Recovery of metallic content from specific waste streams often creates an unwanted air pollution problem. The most usual dust source is a “fragmentiser mill” which facilitates downstream segregation of materials. Because the feed material is often inconsistent the nature of the pollutants created can often be variable. It would be wrong to assume “dust” is all that the downstream air pollution control system will need to cope with. The amount of energy dissipated in the fragmentiser mill can create a great deal of heat and whilst the exhaust air flow may never be at high temperature the presence periodically of blue smoke or fume in the exhaust indicates that pollutants other than simply dust are to be expected from time to time. For this reason a filter that can deal with many different conditions is essential. AAF regularly supplies the RotoClone N for this application. It can be relied upon to continue working effectively throughout process variations and for this reason is a wise and popular choice. It is available with mechanised sludge ejector system and recent developments mean that it can be operated at higher scrubbing pressures to significantly improve the collection efficiency and meet more stringent emission limits.