Recycling of hazardous jarosite residues based on hydrothermal crystal transformation.

Jarosite [MeFe(SO)(OH)] is a typical non-ferrous smelting slag produced in the process of iron removal from hydrometallurgical solution, which contains a large number of valuable and toxic metal elements. Treating the complex and hazardous jarosite residue in an economically and environmentally sound way has always been an urgent problem. A novel one-step hydrothermal treatment method was proposed in this paper for recycling of jarosite residues.

Resource-recycling and energy-saving innovation for iron removal in hydrometallurgy: Crystal transformation of ferric hydroxide precipitates by hydrothermal treatment.

In hydrometallurgy industry, the accumulation of iron removal residues containing heavy metal elements and toxic elements poses great threats to ecological systems. We propose a novel method to prevent the production of hazardous iron removal residues: firstly, neutralization precipitation is used to purify iron ions in solution; after sedimentation of the obtained suspension, only dense underflow is subjected to hydrothermal reaction, in which ferric hydroxide transforms into hematite crystal. Results showed that ferric hydroxide precipitated into a thin sedimentation layer at temperature greater than 60 °C.