7. High-Pressure Leaching Arsenic Containing Polymetallic Copper Mattes

Lead, zinc, and arsenic circulate in the intermediate products of metallurgy enterprises because of the bad quality of the concentrates used and the inclusion of secondary raw materials into the process. These intermediate products are mainly represented by dusts. Recycling of these dusts in smelting aggregates leads to the contamination of blister copper with arsenic and lead. This chapter presents some results of oxidizing sulfuric acid pressure leaching and leaching with copper sulfate solution of mattes obtained from the joint reduction smelting of these dusts. The option of cake treatment after pressure leaching with a copper sulfate solution is shown here. The oxidizing sulfuric acid pressure leaching is carried out in the temperature range of 140–180 °С, acidity range of 10–80 g/dm³, and pressure of 0.4 MPa that allow one to extract 94.2% of copper into the solution. Iron, arsenic, and lead remain in the cake after leaching even after the repeated leaching. This fact makes it difficult to process the cake at the lead enterprises by a conventional technology. The pressure leaching with a copper sulfate solution of mattes is proposed as an alternative to the oxidizing sulfuric acid pressure leaching. This leaching allows one to extract up to 93% of arsenic, zinc, and iron into the solution in the temperature range of 140–180 °С. The cake after pressure leaching with copper sulfate solution may be subjected to the oxidizing sulfuric acid pressure leaching to obtain a lead cake which may be used at lead plants. There is a scheme of processing of mattes including the pressure leaching with a copper sulfate solution as one of the basic operations followed by the oxidizing sulfuric acid pressure leaching.