Process for preparing anhydrous polyphosphate mixed alkali metal salts
AssigneeMonsanto Company
InventorsLouis A. Highfill, George D. Rozelle
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Abstract
There is disclosed a process for preparing mixed alkali metal salts of tripolyphosphate. A solution of mixed orthophosphate salts, such as sodium and potassium is dried by spraying the mixture onto a hot tumbling bed of a mixture of phosphate salts. The dried salts are then calcined at a temperature in the range of from about 350.degree. C. to about 600.degree. C., preferably above 500.degree. C. to form the mixed alkali metal salt of tripolyphosphate.
Claims11
A process for preparing a mixed alkali metal polyphosphate salts which comprises the steps of:
- a. preparing a solution of a mixture of alkali metal orthophosphate salts;
- b drying said salt solution by spraying the solution onto a hot tumbling bed of a mixture of phosphate salts, and;
- c. calcining the dried salt mixture at a temperature in the range of from about 400.degree. C. to about 600.degree. C. to form a mixed alkali metal polyphosphate salts containing a major amount of tripolyphosphate, said salts comprising a crystalline, solid solution having an M.sub.2 O/P.sub.2 O.sub.5 ratio less than 2 and greater than 1.5 wherein M.sub.2 O is a mixture of Na.sub.2 O and K.sub.2 O in a molar ratio of 3:2 respectively.
A process for preparing a mixed sodium potassium tripolyphosphate salts which comprises the steps of:
- a. preparing a solution of a mixture of sodium and potassium orthophosphate salts;
- b. drying said salt solution by spraying the solution onto a tumbling bed of mixture of sodium and potassium phosphate salts, and;
- c. calcining the dried salt mixture at a temperature in the range of from about 350.degree. C. to about 600.degree. C. to form a crystalline solid solution of trisodium dipotassium tripolyphosphate having an M.sub.2 O/P.sub.2 O.sub.5 ratio in the range of less than 2 and greater than 1.5 wherein the M.sub.2 O represents the mixture of Na.sub.2 O and K.sub.2 O in a molar ratio of 3:2 respectively.
Dependencies are inferred from the claim text.