-hr.rderod pellets of good reduci M Lit,; , choice of type of grind, the citie to v.-hich the ore should be ¿round 2nd the epecific surface area of tho ¿round material, the schedule of drying and prc-heating, firing end cooling cycles, are the irportant parameters which should be carefully controlled. is achieved Induration of pellets by heat/in vortical shaft furnaces, travel- line h-irizenta'. grates, ¿ratc-kilr combinations and circular-grate pelietising system. In all of these, the induration pncesB involves drying of the ¿reen pelleté, pro-ho:>.tir.£ to induration temperature, firirg at the required tempérâtîcn, and soaking for a definite period to create iron oxide and'or a slag bond formation between the ¿rains, followed by regulated cooling of the product, strict control of dz-yirg and heating cycles, it; important to maintain product quality and avoid Buch problems as spalline, premature rellet breakage, and cluster for- mation.

Cold-bprded pellets: A development in recent years has been the introduction of cold induration procéseos. Orancold, Cobo and several other processes have been developed. Special types of cements (which do not certain sulphur^ are uted with the pe'letiaing feed befora bal- line« Tho green balls, sometimes coated with iron concentrate fines to prevent cluster formation, are allowed to cure and harden for periods upto 5 week«. 8 to 10 por cent of cement is normally required.

In cate bonding is achieved by addition of lime, the green pellets »fter partial drying are allowed to harden at about 12C°0 to 150°C ir a carbon dioxide atmosphere under pressure.

_ __.t> - ?? -

5.3« Cost Data i) Iron Age 'ietalworking International (January and February, 1975) entínate capital costB for installation of a 5 million tons per annum palletizing plant in Iran, to be 1100 million!} and 1111 million» for a 6 million tone per annum plant in Japan. ii) Arthur D. Little Inc. estimate average pellet costs in U.S.A. to be between tl6.6 and 119«3 per short ton of pelletB of grade 63.6-64.8 per cent Pe. Average ore costs have been computed to be 10.2034 to 0.2688 per short ton unit contained Fe for average ore grade to be 55.4-65.8 per oent Fe. Sinter has been coated by discounting lump or» costs by 2.0 cents per short ton unit of contained Fe. Capital investment cost for a 100 tpd sinter plant has been estimated at 5100,000, and for a 1000 tpd plant, the coat will be approximately 4550,000.

J -23-

5-4. Ptllst Production and Heat-hardening

World pellet production in various regions using different indurating systems is given in Table 3.

Table 3t Pellet Production in 1975 in million tons

Morth Latin ¿astern Vie stern Middle Austral- Africa Total America America iJurope .iurope East asia

Shaft furnace 17.30 1.50 1.25 0.85 3.00 ?3.90 Travelling grate 37.65 10.60 21.10 7.43 2.CO 6.70 e>4f Orate Kiln 42.25 7.5O 2.00 9.65 61.60 Lepol furnace 0.45 C3C 0.Y5 Circular grate 0.75 0.75 Grancold 1.60 1.60

Total 97.20 12.85 21.10 16.23 - 4.85 19.65 174.06

bouree: ::. and S.C., Íjteel/CU. 3/lt.3, Add. 1.

The share of the developing countries in 1975 was about 22-23 million tone produced from 14 plant ss located in 10 countriee. Vhe projected production for 1985 in thu world would be 43} million tons, out of which the share of the developing countries would be about 165 million tons.

Data pertaining to Bhaft furnaces, travelling grate and grate-kiln installations of some pellotising plants, are presented in Tables 4, 5, and 6 respectively. M

3 2 s i i ¡ I I I Ï i- * «» N P

H M M » , sis 8 7¡ S •S~ r- m

** f o « r- a o •A ri

K S 00 lA 00 1 «o * . *". * «- M *\ 9 A «ó g iA »-.? m ¡«J * * me»°í ^ e¡ ci ¿ci

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3

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fil SI <•> O

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«M IO CM * * I * s; ïi 2 & .A 8MJ « M»

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l'i *"r *'F s ii is jï |ï ii I § ir a flu ?¿, r¿-.. L -»¡c- ÍÓ Si, lô '1 ir r -s» - • •i i i i

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m «sì 3 r- «si *

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3 S 9 .A 4 .A iA A .A

tu NO « .A ' * À •o 8 SD ? ' ï ï !

o * R Ì ' ft «0 R «0 9 5 i «o si iA ¿ J O» * so ,A i | r-

¡S IR « * «

e S S •i i ?? f î ? i I ïï i " " ! ' " i! H ! ! I 2 n Mlt. «¡I o si ;!iM! 31 ft K a Iß -32 -

Sinter va. Pellet

It io well known that pellets are usually produced near the source of iron ore and sinter is made at the smelting plant. Sinter production pormitn a much larger part of the added valuos to be credited to the country where the ore ir processed into iron and steel than does pellet manufacture. This extra benefit usually favours the iron- and steelmaker, who therefore hes a £ood reason for bias towaiù the use of sinter over pellets.

Technically, a good quality self- or superfluxed sinter having adequate strer/'th and clo£:e-sizing, possesses same of sometimes, even superior r>ctal- lur¿-icpl. physical and chemical properties to that of oxidized pellets. ïhe choice of ¿inter or pellets as a burden material in similar circumstances, is usually a m.-vtter of pergonal preference, within constraints over which the operator has little control. Besides this, the choice is also dictated by tho 1 cal conditions and chrracteristies of the ore.

Pellets are largely preferred in "orth America with a view to utilizing huge de.;~sits of teonite. Vhe concontrates produced are in fir:ely divided state nnd are excellent feed material for pelletiaing.

Japon imnnrtc hu¿;,e quantities of high grade lumpy ore and fines. r.'he fires are sintered and uí,ed ir. blast furnaces. However, captive pel letizi^ plants arc bein,;; put up by ¿ore i.teels at tleir Kakaçawa and r.'hdrhama workB based on imported fines and concentrates. his is reported tn be mainly to avoid pollution problems about which there are stringent pollution control regulations.

Physical Vorm of Iron Ore Consumption,

'brld Production ratios of einter-pellote and pie iron ; shown in 'i'able 7 below, indicato the enormous efforts beine made to improve the burden prepara- tion.

Table 7: halation between production of sinter 'pellets and pip iron.

Country 19 6 0 1973 Winter and Pellet/pig Iron Sinter and Pellet/pi^ Iron

Kederal uepublic of Gorrany 0.779 1.202 Aurtria 1.127 I.45O Belft1 urn 0.337 1.13C Canada C.774 1.3C0 ¡Jnitod íJtates 0.777 1.246 Fra»' c o C.446 I.O99 • urf ary 1.996 Italy 0.766 1.270 Japan C.67C 1.3C9 Lux#7i"oour^ 2.2C7 ''•thorlvdo C.733 1.CC4 Poland 1.292 1.2T.1 Jnitod .'irgdom O.39P 1.139 J.r.. J..K. 1.732

Lource: and ;..(.:. - fiteelC.:. 3 V'3 7/-d. 1, ^ ~\\ -

'"able r srrv'K tho cr-mrir^ patter* cf irv ore rcTuiru-'ont. it n;* bo roar that tr.i proportion of cintar í'cod ir the iror T¿ de"\ind hue ce^or-ill; r-rmnod unaltered, whoroie th« ah:!-« loct by lunpj. ore, i H {jilted \ pelleta.

.'able C: (;har~IT- r^.ttorr, of Iror Cru aouire-ort (ir. por ce»>t]

tjpj of Kood 1^'tj 1970 i9cc v>3

iOr.-.v ore 39-4 3.4 22.*" 20.0 Lirt«r f'ßod 53.C 5C.3 4Í.0 n.o Pellet 7-e 16.3 30. C 3?. o

1CÍ .c 1C0.C irr.f.' Ko.r

Lourcc: ¡í¿í_lrruvatior. "77".

l'ip. 3 nievo the ¿ro'.ith pattern of fovca^otior of lur.p; ore, uirtor rrd pelL-jtt ir diffyrort roriore ^f tho world. It '-a;- Ho ¡;3en that KìTì* er contusoti or, predr/rJ-ata^ in >;eterr and '..'cbtarr' "uropo, .T"d ir Japan. Ir the '"ite'l ! tates nrd '"arada, tho pattern was similar until the ORI-]; 19t!~'c, when pr.llets becado the pre- ferred iror burder naterií'l. Ir Latir .'.rerica, lump;' orer. ira utili the principal burder, raterial, but cintar concrumption ic aleo steadily rising. -M

ivC U.S.A. W*S*^tVN ¿UfOfHI PteïIctj

.. ,jiiiU.r

ri 1 J J v/v i'/fo ïjVo

_ Japan Atstcrn Europe and USSR 20C) r-

'¿M.VJÏ 1'jO ïïintor

100 u-

Luí«]) JiUff.i; Pellets „-' PfJlc-t: Z±- £'-....1 I L- J I I k,rrü:lll 1 I l'M> i

Cañad« Utin America Pellotu 20 r IS y ùump ^r yi.',itïi<:T ,,.» 10

r -^y J "*^ ^„Pelleta i—«¿C L I i I I -i,. 1 .'\""\" 1 1 I960 1970 l'ß'iO l'Xo ]¡//o I(;«ü

'ir-u-ö 3 - Promotion of iror-oru conGumption tonnage by physical form (in million metric tone;

Lnurc«: Jack H. Miller - 3rd Irterreeioral Syxposium or Iron ard f.teol Ir.dustry, 1973J rraBil.

W~ - M -

HOMK&OOXCAL PROFIL*

Ol

HOK KAKTMJ - 36 -

C0WTBNT8

Bo. Pago Wo»

1. Introduction 37 2. Influence of Burden Constituents 37 3. World Iron Ore Production and Reservas 3<, 4. Coke 43 5. Formed Coke 49 6. Charcoal 52 7. Crude Petroleum 53 8. Natural Qas 55 9. Fluxes 57 10. Manufacture of Pig Iron 57 10.1 Blast Furnace 58 10.2 Changes in Conventional Blast Fumaos 60 Technology and Cost Figures 10.3 Eleotric Ironmaking Practices 81 10.4 Pre-reduced Iron Ore/Pellets for 82 aielting 11. Economic Considerations of Irornaking Processes 63 12. World Production of Pig Iron 84 -37-

1. Introduction:

Pig iron is the intermediate form through which almost all iron must pass in the manufacture of steel. In addition to this, it is used in foundries for the manufacture of a wide variety of iron castings. Most iron ores may be used to produce pig iron. In current iron making practice, the definition "iron ore" is applied to any iron-bearing material that can economically be used at a particular time and place for the manufacture of pig iron. All the constituents in the ore that are undesired in iron making, are impurities. However, the mineralogy of iron ores often does not lend itself to the ready removal of many such impurities by known ore-treatments methods. It is therefore necessary to determine the naturra and amount of impurities and accordingly to control the composition of the iron ores in the smelting furnace. The wide differences in structure and mineral content of ores from different deposits are responsible for the considerable variation in the beneficiation methods that have been developed to remove or to limit the impuritieB. However, some impurities, notably silica, alumina and lime, play important positive roles in scavenging other impurities from molten iron. Nevertheless, the ironraaker would prefer to use highgrade ores containing a minimum of these scavengers and to add them only as needed, in controlled amounts, or to blend ores containing known amounts of different impurities.

2. Influence of burden constituents;

Iron Orea; *) Iron compounds; The iron content of ores that are used in blast furnaces varies widely from about 30$ up to 71$. Hematites are easier to reduce in iron smelting than magnetites, in spite of the greater amount of oxygen combined with the iron in hematites.Ores with a high content of iron silicate minerals have a low degree of oxidation and are difficult to reduce in the blast furnace. Ooethites and carbonate ores contain combined water and carbon dioxide which are removed in the upper part of the blast furnace. In order to obtain low fuel consumption in the blast furnace, the ore should have a high iron content so that a smaller amount of •lag is formed. II) Silica; Silica is ore of the most important gangue mineral in an iron ore. Together with alumina, it is a main constituent of an acid slag during the smelting operation. The amount of silica per- •issible in the ore is determined by the proper slag volume, which in turn, is determined primarily by the sulphur in the charge and, ••condarily, by the necessity of having a slag fluid enough to re- cover the molten iron. A decrease of about 1.5$ in the silica content of the ore will produoe a drop in slag volume of about 65 kg per ton of pig iron. It has been estimated that an increase of 100 kg in the amount of slag

*— _ _ J -ìò _ per ton of pig iron, raises fuel oonsumption by about 40 kg of coke per ton of pig iron.

III) Alumina: The alumina eontent of the slag of a coke blast furnace should not be too low. About 10 - 15 per cent of alumina inoreases the fluidity of basic blast furnace slags and thus makes it possible to use a higher basicity which facilitates the removal of sulphur. If the ore is high in alumina, its content in slag may be as high as 25 - 30 per cent. Such a slag requires a high temperature in the furnace to get the right fluidity, and produce high-silicon pig iron for foundry and Bessemer process as in Indian practice. If slags contain 40 - 43 per cent alumina, then these can be used for cement or aluminium industries. In case alumina content of the slag is low, desulphurization is not quite effective, which could be offset to some extent by raising the magnesia content.

IV) Lime: Lime is a dominant constituent of a basio slag. Its function is to form a fluid slag with coke ash, ore gangue and other burden impurities.

V) Magnesia: Magnesia, the other dominant constituent of slags, helps in reducing the visoosity of slag due to high alumina content. Dolomite is generally used in blast furnaces along with limestone.

VI) Manganese oxides: Most of manganese, if present in the ore, passes into the pig iron, and subsequently, a portion of this finds its way into the final steel.

VII) Phosphorus: Almost all phosphorus present in the burden will pass directly through the blast furnace and enter the pig iron. A high phosphorus content is a drawback, as extra lime is required for its elimination; thus slag volume and fuel oonsumption are increased and steel output decreased consequently.

VIII) Sulphur: Sulphur is contributed not only by iron ore but also by limestone and the coke used in the burden. Excepting a small percentage of sulphur which goes out as gas, it is divided between the slag and metal. Satisfactory removal of sulphur requires a basio

IX) Titaniumt In blast furnace smelting, most of the titanium oxide remains unreduoed in the slag. It is a strongly carbide forming •lament, and the titanium oarbide has a low solubility in molten pig iron. High titanium oontent give rise to blast furnaoe operating difficulties. However, in electric smelting, the operating difficulties -tt-

are not many and ao higher Mounts of titanium oan be tolerated. X) Vanadium: About 70-90 per oent of vanadiua present in iron ore passes into the pig iron. If the metal is not high in silioon or titanium, a large quantity of the oontained vanadium oan be oxidized quickly when refined by the Bessemer praotioe. A vanadium-rich slag is poured off for the production of ferro- vanadium, an important.: metallurgical agent. XI) Zino: If sino oontent inoreases beyond 0.2 per oent, operating difficulties begin to appear. XII) Copper: The entire amount of oopper present in the burden, will pass into pig iron and ultimately into steel. Snail percentages of oopper in steel increases its corrosion resistance. But if its oontent inorease beyond 0.3 to 0.4 per oent, rolling difficulties are enoountered. XIII) Chromium: Chromium oontent in pig iron is an advantage used for alloy steels. For ordinary steels, its presence is mainly a disadvantage. XIV) niokel: The entire amount of niokel will go into pig iron from which it oannot be removed by oxidation during steel making process. In some speoial oases, small amounts of niokel in steel •ay be of advantage in improving mechanical properties. But in most instances, its presence is undesirable.

XV) Arsenic: An exoess of arsenic causes oold brittleness i steel produced from pig iron containing arsenic. However, upto 0.15 to 0.25 P«r cent, is acceptable in ordinary steels, and upto 0.05 *° 0.10 per oent in steels for temper hardening. XVI) Lead: Lead is rare in iron ores. It does not enter pig iron but damages refractory lining by penetrating into it. XVII) Tin: The entire amount of tin present in the ore goes into pig iron and thence into steel. Even in relatively low amounts, it is harmful in steels in damaging the deep drawing properties and also osases brittleness. The steels should not oontain more than 0.05 per oent of tin.

3. World Iron Ore Production: Production of iron ore in some of the oountries is given in Table 1 and world distribution of ore reserves in Table 2. -4t -

Tabi« 1 World Iron Ore Production

In million tons Country 1973 1974 1975 1976

Algeria 3.130 3.792 3.300 3.200 Angola 6.048 4.98O 3.360 3.300 Australia 83.568 96.688 97.365 92.400 Austria 4.211 4.246 3.833 3.784 Belgium 0.116 0.123 0.093 0.063 Brazil 55.019 79.973 88.493 70.000 Bulgaria 2.774 2.684 2.337 2.300 Canada 48.200 47.271 44.745 56.OOO Chile 9.65O 10.297 11.070 10.500 China 5O.OOO 51.000 51.OOO 50.000 Colombia O.442 O.500 0.623 0.600 Czechoslovakia 1.672 1.668 1.773 1.850 Denmark 0.012 0.006 Egypt 3.130 3.792 3.300 3.200 Finland O.885 0.934 O.766 O.70O France 54.754 54.730 50.142 45.543 East Germany O.52O O.250 O.590 O.500 West Germany 6.429 5.670 4.273 3.034 Qreece I.842 2.001 1.965 2.154 Guinea Hungary 0.681 O.595 Ó.386 O.631 Hongkong 0.151 0.160 0.161 0.037 India 34.426 34.230 40.271 41.400 Iran O.6OO 0.620 O.650 O.650 Italy 0.675 0.795 0.739 0.643 Japan 1.007 O.78O 0.942 O.800 North Korea 8.100 8.100 8.200 6.100 South Korea O.467 0.493 O.525 O.500 Liberia 34.620 36.000 36.500 35.OOO Luxembourg 3.782 2.686 2.315 2.079 Malaysia O.516 O.468 0.349 O.300 Mauritania 10.416 11.110 8.500 8.000 Mexioo 5.736 4.902 4.621 3.500 Morocco 0.376 O.534 O.554 O.35O Hetherland Norway 3.970 3.918 4.064 4.291 Peru 8.964 9.563 7.753 7.OOO Philippines 2.256 1.616 1.352 1.150 Poland 1.413 1.296 1.192 1.100 Portugal O.057 0.024 0.045 0.043 Rhodesia O.550 O.55O 0.600 0.600 Romania 3.234 3.205 3.065 2.300 Sierra Leone 2.400 2.508 2.500 2.400 South Africa 10.955 11.734 11.191 15.684 Spain 6.901 8.613 8.617 7.700

J -41 -

Tabla 1 t continuad - Morid Iron Ora Produotion

I n •illion tona

Country 1973 1974 1975 1976

Sudan . Swaziland 2.148 2.O55 2.232 I.932 Sweden 34.727 36.153 30.867 3O.526 Switzerland - . - - - Thailand 0.036 O.036 0.032 0.020 Tunisia 0.811 0.820 O.652 O.5OO Turkey 1.861 1.531 1.990 1.000 U.K. 7.105 3.602 4.490 4.583 U.S.A. 88.800 85.917 81.351 81.200 U.S.S.R. 216.104 224.883 232.803 239*000 Venezuela 22.880 26.408 24.104 23.000 Iugoslavia 4.670 5.034 5.239 4.265

WORLD 831.200 899.IOO 895.700 875.300

Brtinated or provisional

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4* Coke; Coke for blast furnace consumption must be sufficiently fin and strong to resist shattering by handling, and crushing by pressure exerted by the heavy blast furnaoe-burden. It should be free of dust and fines, and in pieoes not too large for optimum speed of combustion. With a good coking coal, these physical properties can be controlled only moderately by the coking process. As the coal is heated, it becomes plastic at 330° to 475°C, forming a fused mass irrespective of its form when charged into the retort. As bituminous coal is heated through this range of temperature, volatile matter is given off, rapidly at first, then slowly up to about 9500C The coals making up a blend, so far as possible, should have about the same plastic range. Slow heating through the plastic range increases slightly the hardness of the coke. The size of the lumps of coke depends largely upon the thickness of the coal charge and whether or not it is heated from one or both sides. As to the chemical composition, a good metallurgical coke will oontain very little volatile matter - not over 2 per cent - and 85 to 90 per cent fixed carbon. The remainder is ash, sulphur and phos- phorus. The phosphorus content, O.OI8 to O.O40 per cent for making Bessemer iron, preferably should be low also for basic iron. Sulphur varies from 0.6 to I.5 per cent, but is desired as low as possible because ooke is the chief source of sulphur in the pig iron produced. Standard specifications for foundry coke call for a volatile matter oontent of 2 per cent, a maximum sulphur of 1 per cent, a maximum moisture of 3 per cent, and a minimum fixed carbon of 86 per cent. Shatter and tumbler test» are aleo specified, but no standard for combustibility has been adoptea. These requirements are controlled through selection of the coal, which should be low in sulphur, free from slate or removable refuse, and give and ash which has a moderably high fusion point in a reducing atmosphere. There are three principal kinds of coke, classified according to the methods by which they are manufactured : low, medium and high temperature coke. All the coke used for metallurgical pur- poses must be processed in the high ranges of temperature if the produot is to have satisfactory physical properties. The most desirable blast furnace coke is made from mixtures of high-volatile and low-volatile coals, pulverized and blended and then coked in ovens capable heating the mass to an uniformly high temperature. Manufacture of metallurgical coke: There are basically two methods for manufacturing metallurgical coke, known as the (i) Beehive process and the (ii) By-product or Betört prooess. (i) In the beehive prooess, air is admitted to the coking chamber in controlled amounts for the purpose of burning therein the volatile products distilled from the ooal to generate heat for further distillation. (ii) In the modern by-product method, air is exlcuded from the ooking chambers, and the necessary heat for distillation is supplied from external oombustion of some of the gaa recovered from the ooking prooess. The temperatur. f ooking is somewhat lower than in the bee- - 44 - hive oven«. Beaidea natal lurgioal ooke, ooko braea«, ooke-oven «M, tar, «Monium aulphate, amonia liquor and light oil, are ih« prinoipal by-produote. Rofining of tar ami light oil, yield a largo variety of products auoh a« benaene, naphtaltno, pyrene, phenol, pyridino, «to., «to. In ordor to reduoe environmental polution, extenaive euooeaa- ful étudiai have been aada in U.S.S.R. on dry quenching of hot ooto inetead of not quenching. Tha world reaervea of ooking ooala ara given in Tabla 3.

