Richer scrap is smelted with coke and litharge in a reverberatory furnace, again resulting in a slag, matte and lead bullion. Silver is recovered from the bullion by preferential oxidation (cupellation) of impurities while gold recovery is achieved by chlorination (Miller process) with final electrorefining of each. Anode slimes from silver electrorefining are processed by leaching with H2SO4 or HNO3. The Cu is cemented out with iron, and Ag and Rh subsequently cemented with Cu powder. The ‘gold sand’ left after leaching is treated electrolytically to reclaim fine Au, leaving the platinum group metals to be recovered from the spent electrolyte. Effluents from the plating industry are an important source of precious metals. Liquors containing Ag from the photographic processing operations are normally processed at source or by a local consortium and subsequently electrolytically refined.