Rare Metals Extraction from Non-ferrous Resources in India: Present Status and Prospects of R&D

Abstract

Rare metals comprise of those naturally occurring elements with relatively lesser abundance in the earth 's crust which are difficult to extract by normal metallurgical processes. The present paper summarizes the ore / mineral resource base including the secondary resources, current usage and extraction technology of rare metals in India. The R&D in India has resulted in the exploitation of such processes or poised for gainful utilization. As the tech-nologies for extraction of rare metals follow a different methodology than those applicable to the normal base metals and were not readily available at the early stage of development during 1950-1990s, indigenous developments matured and were put to use; a few such technologies are described. Mention may be made of the applications of special processing options such as: halide metallurgy, strong acid / alkali treatment for breaking down the refractory minerals FIF/ alkali fusion ; solvent extra-ction/ ion exchange for metal separation, and vacuum melting/ electron beam melting/ refining etc for melting/ refining, to meet the stringent specifications of the rare metals . In most cases, extraction is carried out using primary resources , but for metals not present in a substantial quantity in natural ores or in diffused state, secondary resources are exploited. Secondary resources are particularly criticalfor Ga, V, Mo, W, Se, Te etc. Possi- bilities for further research are indicated to ensure secured supply ofthese metals in future.