Extraction and separation of vanadium from high-acidity stone coal leaching solution using N235 coupling with hydrogen peroxide

To enhance the efficiency of vanadium extraction and separation from high-acidity stone coal acid leach solution, a novel method based on hydrogen peroxide oxidation and coordination of vanadium ions was proposed in this study. Vanadium was effectively extracted from the high-acidity stone coal leaching solution through a synergistic process involving H2O2 oxidation coupled with trialkylamine (N235) extraction. The results indicated that the single-stage vanadium extraction efficiency reached 96.99 % under optimal conditions, using 30 % N235 (v/ v) and 70 % sulfonated kerosene as the organic phase, with an initial acidity of 1.5 mol/L, an organic/aqueous phase ratio (O/A) of 2:1, a temperature of 30 degrees C, and an extraction time of 20 min. The V-loaded organic phase was effectively stripped by a mixed solution of sulfuric acid-ascorbic acid. the content of V in the stripping aqueous solution reached up to 19.94 g/L, while impurities (Fe, Al, Mn, Si, and Ca) remained below 0.05 g/L. The mechanism of vanadium extraction using the H2O2-N235 synergistic system was investigated through slope analysis, saturation extraction experiments, Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and quantum chemical calculations. Results confirmed that under the oxidation and coordination action of H2O2, vanadium ions were converted from VO2+ cation into stable peroxovanadate anion VO(O2)2-, which were subsequently extracted into the organic phase via an anion-exchange mechanism, forming [VO(O2)2(R3NH)] complexes. This study addresses the challenges of vanadium extraction from high-acidity stone coal acid leach solution, providing valuable insights for vanadium recovery in industrial applications.