US4717558A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phosphorus recovery from phosphorus-containing pond sludge
Assignee: Occidental Chemical Corp
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Filing: 1986-10-29
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Granted: 1988-01-05
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Expires: 2006-10-29
Abstract
Abstract A process is described for recovering phosphorus from pond sludge found in ponds located near phosphorus plants. An aqueous solution of the sludge, which has a phosphorus concentration in the range of 5% to 70% by weight, is heated at a temperature in the range of 165 DEG F. to 212 DEG F., preferably for about 1/2 hour to about 6 hours, washed with water at an elevated temperature, and then reheated. A phosphorus layer having an enhanced concentration of recoverable elemental phosphorus is formed as a result of this process.
Inventors
- 👤 Steven M. Beck
- 👤 Edward H. Cook, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:38
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/02; C01B25/027; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
158 words
A process for recovering phosphorus from phosphorus-containing pond sludge having a phosphorus concentration of from about 5% to about 70% by weight, said sludge being an emulsion of phosphorus in water, said process comprising the steps of: (a) mixing the pond sludge with additional water and heating the mixture in a vessel under mild agitation at a temperature of from about 165° F. to about 212° F. for at least about one-half hour to increase said phosphorus concentration in the sludge, said mild agitation being effective to prevent the formation of layers of different composition within the vessel, (b) allowing the concentrated sludge to settle to the bottom of the vessel, (c) introducing water at a temperature of from about 130° F. to about 150° F. into the vessel to wash the concentrated sludge. (d) repeating step (a) to further increase said phosphorus concentration in the sludge from step (c), and (e) recovering said sludge from step (d).
Claim 2
Dependent Claim
158 words
A process for recovering phosphorus from phosphorus-containing pond sludge having a phosphorus concentration of from about 5% to about 70% by weight, said sludge being an emulsion of phosphorus in water, said process comprising the steps of: (a) mixing the pond sludge with additional water and heating the mixture in a vessel under mild agitation at a temperature of from about 165° F. to about 212° F. for at least about one-half hour to increase said phosphorus concentration in the sludge, said mild agitation being effective to prevent the formation of layers of different composition within the vessel, (b) allowing the concentrated sludge to settle to the bottom of the vessel, (c) introducing water at a temperature of from about 130° F. to about 150° F. into the vessel to wash the concentrated sludge. (d) repeating step (a) to further increase said phosphorus concentration in the sludge from step (c), and (e) recovering said sludge from step (d).
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein the pond sludge has a phosphorus concentration of from about 15% to about 40% by weight.
Claim 4
Dependent Claim
27 words
The process of claim 1 wherein the sludge in steps (a) and (d) is heated to a temperature of from about 170° F. to about 190° F.
Claim 5
Dependent Claim
20 words
The process of claim 1 wherein the recovered product has a phosphorus concentration of at least about 80% by weight.
Claim 6
Dependent Claim
28 words
The process of claim 1 wherein the sludge from step (d) is again washed with water at a temperature of from about 130° F. to about 150° F.
Claim 7
Dependent Claim
20 words
The process of claim 1 wherein the recovered product has a phosphorus concentration of at least about 90% by weight.
Claim 8
Dependent Claim
28 words
The process of claim 1 wherein the sludge in steps (a) and (d) is heated for a time period of from about 1/2 hour to about 6 hours.
Claim 9
Dependent Claim
34 words
The process of claim 1 wherein the ratio of the weight of sludge to the weight of water added in steps (a) and (d) is in the range of about 0.1 to about 2.0.
Claim 10
Dependent Claim
22 words
The process of claims 4 or 6 wherein said sludge from step (e) is filtered or evaporated to increase its phosphorus concentration.
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) | 1991-01-04 | 1991-07-06 | 1992-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-04 | 1995-07-06 | 1996-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-04 | 1999-07-06 | 2000-01-05 | $7700.00 | Window Closed / Lapsed |