Separation of V(IV) and Fe(III) from the acid leach solution of stone coal by D2EHPA/TBP

Abstract

The separation of V(IV) and Fe(III) from the acid leach solution of stone coal by D2EHPA/TBP was studied. Experimental results showed that V(IV) and Fe(III) can be effectively separated from the solution containing 2.87g/L V(IV), 2.71g/L Fe(II) and 8.45g/L Fe(III) at pH1.22 by fractional extraction with the kerosene solution of 15%(v/v) D2EHPA and 2%(v/v) TBP at room temperature. After 5 stages of counter-current extraction with the solvent at O/A ratio 1:1 contact for 20min, Fe(III) extraction was 91.5% with 9.18% V(IV) co-extracted. The loaded organic phase was first scrubbed with dilute H2SO4 solution to recover the co-extracted vanadium, and then the Fe(III) was stripped with the solution of NaCl saturated in 1.50mol/L HCl. The stripping percentage of Fe(III) was 98.7% by 4 stages counter-current stripping at O/A ratio 1:1 contact for 10min. After the removal of Fe(III), the solution was used as the feed liquid of V(IV) extraction with the regenerated solvent after adjusting the pH to 2.40 by adding CaCO3 under stirring. The extraction percentage of vanadium reached 97.4% by 6 counter-current stages at O/A ratio 1:1 contact for 10min. The vanadium loaded organic phase was stripped with the V(IV) scrubbed solution after adding H2SO4 to increase [H+] to about 1mol/L, and the pure VOSO4 solution containing 13.7g/L V was obtained.