PHOSPHOGYPSUM TREATMENT PROCESS

WIPO Patent Application WO2005118222

A3

A method of treating phosphogypsum produces calcium carbonate and ammonium sulfate from the phosphogypsum. The calcium carbonate contains impurities from the phosphogypsum. The calcium carbonate is reacted with an organic acid to produce a liquid calcium salt of the organic acid and un-reacted solid impurities. The calcium salt of the organic acid is consumed through at least one of two processes. First, the calcium salt of the organic acid may be reacted with phosphoric acid to produce calcium phosphate. Second, the calcium salt of the organic acid may be reacted with the ammonium sulfate to produce the ammonium salt of the organic acid and gypsum, the ammonium salt of the organic acid being reacted with the phosphoric acid to produce ammonium phosphate. The gypsum produced in the second process may have a reduced impurity level relative to phosphogypsum. An integrated process for producing feed grade phosphates while substantially reducing the amount of gypsum waster generated by the production of impure phosphogypsum and impure phosphoric acid from phosphate rock is also disclosed.

MENG XIANGSHENG (US)
PEACOCK LAWRENCE A (US)
TSOBANAKIS PARASKEVAS (US)
OLSON RONALD E (US)
CLARK DONALD R (US)
SANDERSON CHARLES (US)

PCT/US2005/018980

July 20, 2006

May 31, 2005

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CARGILL INC (US)
MENG XIANGSHENG (US)
PEACOCK LAWRENCE A (US)
TSOBANAKIS PARASKEVAS (US)
OLSON RONALD E (US)
CLARK DONALD R (US)
SANDERSON CHARLES (US)

C01B25/32; B24D3/02; C01B25/28; C01C1/02; C01C1/24; C01C1/244; C01F11/46

US4328189A	1982-05-04
US3951675A	1976-04-20

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