Chemistry: fertilizers – Processes and products – Inorganic material
Patent
1978-08-02
1979-07-10
Vertiz, O. R.
Chemistry: fertilizers
Processes and products
Inorganic material
71DIG3, 423158, 423167, 423309, 423319, C05B 1110
Patent
active
041606574
ABSTRACT:
Monocalcium phosphate, phosphoric acid and/or potassium phosphate containing fertilizers are produced in a process involving acidulation of phosphate rock with phophoric acid in the presence of added silicon dioxide and potassium ion whereby fluorides contained in the rock are converted to K.sub.2 SiF.sub.6, wherein monocalcium phosphate dissolved in phosphoric acid is formed during acidulation. In an important feature, the K.sub.2 SiF.sub.6 is separated and hydrolyzed to regenerate the K.sub.2 O from K.sub.2 SiF.sub.6 as recycled KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solution for further reaction with fluoride from fresh phosphate rock feed. A portion of the MCP/H.sub.3 PO.sub.4 solution and/or crystallized monocalcium phosphate can then be reacted with potassium sulfate, potassium bisulfate, or mixtures thereof, to form KH.sub.2 PO.sub.4, or KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solutions, and gypsum. In a closely related embodiment, the remaining MCP/H.sub.3 PO.sub.4 solution is reacted with sulfuric acid to produce phosphoric acid product and/or the recycle phosphoric acid required in the phosphate rock acidulation step.
REFERENCES:
patent: 3110562 (1963-11-01), Hinkle, Jr.
patent: 3512927 (1970-05-01), Betts
patent: 3554694 (1971-01-01), Barker et al.
patent: 3792151 (1974-02-01), Case
patent: 3795728 (1974-03-01), Scheel
patent: 3840640 (1974-10-01), Drechsel
patent: 4086322 (1978-04-01), Drechsel
"Fluorine Recovery from Phosphate Rock Concentrates," Bureau of Mines Report of Investigations/1977.
Drechsel, "Phosphate Conversion-- A New Perspective," paper presented to the American Chemical Society (Sep. 1, 1976).
Langel Wayne A.
Pennzoil Company
Vertiz O. R.
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