Design, Fabrication and Construction of Cupola Furnace for Metallurgical Industries

ISSN: 2689-1204

Research Article Journal of Applied Material Science & Engineering Research Design, Fabrication and Construction of Cupola Furnace for Metallurgical Industries

Ocheri C

Department of metallurgical and Materials Engineering, University *Corresponding author of Nigeria, Nsukka, Nigeria Ocheri C, Department of metallurgical and Materials Engineering, University of Nigeria, Nsukka, Nigeria Submitted: 10 Sept 2020; Accepted: 16 Sept 2020; Published: 13 Oct 2020

Abstract A 350 kilogram per hour capacity Cupola Furnace was designed and fabricated from locally available materials for the production of cast iron using pig iron, oily or contaminated steel scraps, foundry returns and fluxes. The main fuel used is metallurgical coke. After analyzing the design parameters, the metallic shells were fabricated in four segments for easy lining: the stack zone, preheating zone, combustion zone and the hearth. Mild steel sheet of 4 mm thickness was procured, marked out as per the design drawing, sliced, rolled into cylindrical shapes and welded together at each seam. The internal configuration was lined first with asbestos paper measuring 4 mm thick using water-glass to enable it adhere to the internal shell of the segments, thereafter, a less dense insulating refractory material was used and finally fireclay refractory bricks were used for lining as they interface directly with the molten metal. The various segments were then assembled and erected with the blower connected to the combustion zone. The research work also contains the materials and components bill.

