US4314980A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of reactive beta-dicalcium silicate
Assignee: United States Department of Energy
•
Filing: 1980-02-28
•
Granted: 1982-02-09
•
Expires: 2000-02-28
Abstract
Abstract This invention relates to the preparation of fine particles of reactive beta-dicalcium silicate by means of a solid state process which comprises firing a mixture of calcium sulfate, silica and a reducing additive selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane and hydrogen, at a temperature of about 850°-1000° C. A carrier gas such as nitrogen or carbon dioxide may also be added, if desired. A high concentration of sulfur dioxide is a by-product of this process.
Inventors
- 👤 Ming-shing Shen
- 👤 James M. Chen
- 👤 Ralph T. Yang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:41
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
87 words
A method of producing beta-dicalcium silicate in the form of fine particles which exhibit high reactivity to sulfur dioxide and which are suitable for use in desulfurization processes which comprises preparing a stiochiometric mixture of finely powdered calcium sulfate, silica, and a reducing agent selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane and hydrogen, adding to said mixture a carrier gas selected from the group consisting of nitrogen and carbon dioxide, and subjecting the resulting mixture to thermal treatment at approximately 900° C.
Claim 2
Independent Claim
87 words
A method of producing beta-dicalcium silicate in the form of fine particles which exhibit high reactivity to sulfur dioxide and which are suitable for use in desulfurization processes which comprises preparing a stiochiometric mixture of finely powdered calcium sulfate, silica, and a reducing agent selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane and hydrogen, adding to said mixture a carrier gas selected from the group consisting of nitrogen and carbon dioxide, and subjecting the resulting mixture to thermal treatment at approximately 900° C.
Claim 3
Dependent Claim
26 words
A method in accordance with claim 1, wherein calcium sulfide is the reducing agent and the mole ratio of reactants is 3CaSO 4 :1CaS:2SiO 2 .
Claim 4
Dependent Claim
45 words
A method in accordance with claim 2, wherein the calcium sulfide is formed in situ during the thermal treatment by the reduction of a portion of the calcium sulfate with a reducing agent selected from the group consisting of carbon, carbon monoxide, methane and hydrogen.
Claim 5
Dependent Claim
13 words
A method in accordance with claim 1, wherein the carrier gas is nitrogen.
Claim 6
Dependent Claim
48 words
A method in accordance with claim 1, wherein the carrier gas is carbon dioxide formed in situ simultaneously with the in situ formation of calcium sulfide during the thermal treatment in the presence of a reducing agent selected from the group consisting of carbon, carbon monoxide and methane.
Claim 7
Dependent Claim
13 words
A method in accordance with claim 1, wherein the calcium sulfate is gypsum.
Claim 8
Dependent Claim
15 words
A method in accordance with claim 1, wherein the calcium sulfate is calcium sulfate anhydrite.
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) | 1985-02-08 | 1985-08-10 | 1986-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-02-08 | 1989-08-10 | 1990-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-02-08 | 1993-08-10 | 1994-02-09 | $7700.00 | Window Closed / Lapsed |