US4988376A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Glassification of lead and silica solid waste
Assignee: Western Research Institute Inc
•
Filing: 1989-08-02
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Granted: 1991-01-29
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Expires: 2009-08-02
Abstract
Abstract Lead or other heavy metals are rendered immobile for sanitary disposal by vitrifying the silica-based soil or other medium in which the lead or heavy metal is contained. The silica sand or other soil contaminated with lead is heated to the melting point of the silica. A melt accelerator or fluxing agent is added to lower the melting point of the silica. A reducing agent is added to cause a separation of the metallic phases from the glass. The glass formed retains a portion of the lead, with excess metals, e.g., gold, silver, and platinum, separating. These metals may be recovered at any time after this point in the process. In the case of a silica-poor medium, such as a soil that does not contain sufficient quartz to perform the process successfully, additional quartz sand or scrap glass is added to the process in quantity sufficient to ensure the formation of the glass slag. The slag formed by the process of the present invention is extremely impervious to leaching by groundwater, therefore removing the contaiminate from the environment.
Inventors
- 👤 Glenn M. Mason
- 👤 Gerald Gardner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:12
CPC Classifications
B; B09; B09C; B09C1/00; B09C1/06; B09C1/067; B09C1/08; C; C03; C03C; C03C1/00; C03C1/002
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
58 words
A process for treating solid wastes lead contaminated soils and waste containing lead containing paint chips in solid waste immobile consisting essentially of heating said solid wastes with a fluxing agent to a temperature sufficient to melt silica present in said solid waste and the lead contained therein, to form a slag and recovering the slag so formed.
Claim 2
Dependent Claim
58 words
A process for treating solid wastes lead contaminated soils and waste containing lead containing paint chips in solid waste immobile consisting essentially of heating said solid wastes with a fluxing agent to a temperature sufficient to melt silica present in said solid waste and the lead contained therein, to form a slag and recovering the slag so formed.
Claim 3
Dependent Claim
17 words
The process according to claim 1 wherein a reducing agent is further included with the fluxing agent.
Claim 4
Dependent Claim
68 words
The process according to claim 1 wherein the fluxing agent is selected from the group consisting of trona, barium oxide, barium carbonate, calcium oxide, calcium carbonate, calcium borate, dolomite, calcium fluoride, calcium phosphate, wollastonite, calcium silicate, lithium oxide, lepidolite, spudomene, lithium carbonate, petalite, amblygonite, potassium oxide, potassium carbonate, feldspar, Cornwall stone, Caroline stone, sodium oxide, sodium chloride, sodium carbonate, sodium bicarbonate, borax, soda feldspar, nepheline syenite, and colemanite.
Claim 5
Dependent Claim
12 words
The process according to claim 3 wherein the fluxing agent is trona.
Claim 6
Dependent Claim
27 words
The process according to claim 2 wherein the reducing agent is selected from the group consisting of wheat flour, charcoal, sulfur containing compounds, and carbon containing compounds.
Claim 7
Dependent Claim
13 words
The process according to claim 5 wherein the reducing agent is wheat flour.
Claim 8
Dependent Claim
12 words
The process according to claim 5 wherein the reducing agent is charcoal.
Claim 9
Dependent Claim
20 words
A process according to claim 1 wherein silica is added to said solid waste to ensure formation of a slag.
Claim 10
Dependent Claim
34 words
A process for recovering precious metals from solid wastes comprising subjecting said solid wastes to the process according to claim 2 and recovering said precious metals from the bottom of the slag so formed.
Claim 11
Dependent Claim
21 words
The process according to claim 9 wherein said precious metals are selected from the group consists of gold, silver, and platinum.
Claim 12
Dependent Claim
18 words
The process according to claim 1 wherein additional quartz or scrap glass is added to the waste material.
Claim 13
Dependent Claim
21 words
The process according to claim 1 wherein the silica is present in an amount of at least about 5% by weight.
Claim 14
Dependent Claim
33 words
The process according to claim 1 wherein the flux is added in amount sufficient to melt the mixture of metal and silica at a temperature of from about 1000° to about 1200° C.
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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) | 1994-01-28 | 1994-07-30 | 1995-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-28 | 1998-07-30 | 1999-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-28 | 2002-07-30 | 2003-01-29 | $7700.00 | Window Closed / Lapsed |