Keywords: Assembling, Cupola-furnace, Design, Fabrication, 1.5Cr) hardness thus obtained is of the order of 700 Brinell. This Refractories being almost un-machineable. It is used in parts requiring high abrasion resistance. Introduction Cupola furnace is a melting device used in foundries majorly to Cupola furnace is similar to a small blast furnace. It is cylindrical produce cast iron and bronzes. It is a continuous melting shaft in shape and the cambers are arranged vertically. It is usually furnace capable of processing different range of raw materials fabricated with mild steel (flat sheet plates) and special clay or from pig iron, oily and contaminated scraps, foundry returns and refractory bricks are used as inner lining materials. It utilizes coke ferroalloys [1]. Its main energy source is metallurgical coke. It is & limestone as the main source of fuel and fluxing agent one of the oldest methods of producing cast iron, and it remains respectively. The furnace is mainly used, for the casting of grey the dominant method because of its simplicity and low fuel cost. cast iron and for the casting of white or chilled cast iron. Grey cast The size of a cupola is expressed in diameter and can range from iron is produced by melting together low quality foundry pig iron 0.5 m to 4 m [5]. The overall shape is cylindrical and the equipment scrapped casting and coke in a cupola. The fractured of this type of is arranged vertically, usually supported by three or four legs. The cast iron gives a grey appearance and has got most of its carbon in overall look is similar to a large “smokestack” [5]. The bottom of a graphite form. Hence, it is soft, easily machinable metal with the cylinder is fitted with doors, which swing down and out to high damping capacity and high compressive strength. It has self- “drop bottom”. The top where gases escape can be open or fitted lubricating characteristics. with a cap to prevent rain from entering the cupola. To control emissions, a cupola may be fitted with a cap that is designed to White or chilled cast iron: same mode of production as grey cast pull the gases into a device to cool the gases and remove particulate iron but has no graphite and is, therefore white in color. The whole matter [9]. of carbon content in this type of cast iron is in the form of either free cementite or cementite in lamellar pearlite. White cast iron is The shell of the cupola being usually made of steel has refractory very hard, brittle and wear resistant iron. Hardness of 400 Brinell brick and plastic refractory patching material lining it. The bottom is can be obtained by keeping silicon below 1%, carbon to about 2% lined in a similar manner but often a clay and sand mixture (“Bod”) in cast iron the toughness and strength of white cast iron is doubled may be used, as this lining is temporal. Finely divided coal (sea coal) by small additions of Nickel, and chromium (e.g. 4.5% Ni and can be mixed with the clay lining so that when heated the coal J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 134 decomposes and the bod becomes slightly friable, easing the opening and coke are added until the level reaches the charging doors. The up of the tap hole. The bottom lining is compressed or rammed against metal charged would consist of pig iron; scrap steel and domestic the bottom doors [1]. Some cupolas are fitted with cooling jackets to returns [8]. keep the sides cool and with oxygen injection to make the coke fire burn hotter. Additionally, the cupola is a counter flow vertical shaft An air blast is introduced through the wind box and tuyeres located furnace and offers the high possibility of good melting efficiency near the bottom of the cupola. The air reacts chemically with the compared with batch type melters [2]. carbonaceous fuel thus producing heat of combustion. Soon after the blast is turned on, molten metal collects on the hearth bottom The current growing rate of unemployment became more where it is eventually tapped out into a waiting ladle or receiver. pronounced because most of our indigenous companies are in As the metal is melted and fuel consumed, additional charges are comatose simply because of non-availability of fast wearing spare added to maintain a level at the charging door and provide a parts. Therefore, the design and fabrication of cupola furnace continuous supply of molten iron. using locally sourced materials and indigenous technology will ameliorate the situation thereby making it easier for metallurgical At the end of the melting campaign, charging is stopped but the air institutions to cast simple and complex spare parts to keep our blast is maintained until all of the metal is melted and tapped off. industries functional. It will also assist research engineers to The air is then turned off and the bottom doors opened allowing further their research with a view to improving the quality of the residual charge material to be dumped [10]. products and develop new materials. Materials and Methods Working Principles of the Cupola Furnace Materials For many years, the cupola was the primary method of melting The materials utilized for the design and fabrication of cupola used in iron foundries. The cupola furnace has several unique furnace are: mild steel plates, steel angle bars, steel pipes, M24 characteristics, which are responsible for its widespread use as a bolts and nuts, asbestos sheets, less dense/insulation refractory melting unit for cast iron. bricks, dense refractory bricks (fireclay), electric centrifugal (i) The cupola is one of the only methods of melting which is blower, refractory cement, magnesite powder, zircon sand and continuous in its operation water glass (sodium silicate, Na₂SiO₃). (ii) High melt rates (iii) Relatively low operating costs Cupola Furnace Design and Material Selection (iv) Ease of operation Considerations The main parts of the cupola furnace are the vertical steel shell The construction of a conventional cupola consists of a vertical (comprising the well/hearth, combustion/melting zone, preheating steel shell, which is lined with refractory bricks. The charges are zone and charging zone), the tuyeres, electric centrifugal blower and introduced into the furnace body by means of an opening the bottom cover. The design of the cupola furnace is based on approximately half way up the vertical shaft. The charges consist considerations and functionality of the various components/parts, of alternate layers of the metal to be melted, coke fuel and design cost, local availability of materials/components, availability of limestone. The fuel is burnt in air, which is introduced through fuel and the ease of fabrication process and the lining of the internal tuyeres positioned above the hearth. The hot gases generated in the wall. Figures 1-8 show various parts of the furnace while figure 9 lower part of the shaft ascend and preheat the descending charge [4]. shows the 2D CAD view of the cupola furnace is presented in Fig. 1

The cupola is of the drop bottom type with hinged doors under the hearth, which allows the bottom to drop away at the end of melting to aid cleaning and repairs. At the bottom front is a tap hole for the molten iron at the rear, positioned above the tap hole is a slag hole. The top of the stack is capped with a spark/fume arrester hood.

The internal diameters of cupola are 380 mm which can be operated on different fuel to metal ratio, giving melt rates of approximately 350 kilograms per hour.

The operation cycles for the cupola, consist of closing and propping the bottom hinged doors and preparing a hearth bottom. The bottom is usually made from low strength moulding sand and slopes towards the tapping hole. A fire is started in the hearth using lightweight timber; cokes are charged on top of the fire and is burnt by increasing the air draught from the tuyeres. Once the coke bed is ignited of the required height, alternate layers of metal, flux Figure 1: Shows the collection of Chambers

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Figure 5: shows the Charging Chamber Figure 2: shows the Melting Chamber

