Defluorination of phosphate rocks

Claim 1

THE IMPROVEMENT IN DEFLUORINATING PHOSPHATE ROCK AND INCREASING ITS FERTILIZER AVAILABILITY WHICH COMPRISES FORMING A MIXTURE OF PHOSPHATE ROCK AND PHOSPHORIC ACID IN SUCH RELATIVE AMOUNTS AS TO PRODUCE A MIXTURE INCAPABLE OF BEING CALCINED AT A TEMPERATURE OF 2500* F. WITHOUT SUBSTANTIAL FUSION, PROGRESSIVELY MOVING THE MIXTURE THROUGH A KILN FROM ONE END THEREOF IN THE PRESENCE OF WATER VAPOR AND PROGRESSIVELY RAISING THE TEMPERATURE THEREOF TO AT LEAST 2500* F., ADDING LIME TO THE PROGRESSIVELY-MOVING MIXTURE IN AMOUNT SUFFICIENT TO RAISE THE FUSION POINT OF THE MIXTURE TO A TEMPERATURE ABOVE 2500* F., SAID LIME BEING ADDED BY BLOWING IT IN FINELY-DIVIDED FORM INTO THE OTHER END OF KILN, WHEREBY LIME IS DEPOSITED ONTO AND RETAINED BY THE MIXTURE IN PROGRESSIVELY LESS AMOUNTS TOWARDS SAID FIRST-MENTIONED END OF THE KILN, AND CAUSING THE MIXTURE TO MOVE THROUGH THE KILN AT A RATE SUCH THAT FLUORINE IS SUBSTANTIALLY LIBERATED BEFORE THE AMOUNT OF LIME TAKEN UP BY THE MIXTURE IS SUFFICIENT TO OBJECTIONABLY IMPEDE FLUORINE ELIMINATION.