Production of feed grade dicalcium phosphate

Claim 1

A METHOD OF PRODUCING FEED GRADE DICALCIUM PHOSPHATE WHICH COMPRISES ACIDULATING A FLUORINE-CONTAINING PHOSPHATE ROCK WITH A MIXTUR OF SULFURIC AND PHOSPHORIC ACIDS TO FORM SUPERPHOSPHATE, HYDROLYZING THE SUPERPHOSPHATE WITH A LIMITED EXCESS OF WATER TO FORM A HYDROLYSIS PRODUCT COMPRISING A FLUORINE-CONTAINING SOLID AND DICALCIUM PHOSPHATE AND A PHOSPHATE-CONTAINING SOLUTION, THE RATIO OF P2O5 TO F IN SAID HYDROLYSIS PRODUCT BEING LESS THAN IN THE PHOSPHATE ROCK, SEPARATING THE HYDROLYSIS PRODUCT FROM THE SOLUTION, RAISING THE PH OF SAID SEPARATED SOLUTION TO BETWEEN ABOUT 4 AND 5 BY ADDING A LIME BASE TO THE SEPARATED SOLUTION OT PRECIPITATE A FEED GRADE DICALCIUM PHOSPHATE; REPULPING THE SOLID RESIDUE FORMED IN THE HYDROLYSIS OPERATION WITH DILUTE SULFURIC ACID TO DISSOLVE THE DICALCIUM PHOSPHATE CONTENT, SEPARATING THE SOLUTION FROM UNDISSOLVED SOLIDS, ADMIXING THE SEPARATED SOLUTION WITH SULFURIC ACID FOR USE IN THE INITIAL ACIDULATION OF PHOSPHATE ROCK; WASHING THE SAID UNDISSOLVED SOLIDS AND UTILIZING THE WASH WATER AS A DILUENT FOR CONCENTRATED SULFURIC ACID TO FORM THE DILUTE ACID FOR REPULPING THE HYDROLYSIS RESIDUE.

Claim 2

A METHOD OF PRODUCING FEED GRADE DICALCIUM PHOSPHATE WHICH COMPRISES ACIDULATING A FLUORINE-CONTAINING PHOSPHATE ROCK WITH A MIXTUR OF SULFURIC AND PHOSPHORIC ACIDS TO FORM SUPERPHOSPHATE, HYDROLYZING THE SUPERPHOSPHATE WITH A LIMITED EXCESS OF WATER TO FORM A HYDROLYSIS PRODUCT COMPRISING A FLUORINE-CONTAINING SOLID AND DICALCIUM PHOSPHATE AND A PHOSPHATE-CONTAINING SOLUTION, THE RATIO OF P2O5 TO F IN SAID HYDROLYSIS PRODUCT BEING LESS THAN IN THE PHOSPHATE ROCK, SEPARATING THE HYDROLYSIS PRODUCT FROM THE SOLUTION, RAISING THE PH OF SAID SEPARATED SOLUTION TO BETWEEN ABOUT 4 AND 5 BY ADDING A LIME BASE TO THE SEPARATED SOLUTION OT PRECIPITATE A FEED GRADE DICALCIUM PHOSPHATE; REPULPING THE SOLID RESIDUE FORMED IN THE HYDROLYSIS OPERATION WITH DILUTE SULFURIC ACID TO DISSOLVE THE DICALCIUM PHOSPHATE CONTENT, SEPARATING THE SOLUTION FROM UNDISSOLVED SOLIDS, ADMIXING THE SEPARATED SOLUTION WITH SULFURIC ACID FOR USE IN THE INITIAL ACIDULATION OF PHOSPHATE ROCK; WASHING THE SAID UNDISSOLVED SOLIDS AND UTILIZING THE WASH WATER AS A DILUENT FOR CONCENTRATED SULFURIC ACID TO FORM THE DILUTE ACID FOR REPULPING THE HYDROLYSIS RESIDUE.