W- J -45 -

Tabi« 3 t World Coking Goal Reaervaa

I n biljLion tona Country Hard Coking Coal Soft Coking Coal

U.3.3.R. 166 107 U.S.A. 128 60 China 101 Europe 41 38 Ooeania 14 11 Afrioa 12 India 11 1 Japan 1 South Aaerioa 1 Raat of the ragiona 12 1

Total 476 219

B. Satinate by Daaturo<)

Country I n billion tona

Latin Aaerioa Braiil 0.15 Mexico 0.21 Chile 0.07 Colombia 2.10 Aaia China 9.50 India 10.077 TaiMan 0.07 Raat of the ragiona 407.565

Total 429.732

V- >J - «ó -

About 90 per oent of the total world reserve of ooking, ejciit in relatively a few looations in the world, mainly in the developed oountries. Developing countries, other than China, account only for •one 2.3 to 2.5 per oent of the total world reserves. The estimates of ooking coal requirements in the world are given in Table 4. The figures foroast have taken into account the economy of coke being effected by improved smelting technologies, like oil and pulverized coal injection, oxygen enrichment of the blast, use of pre-reduced ore, etc. The figures are from a paper presented by Jack Miller during UNIDO«s Third Inter-regional Symposium on Iron and Steel Industry, held in Brazil in October 1973.

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Coke production figure! for soae of the oountries during 1974 are given in Table 5.

Table 5 t Coke Production

In million tona

Country 1974

Argentina 0.660 Australia 4.916 Austria 1.733 Belgium 8.030 Brasil 1.850 Bulgaria 1.308 Canada 5.233 Chile O.315 China 28.000 Goloabia 0.510 Cseohoslovakia 10.898 ftypt 0.360 Finland 0.O8O Franoe 12.282 Oeraan De«. Rep. 1.829 Federal Rep. of Oeraany 34.854 Oreece 0.372 Hungary 0.766 India 8.199 Iran O.O65 Italy 8.566 Japan 45.632 Korea Desi. P. Rep. 2.300 Xexioo 2.071 Netherlands 2.687 New Zealand Norway O.315 Peru 0.012 Poland 16.929 Portugal O.I96 Romania I.525 South Afrioa 3.600 Southern Rhodesia O.255 Spain 4.243 Sweden O.48I Turkey 1.241 U.8.S.R. 82.641 U.K. 15.776 U.S.A. 60.487 Yugoslavia 1.323

World 372.750 - 49 -

5» For»«* Coke» Attempts to develop new processes for the manufacture of artificial solid fuel suitable for metallurgical use, have been mainly inspired by the desire to use otherwise unsuitable coal- base materials, and world-wide shortage of good coking coal. Experiments have been made for the development of a new coking prooess aimed at obtaining a solid product similar to metallurgical ooke by means of blends partially or entirely made up of non- ooking coals and named as "formed coke". Although many processes have been developed throughout the world, the majority of installed plutts are based on two main processes: a) degassification and transformation of the coal into semi-coke to be briquetted with the aid of a binder; and b) hot briquetting of coal followed by distillation in special furnaces. The main advantages that can be achieved with this new technology are: i) enlargement of the quality range of the ooals to be used ii) better uniformity in coke size iii) extensive automation in the operating plants iv) better control of pollution problems, v) continuity in the coking process from ooal preparation up to the final product. It is well known that one of the main conditions for lowering the coke rate and increasing productivity of the blast furnace, is a satisfactory permeability of the burden. The "formed coke", with its well balanced briquettes, is certainly more suitable than the conventional coke for this purpose. Table 6 shows formed coke installations, experimental pilot plant scale as well as on commercial scale.

W- — - so -

Table 6 : Formed Coke Operational Processes

Output End Temperature Country Plant type Process tons/year Product range °C

1. Midland Coal Products U.K. Commercial 50,000 Domestic 900° boiler fuel

2. Caumore Canada Commercial 30,000 Metallurgi- 900° oal+Chemica

o 3» Balfour U.K. Pilot 50,000 Smokeless 700° - 900 domestic briquettes 4. Otto Germany Pilot 1,000 Smokeless 700° - 900° fuel

5« Humphreys and Glasgow Australia Commercial 60,000 Metallurgi- 800° cal foundry coke

6. Lurgi Spulgas India+other i Commercia 380,000 Smokeless 800° max domestic briquettes

7. Phurnacite U.K. Commercial 1 mill. Smokeless 600° - 900° domestic briquettes

8. National Fuel U.S.A. Pilot 35iOOO Metallurgi- 850o Corporation cal

9. H.B.N.P.D.C. Franee Pilot Metallurgi- 8500 (Soubrier) cal

10. Iniex Belgium Pilot 40,000 Metallurgi- 600° - 900° cal

11. Broken Hill Proprietary Australia Pilot 40,000 Ketallurgi- 550° - 900° oal

12. Schenok/ Oermany/ Pilot Metallurgi- 600° - 900° Hensel/ USA cal and Peabody Chemioal

13» Food Maohin»ry t.C.A. Coomeroial 70,000 Metallurgi- 1000° Corp. cal - S] •-

Tabi« 6 j continued - Formed Coke Operational Prooesses

End Temperature Prooees Country Plant typ, J**}* "" tons/year Product range °C

14» Lurgi Germany Pilot Metallurgi- 850° cal

15. B.W.V. Germany Semi- 36fOOO Cupola 900° coramercia Coke

16. Sapoznikow U.S.S.R. Commercia 140,000 Metallurgi- 1000° cal

17* Bergbau Forsch- Qermany Pilot 42fOOO Metallurgi- 500° ung Lurgi/BUY cal

18. D.S.N. Holland Commeroia 40- Smokeless 600° 80,000 domestic

19* ChPM Poland Commercia 220,000 Cupola 700° Coke

20. Sunoole U.K. Commeroia 160,000 Domestic 600°

21. Consolidated U.S.A. Metallurgi- 950° Ooke Co. cal

22. BMV (Bergwerks- Germany Pilot 40,000 Domestic 650° verband)

rd Source : Conti and Sacerdote - 3 Interregional Symposium on Iron and Steel Industry, Brasil 1973.

^- - «^2 -

6. Charooal: Wherever oonditiona are favourable, oharooal is used in smaller size blast furnaoe in plaoe of coke. Since oharooal is virtually ash free oompared with coke, one of the features of the operation is the extremely low slag volume produced. It is un- necessary to use hign gxadc limestone because silica must be added to the burden to make up minimum slag volume. This can be obtained by the use of low grade high silica limestones. Slag volume vary between I50 and 200 kg per ton, and all slag is tapped with the iron. Slag basicity is usually within thfc range 0.9 - 1.0 but sulphur can be kept at 0.02 per cent maximum despite low volume. The oharooal produced is screened to +4mm before being charged to the furnace. The screen under- size after pulverization is injected though the tuyeres of the furnaoe. Charcoal is highly reactive, but it is not strong and oannot withstand the abrasion of the charge in a blast furnace of the usual height. It can therefore be satisfactorily used in a shorter and smaller furnaoe of capacity, say, upto 400 - 500 tons per day. With a well prepared burden of sinter or pellets, a ooke rato of 75O kg/ton iron should be possible. However, suoh a furnace would need stoves capable of heating the blast up to 1100°C. As mentioned above, charcoal for iron smelting in relatively small blast furnaces, is being used in several developing countries which have a good forest wealth and a forestation programme. In Brazil, about 3 million tons of pig iron is smelted in small blast furnaces using charooal as the reduotant and for heat input. In western Australia at Hundo wie, an iron smelting blast furnace using charcoal has been in operation for more than two deoades. In India, the Viseshwaria Iron and Steel works at Bhadravati, has an operating charcoal blast furnaoe for the past several years. In Malaysia, at the plant at Malayawata Steel, iron smelting has been successfully in operation for the last several years using oharooal •ade fron rubber wood. - 53 -

7« Orad« Petroleum

Reserves and production of orude patrol tua for SOM of ih« oountries is given in Table 7.

Table 7 i Reserves and Produotion -Crude Petroleum

Country Reserves in Produotion in 1974 million tons in million tons

Albania 10 2.2 Al feria V58 48.66 Angola 199 8.7 Argentina 344 21.139 Australia 336 19.595 Austria 25 2.238 Bahrain 34 3.363 Bolivia 27 2.112 Brasil 102 8.442 Brunei 267 9.284 Bulgaria 2 0.144 Buraa 17 0.888 Canada 965 80.261 Chile 27 1.311 China 2,024 65.000 Colombia 89 8.686 Congo 127 2.455 Cuba - O.140 Cseohoslovakia 3 0.149 Denmark 39 O.O86 Ecuador 198 8.999 Hypi 386 7.472 Franoe 11 I.O80 Oabon 90 10.202 German Den. Rep. 2 0.75 Germany, Fed. Rap. of 69 6.191 Oreeoe 82 - Rungary 29 1.997 India 122 7.490 Indonesia 1,614 67.979 Iran 9,315 3OO.852 Iraq 4,724 96.940 Israel - 6.040 Italy 83 1.024 Japan 10 0.672 RumUt 10,469 128.101 Libyan Arab Rap. 3,039 73.364 Malaysia 352 3.844 Maxioo 433 29.56O -?4 -

Tabla 7 : continuad (Reservat and Production - Cruda Petroleum)

Country .Reserves in Produotion in 1974 •illion ton» in million tons

Morooco 0.024 Natherlands 44 1.461 New Zealand 26 O.I63 Nigeria 2,655 III.578 Norway 739 1.706 Oman 450 14.488 Pakistan 4 0.432 Paru 112 3.756 Poland 6 O.55O Qatar 720 25.059 Romania 174 14.486 Saudi Arabia 14,780 421.397 Spain 14 I.982 Syrian Arab Rap. 402 6.426 Thailand - 0.10 Trinidad and Tobago 92 9.641 Tunisia 69 4.139 Turkey 17 3.430 U.S.S.R. 6,607 458.948 United Arab Eteirates 3,397 81.071 U.K. 1,641 0.87 U.S.A. 4,629 432.794 Vanecuela 2,090 155.803 Yugoslavia 44 3.458

World 75,530 2,792.080 - tf-

8. Natural Qaii

Reterve« of natural gas and its production in 1974 ara given in Table 8.

Table 8 : Reserves and Production of Natural Oas in 1974

Country Reserves in thousand Production in •illion cu.m. Billion CU.B.

Afghanistan - 3,200 Albania 12 150 Algeria 2,837 5,621 Angola 50 Argentina 201 7,242 Australia 747 4,360 Austria 14 2.206 Bahrain 51 2,036 Bangladesh 830 Barbados - 2 Belgium • 63 Bolivia 132 1,735 Brasil 26 498 B**U!)Gi 193 5*000 Bulgaria 14 180 Burma 8 20 Canada 1,606 73,367 Chile 73 3,400 China 481 3,000 Colombia 43 1,700 Congo 179 19 Cuba - 19 Chechoslovakia 13 069 Denmark 20 Ecuador 116 10 Egypt 142 60 Franoe 155 7,628 Gabon 50 46 German Dea. Rep. 96 7,732 Germany, Fed. Rep. of 354 19,826 Greece 11 Hungary 86 5f094 India 68 717 Indonesia 425 5i732 Iran 10,602 22.126 Iraq 778 1,300 Israel 1 66 Italy 245 15|273 Japan 38 2,572 Kuwait 1.080 5,300 Libyan Arab Rap. 800 218OO

.J -56 -

Table 8 t continued (Réserves and Production of Natural Gas)

Reserves in thousand Production in Country Billion cu.m. Billion cu.m.

Malaysia 323 Mexico 317 13,950 Morooco - 59 Netherlands 2.180 83,703 New Zealand 168 303 Nigeria 1,423 574 Norway 549 - OB an 68 - Pakistan 439 4,600 Peru 37 530 Poland 136 5,528 Qatar 221 1,050 Romania 193 28,643 Rwanda - 1 Saudi Arabia 1,726 3,200 Spain 11 1 Syrian Arab Rep. 76 180 Trinidad and Tobago 92 1,418 Tunisia 82 201 Turkey 1 - U.S.S.R. 19*616 260,553 United Arab Biirates 766 1,800 U.K. 830 34,718 U.S.A. 6,715 586,531 Venesuela 1,215 11,633 Yugoslavia 42 1,447

World 59,195 1,255,250 - «J7-

9« Fluxes;

Lineatone and/or dolomite are used as fluxes. The functions of these fluxes are : i) to form a fluid slag with the coke ash, ore gancue, and any other charged impurities, and ii) to form a slag of such chemical composition that it will provide a degree of control of the sulphur content of the pig iron. Selection of the proper flux for a given process is chiefly a chemical problem requiring a knowledge of the composition and properties of all materials entering the process. Almost all of the slag-forming compounds that enter into a smelting or refining process may bo classed as either 'acicto • or *bases* by virtue of the fact that they will react with each other to form compounds which are similar to the salts formed in reactions taking place in water solutions. Since one of the functions of a flux is to react chemically with unwanted impurities to form a fusible slag, it will naturally follow that to remove »basic1 im- purities, an acid flux will be required and to remove 'acid' com- ponents, a »base« will be used as the flux. *) Acid fluxes; Silica (SiO ) is the only substance that is used as a strictly acid flux. Por this p urpoce it is avail- able as sand, gravel and quartz and aleo ,x: 3iliceou3 iron- bearing minerals, ii) Basic fluxes; The chief nati.„-al basic fluxes are limestone and dolomite (CaCO, and Ca.M/.CO. respectively). Either dolomite or limestone may be used as a blast furnace flux, the proportions of each depending on the other constituents of the slag and the amount of sulphur that the slag remove.

Alumina; Although alumina is seldom employed as a flux, it is present in a large number of raw materials as an impurity and is therefore present in slag. In «lags it may function as an acid or as a base, depending on the conditions. In highly siliceous slags it may form aluminium silicates while in the présenos of an excess of a strong base such as lime, it may form calcium aluminates. Fluorspar; For making slags more fusible, neutral substance like fluorspar (CaF¡>) may be added.

10. Manufacture of Pig Iron;

Pig iron is the term applied generally to the metallic product of the blast furnace when it contains over 90 per cent of iron. This term is used to distinguish it from blast furnace products suoh as 'ferroaanganese* and 'spiegeleisen' that are made from manganese ore or mixture of manganese and iron ores, and still other blast furnace products suoh as 'ferrophosphorus' and 'other ferro-alloys'. Pig iron can be made in the following ways : 1) In blast furnaoe using coke 2) In blast furnaoe -ininj charcoal 3) In eleotric smelting furnace 4) In cupola by melting steel sorap with excess of carbon.

-!.> - 1U -

However, most pig iron is aade in blast furnace using ooke •ad only snail quantities are nade by the other nethods.

10.1 Blast Fornacet The following different produots are produced in blast fornace t i) iron for steel asking ÜJ iron for castings iii) ferro-alloys. The oheaioal speoifioations for the above produots are broadly given in Table 9* - V» -

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«o s IA O m ir\ m « o\»- o ssaa• • • • CM o odd M O O O O a i i i i i 1 a a i o » * IAVO vo «- »- tí £ ro <*v p- o o o• o• o• ï=« >n• r- 1*1 (*1 t- O o o 3 o o o o o o d d d

H S S M gee« 3 ra 3 • n S B i§ ii 3 SEBO o mm IAO o o o O O Q U ! "^ tniTMPi in o. o o o o o • • • a d d d d d d d d d O O O o o IAQ CM ÙSO O IA 888&• • • • IA ï CM «- CM **\ f+\ ro rO 4 iiii 3 i I l 1 • o r~-c\i &88 r-• • O CM O IA •H • í*l • • • • 01 *" ^ d d O T- T- O r- r- IA«- -60 -

In the blast furnace prooess, iron-bearing materials like lumpy iron ore, sinter, pellets, mill scale, open-hearth or Bessemer slag, iron and steel scrap, etc., fuel (coke), and flux (limestone and/or dolomite) are charged into the top of the furnace. Heated air (blast) and in reoent practices, gas, oil or pulverized coal, are blown from the tuyereo. The blast air burncs part of the fuel to produce heat for the chemical reactions involved and for melting the iron while the balance of the fuel and part of the gas from the combustion remove the oxygen combined with the metal. To produce one ton of pig iron, the following materials, on an average, are required : a) Iron ore - about 1.7 tons bj Coke and other fuels - 500 - 660 kg c) Fluxes - 250 - 295 kg dj Scrap - 330 - 340 kg e) Air - 1.8 - 2.0 tons Besides one ton of pig iron produced, nearly 0.2 - 0.4 tons of slag, 2.5 - 3.5 tons of blast furnace gas and about 0.05 tons of flue dust are also produced. 10.2 Changes in conventional blast furnace technology» The depleting world coking coal resources, together with increasing cost of metallurgical coke, has necessitated considerable innovations in blast furnace technology in the recent times. The sharp rise in daily output capability has been accompanied by a steady fall in ooke consumption per ton of iron. The average coke consumption has fallen in the U.K. fro« about 1100 kg to 650 kg per ton, in the U.S.A. from 940 kg to about 6OO kg per ton, and in Japan from 900 kg to below 400 kg per ton. Parallel with the improved fuel efficiency leading to reduoed total coke consumption, there has been realization of the faot that a part of the ooke can be replaoed by hydrocarbon fuel injected at the tuyeres. The various steps taken to reduoe ooke consumption and inorease •etal production are briefly desoribed below t a) Raw materials i) Preparation of iron ore» The current modern praotioe is to use olosely sised lumpy ore of generally 50 mm to 10 mm mise. Studies at Nippon Kokan plant have shown that a \$ deorease of lumps of larger than 35 mm in the burden corresponds to a deorease in ooke rate of about 2 kg per ton and a 1^ deorease of-6 OBI fines leads to a deorease in ooke rate of 1 kg per ton. Larger furnaoes in Japan now use -254-8 mm ore.. It is well known that the iron ore used should be of as high a grade as possible. Experiments in U.S.S.R. have shown that for inorease b y 15t Fe in burden, productivity inoreas« by 2% and ooke rate deoreasejby 3)t. It has also been estimated that for every I5C - 61 -

reduotion in the alumina content of the ore, the coke and flux rates decrease by 40 kg and 60 kg per ton respectively and the consequent increase in production of pig iron made would be about 2.0$; - 1.%. ii) Sinter and its effect: Due to olose sizing of iron ore and limiting the top size of ore for direct charging into the blast furnace, large quantities of ore fines are generated, both at mine sitet, cr.d hot blast temperature, the higher the moisture oontent of the hot blast has to be given to obtain a suitable flame temperature in the hearth zone. The use of very high hot-blast temperatures together with addition of the proper amount of moisture in the blast, has made it possible to increase blast furnaoe production rates substantially. Moisture produces more reducing gas per unit volume than dry air does. However, the possibility of controlling the flame temperature at tuyeres to a certain level by the injeotion of fuel has almost eliminated the necessity of steam addition. The temperature of hot

