US5356607A
Expired / Lapsed
US
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Process for the hydrothermal production of crystalline sodium disilicate
Assignee: Henkel AG and Co KGaA
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Filing: 1992-06-02
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Granted: 1994-10-18
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Expires: 2012-06-02
Abstract
Abstract This invention is a process for the hydrothermal preparation of sodium disilicate with a molar ratio of Na 2 O:SiO 2 of 1:2 at an elevated temperature and a pressure corresponding to said temperature in a pressure vessel, characterized in that quartz sand and caustic soda solution and/or an aqueous solution of amorphous sodium disilicate at a total solids concentration of from 50 to 75% by weight are heated to at least 235° C. in a first step, the concentration may be increased in an optional second step by removing water from the reaction mixture, in a third step, dependent on whether the second step has been carried out, the amount of water removed in the second step is completely or partially added again to the mixture during or immediately after same has been cooled to from 90° C. to 130° C., and then the obtained crystalline sodium disilicate is recovered.
Inventors
- 👤 Guenther Just
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:57
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/32; C01B33/36; C01B33/38
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
170 words
A process for the hydrothermal preparation of solid, crystalline, sodium disilicate with a purity in excess of 95% in the β-form, with a molar ratio of Na 2 O:SiO 2 of 1:2, wherein: (A) quartz sand, caustic soda solution, and, optionally, an aqueous solution of amorphous sodium disilicate, in a molar ratio of Na 2 O:SiO 2 that corresponds to the composition of the desired final product and with a total solids concentration of from 50 to 75% by weight, are heated to a reaction temperature of at least 235° C. in a pressure vessel; and, optionally, (B) the concentration of the reaction mixture formed in step (A) is increased by removing water from the reaction mixture; and, if step (B) has been performed, (C) at least part of the amount of water removed in step (B) is added to the mixture formed in step (B) during or immediately after it has been cooled to from 90° C. to 130° C.; and (D) the obtained crystalline sodium disilicate is recovered.
Claim 2
Dependent Claim
170 words
A process for the hydrothermal preparation of solid, crystalline, sodium disilicate with a purity in excess of 95% in the β-form, with a molar ratio of Na 2 O:SiO 2 of 1:2, wherein: (A) quartz sand, caustic soda solution, and, optionally, an aqueous solution of amorphous sodium disilicate, in a molar ratio of Na 2 O:SiO 2 that corresponds to the composition of the desired final product and with a total solids concentration of from 50 to 75% by weight, are heated to a reaction temperature of at least 235° C. in a pressure vessel; and, optionally, (B) the concentration of the reaction mixture formed in step (A) is increased by removing water from the reaction mixture; and, if step (B) has been performed, (C) at least part of the amount of water removed in step (B) is added to the mixture formed in step (B) during or immediately after it has been cooled to from 90° C. to 130° C.; and (D) the obtained crystalline sodium disilicate is recovered.
Claim 3
Dependent Claim
18 words
A process according to claim 1, wherein the total solids concentration is from 60 to 70% by weight.
Claim 4
Dependent Claim
17 words
A process according to claim 2, wherein the reaction temperature is between 250° C. and 280° C.
Claim 5
Dependent Claim
40 words
A process according to claim 3, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 6
Dependent Claim
21 words
A process according to claim 4, wherein step (B) is included and is effected during the heating of the reaction mixture.
Claim 7
Dependent Claim
17 words
A process according to claim 2, wherein the reaction temperature is between 235° C. and 300° C.
Claim 8
Dependent Claim
17 words
A process according to claim 1, wherein the reaction temperature is between 235° C. and 300° C.
Claim 9
Dependent Claim
17 words
A process according to claim 7, wherein the reaction temperature is between 250° C. and 280° C.
Claim 10
Dependent Claim
40 words
A process according to claim 8, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 11
Dependent Claim
40 words
A process according to claim 7, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 12
Dependent Claim
40 words
A process according to claim 6, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 13
Dependent Claim
40 words
A process according to claim 5, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 14
Dependent Claim
40 words
A process according to claim 4, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 15
Dependent Claim
40 words
A process according to claim 2, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 16
Dependent Claim
40 words
A process according to claim 1, wherein an aqueous solution of amorphous sodium disilicate that consists of the mother liquor obtained upon the recovery of the crystalline sodium disilicate is recycled to step (A) of a repetition of the process.
Claim 17
Dependent Claim
21 words
A process according to claim 15, wherein step (B) is included and is effected during the heating of the reaction mixture.
Claim 18
Dependent Claim
21 words
A process according to claim 14, wherein step (B) is included and is effected during the heating of the reaction mixture.
Claim 19
Dependent Claim
21 words
A process according to claim 3, wherein step (B) is included and is effected during the heating of the reaction mixture.
Claim 20
Dependent Claim
21 words
A process according to claim 2, wherein step (B) is included and is effected during the heating of the reaction mixture.
Claim 21
Dependent Claim
21 words
A process according to claim 1, wherein step (B) is included and is effected during the heating of the reaction mixture.
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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) | 1997-10-17 | 1998-04-18 | 1998-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-17 | 2002-04-18 | 2002-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-17 | 2006-04-18 | 2006-10-18 | $7700.00 | Window Closed / Lapsed |