Rate of reduction of chromium ore by liquid iron containing carbon and silicon

The rate of smelting reduction of top-added chromium ore with fluxes such as SiO2, CaO-SiO2 and Na2B4O7 by liquid iron containing carbon and silicon was measured at 1400-1600 degrees C under an argon atmosphere. Experiments were carried out to examine effects of initial silicon content, temperature, kind of fur additive and amount of flux addition. The rate of reduction increased remarkably with an increase of silicon content in liquid iron. It also increased with the addition of various fluxes. Na2B4O7 was found to have the largest promoting effect on the reduction. When fluxes were added it was observed that they reacted with chromium ore to form liquid slag. Therefore, it was estimated that the reduction took place mainly at the interface between slag and metal. The initial rate of reduction is nor affected by the amount of fluxes addition. However, the chromium yield increased with increased amount of fluxes. The effect of temperature on the rate of reduction was significant. The apparent activation energies were about 217 similar to 320 kJ/mol in the case of formation of liquid slag. The reduction mechanism and the rate-controling steps were discussed, finally.