DOCSLIB.ORG

Experimental Investigation on Direct Reduction Followed by Magnetic Separation for Nb2o5-Bearing Ore

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Experimental Investigation on Direct Reduction Followed by Magnetic Separation for Nb2o5-Bearing Ore ISIJ International, Vol. 53 (2013), No. 8, pp. 1358–1364 Experimental Investigation on Direct Reduction Followed by Magnetic Separation for Nb2O5-Bearing Ore Xin JIANG,1)* Fengman SHEN,1) Ligang LIU,1) Xiaogang LI2) and Lin WANG3) 1) School of Materials and Metallurgy, Northeastern University, Shenyang, Liaoning, 110004 China. 2) Baotou Steel Group Mining Research Institute (Limited Liability Company), Baotou, Inner Mongolia, 014010 China. 3) Department of Mechanical Engineering, Shenyang Institute of Engineering, Shenyang, Liaoning, 110136 China. (Received on February 21, 2013; accepted on May 18, 2013) Recently a special attention is being paid on the ferroniobium production worldwide, especially in China. In present work, direct reduction followed by magnetic separation for Nb2O5-bearing ore is investigated. Reflected light microscope, scanning electron microscope with EDX, and high performance X-ray diffrac- tion were used for fundamental analysis. The experimental results show that, (1) the optimum reduction parameters are 0.9 of C/O, 1 200°C and 20 min. At these optimum parameters, the degree of metallization of ore-coal composite pellet is more than 90%. (2) In direct reduced pellets, metallic iron and slag have gathered respectively, and they can be magnetically separated. Nb and Ti are associated together and inserted in slag, and stay in slag phase after magnetic separation. (3) Based on the process of direct reduction followed by magnetic separation, 7.71% of Nb2O5-enriched slag is obtained, which is a good feed for producing ferroniobium or metallic niobium in electric furnace. The Nb2O5 content in Nb2O5- enriched slag is 1.8 times of the original ore, and the recovery of Nb is about 85%. These experimental results can give some theoretical references for industrial application in future. KEY WORDS: Nb2O5-bearing ore; ore-coal composite pellet; direct reduction; magnetic separation; degree of metallization. 1. Introduction 25000 Niobium is an important element for MRI (Magnetic 20000 Resonance Imaging) machines, high technology, and the steel industrial. Over three-quarters of the world’s niobium 15000 production currently comes from Brazil, with most of remainder coming from eastern Canada. Recently a special 10000 attention is being paid on the ferroniobium production 1–6) worldwide, especially in China. China has been a top Imports, Metric tons 5000 importer of ferroniobium in recent years, and its imports have increased over the last decade (Fig. 1). 0 In tradional process of ferroniobium production in China 2000 2002 2004 2006 2008 2010 2012 include, (1) the raw mineral is processed primarily by phys- Year ical processing technology to get Nb2O5-bearing concen- Fig. 1. Chinese imports for niobium. trate. (2) The Nb2O5-bearing concentrate is used to produce sinter or pellet. (3) Sinter or pellet is feed into blast furnace (BF) to produce Nb-bearing liquid iron. (4) Nb is oxidized tant factor for producing ferroniobium or metallic niobium. to niobium oxides in converting process (BOF), and Compared with Sinter-BF-BOF route, reduction followed enriched in slag. In this long Sinter-BF-BOF route, particu- by magnetic separation route has the following advantag- larly in BF, some Nb presents in liquid iron, and some Nb es.8–11) (1) At the condition of BF, the reducing potential and oxides present in slag because the selective reduction of fer- reducing temperature are uncontrollable, and they are strong rous oxides and niobium oxides can not be achieved in BF. enough to reduce both ferrous oxides and niobium oxides. So the recovery of Nb is very low (about 72%) and the ener- At direct reduction process, ferrous oxides can be reduced, gy