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

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—washing—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-99-1997As2O3-3 is collected in the filter cake.