Classification of de-dusting residues

In steel mill as well as in cement mills large amounts of dust are generated and separated from the off-gas by dust separators. The resulting residues are fine grained and enriched in components volatile under the process conditions like zinc, lead and alkali chlorides. The concentration of the re-condensed matter is higher in fine particles. Since these components are often problematic in the recycling of the residues, the removal of the finest size fraction from the residues can improve recycling possibilities. In some cases, the enriched fine fraction could also be used for the recovery of the volatile components as products. For the separation of the finest size fraction of de-dusting residue air classification would be appropriate because of the required cut size of the classification of few micrometre.