US4008314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of solid ammonium phosphate
Assignee: Scottish Agricultural Industries Ltd
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Filing: 1976-01-20
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Granted: 1977-02-15
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Expires: 1996-01-20
Abstract
Abstract The invention relates to a process for the manufacture of solid monammonium phosphate in a suitable form for use as an ingredient in the granulation of NPK compound fertilizers. It has been found that some wet-process phosphoric acids used in the manufacture of fertilizer grade ammonium phosphate contain impurities in amounts and/or ratios which can give rise to hard oversize product in known methods of manufacture with the result that extra milling of the product is required. The process of the invention overcomes the need for extra milling by providing an improved product form. The improvement is achieved by mixing separately at one stage in a process of the kind described between 15% and 85% by volume of the total secondary acid feed with the aqueous ammonium phosphate slurry and adding the remainder of the secondary acid to the treated slurry at a later stage.
Inventors
- 👤 Eric Davidson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:08
CPC Classifications
C; C05; C05B; C05B7/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
209 words
A process for the production of a particulate solid product comprising ammonium phosphate of N:P atomic ratio 0.95 to 1.10 wherein a primary phosphoric acid-containing feed and ammonia are added to an aqueous slurry of ammonium phosphate of flowable consistency at the temperature of working and having an N:P atomic ratio of between 1.3 and 1.5 to form more slurry of substantially the same composition and concentration and flowable consistency, removing an amount of said slurry substantially equivalent to that produced by the addition of the phosphoric acid and ammonia and thereafter mixing the removed slurry with a secondary acid feed to reduce the N:P ratio to 0.95 to 1.10, wherein the removed slurry is first mixed separately with between 15% and 85% by volume of the secondary acid feed, followed by the addition of the remainder of the secondary acid at a later stage, so that the ammonium phosphate of the resulting product has an N:P atomic ratio in the range 0.95 to 1.10, the water contents of the removed aqueous slurry and the secondary acid feed being such that the resulting product solidifies in a moisture disengagement unit where it is treated for a sufficient period of time for said product to be solid at ambient temperature.
Claim 2
Dependent Claim
209 words
A process for the production of a particulate solid product comprising ammonium phosphate of N:P atomic ratio 0.95 to 1.10 wherein a primary phosphoric acid-containing feed and ammonia are added to an aqueous slurry of ammonium phosphate of flowable consistency at the temperature of working and having an N:P atomic ratio of between 1.3 and 1.5 to form more slurry of substantially the same composition and concentration and flowable consistency, removing an amount of said slurry substantially equivalent to that produced by the addition of the phosphoric acid and ammonia and thereafter mixing the removed slurry with a secondary acid feed to reduce the N:P ratio to 0.95 to 1.10, wherein the removed slurry is first mixed separately with between 15% and 85% by volume of the secondary acid feed, followed by the addition of the remainder of the secondary acid at a later stage, so that the ammonium phosphate of the resulting product has an N:P atomic ratio in the range 0.95 to 1.10, the water contents of the removed aqueous slurry and the secondary acid feed being such that the resulting product solidifies in a moisture disengagement unit where it is treated for a sufficient period of time for said product to be solid at ambient temperature.
Claim 3
Dependent Claim
23 words
A process as claimed in claim 1, wherein the remainder of the secondary acid feed is fed directly to the moisture disengagement unit.
Claim 4
Dependent Claim
33 words
A process as claimed in claim 1, wherein the remainder of the secondary acid feed is mixed with the removed slurry/secondary acid feed mixture, and fed together therewith to the moisture disengagement unit.
Claim 5
Dependent Claim
29 words
A process as claimed in claim 1, wherein the secondary acid feed is a mineral acid selected from the group consisting of phosphoric acid, sulphuric acid and mixtures thereof.
Claim 6
Dependent Claim
15 words
A process as claimed in claim 4, wherein the phosphoric acid is wet-process phosphoric acid.
Claim 7
Dependent Claim
15 words
A process as claimed in claim 1, wherein the secondary acid feed is partially ammoniated.
Claim 8
Dependent Claim
19 words
A process as claimed in claim 1, wherein a part of the solid end-product is recycled to the process.
Claim 9
Dependent Claim
187 words
A process for producing a particulate solid product comprising ammonium phosphate of N:P atomic ratio in the range 0.95 to 1.10 is performed by mixing "wet-process" phosphoric acid of P 2 O 5 content in the range 30% to 54% P 2 O 5 and gaseous ammonia to form an aqueous slurry of ammonium phosphate, the N:P atomic ratio of the slurry being fixed in the range 1.3 to 1.5 and the moisture content of the slurry being fixed in the range 10% to 20%, in such proportions as to form more slurry of substantially the same composition, simultaneously removing from the slurry an amount substantially equivalent to that produced from the phosphoric acid and ammonia, and mixing the removed amount of slurry with between 15% and 85% by volume of further "wet-process" phosphoric acid, thereafter adding the remainder of the "wet-process" phosphoric acid, whereby the product so formed solidifies and is of the desired N:P atomic ratio, the moisture disengagement being carried out under such conditions that the moisture content of the product is so reduced by evaporation that the product is solid at ambient temperature.
Claim 10
Dependent Claim
187 words
A process for producing a particulate solid product comprising ammonium phosphate of N:P atomic ratio in the range 0.95 to 1.10 is performed by mixing "wet-process" phosphoric acid of P 2 O 5 content in the range 30% to 54% P 2 O 5 and gaseous ammonia to form an aqueous slurry of ammonium phosphate, the N:P atomic ratio of the slurry being fixed in the range 1.3 to 1.5 and the moisture content of the slurry being fixed in the range 10% to 20%, in such proportions as to form more slurry of substantially the same composition, simultaneously removing from the slurry an amount substantially equivalent to that produced from the phosphoric acid and ammonia, and mixing the removed amount of slurry with between 15% and 85% by volume of further "wet-process" phosphoric acid, thereafter adding the remainder of the "wet-process" phosphoric acid, whereby the product so formed solidifies and is of the desired N:P atomic ratio, the moisture disengagement being carried out under such conditions that the moisture content of the product is so reduced by evaporation that the product is solid at ambient temperature.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-15 | 1980-08-16 | 1981-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-15 | 1984-08-16 | 1985-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-15 | 1988-08-16 | 1989-02-15 | $7700.00 | Window Closed / Lapsed |