Y. RAMA MURTHY, B. CHENNA RAO, GAJANAN KAPURE and VILAS TATHAVADKAR Proceedings of the XI International Seminar on Mineral Processing Technology (MPT-2010) Editors: R. Singh, A. Das, P.K. Banerjee, K.K. Bhattacharyya and N.G. Goswami © NML Jamshedpur, pp. 158–165 NEW PROSPECTIVE FOR THE UTILISATION OF INDIAN LATERITIC CHROMITE OVERBURDEN Y. Rama Murthy, B. Chenna Rao, Gajanan Kapure and Vilas Tathavadkar Iron and Ferro Alloys Research Group R&D Division, Tata Steel Ltd., India, Jamshedpur - 831007, India ABSTRACT Nickel laterites form ~75% of known nickel resources whereas majority of nickel is produced from sulphide sources. Nickel bearing laterite and chromitiferous overburden are the only source of nickel available in India. In India, 5,000,000T of such overburden is generated each year in addition to the 140,000,000T that has already been accumulated over several years of mining and it is estimated to increase with the consumption of chrome ore. With the depletion of sulphide deposits and for the future supply of nickel, the industry must develop for the utilization of laterite ore bodies, especially limonite deposits. In this study, the recovery of nickel associated within the goethite was attempted by employing combination of physical and pyro-metallurgical route from the lateritic ore received from Sukinda region of India. The rejects of the beneficiation process contains chromite which can be used as a feed for the ferro chrome plants. Through physical beneficiation the iron enrichment achieved was 52.74% with a weight percent recovery of 59.67% having Ni-0.9% from the feed assaying 46.73% Fe (T), 0.76% Ni. This beneficiated overburden was used as a feed for the production of pig iron nuggets. Composite pellets of overburden containing lime and coal were reduced at 1400°C for the production alloy pig iron nuggets. The nuggets produced from this route contain C~ 3%, Ni~1.7%, Cr~1.5% and Fe-Rest. Recoveries of iron, chromium and nickel are >95%, >95% and ~30%, respectively. Keywords: Lateritic ore, Nickel, Chromite overburden, Processing, Composite pellets, Nuggets. INTRODUCTION Lateritic nickel ores formed by intensive tropical weathering of ultramafic rocks above all serpentinites which consist largely of the magnesium silicate serpentine and contains approximately 0.3–0.7% nickel. This nickel content is strongly enriched in the course of lateralization. Lateritic nickel ores can be distinguished as limonitic type and silicate type. Lateritization of ultramafic igneous rocks (serpentinite, dunite, or peridotite containing about 0.2–0.3 percent nickel) often results in a considerable nickel concentration. Nickel laterites typically occur in regions where prolonged weathering of ultramafic rocks (containing ferromagnesian minerals) has occurred, favoured by warm conditions with abundant rainfall. The main mineral constituents of the ore are: [1] − Iron minerals: hematite and goethite − Magnesium silicates: serpentine and chlorite − Silicates: quartz − Clay minerals: illite and kaolinite − Spinels: chromite and occasionally some magnetite. 158