• leaching;
  • palladium;
  • rhodium;
  • spent automobile catalysts;
  • microwave

Leaching of palladium and rhodium from spent automobile catalysts by microwave roasting was investigated. The results indicated that leaching efficiency was obviously improved, the roasting temperature was remarkably reduced and the leaching time was shortened by microwave roasting. Microwave destroys the coatings on platinum group metals and increases the effective contact area of the solid–liquid reaction. The leaching rate was accelerated at low microwave roasting temperatures. The leaching ratio of Pd and Rh was about 99.74 and 94.79%, respectively. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 913–917, 2014