US4242318A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the preparation of aqueous suspensions containing at least 65% by weight of calcium carbonate
Assignee: Solvay SA
•
Filing: 1978-07-10
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Granted: 1980-12-30
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Expires: 1998-07-10
Abstract
Abstract Process for the preparation of an aqueous suspension containing at least 65% by weight of calcium carbonate, in which process calcium carbonate is crystallized in a dilute aqueous medium, a wet concentrate of calcium carbonate is separated from the resulting dilute aqueous suspension of calcium carbonate and the said calcium carbonate concentrate is fluidized and homogenized in the presence of a dispersing agent. The calcium carbonate is crystallized in the presence of a water-soluble polyelectrolyte and the calcium carbonate concentrate is separated from the dilute suspension of calcium carbonate by essentially mechanical separating means.
Inventors
- 👤 Jacques Brahm
- 👤 Jean-Pierre De Rath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:47
CPC Classifications
C; C09; C09D; C09D17/00; C09D17/004; C01; C01F; C01F11/00; C01F11/18; C01F11/182; C01F11/183; C01F11/185; C09C; C09C1/00; C09C1/02; C09C1/021; D; D21; D21H; D21H19/00; D21H19/36; D21H19/38; D21H19/385; D21H19/44; D21H19/52; C01P; C01P2004/00; C01P2004/51; C01P2004/60; C01P2004/61; C01P2004/62
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
120 words
A process for the preparation of an aqueous suspension of calcium carbonate comprising: (a) crystallizing calcium carbonate by carbonating in a dilute aqueous medium a source of calcium ions with a source of carbonate ions in the presence of a water-soluble polyelectrolyte to obtain a dilute aqueous suspension of calcium carbonate; (b) separating a wet concentrate of calcium carbonate from the dilute aqueous suspension of calcium carbonate by essentially mechanical separating means to obtain directly a wet concentrate of calcium carbonate containing at least 65% by weight calcium carbonate; and (c) fluidizing and homogenizing said wet concentrate in the presence of a dispersing agent to obtain an aqueous suspension of calcium carbonate containing at least 65% by weight calcium carbonate.
Claim 2
Dependent Claim
120 words
A process for the preparation of an aqueous suspension of calcium carbonate comprising: (a) crystallizing calcium carbonate by carbonating in a dilute aqueous medium a source of calcium ions with a source of carbonate ions in the presence of a water-soluble polyelectrolyte to obtain a dilute aqueous suspension of calcium carbonate; (b) separating a wet concentrate of calcium carbonate from the dilute aqueous suspension of calcium carbonate by essentially mechanical separating means to obtain directly a wet concentrate of calcium carbonate containing at least 65% by weight calcium carbonate; and (c) fluidizing and homogenizing said wet concentrate in the presence of a dispersing agent to obtain an aqueous suspension of calcium carbonate containing at least 65% by weight calcium carbonate.
Claim 3
Dependent Claim
17 words
Process according to claim 1, wherein the polyelectrolyte is selected from polyacids and their alkali metal salts.
Claim 4
Dependent Claim
37 words
Process according to claim 2, wherein the polyelectrolyte is selected from polyacids of weakly acid character and having a pK greater than 4 as measured on a 0.01N solution in pure water, and their alkali metal salts.
Claim 5
Dependent Claim
30 words
Process according to claim 3, wherein the polyelectrolyte is selected from polyacids derived from polymers containing at least one carboxyl group per 10 carbon atoms and their alkali metal salts.
Claim 6
Dependent Claim
32 words
Process according to claim 4, wherein the polyelectrolyte is selected from polymers derived from acrylic, methacrylic and alpha-hydroxyacrylic acids, maleic acid copolymers, carboxylated derivatives of cellulose ethers, and their alkali metal salts.
Claim 7
Dependent Claim
12 words
Process according to claim 5, wherein the polyelectrolyte is a sodium polyacrylate.
Claim 8
Dependent Claim
12 words
Process according to claim 5, wherein the polyelectrolyte is a sodium poly-alpha-hydroxyacrylate.
Claim 9
Dependent Claim
38 words
Process according to claim 1, wherein the amount of polyelectrolyte in the dilute aqueous medium for the crystallization is controlled so that the resulting dilute suspension contains between 1 and 10 g of polyelectrolyte per kg of solids.
Claim 10
Dependent Claim
22 words
Process according to claim 8, wherein the resulting dilute suspension contains between 2 and 6 g of polyelectrolyte per kg of solids.
Claim 11
Dependent Claim
19 words
Process according to claim 1, wherein a milk of lime is carbonated in order to crystallize the calcium carbonate.
Claim 12
Dependent Claim
19 words
Process according to claim 10, wherein the milk of lime is carbonated with a gas containing CO 2 .
Claim 13
Dependent Claim
21 words
Process according to claim 10, wherein the milk of lime is carbonated at a temperature of between 25° and 60° C.
Claim 14
Dependent Claim
19 words
Process according to claim 1, wherein the mechanical separating means comprises filtration of the dilute suspension of calcium carbonate.
Claim 15
Dependent Claim
12 words
Process according to claim 1, wherein the mechanical separating means comprises draining.
Claim 16
Dependent Claim
47 words
Process according to claim 13 wherein the mechanical separating means which filters the dilute aqueous suspension of calcium carbonate further comprises means to drain the resulting filter cake by compressing it and sweeping it with a stream of air without substantial evaporation of the liquid taking place.
Claim 17
Dependent Claim
29 words
Process according to claim 1, wherein between 2 and 10 g of dispersing agent per kg of calcium carbonate are used for fluidizing and homogenizing the calcium carbonate concentrate.
Claim 18
Dependent Claim
16 words
Process according to claim 16, wherein between 4 and 8 g of dispersing agent are used.
Claim 19
Dependent Claim
17 words
Process according to claim 1, wherein the dispersing agent is introduced directly into the calcium carbonate concentrate.
Claim 20
Dependent Claim
23 words
Process according to claim 1, wherein said aqueous suspension obtained in step (c) contains between 65 and 80% by weight of calcium carbonate.
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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) | 1983-12-30 | 1984-06-30 | 1984-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-30 | 1988-06-30 | 1988-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-30 | 1992-06-30 | 1992-12-30 | $7700.00 | Window Closed / Lapsed |