Reducing power consumption in zinc electrowinning

Approximately 7 million tons per annum of zinc are produced globally by traditional electrowinning which is a power intensive process. Power consumption is directly proportional to cell voltage which is thermodynamically limited to the potential difference between the oxygen evolution and zinc reduction reactions. This article summarizes several novel approaches which are currently under investigation/or the reduction of power consumption in zinc electrowinning and which focus on alternative anode reactions. In particular, methanol, formic acid, ferrous to ferric and hydrogen oxidation as anodic reactions are examined. There remain several important materials, engineering, and process challenges associated with the new approaches which are reviewed in this article. However, given the current and anticipated future cost of energy, further research is warranted.