Inventors:
Ronald J. Smith - Friendswood TX
Manuel A. Gonzalez - Houston TX
Assignee:
Olin Corporation - New Haven CT
International Classification:
C01F 100, C01F 500, C01F 1100
Abstract:
An improved process is described for preparing defluorinated phosphate rock (DPR) granules from fluorine-containing phosphate rock. In particular, the improvement is useful in conventional processes which comprise the steps of:
(a) admixing fluorine-containing phosphate rock, phosphoric acid, sodium carbonate, and water to form a non-granulated feed slurry;
(b) forming granules in a granulating zone from said non-granulated feed slurry;
(c) drying said granules in a drying zone;
(d) classifying said dried granules to form a product fraction, an over-size fraction, and a fines fraction of said granules;
(e) crushing said over-size fraction and recycling said crushed over-size fraction, said fines fraction and 0-95% by weight of said product fraction back to step (b);
(f) heating the unrecycled product fraction to defluorinate said fluorine-containing phosphate rock contained therein without fusion;
(g) recovering said defluorinated phosphate rock granules;
the improvement which comprises
adding an aqueous solution to said granulation zone in a proportion equivalent to form about 5% to about 30% by volume of said non-granulated feed slurry, said aqueous solution being added only when more than about 20% by weight of dried granules discharged from said drying zone are less than about 20 mesh in size.