US4629509A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Immobilization of lead and cadmium in fly ash
Assignee: Honeywell International Inc
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Filing: 1985-06-24
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Granted: 1986-12-16
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Expires: 2005-06-24
Abstract
Abstract Leaching of cadmium and lead from solid residues obtained in the incineration of refuse may be reduced to environmentally acceptable levels by the addition of calcium sulfide to such residues. A particularly convenient method involves the addition of dry lime and an aqueous solution of an inorganic salt supplying sulfide, especially an alkali metal sulfide, in equimolar quantities.
Inventors
- 👤 Mark J. O'Hara
- 👤 Peter Urban
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:59
CPC Classifications
C; C04; C04B; C04B18/00; C04B18/04; C04B18/06; C04B18/10; C04B18/105; C04B18/106; B; B09; B09B; B09B3/00; B09B3/70; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/91; Y10; Y10S; Y10S106/00; Y10S106/01; Y10S106/90
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
69 words
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with an amount sufficient to reduce the leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm of approximately equimolar proportions of lime and an aqueous solution of a soluble inorganic salt supplying sulfide.
Claim 2
Independent Claim
69 words
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with an amount sufficient to reduce the leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm of approximately equimolar proportions of lime and an aqueous solution of a soluble inorganic salt supplying sulfide.
Claim 3
Dependent Claim
12 words
The method of claim 1 where the solid residue is fly ash.
Claim 4
Dependent Claim
13 words
The method of claim 1 where the inorganic salt is an inorganic sulfide.
Claim 5
Dependent Claim
13 words
The method of claim 3 where the sulfide is an alkali metal sulfide.
Claim 6
Dependent Claim
11 words
The method of claim 4 where the sulfide is sodium sulfide.
Claim 7
Dependent Claim
15 words
The method of claim 3 where the inorganic sulfide is an alkaline earth metal sulfide.
Claim 8
Dependent Claim
21 words
The method of claim 1 where the inorganic salt is an alkali metal sulfide, alkali metal polysulfide, or alkali metal hydrosulfide.
Claim 9
Independent Claim
54 words
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with calcium sulfide in an amount effective to reduce leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm.
Claim 10
Independent Claim
54 words
A method of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes comprising mixing said residue with calcium sulfide in an amount effective to reduce leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm.
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) | 1989-12-15 | 1990-06-16 | 1990-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-15 | 1994-06-16 | 1994-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-15 | 1998-06-16 | 1998-12-16 | $7700.00 | Window Closed / Lapsed |