Deep understanding of sustainable vanadium recovery from chrome vanadium slag: Promotive action of competitive chromium species for vanadium solvent extraction

The complete separation of vanadium (V) and chromium (Cr) from chrome vanadium slag is still challenging. Many studies focus on the activity of vanadium, while the effect of the other element chromium and their mutual interaction are ignored. Here, we found that proper concentration of chromium can promote the extraction efficiency of vanadium. The extraction of V and Cr with various mass ratios ranging from 8:1–4:3 at different initial pH values using primary amine N1923 were studied. The extraction efficiency of V reached nearly 100%, while none of Cr was extracted when the mass ratio of Cr and V is 0.5 under proper pH. Through the dynamic monitoring of species evolutions during extraction, the transformation of the two metals and advantage extracted species were analyzed. Cr would transfer H+ for the combination of V3O93-/V4O124-, providing a great contribution to the continuous extraction of V. The real leachate was applied and 99.9% vanadium pentoxide was produced at a scale of 50 L/h. This paper offers deep insights of the separation of similar metal elements, and guide sustainable vanadium recovery from hazardous waste. [Display omitted] •Promotive action of competitive chromium species was explored.•The extraction efficiency of vanadium increased under proper addition of chromium.•The transformation and advantage extracted species of V and Cr were discussed.•Chromium species contributed continuous extraction by offering acid.•This paper encourage people to focus on the metal species transformation.