GAS CIRCULATING TYPE POWDER CLASSIFIER

PURPOSE:To classify combustible powder by means of a simple structure by circulating non-combustible gas in a circulating line to refluxed gas flow from a discharge pipe of a classifier into a case and classifying the powder. CONSTITUTION:Air in a closed case 6 is sucked in from around a classifier 4 into a pump 11 through a cyclone 7 and a filter 9 and the pump 11 by driving a pump 11, and the air sucked in from a closed case 6 is discharged by opening an air discharge valve 19. When the air in the closed case 6 is almost discharged, the air discharge valve 19 is closed and a nitrogen injection valve 18 is opened to inject nitrogen of given volume, and then the nitrogen injection valve 18 is closed. When a powder to be classified is fed from a feeding inlet 1, the powder is fed into the classifier 4 by a screw feeder 2 and classified. The classifier 4 is operated in the nitrogen atmosphere, and conventional classifier and its piping system can be used as carrier by simply closing the classifier, and classification of combustible powder can be carried out by means of a simple structure.