Selective Separation and Extraction of Vanadium(IV) and Manganese(II) from Co-leaching Solution of Roasted Stone Coal and Pyrolusite via Solvent Extraction

Novel technology for selective separation and extraction of vanadium(IV) and manganese(II) from co-leaching solution of roasted stone coal and pyrolusite via solvent extraction was used to study the extraction of vanadium(IV) and manganese(II), and many technical conditions have also been optimized. Countercurrent experiments were conducted to verify the results of the experiments. The results indicated that, with three countercurrent extraction stages, 99.13% of vanadium(IV) was extracted by use of 5% (v/v) 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHEHPA) at an initial aqueous pH of 2.0 and an O/A phase ratio of 1:1. Vanadium(IV) could be completely stripped after three-stage countercurrent experiments with 1 mol/L H2SO4 at an O/A phase ratio of 1:1. With three countercurrent extraction stages, 99.74% of manganese(II) could be extracted by use of 40% (v/v) di-(2-ethylhexyl)phosphoric acid (D2EHPA) with 60 mol % saponification efficiency at an initial aqueous pH of 3.5 and an O/A phase ratio of 2:1. Manganese(II) could be completely scrubbed off after two-stage countercurrent experiments with 1 mol/L H2SO4 at an O/A phase ratio of 2:3. A process flow sheet for recovery of vanadium(IV) and manganese(II) is proposed.