Recovery of H2SO4 from an acid leach solution by diffusion dialysis

Diffusion dialysis with a series of anion exchange membranes was used to recover H2SO4 from an acid leach solution produced during the vanadium manufacturing process. The effects of sulfuric acid, FeSO4 and VOSO4 concentration, flow rate and flow rate ratio on the recovery of H2SO4 were investigated. The results showed that sulfuric acid permeated well through the membranes used, while metal ions were efficiently rejected. The recovery of H2SO4 increased as the sulfate concentration of the feed increased and the flow rate ratio of water to feed increased. More than 80% of the H2SO4 could be recovered from the leach solution which contained 61.7 g/L free H2SO4, 11.2 g/L Fe and 4.60 g/L V at a flow rate of 0.19 x 10-3 m3/h m2. V and Fe ion rejection were within 93-95 and 92-94%, respectively. A preliminary economic evaluation revealed that an investment in this process could be recovered within 27 months.