Effect of chromium content on the phase composition, crystallization and components extraction of vanadium slag

Abstract

The existence of chromium in vanadium slag is generally considered to affect its phase composition, micromorphology, and further vanadium extraction by calcification roasting process. In this work, remelting and crystallization were used to prepare vanadium slag with different Cr2O3 mass fractions. The aforementioned effects were then examined through X-ray diffraction, scanning electron microscope, and leaching experiments. Results showed that Cr2O3 content affects spinel phase in vanadium slag. With the increase in Cr2O3 content, chromium was observed in the (Mn, Fe)(V, Cr)2O4 phase with vanadium in a homogeneous form, while the diffraction peak positions of (Mn, Fe)(V, Cr)2O4 shifted by a large angle from the lattice distortion. Further, the average grain size of spinel gradually decreased because of the increase in the number of crystallization centers, and the distribution of Cr, V, and Ti in the spinel phase were gradually homogenized instead of having obvious stratification. After calcification roasting, vanadium and chromium existed in the form of vanadate and (Fe0.6Cr0.4)2O3, achieving the complete separation of them after acid leaching. The increase in Cr2O3 content had no significant effect on the leaching behavior of vanadium. Additionally, increasing the roasting temperature and accelerating the heating process contributed to restraining chromium extraction. These results provide a research basis for the resource utilization of vanadium slag and vanadium chromium slag.