Patent US4102784A successfully refreshed from Google Patents.
US4102784A
Expired / Lapsed
US
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Colloid free precipitation of heavy metal sulfides
Assignee: Individual
•
Filing: 1977-05-23
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Granted: 1978-07-25
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Expires: 1997-05-23
Abstract
Abstract In an aqueous solution heavy metal pollutant ions are removed as a precipitate formed by adding an insoluble slurry of a metal sulfide salt. The supernatant liquid is free of colloids.
Inventors
- 👤 Richard M. Schlauch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:46
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
116 words
A method of precipitating heavy metal pollutant ions from aqueous solution, comprising: (a) forming an aqueous solution of a water soluble sulfide; (b) adding a water soluble ferrous salt in the presence of sufficient base to maintain the pH above 7 thru the entire precipitating process, to the thus formed sulfide solution, to form a large particle size slurry of ferrous sulfide precipitate having a higher equilibrium sulfide ion concentration than the sulfide of the heavy metal pollutant in said aqueous solution; (c) adding said slurry of (b) in the presence of a polyelectrolyte, to the aqueous solution containing dissolved heavy metal pollutant ions to form a colloid free metal ion precipitate; (d) removing said precipitate.
Claim 2
Independent Claim
116 words
A method of precipitating heavy metal pollutant ions from aqueous solution, comprising: (a) forming an aqueous solution of a water soluble sulfide; (b) adding a water soluble ferrous salt in the presence of sufficient base to maintain the pH above 7 thru the entire precipitating process, to the thus formed sulfide solution, to form a large particle size slurry of ferrous sulfide precipitate having a higher equilibrium sulfide ion concentration than the sulfide of the heavy metal pollutant in said aqueous solution; (c) adding said slurry of (b) in the presence of a polyelectrolyte, to the aqueous solution containing dissolved heavy metal pollutant ions to form a colloid free metal ion precipitate; (d) removing said precipitate.
Claim 3
Dependent Claim
13 words
A method of claim 1, wherein the heavy metal pollutant ion is bivalent.
Claim 4
Dependent Claim
22 words
A method of claim 2 wherein the bivalent heavy metal is selected from the group consisting of copper, zinc, nickel and lead.
Claim 5
Dependent Claim
18 words
The method of claim 1 where the particle diameter of 90% of slurry is at least 50 microns.
Claim 6
Dependent Claim
25 words
The method of claim 1 wherein the step (b) the metal salt is added slowly to the sulfide solution and stirred at a controlled rate.
Claim 7
Dependent Claim
16 words
The method of claim 1 where the temperature of the slurry is maintained between 13°-25° C.
Claim 8
Dependent Claim
30 words
The method of claim 1 wherein the step (b) the ferrous salt added to the sulfide is up to 10% in excess of stoichiometric amount required to precipitate sulfide ion.
Claim 9
Dependent Claim
27 words
The method of claim 1 wherein the step (c) the slurry is added slowly to the aqueous solution so as not to shear down its particle size.
References Cited (Backward Citations)
US3474033A
Cited
US3740331A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-07-24 | 1982-01-23 | 1982-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-24 | 1986-01-23 | 1986-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-24 | 1990-01-23 | 1990-07-25 | $7700.00 | Window Closed / Lapsed |