consumption per unit Nb produced is very high.7) but niobium oxides can not be reduced by controlling reduc- As we all know, the grade of Nb2O5 content is an impor- ing potential and reducing temperature. So, direct reduction is an effective process to achieve selective reduction. (2) In * Corresponding author: E-mail: [email protected] BF and BOF, the Nb2O5-enriched slag is liquid. But in mag- DOI: http://dx.doi.org/10.2355/isijinternational.53.1358 netic separation, the Nb2O5-enriched slag is solid, so the © 2013 ISIJ 1358 ISIJ International, Vol. 53 (2013), No. 8 energy consumption is relatively lower. Therefore, aimed –74 μm is about 76%, and –99 μm is about 90%. The size for producing Nb2O5-enriched slag, direct reduction fol- distribution of this applied ore is easy for pelletization. So lowed by magnetic separation is investigated in present the ore-coal composite pellets are used as the feed material work, which can give the theoretical references for industri- for direct reduction experiments. The goal of direct reduc- al application in future. tion is that the ferrous oxides are reduced to metallic iron, but the niobium oxides are not reduced (based on the ther- modynamic analysis).14) Then metallic iron can be separated 2. Experimental Design with slag by magnetic separation. The niobium oxides pres- 2.1. Raw Materials ent in slag. This slag is named as Nb2O5-enriched slag, in Almost over 90% of Nb2O5-bearing resources in China which the Nb2O5 content is increased. This Nb2O5-enriched are found in Baiyunebo deposit in the Inner Mongolia slag is a good feed for producing ferroniobium, metallic nio- Autonomous Region. In this study, Baiyunebo ore is used as bium, and rare earth etc. The chemical compositions of coal the Nb2O5-bearing raw material. The Nb2O5 content of orig- and bentonite used in present work are listed in Table 2. inal Baiyunebo ore is very low, only 0.4–0.7%. But with the Before the pelletization, the coal and bentonite are ground development of beneficiation technology, the grade of to –74 μm. 12,13) Nb2O5 can be increased to 4.32% (Table 1). From Table 1, in addition to the ferrous oxides and niobium oxides, 2.2. Experimental Procedure there are some SiO2, TiO2, CaO, MgO and some alkalis The key for selective reduction of ferrous oxides and nio- (Na2O and K2O). bium oxides in present work is not only to reduce iron Niobium does not occur freely in nature. It primarily co- oxides and no-reduce niobium oxides, but also the reduced exists in form of pyrochlore, a niobium-rich, complex min- metallic iron particles grow to big size which is benefit for eral containing some of calcium, sodium, titanium, rare the following step --- grinding and magnetic separation. earth and other elements. Pyrochlore is the most important Another key is that the pellet can not melt during the process mineral for niobium extraction and production. Niobium can of direct reduction. If melting, the process probably is diffi- also be found in columbite, which is a niobate of iron, man- cult to be realized in industrial trial. ganese, and magnesium. X-ray diffraction of the applied ore In order to get optimum operation parameters for the is shown in Fig. 2. From the figure, one can conclude that, selective reduction of ferrous oxides and niobium oxides, (1) our applied ore is composed of hematite, magnetite, series of direct reduction experiments were conducted. In quartz, and some complex mineral including Ti, Ca, Na etc. these series of experiments, the effects of following vari- (2) Hematite is the main ferrous oxide, and there is small ables on the reduction of ore-coal composite pellets were amount of magnetite. (3) The co-exist ore containing niobi- studied: um oxides and titanium oxides is the main Nb2O5-bearing (1) The processing temperature (the temperature in the ore. The co-exist ore and the compact structure are the main Muffle furnace) for reduction. Basically, higher temperature characteristics for niobium extraction and production. (4) will result in melting of pellets, and lower temperature will The slag is mainly composed of silicate and quartz. result in low metallization degree and low rate of reduction. The size distribution of Nb2O5-bearing ore is shown in (2) The reduction time. This is related to the reduction Fig. 3. From the figure, the powder of –50 μm is about 50%, temperature, and proper time will result in high degree of metallization and big size of metallic iron, which is benefit Table 1. Chemical composition of Nb2O5-bearing concentrate ore, mass%. 