Selective Leaching of Copper and the Removal of Arsenic from Enargite Using High-pressure Oxidative Leaching

High arsenic (As) content in copper ores and concentrates poses challenges to the smelting/converting process, particularly the environmental implications of arsenic emissions. As an alternative, high-pressure oxidative leaching (HPOL) of enargite ore was investigated in this study to achieve selective dissolution of copper and separation of arsenic from high arsenic-containing copper ore. The effects of leaching conditions such as the type of leaching medium, leaching temperature, and total pressure, were investigated. Ferric sulfate (Fe2(SO4)3) was used as the leaching medium under optimized leaching conditions (160°C and 1.0 MPa total pressure). The results showed that the dissolution of copper from enargite ore was limited to around 65%, due to the agglomeration and passivation of mineral particles caused by elemental sulfur, as shown by SEM-EDS. However, the addition of NaCl as an additive significantly improved the copper dissolution rate to about 82%, while about 98% of arsenic was removed as scorodite (FeAsO4•2H2O).