Beneficiation of Low Grade Chromite Ore and Its Characterization for the Formation of Magnesia-Chromite Refractory by Economically Viable Process

Authors: Amit Kumar Bhandary, Prithviraj Gupta, Siddhartha Mukherjee, Mahua Ghosh Chaudhuri, Rajib Dey

Abstract:

Chromite ores are primarily used for extraction of chromium, which is an expensive metal. For low grade chromite ores (containing less than 40% Cr₂O₃), the chromium extraction is not usually economically viable. India possesses huge quantities of low grade chromite reserves. This deposit can be utilized after proper physical beneficiation. Magnetic separation techniques may be useful after reduction for the beneficiation of low grade chromite ore. The sample collected from the sukinda mines is characterized by XRD which shows predominant phases like maghemite, chromite, silica, magnesia and alumina. The raw ore is crushed and ground to below 75 micrometer size. The microstructure of the ore shows that the chromite grains surrounded by a silicate matrix and porosity observed the exposed side of the chromite ore. However, this ore may be utilized in refractory applications. Chromite ores contain Cr₂O₃, FeO, Al₂O₃ and other oxides like Fe-Cr, Mg-Cr have a high tendency to form spinel compounds, which usually show high refractoriness. Initially, the low grade chromite ore (containing 34.8% Cr₂O₃) was reduced at 1200 ⁰C for 80 minutes with 30% coke fines by weight, before being subjected to magnetic separation. The reduction by coke leads to conversion of higher state of iron oxides converted to lower state of iron oxides. The pre-reduced samples are then characterized by XRD. The magnetically inert mass was then reacted with 20% MgO by weight at 1450 ⁰C for 2 hours. The resultant product was then tested for various refractoriness parameters like apparent porosity, slag resistance etc. The results were satisfactory, indicating that the resultant spinel compounds are suitable for refractory applications for elevated temperature processes.

Keywords: Apparent porosity, beneficiation, low grade chromite, refractory, spinel compounds, slag resistance.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1126131

References:

[1] Pariser Gerhard C., Chromite: World Distribution, “Uses, Supply & Demand, Future”, PDAC Convention, Toronto, March 2013
[2] Nafziger R H, “A review of the deposits and beneficiation of lower-grade Chromite”, Journal of The South African Institute of Miningand Metallurgy, 205-226, August,1982
[3] Rama Murthy Y, Tripathy S K, Raghu Kumar, C., “Chrome ore beneficiation challenges & opportunities – A review”, Minerals Engineering, 24, 375–380, 2011
[4] Tripathy, S K, Singh, V, Ramamurthy, Y, “Improvement in Cr:Fe Ratio of Indian Chromite Ore for Ferro Chrome Production”, International Journal of Mining Engineering and Mineral Processing, 1(3), 101-106, 2012
[5] Kapure, G., Rao, C.B., Tathavadkar, V., Raju, K.S., Process for Effective Utilization of Low Grade Chromite Overburden, The Twelfth International Ferroalloys Congress Sustainable Future, Helsinki, Finland, pp 377-382, June 6 – 9, 2010
[6] Sen R. Physical and chemical characterisation of briquettes made from Indian and South African Chromite concentrates and their smelting behaviours, PhD thesis, Jadavpur University, PhD thesis, Jadavpur University, 2010
[7] Gilchrist J D, Fuels, Furnaces and Refractories, Pergamon Press, 1977
[8] Kiyoshi Goto, “Chromite in Refractories”, Resource Geology, 47(4), 223-229, 1997
[9] McEwan, N. Courtney, T., Parry, R. A. and Knupfer, P, “Chromite—A cost-effective refractory raw material for refractories in various metallurgical applications”, Southern African Pyrometallurgy, March 6–9,2011
[10] C. Biswas, M. Tech thesis “Pre-reduction of iron ore briquette by gasification of lean grade coal”, Jadavpur University, 2012.
[11] M. Saki, A.K. Chakrabarti, W. Kipit: Concentration of Hessen Bay Chromite Ore 7thHuon Seminar achieving vision 2050 through higher education, research, science & technology. November 13th to 14th 2013, Papua New Guinea University of Technology, Lae, Papua New Guinea
[12] Fabiano Magalhães · Márcio César Pereira ·José Domingos Fabris · Sue Ellen Costa Bottrel ·Alejandro Amaya · Nestor Mogliazza ·Rochel Montero Lago, (2010) 195:43–48.
[13] MIS Myanma Ceramic Industrie, "refractories bricks manufacturing plant, quality control Manuals", 2001.
[14] Sarkar, R., Ghosh, A., Das, S.K. Reaction sintered magnesia rich magnesium aluminate spinel: effect of alumina reactivity. Ceramics International, v. 29, n. 4, p. 407-411, 2003
[15] Norton, F.H. "Refractories", 3rd ed., McGraw-Hill book company, New York, 1949.
[16] Shaw K., Refractories and Their Uses, Applied Science Publishers Ltd., London, 1972.
[17] Kingery, W.D., Bowen, H.K., and Uhlmann, D.R., “Introduction to ceramics”. John Wiley and sons, New York, (1976).