Extraction of non-ferrous metals and arsenic from fine dusts of copper smelter production by combined technology

Abstract

Fine dusts of copper smelting production are a valuable raw material for the extraction of heavy non-ferrous, noble and rare metals. A feature of dusts is the high content of arsenic in them, which must be removed from the production cycle in the form of a product suitable for safe storage. The most rational way is the combined technology for processing copper smelting production dusts including low-temperature dust roasting (calcination) in order to distill arsenic into a separate product and to break up poorly soluble sulfide and ferrite zinc and copper compounds. The chemical and phase composition of Ausmelt technology dusts is presented. Thermodynamic calculations of reactions occurring during the dust roasting were carried out in order to study the behavior of copper, zinc, arsenic and iron compounds when roasted in the temperature range of 20–1000 °C, features of solid phase formation and composition, optimization of arsenic roasting and distillation conditions. It was established that dust calcination allows the conversion of poorly soluble sulfides and ferrites of zinc and copper into acidsoluble oxides and sulfates. Thermodynamic parameters were determined for the sulfuric acid leaching of individual cinder compounds. The results of laboratory studies showed that the calcination temperature of 550 °C provides the most satisfactory results of arsenic conversion to sublimates (more than 95 %) as well as copper and zinc recovery into the solution during sulfuric acid leaching (more than 90 %). The initial acidity of solutions of 50 g/dm3 and solution temperature of 60°C are sufficient to achieve high values of copper and zinc recovery into the solution.