Abstract: This invention describes a method of reprocessing zinc- and iron oxide-containing residual material. Zinc- and iron oxide-containing dust and/or sludge is granulated with water, granules and carbonaceous material are fed to a circulating fluidized bed system, the gas-solids suspension circulated in the circulating fluidized bed system is fed to a second fluidized bed reactor, the solids discharged from the second fluidized bed reactor are recycled to the reactor of the circulating fluidized bed system, 50 to 75% by volume of the oxygen required to gasify the carbonaceous material are fed as fluidizing gas to the reactor of the circulating fluidized bed system and 25 to 50% by volume of said required oxygen are fed as a fluidizing gas and secondary gas to the second fluidized bed reactor, iron oxide-containing material is discharged from the reactor of the circulating fluidized bed system and zinc-containing material is discharged with the exhaust gas from the circulating fluidized bed system.

Abstract: Residual metallurgical materials which contain zinc and lead are reprocessed by a thermal treatment in a circulating fluidized bed. The required heat is generated in that solid carbon is combusted in the fluidized bed reactor of the circulating fluidized bed. A solid carbon content of 5 to 30% is maintained in the lower part of the fluidized bed. Oxygen-containing gases are supplied to the upper part of the fluidized bed reactor, and CO.sub.2 is formed only in such an amount that zinc metal will not be reoxidized. Substantially all solids are removed from the discharged suspension in a recycle cyclone and are recycled. The gas is cooled to a temperature at which zinc metal is oxidized to ZnO. The dustlike compounds of zinc and lead are separated from the gas.

Abstract: A zinc- and lead-containing residue from a metallurgical plant is reprocessed by a thermal treatment in a circulating fluidized bed system. A major part of the heat demand is satisfied by a combustion of solid carbonaceous material in the fluidized bed reactor of the circulating fluidized bed system. A reducing fluidizing gas, which is virtually free of free oxygen, is fed to the lower part of the fluidized bed reactor. A solid carbon content of from 5 to 30% is adjusted in the fluidized bed in the lower portion of the fluidized bed reactor, which is supplied in its upper portion with oxygen-containing gases and in which CO.sub.2 is formed only at such a rate that zinc metal is not reoxidized. Substantially all solids are removed in a recycling cyclone from the suspension discharged from the reactor and the removed solids are recycled. The gas is cooled to a temperature at which zinc metal is oxidized to ZnO. The dust-like zinc compounds and lead compounds are removed from the gas.