Selective recovery of Rhenium from industrial leach solutions by synergistic solvent extraction

In our previous work, the selective precipitation of rhenium from an acidic washing solution present in the copper smelting process was studied. The precipitate formed is a polymetallic sulfide that contains rhenium, copper, arsenic, and bismuth. To recover rhenium from the precipitate, the separation of perrhenate ions from industrial leach solutions using synergistic solvent extraction was investigated. For the synergistic extraction system of Alamine 336 and TBP, Alamine 336 is the primary compound that combines with the anions in the leach solution. The solubility of the extraction complex in the organic phase is enhanced by TBP bonding with the neutral complex. For the extraction of perrhenate ion from the chloridizing leach solution, the difference in the distribution coefficient of rhenium and bismuth is small due to the formation of bismuth polychloride complex ion in aqueous solution. For the acidic leach solution using sulfuric acid and ammonia persulfate, the separation percentage of perrhenate ion is more than 99.90 wt% using four-stage countercurrent extraction. This is because the bismuth and arsenic in the leach solution forms an insoluble compound (BiO)(2)SO4 and arsenic acid. The loaded organic phase is stripped by a 4 mol/L ammonium solution, recovering 98.78% Re. The content of arsenic, copper, bismuth, and lead in the ammonia perrhenate formed from the evaporation and crystallization process using the stripping liquor is less than 0.5 mg/kg and 1.0 mg/kg, respectively.