_ _-. J - 62 - metal has Bince been controlled by fuel injection, in modern practice by the developed oountries like Japan»

c) Oxygen enrichment of blast;

Enrichment of blast with oxygen reduces the volume of gas required at the same daily productivity, ani has therefore an effect identical to the use of a higher top pressure. However, if the blast air is enriched, the flame temperature increases so that with oxygen contents above 2?^, moisture or hydro-carbon fuels must be added to control the flame temperature. It can broadly be assumed that for every one per cent of enrichment a production rate increase of about 3 to 4 per cent can be achieved. The higher the hot blast temperature the smaller the improvement in production rate for each per cent of increase in oxygen content« In Japan's Nippon Kokan's blast furnace oxygen enrichment was first tried as early as 1959« It has been established that one per cent enrichment of oxygen brought about a 5 Per cent increase in production and a slight decrease in coke rate. Nowadays, upto 3«8 per cent enrichment is being adopted. In a 2000 m3 blast furnace in the Soviet Union, oxygen in the blast when increased from 26.7 to 34«7 per cent plus natural gas injection increased from fi.6 to 14.3 per cent, the productivity increased by 15.3 per cent with lowering of coke rate from 484 to 445 kg per ton of pig iron with coke replacement factor by natural gas of 0.91 kg/m3 (Nekrasov et al - Stai »Feb. 1973). In another practice at Magnitogorsk Combine Blast Furnace, Babarykin et al report in»Steel in U.S.S.R.' - March 1976, that with blast containing 25 per cent oxygen and injection of IOO-IO5 ra3/ton of natural gas, it was possible to increase daily pig iron production by 1.8 to 2.2 per cent in the 2014 n>3 blast furnace and a reduction of 2.4 per cent per one per cent of oxygen in coke consumption. With the actual relation between expenditure on coke, natural gas and oxygen, the greatest economic benefit was obtained with oxyeen and natural gas consumption each of 90 nw/ton of pig iron. It has also been established by the above researches that the limiting natural gas consumptions for blast oxygen contents of 21$, 25$, 30$, 35$ and 40^ calculated from practical data are respectively 20-65, 70-140, 100-210, 130-230 and 150-245 np/ton of pig iron. When combined blast is being used to obtain a greater lowering of coke consumption, it is essential to aim for a gas consumption closer to the upper limits and, if to obtain mainly a rise in productivity, one closer to the lower limit.

d) Fuel injection; Fuel injection through the tuyeres is the most important practice next to raw material preparation in blast furnace operation. With the development of means for obtaining higher hot-blast tem- peratures and the need for controlling the flame temperature, it became apparent that cold hydro-carbon fuels could be injected into the blast furnace tuyeres for not only controlling the flame temperature but also to replace some of the coke. 61 -

In the presence of large quantities of coke the hydro- carbon fuels can burn only to carbon monoxide and hydrogen; consequently they produce less heat than that produced by the hot coke they replace.As long as a blast furnace has the stove capacity for obtaining higher hot blast temperature, or aa long as moisture must be added to the blast to lower the flame temperature, hydro-carbon fuels can be used to advantage because their endothermic effect provides a means of controlling the temperature in the hearth. Generally when tuyore-injpcted fuels are used, the moisture content of the blast must be decreased. Natural gas, coke-oven gas, fuel oil, pulverized coal, tar and slurries of oil and coal have been used in this manner. Fuel injection has the following favourable features : Reduction of coke rate Stabilization of blast-furnace operation and ¿i production increase iii) Compensation of shortage in coke oven capacity or saving of coking facilities iv) Low investment in installing the injection equip- ment on blast furnace. For the effective application if fuel injection, attention should be given to the following points : i) Heat compensation capable of keeping the flame temperature at tuyere within a certain range ii) Limit of combustion load for individual tuyeres iii)Lii) Changes in permeability, heat exchange, and re- ducing reactions caused by varying volume of gas produced per ton of hot metal Injection method (engineering of atomizing, etc.) n] Measures to cpoe with unexpected blow-off and other troubles. Heat compensation and combustion load are the most important problems in injecting fuel. Reduction of coke rate brought by the fuel injection is related to the blast temperature. According to the operating results of Nippon Kokan's Kawasaki no.4 blast furnace, the limit of oil injection is 30 kg/ton at a constant humidity, i.e., with a lower limit of 2000°C and an upper limit of 2200°C of the theoretical flame temperature and a blast temperature of 8CO°C. With a blast temperature of 1100°C, even an injection of 110 kg/ton is possible. Limit of the ratio to the amount of oxygen necessary for the perfeot combustion of oil is considered to be 1.1 - 1.2 and thiB would result in a limit of oil injection of 110 kg/ton and that of tar injection of about 90 kg/ton. In recent operations of Nippon Kokan's Fukuyama blast furnaces, oil injection of about 80 kg/ton was applied in combination with oxygen enrichment to reduce the ooke rate to about 400 kg/ton. It was however necessary to keep the theoretical flame temperature at rather a high level of 2300 - 2400°C. It was found to be possible to reduce the ooke rate to 210 kg/ton by injecting reducing gas -64 -

mad« from about 220 kg/ton oil in an experimental blast furnace. Yaro8herskii et al report in «Steel in U.S.S.R. - June 1976» that injection of coal dust in 700 n>3 blast furnace at Donetsk, shows that with 200 kg of lean coal per ton of pig i. ", altered the productivity and coke rates very substantially. Tie data ob- tained over a period of one year aro aB follov.'s : Change in productivity with coal injection - 0.2 per cent Reduction in coke consumption - 45.1 kg/ton of iron Percentual reduction in coke consumption - 7«5 Per cent Reduction in pig iron production cost - about $1.3 per ton of pig iron.

e) High top pressure operation: One of the limiting factors in attempting to increase the production rato of a blast furnace is the lifting effect that is caused by the large volume of gases blowing upv/ard through the burden. This lifting effect prevents the burden from dencending normally and causes a loss rather than an increase in production. Increase in blast volume for raising blast furnace productivity reduces the passage timo of gas through the furnace, i.e., the re- action time. This lowers the utilization ratio of gas resulting in rise in top temperature and increase in coke rate. Pressure drop in the furnace also increases. However, if the blast volume is increased over a certain limit, imbalance of permeability through the furnace would result in channelling and flooding. To achieve a uniform ascent of gases and a satisfactory burden descent, it is necessary to keep the gas-flow velocity within certain limits. Use of higher gas pressure in the furnace leading to a de- creased gas volume is very effective measure for this purpose. Most of the newly constructed furnaces in Japan are operated with high top pressure. Top pressure has been gradually raised to the present level of 1.0 - 1.5 kg/cm2 and some times up to 2.5 kg/cm2 in biggor blast furnaces. According to the results of Nippon Kokan's Fukuyama and other iron producers in Japan, high top pressure operation has the following effects : i) Top pressure and permeability : With the increase in top pressure the permeability index increases proportionately. ii) Effect on production rate : An increase in top pressure raises the productivity; a 0.1 kg/cm2 increase in top pressure corresponds to an increase of about 1.5 per cent in productivity. iii) Effect on coke rate : Increase in top pressure reduces solution loss whereas higher daily productivity results in an increased solution loss but the overall effect is a alight reduction in the coke rate. iv) Decrease in dust loss : A higher top pressure leads to a better permeability and therefore reduces the number of slips. - 6^-

Higher top pressure slows down the top gai velocity, thus reduoing the dust lost.

f) Pre-reduced burden; It has been established by the performance data of blast furnaces that coke consumption reduces and productivity increases when pre-reduced burden is used as shown in Figures 1 and 2 resp. fig. 1. Coke consumption vs. pre-reduced burden.

100

A1* 90 - A •S" CO - • A • • 70 V • ^» • 60 • 4- ^ M — •

40 1 1 I 1 1 1 1 1 1 _l_ 10 30 M 40 BO 00 70 M M 100 METALLIZATION OF BURDEN (%)

• - U.S BUREAU OF MINFSOATA 0.4 • STEEL COMPANY OF CANADA LTD. DATA.

SOURCE: USBM ind Lurgi, Publication No. 1G6

fig. 2. Production vs. pre-reduced burden.

10 20 30 40 60 60 70 BO 80 100 • MET/ ..LIGATION OF BURDEN 1%)

• • U.S. BUREAU OF MINES DATA C\A - STEEL COMPANY OF CANADA LTD. DATA.

' BOURCC: USOM ind Lurgl, Publiutlon No. 160 .J -66-

e) Large Capacity Blast Furnace; Steel making in integrated iron and steel works has been changed from the open-hearth furnace process to the converter process. The high efficiency of the latter process and the ex- pansion of unit capacity of rolling facilities have brought about the most economical annual production unit of iron works. To cope up with thin trend thirds larger facilities and the increasing demand for hot metal from converters, there is a strict requirement for a stable supply of large quantities of low cost hot metal to be produced in blast furnaces having increased capacities. Comprehensive data on factors in operation of larger capacity blast furnace indicate that the production cost of hot metal is lowered. This advantage, though pronounced upto an inner volume of 2500 m , becomes less over the limit of about 40OO m3 as has been studied by the Japanese Iron and Steel makers. In deciding the size of a blast furnace, the properties of raw materials should be seriously taken into account. The require- ments on the burden eize and and the strength have recently become more and more stringent. The blast furnace capacity is increased by enlarging the hearth diameter and other cross-sectional sizes, but not raising the furnace height too much. The top pressure for a larger capacity blast fur- nace is also proportionately increased. Although the operating costs for a larger size blast furnace are higher than for a smaller size furnace, the investment costs are lower in the former case. The overall operating and investment costs are lower than those for smaller size blast furnace. In a larger blast furnace, the solution IOBS is higher because furnace height is not large enough in relation to the increase in inner volume arid hence the descent time for the burden is shortened. The labour cost is reduced with the increase in furnace capacity, but the operating cost of the blower increases accordingly as high top pressure operation is applied for a stable operation. Since the increase in blower operating cost exceeds the decrease in labour cost, the overall operation costs tend to be higher with the increase in furnace capacity. The construction cost per ton of iron is inversely proportional to a third power of the inner volume. This results in the decrease in unit depreciation cost, interest on capital and running cost. The above aspects are diagramatically shown in Pig.3.

U- *> -ö7 _

Piß. 3» Inner volume of blast furnace and running and investment costs (source : UHIDO - ID/WO.146/25)

2030 3000 4000 INNER VOLUME ( MM Pig.4 shovjs the capital coat per ton for different capacity blast furnace.

Pig. 4« Capitai cost per ton - capacity of blast furnace (source : Stali! uni Risen, 90(19/0), No.4)

J 180 Ì 160 i 140 •a •H 1?0

100

Bo

60 45 t/day/m (without counter pressure) 40 60 t/day/nT (oounter pressure 2 at.) 20

0.5 1.0 1.5 2.r, 2.5 3.0 Production capacity in mill, tons/year

___..J -68 -

The Industrial Environmental Reaearoh Laboratory of the U.S. Environmental Protection Agency in a study (EPA-600/7-76-034ot December 1976) has estimated the investment and running costs of a few sizes of blast furnaces in U.S.A. using oxidized and metallized pellets. These figures are given in Tables 10, 11, 12 and 13. Pig.5 shows the relationship between cost of iron making and sulphur in iron produoed.

Pig. 5. Relationship between oost of iron Baking and Sulphur in iron.

•M Mi »M I« M» MM«« CONTINT. I%>

«Mi: 'Ml •»•§ - 69 -

Table 10 t Cost Struoture in New Blast Furnace Facilities

Annual Design Capacity: 1.22 x 106 tons of hot metal Capital Investment: $90 million Location: Oreat Lakes

Units Used ir Costing or Units Con- Annual Cost sumed per Ton t/Pon of Basis t/Ajnit of Product Product

Variable Costs Raw Materials Pellets Btu 0.45 84.7 38.11 Limestone ton 5.OO O.25 1.25 Energy (Details on Table B) Purchased Coke ton 90.25 O.53 47.85 Electric Power Purchased kWh 0.016 25.OO O.40 Energy Credits (Specify form) Blast Furnace 106 Btu 2.0 3.8 (7.60) Water Cooling (Circulating rate) 103 gal O.O5 11 O.55 Labor (Wages) (l) man-hr 7.00 0.15 1.05 Direct Supervisory Wages (s) 1556 labor 0.16 Maintenance Labor and Material yf> CI 3.69 Labor Overhead | 1% (LfS) O.42 Misc.Variable Costs/Credits ( a) Slag Sampling 0.?5 Scrap Credit ton 80.00 0.01 (0.80) TOTAL VARIABLE COSTS 85.33 Fixed Costs Plant Overhead 65* (LfS) 0.79 Looal Taxes and Insurance 2% CI 1.48 Depreciation 18 Tears 4.O6 TOTAL PRODUCTION COSTS 86.21 Return on Investment (pretax) 20* CI 14.76

TOTAL 106.42 -70 -

Table 11 : Cost Structure in New Blast Furnace

Annual Design Capacity: 2.6 x 10 tons hot metal Capital Investment (Cl): $156 million Location: Great Lakes

Units Used in Costing or Units Con- Annual Cost sumed per Ton t/r°n of Basis $/Unit of Product Product

Variable Costs Raw Materials ( a) Pellets ltu 0.45 84.7 38.11 Limestone ton 5.OO O.332 1.66 Energy Purchased Coke ton 90.O O.53 47.70 Electrical Power Purchase^ kWh 0.011! 25 O.40 Energy Credits Blast Furnace Gas 10^ Btu 2.0 3-8 (7.60) Water Process (Consumption) Cooling (Circulating Rate 10^ gal O.O5 11 O.55 Direct Operating Labor (Wages)L man-hr 7.00 0.10 O.70 Direct Supervisory Wages + 15$ labor 0.11 Maintenance Labor and Mat'l.S 5$ Inv. 3.OO Labor Overhead 35$ L+S O.28 Misc.Variable Costs/Credits •lag sampling O.25 •crap credit ton 80.00 0.01 (0.80) TOTAL VARIABLE COSTS 84.36

Fixed Costs Plant Overhead 65$ L+S O.53 Local Taxes and Inaurano« 2$ Inv. 1.20 Depreciation 5*55$ 3.33 TOTAL PRODUCTION COSTS 89.42 Return on Investment (pretax) 20$ CI 12.00 Pollution Control 4.57

TOTAL IO5.99

(») long ton unit - 22.4 lb of ooal oontained Fe. - 71 -

Table 12s Cost Structure in New Blast Furnace (Reduced Coke Rate)

Annual Design Capacity: 2.6 x 106 tons hot metal Capital Investment (Ci): $152 million Location: Great Lakes

Units Used in Units Con- Costing or sumed per Annual Cost ton of I/Ton of Basis «/Unit Product Product

Variable Costs Raw Materials Pellets ltu 0.45 84.7 38.11 Limestone ton 5.OO O.225 1.12 Energy Purchased Coke ton 90.00 O.515 46.35 Electric Power Purchased kWh O.OI6 24 O.38 Energy Credits Blast Furnace Oas 106 Btu 2.00 3.69 (7.38) Water Cooling (Circulating Rate 10^ gal O.O5 10.6 O.53 Direot Operating Labor (Hages) L Man-hr 7.00 0.10 0.70 Direct Supervisory Wages + 1555 Labor 0.11 Maintenance Labor S Maintenance Materials and Supplies 5% Inv. 2.92 Labor Overhead 35*L+S O.28 Mi a 08t8 CreditBl §îaï Sa»Sîng / O.25 Sorap Credit ton 80.00 0.01 (0.80) Total Variable Costs 82.57 Fixed Costs Plant Overhead 65* (L+S) O.53 Looal Taxes and Insurance 2ft Inv. 1.17 Depreciation 18 years 3.25 TOTAL PRODUCTION COSTS 87.52 Return on Investment (pretajt) 20* CI 11.70 Pollution Control 4.O6 TOTAL 103.28

(a) long ton unit > 22.4 lbs of oontained Fe.

J -72 -

Table 13 t Cost Structure in New Sponge Iron (9$ Metallised) Facilities

Annual Design Capacity! 1,200.000 tona Capital Investment! $168 x 106 Looation: Great Lakes

Units Used in Units Con- Costing or sumed per Annual Cost Ton of $/ron of Basis f^Jnit Produot Produot

Variable Costs Raw Materials Pellets ltu 0.45 8.5 38.25 Linestone ton 5.OO O.14O 0.70 Energy (Details on Table B) Purchased Fuel 106 Btu 2.00 Coal ton 25.OO O.625 15.62 Purchased Steam 106 Btu 3.00 Eleotric Power Purohased kWh O.OI8 56.O O.90 Miso. Water Process (Consumption) 10-5 gal O.5O Cooling (Circulating Hate) 103 gal O.O5 0.20 Direct Operating Labor (Wages)(L) man-hr 7.OO 0.20 1.40 Direct Supervisory Wages (s) 15JH. 0.21 Maintenance Materials and Supplie« 4# CI 5.6O Labor Overhead 35# (l*S) O.56 TOTAL VARIABLE COSTS 63.44 Fixed CoBts Plant Overhead 65^ (L+S) 1.05 Looal Taxes and Insuranoe TUf» CI 2.80 Depreciation 18 Years 7.84 TOTAL PRODUCTIOM COSTS 35.83 Return on Investment (pretax) 20£ CI 28.00

TOTAL 102.88 -73 -

Tabi« 14 gives a litt of SOM of the larger sise blaat furnaoes in the world.

Blast furnace« planned or under construction in different countries are listed in Table I5. Those furnaceB which have been commissioned re- cently (since January 1974) are given in Table 16. The operating data of some of the larger blast furnaces in Japan and Soviet Union are presented in Tables 17 and 18 respectivoly. Table 19 gives technical data of a recently commissioned blast furnace at the Lin* Works of Voest Alpine A.C., Austria.

U- - —à - 74 -

Table 14 t Large Blaat Furnaces in the World

Blowing Country in Works No. Hearth Inner Volume Dia.m. m^

1964 Japan Nagoya 1 9.8 2021 1965 Japan Chiba 5 10.0 2142 1965 U.S.S.R. Zidañov 4 10.3 2300 1966 Japan Fukuyama 1 9.8 2004 1967 Japan Wakayana 4 11.0 2535 1967 Japan .Mizushima 1 10.0 2156 1967 Japan Nagoya 2 10.3 2166 1967 Japan Sakai 2 11.2 2620 1967 U.S.S.R. Krivoi Rog 8 11.0 27OO 1967 Netherlands Ijmuiden 6 10.0 2150 1968 Japan Fukuyama 2 11.2 2626 1968 France Dunkirk 3 10.2 2100 1968 Japan Kimitu 1 11.5 2705 1969 Japan Mizushima 2 11.5 2857 1969 Japan Wakayana 5 11.0 2630 1969 Japan Hagoya 3 11.7 2924 1969 U.S.S.R. Cherepovets 4 11.0 2700 1969 Japan Tobata 3 10.5 2338 1969 Japan Fukuyana 3 11.8 3016 1969 Japan Kimitu 2 11.6 2884 1969 U.S.S.R. Nizhnij Tagli 6 11.0 27OO 1969 U.S.A. Burns Harbor 1 10.6 2427 1969 Japan Wakayama 2 10.0 2147 1969 Italy Taranto 3 10.6 2475 1970 U.S.S.R. W. Siberian 2 11.0 2700 1970 Japan Hirobata 4 11.0 2548 1970 W. Germany Ruhrort 6 11.0 2226 1970 Japan Kakogawa 1 11.6 2847 1970 Japan Mizushima 3 12.4 3363 1971 Japan Kashima 1 12.4 3159 1971 U.S.S.R. W. Siberian 3 3000 1971 U.S.S.R. Karaganda 2 11.0 2700 1971 Japan Fukuyama 4 13.8 4197 1971 Japan Kimitu 3 13.4 4063 1972 Japan Oita 1 14.0 4158 1973 Japan Fukuyama 5 4600 1976 U.S.S.R. Krivoi Rog 9 14.7 5000 1976 Japan Kashiaa 3 5050 1976 Japan Oika 2 5OTO •U.S.S.R. Krivoi Rog 15.1 5500

•under oonmtruotion - 75 -

Table 15 s BP planned or under Construction

Capacity Country/Company, Works Date No. Volume m 3 m. l/y

Algeria SMS, El-Hadjar 2 2000 Argentina Propulsora, Enseñada 182 Austria Voest-Alpine, Linz 1976 2400 1.8 Belgium Sidmar, Gent 3 3.7 Brazil Barra Mansa 3 0.13 Cosipa Puacaguera 1975 2 25OO 1.3 CSN, Volta Redonda 1976 3 3200 Cia. Sid. Tubarao 1977 1 45OO Canada Stelco, Nanticoke 1977 1 Colombia Colar, Bogotá 1975/76 2 0.04 Egypt Egyptian Iron + Steel, HeIwan 1575 4 1033 O.65 Finland Rantaruukki, Raahe 19?5 2 West Germany Krupp, Rheinhausen 1976 1.8 Peine-Salzgitter, Salzgitl er 1.8 Italy Piombino 1977 4 Japan mOC, Ohgishima (Keihin) 1976 1 Kawasaki, Chiba 1976/77 6 45OO 3.6 Kobe, Kakogawa 1976A7 3- Amagasaki 3 45OO Nippon Steel, Oita 1975 2 5OOO Kimitsu 4 Tobata 5 Nagoya 1 4000 Sumitomo, Kashima 1976 3 5OOO 4.0

South Korea s% Pohang 1976 2 2254 1.48 Mexico Sioartsa, Las Truchas 1976 1 r'ij 1.4 Ahmsa, Nonolova 1976 5 1.6 Poland Atta Centrum, Kotowice 197* 1 ¿200 Lenin, Nowa Huta 1976/77 2000 6

J -76 -

Tabi* 15 t eontinued

Volume Capaoity Country/Companyt Works Sate Ro.

