Patent US1377559A successfully refreshed from Google Patents.
Patent US4173610A successfully refreshed from Google Patents.
US4173610A
Expired / Lapsed
US
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Process for the manufacture of lump calcium sulfate
Assignee: Knauf Gips KG
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Filing: 1977-12-20
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Granted: 1979-11-06
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Expires: 1997-12-20
Abstract
Abstract Pelletized calcium sulfate is prepared from finely divided, natural or synthetic calcium sulfate, wherein the particle size of the finely divided calcium sulfate is at least about 90 per cent by weight less than 200 μm, there being no particles larger than 500 μm, and wherein the finely divided calcium sulfate has a free water content of from about 0.5 to about 4 per cent by weight, by pressing the finely divided calcium sulfate in the presence of water with a roll press using a surface pressure of 1 to 5 Mp per cm roller length.
Inventors
- 👤 Rolf Huller
- 👤 Alfons Knauf
- 👤 Franz Wirsching
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:55
CPC Classifications
C; C04; C04B; C04B11/00; C04B11/26; C04B11/268
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
89 words
A process for the manufacture of calcium sulfate pellets from finely divided natural or synthetic calcium sulfate, which comprises: adjusting the free water content of the finely divided calcium sulfate to a value of from about 0.5 to about 4 percent by weight; and pressing the resultant finely divided calcium sulfate by means of a roll press using a surface pressure of from about 1 to about 5 Mp per cm of roller length, said pressing step being performed at a temperature between about 0° and about 60° C.
Claim 2
Dependent Claim
89 words
A process for the manufacture of calcium sulfate pellets from finely divided natural or synthetic calcium sulfate, which comprises: adjusting the free water content of the finely divided calcium sulfate to a value of from about 0.5 to about 4 percent by weight; and pressing the resultant finely divided calcium sulfate by means of a roll press using a surface pressure of from about 1 to about 5 Mp per cm of roller length, said pressing step being performed at a temperature between about 0° and about 60° C.
Claim 3
Dependent Claim
32 words
The process of claim 1, wherein the finely divided calcium sulfate contains at least about 90 weight percent of particles smaller than 200 μm and has no particles larger than 500 μm.
Claim 4
Dependent Claim
24 words
The process of claim 1, wherein the finely divided calcium sulfate has a degree of purity of at least about 80 percent by weight.
Claim 5
Dependent Claim
24 words
The process of claim 2, wherein the finely divided calcium sulfate has a degree of purity of at least about 80 percent by weight.
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) | 1982-11-05 | 1983-05-07 | 1983-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-05 | 1987-05-07 | 1987-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-05 | 1991-05-07 | 1991-11-06 | $7700.00 | Window Closed / Lapsed |