Fabrication of spherical magnetite particles by the flame fusion method

摘要

Fabrication of spherical magnetite powders wasinvestigated in the propane-oxygen flame using sponge ironpowders as a starting powder. Spherical particles produced byfusion, sphering and oxidation of iron powder were composed ofresidual Fe, FeO, Fe3O4 and α-Fe2O3 in the case of particlescollected by a cyclone. The amount of Fe3O4 in the products wasstrongly dependent on the propane/oxygen ration and the flowrate of carrier air, but weakly on the feed rate of iron powder.Injection of quenching gas was found to be effective to improvethe yield of Fe3O4. Particle size of products reflected directlythat of starting powders, indicating fairly easy control of particlesize of products. The saturation magnetization of the producedpowder under the optimum condition was 88 emu/g.