At present, arsenic content in copper concentrates is increasing, which leads to an increase in its content in all smelting products, the largest amount of arsenic is transferred in fine dust (dust composition,%: 10-12 Zn, 11-13 Pb, 8-15 Cu , 12-14 Fe, 5-10 As). Autoclaved leaching of dusts (temperature 160-200 °C, oxygen pressure 0.4-0.8 MPa, molar ratio H2SO4 /(Cu + Zn) = 0.75-2.25) to obtain a copper-zinc solution and a cake containing arsenic, iron and lead was studied. Copper extraction in the solution reaches 92%, zinc 95%. Lead, arsenic and iron are concentrated in the cake. Lead from cake is extracted by leaching in sodium chloride solution (temperature 60-70 ° C, NaCl concentration 300 g / dm3). The extraction of lead into the solution is 95%, subsequently lead is precipitated as lead carbonate.
The processing of fine metallurgical dust by pyrometallurgical methods leads to the accumulation of impurities and deterioration in the quality of blister copper. Fine dust contains copper, zinc, lead, arsenic and iron. A hydrometallurgical method for the separation of the main components into the following products is proposed: copper-zinc residue, iron-arsenic residue, lead residue. The hydrometallurgical scheme consists of three stages of leaching: neutral and using sulfuric and nitric acids. When processing metallurgical dust according to the proposed scheme, a solution containing copper, zinc, iron and arsenic is formed, as well as a lead containing precipitate. Arsenic and iron are removed from the solution in the form of iron (III) arsenate, after which zinc and copper are precipitated. Lead in sediment is in carbonated form. The developed technology allows the extraction of: 87% copper, 88% zinc, 83% iron, 83% arsenic, 99% lead in individual products.
Keywords: metallurgical dust, arsenic removal, nitric acid leaching
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