Abstract:In view of the current research status that it is difficult to separate vanadium and chromium from vanadium chromium slag with high efficiency and environmental protection, vanadium-chromium slag was taken as the research object, and manganese carbonate was used as the roasting additive to achieve the high-efficiency separation of vanadium and chromium by manganese carbonate roasting-acid leaching process. The effects of manganese carbonate content, roasting temperature, holding time and heating rate on the leaching behaviors of vanadium and chromium were studied by orthogonal test design. The results show that, in the roasting process, vanadium spinel combines with the decomposition product of manganese carbonate, Mn₂O₃, to form the acid soluble Mn₂V₂O₇, and then enter the liquid phase after leaching. The stable solid solution (Fe_0.6Cr_0.4)₂O₃ is formed by the combination of chromium and iron, which is transferred into the slag phase after leaching. The leaching rate of vanadium reaches the maximum of 89.37% when the addition amount of manganese carbonate (n(MnO)/n(V₂O₅) is 2.0, the roasting temperature is 850 ℃, the holding time is 2 h and the heating rate is 5 ℃/min. At the same time, the leaching rate of chromium is only 0.10%, realizing the efficient extraction of vanadium and separation of vanadium and chromium.

Key words: vanadium-chromium slag; manganese salt roasting; acid leaching; separation