Liquid-phase separation of metallized fines of chrome ore

Abstract

The paper presents the results of the experimental study of the effect of solid-phase metallization time on the yield and composition of metal obtained by subsequent liquid-phase separation. Kempirsai chrome ore fines (1...2 mm) fluxed with quartzite were subjected to solid-phase metallization sintering at 1400 °C in mixture with coal and then separated into metal and slag at 1850 °C. It is found that 2 hours of metallization even at relatively low temperature 1400 °C permits to reduce and extract more than 80 % of chromium and 90 % of iron, and the degree of extraction of both metals after 3 hours’ metallization reaches 95 %. The structure of the metal obtained after the liquid-phase separation of reduction products is similar to the structure of carbon ferrochrome. The metal contains carbides (Cr,Fe)23C6 and (Cr, Fe)7C3 and silicides FeSi2 and Cr3Si. Increasing reduction sintering time increases the amount of silicides and iron content in them, while carbides are enriched in chromium. The slag obtained after separation depletes in iron and chromium oxides with increasing sintering time, Fe and Cr average amount decreasing to 0.5 and 2.5 % after 3 hours of sintering.