Indian iron was famous in ancient times and it was exported to many countriesthroughout the world Though isolated pockets of iron making existed practically all over the country, yet there was no attempt of systematization and wider propagation. Recently an attempt has been made to establish proto-type furnace and scale it up with modifications in its design.The effect of scale -up.design and process parameters on the productivity of ancient iron making process and recovery of iron in the product has been discussed

Gupta, R N

Roy, B N

Singh, C B

Vaish, A K

English

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191Journal of Metallurgy and Materials Science, Vol. 58, No. 4, October-December 2016, pp. 191-199Printed in India, © NML, ISSN 0972-4257Effect of scale-up, design and process parameters on the productivity of ancient iron making process and recovery of iron in the product1 2 3C. B. SINGH*, R. N. GUPTA , A. K. VAISH  and B. N. ROYO.P. Jindal Institute of Technology, Raigarh - 496 109, India1RVS, CET, Jamshedpur - 831007, India2The M.S. University of Baroda, Vadodara - 390 001, India3Metallurgical Engg. Deptt., BIT, Sindri, Dhanbad - 828 123, IndiaAbstract : throughout the world Though isolated pockets of iron making existed practically all over the country, yet there was no attempt of systematization and wider propagation. Recently an attempt has been made to establish proto-type furnace and scale it up with modifications in its design.The effect of scale -up.design and process parameters on the productivity of ancient iron making process  and recovery of iron in the product has been discussed.Keywords : Ancient iron, Proto-type, Scaled-up, Heat recovery, Productivity, Recovery of iron, Process parameters.INTRODUCTION[1]Iron has been produced and used in India over 3000 years . The technology of iron making has been handed over from one person to another within a limited group.Indian tribals and artisans produced quality iron prtoducts earlier than the developed countries, making use of [2] [3] [4]local iron ores and wood charcoal. the travel records of Voysey , Buchman , Hadfield  [5] [6]and Varier  and a paper of Prof. Turner  clearly shows the supremacy of Indian iron and [7]steel technology even in 18th century. Vaish et al.  have recently discussed the development of ancient iron making technology. The primitive iron making furnace used in age old process was about 80 cm. in height and built of ordinary clay with concave bottom. It comprised of a clay pipe as tuyere through a parabolic opening in the bottom of the furnace. Foot operated bellows were used for air blast. The fluid slag (2FeO.SiO ) was removed 2intermittently through slag hole. After about 4 hour operation the lump of sponge iron luted with slag was removed  with the help of tongs, A lot of entrapped slag was liquefied and forced out during heating and hammering. This clean mass of iron comprised of about 0.08-0.15%C, 0.02-0.05% Si, 0.02-0.03%S, 0.02-0.04% P and 0.001-0.006% Mn apart from about 3 to 7% slag as inclusions. It was extremely ductile and used for making a varieties of implements and decorative articles. The drawbacks with age old technology of iron making were critically reviewed and the design of the furnace was modified. The  furnace was scaled - up  accordingly in order  to make the process more efficient, eco-friendly and economically  viable  for tribal artisans. The proto-type furnace (Bastar model) has been scaled-up to almost five  times  by increasing the height and diameter of furnace thereby increasing the productivity of the process and the recovery of iron in the product. The scaled-up  process has enough scope for commercialization since the articles made out of its product have very good export potential.Indian iron was famous in ancient times and it was exported to many countries *Corresponding Authors Email : cbsingh@opjit.edu.in192 J. MET. MATER SC., Vol. 58, No. 4, 2016C. B. SINGH, R. N. GUPTA, A. K. VAISH and B. N. ROYSCALE-UP AND DESIGN OF PROTO-TYPE FURNACEInitially the operation of primitive furnace for ancient iron making was studied in detail before establishing a proto-type furnace (Bastar model). The proto-type furnace was further scaled-up by (i) increasing the diameter of furnace at its neck region (d) as well as at the bottom of the hearth region (D) and (ii) increasing the shaft height of the furnace (H). The scale -up and design criteria were d/D ratio, H/D/2 ratio, shaft height(H),stack angle (θ) and