US4289662A
Expired / Lapsed
US
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Method of making crude boric acid from borate and sulfuric acid
Assignee: NO-TOX PRODUCTS Inc A CORP OF
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Filing: 1979-03-12
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Granted: 1981-09-15
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Expires: 1999-03-12
Abstract
Abstract For the conversion of sodium tetraborate (e.g. "5 mole borax" or sodium tetraborate pentahydrate) to a solid, particulate mass of flame-retardant chemical, using little or no water, 0.95 to 0.98 mole of sulfuric acid is added to convert the tetraborate to a moist, particulate mixture of boric acid and sodium sulfate. The moist particulate mixture is suitable for imparting flame retardancy to cellulosic insulation; preferably, however, it is first dried to <20 wt.-% moisture.
Inventors
- 👤 James R. Blasius
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:06
CPC Classifications
C; C01; C01B; C01B35/00; C01B35/08; C01B35/10; C01B35/1045; C01B35/1054; C01B35/1063; C09; C09K; C09K21/00; C09K21/02; Y; Y10; Y10S; Y10S428/00; Y10S428/92; Y10S428/921
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
82 words
A method for making an essentially dry, free-flowing particulate mixture comprising boric acid and sodium sulfate, said method comprising the steps of: a. introducing sodium tetraborate into a mixing zone; b. introducing 0.95-0.98 mole of sulfuric acid and exothermically reacting said sulfuric acid with said sodium tetraborate to obtain a mixture of sodium sulfate and boric acid; c. maintaining the temperature of said mixing zone above 100° C. but below about 150° C. until a generally free-flowing, moist, particulate mixture is obtained.
Claim 2
Independent Claim
82 words
A method for making an essentially dry, free-flowing particulate mixture comprising boric acid and sodium sulfate, said method comprising the steps of: a. introducing sodium tetraborate into a mixing zone; b. introducing 0.95-0.98 mole of sulfuric acid and exothermically reacting said sulfuric acid with said sodium tetraborate to obtain a mixture of sodium sulfate and boric acid; c. maintaining the temperature of said mixing zone above 100° C. but below about 150° C. until a generally free-flowing, moist, particulate mixture is obtained.
Claim 3
Dependent Claim
33 words
A method according to claim 1 comprising the additional steps of drying the said generally free-flowing, moist, particulate mixture to a moisture content below about 20% by weight and packaging the thus-dried product.
Claim 4
Dependent Claim
14 words
A method according to claim 1 wherein said sodium tetraborate is sodium tetraborate pentahydrate.
Claim 5
Independent Claim
125 words
A method for converting sodium tetraborate to a solid, particulate fire retardant mixture containing solid, particulate boric acid and sodium sulfate, said method comprising the steps of: (a) diluting about 0.95 to about 0.98 mole of sulfuric acid with a slurrying amount of water, and (b) blending, in a blending zone, the thus-diluted sulfuric acid with each mole of the sodium tetraborate, thereby forming a reaction medium in the blending zone, (c) maintaining the temperature of said reaction medium generally within the range of about 100° to about 175° C., (d) recovering from the blending zone a solid, particulate fire retardant mixture which has been dried by the reaction exotherm of the reaction medium but retains a moisture content in excess of 20% by weight.
Claim 6
Independent Claim
125 words
A method for converting sodium tetraborate to a solid, particulate fire retardant mixture containing solid, particulate boric acid and sodium sulfate, said method comprising the steps of: (a) diluting about 0.95 to about 0.98 mole of sulfuric acid with a slurrying amount of water, and (b) blending, in a blending zone, the thus-diluted sulfuric acid with each mole of the sodium tetraborate, thereby forming a reaction medium in the blending zone, (c) maintaining the temperature of said reaction medium generally within the range of about 100° to about 175° C., (d) recovering from the blending zone a solid, particulate fire retardant mixture which has been dried by the reaction exotherm of the reaction medium but retains a moisture content in excess of 20% by weight.
Claim 7
Dependent Claim
50 words
A method according to claim 4 wherein said fire retardant mixture is dried further, at a product temperature below 100° C., to a moisture content below 20% by weight, the thus-dried mixture containing sodium sulfate and at least 30% by weight B 2 O 3 , generally as boric acid.
Claim 8
Dependent Claim
21 words
A method according to claim 4 wherein the said temperature of said reaction medium is maintained by cooling said blending zone.
Claim 9
Dependent Claim
37 words
A method according to claim 4 wherein the sodium tetraborate is sodium tetraborate pentahydrate of more than 99 weight-% purity, and said slurrying amount of water is 3 to 10 moles per mole of the sodium tetraborate.
Claim 10
Independent Claim
137 words
A method for converting sodium tetraborate to a solid, particulate fire retardant mixture containing solid, particulate boric acid and sodium sulfate, said method comprising the steps of: (a) blending, in a blending zone, sufficient concentrated sulfuric acid of at least 90% by weight H 2 SO 4 content with the sodium tetraborate to provide about 0.95 to about 0.98 mole of sulfuric acid for each mole sodium tetraborate, whereby the amount of water present in said blending zone is not sufficient to form a uniform slurry, (b) maintaining the temperature in said blending zone generally within the range of about 100° to about 175° C., and (c) recovering from the blending zone a generally dry, free-flowing particulate fire-retardant mass containing sodium sulfate and at least 30% by weight B 2 O 3 , generally as boric acid.
Claim 11
Independent Claim
137 words
A method for converting sodium tetraborate to a solid, particulate fire retardant mixture containing solid, particulate boric acid and sodium sulfate, said method comprising the steps of: (a) blending, in a blending zone, sufficient concentrated sulfuric acid of at least 90% by weight H 2 SO 4 content with the sodium tetraborate to provide about 0.95 to about 0.98 mole of sulfuric acid for each mole sodium tetraborate, whereby the amount of water present in said blending zone is not sufficient to form a uniform slurry, (b) maintaining the temperature in said blending zone generally within the range of about 100° to about 175° C., and (c) recovering from the blending zone a generally dry, free-flowing particulate fire-retardant mass containing sodium sulfate and at least 30% by weight B 2 O 3 , generally as boric acid.
Claim 12
Dependent Claim
16 words
A method according to claim 8 wherein said temperature is maintained by cooling said blending zone.
Claim 13
Dependent Claim
20 words
A method according to claim 8 wherein the sodium tetraborate is sodium tetraborate pentahydrate of more than 99 weight-% purity.
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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) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |