Recycling of cyanide leaching gold wastewater containing iron

For comprehensive recycling of cyanide wastewater, ion exchange resin method is considered as one of the most promising technologies. But for cyanide wastewater with iron of leaching gold, the resin deactivation problem resulting from the presence of iron ions would occur with direct application of this method. Mainly aiming at one gold smelter wastewater containing high copper and high iron cyanides, a new combining process of treating the wastewater was researched, which contained two-step precipitation with ZnSO4 and NaOH combined with A-21S resin adsorption. The results showed that the removal rate of iron ions could reach 100%, CNT- and Cu ion precipitation rate could reach more than 85%, when suitable amount of ZnSO4 was added to the iron cyanide wastewater. The precipitations were mainly Zn2[Fe(CN)6], Zn(CN)2 and ZnCu2(CN)4. And then adding suitable amount of NaOH to the filtrate after separation could make Cu and Zn ion precipitate quickly and the removal rates could reach 37.08% and 70.90%, respectively. The recovery rate of Au ion in wastewater was more than 96% by A-21S resin adsorbing the final separation filtrate under the following conditions: the liquid-solid ratio (volume ratio of filtrate to resin) of 100:3 and stirring for 75 min at room temperature. Using this recycling process, the ion contents of CNT-, Fe, Cu, Zn, Au in the final filtrate were decreased by 94.54%, 100%, 96.34%, 99.87%, 96.76%, respectively, compared with those in the raw wastewater. The final solution could be recycled to the cyanide gold leaching system. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.