Albright & Wilson Limited

Thomas A Williams

Robert Harry Edwards

Douglas E Mather

Frank Michael Cussons

Kenneth Hall

Alexander Thomson

Wet process phosphoric acid is purified by extraction with a hexanone of pentanone to form an organic extract, containing phosphoric acid, from which the acid content is recovered by treatment with water or aqueous phosphoric acid in 2 or more portions to give 2 or more purified acids, the recovery to give the last purified acid being in more than 1 countercurrent stage.

Process for purifying phosphoric acid

In the manufacture of detergent powders containing alkoxylated alcohols, the problem arises that the alcohols cannot be spray-dried with the rest of the constituents. The invention provides a method of incorporating the alcohols into the spray-dried powder in such a way that staining of the packages does not occur. This is done by adding the alcohols in the form of a solution which combines with the residual water in the powder to form a gel.

Manufacture of detergents

When crude wet process phosphoric acid is solvent extracted, an aqueous raffinate containing phosphoric acid and a small amount of solvent is produced as a by-product. Certain materials are added to the raffinate, in order to produce two phases, one aqueous and the other of solvent. The phases are separated, the solvent recycled for reuse in a solvent extraction process and the aqueous phase treated with ammonia or alkali or alkaline earth metal compounds to form a fertilizer or other phosphate salt.

Process for removing solvent from the raffinate of extracted phosphoric

Wet process phosphoric acid may be purified by solvent extraction to produce a product of greater purity and concentration than has hitherto been attainable by employing an acyclic hexanone, preferably methyl isobutyl ketone as the solvent. Preferably the extraction of the acid into the ketone and the release into water are carried out in 2 actual or theoretical counter-current stages. Alternatively the release may be carried out into an aqueous solution of a base.

Purification of phosphoric acid by solvent extraction using hexanones

Phosphate values can be recovered from an organic extract which is formed by contact of wet process phosphoric acid and a water immiscible solvent, in a process in which the extract is treated with an inorganic base or a dihydrogen phosphate salt to give an acid free solvent and an aqueous solution of phosphoric acid and phosphate salt with a cation to P usually in the 0.1 - 0.5 : 1 region. The aqueous solution represents a concentrated soluble phosphate source for subsequent neutralization and conversion to e.g. tripolyphosphates.

Process for preparing phosphate salts

A solid anhydrous crystalline compound of the formula H.sub.3 PO.sub.4 [(CH.sub.3).sub.2 CH].sub.2 O. The invention also provides a method of preparing phosphoric acid by evaporating diisopropyl ether off said anhydrous crystalline compound under reduced pressure.

Ether phosphoric acid compound

In a process for preparing phosphoric acid by contact of sulphuric acid and phosphate rock with filtration of the gypsum slurry and recycle of the rest for contact with fresh rock, a fraction of the recycle slurry is treated with sulphuric acid to convert at least some of the gypsum to calcium sulphate hemihydrate and the slurry comprising hemihydrate is returned to contact the mixture of phosphate rock, phosphoric acid and recycle gypsum slurry. The process gives an easily filtered gypsum slurry with low phosphate losses in the gypsum filter cake.

Process for preparing phosphoric acid

Production of phosphoric acid by the wet process and by-product calcium sulphate hemihydrate. Sulphuric acid reacts with phosphate rock in such conditions that gypsum is precipitated, the resulting slurry is transferred to a second vessel in which the conditions are such that the gypsum recrystallises to calcium sulphate hemihydrate. Calcium sulphate hemihydrate so produced may be converted to cement and sulphuric acid by a process analogous to the anhydrite process for production of sulphuric acid. The phosphoric acid produced may be desulphated in a process integrated with the phosphoric production.

Manufacture of phosphoric acid

A solid anhydrous 1:1 molar compound of phosphoric acid and diisopropyl ether is prepared from a mixture of the ether and phosphoric acid in a molar ratio (R:1) of 0.6:1 to 1.4:1 at a temperature at least as low as the crystallization temperature (T.degree.C) governed by the relationship T = 25(1.2-R). Treatment of the compound with water or a base produces purified acid or a phosphate respectively.

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Beckermet, United Kingdom

Thomas A Williams