Alteration Characteristics Of Ilmenites From South India

D. S. Rao, T. V. Vijayakumar, S. Prabhakar, G. Bhaskar Raju, T.K. Ghosh

Institute Instrumentation Centre,IIT, Roorkee, INDIA.
National Metallurgical laboratory - Madras Centre,CSIR Madras Complex, Taramani Chennai – 600 113, India.

DOI: 10.4236/jmmce.2005.41005                

Abstract

Two different placer samples from the Navaladi and Surungudi area of Teri,Tamilnadu, in southern India, were collected and characterized in terms of their heavy mineral content. Mineralogical analysis on both the samples revealed the presence of high amounts of garnet and ilmenite. The alteration characteristics of ilmenite from these deposits were investigated by optical and electron probe microanalysis. Optical microscopic studies revealed that the alteration of ilmenite was seen to proceed along grain boundaries and/or fractures resulting in an amorphous to crypto- or microcrystalline mass resembling leucoxene. The alteration is in the nascent stage. Mineral chemistry by electron probe micro-analysis revealed the enrichment of TiO₂, MgO, Al₂O₃, Cr₂O₃, SiO₂, V₂O₅ and Na₂O in the altered products and loss of iron oxide and manganese oxide from the ilmenite grains during weathering leading to the formation of leucoxene. Similarly EPMA studies on garnet indicated that it is of the almandine variety. This study reveals that the alteration of ilmenite by weathering leads to unstable phases, with complex elemental distribution patterns. The physico-chemical characteristics of the mineral and, in turn, the down-stream metallurgical processing are affected by such alteration processes. Key words: Placer Ilmenite, Alteration, EPMA, Navaladi

Keywords

Placer Ilmenite, Alteration, EPMA, Navaladi, Teri

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Mookherjee, A. (1999) Ore genesis: A holistic approach. Allied publishers, New Delhi.
[2]	Suresh Babu, D.S., Thomas, K.A., Mohan Das, P.N. and Damodaran, A.D. (1994) Alteration of ilmenite in the Manavalakurichi deposit, India. Clays and Clay Minerals, 42, pp.567-571.
[3]	Suresh Babu, D. S., Das, D., Sudarsan, M., Reddy, V.R., Chintalapudi, S.N. and Majumdar, C.K. (1996) 57Fe Mossbauer studies on natural ilmenites. Ind. Jour. of Pure and Applied Physics, 34, pp.474-479.
[4]	Suresh Babu, D.S. and Mohan Das, P.N. (1999) Mineralo-chemical assessment of ilmenites from the three Indian placers. Trans. Indian Inst. Met., 52, pp.73-79.
[5]	Rao, D.S., Murthy, G.V.S., Rao, K.V. Das, D. and Chintalapudi, S.N. (2002) Alteration characteristics of beach placer ilmenite from the Chatrapur coast, Orissa, India. Jour. Applied Geochemistry, Vol.4, No.1, pp.47-59.
[6]	Bailey, S.W., Cameron, E.N., Spedden, H.R. and Weege, R.J. (1956) The alteration of ilmenite in beach sands. Econ. Geol., 51, pp.263-279.
[7]	Temple, A.K. (1966) Alteration of ilmenite. Econ. Geol., 61, pp.695-714.
[8]	Wort, M. J. and Jones, M.P. (1980) X-ray diffraction and magnetic studies of altered ilmenite and pseudorutile. Mineral. Mag., 43, pp.659-663.
[9]	Mitra, S., Ahmed, S.S. and Moon, H.S. (1992) Mineralogy and chemistry of the opaque of Cox's Bazar (Bangladesh) beach sands and the oxygen fugacity of their provenance. Sedimentary Geol., 77, pp.235-247.
[10]	Frost, M.T., Grey, I.E., Harrowfield, I.R. and Mason, K. (1983) The dependence of alumina and silica contents on the extent of the alteration of weathered ilmenites from Western Australia. Mineral. Mag., 47, pp.201-208.
[11]	Hugo, V. E. and Cornell, D. H. (1991) Altered ilmenites in Holocene dunes from Zululand, South Africa, Petrographic studies for multistage alteration. South Africa Jour. Geol., 94, pp.365-378.
[12]	Ramakrishnan, C., Mani, R. and Suresh Babu, D.S. (1997) Ilmenite from the Chavara deposit, India: a crictical evaluation. Miner. Mag., 61, pp.233-242.
[13]	Chernet, T. (1999a) Applied mineralogical studies of the Koivusaarenneva ilmenite deposit, Kalvia, Western Finland, with special reference on the altered part of the ore. Chronique De La Rescherche Miniere, 535, pp.19-28.
[14]	Chandrasekharan, S. and Murugan, C. (2001) Heavy minerals in the beach and the coastal red sand (Teris) of Tamilnadu. Exploration and Research for Atomic Minerals, 13, pp.87-109.
[15]	Ramdhor, P.F. (1969) The ore minerals and their intergrowth. Pergamon press, Oxford London, 1174p.
[16]	Grey, I.E. and Reid, A. F. (1975) The structure of the pseudo-rutile and its role in the alteration of ilmenite. Amer. Mineral., 60, pp.898-906.
[17]	Anand, R.R. and Gilkes, R. J. (1984) Weathering of ilmenite in a lateritic Pallid zone. Clays and Clay Minerals, 32, pp.363-374.
[18]	Dimanche, F. and Bartholome, P. (1976) The alteration of ilmenite in sediments. Minerals Sci. Engg., 8, pp.187-201.
[19]	Haseeb, A.S.M., Hug, M. Z. and Kurny, A.S.W. (1997) Characterization of Bangladesh ilmenite and study of its reduction mechanism by X-ray diffraction. Trans. Instn. Min. Metall., Sec.C, 106, pp.39-43.
[20]	Acharya, B.C. Panigraphy, P.K., Nayak, B.B. and Sahoo, R.K. (1998) Heavy mineral placer deposits of Ekakula beach Gahiramatha, Orissa, India. Resource Geology, V.48, No.2, pp.125-136.
[21]	Ahmed, S., Pal, T. and Mitra, S. (1992) Ilmenite from Cox’s Bazar beach ands, Bangladesh:Their intergrowths. Jour. Geol. Soc. Ind., vol.40, 29-41.
[22]	Wort, M.J. and Jones, M.P. (1981) Magnetic properties of ilmenite detrital altered ilmenite and pseudorutile. Trans. Instn. Min. Metall., Sec. C, 90, C130-137.
[23]	Sinha, H.N. (1979) Solubility of titanium minerals. Int. Conf. Advanced Chem. Metallurgy, 2, pp.1-16.
[24]	Chernet, T. (1999b) Applied mineralogical studies on Australian sand ilmenite concentrate with special reference to its behavior in the sulphate process. Min. Engg., 12, pp.485-495.
[25]	Gupta, S.K., Rajakumar, V. and Grieveson, P. (1988) The influence of weathering on the reduction of ilmenite with carbon. Metal. Trans., 20B, 735-745.