Abstract: An air sifting apparatus is provided for preparatory concentration of raw material including coal, and includes a material feed-in device, a material bed support device, an air jig plenum, and a discharge control device. The material bed support device receives material from the material feed-in device and has a surface having a plurality of openings for a gaseous medium introduced from underneath the material bed support device, which is operable to transport material in coordination with the flow of gaseous medium through the openings to effect loosening and stratification of the material into a layer of relatively heavier material, and a layer of relatively lighter material on the heavier material. The air jig plenum communicates with the underside of the apparatus for guiding gaseous medium thereto and produces constant air flow through the openings of the support device and a pulsating air flow, overlaid on the constant air flow, for pulse impacting material on the support device.

Abstract: An air sifting apparatus is provided for preparatory concentration of raw material including coal, and includes a material feed-in device, a material bed support device, an air jig plenum, and a discharge control device. The material bed support device receives material from the material feed-in device and has a surface having a plurality of openings for a gaseous medium introduced from underneath the material bed support device, which is operable to transport material in coordination with the flow of gaseous medium through the openings to effect loosening and stratification of the material into a layer of relatively heavier material, and a layer of relatively lighter material on the heavier material. The air jig plenum communicates with the underside of the apparatus for guiding gaseous medium thereto and produces constant air flow through the openings of the support device and a pulsating air flow, overlaid on the constant air flow, for pulse impacting material on the support device.