Figure 3: Development of the Melting Chamber Figure 6: shows the Flanges

Figure 4: shows the Pre –heating Chamber Figure 7: Shows the Air Trapped Cover

J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 136 with spy holes in order for the operator to view the melting operation within the combustion zone. A hinged door is attached to the bottom of the furnace to allow for ramming of bottom sand when closed preserving the molten cast iron to accumulate before tapping and be used to discharge the cinders when the melt is over. Hardwood, firewood cut to sizes were craftily arranged diagonally at the hearth of the furnace in between the upper and lower row of the tuyeres in the combustion zone. The firewood burns to ignite the metallurgical coke thereby establishing coke bed that is strong enough to carry the burden and subsequently melts it to molten state. The charge materials are pig iron; steel scraps, foundry returns, flux (limestone) and metallurgical coke as fuel are loaded continuously until it reaches the charging door. The well/hearth was designed with tapping spout and slag spout by its side through which the slag and molten metals are tapped respectively. The tapping spout plugged with clay bod was pierced through before tapping. Figure 8: Shows the Melting Pipe of the Tuyeres Design Consideration and Calculations for the Cupola Height According to [2], the height of cupola furnace is normally stated relative to its diameter. This ranges between 4D to 6D and for small cupola furnace, 5D is recommended. The effective height of cupola, H, is the distance between the axis of the lower row of tuyeres and the charging door.

Therefore, effective height, H, of cupola furnace using 5D as recommended [2] is as shown in equation 2.1 H = 5D 2.1 Where H = Effective height D = Cupola furnace diameter Given D = 284 (after lining its interior) From eq 2.1, H = 5 x 284 or 1420 mm or 1.420 meters

The Tuyeres Figure 9: Shows the 2D CAD view of the assembled cupola The function of the tuyeres is to conduct equal quantities of air furnace from the wind box into the cupola furnace in order to produce uniform combustion condition through the coke bed. The tuyeres The Vertical Steel Shell will be sufficiently large to prevent any serious loss of pressure The vertical steel shell is an assemblage of various zones that through them and will not have any very drastic throttling effect makes up the cupola furnace wherein the melting of the charge on the blower. By selecting the tuyere area within the range, material takes place to produce cast iron. Mild steel plates were recommended, sufficient surplus area is made available to enable selected for the design, as it requires a material with good strength one or more of the tuyere to be reduced in area to correct poor blast and ability to withstand heat radiation. In addition, the excellent distribution. formability and weldability of mild steel were taken into consideration in selecting it for the design of outer shell. The Design Consideration and Calculation for Tuyeres design of the cupola furnace was done taking into consideration This was designed in two steps, the area and the required number the need to ensure the metallic shell is well lagged to check heat of tuyeres. The tuyere is based on the internal diameter of the loss and protect the outer shell with insulating materials like cupola furnace at the tuyere level. Standard ratios for small cupola asbestos sheet, less dense insulating refractory bricks and dense ranges from ⅙ to ¼ of the cross sectional area of the cupola refractory bricks (fireclay) that interfaces with the molten metal. Tuyere area can be calculated as follows: The wind box/combustion zone connected to the electric centrifugal blower was made airtight for effective delivery of air Using the ratio ⅙, the cross sectional area at tuyere level according blast into the melting zone to support combustion. The tuyeres to [2]. through which air is blasted into the cupola furnace was provided Tuyere area, At = ⅙Ac 2.2

J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 137 Where; Table 2.1: Blower Sizes for Cupola Operation

Ac = Cross Sectional area of Cupola (m²) or Area of well Inside Diameter Area Actual Recommended Blower Discharge 2 At = Cross sectional area of Tuyeres in (inches ) (inches) cfm size (cfm) m3/min. pressure Oz 2 10 78.5 216 6.12 8 Also, Ac = π ( ) 2.3 18 254 700 19.82 16 Number of Tuyere 23 415 1140 32.28 20 Source: [2] Cupolas of 250 mm – 700 mm diameter have four tuyeres in each row [6]. The number of tuyeres for the 500 mm cupola is four. Table 2.2: Blower Specification Therefore, the cross sectional area of the combined four tuyeres is S/N Parameters Quantity/Units 0.008m² (8000mm²). 1 Number of blades 6 The cross sectional area of each of the four tuyeres is 81704 = 2 Rotated speed 2890 – 3470 rpm 2042.5 mm² or 0.0020425 m² 3 Volume flow rate 1179 – 2062 m³/hr 4 Rated voltage 220 V Tuyere Pipe Thickness 5 Pressure 2840 – 2340 Kpa At = Cross sectional area of Tuyeres 6 Diameter of discharge pipe 95 mm

