Density and Surface Tension of Slags from the Joint Smelting of Nickel Saprolite and Copper Pyrite Ores

The density and surface tension of homogeneous molten slags from the joint smelting of nickel saprolite and copper pyrite ores have been experimentally assessed (maximum bubble pressure method) using model samples of iron-containing slage (8.9 wt.% CaO + 11.8 wt.% MgO + 12.5 wt.% Al₂O₃ + 47.4 wt.% SiO₂ + 13.3 wt.% FeO + 5.0 wt.% Fe₂O₃) and iron-free slag (12.5 wt.% CaO + 16.0 wt.% MgO + 9.4 wt.% Al₂O₃ + 58.3 wt.% SiO₂), which represent the composition and structure of real prototypes in the temperature ranges of 1550–1300°C and 1550–1400°C, respectively. A decrease in temperature leads to an increase in the density and surface tension of these slags in the ranges of 1.85–2.21 and 2.23–2.29 g·cm^–3 and 144–250 and 340–345 mN·m^–1, respectively. The structural changes after the change over from the former composition to the latter one are due to the decrease in basicity from 0.7 to 0.6 and the replacement of Fe²⁺ by Ca²⁺ and Mg²⁺. The latter factor makes the major contribution to the increase of the characteristics themselves and their temperature coefficients (from –0.0015 to –0.0004 g·cm^–3·°C^–1 and from –0.4 to –0.1 mN·m^–1·°C^–1, respectively). The regression analysis of the experimental data was performed to obtain empirical models that accurately predict the density and surface tension of real slags from the smelting of copper and nickel raw materials in the temperature range considered. The results obtained can be used in developing and improving metallurgical technologies and in the glass and ceramic industries.