Submicronic dust sepn from powder - esp. from alumina powder, using a fluidised bed with extra air jets

摘要

Purifying powder particles from impurities consisting of a fine dust having dimensions notably smaller than and adhering to the particles, comprises passing the powder through a tank contg. a fluidised bed, the ascending current of gas removing the fine dust. A complementary dynamic action is provided by further currents of gas to remove the dust adhering more tenaciously to the powder and the currents of gas are then combined to carry the fine dust to a gas outlet which can include a filter if required. The pref. devices consist of various types of fluidised beds which may also be vibrated and the pref. application is the removal of fine dust from a powder used in the industrial mfr. of Al. Used e.g. for sepn. of submicronic dust consisting of carbon, oxides of Fe, Ni, cpds. of Na, contaminating alumina powder used for mfg. Al, the alumina having a size between a few microns and several tens of microns.