Application of Sulfide Copper Ores Oxidizing Roasting Products as Sulfidizing Agent During Melting Nickel Raw Materials To Matte

Abstract

X-ray fluorescence analysis, X-ray powder diffraction, electron microprobe analysis, scanning electron microscopy, and thermal analysis are used to evaluate the material composition, structure and thermal properties of Dergamysh ore deposit and condensed roasted (750–850°C) products. Ore heating in air is accompanied by oxidation of sulfur and iron oxides, combustion and decomposition of sulfides, carbonate thermolysis, and decomposition of iron, copper, and zinc sulfates. Processes are generally completed up to 850°C. With desulfurization to the level of 60–94% sulfur the ore retains a porphyroblastic structure. Crystals (1–5 μm) of hexagonal and monoclinic pyrrhotites, corresponding to the general formula Fe0.80−0.93S, sphalerite and bornite border a mixture of fine (1 μm) olivine and spinel. In this case sulfides and oxides in contact with them achieve a similar concentration of non-ferrous metals, wt.%: up to 0.7 Co, 1.5–21.8 Cu, and 1.1–56.6 Zn. Heating a mixture of roasted (70–80% desulfurization) sulfide copper ore with nickeliferrous saprolite ore, calcium oxide and carbon in a weight ratio of 60:100:10:2.5 provides matte (4.1 wt. % Ni, 2.5 wt. % Cu, 0.38 wt. % Co, 2.1 g/ton Au, and 3.6 g/ton Ag) concentrating 90.3% nickel, 82.7% copper, 85.3% cobalt, and up to 99.0% of precious metals. The products of oxidation roasting of sulfide copper ores can be considered as an effective sulfiding agent and collector of valuable metals during smelting of nickeliferrous saprolite ores. The technology of joint reduction and sulfiding smelting of roasted copper ores and calcined saprolite ores is a promising way to use poor and mineral raw materials that are hard to enrich and to reduce SO2 emissions into the atmosphere.