China Nonferrous Metallurgy

To solve the technical problems of conventional copper hydrometallurgy such as high acidity of pressure leaching solution, large amount of residue and big loss of copper in downstream neutralization operations, a deacidification technology of copper sulfide concentrate pressure leaching, which is clean, environmental friendly, and easy to operate in industry, is proposed herein based on the acid production mechanism in the process. Findings from associated tests are as follows: a circulation section of pressure leaching solution returning to the previous process can be added in the original production system to reduce the circulation amount of spent electrolyte, decreasing acid from source, subsequent limestone dosage and the loss of copper into the neutralization residue; an efficient leaching of copper from copper sulfide concentrate can be realized under medium temperature and pressure conditions, which also retard the oxidation of elemental sulfur. With appropriate dosage of surfactant, calcium lignosulphonate, the phenomenon of sulfur wrapping copper minerals can be mitigated, improving the leaching efficiency of copper; under appropriately controlled leaching conditions, when the return rate of pressure leaching solution ranges between 40%-50%, copper leaching rate can reach more than 98.5%, the final acid of leaching solution can be reduced to 30g/L and Cu in neutralization residue can drop to less than 1.5%.