Study On Treating Slag Of Silver Extracted By Hydrometallurgical Process

A new hydrometallurgical process has been proposed to recover Cu and Bi from slag of silver extracted. Firstly, slag was leached by a sulfuric acid solution and the filtrate was used to prepare CuSO₄.5H₂O of the first grade. Next the bismuth was extracted from the leached residue by a mixed solution of HCl-FeCl₃. Bismuth oxychloride and copper concentrate were obtained by neutralizing the filtrate to pH value 2.5 and 6⁷ respectively with Na₂CO₃ solution. At last, high purity bismuth chemical products such as Bi(NO₃)₃.5H₂O, BiONO₃, BiOCO₃.1/2H₂O, and Bi₂O₃ have been prepared from bismuth oxychloride. So the value metals, such as Cu, Bi, and Ag in the slag, have been recovered as CuSO₄.5H₂O or copper concentrate, high purity bismuth chemical products, and silver concentrate, respectively.The process has high recovery rate of value metals and an economic advantage. Total recovery rate of Cu, Bi, and Ag is 98.9%, 96% and 98.7% respectively. Direct recovery rate of Cu and Bi is 91% and 88%, respectively. The CuSO₄.5H₂O quality obtains the standard of the first grade and the Cu content in the copper concentrate is more than 20% and the bismuth content in bismuth oxychloride is more than 60%. Thecontents of metal impurities in the bismuth products obtain the standards of the analysis reagent and the contents of anions obtain the standard of the grade of chemical purity.