Recovery of nickel, copper and cobalt from low-grade Ni–Cu sulfide tailings

Leaching experiments were carried out to identify optimal conditions for the recovery of Ni, Cu and Co from low-grade Ni–Cu sulfide tailings. Mixed nitric–sulphuric acid solutions were found to be capable of leaching these tailings at ambient temperature and atmospheric pressure. Recoveries up to 91.5%, 85.0% and 54.6% for Ni, Cu and Co, respectively, were obtained under laboratory conditions. Effective removal of iron from the leaching mixture was performed by Na-jarosite precipitation and the resulting Ni, Cu and Co were enriched as a mixture of their sulfide precipitates with metal contents of 8%, 7% and 0.24%, respectively. The proposed leaching procedure is operationally simple and economical and may be applicable in the industrial recovery of valuable metals from Ni–Cu sulfide tailings.