100 TFe FeO Nb2O5 CaO SiO2 MgO Al2O3 MnO 8 35.52 1.6 4.32 2.42 21.87 1.05 0.26 0.31 80 Cumulative percentage, % FSPNa2OK2OTiO2 Sc2O3 TREO 6 60 0.73 0.73 0.07 2.42 0.18 6.71 0.032 2.72 4 40 ͩ Size distribution, % 2 14000 ƹ Ʒ--Fe2O3 ƹ--Ti NbO4 20 Size distribution ƾ ƾ--Fe3O4 --Ca SiO4 ƽ Cumulative percentage Ƶ--TiO2 Ƽ--NaFeO Si2O6P 12000 --SiO2 0 0 ͩ 050100150200 ƽ 1 Ʒƹ Diameter, um ƾ 10000 Ʒ Ƽ Fig. 3. Size distribution of Nb2O5-bearing concentrate ore. Ƶ Intensity Ʒ Ʒ 8000 Ƽ Ʒ ͩ Ƶ ͩ Table 2. Chemical composition of coal and bentonite, mass%. 6000 Pulverized Fixed Carbon Total Carbon Volatile Matters Ash H2O 20 40 60 80 Coal 60.49 75.4 31.23 8.28 6.68 Angle, 2θ(deg.) SiO2 Al2O3 CaO MgO Bentonite 69.74 16.60 2.41 1.14 Fig. 2. X-ray diffraction of Nb2O5-bearing concentration ore. 1359 © 2013 ISIJ ISIJ International, Vol. 53 (2013), No. 8 for the following grinding and magnetic separation. Fig. 5. From the figure, one can conclude that the pellets (3) The amount of carbon addition, in term of the gram- will seriously melt when the temperature is higher than atomic of fixed carbon in the coal added to the gram-atomic 1200°C. According to the chemical composition of ore, the of combined oxygen in iron oxides, which is denoted as C/O dominant oxides in slag should be SiO2, TiO2, and Nb2O5.
Load more

Recommended publications
  • Laboratory Furnaces and Dryers
    CATALOG Laboratory furnaces and dryers Art of heating TABLE OF CONTENTS Our business partners 4 LAC – who we are 5 How to select a furnace 6 Choosing a furnace according to batch processing technology 8 Furnaces for temperatures 120 – 850 °C S – Dryers up to 200 and 300 °C 10 PP – Tempering furnace up to 450, 650 or 850 °C 12 Furnaces for temperatures 650 – 1340 °C PKR - Gas-tight chamber furnace up to 950 and 1100 °C 14 PKRC - Gas-tight chamber furnace with air circulation up to 950 and 1100 °C 16 LZ – Ashing furnace up to 1100 °C 18 LE – Economy laboratory furnace up to 1100 °C 20 L – Universal laboratory furnace up to 1200 °C 22 LMH – Horizontal muffle furnace up to 1200 °C 24 LMV – Vertical muffle furnace up to 1200 °C 26 LG - Gravimetric furnace up to 1200 °C 28 PKE - Hardening furnace up to 1280 °C 30 LT – Tube furnace up to 1300 °C 32 LSP – Five-zone gradient furnace up to 1300 °C 34 LH - Laboratory furnace up to 1340 °C 36 Furnaces for temperatures 1200 – 1800 °C LHS – Laboratory furnace with silit rods for up to 1400 and 1500 °C 38 VP – High-temperature furnace for up to 1600, 1700 and 1800 °C 40 Custom-made furnaces for special applications CHTZ - Small workplace for chemical heat treatment of non-ferrous materials up to 950 °C 42 SKM - Hardening work-station laboratory table up to 1340 °C 43 LH 30 atyp - Hardening furnace up to 1200 °C 44 L 09 atyp - Bottom-loading laboratory chamber furnace up to 1200 °C 45 PKE 25 atyp - Hardening chamber furnace with protective gas supply container up to 1200 °C 46 LT 50 atyp - Tube furnace with programmable servo-drive up to 1300 °C 47 LT 150 and LT 300 atyp - Activating tube furnace with glass retort up to 450 °C 47 LT 90 atyp - Tube furnace for mechanical testing of materials up to 1100 °C 47 Measurement and regulation 48 What (not) to choose – description of accessories 50 OUR PARTNERS 100 NEJLEPŠÍCH ČESKÝCH FIREM ROKU 2015 4 LAC – WHO WE ARE LAC – Who We Are We have over 240 employees and have produced more than 13,000 furnaces and dryers.
