Clarification of concentrated wet process phosphoric acid

Claim 1

IN A PROCESS OF OBTAINING MINIMAL POST-PRECIPITATION OF CONCENTRATED WET PROCESS PHOSPHORIC ACID OF ABOUT 54% P2O5 AND CONTAINING FROM ABOUT 0.75% TO ABOUT 2.5% IRON BY WEIGHT AND FROM ABOUT 0.8% TO ABOUT 2.0% ALUMINUM BY WEIGHT, ALL IN THE FORM OF THEIR OXIDES, THE IMPROVEMENT WHICH COMPRISES THE STEPS OF: ADDING AT FROM ROOM TEMPERATURE TO ABOUT 180*F. FROM ABOUT 0.3% TO ABOUT 2% OF A SIMPLE, INORGANIC POTASSIUM SALT TO SAID CONCENTRATED PHOSPHORIC ACID OF ABOUT 54% P2O5, SAID SALT BEING SELECTED FROM THE GROUP CONSISTING OF POTASSIUM SULFATE, POTASSIUM NITRATE, POTASSIUM PHOSPHATE, POTASSIUM DIHYDROGEN PHOSPATE AND POTASSIUM CHLORIDE, AGING SAID MIXTURE FROM ABOUT TWO TO FOURTEEN DAYS, PRECIPITATING ALUMINUM AND IRON PHOSPHATE COMPLEXES, SEPARATING RESULTANT CLARIFIED CONCENTRATED WET PROCESS PHOSPHORIC ACID FROM SAID PRECIPITATED COMPLEXES, AND RECOVERING FOR STORAGE OR SHIPPING, THE SO-TREATED, SUBSTANTIALLY PRECIPITATE-FREE, CONCENTRATED WET PROCESS PHOSPHORIC ACID.