Recovery of metals from the roasted lead-zinc tailings by magnetizing roasting followed by magnetic separation

Abstract

To comprehensively reuse lead-zinc tailings and avoid environmental pollution, the enrichment of valuable metals and the recovery of iron from the roasted lead-zinc tailings (RM), the cinder after the oxidation roasting of lead-zinc tailings, were performed using magnetizing roasting followed by magnetic separation. The transformation of iron in the RM during the magnetizing roasting was investigated by studying the effects of roasting temperature and ratio of coal to RM on the iron recovery. The results showed that most of iron in the RM was transformed from Fe2O3 to Fe3O4 at the roasting temperature of 720 °C and the ratio of coal to RM of 7:100. The iron recovery rate reached 82.16%, and the iron content in the magnetic concentrate reached 62.14%. The investigation of the enrichment characteristics of the metals in the magnetizing showed that Ag, Ga, Pb and Mn could be enriched in the magnetic tailing, with enrichment ratios of 1.64, 1.39, 1.35 and 1.24, respectively, under the conditions of a roasting temperature of 720 °C and a ratio of coal to RM of 7:100. Furthermore, the transformation of metals during magnetizing roasting was investigated by analyzing the microstructure and mineralogical changes during the magnetizing roasting process. With this method, the processes of iron recovery and other metals enrichment from RM using magnetizing roasting followed by magnetic separation was proposed for the comprehensive utilization of lead-zinc tailings.