    [Show full text]
  • HISTORY of METALLURGY 2Nd Edition
    A HISTORY OF METALLURGY 2nd Edition A HISTORY OF METALLURGY Second Edition R. F. Tylecote MANEY FOR THE INSTITUTE OF MATERIALS Book B0789 First published in paperback in 2002 by Maney Publishing 1 Carlton House Terrace London SW1Y 5DB for the Institute of Materials First published in 1976 Reprinted in 1979 2nd edn published 1992 © The Institute of Materials 1992 All rights reserved ISBN 1-902653-79-3 Printed and bound in the UK by Antony Rowe Ltd v Contents Preface to the Second Edition vii Foreword viii Acknowledgements ix Introduction xi 1 Metals and ores in the Neolithic period 1 2 The technique and development of early copper smelting 7 3 The Early Bronze Age 18 4 The Full Bronze Age 35 5 The Early Iron Age 47 6 The Roman Iron Age 62 7 The Migration and medieval period 75 8 Post-medieval metallurgy 95 9 The Industrial Revolution; AD 1720-1850 122 10 More recent times; AD 1850-1950 164 11 The contributions of the scientists 177 Appendixes: 188 Technical Glossary 188 Note on units of weight, stress, and hardness 190 Table of elements 190 Approximate date of start of metal ages 191 Chinese chronology 191 Journals consulted and abbreviations 191 Principal works consulted 193 Maps 1-6 194-198 Subject and name index 199 vii Preface to the Second Edition The first edition was published in 1976 and an enormous increase in the general interest in the subject of archeometallurgy has taken place since then. Much of this relates to the early phases and has been discussed in Proceedings of International Conferences.
    [Show full text]
  • Carbothermic Reduction of Ore-Coal Composite Pellets in a Tall Pellets Bed
    minerals Article Carbothermic Reduction of Ore-Coal Composite Pellets in a Tall Pellets Bed Xin Jiang *, Guangen Ding, He Guo, Qiangjian Gao * and Fengman Shen School of Metallurgy, Northeastern University, Shenyang 110819, China; [email protected] (G.D.); [email protected] (H.G.); [email protected] (F.S.) * Correspondence: [email protected] (X.J.); [email protected] (Q.G.); Tel.: +86-24-83681506 (X.J.); +86-24-83691266 (Q.G.) Received: 19 October 2018; Accepted: 21 November 2018; Published: 27 November 2018 Abstract: Recently, increasing attention has been paid to alternative ironmaking processes due to the desire for sustainable development. Aiming to develop a new direct reduction technology, the paired straight hearth (PSH) furnace process, the carbothermic reduction of ore-coal composite pellets in a tall pellets bed was investigated at the lab-scale in the present work. The experimental results show that, under the present experimental conditions, when the height of the pellets bed is 80 mm (16–18 mm each layer, and 5 layers), the optimal amount of carbon to add is C/O = 0.95. Addition of either more or less carbon does not benefit the production of high quality direct reduced iron (DRI). The longer reduction time (60 min) may result in more molten slag in the top layer of DRI, which does not benefit the actual operation. At 50 min, the metallization degree could be up to 85.24%. When the experiment was performed using 5 layers of pellets (about 80 mm in height) and at 50 min duration, the productivity of metallic iron could reach 55.41 kg-MFe/m2·h (or 75.26 kg-DRI/m2·h).
