Pyrometallurgical treatment of silver-containing catalysts

Abstract

The following article describes the thermal process for the recovery of used silver from Ag catalysts using an 80-kVA plasma reactor, along with an appropriate flux and reducing agent. An Ag catalyst was melted in three separate experiments with different weights. The overall recovery of silver from the melted Ag catalysts was high (93.8-96.4) %. The byproducts of the melting of the Ag catalysts were the inert vitrified slag, synthesis gas and fly ash. The chemical analysis of fly ash confirmed that, in addition to mechanically stripped oxides that were present in the batch (CaO, SiO2, MgO, and Al2O3), fly ash also contained a high amount of condensed silver. Indeed, silver evaporated at a high temperature during the melting process. The silver condensed in fly ash was at a level of 37.08-48.37 % of the total weight of fly ash. Therefore, fly ash had to be recycled. The synthesis gas from the process had a relatively low heating value (0.6335 MJ m(-3)).