Separation and recovery of vanadium from a sulfuric-acid leaching solution of stone coal by solvent extraction using trialkylamine

• Trialkylamine-N235 was used to recover of vanadium from acidic solution with massive impurities.
• Various extraction effects were investigated.
• The organic system had high efficiency to separate vanadium from massive impurities.
• A process flow sheet for vanadium extraction was established.

Trialkylamine-N235, diluted with sulfonated kerosene containing tri-butyl phosphate, was used to separate vanadium and impurities as Fe, Al, Mg, K, Ca, P, and Si from a leaching solution generated by the sulfuric-acid leaching of vanadium-containing stone coal. Variations in aqueous pH exhibited good extraction of vanadium at an equilibrium pH of 1.6. Vanadium was successfully extracted by a three-stage countercurrent process using 20% N235 and 5% tri-butyl phosphate at an organic-to-aqueous (A/O) phase ratio of 2:1. The loaded organic was then scrubbed with 0.5 mol/L H2SO4, and most impurities were scrubbed by three-stage scrubbing. 1.0 mol/L NaOH was used to strip of vanadium from the scrubbed organic solution at an O/A phase ratio of 2:1, where >99% of vanadium was stripped in three stages. After regeneration by 1.0 mol/L H2SO4, the regenerated organic phase showed a good performance on vanadium extraction even after 5 cycles. Finally, a process flow sheet was established to recover of vanadium from a sulfuric-acid leaching solution of stone coal.