Anhydrous liquid phosphoric acid

Claim 1

A SUBSTANTIALLY ANHYDROUS LIQUID PHOSPHORIC ACID DERIVED FROM DILUTE WET-PROCESS PHOSPHORIC ACID WHICH CONTAINS INCIDENTAL METALLIC IMPURITIES COMPRISING IRON AND ALUMINUM; SAID ANHYDROUS LIQUID PHOSPHORIC ACID (1) CONTAINING BETWEEN ABOUT 1 AND ABOUT 10 WEIGHT PERCENT OF SAID METALLIC IMPURITIES (EXPRESSED AS OXIDES); (2) CONTAINING BETWEEN ABOUT 69 AND ABOUT 79 WEIGHT PERCENT PHOSPHORUS (EXPRESSED AS P2O5 ON A IMPURITY FREE BASIS), SAID PHOSPHORUS BEING PRESENT AS AN EQUILIBRATED MIXTURE OF ORTHOPHOSPHORIC AND ACYLIC POLYPHOSPHORIC ACID; (3) CONTAINING SAID ACYLIC POLYPHOSPHORIC ACID IN AN EFFECTIVE AMOUNT SUFFICIENT TO PREVENT THE FORMATION OF INSOLUBLE SALTS OF SAID IMPURITIES SO THAT SAID ACID WHEN NEUTRALIZED WITH AMMONIA TO A PH BETWEEN ABOUT 5.5 AND 10.0 AND DILUTED WITH WATER WILL FORM A CLEAR AQUEOUS SOLUTION OF AMMONIUM PHOSPHATE FREE OF PRECIPITATES OF SAID METALLIC IMPURITIES; AND (4) SAID PHOSPHORIC ACID BEING FREE OF INSOLUBLE METAPHOSPHATE SALTS OF SAID METALLIC IMPURITIES.

Claim 3

THE METHOD OF TREATING WET PROCESS PHOSPHORIC ACID CONTAINING NORMALLY INCIDENT IMPURITIES COMPRISING IRON, ALUMINUM AND MAGNESIUM THAT COMPRISES: (1) HEATING SAID ACID AT ATMOSPHERIC PRESSURE TO A TEMPERATURE ABOVE ABOUT 120*C. WHILE REMOVING THE GASEOUS PRODUCTS VOLATILIZED THEREFROM TO THEREBY CONCENTRATE SAID ACID; (2) CONTINUING SAID HEATNG AND CONCENTRATING OF SAID ACID UNITL THE BULK CONCENTRATION OF SAID ACID IS AT LEAST 65 PERCENT P2O5 AND UNTIL SAID ACID WHEN NEUTRALIZED WITH AMMONIA TO A PH VALUE BETWEEN ABOUT 5.5 AND ABOUT 10.0 AND DILUTED WITH WATER WILL FORM A CLEAR, AQUEOUS SOLUTION OF AMMONIUM PHOSPHATE FREE OF PRECIPITATES OF SAID IMPURITIES; AND (3) THEREAFTER DISCONTINUING SAID HEATING AND RECOVERING AN IMPROVED WET PROCESS PHOSPHORIC ACID OF HIGH CONCENTRATION.

Claim 4

THE METHOD OF TREATING WET PROCESS PHOSPHORIC ACID CONTAINING NORMALLY INCIDENT IMPURITIES COMPRISING IRON, ALUMINUM AND MAGNESIUM THAT COMPRISES: (1) HEATING SAID ACID AT ATMOSPHERIC PRESSURE TO A TEMPERATURE ABOVE ABOUT 120*C. WHILE REMOVING THE GASEOUS PRODUCTS VOLATILIZED THEREFROM TO THEREBY CONCENTRATE SAID ACID; (2) CONTINUING SAID HEATNG AND CONCENTRATING OF SAID ACID UNITL THE BULK CONCENTRATION OF SAID ACID IS AT LEAST 65 PERCENT P2O5 AND UNTIL SAID ACID WHEN NEUTRALIZED WITH AMMONIA TO A PH VALUE BETWEEN ABOUT 5.5 AND ABOUT 10.0 AND DILUTED WITH WATER WILL FORM A CLEAR, AQUEOUS SOLUTION OF AMMONIUM PHOSPHATE FREE OF PRECIPITATES OF SAID IMPURITIES; AND (3) THEREAFTER DISCONTINUING SAID HEATING AND RECOVERING AN IMPROVED WET PROCESS PHOSPHORIC ACID OF HIGH CONCENTRATION.