South Africa Iacor, Vanderbijlpark D Newcastle 1976 2060 1.64 Iacor+Partn ra, Saidanna Bay 182 Sweden Rorrbotten, Tulea 182 3000 2 Spain AHM, Sagunto 182 Turkey Sregii 1975 2 Iekenderu» 1975 1 1386 O.55 U.K. BSC, Redoar 1 4573 3.65 U.S.A. Inland, Indiana Harbor 1978 4000+ Rational, Portage 1976 1 3680 1.80 U.S.Steel, Fairfield U.S.S.R. Ghereporete 5 Karaganda 6 Rovo-Lipetek 1976 6 5000 5.0 West Siberian 4 50OC+ Krivoi Rog 10 Yugoslavia Saederovo 198O 2 1386 -77 -

Table 16 i Recently oommiesioned Blast Furnaoes (January 1974)

No. of Country/Company, Works Hearth Volume Capacity furnace dia.m. 1000 t/y

Argentina Somisa, San Nicolas 2 9.753 4500 1300 Altos Horros Zapla, Palpala 5 5.2 200 Brasil Usiminas, Belo Horizonte 3 11.5 2700 2160 Canada Algoma, Sault Ste. Marie 7 11.7 I8OO Egypt Egyptian Iron + Steel, Helwan 3 1o33 65O France Solmer, Pos 1 10.1 1910 1440 Nest Germany Dillinger, Dillingen 4 10 1790 1000 (later I4OO-I6OO) Duisburger Kupferhütte, Duisburg 5.5 660 200 Italy Italsider, Taranto 5 14 3358 3500 Sweden Surahammar, Spannarhyttan 1 5.5 455 220 U.K. BSC, Llanwern 3 11.2 2289 I8OO U.S.A. Bethlehem, Sparrows Point L 13.716 3681 2880

-J -70 -

Table 17 : Operating Results of Fukuyama, Japan, Blast Furnaoea

1 BF 2 BF 3 BF 4 BF

Blowing in Aug.1966 Feb.1968 Jul.1969 Apr.1971

Inner volume, nw 2004 2626 3016 4197 Hearth dia., m 9.8 11.2 11.8 13.8 Production, t/d 3 4639 6O64 6834 10,017 Productivity, t/d/m 2.32 2.31 2.27 2.39 Coke rate, kg/t 469 469 465 437 Oilrate, kg/t 34 26 40 52 Puelrate, kg/t 503 495 505 489 Sinterrate, y> 70 64 76 80 2 Slag volume, kg/t 53 260 274 290 Blast volume, Nn3/rain 4073 2 5309 5842 7722 Blast pressure, kg/om 2.24 2.61 2 2.93 3.61 Top pressure, kg/cm O.59 0.99 1.36 2.10 Blast temp., °C 1112 1146 1159 1200 02 enrichment, % 0 0 0.6 1*4 Sifa in pig 0.71 O.69 0.66 0.71 336 in pig O.O38 0.037 O.038 O.O32 CaO/SiO? in Blag 1.23 1.17 1.16 1.13 Coke ash, % 9.2 9.1 10.6 IO.5 Drua index 92.4 93.2 91.8 92.0 - 79 -

Tabi« 18 j Data on new Blast Furnace« in U.S.S.R.

3000 m3 BF 5500 m3 BF

Inner volume, m' 5000 5500 Hearth dia., m 14.7 15.1 Useful height, m 33.5 34.3 Sally production, t 12,900 14|000 Burden, kg/t pig iron Sinter 1,000 837 Pellets 680 810 Coke (dry) 375 370 Energy resources, m3/t pig iron c Blast (incl. 6 /o losses) 830 820 incl. process oxygen 158 156 natural gas (incl. # losses) 149 147 Blast volume m3/min 7500 8000 Blast temperature, °C 1400 1400 Tield of smelting products, kg/t pig iron Slag 325 290 Top gas, m3/t 1380 1370 Flue dust 25 25 Manganese in pig iron, $ 1.2 1.2 Sulphur in pig iron, j» 0.035 0.020 Top gas oalorifio value, koal/m3 1190 1180 Top gas pressure, atm. 2.5 2.5 -80 -

Table 19 t Teohnioal Bata - Line Blast Purnao«

Hearth diameter 11 « Total volume 3,055 »3 Utilisable volume 2,504 nß Maximum furnace gas prosaure 2.5 atm. gauge Maximum hot air temperature 1350°C Maximum air quantity 360,000 Nto^ per hour Tuyeres 28 Pig iron tape 3 Slag taps 1 Daily pig iron output 5i500 *»"• Coke consumption per day 2,300 tons Burden rate per day 9»500 tons

U-~ -81 -

10.3 Electric Iron Making Practice»

It was at the end of the last century that the first eleotrio furnaoes were built for smelting iron ore and producing liquid metal. Researches were carried out on three different types of furnaoes : à) the open-bath arc furnaoe iii) the low-shaft or submerged aro furnaoe. A brief description of the above types of furnaces is as follow« : i) Open-bath arc furnace t In these furnaces the electrode is in contact with the slag, but it is not immersed in the solid charge. This type of fur- nace is being used at the Quebec Iron and Titanium Corporation plant at Sorel, P.Q., Canada, for melting of ilmenite with selective reduction of iron and production of a low-carbon hot metal and titaniferous slag. It is also used by the Strategic Materials Corporation forming a part of the Strategio-Udy process. ii) Electric shaft furnaoe ; This type of furnaces built and operated at Domnarvet and Trollhattan, Sweden, and Aoste, Italy, gave no better operating results that the open-bath or the submerged arc furnaoes and hence were finally abandoned. There was not enough gas to pre-heat the charge in the shaft and so indirect reduction of iron oxides by the gas was impossible. iii) Submerged arc furnaces ; This type of furnace is an intermediate type between the shaft and the open-bath furnaces. One of the first such furnaces was constructed by Heroult and used at Sault Sainte Marie, Canada. Later the submerged arc furnace was industrially developed by Tysland and Hole, Norway. There are about 100 electric iron making furnace« with a total capacity of the order of 3 to 4 million tons per year of pig iron. Since the first 600 kw Tysland-Hole furnaoe« at Piskaa and Christiana Spigerverk in Norway, the Bleotrokenisk firm has built a number of larger furnaces. In Norway, four furnaces of 20 - 25 MW of Tysland-Hole type in Moi Rana and one unit of same size in Svelgen are in operation. The larger installations in different countries are given in Table 20. - «2 -

Table 20 : Tysland-Hole Fornácea

Country No. of furnaoes MH

Canada 1 10 Finland 1 10 India 2 20 Israel 2 29 Italy 13 102.5 Japan 2 13 Norway 6 108 Peru 2 20 Phillippines 2 20 Portugal 1 10 Spain 1 6.5 Sweden 6 54 Switzerland 1 8.5 Venezuela 9 180 Yugoslavia 3 30

52 630.5

The Japanese steel works have independently developed eleotrio pig iron smelting furnaces based on relatively snail open furnaoes of 1 to 10 MH capacities. Host of the units in operation smelt the locally avail- able beaoh sand concentrates. Including the Japanese furnaces and also the smaller open type of furnaces, the total smelting capaoity is estimated at approximately 1000 HW producing 3 to 4 million tons of pig iron annually. Consumption of eletrical energy has averaged about 2200 kwh per ton of nig iron produced and electrode paste consumption between 8 and 15 kg/ton. About 1500 kg of sintered ore and 400 - 430 kg of coke are generally oonsumed to yield one ton of pig iron. 10.4 Pre-reduced Iron Ore Pellets for Smelting! In the field of direot reduotion processes a clear distinction exists between (a) pre-reduced material for iron smelting in blast furnaoe or electric furnace or (b) sponge iron for direct steel making in eleotrio furnaoe. In the former caseythe endproduot is pig iron. A brief review of the use of pre-reduced material for pig iron making is made in the following lines t Sinoe considerable pre-reduotion takes place in the shaft of the blast furnaoe itself, the advantages of using a pre-reduoed oharg« are not quite significant in blast furnaoe. -Hi -

On the other hand use of pre-reduced charge for eleotrie •melting results in substantial economy in consumption of coke, electrical power and fluxes. The productivity also tends to improve with the use of pre-reduced charge. The extent of improvements de- pends upon the degree of metallization of the pre-reduoed iron ore. Of the large number of processes for pre-reduction and sponge making the following are the most promising ones : i) Solid reducíante : External heating - (a) Echeverría ib) Kinglor Metor Internal heating - (a) Krupp (b) SL/RN ii) Gaseous reductants : Shaft furnace - (a) Midrex (gas recycling) Purofer (gas recycling) ft! Armco (no gas reoyoling) Fixed bed - ityL Pluidized bed - (a.) HIB (under pressure) (b) FIOR (under pressure) (c) Novalfer (without pressure)

The prooesses in commercial production are briefly as follows : Rotary kiln process; This process uses non-coking coals as the re- ducing agent and is a continous one. It is advantageous to those countries where coal is available in abundanee along with good quality iron ore. Both, high grade lumpy iron ore or high t/rad pellets can be utilized. Midrex process ; This process uses a continous shaft furnace using re- formed natural gas as the reducing agent. The recycling of gases together with the advantages of a continous process results in low energy require- ments.

HYL process j This is a batch prooess using a fixed bed reaotor and uses reformed natural gas as the reducing agent. Arnco Process i This process is similar to the Midrex prooess. HIB process ; The high iron briquette prooess is a fluidized bed reduotion one using Bteam-reformed natural gas. The fine ore is first pre-heated, then reduced by steam-reformed natural gas at a temperature of about 7O0°C followed by hot briquetting and cooling.

11 • Economic Considerations of Iron Making Prooesses ;

In comparing the capabilities of eleotrio reduotion furnaces and blast furnaces it is difficult to oonoeive of an electric furnace plant having an iron-making capacity of 2 million tons or more; here is „he domain of the blast furnace with its large output. Por plants of about 1 million tons capacity the electric reduction furnace could be con- sidered» and for plants of less than one-half million tons capacity. The electric furnaces would offer the advantage of greater flexibility than a - Pa-

lar ge blast furnace. It may, hov/ever, be noted that the trend toward larger eleotrio furnaces employing pre-heated and pre-reduced charges will make possible the production of 50O tpd per furnace in the near future and with possibilities of higher tonnages of upto 1000 tpd. Such furnaces could be considered for I.5 million tons plants, such as thone projected for eastern Siberia or Africa where tremendous hydro-electric potentials exist in equatorial regions. Concerning cpaital costs, there does not appear to be a great deal of difference between blast furnace and electrio-reduction furnace plants of comparable capacity. Por large - or medium - size plants costs per annual ton of iron capacity for either a modern blast furnace or an electric-reduction-furnace installation, each with ore preparation but without stocking facilities, coke-oven plants, power stations and mines, may be more or less equal. If investment costs are comparable for blast furnace and electric furnace installation, then the choice between them is largely a matter of the relative cost of electrical eneergy and the cost and availability of coking coala. Studies in Soviet Union have shoen equivalent costs for the two processes when 1 kg of coke h.td equivalent value to 3*5 to 4 kwh employing 108,000 - 120,000 kva furnaces with six electrodes with an output of 1000 tpd. In conclusion it may be pointed out that choice between +he two prooesses would mainly be dependent on availability of cheap electrical energy and that of coal. Since developing countries have a dominant share of world resources of gas, oil and hydro-' ' "etric energy potential, and a good share of iron ores, they suffer a lack of coal, particularly coking coal. It would, therefore, be more desirable for many developing countries to consider adoption of electric furnace method which has the added advantages of flexibility of size and comparatively lower plant costs. The substitution of charcoal for coke is an acceptable and fully feasible technolo^r. However, its utilization will call for a pro- gramme of reforestation in order to ensure adequate supplies of char- coal on long term basis. The paramount importance of preserving en- vironmental balance in developing countries can not be overlooked by delaying the replantation programme.

12. World Production of Pig Iron;

World's pig iron production and its output per capita are shown in Table 21. The data has been published in Metal Bulletin - June 10, 1977.

J -ö5 -

Table 21 : Pig Iron Production

Production x 000 tons Output per capita kg f> World Country —- 1975 1976 1975 1976 Output 1976

Europe

West Germany 30,074 31,849 486 517 6.53 Belgium 9,180 9,956 938 1,014 2.04 Prance 17,921 19,035 338 357 3.9O Italy 11,412 11,694 204 208 2.4O Luxembourg 3,889 3,756 10,655 10,151 0.77 Netherlands 3,970 4,266 291 310 O.87 Denmark - — _ U.K. 12,131 13,859 217 248 2.84

EEC 88,577 94,415 343 364 19.35 Finland 1,368 1,240 290 260 O.25 Norway 638 630 159 156 0.1} Austria 3,056 3,325 406 444 0.68 Portugal 327 350 37 39 0.07 Sweden 3,309 2,600 404 315 0.51 Switzerland 35 35 5 5 0.01 Spain 6,842 7,000 193 196 1.43 Turkey 1,337 1,350 34 34 O.28

W.Europe 105,489 110,945 276 289 22.74

East Germany 2,456 2,460 146 147 O.5O Bulgaria 1,509 1,600 173 183 0.33 Yugoslavia 2,001 1,950 94 91 O.4O Poland 7,752 7,900 228 230 I.62 Rumania 6,602 6,650 312 312 1.36 Czechoslovakia 9,290 9,400 629 634 1.93 Hungary 2,219 2,200 211 208 0.45

Europe 137,318 143,105 268 278 29.33

U.S.S.R. 102,968 105,500 405 411 21.62 Asia Taiwan 470 550 29 34 0.11 China 22,500 23,000 27 28 4.71 India 8,353 8,730 14 14 1.79 Japan 86,877 86,500 793 757 17.73 N. Korea 3,100 3,100 195 191 0.64 S. Korea 1,194 1,500 36 44 0.31 Thailand 40 40 1 1 0.01

Asia 122,534 123,420 56 55 25.30 - 86 -

Table 21 t continued

Production x 000 tons Output per capita kg i» World Country 1975 1976 1975 1976 Output 197

America Argentina 1,038 1,100 41 43 0.23 Brazil 7,260 7,700 68 70 1.58 Chile 417 400 41 40 0.08 Canada 9,150 9,750 401 421 2.00 Colombia 297 260 12 10 O.05 Mexico 2,961 3,000 49 48 0.61 Peru 307 220 19 13 O.O5 Venezuela 535 48O 45 39 0.10 U.S.A. 72,505 79,150 339 368 16.22

America 94.47U 102,060 170 180 20.92 Africa Egypt 250 25O 7 7 O.05 S. Africa 5,197 5,720 204 215 1.17 Rhodesia 310 310 48 46 0.06

Africa 5,757 6,280 13 15 1.29 Australasia Australia 7,476 7,500 553 548 1.54

Australasia 7,476 7,500 356 352 1.54

WORLD 470,500 487,900 119 122 100.00 - 87 -

TCCHMOIOOICAL PROFILE

OM

STEEL MAKIHO - 88 -

O 0 H T E KT S

Mo. Page No.

1. Introduction 09 2. Processes 85 2.1 Open Hearth 89 2.2 Pneumatic 90 Bottom-blown Converter 91 Side-blown Converter 92 Stora-Kaldo 92 Rotor 92 LD 92 OBH 1(6 LWS 1C7 Q-BOP 107 SIP 108 2.3 Continuous Processes 112 IRSID 112 HORCRA 112 HEARTH 112 BISRA 112 NRIH 112 2.4 Electric Processes 113 Open Bath 113 Shaft 113 3ubmer/?id Aro 114 U.H.P. Furnace 114 2.5 Atomic Energy and Steel-making 114 2.6 Share of each Process in Stool Production 115 3. P&ctors affecting ProceRs Seleotion 120 3«1 Optimum Works Scale 120 3*2 Cost Data 121 4« World Steel Production 130 - V) -

1. Introduction;

Pig iron consists of the element iron combined with numerous other chemical elements, the most common of which are carbon, man- ganese, phosphorus, sulphur and silicon. Depending upon the com- position of the raw materials used in ironmaking - principally iron ore (beneficiated or otherwise), coke and limestone - and the manner in which the furnace is operated, pig iron may contain 3.0 to 4.5 per cent of carbon, O.I5 to 2.5 per cent or more of manganese, as much as 0.2 per cent of sulphur, 0.025 to 2.5 per cent of phosphorus and 0.5 to 4.0 per cent of silicon. In refining pig iron to convert it into steel all five of these elements must either be removed almost entirely or at least reduced drastically in amount.

Modern steelmaking processes, including the pneumatic processes, are divided into two general classes from the chemical standpoint : acid processes and basic processes. Carbon, manganese and silicon can be removed with relative ease by any of the processes, either acid or basic. The removal of phosphorus and sulphur requires special conditions that can be met only by the basic processes wherein lime is added to the chemical system to form a basic slag that is capable of forming compounds with phosphorus and sulphur during refining operations, thereby removing them from the metal.

2. Processes;

There are five different processes of steelmaking with several modifications in each of these : 2.1 Open Hearth processes 2.2 Pneumatic processes 2.3 Continuous Steelmaking processes 2.4 Electric Steelmaking processes 2.5 Atomic Energy and Steelmaking

(2.l)0pen Hearth processes;

The open hearth furnace is both reverberatory and regenerative. The charge is melted on a refractory hearth, which is shallow in re- lation to the length of the hearth by a flame passing over the charge •o that both, the charge and the relatively low roof above the hearth, built of refractory brick, are heated by the flame. The hot gases from the combustion of fuel pass out of the reverberatory furnace chamber through passages into regenerative chambers containing fire brick.

There are two types of open hearth processes :

(a) Acid open hearth process ; The hearth of the furnace is of acid brick construction. The initial charge consists of cold pig iron or oold pig iron and scrap. No ore can be added with the charge for iron oxide being a base, would react with the acid refractory lining and destroy it rapidly. Por the same reason the melting of scrap alone would be undesirable for its oxidation products would have a simüa detrimental effect.

