PRODUCTION OF RAW MATERIAL POWDER FOR PERMANENT MAGNET

摘要

PURPOSE:To produce the titled powder from which extra fine powder is removed and which consists of single fine particles without flocculation by heating the specified ferromagnetic pulverous powder at a specific temp. in a vacuum, blowing the powder together with an inert gas into a classifying vessel and classifying the powder with the secondary inert gas near the central part of the vessel. CONSTITUTION:The ferromagnetic pulverous powder for a permanent magnet having <=550 deg.C Curie temp. and <=10mu grain size is heated in the vacuum or inert gas to the temp. range above the temp. lower by 50 deg.C than said Curie temp. and <=850 deg.C. The heated powder is blown together with the heated inert gas from a feed pipe 2 of the classifying vessel 1 and the secondary inert gas of the same temp. as the temp. of the powder is blown through feed ports 3 in the tangential direction distributed evenly in the central part of the vessel wall. The extra fine powder in the raw material powder is thus separated and gathered in the central part by centrifugal force and is taken out of a discharge port 5. The other pulverous powder is recovered from a take-out port 4.