    [Show full text]
  • Standard Muffle Furnace FO Series
    Standard Muffle Furnace FO Series Operating o Temp. control Internal 1.5L 3.75L 7.5L 9L 11.3L 17.5L 23.6L 30L 100~1150 C ±2°C (at 1150°C) temp. range accuracy capacity (FO100CR/110CR) (FO200CR/210CR) (FO300CR/310CR) (FO410CR) (FO510CR) (FO610CR) (FO710CR) (FO810CR) Wide selection of space-saving compact units with maximum inner capacity Easy to use controller Excellent heat tightness with a firmly sealed chamber door High temperature accuracy at ±2.0°C Program operation of maximum of 6 patterns: 30 steps x 1 pattern, 15 steps x 2 patterns or 10 steps x 3 patterns Safety features include self-diagnostic functions, calibration off-set, lock function, auto-recovery after power failure, earth leakage breaker and automatic overheat prevention device Selectable options include exhaust system 1.5L 9L 11.3L 30L unit, N2 gas loading device (with flow meter), FO110CR FO410CR FO510CR FO810CR temperature output terminal, time up / alarm output terminal and sample tray Upgraded with long life R-thermocouple sensors Designed with communication port Specifications Model FO100CR/110CR FO200CR/210CR FO300CR/310CR FO410CR FO510CR FO610CR FO710CR FO810CR Operating temp. range 100~1150oC Temp. control accuracy ±2oC (at 1150oC) Max. temp. reaching time ~60min. ~70min. ~80min. Exterior material Cold rolled steel plate with baked-on melamine resin finish Internal material Ceramic fiber Sensor R-thermocouple Heater Iron-chrome wire 1kW 1.5kW 2kW 2.2kW 2.5kW 3kW 3.5kW 4kW Exhaust port ø20mm (top) Cooling Fan Type Axial fan motor Temp. controller PID controll by microprocessor Temp. setting/display method Digital setting by▲/▼ keys / Digital display Operation function Fixed temperature, quick auto stop, auto stop, auto start, program (maximum 6 patterns: 30 steps x 1 pattern, 15 steps x 2 patterns or 10 steps x 3 patterns) Additional function Calibration offset, power failure compensation, lock, RS485 communication interface Timer 1 min.
    [Show full text]
  • Transactions
    52-5 TRANSACTIONS OF THE AMERICAN INSTITUTE OF MINING ENGINEERS. VOL. IV. MAY, 1875, TO FEBRUARY, 1876. EASTON, PA.: PUBLISHED BY THE INSTITUTE, AT THE OFFICE OF THE SECRETARY, LAFAYETTE COLLEGE. PHILADELPHIA: SHERMAN & CO., PRINTERS. CONTENTS. PAGE OFFICERS AND MEMBERS,.......................................................................v-xx RULES, ................................................................................................... xxi DOVER MEETING, May, 1875,........................................................................3 CLEVELAND MEETING, October, 1875,........................................................... 9 WASHINGTON MEETING, February, 1876....................................................... 1 8 DOVER MEETING. Repairing the Upper Part of a Furnace Lining, without Blowing Out. By FRANK FIRMSTONE, ....................................................................29 On the Use of Natural Gas for Puddling and Heating, at Leechburg, Penn- sylvania. By A. L. HOLLEY, C.E.,...................................................... 32 The Swansea Silver Smelting arid Refining Works of Chicago. By .J. L. JERNEGAN, JR., M.E., ...........................................................................35 Fires in Mines. Their Causes and the Means of Extinguishing Them. By RlCHARD P. ROTHWELL, M.E.........................................................................54 CLEVELAND MEETING. Some Pressing Needs of Our Iron and Steel Manufacture. By A. L HOL- LEY,C.E.,...........................................................................................................
