Formation and phase-mineralogical composition of converter slags

Vanadium slag samples, which are taken at various stages of the converter devanadation of lowsilicon (0.05–0.15% Si) cast iron and after cooling in converter pans, are studied by electron-probe microanalysis and X-ray diffraction. The evolution of the compositions of spinelide, silicate, and metallic phases is investigated. The experimental results are compared with the well-known formation mechanism and the phase composition of the slags of the devanadation of silicon cast irons during oxygen or air blowing. It is shown that, despite the differences in the compositions and the grain sizes of a spinelide phase, the mechanism of its formation at the initial stages of oxidation of cast iron elements with different silicon contents is the same. The spinelide composition and the element distribution over a grain depend on the cast iron composition and the quantity and composition of the silicate phases that form during devanadation in a converter and upon cooling of a slag ingot