Recovery of metals from jarosite of hydrometallurgical nickel production by thermal treatment and leaching

Jarosite is a harmful by-product of hydrometallurgical process and is categorized as hazardous waste due to the presence of heavy metals (Cu, Ni, Pd, etc.) in it. It is difficult to recycle these metals due to their complex phase structures. In this study, a facile and novel process for recovering metal values from jarosite in nickel hydrometallurgical process was developed. The jarosite was firstly thermally treated at a low temperature (650 °C). During this process, the jarosite turned into simple phases, and valuable metals were released in forms of Cu 2+ , Ni 2+ and Fe 2 O 3 . Then, the thermally decomposed product was leached by water. 93.58% copper and 95.78% nickel can be recovered. The iron in the leaching residue can be directly recycled as iron oxide product. The proposed process has advantages in low chemicals consumption and short process. It can not only efficiently recover metal values (Ni, Cu), but also realize high-value utilization of iron resources, which enjoys significant application potential in the comprehensive utilization of jarosite. • The jarosite was decomposed into sulfates and Fe 2 O 3 by thermal treatment. • Cu and Ni in the decomposition product of jarosite was leached by water. • Fe 2 O 3 left in leaching residues was directly recycled as iron oxide product. • The process is short and recovers metal resources in jarosite.