Regeneration and sulfur recovery of Lanxess Lewatit AF 5 catalyst from the acidic Albion leaching process using toluene and tetrachloroethylene as organic solvents

Abstract

The removal of elemental sulfur from the final leach residue produced during the atmospheric oxidative leaching of chalcopyrite concentrates is both a technical and an economic challenge. Lanxess Lewatit® AF 5 catalyst is a promising candidate material that can collect this elemental sulfur during the leaching process. However, to be cost-effective it is necessary to develop methods to regenerate and recycle the AF 5. In the present research, toluene and tetrachloroethylene were studied as potential organic solvents for the removal of the sulfur from the sulfur loaded AF 5. Also, the recovery of elemental sulfur from the resulting liquor was investigated. The effects of temperature, time and AF 5 to solvent ratio on sulfur removal from the sulfur loaded AF 5 were examined. The optimum desulfurization conditions were 100 °C for toluene and 110 °C for tetrachloroethylene for an AF 5 to solvent ratio of 1:50 and a processing time of 120 min. For toluene and tetrachloroethylene, the sulfur removals were 89.8% and 88.1%, respectively. Toluene was considered to be the most promising solvent due to its higher sulfur removal efficiency and a reduced effect on the behavior of the recycled AF 5 in the leaching process. After three consecutive leaching and regeneration cycles the sulfur absorption capacity and the copper and iron leaching recoveries were essentially unchanged. Copper and iron recoveries of greater than 95% and greater than 80%, respectively, were achieved with the recycled AF 5.