J - 90 -

In this procesa only silicon, manganese and carbon are eliminated and only a trace of phosphorus and none of the sulphur are eliminated. In faot the finished steel may contain a slightly higher percentage of both of these elements than the average of the charge. The specifications for acid open-hearth pig iron usually desire t Silicon - less than I.5 per cent Manganese - 1.0 to 2.5 per cent P and 3 - under 0.045 per oent C - 4*15 to 4*40 per cent The composition of acid open-hearth slag is generally as follows 1

Si02 - 52 to 56 per oent FeO - 2O.5 to 29 H MnO - 10 to 2O.5 •• P20,- - 0.02 to 0.045 " AI2B3 - 3.1 to 4.2 •' CaO - O.7 to 5.4 " NgO - 0.12 to trace " (b) Basic open hearth process t The hearth of the furnace for the basic process is linod with baBic refractory material like magnesite and burned dolomite to permit charging of limestone and use of a basic slag for re- moval of phosphorus and sulphur. The specifications for basic open-hearth pig iron usually are t Silicon - under 1.5 per cent Manganese - 0.4 to 2.0 per oent Sulphur - under O.05 per oent Phosphorus - under 0.9 per oent Carbon - 3»5 to 4*40 per oent The operation of basic open hearth process has undergone ohanges during the oourse of time. The earlier "ore praotioe" has been ohanged to "oxygen roof lance practice". The use of oxygen increases flame temperature and the rate of heat transfer to the charge, thereby speeding up melting of high sorap charges. It also compensates for deficiencies in air supply and regenerator oapaoity. In modern oxygen roof-lance practioe, the flow of oxygen to the furnace is begun immediately after the addition of hot metal and is continued throughout most of the refining period. It has been reported that there is a saving in heat time of 10 to 25 per cent and a decrease in fuel consumption of 18 to 35 per oent when oxygen roof-lancing is adopted. (2.2) Pneumatio processe«t In oonmon with other steelmaking methods there are two ohemioal types of pneumatio processes - aoid and basic. In both types air, high- purity oxygen or combination of these and other oxidising gases are blown under pressure through« onto or over the surface of molten pig iron to produce steel. If air is used for blowing its nitrogen content serves no useful purpose and actually removes heat from the system. -tu -

Nitrogen absorbed during blowing is considered a« an undesirable impurity in the finished steel.

There are several ways in which the oxidizing gas can be supplied to a pneumatic process :

(i) Bottom-blown Converter;

The bottom-blown converter had been the principal type used in both, the acid and basic air-blown pneumatic processes for steel production. The blast travels full length of the molten bath, thus representing the extreme of submerged blowing practices.

The bottom-blown acid process known as acid Bessemer process, earlier produced the majority of the world's steel supply. Iron of the correct chemical composition and temperature is required for the procesa conforming, generally, to the following composition : Silicon - 1.1 to 1.7 per cent Manganese - 0.4 to 0.7 per cent Phosphorus - 0.09 per cent max. Sulphur - 0.03 per cent max. Carbon - 4«0 to 4-5 Per cent The blow to produce steel lasts for a period of only 10 to I5 minutes and speed of operation is ve-y rapid. The ratio of silicon f to manganese in pig iron 3hoild be 7 ,o ?-jt aa the former is a source of heat. Oxygen enrichment of air-bl?;3t helps in reducing blowing time and permits greater utilization of --:>lñ iron and scrap.

Bottom-blown basic process known as basic Bessemer process or Thomas or Thomas-Gil chinst process was never extensively adopted in view of the development of the basic open-hearth process.

A typical blast-furnace iron for bottom-blown basic Bessemer process generally contains : Silicon - 0.2 to 0 •5 per cent Manganese - 0.6 to 1 .0 11 Phosphorus - I.4 to 2 .0 •• Sulphur - 0.03 to 0 .05 •i The chemical composition and properties of steels produoed by this method more closely approach the composition and properties of basic open hearth steels of similar grade than do comparable steels.made by the acid Bessemer process. Bat the nitrogen content of the bottom-blown basic pneumatic steels is definitely higher than that of basic open-hearth •tesi. Por this reason, the properties of air-blown steels made by the basic Bessemer process, while more similar to basic open-hearth steels than are acid Bessemer steels, are still inadequate for certain applications because of their higher strength, lower ductility and susceptibility to strain aging.

1.0 7 I- 12.2 m ! 2.0 I.I

11.25 1.4 111.6

MICROCOPY RLSOLUIION ltSI CHAR!

N.MmNAl HlllílAII ni -,UMüH:>. ••« • A -•»2 -

(ii) Side-blown Converter!

The chemical reactions which occur in the side-blown acid con- verter are similar to those occuring in the bottom-blown acid con- verter. However, in the former, all the tuyeres are above the liquid level of the batn and entering through the side of the vessel. The steel produced 's much hotter from a similar iron charge than pro- duced by the acid bottom-blown converter, and thus silicon content of the iron can be somewhat lower. Nitrogen content of the finished steel is obviously much lower than in the steel made by the bottom- blown acid process. By enriching the air blow by oxygen, the blowing time is reduced.

(•i.ii) Stora-Kaldo process;

In this process oxygen is introduced at an angle with respect to the surface of the liquid metal bath contained in a tilted, rotating vessel. In contrast to bottom-blown Bessemer vessels and top-blown oxygen vessels, the Kaldo furnace is tilted at about I5 to 20 degrees from the horizontal while operating and can be rotated about itB longitadinal axis at speeds upto 30 revolutions per minute.

As in all top-blown pneumatic processes, phosphorus is eliminated simultaneously with carbon, unlike in the basic Bessemer process where it is eliminated only after all the carbon has been removed.

(iv) Rotor Process;

The process developed in Oberhausen, PRO., and often referred to as Oberhausen process, employs the same rotary principle as the Kaldo procese except that the speed of rotation is -^ to 2 revolutions per minute. Another distinct feature is that two oxygen lances, one for high purity oxygen and the other for commercial variety of oxygen, are used. Tap to tap time for a 66 ton vessel is about 2 hours.

(v) LP Process;

In the basic oxygen process, substantially pure oxygen is intro- duced from above the surface of the bath in a basic-lined vessel. The LD process (Linz-Donawitz process) was developed in Austria and was initially designed to employ pig iron produced from local ores that are high in manganese and low in phosphorus contents. The basic oxygen process has readily been adapted to the processing of pig iron of medium and high phosphorus contents. The phenomenal growth of the LD process out-stripped steel production by the basic open-hearth process. All grades of steel including high carbon, low alloy and stainlesB, are now being produced by LD process.

The process has been extensively employed, particularly in Japan, USA and Europe. Continued improvement in this technology has enabled reduction of heat time to 30 to 40 minutes from earlier time of 50 to 60 minutes. This has been mainly possible due to intensified oxygen -23 -

blowing rate and use of multi-hole lance. A 400-ton converter at August-Thyssen-Htttte employs a 7-hole lance oapable of blowing about 1,4000 cubic meter of oxygen per minute. The tap to tap time is about 35 to 40 minutes. To enable higher scrap usage in the LD process from the normal 20 to 30 per cent to 40 to 50 per cent, pre-heating of the scrap by oxy-fuel lance and using of silicon carbide and calcium carbide have been adopted. Continuous improvements in the quality of refractory lining have increased lining life of 400 to 80O heats to, in some cases, upto about 2000 heats. Besides the quality of lining and use of dolomitic lime as part of the flux charge improved operating tech- niques and control of silicon content of the hot metal have influenced the lining life. -94 -

Table 1 shows a list of LB installations in the different countries.

Table 1 : World LD steel capacity

No. of Conver- Annual capacity (mill. Company ters output m.tons raw steel) L/D plant per heat (tons Start up Existing To be location raw steel) date added

ALGERIA SNS: El-Hadjar 2x65 1972 0.45 3x85 1979 1.30 Siderurgie Ouest 1983/88 10.00 TOTAL 0.45 11.30

ARGENTINA Soraisa: San Nicholas 2x170 1973 1.60 1x170 1977 1.25 TOTAL 1.60 I.25

AUSTRALIA BHP: Newcastle 2x220 1962 2.35 1x55 1967 0.35 1x70 1981 O.25 2x225 1986 2.00 Whyalla 2x120 1965 1.24 Port Kembla 2x260 1973 2.78 Kwinana 1x65 1981 O.56 TOTAL 6.72 2.81

AUSTRIA Linz 3x35 1952/56 0.60 3x55 1959/68 I.JO Voest-Alpine 2x145 I973A6 2.00 Donawits 3x65 1953/74 1.30 TOTAL 5.2O

BELGIUM Cookerill: Chertal 3x165 1963/68 2.5O Seraing 2x225 1965 2.00 Marchienne 1x40 1965 0.20 1x70 1973 0.45 Forges de Clabecq: Tttre 2x83 1964/69 1.30 Sidmar: Gent 2x285 1967 3.20 Hai naut-Sambre: Mont igni es-sur-Sarabre 3x180 I969A2 3.5O Boel: La Louviere 3x85 1967/71 2.00 TOTAL 15.15 "95 -

Table 1 : oontinued

No. of Conver- Annual capacity (mill. Company ters output m. tons raw steel) LTD plant per heat (tons Start up looation raw steel) date Existing To be added

BRAZIL Acesita: Timoteo 1x35 1972 0.18 1x80 1978 O.38 2x80 O.78 Belgo-:«ineira: Joao Moni evade 2x40 1957 O.5O Siderurgica 0.10 Hannesmann: Belo Horizonte 2x30 1963 O.40 1.00 Volta Redonda 2x200 1977 2.48 CSM: 1x200 1980 2.12 Piacuagera 3x85 1.50 Cosipa 1965A7 3x120 1978/80 I.80 Siderurgica Tubarao: Tubarao 2x300 1980 Barra Nanea] 2.7O Barra Mansa 2x15 1971 0.12 Ueiminasî Ipatinga 3x80 1963A3 1.60 2x160 1973 0.60 TOTAL 7.38 8.92 BULGARIA Kremikovtsit Kramikovtsi 3x100 1966 1.70 TOTAL 1.70 CANADA Al goma Saulte Ste. Marie, Ont. 3x100 1958/64 1.32 2x227 1973 2.54 Hamilton, Ont. 3x150 1954/66 2.80 Dofaaoot 1x300 1977 1.20 Hamilton, Ont. 3x127 Stelco: 1971 2.54 Nantiooke, Ont. 2x227 I960 1.18 TOTAL 9.20 2.38 CHILE Cap: Talcahuano 2x110 1976 1.10 0.91 TOTAL 1.10 0.91 CHINA Maanshani Naanshan, Aimai 5x- 1970 San-mingt San-ming, Fukien 3x6 1970 • - 96 -

Tab] e 1 : continued

No. of Conver- Annual capacity (mill. Company ters output n. tons raw steel) L/C plant per heat (tona Start up location raw steel) date Existing To be added

CHINA, cont. Capital: Shih-Chingshan, Hopei 3x30 1965/66 O.50 Hantan: Hantan, Hopei X Wu-Han: Wu-Han, Hopei 1x- 1970 Lierçyuan: Lienyuan, Hunan 1x- 1969 Huhehot: Huhohot, Inner Mongolia x Paotou: Paotou, Inner Mongolia 2x- 1970 0.50 Nanking: Nanking, Kiangsu X Liu-Chow Municipal Poundr v: Liu-Chovj, Kwanfjsi 3x- 1970 Canton: Canton, Kwangtung 2x- 1969/70 Hainan: Hainan, Kwangtung 1x- 1970 Anshan: AnBhan, Liao-ning 2x(lge) I.50 Shanghai : Shanghai, Shanghai 3x35 1966 O.4O 1x120 1970 0.70 Tai-Yuan: Tai-Yuan, Shanai 2x55 1969 Yen-T »ai: O.55 Yen-T»ai, Shantung 1x- 1968 Si an: Si an, Shcnhai 1x3 1970 Kunming: Aiming, Yunnan 1x- 1970 TOTAL 4.15 TAIWAN China Steel Corp. Kaohsiung, Taiwan 2x150 1977 I.50 TOTAL I.50 CZECHOSLOVAKIA East Slovak: Kosioe 3x110 1966/67/80 2.20 O.80 2x150 1974 1.50 TOTAL 3.7O O.80 EOTPT Egyptian Irorw-Steel: Helwan 3x70 1974/76 1.20 • TOTAL 1.20

J

à -37 -

Table 1 : continued

No. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up looation raw steel) date Existing To be added

FINLAND Koverhar: Lapp oh .ja 2x50 1971 O.55 Rautaruukkii Raaho 3x75 1967/76 1.60 TOTAL 2.15 FRANCE Aciérie do Marpent et Hydraul i due du Nord: Marpent 1x3 1961 0.01 Aciéries du Furan: Saint Ktienne 1x2 1962 0.02 Cockcrill: Rehon 1x30 1963 0.16 Creusot-Loire Usine des Dunes: Dunkerque 1x60 1971 0.40 Pont-a-Mou3son: Fumel 1x2 1963 0.01 Sté Métallurgique de Normandi e: Mondeville 1x65 1967 O.4O 2x85 1977 1.00 Sté. Nouvelles des Aciéries de Pompey, Pompey 2x85 1964 O.6O Sacilor: Gandrange 2x250 1971 2.5O Solmer: Foo-sur-Her 2x200 1974 3.5O Usinor: De nain 4x60 1964A1 I.80 Dunkerque 3x160 1962 3.5O 3x220 1972 4.5O TOTAL 17.40 1.00

NEST GERMANY Dillinger: Dillingen, Saar 2x200 1968 2.00 Thyssen AG: Beeckerwerth 3x255 1962 6.60 Bruckhausen 2x385 1969 5-45 Ruhrort 4x125 1962/68 4.3O Thyssen HenrichshUttat Hattingen 1x150 1970 1.^.0 Krupp: Rheinhausen 2x300 1975 3.00 3x115 1964/67 2.00 - yò-

Table 1 : continued

No. of Conver- Annual oapacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

HEST GERMANY, cont. Hoesch: Dortraund-Hoerde 3x180 1963/66 4.20 Kloeckner: Bremen 2x275 1968 3.60 Mannesirann: Dui sburg-Huc ki ngen 2x220 1966 2.76 0.24 3x50 1967 1.20 Rheinstahl : Hattingen see Thyssen Henriohshtttte above Pe i ne-Salzgi 11 er: Peine 3xbv, 1964 1.91 Salzgitter 3x210 1968/n 4.50 Roechling-Burbaoht Burbach, Saar 2x110 1972/75 2.50 Volkingen, Saar 3x140 1980 2.30 TOTAL 45.52 2.54 GREECE Halyvourgikii Efesia 2x45 1963 0.45 2x45 1970 0.45 TOTAL 0.90 HUNGARY Danube: Dunaujvaros 2x110 1979 1.10 TOTAL 1.10 INDIA Bokaro: Bokaro Steel City, Bihai 3x100 I973A6 1.28 2x100 4.00 2x300 Hindustan: Rourkela 3x50 1959/60) 1.60 2x60 1966/67) Maharashtra Elektrosmelt: Chandrapur, Maharashtra 2x15 1978 0.15 Vievesvar ay a: Bhadravati 2x15 1965 O.O8 0.03 TOTAL 2.96 4.18 IRAN NISC: Aria Mehr 3x100 1972/76 2.00 TOTAL 2.00

_..vf - yi -

Table 1 : continued

No. of Conver- Annual capacity (mill. Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

ITALY Piombino: Piombino 3x100 1970 1.50 O.5O Italsider: Bafc^oli 3x150 1964 2.40 Taranto 3x310 1964 4.70 3x350 1973 5.80 Cogne: Aosta 2x60 1970 0.?2 TOTAL 14.62 O.5O JAPAN Kawasaki : Chiba No. 1 2x85 1970 1.15 Chiba No. 2 3x150 1962/65 4.?6 Mizushima No. 1 3x180 1967/69 4.9O Mizushima No. 2 3x250 1970/73 7.40 Kobe: Kobe 3x80 1961/66 2.30 Amagasaki 2x40 I960 OJO Kakogawa 3x23? 1970/73 6.00 3.00 Nakoyama: e Funamachi 2x6 , 1975 O.9O Mizuo 3x90 1960/62 1.65 NKK: Fukuyama No. 1 3x200 1966/68 5.5O Fukuyama No. 2 ?x275 1969/71 7.60 Fukuyama No. 3 3:330 1973 4.40 Ogi anima 3x275 1976/79 3.00 3.00 Nippon Steel: Yawata No. 1 1x150 1974 1.50 Yawata No. 2 3x150 1962/70 4.30 Yawata No. 3 2x75 1966/67 2.00 Yawata No. 5 2x60 1957/64 O.7O Muroran No. 1 2x50 1964/67 0.60 Muroran No. 2 3x110 1961/67 3.60 Muroran No. 3 2x270 1977 2.6O Kamaishi 2x90 1965 1.40 Hirohata No. 1 2x100 1960/65 1.50 Hirohata No. 2 3x100 1968/73 2.7O Nagoya No. 1 3x160 1964/67 3.8O Nagoya No. 2 2x250 1969 3.20 Sakai 3x170 1965/67 4.5O Kimitsu No. 1 3x220 1968/09 V9C Kiaitau No. 2 2x300 1971 ••.f. ) Oita 3x340 1972/76 , v. Tokai Special Steel: Hagoya 2x75 1968 0.ÖÖ - IOC

Table 1 : continued

No. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

JAPAN, cont. Nisahin: Shunan 2x45 1970 0.33 Kure 3x90 1965 2.70 1x150 1977 2.60 03aka Iron + Steel: Ninnijima 2x40 1964 O.5O Sumitomo Metal Industries: Kokura No. 1 2x70 1961 1.04 Kokura No. 2 3x70 1970/76 2.O8 Wakayama No. 1 1x70 1968 O.6O Wakayama No.2 3x160 1963 3.83 Wakayama No. 3 3x160 1967 4.64 Kashima No. 1 3x250 1971 6.00 Kaahima No. 2 2x250 1974 3.00 TOTAL 122.78 11.20 LUXEMBOURG Arbcd: Dudelange 1x77 1962 0.98 Eoch-Schifflange 1x80 1976 0.96 1x80 1978 O.96 Esch-Belval 2x150 1976 2.00 Differdange 1x160 1973 2.10 Rodange-Athus: Rodange 1x25 1965 0.10 TOTAL 6.14 0.96 MALAYSIA Malayawata: Prai/Penang 2x15 1967 O.I8 TOTAL O.I8 MEXICO Ahmsa: Monclova 3xfl0 1971/74 I.40 1x125 1976 O.8O Fundidora Monterrey: Monterrey 2x150 1975 I.50 Sicartsa: Lazt.ro Cardonas, Mi oh. 2x100 1976 1.30 2x200 1979 2.35 1x200 1988 2.35 1x100 1990 1.30 TOTAL 5.OO 6.00 MOROCCO Sonasid: Nador 2x105 198O 1.00 TOTAL 1.00 -101 -

Table 1 : continued

No. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

NETHERLANDS Hoogovens : Umiiden 3x100 1958/61 2.45 3x300 1968/76 4.7O TOTAL 7.15 NORWAY Norsk Jernverk: Noi Rana 2x70 1976 0.70 TOTAL 0.70 PERU Siderperut Chimbóte 2x35 1966 0.33 2x180 1982 I.80 TOTAL 0.33 I.80 PHILIPPINES National Steel Corp.: Iligan City 1x25 1979 0.12 Tagoloan, Misamis Or. 2x200 1982/83 2.00 TOTAL 2.12 POLAND Huta Im. Leni na î Krakow 3x120 1966/n 3.5O Katowice: Katowioe 3x350 1976/79 4.5O 4.00 TOTAL 8.00 4.00 PORTUGAL Siderurgia Naoional: Seixal 2x45 1961 O.5O TOTAL O.5O RUMANIA Oalati: Galati 3x150 1968/69 3.5O 3x150 1975 3.5O 3x150 1979/80 3.5O TOTAL 7.00 3.5O SOUTH AFRICA Highveld: Hitbank 2x60 1968 O.6O 3x60 1977/7<8 Isoor: 0.7$ 2x300 1987/88 3.00 Newcastle 3x150 1974A5 2.8O •andarti jlpark 3x150 I974A5 3.29 3x150 1985/86 Pretoria 3.29 3x160 1990/91 3.5O TOTAL 6.69 10.54 - 102 -

Table 1 : continued

No. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

SOUTH KOREA Pohang: Pohang 3x100 1973/76 2.20 TOTAL 2.20

SPAIN AHV: Sestao 3x70 1967/69 1.50 Sagunto 3x40 I969A6 1.00 Avi 1 es 3x65 1966 1.45 Ensidesa: 3x100 1969/- 1.20 1.13 Gijon, Verina 3x125 1971 2.43 TOTAL 7.58 1.13

SWEDEN Fagersta: Fagerata 2x40 1962/69 0.17 Granges : Oxelosund 1x180 1977 1.80 Norrbotten: Lulea 2x105 1972/75 1.80 TOTAL 1.97 1.80

TUNISIA Elfouladh: Menzel-Bourgiba 2x15 1965 O.I8 TOTAL O.I8

TURKEY Eregli: Eregli 3x90 1965/76 I.8O Turkiye Demir ve Celik Isletmeleri: l8kendcrun 3x130 1977/80 1.10 1.30 Karabuk 2x100 I98O 1.00 TOTAL 2.9O 2.30

