Vast jarosite residue was produced from traditional zinc hydrometallurgy process and most of the residue was stored up. According to rough calculation, no less than one million tons of this kind of residue was stored up in China per year. This residue not only takes massive land, but also comes forth great risk of environmental pollution, as it contains significant zinc and lead, as well as some arsenic, cadmium, and such toxic ingredients have the potent of being solved in rain water, as demonstrated. Pyrometallurgical and hydrometallurgical processes are employed for treating such jarosite residue which having some shortcomings such as high fixed investment, high operation cost and the air pollution during fuming.

A clean hydrometallurgical route to recover zinc, silver, lead, copper, cadmium and iron from hazardous jarosite residues producedduring zinc hydrometallurgywas demonstratedby researchers from Institute of Process Engineering, Chinese Academy of Sciences. Using NH4Cl solution as a leaching medium, they dissolved the valuable metals presented in the residue and obtained a kind of residue mainly containing Fe.

The leaching extraction of valuable metals in the NH4Cl medium from sintered jarosite were higher than 95% under the optimal case, while Fe remained in the residues. Then alkali leaching can release most of As from the residue, which detoxified the residue completely. The final residue was almost completely detoxified, and contains about 55 wt% Fe, which can be used as an iron concentration.

The work presented an efficient clean hydrometallurgical progress for treating the hazardous jarosite residue from zinc hydrometallurgy. The progress not only detoxifies the residue, but also recovers the contained valuable metal components. The results were published on Journal of Hazardous Materials, 2011, 192: 554-558.

Article link: http://www.sciencedirect.com/science/article/pii/S0304389411006881

Corresponding author: ZHANG Yifei

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E-mail address: yfzhang@home.ipe.ac.cn