Slags and mattes in vanyukov’s process for the extraction of copper

Slags and matte in Vanyukov’s process, an autogeneous method of processing sulfide concentrates of nonferrous metals used in a specially designed furnace at the Balkhash copper-smelting plant (Kazakstan), have been characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The liquid matte was shown to have contained 3.6 wt pct of slag inclusions and about 4 wt pct of magnetite. The solid matte is a mixture of sulfide phases. The liquid-waste slag was shown to have contained 0.6 wt pct of matte inclusions and about 3 wt pct of magnetite. The silicate field of the solid slag consists of two phases, identified as iron orthosilicate and iron metasilicate. It was shown that most slag formation occurred before the emulsion reached the settling tank of the furnace. Thermodynamic calculation of the exchange reactions for the oxide and sulfide components of the slag showed that zinc and lead dissolved in the slag are present mainly as oxides, but with only a small part (10 to 20 pct) in the form of sulfides. By contrast, copper is present in the slag as dissolved sulfides and also as matte reguli. The results of these thermodynamic calculations are supported by the experimental data.