Material composition of magnetic fractions of copper-smelting slag flotation tailings

Finely ground tailings from flotation processing of waste copper reverberatory smelting slags of the Sredneuralsky Copper Smelter ("SUMZ technical sands") was accumulated in significant amounts and may pose a threat to the environment as a potential source of heavy metals. At the same time, the waste can be considered as a promising source of useful components due to relatively high contents of zinc (3.3–3.9%) and copper (0.4–0.5%). Development of technologies for recycling the "technical sands" is a promising task of nonferrous metallurgy and requires their comprehensive study. The purpose of this research was to study the material composition of magnetic fractions of the "SUMZ technical sands" and assess the prospects of extraction of useful components (zinc and copper) from their flotation tailings using wet magnetic separation. Chemical analyses of the obtained fractions were carried out at the Center for Collective Use "Geoanalitik" of the Institute of Geology and Geochemistry, UB RAS by inductively coupled plasma mass spectrometry method using an Elan-9000 quadrupole mass spectrometer. Phase analyses were carried out at the Ural-M Collective Use Center of the Institute of Metallurgy, UB RAS by X-ray phase analysis using a Bruker D8 Advance diffractometer. The magnetic properties of the magnetic separation fractions were studied by thermomagnetic analysis. After treating the tailings by wet magnetic separation, the yield of the magnetic fraction (48 kA/m) was approximately 83%, that of the weakly magnetic fraction (200 kA/m) was 11%, and that of the non-magnetic fraction, 6%. The data on the phase and chemical composition of the tailings magnetic separation fractions were obtained. It was found that zinc and copper were distributed relatively uniformly among the fractions with a slightly higher content of copper in the non-magnetic fraction and that of zinc in the weakly magnetic fraction. The dependence of magnetic susceptibility of the "technical sands" minerals on the presence of isomorphic impurities in them was confirmed. The joint evaluation of the data of X-ray phase and thermomagnetic analyses showed that at practically identical X-ray diffraction patterns the thermomagnetic curves in the range of 20–700°C demonstrate significant differences between the magnetic separation fractions. All the obtained thermomagnetic curves are irreversible. At the used parameters of wet magnetic separation, this method proved inefficient for the "technical sands" separation, and additional research is required to find optimal methods of the tailings pretreatment and magnetic intensity modes. The research findings contribute to the study of magnetic properties of copper-smelting slag processing tailings and are of interest for the development of new flow schemes for their utilization and recycling.