DE2911855

The hazards to pollution of the environment by metal-bearing dusts and residues are reduced by a process which comprises slurrying the residues in water or a pickling-acid slurry, adjusting the pH of the resultant slurry, when necessary, to 7 or above in order to precipitate compounds of the heavy metals present in the slurry, dehydrating the slurry, and fragmenting the product of the dehydration. A reducing agent may be added to reduce hexavalent chromium if present. The fragments of filter cake can be worked up, in a smelting furnace to yield a metallic body and slag, the flue gas being purified.