Patent US4943368A successfully refreshed from Google Patents.
US4943368A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nonmetallic abrasive blasting material recovery process including an electrostatic separation step
Assignee: Pittsburgh Mineral and Environmental Technology Inc
•
Filing: 1989-02-27
•
Granted: 1990-07-24
•
Expires: 2009-02-27
Abstract
Abstract An electrostatic waste separation process for abrasive blasting residues containing an abrasive media and a hazardous material such as lead-based paint. A preconditioning stage as well as a postconditioning stage is used in addition to the electrostatic separation step. Preferably the preconditioning stage consists of the following steps: (a) a size classification step; (b) a ferromagnetic separation step; and (c) a gravity separation step. The concentrated hazardous material separated by this process can then be packaged in a container which can be safely transported, stored or disposed of. The nonhazardous blasting media may be recycled and reused or disposed of as a nonhazardous material.
Inventors
- 👤 Stanley R. Gilbert
- 👤 Thomas E. Weyand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:40
CPC Classifications
B; B07; B07B; B07B9/00; B03; B03B; B03B9/00; B03B9/06; B03B9/061; B24; B24C; B24C9/00; B24C9/006; Y; Y02; Y02P; Y02P70/00; Y02P70/10; Y02W; Y02W30/00; Y02W30/50; Y02W30/52
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
128 words
A dry abrasive blasting residue separation process wherein a nonmetallic abrasive blasting material is separated from the blasting residue comprising: (a) a size classification step to eliminate large objects form the abrasive blasting residue and to concentrate the residue for further processing; (b) a ferromagnetic separation step to remove ferrous objects from the blasting residue which would interfere with further processing of it; (c) a gravity separation step to reclaim large particles of the nonmetallic abrasive blasting material from the blasting residue and to concentrate the fine blasting residue containing fine particles of the nonmetallic abrasive blasting material and nonconducting paint particles; and (d) an electrostatic separation step to reclaim the fine particles of the nonmetallic abrasive blasting material and separate it from the fine nonconducting paint particles.
Claim 2
Dependent Claim
21 words
The separation process as described in claim 1 wherein the electrostatic separation step is accomplished using a two stage electrostatic separation.
Claim 3
Dependent Claim
25 words
The separation process as described in claim 1 wherein the nonmetallic abrasive blasting material is selected from the group consisting of sand, slag and garnet.
Claim 4
Dependent Claim
14 words
The separation process as described in claim 1 wherein the paint particles contain lead.
Claim 5
Dependent Claim
21 words
The separation process as described in claim 1 wherein the size classification step separates the blasting residue into three screen fractions.
Claim 6
Dependent Claim
18 words
The separation process as described in claim 1 wherein the ferromagnetic separation step utilizes low intensity magnetic fields.
Claim 7
Dependent Claim
19 words
The separation process as described in claim 1 wherein the gravity separation step is accomplished using an air table.
References Cited (Backward Citations)
DE206940C
Cited
US3401795A
Cited
US3322275A
Cited
US3460296A
Cited
US3625360A
Cited
GB1370801A
Cited
US3865629A
Cited
US3970546A
Cited
US4800063A
Cited
US4671867A
Cited
US4773189A
Cited
US4827678A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-23 | 1994-01-22 | 1994-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-23 | 1998-01-22 | 1998-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-23 | 2002-01-22 | 2002-07-24 | $7700.00 | Window Closed / Lapsed |