Dissolution Behavior of Chromite Ore in CaO-SiO2 System

Numerous investigations proposed that the dissolution of chromite ore is the rate-controlling step for the smelting reduction of chromite ore. The mechanism of chromite ore dissolution in the binary CaO-SiO₂ system is presented. The effect of basicity, temperature, and reducing conditions on chromite ore dissolution is elaborated. The solubility of chromite ore increases considerably when the basicity increases from 0.56 to 0.65. However, the solubility of chromite ore decreases when the basicity further increases from 0.65 to 0.74. The positive effect of reducing conditions on the solubility of chromite ore is evident. The maximum dissolved Cr₂O₃ in slag under reducing conditions by using a graphite crucible reaches 2.6 wt% after 15 min of dissolution. The element diffusion behavior at the chromite/slag interface is elaborated through SEM-EDS technology. The analysis suggests that the rate-controlling step in the early stage is the interface dissolution reaction. After a certain time, the rate-controlling step becomes the mass transfer of Cr₂O₃ from the chromite ore to the chromite/slag interface. The activation energy of the dissolution reaction is $E_{\mathrm{r}}$ = 285.29 kJ mol⁻¹.