    [Show full text]
  • New Developments in Advanced Highestrength
    NEW DEVELOPMENTS IN ADVanCED HIGH-STRENGTH ShEET STEELS 30 MAY–2 JUNE 2017 KEYSTONE RESORT & CONFERENCE CENTER KEYSTONE, COLO., USA ABOUT THE PROGRAM Advanced high-strength sheet steels (AHSS) are of increasing importance, particularly to the automotive industry, where their application enables reduced fuel consumption while guaranteeing passive safety. The scope of the conference is to bring together the international community to highlight state-of-the-art research and development pertaining to AHSS. The conference will focus on the latest developments in dual phase, twinning-induced plasticity, martensitic, quenched and partitioned, medium-manganese steels, other third-generation AHSS concepts and hot-stamped steels along with recent experiences with industrial implementation and end-user application performance. A broad distribution of presentation topics is scheduled from international and domestic speakers from industry as well as academia. The conference is the latest installment in a series of product-specific conferences following the AHSS symposia in Winter Park, Colo., in 2004, Orlando, Fla., in 2008 and Vail, Colo., in 2013. WHO SHOULD ATTEND The conference should be attended by steel researchers interested in new high- strength sheet steel products, along with engineers responsible for the production and implementation of the products in steel mills, automotive facilities, and other industries, along with government and academic professionals and students. Visit AIST.org/byoyp for more information ORGANIZED BY AIST’s Metallurgy — Processing, Products & Applications Technology Committee and The Colorado School of Mines’ Advanced Steel Processing and Products Research Center. ScHEDULE OF EVENTS TUESDAY, 30 MAY 2017 4–6 p.m. 6 p.m. Registration Reception WEDNESDAY, 31 MAY 2017 7 a.m.
    [Show full text]
  • Effect of Heat Treatment Method on the Hardness and Corrosion of Ductile Iron in 3.5% Sodium Chloride Solution
    International Journal of Advanced Academic Research (Sciences, Technology and Engineering) | ISSN: 2488-9849 Vol. 6, Issue 9 (September, 2020) | www.ijaar.org Journal DOI: 10.46654/ij.24889849 Article DOI: 10.46654/ij.24889849.e698 EFFECT OF HEAT TREATMENT METHOD ON THE HARDNESS AND CORROSION OF DUCTILE IRON IN 3.5% SODIUM CHLORIDE SOLUTION Oluyori, R. T1; Alao, A. O2; Barnabas, A. A3; Shittu, S. A3; Omole, S. O3 and Akinwande, A. A3 1 Department of Metallurgy and Materials Engineering, Kogi State Polytechnic, Lokoja, Kogi State, Nigeria. 2Department of Foundry Engineering, Federal Polytechnic, Idah, Kogi State, Nigeria . 3Department of Metallurgical and Materials Engineering, Federal University of Technology, Akure, Nigeria. Corresponding author’s email: [email protected] Abstract In this research, the corrosion response of heat treated ductile cast iron (DCI) used in the production of engine crank shaft was examined. Five samples were used in this work, one of the samples served as control sample, the remaining four samples were subjected to conventional heat treated operations of annealing, normalizing and hardening. The nodular cast irons were heated to initial austenitic temperature of 900°C, held for one (1hour) in the muffle furnace for homogenization, and samples were now cooled in furnace, air, water and oil respectively. Sodium chloride of 3.5% weight percentage solution was used as environment to study corrosion behaviour of the heat treated ductile cast irons. The microstructural images of the control and heat treated samples were resolved and various developed structures are essentially spheroidal graphite, and pearlitic matrix as in the case of the un-heat treated sample, coarse pearlite matrix for the annealed sample, fine pearlite structure for the normalized sample and partially martensitic and fully martensitic matrix for the oil and water quenched samples.
