Density, surface tension, viscosity, and slag–refractory interaction of industrial copper-making slag with MgCr2O4 refractory furnace lining

The thermophysical properties and refractory interaction behavior of two industrial copper-making slags from the Almalyk Mining and Metallurgical Combine (Uzbekistan) were investigated. The slags originate from a Vanyukov furnace (VF, FeO x /SiO 2 = 1.93) and an oxygen-flame furnace (OFF, FeO x /SiO 2 = 1.57). Density and surface tension were determined by the maximum bubble pressure method, viscosity by the rotating bob method, and wetting behavior by the sessile drop method on MgCr 2 O 4 refractory substrates. Post-test cross-sections were examined by SEM–EDX. At the industrially relevant copper smelting temperature of 1350 °C, VF slag exhibited higher density (3281.99 versus 3242.88 kg/m 3 ), higher surface tension (302.54 versus 284.55 mN/m), and lower viscosity (188.90 versus 210.41 mPa·s) than OFF, consistent with its higher FeO x content and the associated depolymerization of the silicate network. Both slags showed characteristic viscosity break temperatures at 1243 °C and 1100 °C. Sessile drop experiments revealed faster infiltration of VF into the refractory at 1070-1150 °C, driven primarily by its lower viscosity. SEM–EDX identified spinel, olivine, and magnesiowüstite corrosion products. VF promoted volumetric refractory degradation, whereas OFF formed a thin surface reaction layer. The FeO x /SiO 2 ratio controls the thermophysical properties of slag. This demonstrates the trade-off between optimizing fluidity for metal recovery and extending refractory service life.

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