Process for defluorinating phosphatic materials

Claim 1

METHOD FOR PREPARING PHOSPHATIC MATERIALS HAVING FLOURINE CONTENTS WHEREBY THE MATERIALS ARE SUITABLE FOR USE AS ANIMAL FEEDS, COMPRISING ADDING TO CRUDE WET PROCESS PHOSPHORIC ACID CONTAINING AT LEAST 20% PHOSPHORIC ACID, AS P2O5, AN AMOUNT OF SODIUM CARBONATE SUFFICIENT TO PRECIPITATE SUBSTANTIALLY ALL OF THE FLUORINE PRESENT IN SAID ACID, REMOVING THE PRECIPITATE FROM SAID ACID AS A FIRST PRECIPITATE, ADDING TO SAID ACID FROM WHICH SAID FIRST PRECIPITATE HAS BEEN REMOVED A QUANITY OF LIME SUFFICIENT TO PRECIPITATE NOT OVER 20% OF THE PHOSPHORUS OF SAID ACID, REMOVING THE PRECIPITATE FROM SAID ACID AS A SECOND PRECIPITATE, SAID ACID FROM WHICH SAID SECOND PRECIPITATE HAS BEEN REMOVED CONTAINING ONLY TRACES OF RESIDUAL FLUORINE, SAID SECOND PRECIPITATE CONTAINING SUBSTANTIAL AMOUNTS OF FLUORINE AND PHOSPHORIC ACID, ADDING TO SAID SECOND PRECIPITATE GYPSUM IN AMOUNT SUFFICIENT TO REDUCE THE P2O5 CONTENT THEREOF, AFTER CALCINATION, TO BETWEEN 13% AND 22% P2O5, AND CALCINING SAID SECOND PRECIPITATE MIXTURE AT A TEMPERATURE BETWEEN 1500*F. AND 3000*F. AND BELOW THE FUSING TEMPERATURE OF THE MIXTURE UNTIL SUBSTANTIALLY ALL OF THE FLUORINE CONTENT THEREOF IS DISPELLED.