Alcan International Limited

Alfa Biotech S.p.a.

Jean V Sang

Robert Edward Burrell

Olivo G Sivilotti

Paul Groves

Rejean J Lemay

Carson J Ogilvie

Gerard Flynn

Magnetically attractable particles comprise a core of magnetic material encapsulated in a metal oxide coating. They may be made by emulsifying an aqueous solution or dispersion of the magnetic material or precursor, and an aqueous solution or sol of a coating inorganic oxide or precursor, in an inert water-immiscible liquid. The aqueous droplets are gelled, e.g. by ammonia or an amine, recovered, and heated at 250.degree.-2000.degree. C. The resulting particles are generally smooth spheres below 100 microns in diameter and often of sub-micron size.

Magnetically attractable particles and method

In a process for producing anhydrous magnesium chloride, the following combination of steps: drying impure salt containing hydrated magnesium chloride; establishing a solution of the hydrated magnesium chloride; removing insoluble impurities; reacting the solution of hydrated magnesium chloride at substantially ambient temperature and pressure by feeding it into an ammonia saturated very low boiling point alcohol solution and in the presence of ammonium chloride while maintaining the last-mentioned solution saturated in ammonia thereby to form a precipitate of ammoniated magnesium chloride; separating the precipitate and heating it to obtain anhydrous MgCl.sub.2 and ammonia for recycling.

Process for making anhydrous magnesium chloride

The invention provides new processes for the production of precursor powders for ceramic materials by emulsion precipitation, the new processes permitting the economic production with at least some cations of uniformly small size particles (1 micrometer or less) to result in corresponding dense microstructures upon sintering the precursor powder to produce the ceramic material. The processes require the production of a fine water-in-oil type emulsion of an aqueous solution of the desired cation or cations in a non-miscible liquid, usually an oil, such as a saturated hydrocarbon, a suitable surfactant usually also being employed, The emulsion preferably has an aqueous particle size of 0.1 micrometer or less, produced by a mechanical emulsator. A gaseous reactant, preferably ammonia, or a mixture of ammonia with a neutral diluent gas, is bubbled through the emulsion to contact it and react with the cations, without breaking the emulsion by physical and/or chemical action. The emulsion becomes alkaline and may gell if the aqueous content is sufficiently high. Upon removal of the water and the non-miscible liquid, by heating, spray drying, freezing, etc., the particles that remain are found to have retained their fine structure without agglomerating. If one or more of the cations is of the type that forms complexes with ammonia it may be preferred to instead use a non-complexing gaseous reactant, such as carbon dioxide.

Production of ceramic powders by emulsion precipitation processes and

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Kingston, Canada

Jean V Sang