Interox Chemicals Limited

Malcolm H Millar

Denis A Hutton

Gareth W Morris

Francis R Hardy

Douglas P Haughey

John R Crampton

Purification of hydrogen peroxide

Granules of magnesium salts are obtained by spraying onto agitated feed particles of the salt a small amount of a dilute aqueous solution of a synthetic poly hydroxy-substituted compound, such as polyvinylalcohol, and drying the resultant agglomerate. It is especially suitable to carry out the granulation process in a warm air fluidized bed using feed particles of mainly below 200 microns producing eventually a low bulk density product mainly in the range 200-100 microns. The granular salts have a particle size of from 0.15 to 1.0 mm and a free-flowing bulk density of from 0.3 to 0.6 kg/l.

Granular magnesium salts

Granules of the magnesium salts of percarboxylic acid carboxylates are obtained by spraying onto agitated feed particles of the salt a small amount of a dilute aqueous solution of a synthetic poly hydroxy-substituted compound, particularly polyvinylalcohol and drying the resultant agglomerate. It is especially suitable to carry out the granulation process in a warm air fluidized bed using feed particles of mainly below 200 microns producing eventually a low bulk density product mainly in the range 200-1000 microns. In a modification of the fluidized bed process, the agglomerating agent used can be a aqueous solution of carboxylated polyvinyl alcohol.

Granulation

Alkali metal or alkaline earth metal peroxides, for example, particularly, calcium peroxide, are produced by recovering a moist peroxide product from an aqueous mixture, formed by reacting hydrogen peroxide and a hydroxide or oxide of the alkali metal or alkaline earth metal, and drying the moist product by means of a pneumatic conveyer drier. The peroxide so produced is suitable for granulation. Alternatively, particulate substances, such as seed, are coated with the peroxide by blending with the moist peroxide product and passing the blend through the pneumatic conveyer drier.

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Widnes, United Kingdom

Malcolm H Millar