Beneficiation of tungsten ores in India: A review

Abstract

Tungsten is a strategic metal for India, and almost the entire requirement is met by imports. Extensive search for tungsten in recent years has led to the discovery of several deposits. However, almost all these are of low grade compared to world resources. Techno-economic exploitation of these deposits depends to a great extent on the development of suitable beneficiation technology within the framework of an ore-to-product integrated approach. This paper presents a review of the current research and development status of beneficiation technology applicable to these deposits. The deposits covered are: (i) Degana, comprising of four distinct types, namely, quartz vein, eluvial, phyllite and granite, (ii) Balda, (iii) Khobna-Kuhi-Agargoan, (iv) Burugubanda-Tapaskonda, (v) Scheelite-bearing gold ores of Kolar and Hutti, and (vi) Madurai. Investigations on these ores have been mainly carried out by BARC, IBM, BRGM (France), NML and RRL (Bhubaneswar). While studies of BARC have been described in detail, those of the other laboratories are briefly discussed. Emphasis has been laid on discussing the industrial flow-sheets recommended during these investigations. The strategy needed for the techno-economic feasibility of beneficiation of low grade tungsten ores are (i) effective pre-concentration at as coarse a size as possible, (ii) emphasis on higher recovery rather than on high grade of the concentrate, (iii) a two-product approach, one of high grade feasible by physical beneficiation methods and the other of low grade, to be upgraded by chemical methods to directly usable products, thus maximizing recovery, and (iv) a maximum utilization concept, aiming to recover all possible byproducts. The flow-sheets developed for the beneficiation of individual deposits are discussed in the light of the above strategy.