Method of producing concentrated phosphoric acid

Claim 1

The method of claim 1 wherein for each part by weight of the salt, there is present an amount of methanol in the range 0.8 to 10 parts, and the mixture contains in parts by weight less than 50- 60 parts of water per 100 parts of metHanol.

Claim 3

A method for the production of concentrated phosphoric acid which comprises reacting monocalcium phosphate with a sulfate acid by mixing the reactants and methanol while maintaining the temperature of the mixture in the range from about 15* to 50* C. for a period in the range from about 1 minute to 10 hours, wherein for each mol of the phosphate salt the amount of acid is in the range from about 1.8 to 2.4 equivalents, wherein for each part by weight of the salt, there is present an amount of methanol in the range from about 0.8 to 3 parts, wherein said acid is selected from the group consisting of sulfuric acid, ammonium bisulfate and mixtures thereof, and wherein said mixture contains in parts by weight less than about 5 parts by weight of water per 100 parts of methanol; physically separating the resulting reaction mixture into a liquid fraction and a solid fraction; and removing methanol from the liquid fraction by fractional distillation; the liquid present in said reaction mixture constituting substantially the total amount of liquid employed in said method of producing concentrated phosphoric acid.

Claim 5

The method of producing an inorganic phosphate salt which comprises reacting monocalcium phosphate with a sulfate acid by mixing the reactants and methanol while maintaining the temperature of the mixture in the range below the boiling point of methanol and above about 0* C. for a period in the range from about 1 minute to 10 hours, wherein for each mol of the phosphate salt the amount of acid is in the range of 0.5 to 2.0 times the metathetical requirement, and wherein said acid is selected from the group consisting of sulfuric acid, ammonium bisulfate and mixtures thereof; physically separating the resulting reaction mixture into a liquid fraction of phosphoric acid dissolved in methanol and a solid fraction; and then precipitating an inorganic phosphate salt selected from the group consisting of ammonium phosphate, alkali metal phosphates and alkaline earth metal phosphates from the liquid fraction of phosphoric acid dissolved in methanol by adding a base having a corresponding cation to said liquid fraction; the liquid present in said reaction mixture and said base constituting substantially the total amount of liquid employed in said method of producing an inorganic phosphate salt.

Claim 6

The method of producing an inorganic phosphate salt which comprises reacting monocalcium phosphate with a sulfate acid by mixing the reactants and methanol while maintaining the temperature of the mixture in the range from about 15* to 50* C. for a period in the range from about 1 minute to 10 hours, wherein for each mol of the phosphate salt the amount of acid is in the range from about 1.8 to 2.4 equivalents, wherein for each part by weight of the salt, there is present an amount of methanol in the range from about 0.8 to 3 parts, wherein said acid is selected from the group consisting of sulfuric acid, ammonium bisulfate and mixtures thereof, and Wherein said mixture contains in parts by weight less than about 5 parts by weight of water per 100 parts of methanol; physically separating the resulting reaction mixture into a liquid fraction and a solid fraction; and then precipitating an inorganic phosphate salt selected from the group consisting of ammonium phosphate, alkali metal phosphates and alkaline earth metal phosphates from the liquid fraction of phosphoric acid dissolved in methanol by adding a base having a corresponding cation to said liquid fraction; the liquid present in said reaction mixture and said base constituting substantially the total amount of liquid employed in said method of producing an inorganic phosphate salt.