Concentration of PGMs from automobile catalyst by combining surface grinding and quenching

Spent automobile catalyst is an important secondary resource of PGMs (platinum group metals). The present recovery technologies, including pyro- and hydro-metallurgical processes, are energy-consuming. Automobile catalyst is usually composed of cordierite phase as the substrate covered by the alumina phase which contains PGMs, so the concentration of PGMs could be achieved by separating the alumina phase from cordierite phase using energy saving physical methods. In this paper, according to the structural characteristics of the catalyst, jaw crusher, crushing roll and attritor surface grind were used to concentrate and recover the coat layer into the fine fractions. In order to improve the recovery of coat layer, the heating-quenching process was carried out before the above mentioned crushing. The heating-quenching process produced micro-cracks at alumina/cordierite interface and in the alumina phase because of thermal-stress which was generated by high temperature gradient in the transient thermal conduction. The paper also made a mathematical consideration and FEM (Finite Element Method) simulation to clarify the fracture generation mechanism in the quenching process.