Arsenic Removal from Cu–As-Containing Filter Cakes by Na2CO3 Leaching

Abstract

In the present study, a process for selective removal of arsenic from Cu–As-containing filter cakes using Na₂CO₃ leach was examined. When decreasing the weight percentage of arsenic in Cu–As-containing filter cakes, environmental problems can be eliminated while valuable metals will be recycled. The effect of α(Na₂CO₃) (where α represents excess coefficient), temperature, L/S ratio and leaching time were investigated. the optimal leaching conditions were achieved as follows: α(Na₂CO₃) = 2.7, L/S ratio 6 : 1 (mL/g), temperature 75°C, leaching time 3 h, where the leaching efficiency were 96.47% for As, 0.41% for Cu with final As and Cu concentrations of 11.72 and 0.02 g/L respectively. Further analysis showed that the Cu content in the leach residue increased to 51.42% with CuS as the major Cu phase. Notably, only 0.92% of As remained in the leach residue. The leaching solution was treated by sodium persulfate oxidation and arsenic precipitation which eliminated As 99%, leaving 0.5 mg/L As in the solution. Therefore, the proposed process is a viable method for the effective separation of Cu and As in Cu–As-containing filter cakes. Broadly, the results of this paper provide a reference for the treatment of arsenic sulfide from nonferrous metallurgy cyclic leaching process.