含砷污酸资源化回收铜和砷的新工艺

Novel technique for recovery of copper and arsenic from arsenic-containing waste acid

以含砷污酸为原料,通过中和除杂—沉砷—洗涤—浸出—蒸发结晶—溶解制取三氧化二砷,实现含砷污酸的资源化。结果表明:将污酸中和至pH为2,使污酸的酸度降低;在中和液中加入硫酸铜,控制Cu和As的摩尔比为1.5:1,调节体系pH为8沉淀As,得到亚砷酸铜,As的沉淀率达到97.81%;通过洗涤除杂提高亚砷酸铜中As和Cu的含量;采用10%硫酸溶液,在液固比为5:1条件下浸出亚砷酸铜,所得溶液蒸发结晶得到三氧化二砷与硫酸铜的混合物;用水溶解该混合物后过滤得到硫酸铜溶液及符合YS/T-99-1997As2O3-3号产品标准的三氧化二砷。

A novel technique for recovery of copper and arsenic from arsenic-containing waste acid discharged from copper smelter was proposed, and the process was composed of neutralization and purification-precipitation of arsenic-ashing-leaching-evaporative crystallization-dissolution. Arsenic trioxide and cupric sulfate were obtained and resource of waste acid was accomplished. The results show that the acidity of the waste acid decreases and a certain amount of impurities is removed when the pH value of the system is neutralized to 2 by lime milk. Copper arsenite precipitates with arsenic precipitation efficiency of 97.81% when cupric sulfate is added into the neutralized solution. At the same time, the molar ratio of Cu and As is controlled at 1.5：1 and pH value of system is adjusted to 8 by sodium hydroxide. The contents of copper and arsenic in the precipitate of copper arsenite are increased by washing. 10% sulfuric acid was adopted to treat copper arsenite by leaching at liquid-solid ratio of 5：1, and then, a mixture of arsenic trioxide and cupric sulfate is obtained after the leachate is evaporated and crystallized. Finally, through dissolution and filtration of the solid mixture, cupric sulfate remains in the residual solution while arsenic trioxide meeting the product standard of YS/T-99-1997As203-3 is collected in the filter cake.