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

Abstract

Nitric acid was employed to strip silver from loaded 5,8-diethyl-7-hydroxy-dodecan-6-oxime (LIX63) in the recovery of silver from a leaching solution of a spent Ag/α-Al₂O₃ catalyst. The loaded LIX63 was obtained by contacting the real leaching solution with 0.5 mol/dm³ LIX63 diluted in kerosene. In order to produce silver powder by reduction, the HNO₃ in the stripping solution was recovered by extraction with tri 2-ethylhexyl amine (TEHA) followed by stripping with distilled water. Silver powder was obtained by reduction with 0.1 mol/dm³ L-ascorbic acid. A flowsheet was proposed to recover Ag from the leaching solution of the spent Ag/α-Al₂O₃ catalyst by solvent extraction and reduction with minimum waste emissions.