Alcan International Limited

Herbert F Askew

Stephen C Brown

John H Turner

Anthony R Emery

A paint or varnish composition is described which comprises a medium, such as an alkyd resin, and an anticorrosion agent which is environmentally non-hazardous and soluble or adapted to be soluble in the medium. The composition is suitable for application to a metal substrate and the anticorrosion agent is selected so as to enable a dry paint or varnish film to be obtained on the metal substrate, preferably within 24 hours from the time of application.

Surface coating compositions

A method of reducing the particle size of solid particles is applicable to the production of very fine particles of a wide variety of solids, including alumina hydrate, and comprises milling a liquid suspension of solid particles in an agitated media mill, pumping the milled suspension through a particle size classification device to separate the slurry into a coarse fraction and a fine fraction, the particles of the coarse fraction having a greater median particle size than the particles of the fine fraction, recycling the coarse fraction from the particle size classification device to the input of the mill, and recycling the fine fraction by pumping it to the classification device, wherein recycling of both coarse and fine fractions are continued until solid particles of the desired reduced particle size are produced. Preferably a single classification device and a single mill can be used, and particles having a median particle size of 0.3 microns or less and a relatively narrow paricle size distribution can be produced, even using a hydrocyclone as the classification device.

Method of producing fine particles

A method of reducing the particle size of solid particles is applicable to the production of very fine particles of a wide variety of solids, including alumina hydrate, and comprises milling a liquid suspension of solid particles in an agitated media mill, pumping the milled suspension through a particle size classification device to separate the slurry into a coarse fraction and a fine fraction, the particles of the coarse fraction having a greater median particle size than the particles of the fine fraction, recycling the coarse fraction from the particle size classification device to the input of the mill, and recyling the fine fraction by pumping it to the classification device, wherein recycling of both coarse and fine fractions are continued until solid particles of the desired reduced particle size are produced. Preferably a single classification device and a single mill can be used, and particles having a median particle size of 0.3 microns or less and a relatively narrow particle size distribution can be produced, even using a hydrocyclone as the classification device.

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Turville, United Kingdom

Herbert F Askew