Enrichment and crystallization of vanadium in factory steel slag

Abstract

The distribution behavior of vanadium in factory steel slags with high basicity (CaO/SiO2) and enrichment of vanadium in slag modified by SiO2 and Al2O3 were investigated. The mineralogical phases and vanadium distribution were characterized by scanning electron microscopy (SEM), energy disperse x-ray spectrometry (EDS), and powder x-ray diffraction (XRD). The results indicate that vanadium is distributed in the major phase of calcium silicate and the phase of the matrix in steel slag with high basicity. The V2O5 contents in the dicalcium silicate phase increase with declining basicity of steel slag, whereas, in the slag modified by SiO2 and Al2O3, V is concentrated in the solid solution of Ca3[(V, P, Si)O4]2 (the V-enrichment phase), which is identified with the results based on synthetic steel slag containing vanadium. The relation between chemical composition and crystallization behavior and grain size of Ca3[(V, P, Si)O4]2 is also discussed. It is found that high MgO in the slag will form magnesium aluminate, and the V-enrichment phase grains grow larger than that obtained in synthetic slag.