Chrome Ore Mining

Chromite deposits are mined by both underground and surface techniques. Much of the ore is rich enough to be used directly: for production of ferrochromium, a rich, lumpy ore containing more than 46 percent Cr2O3 and having a chromium-iron ratio greater than 2:1 is preferred, but ores with a lower ratio and as little as 40 percent Cr2O3 are also used. (Ores high in alumina are preferred for processing into refractory brick.) As finely divided ores, which do not smelt efficiently, come under greater exploitation, a number of processes are employed to agglomerate them for more satisfactory use in furnaces. Fines can be blended with fluxes and coke (the principal source of carbon) and then preheated or ìprereducedî before being charged into an electric smelting furnace.