Enrichment and crystallization of vanadium in factory steel slag

The distribution behavior of vanadium in factory steel slags with high basicity (CaO/SiO 2 ) and enrichment of vanadium in slag modified by SiO 2 and Al 2 O 3 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 V 2 O 5 contents in the dicalcium silicate phase increase with declining basicity of steel slag, whereas, in the slag modified by SiO 2 and Al 2 O 3 , V is concentrated in the solid solution of Ca 3 [(V, P, Si)O 4 ] 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 Ca 3 [(V, P, Si)O 4 ] 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.