Patent US4018877A successfully refreshed from Google Patents.
US4018877A
Expired / Lapsed
US
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Production of calcium carbonate
Assignee: Imperial Chemical Industries Ltd
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Filing: 1975-02-10
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Granted: 1977-04-19
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Expires: 1995-02-10
Abstract
Abstract Calcium carbonate is manufactured by the carbonation of an aqueous suspension of calcium hydroxide in the presence of a complex-forming agent for calcium ions which is added subsequently to the primary nucleation stage, and preferably during a first carbonation stage. Optionally there is also added a long-chain fatty acid or long-chain fatty acid salt, preferably after a final carbonation stage.
Inventors
- 👤 Richard Derek Anthony Woode
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:28
CPC Classifications
C; C01; C01F; C01F11/00; C01F11/18; C01F11/182; C01F11/183
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
61 words
In a process for the manufacture of calcium carbonate by carbonating an aqueous suspension of calcium hydroxide to produce calcium carbonate and separating the thus formed calcium carbonate, the improvement which comprises adding to the suspension, subsequently to a calcium carbonate primary nucleation stage of the carbonation step and before completion of the carbonation step, a complex-forming agent for calcium ions.
Claim 2
Dependent Claim
61 words
In a process for the manufacture of calcium carbonate by carbonating an aqueous suspension of calcium hydroxide to produce calcium carbonate and separating the thus formed calcium carbonate, the improvement which comprises adding to the suspension, subsequently to a calcium carbonate primary nucleation stage of the carbonation step and before completion of the carbonation step, a complex-forming agent for calcium ions.
Claim 3
Dependent Claim
38 words
A process as claimed in claim 1 in which the process comprises a first carbonation stage, an aging stage, and a subsequent second carbonation stage, and in which the complex-forming agent is added during the first carbonation stage.
Claim 4
Dependent Claim
21 words
A process according to claim 2 wherein a long-chain fatty acid or salt thereof is added after the second carbonation stage.
Claim 5
Dependent Claim
15 words
A process according to claim 1 wherein the complex-forming agent is a hydroxy polycarboxylic acid.
Claim 6
Dependent Claim
14 words
A process according to claim 4 wherein the hydroxy polycarboxylic acid is citric acid.
Claim 7
Dependent Claim
23 words
A process according to claim 1 wherein after completion of the carbonation there is added a long-chain fatty acid or a salt thereof.
Claim 8
Dependent Claim
19 words
A process according to claim 6 wherein said long-chain fatty acid or salt is stearic acid or ammonium stearate.
Claim 9
Dependent Claim
31 words
A process according to claim 6 wherein the proportion of weight of said fatty acid or salt thereof, based on the weight of calcium carbonate produced, is 0.001 to 3 percent.
Claim 10
Dependent Claim
31 words
A process according to claim 6 wherein the proportion by weight of said fatty acid or salt thereof, based on the weight of calcium carbonate produced, is 0.5 to 1 percent.
References Cited (Backward Citations)
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US3126253A
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Cited
US3347624A
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US3443890A
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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) | 1980-04-18 | 1980-10-18 | 1981-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-18 | 1984-10-18 | 1985-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-18 | 1988-10-18 | 1989-04-19 | $7700.00 | Window Closed / Lapsed |