Separation and recovery of molybdenum, vanadium and nickel from a sulfuric acid-leaching solution

The deep separation of molybdenum (Mo), vanadium (V), and nickel (Ni) from acid-leaching solutions has received increasing attention because of the high value of Mo, V and Ni materials. In this study, an efficient strategy is proposed to separate Mo, V, and Ni from an acidic solution that contains iron (Fe). This strategy controls the ion species by adjusting the valence state of the metals to separate them via two stages: selective solvent extraction and oxidation precipitation. In the first stage, more than 99.0 % of the Mo in the form of molybdenum blue species as the anion ion was extracted by the tertiary amine N235, and V, Ni, and Fe (both as the cation ions) remained in the raffinate under the reduced environment. The high-purity product of Mo was then prepared by stripping and precipitation. The mechanism by which Mo selectively extracted was revealed by Fourier transform infrared spectroscopy, and the special anion [Mo(VI)2Mo(V)4O18]6- of molybdenum blue species was confirmed to exist in the Mo-loaded extractant. In the second stage, the reduced V(VO2+) and Fe (Fe2+) were transformed into the forms of polyvanadate ions (in the + 5 state) and Fe3+ to precipitate them in the forms of sodium vanadate and iron vanadate from the solution that contained Ni, by adding oxidating agent and controlling the solution pH. The results shown that 96.88 % of V and 98.98 % of Fe could be precipitated under the pH was 3.0, and the mechanisms of V and Fe precipitation were determined by characterization of the precipitates subsequently. On the basis of ion species control, the goal of Mo, V, and Ni separation could be achieved by the selective extraction of N235 and oxidation precipitation.