Solubility investigations in the NaOH–Na3VO4–Na2CrO4–Na2CO3–H2O system at (40 and 80) °C

To realize the effective separation of Na3VO4, Na2CrO4 and the impurity Na2CO3 in a newly developed vanadium production process using concentrated alkaline solution as reaction media, the equilibrium liquid phase solubility and solid phase compositions of the NaOH–Na3VO4–Na2CrO4–Na2CO3–H2O system at (40 and 80) °C were measured. The obtained solubility data were afterwards compared with quaternary NaOH–Na3VO4–Na2CrO4–H2O subsystem to investigate the salting-out effect of Na3VO4, Na2CrO4 and Na2CO3. Further, a strategy for effective separation of Na3VO4 and Na2CrO4 from the NaOH–Na3VO4–Na2CrO4–Na2CO3–H2O pentabasic system has been proposed on the basis of detailed analysis of crystallization zones.