Thermal beneficiation of low-grade chrome ore from Vagda Deposits, Ratnagiri District ,Maharashtra

Abstract

The paper records the research results of thermal beneficiation of low grade chrome ore from Vagda deposits, Ratnagiri district, Maharashtra. The ore could not be upgrade to the desired Ce: Fe ratio, by convectional physical methods of beneficiation, but was successfully beneficiated by preferential reast reduction and acid leaching, to yield a metallurgical grade of the upgrade product. A table concentrate of the ore containing 44.93% Cr2O3, 15.39 % total iron, 14.9% Al2O3, 8.9% MgO, 2.3% SiO2, 1.1% CaO and an initial Ce: Fe ratio of 1.53:1 was reduced with varying quantities of solid reducing agent ,at different temperature and iron leached with dilute sulphuric acid. The Ce:Fe ratio thereby increased to 8:1 with more than 87% chromium recovery by preferential reduction of -72 mesh (B.S.S) size ore with the -170 mesh (B.S.S) size coke, at1250°c for a period of 21/2 hours and subsequent leaching with dilute sulphuric acid. It has been observed that chromium dissolution can be suppressed appreciably by controlled leaching with restricted amount of sulphuric acid, to yield a metallurgically suitable beneficiated chrome ore.