The effect of pellet technology on direct reduction of jarosite residues from zinc hydrometallurgy

In this study, the coal-based direct reduction technique has been applied to recover the valuable metals lead, zinc and ions from powdery and pellet jarosites. The influence of coal dosage of powdery and pellet jarosite separately on the volatilization rates of lead and zinc and on the metallization rate of iron was investigated. Results showed that the lead and zinc in both powdery and pellet jarosite could be effectively reduced with the volatilization rates higher than 95% and 99%, respectively. However, the iron reduction efficiency of pellet jarosite is better than that of powdery jarosite. The concentration of CO and CO2 gas produced in the reduction process of two types of jarosite were detected and compared to investigate the difference of reduction mechanism between powdery and pellet jarosite. The result showed that the utilization of both CO and C during the reduction of pellet jarosite was higher than that of powdery jarosite. The theoretical analysis was carried out by gas analysis and scanning electron microscopy and energy dispersive spectrometer (SEM-EDS).