volume of furnace (V) as shown  in Table 1.The design of the tuyere and its location and type of the air blowing system and its design are to be suitably optimized  so as to increase the productivity of the process. The proto type furnace(Bastar model) in operation is illustrated in Fig. 1, whereas the scaled-up furnace without and with heat recovery system are illustrated in Figs. 2 and 3 respectively.Table 1 : Design parameters of proto-type furnace and scaled-up furnace without and with heat recovery systemSl. No. Furnace Diameter Diameter Height of d : H/D/2 Stack Furnace No. of Temp. Exit gasNo. Type of cross of of furnace D ratio ratio angle θvolume tuyers of air flame3furnace section furnace furnace shaft (degrees) V (m ) blast Temp.O Oat the at the H (cm) ( C) ( C)neck bottomregion of hearthd (cm) regionD (cm)1 Proto- Circular 16 28 80 0.57 5.71 85 0.0309 One Ambient 600-650type Temp.(Bastar 25-35model)2 Scale-up Circular 28 48 127 0.58 5.29 84 0.14671 One Ambient 500-550without Temp.heat  25-35recoverysystem(BastarModel)3 Scale-up Circular 28 48 127 0.58 5.29 84 0.14671 Three 125 450-500with heatrecoverysystem(BastarModel)Fig. 1: A glimpse of proto- type furnace (Bastar model) in operation J. MET. MATER SC., Vol. 58, No. 4, 2016 193EFFECT OF SCALE-UP, DESIGN AND PROCESS PARAMETERS ON THE PRODUCTIVITY...Fig. 2 : Scaled-up furnace (Bastar  model) without heat recovery system in operation.Fig. 3 : Scaled-up furnace  (Bastar  model) with heat recovery system in operation.194 J. MET. MATER SC., Vol. 58, No. , 20164C. B. SINGH, R. N. GUPTA, A. K. VAISH and B. N. ROYPROCESS PARAMETERSThe charge mix  comprises of self fluxing iron ore and wood charcoal. The size of these raw materials ,their chemical analysis and mineralogy play specific role in the operation of iron making. The process of iron ore reduction and its smelting largely depends on (i) rate and continuity of air flow (ii) temperature in preheating, reduction and tuyere zone (iii) CO/CO  2ratio (iv) size and size distribution of ore and reductant (v) ore to reductant ratio in the charge mix and (vi) total residence time in different zones of furnace.EXPERIMENTALCharge materials– The iron ore and Sal charcoal used in proto-type furnace is shown in Fig. 4 and their chemical analyses are given in Table 2 and Table3 respectively.– The chemical analyses of two grades of Bastar iron ore and three types of wood charcoal used in proto-type furnace and scaled-up furnaces are given in Table 4 and Table 5 respectively.Fig. 4 : Bastar iron ore and Sal charcoalTable 2 : Chemical analysis of iron ore from BastarConstituents Bastar OreFe (T) % 60.19SiO  % 1.982Al O  % 12.092 3MnO % NfS % 0.005P % NfJ. MET. MATER SC., Vol. 58, No. 4, 2016 195EFFECT OF SCALE-UP, DESIGN AND PROCESS PARAMETERS ON THE PRODUCTIVITY...Table 3 : Chemical analysis of Sal charcoalSample Particulars : Sal wood charcoal(Air-dried basis) Proximate Analysis :Moisture (M) % 5.6Ash % 1.8Volatile Matter (V.M.) % 20.7Fixed Carbon (FC) % 71.9Ultimate Analysis:Moisture % 5.60Ash% 1.80Carbon % 79.40Hydrogen (cfm)% 2.69Sulphur% 0.03Nitrogen% 0.20Oxygen (By diff)% 10.28Total 100.00C. V. (Kcal / kg) 7060Table 4 : Chemical analysis of two grades of Bastar iron oreConstituents (%) Baster Ore I Bastar Ore IIFe (T) 63.13 60.19SiO 1.55 1.982Al O 7.04 12.092 3MnO 0.056 NfS 0.236 0.005P 0.54 NfTable 5 : Proximate analysis and ultimate analysis of wood charcoal of Sal, Eucalyptus and Acacia with their calorific valuesSl. Sample Wt. (Kg.) Size (Air dried basis)No.  Particulars (mm)Wood Charcoal Proximate Analysis Ultimate AnalysisM Ash VM FC C H S N O(%) (%) (%) (%) (%) (%) (%) (%) (%)1. Sal 2.000 3-0 8.4 3.6 6.8 81.2 82.84 1.40 0.04 0.22 3.50 69002. Eucalyptus 2.000 3-0 9.1 4.9 6.6 79.4 80.34 1.36 0.03 0.20 4.07 67203. Acacia 2.000 3-0 9.3 3.3 6.2 81.2 81.85 1.13 0.02 0.24 4.16 7170Proto-type furnace with usual rate of air blastExperiments were conducted for iron making  in proto-type furnace(Bastar model) making use of  Bastar iron ore  and  charcoal prepared from Tamarind, Jamun and Mahua. The effect of different types of charcoal on the productivity of the process and recovery of iron in the product  is shown in Table 6.C.V.