Abstract: For thermally treating waste and/or residual materials, in particular fiber glass, glass silk, glass wool and glass mat coated with organic materials, a drum (1) with embedded elements is used to make the materials circulate. In this drum the materials are heated up to a temperature at least equal to the carbonization and/or evaporation temperature of the coatings but lower than the softening temperature of the materials. The waste or residual materials are preferably increasingly disaggregated in the drum and are heated by a stream of hot gas which flows in the drum from the discharge side (11) to the inlet side (4) and has its highest temperature at the discharge side.