Given, cross sectional area of each tuyere, At = 2042.5 mm² 7 Overall dimension 690 mm x 640 mm x 910 mm 2 8 Rated power 5.5 Kw But At = π ( ) Also; π ( ) 2 = 2042.5 mm² Selection of Refractory Lining Source: Stewart 1996. Hence, D = √ (2042.5 × 4)/3.142 t The selection of refractory lining for any particular application is =50.993 mm 51 mm made with a view to achieving the best performance of the furnace. Therefore, Tuyere diameter = 51 mm (steel pipe of diameter 51 The type of furnace and the prevailing conditions; e.g., the gaseous ≅ mm) atmosphere, the presence of slag, the type of metal charged and cost considerations [3] determine the choice of the refractory Effective/Useful height of the cupola well material for a given application. The assessment of the desired The effective height of the cupola furnace is that portion of the properties would provide guidelines for selection of proper cupola between the tuyeres and the sand bottom. It serves to refractory materials. collect the molten metal and slag melted in the upper part of the furnace and permits the two to separate. In estimating the holding Refractory lining capacity of the well/hearth, it is usual to regard its effective height The cupola furnace internal shell was lined on the inside first with as the distance between the sand bottom and the slag hole located asbestos sheet followed closely by less dense insulating refractory at the rear directly opposite the tap hole [10]. and lastly firebricks refractory. It was chosen because of its ability to withstand mechanical impact of the charging material, the Mass of Charge Material chemical action of the liquid slag and gases. The joints between The mass of charge material is given [2] as; the bricks were kept as thin as possible to disallow slag attacking the joints that may lead to poor lining life. Each course was M = x VE 2.4 3 3 carefully laid and a minimal gap left between the bricks and the Where:푐푚 = density of Iron = 7.6 g/ = 7600kg/ 휌푟 shell that was filled with ganister/sand to take up expansion of the 2 VE = effective휌푟 volume of surface = π푐푚 ( ) H = 0.0461푚 ³ = bricks and prevent hot spots on the shell should there be metal 7600 × 0.0461 = 350 푐푚 penetration at the joints in the brickwork. 푚 ∴ 푀 About 350kg/hr, melt rate is the capacity of the cupola furnace 퐾푔 Insulating Refractory Parameter for Cupola Blower Selection Insulating refractory was used to minimize heat loss and to achieve The recommended blower size (Z) [2] is modified as follows heat conservation in the cupola furnace. They have high porosity, low thermal conductivity and high thermal insulating properties. Z = 111 A m3/min16. c The use of insulating refractory minimizes fuel consumption 3 = 111 × 0.049 = 5.43 m / leading to high production because of maintaining higher working 2 Where Ac = 0.049 m temperature and better working condition for the workers on the 푍 푚푖푛 Blowers are frequently sized up 10% to make up for leaks in the shop floor. system and variations in temperature. Cost Analysis The recommended blower sizes for Cupola based on the furnace The entire materials and equipment used for the fabrication of the diameter are presented in Table 2.1 and the blower specification is cupola furnace are presented in Table 2.3. The materials and given in Table 2.2. equipment used in the design were locally sourced and the overall

J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 138 cost of designing and fabricating the cupola furnace is costs N8,500,000.00, ($23,611.00 at N360/$) [7], for both approximately N1, 154,006.00 ($3,205.57 at N360/$). The cupola transportation and clearing. furnace is cheap in comparison to similar design from abroad that

