Method of producing phosphate fertilizers

Claim 1

IN A PROCESS OF MANUFACTURING A PHOSPHATE FERTILIZER IN WHICH NATURAL PHOSPHATE ROCK CONTAINING CALCIUM PHOSPHATE IS REACTED WITH NITRIC ACID AND THERE IS ADDED A NEUTRALIZING AGENT TO THE MIXTUE OF SAID PHOSPHATE ROCK AND NITRIC ACID, THE METHOD OF COMPLETELY NEUTRALIZING THE MIXTURE AND PREVENTING THE FORMATION IN THE REACTION PRODUCT OF SAID PHOSPHATE ROCK, NITRIC ACID AND NEUTRALIZING AGENT OF CALCIUM PHOSPHATE IN A FORM WHICH IS INSOLUBLE IN AMMONIUM CITRATE WHICH COMPRISES THE STEPS OF ADDING THE NEUTRALIZING AGENT TO SAID MIXTURE OF PHOSPHATE ROCK AND NITRIC ACID IN SUFFICIENT AMOUNT TO COMPLETELY NEUTRALIZE IT AND A COMPOUND OF ALUMINUM IN AN AMOUNT TO INSURE THE PRESENCE OF AT LEAST 20 MOLS OF A1 TO EACH 100 MOLS OF P2O5 PRESENT IN THE MIXTURE AND ADDING TO SAID MIXTURE A COMPOUND CONTAINING SULPHATE IONS TO ENSURE THE PRESENCE OF SULHATE IONS IN AN AMOUNT TO CONVERT ALL CALCIUM NITRATE PRESENT INTO CALCIUM SULHATE, SAID ALUMINUM COMPOUND BEING ADDED AFTER SAID ROCK PHOSPHATE IS REACTED WITH SAID ACID AND PRIOR TO THE ADDITION OF SAID NEUTRALIZING AGENT.