UNITED KINGDOM BSC, General Steels: Scunthorpe 3x300 1973 4.5O Normanby Park, Scunthorpe 2x85 1964 1.Ò0 BSC, Teeside: Consett 2x165 1968/73 1.30 Lackenby 3x260 1971/72/- 2.11 2.56 BSC, Scottish: Motherwell 2x125 1964/- 1.20 2.00 BSC, Welsh: Ebbw Vale 3x50 1963 O.7O Llanwern 3x170 1962 3.5O Port Talbot 2x320 1969 3.00 1981/85 3.00 - 103 -

Table 1 : continuad

Ho. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

UNITED KINODOM, cont. BSC, Tubes: Corby 3x130 1965 1.30 TOTAL 18.61 7.55 USA Alan Wood: Conshohocken,Pa. 2x150 1968 1.25 Allegheny Ludium: Matrona, Pa. 2x80 1966 0.60 Anaco: Aahland, Ky» 2x180 1963 2.00 Middletown, Ohio 2x210 1969 2.00 Bethlehem: Lackawanna, N.Y. 3x300 1964/66 4.70 Sparrow Point, Md. 2x215 1966 3.20 Bethlehem, Pa. 2x270 1968 2.70 Burns Harbor, Ind. 2x300 1969 4.30 1x300 1978 1.00 Johnstown, Pa. 2x200 1978 2.30 CP + I: Pueblo, Colo. 2x120 1961 1.30 Crucible: Midland, Pa. 2x105 1968 0.90 Ford Motor: Dearborn, Mioh. 2x250 1964 2.90 Inland: East Chioago, Ind. 2x255 1966 4.00 2x210 1974 2.20 Intorlake: Chicago, 111. 2x75 1959 0.96 Jones + Laughlin: Aliquippa, Pa. 2x80 1957 1.00 3x190 1968 3.00 Cleveland, Ohio 2x205 1961 2.25 Kai a er: coco ©so\ Fontana, Calif. 3x120 1.50 2x220 2.30 McLouth: Trenton, Mich. 5x110 1958/69 2.8O Rational Steel: Great Lakes Div.: Ecorse, Mich. 2x285 1962 3.60 2x235 1970 2.00 Heirton Steel Div.: Weirton, W.Va. 2x360 1967 4.00 Granite City: Granite City, 111. 2x235 1967 2.20

i - 104 -

Table 1 : continued

No. of Conver- Annual capacity (mill, Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

USA, cont. Republic: Warren, Ohio 2x190 1965 2.50 Gadsden, Ala. 2x180 1965 1.50 Cleveland, Ohio 2x245 1966 2.8O Buffalo, N.Y. 2x130 1970 1.00 Sharon: Parrel1, Pa. 1x150 1974 1.00 US Staël: Duqucsne, Pa. 2x215 1963 2.60 Gary, Ind. 3x215 1965 4.4O South Chicago, 111. 3x200 1969 4.10 Lorain, Ohio 2x225 1971 2.8O Braddock, Pa. 2x230 1972 2.6O Wheeling-Pittsburgh: Mones3en, Pa. 2x200 1964 1.80 SteubenviUe, Ohio 2x285 1965 2.70 Wisconsin Steel: South Chicago, 111. 2x120 1964 1.20 Youngstown: East Chicago, Ind. 2x285 1970 3.00 SHORT TON TOTAL 89.36 5.6O EQUIVALENT METRIC TON TOTAL 81.O6 5.IO USSR Dnepropetrovsk, Ukraine 3x50 1967/68 O.8O Krivoi-Rog, Ukraine 3x100 1958 I.80 3x130 1965 Al 2.6O Yenakiyevo, Ukraine 3x130 1968/69 2.60 Iyioh: Zhdanov, Ukraine 3x100 1964/65 2.00 1x250 2.00 Azovstal: Zhdanov, Ukraine 2x350 3.5O Dzerzhinsk, Ukraine 2x450 4.00 Nakeyevakiy: Kirov (Central Russia) 2x270 3.00 Cherepovets ( " ) 2x400 4.OO Novolipetsk: Lipetsk, Cotral Russia 3x160 1966 3.5O 3x300 1974 A 8 3.00 3.00 Magnitogorsk, Urals 3x350 7.00 Novo-Tagil: Nizhniy-Tagil, Urals 3x100 1963/67 2.00 2x300 3.00 Chelyabinsk: Chelyabinsk, Urals 3x125 1969 2.20 West Siberian: Antonovskaya, W.Siberie 3x130 19469 2.20 3x300 1973,A7 3.00 3.00 2x270 2.70 - 105 - Table 1 : continued

No. of Conver- Annual capacity (mill. Company ters output m. tons raw steel) L/D plant per heat (tons Start up location raw steel) date Existing To be added

USSR, cont. Kuznetski: Novokuznetsk, W.Siberia 2x300 3.00 East Siberian: Svobodnij, E.Siberia 2x300 3.00 Karaganda, Kazakh 3x250 1970/72 4.5O 3x250 4.5O 3x300 5.OO Kazakhsk: Temir-Tau, Kazakh 2x350 3.5O TOTAL 40.20 44.20 VENEZUELA Zulia: Maracaibo 3x300 6.00 TOTAL 6.00 YUGOSLAVIA Skopje: Skopje 2x110 1967/- O.70 0.70 Zenica: Zenica 2x110 1976 1.10 Smederevo: Smederevo 3x100 I975/8O O.90 O.80 TOTAL 2.70 1.50

HORlLD TOTAL 366.459 148.38

Souroo : Metal Bulletin Monthly - August 1977 - 106 -

(vi) Bottom Blowing Oxygen Process ;

(a) OHM Procesa;

It had been felt that blowing pure oxygen through the converter bottom would have the inherent advantages of a quieter blow and better mixing. The OBM (Oxygen Bottom Maxhtttte) process was developed by Eisenwerk-Gesellschaft MaximilianshUtte mbH. in PRO, jointly with L'Aire Liquide of Montreal, Canada, and the first heat wa3 made in December 1967. By March 1968, regular production was started. The unique feature of the process is shielding of the oxygen tuyere by a largor diameter pipe throufh the annulas of which hydrocarbons, such a3 propane or natural gas, is blown. The endothermic decomposition of the hydrocarbon at the mouth of the tuyere effectively cool the tuyere. With this concentric tuyere, pure oxygen could be introduced into a steel bath without excessive refractory erosion.

The vessel for OBM process is similar to the Bessemer converter except for only six to fifteen tuyeres as against 25O to 300 in the Thomas converters. The inner oxygen tube is made of copper and the outer tube is of stainless steel. The converter shell is lined with dolomite bricks and the bottom is rammed with tar dolomite. Oxygen with lime powder is injected through the inner pipe and natural gas through the outer tube. The incoming of natural gas is about 9 kg per cm2, which is reduced to about 4 kg per cm2 and the flow rate is about 300 m3 per hour. The line pressure of oxygen is about 15 kg per cm2 which is re- duced to about 13 kg per cm2 in the converter. The oxygen flow rate can be varied from 4,000 to 10,000 m3 per hour. The ratio of oxygen to natural gas for ignition is approximately 9:1 and during tho blowing period this is reduced to 30:1. Natural gas consumption averages 6 m3 per ton of steel and oxygen consumption about 64 m3 per ton.

OBM vs. LP processes:

The advantage of the OBM process in comparison with the oxygen top-blowing processes are mainly as follows :

(i) Unlike the oxygen top-blowing process, only about a quarter of the iron is evaporated; consequently, less red fumes are developed. (ii) The iron oxide content of the slag which in contrast with other steelmaking methods, approaches equilibrium with the metal bath, is substantially lower. Due to (i) and (ii) above, the yield is increased by about 2.5 per cent compared with the oxygen top-blowing processes which means a decisive economic advantage of the OBM process. (iii) The intense agitation of the bath by the introduction of the refining gas through the bottom leads to a more rapid dissolution of the scrap, whereby the total refining time in the converter is reduced to 10 minutes.

J

^m - ÎOY -

(iv) The simultaneous introduction of lime powder and oxygen permits to obtain a completely slopping-free refining which is far-reaching and independent of the piß iron composition. Besides advantages relating to process control, also the design of the gas-cleaning equipment is affected thereby in a favourable way. (v) The amount of scrap to be processed by the OBM process is increased by aboui yj per cent compared with the oxygen top- blowing processes. The reasons are: the lower iron evaporation losses; the elimination of cooled lances; shorter refining time; and the possibility of pre-heating the converter during charging operation by introducing through tuyeres oxygen and natural gas in stoichiometric ratio. (vi) OBM plants require only two thirds of the building height than for oxygen top-blowing processes. Por this reason, OBM con- verters are particularly suitable to be installed in existing open-hearth steel plants. (vii) Due to the short blowing periods and the completely slopping-free blowing behaviour, a considerable increase in pro- duction can also be achieved in case of large OBM converters in comparison with LD converters.

(b) LWS Process;

A variation of OBM process is the LWS process (Creusot-Loire and Wendel-Si de lor with Sprunck and Co.). In r.'.-.'S process fuel oil is used for shielding the oxygen stream instead of natural gas. The first commercial operation started ir 197 ¡ in a 30-ton converter and the process, like OBM, is used for refining high-phosphorus iron. The use of oil in LWS process ensures better safety in operation compared to the use of propane or na- tural gas. The process is expected to be attractive in places where natural gas i s not available and propane is expensive.

(c) Q-BOP Process:

The OBM process was adopted by U.S. Steel to large furnaces and was termed as Q-BOP process. The letter «Q» stands for 'quiet, quick, quality« and emphasizes the advantages of the oxygen bottom-blowing process.

The metallurgical performance of the Q-BOP has proved to be ex- cellent. Phosphorus could be removed to low level. The ability to intro- duce powdered lime into the steel bath results in good desulphurization and steels with S content of 0.02 per cent are produced from hot metal containing 0.07 per cent sulphur. Nitrogen levels at turndown are generally below 0.00?5 per cent and hydrogen content as about 2.6 ppm.

The process developed for treating low phosphorus iron and for adoption on large converters for high tonnages has elaboratod -buyer*-- gas control system to ensure that the different gases are iupplied in the right quantity and sequence to the converter. The blowing i^»: for a 200-ton Q-BOP converter is about 12 mnutes, as against "> ¡imues fo- LD converter. -106 -

(d) SIP Process: The submerged injection process SIP is an offshoot of the OBM process and was developed by the Sydney Steel Corporation, Canada, on their 200-ton tilting open-hearth furnace. The tuyeres arc located below the bath on the back slope of the hearth. The refining time is reduced to some 12 minutes for an oxygen rate of about 900 m^ per minute. Advantages claimed for SIP are high production rates, 2 to 4 P«r cent increase in yield and less particle content in the waste gases due to quiet bath conditions. Since the endburners as in the conventional open-hearth are retained, the scrap melting ability of SIP is more than the other processes and there is no difficulty in melting upto 60 per cent scrap in the charge. Results of experimental1 heats in U.S. Steel's 30-ton Q-BOP converter indicate that rimmed and mechanically-capped low carbon steels of both hot and cold rolled quality; deep drawing tin- plate and other tin mill products including corrosion resietanoe types; structural quality plates including carbon-manganeBe steels and low alloy high strength steels, as well as high carbon rail steels are com- parable to similar products from conventional open-hearth furnace or LD converter. It has been estimated that the capital investment on bottom-blowing installation is expected to be lower than that on LD plants. A study re- cently completed by Dasturco, India, has shown tho revamping and aug- menting the capacity of a Thomas converter shop; in Egypt, could be achieved at half the oost for OBM converter as against with revamping with installation of LD converter. Similarly, the conversion of existing open-hearth shops by installation of bottom-blown converters is expneted to be more economical than LD. - Wj -

<- v0UrP!2tl^,,*hO ?apaCity of the °*•en bottom-blowing installations is about 18 million tons. The worldwide list of oxygen bottom-blowing converter installations is given in Table 2.

Table 2 • World Oxygen Bottom-Blown Pianti

Start Country and Company Location Process No. Conver- Capacity up ters Heat Crude Steel tons mill, tons

FRC Eisenwerk-Gesel Isohaft Salzbach- Maximilinnchuette GmbH. Rozenberg OBM 1967 35 1.10 Stahlwerke Roechling- Burbach GmbH. Voelklingen OBH 1969 45 0.55

France Società des Aciéries et Trafileries de Neuves-Maison Chat i Hon OBM 1969 35 0.60 Wendel-Sidelor Valenciennes OBM 1970 80 0.90 Hagondange LWS 1973 50 0.6o Rombas LWS 1971 35 0.30 Cockerill-Ougre- Province Rehon OBM 1973 25 0.40 Société des Hauts Fourneaux de las Chiers Longwy LWS 1973 25 0.40 Union Sidérurgique du Nord et L'est de la France (USINOR) Longwy OBM 1970 45 0.40

Belgium Cockeril1-Ougre- Province Marchienne OBM 1971 2 40 0.44 ForgeB de Thy-Marcinellc et Monceau Monceau OBM 1971 4 40 0.88

Lux mbourfl Miniere et Métallurgique de Rodange Rodange OBM 1970 30 0.66

South Africa South African Iron and Steel Industrial Corp. Ltd. Pretoria OBM 1971 40. 0.30

._.v> -lio -

Table 2 : oontinued

Country and Company Location Process Start No. Conver- Capacity up ters Heat Crude Ste tons mill.tons

United States U.S.Steel Corporation Soutn Works Chicago Q-BOP 1971 1 30 Fairfield Works Q-BOP 1974 2 200 3.50 Gary Works &-BOP 1973 3 200 5.00

Canada Sydney Steel Corp. Sydney SIP 1971 3 225 1.25

Sweden Surahammars Bruks AB Suraharañar OBM 1974 1 40 0.15

TOTAL 17.43

Souroe : SEAISI - Jan. 1976

Table 3 gives the trend of development of oxygen processes during the last deoade in the different regions of the world.

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It can be sonn that despite metallurgical advantages of Kaldo and Rotor processes there has been no development for these processes owing to their complexity. The Q-BOP process is becoming increasingly popular.

(2.3) Continuous Steelmaking Processes

Considerable experimental work has been carried out on the con- tinuous steelmaking processes. The following are the different pro- cesses which are under development stage :

IRSID process WORCRA process HEARTH process BTSRA process NRIM process

(i) IRSID process;

In this process the actual refining takes place in a reactor fed with regular and known flow of hot metal by means of oxygen supplied through a vortical lance, which also injects fluxes for slag formation. The metal-slag mixture flows into a second vessel where separation takeB place. Oxygen consumption is about 48 m3 per ton of steel and the yield of metal is around % per cent.

(ii) WORCRA process;

The process developed in Australia consists of continuous con- version of iron ore to steel by fast smelting of composite pellets in a low shaft furnace with sequential refining of the molten hot metal in a launder-like furnace. The iron yield is reported to be 99 per cent. Lime consumption is said to be 40 to 50 per cent less than that of LD eonverter and oxygen consumption is less by I5 to 20 per cent.

(iii) HEARTH process:

Steelmaking is carried out by this process developed in USSR in a system of open baths. The flow of metal from bath to bath occurs by gravity because of difference in levels and the oapacity of eaoh bath Ì8 35 kg. Each bath carries out some specific part of steel- making process. The furnace is fired with natural gas using pre-heated air for combustion. Oxygen (10 to 25 m3 per ton of iron) is injected into the bath means of lances. (iv) BISRA process; In the spray steelmaking process developed jointly by BISRA and Million Iron Works in U.K., a stream of molten pig iron is exposed to intimate oxidation reaction with oxygen jets. Slag formation is achieved by injecting powdered lime with oxygen. Oxygen consumption is reported to be about 55 ">^ per ton of steel. (v) NRIM process; The process, in experimental stage, consists of multi-stage trough-type furnaces and has been developed in Japan. - 113 -

(2.4) Electric Steelmaking Processes;

Electric current can be used for heating in two ways : (i) by utilizing the heat generated in electrical conductors by their in- herent resistance to the flow of current and (ii) by utilizing the heat radiated by tii electric arc.

(i) Resistance method - two general methods of heati ng by re- sictance are possible : (a) the indirect method in which the charge is heated by radiation and conduction from separate resis tors through which current is passed. This method, however, is impract icable for steelmakinfc; (b) the direct method in which the current i a passed through the metal charge or bath itself. A hi^h-volta^e 1 ow-amperage current is transformed to low-voltage high-amperape curre nl and passed through the bath or charge. The bath acts as a secondary circuit for the current which is generated from a primary circuit by induction. This method is therefore called induction heating.

(ii) Electric arc method - arc heating may be applied in two penerai ways : (a) the arcs may be made bet ween electrodes supports) above the metal in the furnace which thus is heated solely by radiation fron the arc. This is commonly known as indireot- arc heating; ani (b) the arc may be made between the electrodes and the metal. This method, known as direct- arc heating allows current to flow throjgh the bath, so that heat dcvel- oped by the electrical resistance o f the metal in added to that radiated from the arcs. This system usim; a non-conduction bottom, has been successful in stoelmaking in elect • ic furnaces.

There are three different types of furnaces used for steelmaking;

(i) the open-bath arc furnace which is comparable to an open- hearth furnace (ii) the electric shaft furnace which is the electrical version of the blast furnace (iii) the low-shaft or submerged arc furnace which lies between the first two.

(*) Open-bath furnaces: In open-bath furnaces, the electrode is in contact with the slag, but it is not immersed in the col id charge. The furnace operates as on isothermal zone where the reactions are limited to the direct reduction of the oxides, the eventual carburization of the liquid metal ara' the formation of slag.

A recent development of the furnace is the Lubatti furnace whose bath is not actually open but is father covered by a very small layer of charge material.

The Strategic-Udy process employs this type of furnace using pre- heated highly reduced material. A 33»0O0 kva industrial unit has been commissed in Venezuela sometime back.

Íii) Electric shaft furnace; A few furnaces of this type were 500 - 600 kw at Domnarvat, Sweden^, but tha performance, was not quite satisfactory in comparison to that of open-bath or the submerged

V* - 114 -

aro furnaces. The furnaoes did not become popular and were finally abandoned.

(iii) Submerged arc furnaces; One of the first furnace of the submerged arc type was made by Heroult. These designs were later in- dustrially developed by Tysland and Hole. Today, most of the electric ironmaking plants make use of the submerged arc furnace. Tysland-Hole furnaces of 50,000 kva capacity or more are operating in several parts of the world. A 60,000 kva furnace has been constructed and is oper- ating at Mo-i-Rana.

Prom the time of its invention, the electric furnace has been devoted to the making of special steels and has therefore been characterized by modest heat size and low hourly output. Its potential increased towards the 1960s, which led to the UHP (Ultra high power) concept. The main features of this technique are :

(a) an increase in transformer power, making possible the regular attainment of specific power levels of 500 to 6OO kva/ton. Ugine's 100-ton furnace at Fbs and the one of Sanyo Steel»s 80-ton furnace at Himeji have capacities of 77 M7A and 60 MVA respectively. (b) thermal efficiency is much improved using short, stable ores and high voltage and power, the power factor falling from 0.9 to O.71.

Furnaces in the 80-100 ton range are quite common in many countries. The U.K., U.S.S.R., U.S.A., Italy, South Africa, etc. have furnaces of 150-ton capacity or more. The North Western Steel and Wire Company has a furnace of 400-ton and another of 700-ton capacity. Auxiliary heating arrangements are made outside the furnace for reasons of economy in electric power and to enhanoe the productivity. (2«5) Atomic Energy and Steelmakirutt

The application of atonic energy to steel production would involve the use of a reactor to generate both electricity and the hot reduoing gas needed in the direct reduction process. Two methods have been con- sidered feasible :

(a) using the heat from a high-temperature gas-oooled reactor (HTOR), to reform hydro-carbon gas for the direot reduction of iron ore, the temperature being indirectly supplied by the hot helium from the reactor. The direct reduction sponge iron thus obtained would be refined to steel in an eleotric furnace powered by heat from the reactor.

(b) using reactor heat to obtain hydrogen (by splitting water) which is then used for the direct reduction of iron ore obviatin* the use of fossil fuel.

-. V' -115 -

The over-riding problem at present is to design a safe, long-life oatalystio reformer that can be heated by hot helium gas from the re- actor. West Germany, Japan, Switzerland, U.S.A. and the U.S.S.R. are aotive in developing this technology. U.K., Belgium, France and Italy have also joined together to develop nuclear steel-makins technology.

However, it is expected that first use of nuclear fission in steelmaking would not be there earlier than I985-90, and may be, even later by 5 to 10 years.

