Thermal beneficiation of low grade chrome ore from Enuconda deposits, West Godavari District, Andhra

Abstract

A low grade chrome ore from Enuconda mines of West Godavari District, Andhra Pradesh, which could not be upgraded to meet the specifications for metallurgical grade by conventional physical ore-dressing methods. A table concentrate of the ore containing 40.83% Cr2O3, 22.19% total iron, 16.9% Al2O3, 3.22% SiO2, 7.5% MgO, 1.2% CaO and initial Cr : Fe ratio of 1.23: I was used for the beneficiation tests. It was possible to increase the Cr: Fe ratio of the ore to well above 10:1 with more than 90% chromium recovery by preferential solid state reduction of chrome ore and subsequent removal of reduced iron by acid leaching. The briquettes containing -100 mesh (B.S.S.) ore and -170 mesh (B.S.S) coke were reacted at 1250°C for 2 hours and the reduced ore was leached with dilute sulphuric acid at 100°C. Controlled leaching conditions have also been found to yield a metallurgically suitable beneficiated product with almost full chromium recovery. (Miss Sipra Samanta, Messrs R.N. Misra and P.P. Bhatnagar, National Metallurgical Laboratory)