Interox Chemicals Limited

Denis A Hutton

Malcolm H Millar

Diana M Anderson

The scarcity of high grade tungsten ores obliges users to seek to recover it from scrap materials, but drill bits in particular pose especial problems. Existing proposals to use acidic hydrogen peroxide to oxides and solubilize tungsten is extremely inefficient in reagent consumption per unit tungsten recovered. According to the present invention, hydrogen peroxide can be used considerably more efficiently in the extraction of tungsten into an aqueous acidic solution by employing certain promoters which are solid at 50.degree. C. in the form of fused blocks. These blocks release the promoter slowly into the reaction solution and achieve similar efficiency of use of hydrogen peroxide and acid but at markedly reduced consumption of promoter in comparison with the same promoter added in powder or granular form. Examples of such promoter are hydroxy or amino substituted aromatic carboxylic acids e.g. 2-hydroxybenzoic acid. The promoters can most conveniently be used in a multi-stage tungsten extraction process.

Tungsten recovery

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.

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Sale, United Kingdom

Denis A Hutton