Arsenic Reduction and Cobalt Removal in the Arsenic-Containing Leachate from Alkali Leaching of Arsenic-Containing Cobalt/Nickel Residue

摘要

The arsenic and zinc could be leached from cobalt/nickel residue containing arsenic in an alkali medium with air as an oxidant under normal pressure conditions. The leachate contained arsenic and zinc. The arsenic should be reduced for removing cobalt from the zinc sulfate. The results showed that the optimal conditions were listed as follows: temperature of 60 °C, reaction time of 2.5 h, mass ratio of reducing agent to arsenic of 6, the stirring speed of 200 r/min. Under these optimal conditions, the removal ratio of cobalt was over 97%, much more than that without reduction. Then the solution contained less than 0.8 mg/L of cobalt, meeting the standard of zinc industrial production. Arsenic of the leaching solution was effectively recycled for the technology of the arsenic-salt-removal-cobalt-process, reducing the toxic effect of arsenic. It reduced the capital investment of cobalt removal. The method of arsenic recycle effectively decreased the loss of the main metal zinc during the process.