Defluorination of phosphate rock

Claim 1

THE METHOD OF DEFLUORINATING A PHOSPHATE ROCK CONTAINING SILICA AND AT LEAST 3% FLUORINE WHICH COMPRISES MIXING THE ROCK WITH FROM 10 TO 25% BY WEIGHT OF ROCK AND ACID, CALCINING THE COMBINED WEIGHT OF ROCK AND ACID, CALCINING THE RESULTING MIXTURE IN AN ATMOSPHERIC OF WATER VAPOR AT A TEMPERATURE BETWEEN 1800 AND 2600* F. AND THEREBY REMOVING AT LEAST HALF OF THE FLUORINE ORIGNINALLY CONTAINED IN THE ROCK, GRINDING AND MIXING WITH THE RESULTING CALCINE AND AMOUNT OF LIME THEORETICALLY REQUIRED, WITH THE LIME ALREADY PRESENT, TO FORM TRICALCIUM PHOSPHATE WITH ALL THE PHOSPHORUS PENTOXIDE PRESENT IN THE CALCINE, AND WITH A SUFFICIENT EXCESS OF LIME THEORETICALLY REQUIRED TO COMBINED WITH THE SILICA PRESENT IN THE CALCINE TO FORM DICALCIUM SILICATE, AND CALCINING THE MIXTURE OF CALCINE AND LIME AT A TEMPERATURE EXCEEDING THAT OF THE FIRST CALCINING STEP AND OF AT LEAST 2400* F. BUT NOT TOO HIGH TO CAUSE FUSION OF THE MIXTURE AND THEREBY PRODUCING A PHOSPHATE PRODUCT HAVING A P2O5 CONTENT OF AT LEAST 35% AND CONTAINING LESS THAN 0.2% FLUORINE AND OF HIGH FERTILLIZER AVAILABILITY.

Claim 2

THE METHOD OF DEFLUORINATING A PHOSPHATE ROCK CONTAINING SILICA AND AT LEAST 3% FLUORINE WHICH COMPRISES MIXING THE ROCK WITH FROM 10 TO 25% BY WEIGHT OF ROCK AND ACID, CALCINING THE COMBINED WEIGHT OF ROCK AND ACID, CALCINING THE RESULTING MIXTURE IN AN ATMOSPHERIC OF WATER VAPOR AT A TEMPERATURE BETWEEN 1800 AND 2600* F. AND THEREBY REMOVING AT LEAST HALF OF THE FLUORINE ORIGNINALLY CONTAINED IN THE ROCK, GRINDING AND MIXING WITH THE RESULTING CALCINE AND AMOUNT OF LIME THEORETICALLY REQUIRED, WITH THE LIME ALREADY PRESENT, TO FORM TRICALCIUM PHOSPHATE WITH ALL THE PHOSPHORUS PENTOXIDE PRESENT IN THE CALCINE, AND WITH A SUFFICIENT EXCESS OF LIME THEORETICALLY REQUIRED TO COMBINED WITH THE SILICA PRESENT IN THE CALCINE TO FORM DICALCIUM SILICATE, AND CALCINING THE MIXTURE OF CALCINE AND LIME AT A TEMPERATURE EXCEEDING THAT OF THE FIRST CALCINING STEP AND OF AT LEAST 2400* F. BUT NOT TOO HIGH TO CAUSE FUSION OF THE MIXTURE AND THEREBY PRODUCING A PHOSPHATE PRODUCT HAVING A P2O5 CONTENT OF AT LEAST 35% AND CONTAINING LESS THAN 0.2% FLUORINE AND OF HIGH FERTILLIZER AVAILABILITY.