    [Show full text]
  • Production of Chromium Boride Layers on Carbon Steel with Conversion Treatment: Chromium Deposition + Diffusion Annealing R
    Vol. 132 (2017) ACTA PHYSICA POLONICA A No. 3 Special issue of the 3rd International Conference on Computational and Experimental Science and Engineering (ICCESEN 2016) Production of Chromium Boride Layers on Carbon Steel with Conversion Treatment: Chromium Deposition + Diffusion Annealing R. Boubaayaa;∗, Y. Benariouab, O. Allaouia and M. Djendela aLaboratoire Génie des Procédés, Université de Laghouat, BP 37G, Laghouat, Algeria bDépartement de Génie Mécanique, Faculté de Technologies, Université de M’Sila, BP 166, M’Sila 28000, Algeria The present study has been conducted in order to obtaining chromium boride layers on carbon steel using a conversion processing comprising the following steps: boriding treatment in order to increase the amount of boron atoms in the steel surface, deposition of a thin layer of pure chromium using electrolytic method, and finally an annealing treatment for boron diffusion and formation of boride layer until complete transformation of chromium layer. Depending on the method used (chromium deposition followed by boriding or boriding followed by chromium deposition) and the holding time, the partial or complete conversion is obtained as a result of the diffusion process. The role of the annealing temperature on transformation rates of chromium into chromium boride films was investigated. It is shown that for 1 h at 900 ◦C, the chromium layer is totally transformed. The scanning electron microscopy analysis and X-ray diffraction showed the presence of CrB and CrB2 chromium borides in addition of FeB and Fe2B iron borides. DOI: 10.12693/APhysPolA.132.541 PACS/topics: carbon steel, boriding, chromium plating, diffusion annealing, chromium boride 1. Introduction of increase of the boron content at the surface of the sub- strate using a standard boriding process.
    [Show full text]
  • Heat Treatment Laboratory Manual
    HEAT TREATMENT LABORATORY MANUAL Er. SUBRAT KUMAR BEHERA Lecturer in Metallurgy DIPLOMA (3rd YEAR-5th SEMESTER) Department of Metallurgical Engineering ORISSA SCHOOL OF MINING ENGINEERING, KEONJHAR A Government of Odisha institution with National Repute Established in the Year 1956 (Approved by AICTE, New Delhi & Affiliated to SCTE&VT, Odisha,BBSR) HEAT TREATMENT PROCESSES In general, heat treatment can be defined as an operation, or the combination of operations that involve heating and cooling of a metal in solid phase to obtain certain required properties. The ferrous materials can be heated to above transformation temperature and can be heat – treated to obtain different structure. The different heat treatment processes are based on heating the material to certain temperature and employing different cooling rates. In this process, heating temperature and rate of cooling adopted plays an important role. The different processes are: Annealing • Stress-relief annealing. • Process annealing. • Spheroidsing. • Full annealing. Normalizing Hardening(Quenching) Tempering Austenite, also known as gamma phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of carbon in gamma iron (γ-Fe). It forms above 7230C. It has a FCC crystal structure. The maximum solubility of carbon in austenite is 2.13 % at 1147Oc Fig: - Iron- Carbon Diagram EXPERIMENT-1 Aim: - Annealing of plain carbon steel Apparatus Required: - Hacksaw blade Plain Carbon Steel (Mild Steel) Sample Muffle Furnace File Emery Paper Double disc polisher Etchant (Nital) [98% C2H6OH + 2% HNO3] Metallurgical Microscope Theory: - Annealing generally involves heating to a predetermined temperature, holding at this temperature and finally cooling at a very slow rate The temperature and holding time depend on a variety of factors such as composition, size, shape and final properties desired Annealing treatment can be classified into subdivisions based on temperature of treatment, phase transformation occuring during the treatment and the purpose of the treatment.
    [Show full text]
  • Iron Recovery from Bauxite Tailings Red Mud by Thermal Reduction with Blast Furnace Sludge
    applied sciences Article Iron Recovery from Bauxite Tailings Red Mud by Thermal Reduction with Blast Furnace Sludge Davide Mombelli * , Silvia Barella , Andrea Gruttadauria and Carlo Mapelli Dipartimento di Meccanica, Politecnico di Milano, via La Masa 1, Milano 20156, Italy; [email protected] (S.B.); [email protected] (A.G.); [email protected] (C.M.) * Correspondence: [email protected]; Tel.: +39-02-2399-8660 Received: 26 September 2019; Accepted: 9 November 2019; Published: 15 November 2019 Abstract: More than 100 million tons of red mud were produced annually in the world over the short time range from 2011 to 2018. Red mud represents one of the metallurgical by-products more difficult to dispose of due to the high alkalinity (pH 10–13) and storage techniques issues. Up to now, economically viable commercial processes for the recovery and the reuse of these waste were not available. Due to the high content of iron oxide (30–60% wt.) red mud ranks as a potential raw material for the production of iron through a direct route. In this work, a novel process at the laboratory scale to produce iron sponge ( 1300 C) or cast iron (> 1300 C) using blast furnace ≤ ◦ ◦ sludge as a reducing agent is presented. Red mud-reducing agent mixes were reduced in a muffle furnace at 1200, 1300, and 1500 ◦C for 15 min. Pure graphite and blast furnace sludges were used as reducing agents with different equivalent carbon concentrations. The results confirmed the blast furnace sludge as a suitable reducing agent to recover the iron fraction contained in the red mud.