(2.6) Share of each Process in Steel Production;

Steelmaking has undergone a substantial transformation in the last two decades or so, owing to the introduction on an industrial scale of pure-oxygen melting processes, the development of electrie furnaces for the production of ingot steel and the introduction of metallurgical processing downstream of the steel production furnaoe.

This development is summarized in Table 4 and the forecast of the share of each process by the end of the century is given in Table 5.

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The output of steel of some of the oountries shows striking differences in the choice of technology. ThiB is due to the particular infrastructure facilities of the steel industry in these countries.

Table 6 shows country-wise share of different processes.

Table 6 : Country-wise share of Each Processes (in per cent)

Country Year Thomas Open Hearth Electric Oxygen Output in million tons Federal Republic of Germany 1960 43.8 47.3 6.4 2.5 34.032 1970 8.? 26.5 9-4 56.7 45.041 1975 1.4 16.9 11.2 7O.4 40.415 Austria 1960 — 31.3 12.6 56.1 3.163 1970 16.3 12.1 71.6 4.078 1975 7.4 11.8 8O.8 4.068 Belgium i960 91.1 5-8 3.1 6.698 1970 41.6 2.2 3.6 52.6 12.607 1975 1.4 5.8 92.8 11.584 Bulgaria I960 90.0 10.0 O.260 1970 26.1 20.1 53.8 1.800 1975 22.8 21.3 55.9 2.265 Canada 1960 89.2 10.8 5.164 1970 - 86.6 13.4 11.212 1975 23.6 18.6 57.8 13.025 Spain I960 13.8 71.4 14.8 I.938 1970 26.4 35-2 38.4 7.429 1975 9.8 36.1 54.1 11.242 United State3 of I960 1.2 87.O 8.5 America 3.3 9O.O67 1970 36.5 15.3 48.1 122.120 1975 19.O 19.4 61.6 IO8.25O Finland I960 39.9 60.1 O.278 1970 13.8 22.3 63.9 1.169 1975 8.7 17.0 74.2 I.618 France 1960 6O.9 29.9 8.7 0.5 17.181 1970 42.2 18.8 9.8 29.2 23-774 1975 15.5 7.2 12.8 64.5 21.530 Hungary I960 90.2 9.8 I.887 1970 90.7 9.3 3.110 1975 - 90.8 9.2 _ 3.671 - 119 -

Table 15 : continued

Country Output in Year Thomas Open Hearth Electric Oxygen million tons Italy 1960 5.5 55-9 38.6 8.461 1970 28.O 40.5 31.5 17.277 1975 11.3 43.0 45.7 21.836

Japan 1960 - 68.0 20.1 11.9 22.138 1970 4.1 16.8 79.1 93.322 1975 1.1 16.4 82.5 102.314 Luxembourg 1960 98.0 — 2.0 4.O84 1970 60.6 1.8 37-6 5-462 28.5 1975 1.4 70.1 4.624 Poland 1960 92.3 7.7 6.661 1970 81.2 4.8 14.0 11.750 1975 65.9 8.7 25.4 I5.OO7 Portugal 1960 — 24.7 75.3 0.968 1970 18.9 81.1 O.385 1975 22.0 78.0 O.43O Romania i960 89.I IO.9 1.671 1970 62.O 9.3 28.7 6.517 1975 49.9 12.7 37.4 9.549 United Kingdom i960 8.0 84.9 6.9 0.1 24.571 1970 48.3 20.0 31.7 28.316 1975 22.0 27.6 50.3 20.198 Sweden i960 14.O I 34.0 48.0 4.0 3.219 1970 3.8 24.4 39.5 32.3 5.497 1975 15.7 4O.9 43.4 5.611 Czechoslovakia 1960 3.9 83.8 12.3 6.768 1970 2.0 68.3 11.7 18.0 11.480 1.1 1975 64.2 IO.9 23.9 14.324 U.S.S.R. i960 2.7 88.4 4.5 4.4 56.627 1970 1.0 72.6 9-2 17.2 115.889 1975 O.7 64.7 10.0 24.6 141.325 Yugoslavia 1960 92.0 8.0 1.442 1970 - 73.9 19.3 6.9 2.228 1975 62.4 26.4 11.2 2.916

Souroe t U.K.E. and S.O. Steel/(3E.3/H.3/Add.1

à - 12C -

3. Factors affecting Process Selection;

Of the many different steel production processes employed in the past, only a few have survived in the face of stiff competition. Many decisions have to be made when formulating plans? for the estab- lishment of a new iron- and steelworks, or when considering a major expansion of an existing works. One of the most important of these is the process route by which the available raw materials are to bo con- verted into the required product mix.

If the general location of the steelworks is already decided upon, certain parameters will already be fixed, such as the IOOPI market demand and its pattern of .nrowth which in turn determines the size of works and its range of products, cost of the services avail- able, etc.

The choice of processes is influenced strongly by :

(i) The cost and availability of iron ore and steel scrap; (ii) The cost and availability of coking and steam coal, oil, natural gas, electricity, charcoal and other fuels; (iii) The cost and availability of capital for the purchase and construction of facilities; (iv) The availability of trained, operative and technical staff; (v) Transportation facilities available to move the large tonnages of raw materials involved; (vi) Environmental considerations, primarily the disposal of water and waste rock from mining, and slag from smelting and refining operations; (vii) The possible risk involved in choosing a particular technology which may be at various stages of development; (vili) The cost of capital available.

(3.1) Optimum Works Scale;

With the increasing size of most production units, the optimum size of an integrated steelworks has risen accordingly. There is no general law governing the economics of works size. Each individual case must be carefully examined to determine the optimum solution. To arrive at a suitable works scale, the most economical rolling mill capacities to match the current and forecast market demands, are first chosen. Then working backwards through the process stages, optimum capacities of all other production units ave determined. - 121 -

Table 7 lints the approximate ran/iO of economic viability for the capacities of some of thr- major units, illustrating the com- plexity of the balancing problem.

Table 7 : Approxim-.te Range of Economic Viability of some of the Major Units

Production Unit Capacity fiance - mil] ion tons/year

Blast I'Urnace 1.0 to 4.0 iron Sintor Plant up to 8.0 sinter Coke Ovens Battery up to 2.0 coke Lu St eelmaking Shop up to 10.0 raw steel Slab Mill 2.0 to 6.0 raw steel Bloom Hill 1.5 to 6.0 raw steel Continuous Slab Caster up to 2.0 raw steel Continuous Bloom Caster up to 1.0 raw steel Continuous Billet Caster up to 0.5 raw steel Plate Hill O.5 to 3.0 steel product Hot Strip Mill 1.0 to 6.0 steel product Cold Strip Mill 0.1 to 2.5 steel product Structural Mill O.3 to 1.5 steel product Bar Hill 0.01 to 1.0 steel product Rod Mill 0.1 to 1.0 steel product

Source : SEAISI Quarterly, Jan. 1977

(3.2) Cost Data! ,

._ Í1) Brides the technical advantages of OBM process over LD process mentioned earlier in this paper, Dasturco, Consultants, India, have estimated that the capital investment on bottom-blowing installation is expected to be lower than that on LD shop.

0 10 81, 8tudy made by the above • JÍV ! !!? consultants it has been indi- cated that the cost of modifying existing Thomas converters at the Helwan Steel Plant in Egypt to OBM would bo approximately at half the cost compared to that required for revamping with installation of LD converters. Similarly, the conversion of open-hearth shops by in- SS 1 n10? °î bottora-blown converters is likely to be more economical than LD plants.

The consultants have also estimated the following relative in- vestment costs for different stcelmaking processes inclusive of coat of oxygen plant, ingot casting facilities and calcining plant. These oost figures are given in Table 8. - 122 -

Table 8 : Relativo Investment Costs Basis: 1 million ingot tons per year

Process Investment per annual ingot Relative Investment ton US3 Index

Open Hearth 75 100 LD 47 63 0BM/r,WS(Q-BOP) 42 60 Electric Arc Furnace 56 75

Source i SEAISI Quarterly, Jan. 1976

(il) A study of estimated capital costs of some new steel producing facilities made by Paul Marshall in 1976 is summarized in Table 9.

Table 9 ; Estimated Capital Costs

Capacity in tons/year Cost in $/ton Total in Procens Sequence million Raw Finished Raw Finished dollars Steel Steel Steel Steel

(a) 35 t. EP, Cont. Caster, hot mill 50,000 47,000 240 255 12 (b) DR-35 t. EP, Cont. Caster, hot mill 50,000 47,000 340 361 (c) 70 t. EP, Cont. 17 Castor, hot mill 100,000 94,000 230 (d) 70 t. EP, Ingot Cast 245 23 ins, hot mill 100,000 85,000 210 247 21 (e) 2-150 t. EP, Cont. Cast, merchant mill 500,000 450,000 320 160 (f) DR,2-150 t.EP, Cont. 355 Cast.,merchant mill 500,000 450,000 426 (g) 2-150 t.EP,Ingot 475 213 Casting, primary and merchant mills 500,000 375,000 370 500 I85 (h) 1-150 tpd BP.Coke oven, 1-100 t BOP, Cont. Cast., merchant mill 500,000 450,000 610 670 (i) 3-200 t.CH,Cont.Cast 305 merchant mill 500,000 450,000 340 380 170 (j) 3-200 t.EP,Cont.Cast hot mill,merchant mill 1 ,000,000 900,000 346 385 346 (k) DR,3-200t,EP,Cont. Cast.,hot mill,heavy structural mill 1 ,000,000 900,000 606 670 606 - 123 -

Table 9 : continued

Capacity in tons/year Cost in S/tton Total in Process Sequence million Raw Finished Raw Finished dollars Steel Steel Steel Steel

(1) 3-200t.RF,In£Ot cast- ing,primary mill,hot mill,merchant mill 1,000,000 750,000 390 520 390 (m) 1-6000 tpd BP,Sinter piant,coke plant, 2-150t BOF pi ant, Cont. Cast.,hot mi 11,merchant mill 2,000,000 1,600,000 477 600 (n) DR, 6-200t, EP, Cont. Cast. 955 hot mill,cold mill, Ralvanizin/r 2,000,000 1,600,000 482 603 (o) Fully intonated plant, 965 BF.Coke piant,BOP,Cont. Cast.for merchant,bar and structural mills, Cont.hot mill, hot and cold sheet mills, coated products, plate mill 18,000,000 6,000,000 675-750 900-1,000 6,000 I Source : UNIDO/lCIS.25

v * The.í"V0 Ta^le Bhowa a "^ ranee of capital cost variations, namely between «210 and $750 per ton of raw steel at 1975 prices.

Table 10 /rives comparison between index of capital costs for BF-BOF and DR-EF installations for different plant capacities.

Table 10 : Index of Capital Costs BF-BOF and DR-EF plants

Index of Capital Cost Plant Capacity in million tons DR-EF

0.2 0.3 O.4 O.5 0.6 0.7 1.0 2.0 3.0 5.0

Source : UNIDO/lCIS.25 - 124 -

AB shown in Table 10, capital noni decreases by about 48 per cont and 37 per cont as plant capacities increase from n.p to 3.0 million tons for BF-BOF and DR-EP plants, respectively.

Tables 11 and 12 show capital cost;; for a 3 million tons BF-BOF plant and for 0.5 million tons DR-2F plant, respectively.

Table 11 : Capital Costs 3 million tons BF-BOF Pie nt

Millions Installed Steel- ! Capital Cost of making capacity Struct we dollars idoli ars/ion) (per cent)

Coke Plant 16R.0 Blaat Furnac- ??5.n Basin Oyyo'n ""urnare 130.0 Continuo'in C'i:;t'!rr; 131.0 Mixed Roll da- Facilities '.63.0 General Faci 1 i lien 1?r,.0

Sub-total, fired assetr, 1,3/|?.0 Engineering, procurement and inspection (*,

Sub-total, project imple- mentation and pre-operatine expenses

Fixed capital costs Infrastructural Investments

Sub-total, fixed capital crsts plus infrastructure

Working Capital (15# of fixed ass etc:) Interest paid during implementation

Grand Total

Source : UNIDO/lCIS.25 - 125 -

Table 12 : Capital Costs 0.5 million tons DR-EP Plant

Millions Installed Steel- Capital Cost of making capacity Structure dollars (dollars/ton) (per cent) D.R. (350,000 t) 38.4 77.0 25.5 Electric Furnace (500,000 t) 20.0 40.0 13.2 Six-Strand Caster (500,000 t) 22.5 45.O Merchant Bar Mill (450,000 t) 14.9 31.5 63.O 20.9 Sub-total,fixed assets 112.4 225.O 74.5 Engineering, procurement and inspection (5^ of fixed assets) 11.0 3.6 Administrative, advisory and expediting costs (3$ of fixed assets) 7.0 2.3 Pre-operating expenses (3$ of fixed assets) 7.0 2.3

Sub-tot al,project implementation 25.O 8.2 Fixed Capital Costs 25O.O 82.7 Infrastructural Investment (15$ of fixed assets) 34.0 11.3 Sub-total,fixed capital oosts plus infrastructure 284.O 94.0

Working Capital (8$ of fixed assets) 18.0 6.0 Total 302.0 100.0 Interest paid during implementation 10.0

Grand Total 312.0

Source : UNIDO/lCIS.25

The estimates given in Tables 11 and 12 do not take into aooount costs for mining, power, housing, contingencies and interest paid during construction period.

(iii) In a study conducted by the UNIDO, the operating cost for a 3-million tons BP-BOP installation, located in the U.S.A., Brasil, Western Europe and Japan, has been estimated at $134.70 per ton. - 126 -

The percentage distribution of the inputs in relation to the total operating oosts, is shown in Table 13.

Table 13 : Cost Structure - BF-BOF (in per oent)

Blast Furnace Shop Basio Oxygen Steel- making Raw Materials and Primary Energy 84.7 93.0* Utilities 1.9 LO Laboor 5.2 0.8 Overhead 3,3 0.5 Maintenance (4Í? of investment) 2.0 2.9 Local taxes and insurance 0.1 0.4 Depreciation (5.5$ of investment) 2.8 1.4

Total Costs 100.0 100.0 # Liquid metal from the previous process and transfer costs.

Source : UNIDO/lCIS.25

J -127 -

(iv) The capital investment and operating coat for a I.71 million tons per year new eleotric furnace are given in Table 14. Cost figures for a (similar capacity new oxygen furnace are given in Table I5.

Table 14 : Cost Structure in New Electric Furnace Shop

Annual Design Capacity: I.71 % 106 tons Capital Investment: $65 million Location: Great Lakes

Units Used in Units Con- Costing or sumed ner ton Annual Cost of Product $/Pon of Basis $/Wt Product Variable Costs Raw Materials reduced pellets ton Fe 102.88 scrap 0.75 77.16 ton 80 0.32 25.6O Energy Electric Power Purchased kWh 0.016 600 Electrodes 9.6O lb O.55 10 5.5O Hater Process (Consumption) Cooling (Circulating Rate) Direct Operating Labor (Wages) man-hr 7.00 0.3 2.10 Direct Supervisory Wages 15# Labor 0.32 Maintenance Labor and Materials 6* CI 2.27 Labor Overhead 35* (L+S) O.85 Misc.Variable Costs/Credits Refractories 2.00 Fluxes, Oxygen, misc. nonmetallies 1.00 Metallic Additions I.50 TOTAL VARIABLE COSTS 127.90 Fixed Costs Plant Overhead 65* (LfS) I.57 Local Taxes and Insurance 256 CI O.76 Depreciation 18 years 2.10 TOTAL PRODUCTION COSTS 131.83 Return on Investment (pretax) 20* CI 7.56 TOTAL 139.89 Source : EPA-6ooA-76-034c-Industrial Environmental Research Laboratory, USA. - 128 -

Table 15 : Cost Structure in New Basic Oxygen ProoesB Annual Design Capacity: 1.71 million tons steel Capital Investment: $45 million Location: Great Lakes

Units Usod in Units Con- Costing or sumed per Annual Co3t ton of ft/Ton of Basis SAJnit Product Product VariaMe Costs Raw Materials Hot Metal ($yf Fe) 3 ton IO6.42 O.83 BO. 33 Scrap ton 80.00 0.35 28 Energy Electric Power Purchased kWh 0.016 30 O.48 Energy Credits (Specify term) 6 Carbon monoxide 10 Btu 2.00 0.44 (.88) Water Cooling (Circulating rate) 1000 gal O.O5 2 0.10 Direct Operating Labor (Wages ) man-hr 7 O.25 1.75 Direct Supervisory Wages I55S labor O.26 Maintenance Labor and Materia Is % CI 2.09 Labor Overhead 35/0 (LfS) O.7O Misc.Variable Costs/Credits Oxygen ton 10 0.08 O.8O FeMn, Lime, Spar 3.00 Slag Disposal, Hot Metal, Scrap Treatment 1.00 TOTAL VARIABLE COSTS 125.63 Fixed Costs Plant Overhead 6556 (L+S) 1.3! Local Taxes and Insurance 2$ CI O.52 Depreciation 18 years 1.45 TOTAL PRODUCTION COSTS 128.90 Return on Investment (pretax) 2095 CI 5.23

TOTAL 134.14

Source : EPA-6O0/7-76-O34c-Industrial Environmental Research Laboratory, USA.

-j - 12'; -

(v) Capital cost per ton of stoel marie by the basic oxygen prooens for different Rapacity plants in shown diagramatically in Fi#. 1.

Fitf« 1. Capital cost per ton - capacity of baaic oxypen furnace 70 -: V.100 enxdt w sight - tono 60 *è 5o\ 50 VHoo- Source : Stahl und Hisen, 90 (1970), No. 4. 40 2 converters *-•»**-.» ' 200 '3 convertira I 30 -I—J •—•«?50 Smeli cycle: 35 min. 20 Operation: 84OO h/yoar ProductH : Slabs | 10 I

0 * 2 , 3 4 5 6 7 8 Production capacity in nill.t/ynav

(vi) A recent study made by Jack R. Miller, Iron and Stoel Industrien Consultant, USA, has shown that for a one million tona per year pia. t for producing low-carbon billets, (a) the estimated capital costs of a DR- P combination plant were 3? per cent lower than an eauivalent BF-BOP com- bination, but ?8 per cent higher than a stoel-scrap-electric furnace J!5ZEF1 iniätallati°n; and (b) production conts were lowest and profitability hißhest for the DR-EF operation. The profitability in this case was 14 oer cent compared with 7-5 per cent for the BF-BOF and 8.4 per cent for the' SS-EF processor.

Each of the above process combinations is ßtrongly sensitive to ohanses ln the availability and price levels of the main raw materials they consume. For the BF-BOF process, the dependency is primarily on coking coal or coke; for the DÎÎ-3F process, the reductant fuel; and for theSS-EF process, the scrap. The effect of fuel cost changes on profitability is more critical in the BF-BOF process than in the DR-EF combination.

The consultant considers DR-EF route *o be either equal to or better than the other two combinations with respect to product quality, environ- mental pollution control and flexibility in the choice of riant site locations. -130 -

4. World steel production during 1975 and 1976, along with different country's porcentaje contribution to world production are given in Table 17.

