Recovery of Silver from the Nitrate Leaching Solution of the Spent Ag/α-Al₂O₃ Catalyst by Solvent Extraction

Silver is recovered from the leaching solution of the spent Ag/α-Al 2 O 3 catalyst by solvent extraction. Most of the silver in the spent catalyst was dissolved by using HNO 3 solution. The parameters such as concentration of lixiviant, reaction temperature, pulp density, and stirring speed, which might affect the dissolution of silver from the spent catalyst, were investigated. McCabe-Thiele plots predicted that complete extraction of Ag from the leaching solution could be obtained with LIX63 at an O/A ratio of 1 in 3 stages, while complete stripping of Ag from the loaded LIX63 could be obtained with thiourea at an A/O ratio of 1 in 2 stages. Countercurrent extraction and stripping simulation tests were carried out to confirm this prediction. More than 99.89% of Ag with purity of 99.91% was recovered from the leaching solution. Finally, a complete flow sheet of the process for separation and recovery of Ag from the spent catalyst was demonstrated.