New pyrometallurgical route for separation and recovery of Fe, Zn, In, Ga and S from jarosite residues

This paper developed a new pyrometallurgical route for separation and recovery of Fe, Zn, In, Ga and S from hazardous jarosite residues based on the understanding of the thermal decomposition and desulfurization of jarosite and its importance to the subsequent separation and recovery of metal elements. The main steps in the proposed process included preliminary roasting of jarosite residue for dehydration and desulfurization, reductive roasting for selective volatilization of Zn and In, and smelting for producing Fe, Ga-bearing alloy and clean slag. To achieve this goal, the residual S content of the jarosite residue in principle should be less than 1.3%, which was usually attainable by pre-roasting at high temperatures of above 1200 °C. In this case, more than 99% Zn and about 85% In were volatilized with reductive roasting of the pre-desulfurized jarosite residue at 1200 °C for 70 min, while more than 93% Fe and 90% Ga were finally recovered in the alloy when smelting the reduced jarosite residue at 1500 °C for 20 min with a slag binary basicity of 0.8. Meanwhile, a clean slag was obtained which were believed to be safe for storage or potentially used as construction materials.