Table 2.3: Bill of Engineering Materials Evaluation Sno Material Description Quantity Unit Cost Total Cost 1 Mild Steel sheet 5 mm X 1200 X 24000 4 sheets 15,000.00 60,000.00 2 Steel pipe (Ø64 X 400 mm X 8 nos) 3.2 meters 500 4,000.00 3 Blower pipe (Ø127 X 1 meter) 1 meter 3,500.00 3,500.00 4 Welding Electrodes - gauge 10 3 packets 2,500.00 7,500.00 5 Welding Electrodes - gauge 12 1 packet 2,600.00 2,600.00 6 Grinding disc 3 nos 500.00 1,500.00 7 Cutting disc 6 nos 500.00 3,000.00 8 Base plate for the bottom door Ø675 mm 2,500.00 2,500.00 9 Angle bar: 5 mm X 65 mm X 65 mm 1 piece 3,500.00 3,500.00 10 Firebricks lining (50 X 100 X 188) 288 piece 288,000.00 11 Steel pipe (Ø75 mm X 1500 mm X 3 nos) 4,500 mm 7,500.00 12 7.5 Kw Blower (Three-phase) 1 no 155,000.00 155,000.00 13 Fireclay cement 10 bags 5,000.00 50,000.00 14 Design cost 120,000.00 15 Plotting of design drawings 15,000.00 16 Welding of the entire shell 25,000.00 17 Transportation of cupola and accessories to site 45,000.00 18 Painting of the cupola furnace 10,000.00 19 Pig iron for test running 1 ton 79,891.00 79,891.00 20 Steel scrap (crop ends) 0.4 ton 60,000.00 24,000.00 21 Lime stone 0.2 ton 15,000.00 3,000.00 22 Ferro-alloys ( Fe-Si, Fe-Mn, Fe-Cr) 0.1 ton 285,150.00 28,515.00 23 Metallurgical coke 1 ton 35,000.00 35,000.00 24 Labour cost (erecting, concreting the platform and electrical work 180,000.00 TOTAL 1,154,006.00

