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

The existence of chromium in vanadium slag is generally considered to affect its phase composition, micro -morphology, 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)(2)O-4 phase with vanadium in a homogeneous form, while the diffraction peak positions of (Mn, Fe)(V, Cr)(2)O-4 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)(2)O-3, 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.

Automated summary

This study investigated the effect of Cr2O3 content in vanadium slag on its phase composition and micro morphology. The results showed that increasing Cr2O3 content led to a decrease in the grain size of the spinel phase and a homogenization of the distribution of Cr, V, and Ti. Acid leaching experiments demonstrated that after calcification roasting, vanadium and chromium existed in the form of vanadate and (Fe0.6Cr0.4)2O3, achieving complete separation.