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

Abstract

Silver is recovered from the leaching solution of the spent Ag/α-Al2O3 catalyst by solvent extraction. Most of the silver in the spent catalyst was dissolved by using HNO3 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.

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

“…24) The composition of the resultant leaching solution was as follows: Ag 7.08, Al 0.07, Si 0.04, Ca 0.007, and Re 0.016 g/dm 3 . In the stripping process, only the Ag was considered.…”

“…In our previous study, 24) Ag was selectively extracted from the real leaching solution of Ag/α-Al 2 O 3 catalysts by using 0.5 mol/dm 3 LIX63, leaving the other impurities(Al, Si, Ca) in the raf nate. The co-extracted Re was very low (<1.2 mg/ dm 3 ).…”

“…[13][14][15][16][17][18][19] 5, 8-diethyl-7-hydroxy-dodecan-6-oxime (LIX63) has been used in research and industrial settings to extract many metals, including cobalt, nickel, palladium, gallium, and molybdenum. [20][21][22][23] In our previous study, 24) LIX63 was used to selectively extraction of silver from the nitrate leaching solution of spent Ag/α-Al 2 O 3 catalyst, which contains Ag 7.08, Al 0.07, Si 0.04, Ca 0.007, and Re 0.016 g/dm 3 . Silver was completely extracted with 0.5 mol/dm 3 LIX63 at an O/A (organic to aqueous phase) ratio of 1 for 3 stages.…”

Fabrication of conductive silver paste recovered from leaching of waste catalyst using hydrochloric acid

“…[4][5][6] Palladium and silver catalysts are widely used in petrochemical processes such as carbon bond-forming reactions. [7][8][9][10] Pd and Ag are precious metals (PMs), rare and very expensive. 11 Ag is usually used as an electrode for devices due to its high corrosion resistance and electrical conductivity.…”

Application of Polymer Inclusion Membranes Doped with Alkylimidazole to Separation of Silver and Zinc Ions from Model Solutions and after Battery Leaching

“…In hydrometallurgical processes, solid waste-containing metals, including silver and zinc, are comminuted and then leached [ 22 , 23 ]. For leaching silver, nitric acid is most commonly used [ 24 ]. Additionally, attempts were made to leach waste with thiourea and its derivatives [ 25 ].…”