PROCESS AND DEVICE FOR RECOVERING RAW MATERIALS FROM WASTE AND RESIDUES

A process is disclosed for recovering raw materials, in particular heavy metals such as chromium, zinc, copper, lead, or nickel, by separation from waste and residues, wherein a liquid or viscous starting mixture and/or a starting mixture composed of crushed or ground components is first prepared. The invention is characterized in that the raw materials are separated by a thermochemical treatment. The liquid, viscous and/or solid starting mixture is first mixed with additives, depending on its composition, then subjected to a thermal treatment in an oven. The atmosphere in the oven flows through the starting mixture and the suspended materials thus generated as flakes or dust are conveyed out of the oven through a filter installation with several stages in which they are separated from the waste gas. The first filter is designed as a hot filter, after which the waste gas is cooled and after flowing through at least a second filter, pre-heated and then burnt at a high temperature. The process of the invention may be used, for example, to recover chromium (III) oxide from chromium-containing residues or zinc oxide from zinc-containing residues. Formation of chromium (III) oxide from chlorine-containing wastes occurs by formation and decomposition of chromyl chloride. Additives suitable for use in the invention may include those that comprise aluminum, aluminum oxide, iron, iron oxide, chlorine-containing material, sulfur-containing, milled plastics, granulated plastics, peroxides, silicon oxide, magnesium oxide or combinations thereof.