    [Show full text]
  • Thermo Scientific Heraeus® High Temperature Furnaces
    Thermo Scientifi c Heraeus® High Temperature Furnaces Precisely the heat you need Thermo Scientific Heraeus Thermo Scientific Heraeus High Temperature Furnaces K 114 Chamber Furnace Performance you can count on – The ideal choice for everyday use year after year Thermo Scientifi c Heraeus High Tempe- • Extremely short heating and rature Furnaces are designed to meet recovery times – Annealing chamber made of ceramic fi ber for the stringent demands of today‘s labora- rapid heat-up and recovery times. tory. The range delivers precise and repro ducible temperature performance. • Accurate temperature control – Outstanding temperature distribu- Made in Germany, our furnaces provide tion and control ensure effi cient superior long-lasting reliability and state- operation. of-the-art safety. Powerful and sturdy, they require little energy. • Ideal for use in crowded laboratory – Compact size, excellent insulation and patented safety door mechanism. Long term experience • Common application areas – Uses include materials testing, burning and rapid heat processes. We have over 80 years experience in the design and manufacture of high temperature furnaces. Our extensive installed base is testament to our exper- tise and product reliability. High temperature, high quality in a compact package Safe to use • Operates at 1100 °C A wide range of safety features includes • Choose from a variety of models with extra-features • Oven doors designed so the hot side and options: always faces away from the operator • 24-hour timer • Effi cient insulation for low outside • Thermicon P digital program controller surface temperatures with microprocessor • Automatic interruption of the heating • Exhaust fan system when door is opened • Exhaust fl ue • Upper limit cut-out automatically • Adjustable fresh air supply switches off heating in case of over temperature Convenience Thermo Scientifi c furnaces are equip- ped with easily accessible control elements and a digital display.
    [Show full text]
  • Thermal Process Technology
    Thermal Process Technology Furnaces and Heat Treatment Plants for Processes under Protective or Reactive Gases or Vacuum Retort Furnaces Continuous and Wire Annealing Furnaces Tube Furnaces Salt-Bath Furnaces Nitriding and Caburizing Furnaces Furnaces for Additive Manufacturing Hardening Systems, Quenching Baths Protective Gas Boxes Made in www.nabertherm.com Germany Made in Germany Nabertherm with 500 employees worldwide have been developing and producing industrial furnaces for many different applications for 70 years. As a manufacturer, Nabertherm offers the widest and deepest range of furnaces worldwide. 150,000 satisfied customers in more than 100 countries offer proof of our commitment to excellent design, quality and cost efficiency. Short delivery times are ensured due to our complete inhouse production and our wide variety of standard furnaces. Setting Standards in Quality and Reliability Nabertherm does not only offer the widest range of standard furnaces. Professional engineering in combination with in house manufacturing provide for individual project planning and construction of tailor-made thermal process plants with material handling and charging systems. Complete thermal processes are realized by customized system solutions. Innovative Nabertherm control technology provides for precise control as well as full documentation and remote monitoring of your processes. Our engineers apply state-of-the-art technology to improve the temperature uniformity, energy efficiency, reliability and durability of our systems with the goal of enhancing your competitive edge. Global Sales and Service Network – Close to you Nabertherm´s strength is one of the biggest R&D department in the furnace industry. In combination with central manufacturing in Germany and decentralized sales and service close to the customer we can provide for a competitive edge to live up to your needs.
    [Show full text]