Preparation of mixed metal oxides by thermal decomposition of metal salts

摘要

A magnetic metal oxide compound, e.g. a ferrite, is formed by disintegrating into droplets a feed material solution, suspension, slurry or melt containing thermally decomposable salts of the appropriate metals in a reaction vessel in which the droplets move in countercurrent to a stream of hot gas in the presence of water vapour to form a particulate oxide compound product while the droplets and their decomposition products are in free fall in said stream. The product may be further heated, e.g. in a fluidized bed. In examples, (1) FeCl2 and ZnCl2 produce ZnO.Fe2O3, (3) FeCl2 and NiCl2 produce NiO.Fe2O3, (4) FeCl2 and BaCl2 produce BaO.6Fe2O3, (5) FeCl2 and BaCl2 produce BaFeO4.