Wettability and corrosion behavior between alkaline slag from sodium smelting of vanadium–titanium magnetite and refractory substrates

The sodium smelting of vanadium–titanium magnetite can achieve the comprehensive utilization of Fe, V, and Ti. However, the generation of alkaline slag during this process may cause damage to refractory materials. The wettability and corrosion behavior of alkaline slag on three types of refractory (MgO–C, SiC, and high alumina refractory) substrates were investigated at temperatures up to 1200 °C. The effects of duration on the wettability of molten slag on SiC substrates were also investigated. Results showed that the high alumina refractory exhibited better wettability with the molten slag than the others, and thus, it is easier to be corroded. The results of scanning electron microscopy coupled with energy dispersive spectroscopy showed that MgO–C and high alumina refractory substrates were severely eroded. There was a visible and regular interfacial reaction layer between the slag and SiC refractory substrate, which was produced by the redox reaction between the metal oxides in the slag and the SiC refractory substrate. With the increase in holding time, the interface layer expands and silico-ferrite phases are generated at the interface. The redox reaction between Fe2O3 and SiC substrate is the main reason for the corrosion. By comparing the differences in wettability and corrosion behavior between the alkaline slag from sodium smelting of vanadium–titanium magnetite and MgO–C, SiC and high alumina refractories, it is concluded that SiC refractory has good corrosion resistance to the slag. Iron oxides in the slag accelerate the oxidation rate of SiC refractory.