The Cupola purpose is to supply air evenly to the tuyeres, which are the Cupola furnace is a shaft furnace of cylindrical shape erected on openings that extends through the steel shell and refractory wall to three legs or columns mounted on a concrete base. Doors hinged the combustion zone; the tuyeres are arranged above the cupola to the bedplate close the bottom of the furnace. These doors are well (the lower part of the cupola from sand bottom to tuyeres is closed and locked by a locking rod or a prop during the melting called well). The bottom of the cupola is rammed of weak operation. The shell is made of steel plate 15mm thick. The interior moulding sand possessing high refractoriness. is lined with refractory bricks (firebricks) by the Refractory Maintenance unit of Ajaokuta Steel Company Limited (ASCL) to Cupola Operation protect the shell from being overheated and burn off. The charge The bottom doors were closed and held shut by means of locking for the cupola consists of metallic materials, fuel (coke) and rod designed solely for the purpose. A Layer of ordinary moulding fluxes. The metallic part of the charge is made up of definite sand about 150mm thick is placed over the doors and sloped quantities of pig iron of various grades, cast iron and steel scrap, towards the tap hole. In firing a cupola, fire of kindling wood is foundry scrap (gating’s, splashes, spills, rejects and chips) and started on the sand bottom, coke is then added in several portions calculated amount of Ferro-alloys. The metallurgical coke is used to a level slightly above the tuyeres and the air blast is turned on at as fuel for melting the metallic charge, the fluxes (lime/dolomite, a lower than normal blowing rate. This intensifies coke combustion CaO/MgCO₃) melt and reacts with contaminants and non-metallic and then new portions of coke are charged into the cupola to reach elements and inclusions; the resulting slag (calcium silicate) floats a height of 600mm to 800mm above the tuyeres. This layer of to the surface of the melt and is removed through the slag hole. coke is called the “coke bed”, the height of the coke bed is very important to the cupola process. It affects the temperature, melting The solid materials (metal, coke, flux) are charged into the cupola rate and chemical compositions of the cast iron tapped from the from the charging door. Air for the combustion of fuel is delivered cupola. As soon as the coke bed is thoroughly ignited, alternate from a blower and enters a chamber called “wind box”, the wind charges of iron, limestone and coke are added in weighted portions box completely encircles the melting chamber of the cupola. Its until level with the charging door. J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 139 Full blast delivered to the tuyeres from the blower is turned on layers of charge and the temperature here is up to 1090˚C. after completely charging the cupola. The first molten metal would appear at the tapping hole after within 5 to 10 minutes of charging. Conclusion When the well of the cupola becomes full, the slag is first drained This research work has made available a functional cupola furnace off through the slag spout and for intermittent tapping; the tap hole of 350 kilograms per hour capacity of molten cast iron. A cue was is closed with lump of sand bed clay called a “bot”. For tapping, taken from the cupola furnace of Foundry Shop, Ajaokuta Steel the bot is punctured through with a long bar and the molten cast Company Limited and the Foundry Shop in the Department of iron flows out the tap hole into a handling ladle (hand shank). Metallurgy and Materials Engineering, Federal University of When the molten metal is completely emptied, another bot is Technology, Akure. To make the refractory lining a neutral rammed into the tap hole to accommodate another melt. As the environment by enabling it operate in acidic and basic environment cupola is operated, additional charges of limestone, iron and coke without a marked reaction, zircon sand was used on the interface are charged through the charging door when there is sufficient heat at a lesser cost and to extend the life span of the lining. Cupola also for them. facilitate the ease of obtaining cast iron melt at reduced cost and it would stimulate small scale entrepreneurship thereby generating Various Zones in The Cupola Are revenue and conserving foreign exchange by playing an important Well or Crucible role in metal recycling industry because of its inherent This is the chamber that rests directly on the bottom doors wherein characteristics. The design and fabrication of the cupola furnace the molten metal and slag collects and is separated, the slag being locally is a worthwhile project in that it requires one tent of the less dense floats on the molten metal that is denser and are tapped amount needed to import same capacity. separately through their respective spouts. The current rate of unemployment is mostly because our Tuyeres Zone indigenous companies are in comatose due to non-availability of The blast of oxygen for the combustion of coke from the blower to simple fast wearing machine parts. Therefore, the design and the wind box is delivered directly to the charge through the tuyeres. fabrication of cupola furnace using locally sourced materials and indigenous technology will ameliorate the situation by enabling Combustion Zone metallurgical institutions embark on the casting of simple and This zone extends from the top of the tuyeres to a surface boundary complex spare parts needed to operate our ailing industries. This below which all oxygen of the air blast is consumed by combustion furnace will assist research engineers to further their research of coke. knowledge with a view to improving the quality of products and develop new materials. This kind of research work was embarked The reaction is exothermic and the highest temperatures are upon to design, fabricate and construct a functional copular developed in this zone, which may reach 1600˚C to 1700˚C. furnace for the production of cast iron parts for the metallurgical C + O₂ = CO₂ + Heat industries in sustainable development goals. It is noted that all the materials used for the construction of the furnace are locally Reducing zone sourced and they are readily available in Nigeria. This zone is above the combustion zone up to a height of initial coke bed charge, the carbon dioxide flowing upwards through this References zone reacts with hot coke and the reaction is endothermic. 1. Edward K (2008) Cupola Furnace - A Practical Treatise on the CO₂ + C (Coke) = 2CO - Heat Construction and Management of Foundry Cupolas. Because of this reaction, the temperature in the reducing zone is Philadelphia PA: Baird 95 - 250 o reduced to about 1200 C. However, due to the reducing atmosphere, 2. Chastain DS (2000) Iron melting cupola furnaces for the small this zone protects the metal charge above from being oxidized. foundry. Jacksonville FL 86. 3. Gupta OP (2011) Elements of fuels, furnaces and Refractories. Melting Zone Khanna Publishers. This zone includes the first layer of iron above the initial coke bed, the charge starts melting and trickling down to the bottom of the 4. Kirk E (1999) Cupola management. Cupola Furnace - A cupola (well). Practical Treatise on the Construction. 5. Larsen ED, Clark DE, Smartt HB, Kevin LM (2005) Intelligent Preheating Zone Control of Cupola Melting. Transactions of the American This zone includes all the layers of cupola charges above the Foundrymen’s Society 95: 215-219. melting zone to the top of the last charge. In this zone, moisture 6. Lipnitsky A (1978) Melting of cast iron and non-ferrous and volatile matters are evaporated and the outgoing gases heat the alloys. Peace Publisher 56. J App Mat Sci & Engg Res, 2020 www.opastonline.com Volume 4 | Issue 4 | 140 7. Nwajagu CO, CE Ilochonwu (2015) Understanding the 9. Stewart M (1996) Building small cupola furnaces. Selbstverl Technology of Cupola Operation and Management Using 1-100. Local Fabricated Cupola. NMS 13. 10. Ugwu HU, Ogbonnaya EA (2014) Design and testing of a 8. Steven C (2000) Iron Melting Cupola Furnaces for the Small cupola furnace for Michael Okpara University of Agriculture, Foundry. Engineering & Transportation 100-149. Umudike. Nigerian Journal of Technology 32: 22-29.

Copyright: ©2020 Ocheri C. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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