Patent US3650686A successfully refreshed from Google Patents.
US3650686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for recovery of phosphorous values from dilute plant effluents
Assignee: Monsanto Co
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Filing: 1969-08-18
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Granted: 1972-03-21
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Expires: 1989-08-18
Abstract
Abstract The process of recovering phosphorus values from plant effluents by precipitating the phosphorus values with lime to obtain a sludge which is difficult to handle is improved by treating the sludge with phosphoric acid so as to convert phosphorus values in the sludge from basic calcium phosphate to crystalline calcium phosphates which are readily filterable and useful as an animal feed supplement.
Inventors
- 👤 Robert B Hudson
- 👤 Robert E Mesmer
- 👤 Roger A Rose
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:54
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/322; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
38 words
The process of claim 1 wherein the sludge-phosphoric acid slurry during the formation of said dicalcium phosphate containing solids is maintained at a temperature of about 10* C. to about 40* C. whereby dicalcium phosphate dihydrate is formed.
Claim 2
Dependent Claim
35 words
reacting in a primary reactor said lime slurry with additional amounts of said effluent stream in such a ratio that a substantial amount of the lime slurry remains unreacted to obtain a primary reaction mixture,
Claim 3
Dependent Claim
26 words
reacting in a secondary reactor said primary reaction mixture with additional amounts of said effluent stream to obtain a sludge containing small amounts of unreacted lime,
Claim 4
Dependent Claim
38 words
The process of claim 1 wherein the sludge-phosphoric acid slurry during the formation of said dicalcium phosphate containing solids is maintained at a temperature of about 70* C. to about 100* C. whereby anhydrous dicalcium phosphate is formed.
Claim 5
Dependent Claim
45 words
The process of claim 1 wherein the sludge-phosphoric acid slurry during the formation of said dicalcium phosphate containing solids is maintained at a temperature of about 40* C. to about 70* C. whereby a mixture of dicalcium phosphate dihydrate and anhydrous dicalcium phosphate is formed.
Claim 6
Dependent Claim
33 words
adding the sludge to and reacting it with sufficient phosphoric acid to provide in the resulting mixture a pH of from pH 4 to pH 9 whereby crystalline calcium phosphate is formed, and
Claim 7
Dependent Claim
5 words
recovering the crystallized calcium phosphate.
Claim 8
Dependent Claim
43 words
The process of claim 1 wherein the phosphoric acid contains from about 30 to about 85 percent by weight P2O5 and wherein an amount of phosphoric acid is employed such that said slurry has an end pH of from 6.5 to 7.5, inclusive.
Claim 9
Dependent Claim
31 words
The process of claim 5 wherein the principal constituent of the phosphoric acId is orthophosphoric acid and wherein said slurry is formed by addition of said sludge to said phosphoric acid.
Claim 10
Dependent Claim
19 words
A process for the recovery of phosphorus values from an effluent liquid stream containing dilute soluble phosphate values comprising
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-21 | 1975-09-20 | 1976-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-21 | 1979-09-20 | 1980-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-21 | 1983-09-20 | 1984-03-21 | $7700.00 | Window Closed / Lapsed |