Sustainable Valuable Metal Recovery from the V-Cr-Fe Ternary Slime via Leaching-Selective Complexation

The V-Cr-Fe ternary slime is an emerging heavy metal waste after a series of pyro- and hydro-metallurgical processes (the so-called "slime of the slag"), usually containing considerable metal resources and nearly 70 wt % H2O inside. In this study, a facile leaching complexation method is proposed for the cleaner, efficient, and selective recovery of V, Cr, and Fe. After efficient leaching procedure in the H2SO4 solution, 94% V and 97% Fe were selectively precipitated out via the complexation with C5H10NNaS2. Subsequently, the V and Fe could be further separated through the dissociation in alkaline solution, in which the Fe(OH)(3) solid and Ca2V2O7 (with the addition of CaO) were generated, respectively. Furthermore, the complexing agent could be regenerated for next cycles, minimizing the potential secondary wastewater or solid waste formation. As a result, a cleaner and sustainable metal recovery method was developed, providing further understanding of the solution chemistry and separation technologies