Abstract: Phosphorous acid is made by a continuous recycling process from a mixture of phosphorous and hydrochloric acids, comprising:(i) continuously recycling the mixture in a loop apparatus;(ii) adding water to and passing phosphorus trichloride into said recycling mixture so as to generate a condition of turbulent flow at the point of contact of the phosphorus trichloride and the recycling mixture, whereby a reaction product, comprising an aqueous solution of phosphorous and hydrochloric acids as a continuous liquid phase and gaseous hydrogen chloride as gas bubbles of disperse phase, is produced;(iii) separating said gaseous hydrogen chloride;(iv) cooling said reaction product; and(v) recycling at least a portion of said reaction product and repeating steps (ii), (iii) and (iv) thereon to produce a more highly concentrated solution of phosphorus acid.

Abstract: Amorphous red phosphorus useful for matches, or as flame retardant is made by forming a slurry of 10-45% red phosphorus in molten white phosphorus, reducing the content of yellow phosphorus to less than 20% of the red phosphorus by separation at less than 280.degree. C., and then heating the product at above 295.degree. C. to convert, and preferably also evaporate, the white phosphorus.

Abstract: Phosphate rock can be heat treated at 380.degree.-600.degree. C. to convert the organics to filterable carbon and the rock converted to wet process phosphoric acid of reduced color and with reduced foaming. Rocks having high acid soluble organics but low total organics, and rocks containing a high content of acid insoluble heat labile iron sulphide are especially suitable.

Abstract: Wet process phosphoric acid is heated by passing alternating current through the acid, preferably in carbon apparatus to concentrations above 76% P.sub.2 O.sub.5 and preferably temperatures above 500.degree. C. to remove sulphate and fluoride and convert organic and basic impurities into a filterable precipitate; the acid is separated from the precipitate preferably after dilution with water to provide a high purity crystallizable product.

Abstract: Apparatus and method for preparing phosphorus compounds wherein phosphorus vapor containing P.sub.2 molecules is condensed at a temperature below the solidification point of red phosphorus and the resulting solid is then reacted with a phosphorus-reactive material. When the phosphorus-reactive material is water at an elevated temperature, phosphine is produced.

Abstract: Wet process phosphoric acid is heated, preferably in carbon apparatus, by passing alternating current through the acid, to concentrations above 80% P.sub.2 O.sub.5 and preferably temperatures above 500.degree. C. to remove sulphate and fluoride and convert organic and basic impurities into a filterable precipitate: the acid is separated from the precipitate to provide a high purity crystallizable product.