Oxidation Sulfuric Acid Autoclave Leaching of Copper Smelting Production Fine Dust

Abstract

Lead, zinc, and arsenic are associated elements in copper ores. Due to deterioration of concentrate quality and involvement in recycling of secondary raw materials, these impurities are increasingly circulated in copper-smelting production, most often collected in fine dusts. Recovery of these dusts for pyrometallurgical processing leads to contamination of black copper with arsenic and lead.

Results are provided for sulfuric acid autoclave leaching of OAO SUMZ dust and dust obtained after recovery melting, containing alongside copper and zinc considerable amounts of lead and arsenic. The effect of temperature and acid concentration on autoclave leaching indices is studied.

Optimum dust leaching parameters are obtained: temperature 160°C, H₂SO₄ /(Pb+Zn+Cu) = 2.1, \( {P}_{{\mathrm{O}}_2}=0.3\mathrm{MPa} \), τ = 2 h, and with these parameters the maximum degree of leaching for arsenic, copper and zinc is observed.

Direct oxidizing sulfuric autoclave leaching of fine dust makes it possible to extract up to 89% copper and 92% zinc. Arsenic passes into a cake in the form of iron arsenate, which complicates subsequent processing. In order to exclude deposition of arsenic during autoclave leaching it is necessary to remove arsenic from dust where it is present in the form of oxidized compounds, and therefore it is possible to use atmospheric sulfuric acid leaching for its extraction. During two stages of atmospheric and autoclave oxidation leaching, it is possible to extract up to 93% Cu, 96% Zn, and 99% As.