Abstract: A feeder for highly abrasive materials includes a housing and an impeller. The housing includes inner an outer concentric, spaced apart, vertically oriented wall portions which are each closed at their lower ends by a common bottom plate and at their upper ends, respectively, by vertically spaced apart top plates. The impeller is disposed in the gaps between the wall portions and the top plates and consists of a pair of, spaced-apart, vertically oriented cylindrical members which are joined in a concentric relation by a plurality of radially extending, equi-spaced apart fins. The fins extend upwardly from the lower edges of the cylindrical members and terminate below their upper ends to define a plurality of compartments having equal volumes. The impeller is secured at its upper end to a shaft extending downwardly through the upper-most top plate and along the impeller axis so that the impeller may be rotated to sequentially position each compartment above an opening in the bottom plate.

Abstract: A system for removing hydrogen fluoride, finely divided solids and hydrocarbons from aluminum production process emissions includes a vertical scrubbing chamber of constant cross section for receiving the emissions, and an injector disposed axially within the scrubbing chamber for injecting finely divided alumina particles radially into the emission stream, and a filtering device for capturing the alumina particles and entrapping pollutants.