(K. cal/kg)196 J. MET. MATER SC., Vol. 58, No. 4, 2016C. B. SINGH, R. N. GUPTA, A. K. VAISH and B. N. ROY Proto-type furnace with increased rate of air blastAfter a number of trials, proto-type furnace was upgraded with increased rate of air blast   using lumps of two grades of Bastar iron ore and three types of wood charcoal namely Sal, Eucalyptus and Acacia. In this case the amounts of input and output materials were more than double than that of proto-type furnace with usual rate of air blast. Of course the duration of heat was increased from four hours to five and a half hours. The effect of different types of charcoal on the productivity of the process and recovery of iron in the product is shown in Table 7. Scaled-up furnace without heat recovery system The height of proto- type furnace (Bastar model) was increased   for increasing the average residence time of reactants and the overall reduction of iron ore to metallic iron. As a result the 0flame temperature of the exit gas from the furnace came down from about 600 to 500 C. Experiments were conducted making use of two grades of Bastar iron ore and three types of wood charcoal namely Sal, Eycalypus and Acacia.The effect of different types of charcoal on the productivity of the process and recovery of iron in the product is shown in Table 8. Scaled-up furnace with heat recovery systemThe volume of Bastar type furnace was increased to almost two times incorporating heat recovery system in order to improve its thermal efficiency apart from increasing the reduction of iron ore to metallic iron. Heat recovery system was designed to make use of the sensible heat 0of exit gases for increasing the temperature of air blast from ambient to 125 C. This hot blast of air was blown into the furnace through three tuyers-fitted 120 degrees apart. As a result the flame temperature of the exit gas from the furnace came down from about 600 to 4500C or even less. Several experiments were conducted making use of two grades of Bastar iron ore and three types of wood charcoal namely Sal, Eycalypus and Acacia. The effect of different types of charcoal on the productivity of the process and recovery of iron in the product is shown in Table 8.DISCUSSIONThe productivity of the process and the recovery of iron in the product are influenced by scale-up, design and process parameters as follows:Effect of different types of charcoal in proto-type furnaceThe productivity of the process is maximum using Mahua charcoal and minimum while using Jamun charcoal. Likewise the recovery of iron in the product is maximum in the case of Mahua charcoal and minimum in the case of Jamun charcoal(Table 6).Table 6 : Effect of different types of wood charcoal on the  productivity and recovery of iron in proto-type furnace with usual rate of air blastSl.            Charge mix Volume of Duration of Wrought Productivity Recovery Blowing of3 3No. Iron ore Charcoal furnace (m ) heat (hrs) iron (kg) (kg/m /hr) of iron in air into(kg) (kg) in product furnace(%) (liters/minute)1 Bastar ore Sal 0.0309 4 1.71 13.834 52.84 230(5kg) (10kg)2 Bastar ore Tamarind 0.0309 4 1.63 13.187 50.37 230(5kg) (10 kg)J. MET. MATER SC., Vol. 58, No. 4, 2016 197EFFECT OF SCALE-UP, DESIGN AND PROCESS PARAMETERS ON THE PRODUCTIVITY...3 Bastar ore Jamun 0.0309 4 1.54 12.459 47.58 230(5kg) (10kg)4 Bastar ore Mahua 0.0309 4 1.83 14.805 56.55 2305kg (10kg)Effect of different types of charcoal in updated proto-type furnaceBoth the productivity of the process and the recovery of iron in the product do not differ much with different types of charcoal in updated proto-type furnace. These are maximum using Acacia charcoal and minimum while using Sal charcoal(Table 7).Table 7 : Effect of different types of wood charcoal on the productivity  and recovery of iron in proto-type furnace with increased rate of air blastSl.            Charge mix Volume of Duration of Wrought Productivity Recovery Blowing of3 3No. Iron ore Charcoal furnace (m ) heat (hrs) iron (kg) (kg/m /hr) of iron in air into(kg) (kg) in product furnace(%) (liters/minute)1 Bastar ore Sal 0.0309 5.5 3.9 22.947 52.22 280I (11kg) (22kg)2 Bastar ore Sal 0.0309 5.5 3.7 21.771 51.97 280II (11kg) (22kg)3 Bastar ore Eycalyptus 0.0309 5.5 4.0 23.530 53.56 280I (11kg) (22kg)4 Bastar ore Eucalyptus 0.0309 5.5 3.85 22.650 54.07 280II (11kg) (22kg)5 Bastar ore Acacia 0.0309 5.5 4.15 24.410 55.57 280I (11kg) (22kg)6 Bastar ore Acacia 0.0309 5.5 3.90 22.940 54.78 280II (11kg) (22kg)Effect of increased rate of air blast in updated proto-type furnaceAs a result of the increased rate of air blast from 230 liters/minute in proto type furnace to 280 liters/minute in updated proto-type furnace, the productivity of the process increased to almost one and a half times than that in usual proto-type furnace. However, the recovery of iron in the product is almost similar  in both the cases (Tables 6 and 7).Effect of scaled-up parameters– As a result of scale-up,the productivity of the process increased significantly to almost one and a half times in scaled-up furnaces than that in usual proto-type furnace using Sal charcoal. Likewise the recovery of iron in the product is somewhat more in scaled -up furnaces than that in usual proto-type furnace using Sal charcoal (Tables 6 and 8).