Oxidative Leaching Mechanism of Arsenic from Arsenic-containing Cobalt and Nickel Slag in Alkaline Medium

The oxidative leaching mechanism of arsenic in alkaline medium from arsenic-containing cobalt and nickel slag from the purification unit of zinc sulfate solution was studied.The results indicated that the arsenic leaching was closely related to temperature,alkaline concentration and reaction atmosphere.When the leaching was under inert atmosphere,both CuO and Cu2O existing in the original slag could act as the oxidants for arsenic leaching.At the leaching temperature of 80℃ or below,CuO played the main role in the oxidative leaching of arsenic,the highest leaching rate of As was not over 53%,and the reduction product was Cu2O.While at the temperature of 100℃ or above,both CuO and Cu2O could act as the oxidants for the arsenic leaching,the highest leaching rate of As was up to 90%,and the reduction product was Cu.When the leaching was under oxygen atmosphere,the leaching rate was over 98%.Except that the oxygen itself could act as the oxidant to oxidize arsenic directly,the copper in the slag could be the electron carrier between O2 and arsenic in a low valence state,which intensified the oxidation reaction.