The State of Bihar is rather unfortunate to have so many  leaner  and  unmarketable  mineral deposit.  It  is endowed with a wide mineral deposits. It is endowed with a wide mineral resource base (Table-1) and condtinue to be a leading state in mineral production accounting  for  about 25 percent of the total  value  of  minerals  produced  in India. But this fortunate trend is not going to last long

Singh, Akhileshwar

Singh, J P

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Need for utilization of leaner and unmarketable ores of Bihar by innovation in ore dressing and metallurgical process * Akhileshwar Singh and ** J. P. Singh The State of Bihar is rather unfortu-nate to have so many leaner and unmarke-table mineral deposits. It is endowed with a wide mineral resource base (Table-1) and con-tinue to be a leading state in mineral production accounting for about 25 percent of the total value of minerals produced in India. But this fortunate trend is not going to last long. The information available in Table-1 in-dicates that in the last one decade, in case of some important minerals there has been consider-able increase in reserves but the rated rise in production has not kept pace with increase in reserves. This trend of production shows that most of mineral reserves in Bihar including new mineral-finds contain generally leaner and un-marketable ores. Table — 1 	 Relative status of Bihar's mineral resources and their production Ore / Mineral Reserves in million 	 tonnes Production in tonnes 1973 1983 1973 1983 1. Andalusite 4 Nil Nil 2. Apatite 1.0 1.094 4507 Nil 3. Asbestos 0.380 0.403 799 22 4. Barytes 0.11 Nil 57 5. Bauxite 35 115 4,45,520 5,86,223 6. Bentonite 0.1 19 12,700 Nil 7. Chromite 0.28 0.38 745 170 8. China clay 36 382 53,742 41,803 9. Coal 35,230 56,049 33,420 53,753 10. Copper ore 140 216 8,15,017 13,12,183 11. Fireclay 28 314 2,26,344 1,68,695 12. Felspar 2 758 440 13. Graphite 2.25 6.2 648 14,212 14. Hematite 1,137 3,758 4,784 6,900 15. Kyanite Massive 0.2 0.09 44,745 20,100 Low grade 5.57 89 16. Limestone* 860 1,200 3,021 2,177 *Qty in 000 tonnes. * Mineral Development Officer, Govt. of Bihar, Patna ** Geologist, Govt. of Bihar, Patna A large belt of low grade andalusite bearing rocks (1.3 million tonnes) occurs in the western part of Palamu district. The mineral needs beneficiation. The beneficiation studies conducted by N.M.L. and 1B M have demonstrated that low-grade apatite of Singhbhum is amenable to beneficiation. Pilot plant tests done by N.M.L. have yielded rich concentrate. However, the deposit is presently not being exploited. There is need to commercialise and economise the beneficiation procedure and improve its mineability. In Bihar, the reserves of asbestos are small. They are mostly of amphibole variety. Chrysotile asbestos is confined to limited area. There is a modern milling plant only at Moro Mines in Sing hbhum district. At other places fibres are separated by hand sorting, resulting in poor recovery of fibres. There is also need to recover chromite and olivine which are available as associated minerals and have greater demand in the market. Barytes of Singhbhum:  Palamau and Ranchi districts are mostly impure and off-colour. These deposits could not be exploited for want of proper beneficiation. In the last two decades, mainly due to all out efforts of the Department of Mines and Geology;  Bihar, the total reserves of all grade of bauxite in Bihar have although been revised from 40 to 115 million tonnes, the production of bauxite within the state has remained steady over the last five years at around 5.4 Iakh tonnes per year. In the year 1982, out of the total production of 5,68903 tonnes, about 40% consisted of over 50% Al2 03 and the balance of about 45% A1203 . In Bihar, the bauxite mining and process-ing industry is entirely in the hands of private sector. They do not use bauxite containing +40 percent Al2 03 	 Instead of finding utility of high grade bauxite in refractory and abrasive industries, it is being used in cement and alumina industries whereas low grade ore is being dum-ped with waste material. During inspection of bauxite mines in Bihar State, the IBM has obser-ved that generation of such mineral rejects has been estimated to be varying from 25% to 90% of the marketable grade of ore produced. The IN D A L C 0 are planning a high-grade refrac-tory unit based on their captive mines at Bagru near Lohardaga and are also recovering vana-dium pentoxide as sludge from their alumina plant at Muri. The Department of Mines and Geolog, Bihar have taken keen interest in diversification programme of IN D A L C 0. There is need to further simplify and economise beneficiation procedures. Problems of energy conservation with respect to alumina industry also need serious consideration. Perhaps in near future, the "Blast Furnace route "may replace the " Electrolysis route" of alumina smel-ting. In bauxite ore of Bihar, titanium oxide con-tent generally goes up to 12%. There is need to develop a technology for recovery of the scarce raw material from red mud. On account of exploration efforts of the State Department of Mines and Geology, the reserves of bentonite in Bihar have been revised from 0.1 to 19 million tonnes. The raw material is lying mostly unutilised for want of proper beneficiation procedure. It is calcium bentonite of non-swelling type, usually referred to as fuller's earth.The calcium ions present could be re-placed by sodium-ions by adding requisite quan-tity of soda-ash. Conversion can take place during the process of mixing and grinding. This tech-nology should be commercialised for upgrading such bentonite. Samples have been sent to N.M.L. for suggesting a proper technology for the purpose. Hitherto, chromite used in the production of high-carbon ferrochrome, low carbon ferro- 345 chrome, had to be lumpy, with a Cr2 03 content of 48% minimum