METHOD OF REPROCESSING ZINC-AND LEAD-CONTAINING RESIDUES FROM METALLURGICAL PLANTS

摘要

Steel works residues containing zinc and lead are worked up by thermal treatment in a circulating fluidised bed, the heat required being met predominantly by combustion of solid carbon in the fluidised-bed reactor of the circulating fluidised bed. A reducing fluidisation gas which contains virtually no free oxygen is passed into the lower part of the fluidised-bed reactor. The content of solid carbon in the lower part of the fluidised bed is adjusted to 5 to 30%. Oxygen-containing gases are passed into the upper part, and CO2 formation is permitted to continue only to such an extent that metallic zinc is not reoxidised. The discharged suspension is substantially freed from solid in a recycle cyclone, and the solid is recycled. The gas is cooled to a temperature at which the metallic zinc is oxidised to ZnO, and the dust-like zinc and lead compounds are deposited from the gas.