Process for preparing wet process phosphoric acid stabilized against iron and aluminum precipitation

Claim 1

A PROCESS FOR PREPARING A "WET PROCESS" PHOSPHORIC ACID CONTAINING IRON AND ALUMINUM IMPURITIES, BUT STABILLIZED AGAINST PRECIPITATION OF SAID IRON AND ALUMINUM IMPURITIES COMPRISING: (A) CLARIFYING A CONCENTRATED CRUDE "WET PROCESS" PHOSPHORIC ACID HAVING A P2O5 LEVEL OF BETWEEN ABOUT 44 AND 59 WEIGHT PERCENT P2O5 WHICH CONTAINS IRON AND ALUMINUM IMPURITIES WHICH WOULD PRECIPITATE ON STANDING, (B) AND ADDING TO THE CRUDE "WET PROCESS" PHOSPHORIC ACID EITHER BEFORE OR AFTER CLARIFICATION, IN A QUANTITY OF BETWEEN ABOUT 0.20 AND 1.00 GRAM EQUIVALENT PER MOLE OF P2O5 IN THE SAID ACID, A COMPOUND SELECTED FROM THE CLASS CONSISTING OF AMMONIA, AMMONIUM HYDROXIDE, POTASSIUM HYDROXIDE, POTASSIUM CARBONATE, SODIUM HYDROXIDE, SODIUM CARBONATE, MAGNESIUM OXIDE, MAGNESIUM HYDROXIDE, AND MAGNESIUM CARBONATE, SAID ADDITION BEING IN AN AMOUNT SUFFICIENT TO STABILIZE THE "WET PROCESS" PHOSPHORIC ACID AGAINST PRECIPITATION OF IRON AND ALUMINUM IMPURITIES THEREFROM.