and Cr/Fe ratio of 2.8:1. This resulted in rejection of three-fifth of the high grade ore produced because of size res-triction. A lot of R&D work has been done to over-come the above problems but so for no satisfactory result has been achieved. In SRC (Semi Reduction Charge) process developed by Showa Denko (Japan) and Outo-kompa process of Finland, ferro-chromite is satisfactorily produced from fines of chromite containing: — as low as 42 to 44 Cr 2 0 3 — Cr/Fe ratio of 1.6:1 The above technological innovations may in-crease the reserves of usable chromite ore of the state. Reserves of china clay available in Bihar are of the order of 382 million tonnes. Nearly 20% of the reserves contain inferior quality of china clay, mainly located in Ranchi district. Inspite of the inherent good qualities of china clay in the state, the production has remained stagnant in last one decade, mainly due to : appreciable variation in chemical and physi-cal characteristics from area to area and also in depth and that no single process of bene-ficiation has been found effective. monopoly of private sector who are shy to undertake beneficiation process. — high cost of processing which perhaps works out to be Rs. 120 to Rs. 200 per tonne. For optimum utilisation of copper ore of Bihar and its bye-products, the suggested R in D work to be undertaken are— acid leaching of oxide ores and bacterial leaching of low grade ores, recovery of bye-products like magnetite. Presently gold, silver, selenium, nickel sul-phate and tellurium are being recovered as by-products (HCL — ICC) and study of mine-water with a view to utilise it for industrial purposes. Against all India coal reserves of 1,22,223 million tonnes, Bihar has a reserve of 56,049 million tonnes although the production of coal and its value-added utilisation is in-adequate. This requires attention in a collective way. There should also be effort to collect by-products. The coal-ash contains titanium oxide to the level of 1.6 to 3.6% and phosphorous 0.6 to 2.6 percent. The technology and the economics need to be worked out. The glass and ceramic industries are the major consumers of felspar and account for 34 percent of total consumption. Felspathic pegma-tites are wide spread in Bihar and the total area under mining lease is of the order of 1994 hectares. The production has declined by 40% in last one decade. The deposits should be thoroughly assessed for their reserves and grade. Intergrowth of other minerals along with felspar in the pegmatite body needs specific study. Such intergrowth constitutes intimate mixture rendering the separation diffucult. And lastly the cost of mining, crushing and grinding gene-rally do not commensurate with prevalent market price of the mineral felspar from econo-mic point of view. There is scope for specific study of cost structure. The beneficiation plant is the basic need for graphite industry. There are presently 4 bene-ficiation plants in Palamau district of Bihar with aggregate capacity of 70,000 tonnes per year. The fifth beneficiation plant of B.S.M.D.C. based on N.M.L. know-how is also likely to be set up shortly. 	 On an average, in the existing plants, the percentage of recovery is only 15% as against 90% arrived by N.M.L. in their experiments. Secondly the cost of processing is Rs. 300 per tonne as against Rs. 106.40 per tonne of selling price of r.o.m. graphite. This gap in experimen-tal and actual practice needs to be narrowed down for proper conservation of graphite re-sources. 346 Two varieties of garnets viz, gem and industrial occur as associated mineral in Hazari-bagh district. For winning both varieties, the technology need to be worked out. This would certainly be a low investment project and would help weaker sections of the region to get quick returns. The total hematite reserves in Bihar, as reassessed by the Department of Mines and Geology, Bihar is of the order of 3758 million tonnes. These are reserves of hematite with —55 iron content. Bihar ore is also relatively more friable. Presently fines generated at the rate of one million tonnes per year are stacked. Thus accumulation of fines has reached more than 20 million tonnes. There is need for a central crushing, washing and screning plant in the region. The reserve of low-grade kyanite in Bihar occuring in qua rtz-kyanite rock is estimated at about 89 million tonnes. So fa r, these reserves have not been exploited for lack of suitable process for recovery of kyanite. The technology of C.G.C.R.I, I.B.M., and N.M.L. for the purpose have not perhaps crossed the experimental stage. Before independence, for manufacture of portland cement by wet-process, the minimum CaO content in limestone was considered at 400, thereby allowing utilisation of marginal grade limestone without beneficiation. After indepen-dence, the cut-off grade of CaO for Mega, Mini and Tiny cement plants is 42,44 and 46 percent respectively. Such upward enhancement of "cut off grade" by the modern technology is detrimental and against the theme of conserva-tion. Most of Bihar limestone are of marginal grade. M/s ACC's plants, located in Singhbhum and Ranchi districts are consuming limestone after flotation treatment. Same is the case with Mls R. I. Ltd. plant at Dehri-on-sone. Therefore, there is need to develop a technology for cement manufacture best suited to Bihar limestone. Conclusively, serious consideration has to be given for utilization of leaner and un-marketable ores of Bihar by innovation in ore-dressing and metallurgical processes. 347 

Need for Utilisation of Leaner and Unmarketable ores of Bihar by Innovation in ore dressing and Metallurgical Process.

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Need for Utilisation of Leaner and Unmarketable ores of Bihar by Innovation in ore dressing and Metallurgical Process.

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