US3997331A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metallized salts
Assignee: Crysus (Lanchashire) Ltd
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Filing: 1973-08-13
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Granted: 1976-12-14
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Expires: 1993-08-13
Abstract
Abstract A process and apparatus for producing certain metal salts in very fine particulate form. The process comprises cooling a solution of metal salt until the solution freezes and thereafter evaporating the solvent under very low pressure. The process is particularly applicable to salts of tungsten and nickel from which sub-micron particles of tungsten and nickel can be produced.
Inventors
- 👤 Denis Tither
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:30
CPC Classifications
C; C01; C01G; C01G53/00; C01G53/10; B; B01; B01D; B01D3/00; B01D3/14; B01D3/16; B01D9/00; B01D9/0004; B01D9/0013; B01D9/0059; B01J; B01J13/00; B01J13/0086; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/20; B22F9/22; C01G41/00; C01G53/08; C01G53/09; C01G53/80; C01G53/82; C01P; C01P2004/00; C01P2004/01; C01P2004/03
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
117 words
A process for producing particles of ammonium paratungstate and characterized in that under X-ray analysis no diffracted lines are observed, which process comprises the steps of placing a solution of ammonium paratungstate in a chamber, closing the chamber, reducing the pressure within the chamber below atmospheric pressure, freezing the solution by the combined effect of admitting to the chamber a liquid refrigerant which is inert to said ammonium paratungstate whereby the liquid refrigerant evaporates, the amount of liquid refrigerant admitted to the chamber being not sufficient to raise the pressure in the chamber to atmospheric pressure and circulating a cold fluid through heat exchange means in said chamber, and thereafter evaporating the solvent from the frozen solution.
Claim 2
Dependent Claim
117 words
A process for producing particles of ammonium paratungstate and characterized in that under X-ray analysis no diffracted lines are observed, which process comprises the steps of placing a solution of ammonium paratungstate in a chamber, closing the chamber, reducing the pressure within the chamber below atmospheric pressure, freezing the solution by the combined effect of admitting to the chamber a liquid refrigerant which is inert to said ammonium paratungstate whereby the liquid refrigerant evaporates, the amount of liquid refrigerant admitted to the chamber being not sufficient to raise the pressure in the chamber to atmospheric pressure and circulating a cold fluid through heat exchange means in said chamber, and thereafter evaporating the solvent from the frozen solution.
Claim 3
Dependent Claim
26 words
A process as claimed in claim 1, wherein the pressure in the chamber is further reduced after the admission of said liquid refrigerant into the chamber.
Claim 4
Dependent Claim
27 words
A process as claimed in claim 1, wherein the pressure in the chamber rises by not more than 100 mm when said liquid refrigerant is admitted thereto.
Claim 5
Dependent Claim
30 words
A process as claimed in claim 1, wherein the solvent content of the frozen solution is reduced by the said evaporation to not more than 10% of the original weight.
Claim 6
Dependent Claim
18 words
A process as claimed in claim 1, wherein salt is recovered after evaporation and sieved to recover particles.
Claim 7
Dependent Claim
21 words
A process as claimed in claim 5, wherein particles of ammonium paratungstate having a size less than 10μ are recovered. d
Claim 8
Dependent Claim
16 words
A process as claimed in claim 6, wherein the ammonium paratungstate is reduced to tungsten metal.
References Cited (Backward Citations)
US3175881A
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US3357819A
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US3451764A
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US3516935A
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US3440732A
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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) | 1979-12-14 | 1980-06-14 | 1980-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-12-14 | 1984-06-14 | 1984-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-12-14 | 1988-06-14 | 1988-12-14 | $7700.00 | Window Closed / Lapsed |