– While comparing the performance in upgraded proto-type furnace and scaled -up furnaces, the productivity of the process using two grades of Bastar iron ore and three types of charcoal  is almost  similar but the recovery of iron in the product is considerably more in scaled -up furnaces than that in upgraded proto-type furnace (Tables 7 and 8).C. B. SINGH, R. N. GUPTA, A. K. VAISH and B. N. ROY198 J. MET. MATER SC., Vol. 58, No. 4, 2016Table 8 : Effect of different types of wood charcoal on the productivity and recovery of iron in scaled-up furnaces without  as well as with heat recovery systemSl.           Charge mix Volume Duration      Wrought iron             Productivity             Recovery of3No. of of heat                (kg)                 (kg/m /hr)          iron in product (%)Iron ore Charcoal furnace (hrs) Scaled- Scaled- Scaled- Scaled- Scaled- Scaled-3(kg) (kg) (m ) up up up up up upfurnace furnace furnace furnace furnace furnacewithout with without with without with(hrs) (hrs) (hrs) (hrs) (hrs) (hrs)1 Bastar Sal 0.14671 4.5 12.83 13.93 19.433 21.099 51.37 57.00re I (72kg)(36 kg)2 Bastar Sal 0.14671 4.5 13.40 14.30 20.29 21.66 57.88 63.120re II (70kg)(35kg)3 Bastar Eycalyptus 0.14671 4.5 11.85 13.25 17.94 20.06 56.93 65.060re I (60kg)(30kg)4 Bastar Eycalyptus 0.14671 4.5 13.15 15.80 19.91 24.84 56.80 69.750re II (70kg)(35kg)5 Bastar Acacia 0.14671 4.5 11.20 12.65 16.96 19.16 53.81 67.020re I (60kg)(30kg)6 Bastar Acacia 0.14671 4.5 14.10 15.85 21.35 24.00 60.86 69.970re II (70kg)(35kg)Effect of design parameters in scaled up furnacesWhile comparing the performance of scaled-up furnaces without heat recovery system and with heat recovery system along with three tuyers fitted 1200 apart  using hot blast of air ,the productivity of the process is considerably more in scaled-up furnace with heat recovery system as can be clearly seen in Table 8. Thus the changes made in the design of scaled-up furnace by incorporating heat recovery system with hot blast of air using three tuyeres120 degrees apart show positive effect by increasing the productivity of process as well as recovery of iron in the product.CONCLUSIONS– The conventional costly Sal wood charcoal successfully replaced the charcoal made from Eucalyptus and Acacia which grow fast and are comparatively cheaper.– The productivity of conventional furnace of ancient iron making can be increased significantly by substantial enhancement in the blast of air updating its performance.– The scaled-up furnace alone has much higher productivity and increased iron content in its product .– The scaled-up furnace with improved design of air blast system as well as heat recovery system has significant increase in the productivity of the process and the recovery of iron in the product.– The scaled-up furnace with improved design can prove more economical for tribal artisans of our country.EFFECT OF SCALE-UP, DESIGN AND PROCESS PARAMETERS ON THE PRODUCTIVITY...J. MET. MATER SC., Vol. 58, No. 4, 2016 199REFERENCES[1] Vaish A.K. et al., (2000), Historical Perspective of Iron in Ancient India, Journal of Metallurgy and Material Science, 42(1), pp. 65-74.[2] Voysey H.W., (1832), Journal A.S. Society, Bengal, 1, pp. 245.[3] Buchman F.A., (1807), Journey from Madras through the countries of Mysore, Canara and Malabar, London.[4] Hadfield R., (1912), Sinhalese Iron and Steel of Ancient Origin, JISI, 85, pp. 34.[5] Verier E., (1942), The Agaria, H.M. Oxford Press, Calcutta.[6] Turner T., (1894), JISI, XLIV(1893), 162, pp. 179.[7] Vaish A.K. et al., (2007), Development of Ancient Iron Making Technology for Commercialization, I.I.M. Metal News, 10(8), pp. 28-30.

Effect of scale-up, design and process parameters on

the productivity of ancient iron making process and

recovery of iron in the product

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Effect of scale-up, design and process parameters on the productivity of ancient iron making process and recovery of iron in the product

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