Process Optimization and Reaction Mechanism of Removing Copper From an Fe-Rich Pyrite Cinder Using Chlorination Roasting

The aim is to remove copper from a pyrite cinder by optimzing the chlorination roasting process using response surface methodology (RSM) and the reaction mechanism of chlorination roasting based on thermodynamic calculation was discussed. A quadratic model was suggested by RSM to correlate the key parameters, namely, dosage of chlorinating agent, roasting temperature and roasting time to the copper volatilization ratio. The results indicate that the model is well consistent with the experimental data at a correlation coefficient (R2) of 0.95, and the dosage of chlorinating agent and roasting temperature both have significant effects on the copper volatilization ratio. However, a roasting temperature exceeding 1170 °C decreases the volatilization ratio. The optimum condtions for removing copper from the cinder were identified as chlorinating agent dosage at 5%, roasting temperature at 1155.10 °C and roasting time of 10 min; under such a condition, a copper volatilization ratio of 95.16% was achieved from the cinder. Thermodynamic calculation shows that SiO2 in the pellet plays a key role in the chlorine release from calcium chloride, and the chlorine release reactions cannot occur without it.