Recovery of oxalic acid from mother-liquor containing hydrochloric acid and cobalt by solvent extraction with P350
(School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China)
Abstract: The solvent of P350 was applied to extract and separate the oxalic acid from the mother-liquor originated from the precipitation of cobalt by oxalic acid, and its extraction mechanism was deduced. Some factors, including the concentration of P350, the concentration of hydrochloric acid and the concentration of oxalic acid were investigated to determine the best distribution coefficient of the oxalic acid. In the case of phase ratio (O/A ) at 2.0, the extraction of the oxalic acid was more than 95% and its concentration in the extraction raffinate was lower than 0.004 0 mol/L after six-stage counter-current extraction. While the phase ratio (O/A) of the stripping was at 1.0, the recovery of oxalic acid attained more than 95% after ten-stage counter-current stripping.
Key words: P350; counter-current; solvent extraction; oxalic acid; stripping