Occidental Research Corporation

Occidental Chemical Agricultural Products, Inc.

Gary L Beer

Elie M Chemtob

Alkali metal phosphates and HF can be produced from a substantially calcium-free fluoroaluminum phosphate precipitate (which also contains iron) made by the aging of wet process phosphoric acid containing iron, fluorine and aluminum, preferably phosphoric acid analyzing in the range of about 15%-45 weight percent P.sub.2 O.sub.5, 2-4% Al.sub.2 O.sub.3 and 1-2% fluorine. One process involves digestion of phosphate ore matrix in recycled phosphoric acid, filtration to remove the insoluble residue, precipitation and filtration to remove gypsum, and aging of the product acid to precipitate the aluminum impurity as a fluoroaluminum phosphate compound. The fluoroaluminum phosphate can be decomposed (as by heating at above 195.degree. C.) to produce HF and aluminum phosphate. The aluminum phosphate can be contacted with alkali metal hydroxide under conditions which produce an alkali metal phosphate.

Aluminum fluorophosphates made from impure phosphoric acids and

Substantially calcium-free fluoroaluminum phosphate precipitate (which also contains iron) can be produced by the aging of wet process phosphoric acid containing iron, fluorine and aluminum, preferably phosphoric acid analyzing in the range of about 15%-45 weight percent P.sub.2 O.sub.5, 2-4% Al.sub.2 O.sub.3 and 1-2% fluorine. One process involves digestion of phosphate ore matrix in recycled phosphoric acid, filtration to remove the insoluble residue, precipitation and filtration to remove gypsum, and aging of the product acid to precipitate the aluminum impurity as a fluoroaluminum phosphate compound. The fluoroaluminum phosphate can be decomposed (as by heating at about 195.degree. C.) to produce HF and aluminum phosphate.

Process for producing HF from impure phosphoric acids

Aluminum fluorophosphate can be produced by the aging of phosphoric acid containing fluorine and aluminum, preferably phosphoric acid analyzing in the range of about 15-45 weight percent P.sub.2 O.sub.5, 2-4% Al.sub.2 O.sub.3 and 1-2% fluorine. One process involves digestion of phosphate ore matrix in recycled phosphoric acid, filtration of the insoluble residue, precipitation and filtration of gypsum, and aging of the product acid to precipitate the aluminum impurity as an aluminum fluorophosphate compound. The aluminum fluorophosphate can be decomposed (as by heating at about 195.degree. C.) to produce HF and aluminum phosphate.

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Huntington Beach, CA, United States of America

Gary L Beer