Table 17 : World Raw Steel Production

"T Production x 000 tons ; Output per capita kg i> World Country Output 1975 1976* 1975 1976* 1976 Europe West Germany 40,415 42,415 654 688 6.23 Belgium 11,584 12,146 1,183 1,238 I.78 Prance 21,530 23,226 407 436 Italy 3.41 21,836 23,416 341 415 3.44 Luxembourg 4,624 4,566 18,163 12,341 O.67 Netherlands 4,826 5,185 354 377 O.76 Denmark 559 723 110 142 0.11 U.K. 20,198 22,268 361 398 3.27 Irish Republic 81 58 26 18 0.01 Finland 1,618 1,646 344 Greece 345 0.24 700 700 77 77 0.10 Norway 919 894 230 222 0.13 Austria 4,068 4,478 541 598 0.66 Portugal 430 428 49 48 0.06 Sweden 5,611 5,213 684 632 0.76 S wit zeri and 420 520 66 82 O.O8 Spain 11,242 11,058 313 310 1.62 Turkey 1,464 1,770 38 44 0.26 W. Rurope 152,125 160,710 398 418 23-59 East Germany 6,480 6,650 385 396 O.98 Bulgaria 2,265 2,450 260 280 O.36 Yugoslavia 2,916 2,712 134 126 O.40 Poland 15,007 15,450 438 45O Rumania 2.27 9,549 10,500 451 492 1.54 Czechoslovakia 14,324 14,550 970 981 Hungary 2.14 3,671 3,650 348 344 O.54 Europe 206,337 216,672 402 420 31.80 U.S.S.R. 141,325 144,900 555 565 21,27 Ani a

Bangladesh 100 100 1 1 0.01 Burma 40 40 1 1 0.01 Taiwan 847 1,000 63 61 0.15 China 25,000 26,000 30 31 3.82 Hongkong 70 80 16 18 0.01 India 7,989 9,313 13 15 1.37 Indonesia 100 100 1 1 0.01 Iran 551 550 18 16. O.O8

J - 131 -

imK&ooxGAL morxix OK

oisrxMO WCLLMW OOVf XMM03 GAOTUQ

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t. Ifttroduotion 135 2. ttaal oMtiag 134 3* Xfcgot oaatiaf 136 4« Bottoa praaaura oaatiaf 117 5« CoatlBuoua oaatiaf 1 18 5«1 Growth paitara of oontinuoua oaatiaf 1 U 5*2 Coatlauoua oaatiaf installation« 143 5» 3 Cholea of prooaaa 1)7 3«4 Coat Data 201

W- — - 133 -

1* Introduction A brief aocount of different prooeaiee for eteel oast inga, inoludinf eontinuous caating, has been given in tha following pagaa. Information about tha various continuous oaating machina« inatalled in tha different countriea, ha« alao baan included. Tha oritarial for aalaotion of a pro- oesi including coat data, have alao baan mentioned. - 134 -

2. Stael Casting

As regards mechanical properties are conoerned, steel castings are inferior to wrought-steel products. However, steel castings cover a very large field and include steelmill service items like charging boxes, blast furnace bells, cinder pots, rolls for certain type of rolling mills, etc., transport industry items such as casting for couplings, journal boxes, brake-shoes, cylinders, valves, engine beds, etc., and several hundred other items of use in chemical, petroleum, mining, agricultural and con- struction industries, etc.

There are two classes of castings, static castings, and centrifugal caating8. The static castings are made by using proper type of moulds and make use of atmospheric pressure and gravity to form castings when molten steel is poured into the moulds. The centrifugal castings make use of centrifugal action to perform the function of gravity in static casting for flow of liquid metal. By the horizontal centrifugal casting techniques where the mould rotates on a horizontal axis, tubes, pipes, bushings, sleeves, etc. are manufactured. Gears, piston rings, impellars, propellers, turbine diaphragms, etc. are produced by the vertical centri- fugal casting method. Centrifugal castings are more sound and have fewer inclusions than those of static castings. The yield is also higher in the former case.

The mechanical properties of oast steels can be developed by suitable heat-treatment and addition of alloying elements. Nickel, chromium, manga- nese, molybdenum, and vanadium are the alloying elements comnonly used for improving the properties of the castings.

The ooomon heat-treatment applied to steel castings are:

A—»HM - Thi* treatment relieves the tensile and yield strength and - 135 -

increases ductility. Maohinability is also iaproved.

normalising - The treatment is similar to the annealing process. Bardar steel with higher yield and tensile strength is obtained. Internal •tresses are removed by tempering the normalised steel. benching end Tempering - These treatments are confined principally to high-carbon and alloy-steel oastings where high strength and resistance to impaot and/or abrasion is required. The steel is, first annealed or normalised, reheated and quenched. Tempering treatment follow« immediately. FI—e hardening - If the casting is required to have different hardness in two different sones of the oasting, such as a pinion gear whioh should have wear-resistant teeth with a maohinable bore, flame hardening technique is adopted. The casting is first annealed or quenched and then only the surfaoes to be hardened are heated to the hardening temperature by a toroh or induct ion-heating apparatus. The heated parts are then quenohed in water.

^ - 13í. -

3. Ingot Casting:

After a heat of steel is properly refined, the liquid steel is tapped into a refractory lined open-top steel laddie. Additions of alloying •ateríais and deoxidizers are made during tapping of a heat. The molten steel is poured or teemed into a series of moulds of the desired shape and dimensions, and after solidification, the ingot is stripped off the mould. Ingot moulds are of two principal types: (a) Big-end down; and (b) Big-end up.

The "big-end down moulds are further classified as (1a) open-top; and (2a) bottle-top. The big-end up moulds are also similarly classified as (lb) open-bottom; (2b) closed-bottom; and (3b) plug-bottom. The moulds are made of cast iron, the inner walls of which may be plain sided, corrugated, or fluted.

The rate of solidification of molten steel in the mould depends on thick- ness, shape and temperature of the mould; the amount of super-heat of the liqui steel; the type of steel and its chemical composition, etc Presence of pipe and blowholes, segregation, internal fissures, cracks and non-metallic in- clusions, etc. are some of the factors which are controlled by appropriate at«pa.

The ingot steel after reheating in soaking pita, is rolled into bloom, •lab or billet. These rolled primary products are then further rolled in the desired shapes and cross-section. - 137 -

4« Boti on Pressure Casting

A process to by-pass the ingot and primary mill stases in the pro-

duction of wrought steels, is the bottom pressure cf ating method. A

laddie filled with mother steel is placed in a presaure vessel. This

vessel is covered with a lid in which a pouring tube is inserted that

dips down into the mother steel almost to the bottom of the laddie. A

gooseneck connects the pouring tube to the mould in the casting position.

When air-pressure is applied to the pressure vessel, molten steel rises in

the pouring tube and gooseneck and enter the mould. The rate of casting is

controlled by regulating the pressure of air.

The mould is enclosed in a fiaste which has a gate that retains the mol- ten metal in the mould after the cast is completed. The gate is closed after the mould has been filled and the pressure vessel is then exhausted to the atmosphere. After the casting has solidified the mould is removed by »trip- ping machine. Where the drag and the casting are separated from the cope.

The casting is then separated from the cope by special maohines and placed on the cooling oonveyor. -138 -

5» Continuous Casting

Until reoently, steal in the form of blooms, slabs, and billets, was produced mainly by hot rolling of ingots to produce blooms and slabs. Billets resulted from the further hot rolling of blooms. However, some blooms and slabs are still produced by other means of hot working, such as forging by hammering or pressing.

Researches and development in many countries, resulted in industri- alisation of the method of continuous casting of molten steel directly into the form of slabs and billets, by-passing the ingot stage and the necessity for hot rolling operations.

The attractiveness of casting molten steel continuously into useful shapes, led to a long series of attempts to develop various designs of amohines. The problems posed due to high melting point, high specific heat and low thermal conductivity of steel, were gradually overoome. When molten steel comes into contact with the walls of the water- cooled mould, a thin solid skin forms. Due to thermal contraction, the skin separates from the mould shortly after solidifioation. The rate of heat abstraction from the oast inj being slow, molten steel persists with- in the interior of the seotion for some distance below the bottom of the mould. The thiokness of the skin inoreases due to the action of water sprays as the casting moves downward and, eventually the entire is solid. The mass of solid stesi oasting is supported as it desoends by driven pinoh rolls that also oontrol lino speed by controlling the rate of withdrawal of the oasting fro« the mould. Oscillation of the mould up and down for pre-deterained distane« at controlled rates during oast- ing éliminât« tendency of sticking of the oasting in the mould.

J - UJ -

The successful application of the continuous casting process in a steel plant is dependent upon many factors other than just mechanical équipaient and the feasibility. Some of the important factors which would determine the number of casting strands or laddie position, aret (i) tons of liquid steel per heat; or in other words, sise of the furnace (ii) tap to tap time of the furnace (ill) possibility to programme the tapping time (iv) total tons of steel to be cast per day (v) shape of cast product (vi) casting rate. The tapping temperature of steel is generally between 1650°C and 1690°C for concast operation depending in ,'ue life of the furnace re- fractory and tap hole condition. This is about 3O°-40°C hotter as com- pared to steel tapped for small ingot-making. The desired physico-chemical properties of billets produced by the conventional method is attained by close control of the process beginning from the ingot making stage, soaking and rolling. During the soaking and rolling stages, homogenity of oast structures are obtained by diffusion processes. On the other hand, the physico-chemical properties of billets produced by the continuous oasting process exhibit properties on the as oast condition. For obtaining properties of finished products using con- tinuous oast billets comparable to those products using conventionally produced billets, the following factors must be carefully examined as necessary tools in accomplishing the above mentioned objectives: (a) Surface configuration which include among >*n< , deformation and bending - 1... -

(b) Surface defects such as pinholes and oscillation marks (o) Scum

(d) Cracks - internal, longitudinal and transverse (e) Segregation of components (f) Kinds and distribution of non-metallic inclusions (g) Reduction of cross-sectional area (h) Grain size (i) Fatigne

The following are the principal types of continuous casting machines

in commercial use:

(i) Vertical typet The casting is supported in a vertical position

and the continuous length of casting is parted by gas cutting in the verti-

cal position. The cut-off piece is received by a tilting basket mechanism

that lowers it to a horizontal position. Since the machine height is 17 m

or more, this type of continuous caster require a tall building or deep

pit.

(ii) Curved type: In this machine, the solidified product after

cooling by water spray is bent by a aeries of rollers, from vertical to

horizontal position. Cutting off is accomplished on the horizontal cast-

ing. The machine height is thus reduced to about 10 m and consequently

the building height.

(iii) Bow type: Curved mould is employed in this type of machine, whioh is in oscillation. The cooling chamber is also curved. The height

of this machine, is therefore, reduced to one-third or less than that of

the vertical type of machine.

Pre-heated and insulated laddies and tundish are used. The latter

•ay have one or more nozsles that feed the metal to the mould whioh is made of oopper and is cooled by copious amounts of water. - 141 -

5«1 Growth pattern of Continuous Casting

The growth of continuous casting has been phenominal during the last two decades. Vertical machines requiring buildings of great height,

»re now coupled with bending and straightening devices and curved-mold assembly. The speed of withdrawal has risen to 1.5 - 2.0 m per minute for slabbing machines and from 2 to 4 per minute for square sections.

Thus hourly outputs per strand are 200 tph for flats and 15-36 tph for square sections, uninterrupted series of more than 200 heats have been possible with the usage of improved distributor refractories, rapid changeover systems for closing mechanisms and proper synchronization of processing furnaces and casting machines.

Table 1 shows the trend in the growth of continuous casting.

Table 1» Growth of Continuous Casting

World Steel World Casting Annual Growth Percentage Share Year production Capacity of Continuous in in in per cent Casting in Steel million tons million tons Production

1955 266 0.38 0.1 1960 325 1.65 34 42 0.5 1970 599 57.40 9.6 646 20 1975 140.00 21.5

Souroe: BCE - Steel Committee/CFB 3/R.3

It is •stimateci that by 198O nearly one third of all the steel production in the world, will go through the continuous casting route. Orar 50 per cent of the machines now in use produce billets, about

20 par oent are for blooms and the rest make slabs.

Continuous easting accounted for 30 per oent of the steel output in

Japan in 1975, and 20 per cent in Italy, Spain, and the P.R.O., I5 per oent in Pranoe and less than 10 per cent in the USA and USSR. There were 65I countries in 1976. It has been estimated that by the end of _J -142 -

1977t thtra «ill *• 734 aills in 66 oountriss. Tns utilisation rat« (output/production oapaeity ratio) on global basis, has risen fro» 38.5 psr osnt in 1970 to 64 psr o«nt in I974. - 143 -

5»2 Continuous Casting Installât ion« i

There are nor« than twenty manufacturing firms, marketing con- tinuous castina; machines of basically one of the three major types but incoporating speoial design features of their own. More than half the number of machines in operation, are of Concast make, followed by Demag, Danieli, Mitsubishi/Olsson, VBest-Alpine, Koppers, etc Table 2 lists the continuous oasting smohines in the world in- dicating number of strands, oasting dimensions, oapaoity, maker*s name, produots made, eto.

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Por the production of seamless pipes, world's largest centrifugal continuous caster, has been installed at the Keihin works of NKK in Japan.

Billets of 120 to 240 mm diameter are produced in a four strand caster and the monthly production capacixy is 27fOOO tons. Other relevant parti- culars of the continuous caster, are as follows:

Caster height - Overall height 34.8 m

Tundish Capacity 12 tons

Mould Cu - Cy alloy mould;

455 on long;

Cooling 110 t/hr/strand;

Lubrication, rape seed oil;

Rotation, 120 rpm max;

Oscillation, I40 cpm max;

Stroke, 26 mm max;

Withdrawal — 3.5 m per minute, max;

Metallurgical height — 16.5 m.

The yield of sound billets is 89 per cent and the length of billet is kept within - O.5 per oent. - 1*7 -

5»3 Choice of Process:

There are a number of technical and economic factors which influ- ence the decision to choose one of the three processes of casting, namely,

(i) Conventional small ingot casting practice

(ii) Conventional large ingot casting practice

(iii) Continuous casting.

The parameters influencing the choice of the process «re:

(a) production scale

(b) type and quality of product

(c) materials yield and balance

(d) investment and energy requirements

(e) operating costs

(f) manning

(g) technical requirements in supporting sectors

(h) management and control requirements

The conventional ingot casting/primary mill route involves con- siderable cost sources. With continuous casting the two independent functions, namely, casting and primary rolling, are combined into one simple process. The operation involved in the two processes, ars re- presented in Table 3. - l'iti -

Table 3î Steps in two processes

Ingot Casting/Primary Mill Continuous Casting

1. Furnace tapping 1. Furnace tapping

2. Laddie transfer to casting pit 2. Laddie transfer to casting

3. Casting into moulds platform

4. Transfer of the ingot moulds to 3. Continuous casting

the stripper yard 4. Subdividing of the cast strands

5. Stripper 5. Transfer of the cast material 6. Transfer of the ingots to the pit to the rolling mill

or pusher furnaces 7. Ingots placed into pit or pusher furnace

8. Heating the ingots 9. Transfer of the ingots to the primary mill

10. Primary rolling

11. Grinding of the rolled products

12. Transfer to the rolling mill

The applicability of the three processes to different types of ste«l products, is shown in Table 4« - îy, -

Table 4: Applicability of the three processes to different type3 of steol product

Small Ingot Large Incot Continuous direct rolling blooming Casting and breakdown

Reinforcing bar yes (1) yes (1) yes (1)

General Structural bar and section yes (1) yes (1) yes (1)

Low-carbon wire rod yes (2) yes (1) yes (1)

High-carbon wire rod yes (2) yes (1) yes (1)

Cold-drawing quality Doubtful yes (3) yes (4)

Cold-heading quality Impossible yes (5) yes (4,5)

Mechanical Structural carbon steel Difficult yes (5) yes (4,5) Low-alloy steel Impossible yes (5) Doubtful

High-alloy and Stainless steel Impossible yen (3) Doubtful

Source: S.Kojima - 3^ Interregional Symposium on I. and S. Industry, Brazil

Notes: (1) Easily applicable

(2) Only applicable for low quality level

(3) Surface conditioning required

(4) Over I50 mm square bloom recommended; surface

conditioning required

(5) Surface conditioning and guaranteed internal

quality required.

The energy requirements for blooming mill and continuous casting are

35-55 Kwh/ton and 10-30 Kwh/ton, respectively. Water requirement is more for continuous casting installation, namely 12-18 nr per ton per hour as against 4-7 m per ton per hour for blooming mill. •2CC

However, continuous casting can not be applied universally for the entire range of a flat-product mix. Por all outputs, there are often local factors to be examined in making the choice. The most critical considerations are those of scale and volume, yield and capital cost and, the steel quality. Continuous casting does not produce a satis- factory rimmed steel slab or bloom. - 201 -

5»4 Cost Data Investment costs depend very largely on geographical conditions, layout of the plant, product range, tariffs, economic policies of the country, local market costs, freight, labour costs, etc. These factors vary greatly from country to country.

The email ingot process is labour-intensive, requiring more employees per ton of production and increasing markedly as the output rises. The large ingot blooming process isa large-scale one, and so an increase in capacity utilization can effectively increase the productivity per employee. The continuous casting of square section products has a production limit per machine of 5OO - 600,000 tons.

(i) A comparative idea of operating costs for the three processes is given in table 5. However, it may be mentioned that the figures should be taken as indicative only. The current actual cost per ton would be more due to escalation and inflation. Since there will be variations in the local prices for copper moulds for continuous casting and for blooming mill rolls, comparison of operating costs, becomes only an approximation.

Table 5: Relative operating costs for the three process.

1 1 Process Items Consumption Cost, US$ per ton Steal 1 Ingot Bricks and refractories 7.0 - 10.1 Kg/t MouMs and plates 8.9 - 15.3 Kg/t 4.2 - 5.8 Large Ingot Bricks and refractories 7.2 - I5.O Kg/t Blooming Moulds and plates 8.4 - 16.6 Kg/t Heavy fuel oil 20 - 40 l/t Rolls O.4 - 0.7 Kg/t Eleotric power 35 - 55 kwh/t 6.6 - 10.4 Continuous Bricks and refractories 5.O - 18.0 Kg/t Casting Moulds 70 - 5OO heats/moulds 3.0 - 4.8

Source: S. Kojima - 3rd Inter-regional Symposium on I and 3 Industry, Brasil. - 202 -

The above figures show that the operating costs of continuous casting, are the lowest, the small ingot process comes next, and the

large ingot blooming process is comparât i ve lyv most expensive.

(ii) Arthur D. Little Inc. have estimated capital investment for continuous casting plant to be about US$300,000 for a 300 tons per day plant and about US$4,000,000 for a 4000 tons per day continuous caster.

(iii) H. Pastert and R. Oautschi (3rd Interregional Symposium on Iron and Steel Industry, Brazil, 1973) estimate investment cost per ton of installed capacity for a slab casting machine of 6000 casts per annum, to be 30 per cent lower than for the conventional process.

(iv) R. Missbach and J. th. Wasmuht (iD/wa.146/68) in a study have worke\ out comparative capital cost figures for continuous casting projects and the conventional process for different capacities. The information is summarized in Table 6.

Table 6: Comparative Capital Costs

Plant capacity, cost Conventional pouring Continuous casting and yield factor route route 0.8 million tons per year Capital cost, per cent 100 45 -55 Yield factor, per cent 83 approx. 97 approx. 1.2 million tons per year Capital cost, per cent 100 65 - 75 Yield ratio, per cent 87 approx. 96 approx. 1.5 million tons per year Capital cost, per cent 100 80 -90 Yield ratio, per cent 85 approx (killed 95 approx. steel)

(v) In a survey made by the Organisation for Economic Co-operation and Development on Continuous Casting of Steel in the USSR, it has been stated that the cost of converting liquid steel into cast slabs, is about 25 per cent less than converting it into rolled slabs and the casting process costs could be reduced further if the productivity of the machine could be increased by introducing new steelraaking equipment. At preeent for the plant at NOVO Lipetsk, two electric furnaces with 25 MVA transformers produce steel which i a continuously cast in two - 203 -

twin-strand machines. The steels generally cast are transformer and dynamo steels, rimming carbon steels, killed carbon and semi - killed carbon steels in various slab sizes which overall range from 24 jf K 6*>p to 40f X 6 ^ inches in section. Typical casting speeds quoted are in the range 32 - 36 in/min for the large slabs.

The two machines, when operating with 90 - 95 ton capacity laddies, have produced up to 800 tons in 8 - 9 casts/day.

The consumption of liquid metal/ton of slabs of transformer steel has been found to be respectively 26.3 and 24.3 per cent lower than at Kuznetsk and at Dneprospetsstal and Zaporozhstal taken together. The process corrts in the arc furnace shops, on the roughing mill3, and the expenditure on deoxidizers and addition materials at kuznetnk amount to 21.0, 5.9 and 2.2 roubles/ton in total. At Dneprospetsstal and Zaporozhstal, these amount to 24.4f 6.8, 2.3, giving a total of 34»0 roubles/ton. Hence, the saving for continuously casting the slabs is estimated at 7.7 and 8.3 roubles/ton respec+ively. The difference in costs for continuously casting the metal, ulus scarfing the cast slabs as against casting ingot, ar<1 ro'iui;: on a slabbing mill is given at an average of 0.8 rouble J/„on of cant slabs so that the real saving in these comparisons is placed at 8.5 and 9.I roubles/ton. This saving in coti, is expected, however, to increase still further with increase in the production of cast slabs.

The economic advantage of changing over to continuous casting, whilst largely due to the increased yield of sound metal or reduction in metal waste, also includes a reduction in the uxtra capacity of srteelmaking units and roughing mills which would otherwise be required to meet the planned rates of expansion. There would, therefore, be corresponding savings on these operations as well as reduced consumptions of de-oxidisers and flux materials on the liquid metal that is saved.