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Patent US4372810A successfully refreshed from Google Patents.
US4372810A
Expired / Lapsed
US
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Method and device for manufacturing mechanical pulp
Assignee: Valmet AB
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Filing: 1980-10-09
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Granted: 1983-02-08
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Expires: 2000-10-09
Abstract
Abstract A method and a device for the manufacture of mechanical pulp from lignocellulosic material by forcing the said material into contact with a grinding disc (1) which revolves about a central axle (2) perpendicular to the two end faces of the disc.. The material is supplied in bulk, particulate form, preferably as wood chips, a large number of particles simultaneously being retained, compressed and, in the presence of water, forced into contact with one or more grinding areas (5) on one or both end faces of the grinding disc. The disc is enclosed in a sealed, pressurized housing (6).
Inventors
- 👤 Hjalmar S. I. Bystedt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:13
CPC Classifications
D; D21; D21B; D21B1/00; D21B1/04; D21B1/12; D21B1/14; D21B1/18; D21B1/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
114 words
Method for manufacturing mechanical pulp from lignocellulosic material by forcing the said material into contact with opposite end faces of a single grinding disc (1) which revolves about a central axle (2) perpendicular to said two opposite end faces of the disc, which method is characterized in that the material is separately fed in bulk, particulate form to each face, a large number of particles of the said material simultaneously being retained against, compressed and, in the presence of water, forced directly into contact with one or more grinding areas (5) located on each of said opposite end faces of said single grinding disc, the disc being enclosed in a sealed, pressurized housing (6).
Claim 2
Dependent Claim
114 words
Method for manufacturing mechanical pulp from lignocellulosic material by forcing the said material into contact with opposite end faces of a single grinding disc (1) which revolves about a central axle (2) perpendicular to said two opposite end faces of the disc, which method is characterized in that the material is separately fed in bulk, particulate form to each face, a large number of particles of the said material simultaneously being retained against, compressed and, in the presence of water, forced directly into contact with one or more grinding areas (5) located on each of said opposite end faces of said single grinding disc, the disc being enclosed in a sealed, pressurized housing (6).
Claim 3
Dependent Claim
20 words
Method according to claim 1, characterized in that the pressure in the housing (6) is maintained by means of steam.
Claim 4
Dependent Claim
23 words
Method according to claim 1, characterized in that the pressure in the housing (6) is maintained by air or by an inert gas.
Claim 5
Dependent Claim
23 words
Method according to claim 1, characterized in that the pressure inside the housing (6) is between 100 and 400 to 1000 kPa absolute.
Claim 6
Dependent Claim
38 words
Method according to claim 1, characterized in that the material is fed to the grinding disc (1) through one or more openings (11) in the housing (6) in the form of a continuous steam-tight plug or short strand.
Claim 7
Dependent Claim
39 words
Method according to claim 1, characterized in that the particles of the material, before or during grinding, are impregnated or otherwise exposed to chemicals to soften the fibre bond, to adjust the acidity (pH) or to increase the brightness.
Claim 8
Dependent Claim
24 words
Method according to claim 4, characterized in that the pressure inside the housing (6) is between 150 and 250 kPa to 1000 kPa absolute.
Claim 9
Dependent Claim
16 words
Method according to claim 1, characterized in that the material in particulate form is wood chips.
References Cited (Backward Citations)
US3808090A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |