Investigations on the carbothermic reduction of chromite ores

Experimental studies were carried out on the reducibility of two different chromite ores using different reducing carbonaceous reducing agents in the temperature range 1173 to 1573 K. “Friable lumpy” ores and “hard lumpy” ores were used in the experiments. Petroleum coke, devolatilized coke, (DVC) and graphite were used as reducing agents. It was found that iron was practically completely reduced before the commencement of the reduction of chromium in the ore. The reduction of iron was controlled by diffusion. The activation energy for this process was estimated to be 130 kJ/mole. The reduction of chromium was controlled by either chemical reaction or nucleation. Rate of reduction was highest when raw petroleum coke was used as the reducing agent. The DVC was less effective compared to raw coke, whereas the rate of reduction was lowest when graphite was used as the reducing agent.