In Germany about 5 million tons of municipal solid waste incineration (MSWI) bottom ashes are treated for metal recovery annually. With the actual processing metal recovery is realized down to 2 mm. The fractions < 2mm are utilized without metal recovery. Due to high residual concentrations of non-ferrous metals in these fractions, especially Cu, several thousand tons of metals are lost every year. This article presents an approach to recover Cu of fine fractions < 0.2mm by froth flotation. Several collector regimes are screened and flotation parameters are varied. First results exhibit Cu recoveries of 50% with Cu concentrations of about 5%.