Patent US3920802A successfully refreshed from Google Patents.
US3920802A
Expired / Lapsed
US
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Process for preparation of hot-pressable magnesium fluoride
Assignee: Solon Technologies Inc
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Filing: 1974-03-04
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Granted: 1975-11-18
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Expires: 1994-03-04
Abstract
Abstract A process is disclosed for converting basic magnesium carbonate into pure hot-pressable magnesium fluoride such as is used for the hot-pressing of infra-red radiation transmitting optical bodies. The process includes contacting a slurry of basic magnesium carbonate with carbon dioxide to form enough magnesium bicarbonate or hydrates of magnesium carbonate, in situ, to alter the particles in the slurry. Carbonation of the slurry increases solubility of the solids by establishing an equilibrium relationship in solution between the unstable magnesium bicarbonate and hydrates of magnesium carbonate particles. When the carbonated slurry is contacted with a slight excess of hydrofluoric acid it precipitates solid particles of fine hydrous magnesium fluoride. Neutralization of excess hydrofluoric acid is effected with ammonium hydroxide. The solid particulate precipitate is dried and calcined to yield hot-pressable magnesium fluoride powder of exceptional purity and consistent quality. A hot-pressable magnesium fluoride powder has been prepared which has a specific and uniform refractive index, nD 1.3850 at 20* C; the powder is made up of primary particles the majority of which have an average particle diameter of greater than 5 Mu (microns), permitting the hot-pressing of the powder without grinding it.
Inventors
- 👤 Robert H Moss
- 👤 Carl F Swinehart
- 👤 William F Spicuzza
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:18
CPC Classifications
G; G02; G02B; G02B1/00; C; C01; C01F; C01F5/00; C01F5/26; C01F5/28; C01P; C01P2002/00; C01P2002/01; C01P2002/80; C01P2002/82; C01P2004/00; C01P2004/51; C01P2004/60; C01P2004/61
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
153 words
A PROCESS FOR THE PREPARATION OF PRESSABLE MAGNESIUM FLUORIDE CONSISTING ESSENTIALLY OF DEFORMABLE PARTICLES WHICH MAY BE PHYSICALLY DEFORMED UNDER SUFFICIENTLY HIGH HEAT AND PRESSURE CONDITIONS TO FORM AN OPTICAL BODY CHARACTERIZED BY IN EXCESS OF 90 PERCENT TRANSMITTANCE OF INFRA-RED RADIATION OVER A RANGE OF WAVELENGTH OF UP TO ABOUT 10 MICRONS, SAID PROCESS COMPRISING: A. FORMING A SLURRY OF BASIC MAGNESIUM CARBONATE; B. SATURATING SAID SLURRY WITH CARBON DIOXIDE TO FORM AT LEAST SOME MAGNESIUM BICARBONATE; C. CONTACTING SAID SLURRY WITH EXCESS AQUEOUS HYDROFLUORIC ACID TO CONVERT ALL MAGNESIUM COMPOUNDS IN SAID SL!RRY TO MAGNESIUM FLUORIDE, THEN D. ADJUSTING THE PH TO FALL IN THE RANGE FROM ABOUT 2 TO ABOUT 4; E. RECOVERING SAID MAGNESIUM FLUORIDE FORMED, F. REMOVING MOISTURE FROM SAID MAGNESIUM FLUORIDE TO YIELD MAGNESIUM FLUORIDE POWDER; AND G. HEAT-TREATING RECOVERED MAGNESIUM FLUORIDE POWDER AT A TEMPERATURE BELOW ABOUT 600*C TO YIELD DISCRETE PARTICLES OF SAID PRESSABLE POWDER.
Claim 2
Dependent Claim
153 words
A PROCESS FOR THE PREPARATION OF PRESSABLE MAGNESIUM FLUORIDE CONSISTING ESSENTIALLY OF DEFORMABLE PARTICLES WHICH MAY BE PHYSICALLY DEFORMED UNDER SUFFICIENTLY HIGH HEAT AND PRESSURE CONDITIONS TO FORM AN OPTICAL BODY CHARACTERIZED BY IN EXCESS OF 90 PERCENT TRANSMITTANCE OF INFRA-RED RADIATION OVER A RANGE OF WAVELENGTH OF UP TO ABOUT 10 MICRONS, SAID PROCESS COMPRISING: A. FORMING A SLURRY OF BASIC MAGNESIUM CARBONATE; B. SATURATING SAID SLURRY WITH CARBON DIOXIDE TO FORM AT LEAST SOME MAGNESIUM BICARBONATE; C. CONTACTING SAID SLURRY WITH EXCESS AQUEOUS HYDROFLUORIC ACID TO CONVERT ALL MAGNESIUM COMPOUNDS IN SAID SL!RRY TO MAGNESIUM FLUORIDE, THEN D. ADJUSTING THE PH TO FALL IN THE RANGE FROM ABOUT 2 TO ABOUT 4; E. RECOVERING SAID MAGNESIUM FLUORIDE FORMED, F. REMOVING MOISTURE FROM SAID MAGNESIUM FLUORIDE TO YIELD MAGNESIUM FLUORIDE POWDER; AND G. HEAT-TREATING RECOVERED MAGNESIUM FLUORIDE POWDER AT A TEMPERATURE BELOW ABOUT 600*C TO YIELD DISCRETE PARTICLES OF SAID PRESSABLE POWDER.
Claim 3
Dependent Claim
17 words
The process of claim 1 wherein hydrates of magnesium carbonate are formed together with said magnesium bicarbonate.
Claim 4
Dependent Claim
16 words
The process of claim 1 wherein adjusting the pH includes washing said magnesium fluoride with water.
Claim 5
Dependent Claim
23 words
The process of claim 3 wherein said washing is effected until the pH is in the range from about 2.5 to about 3.
Claim 6
Dependent Claim
31 words
The process of claim 1 wherein adjusting the pH includes neutralizing essentially all excess acid with a base to form a fluoride thereof, and expelling said fluoride from said magnesium fluoride.
Claim 7
Dependent Claim
221 words
A wet process for precipitating magnesium fluoride particles in a predetermined particle size range from finely divided basic magnesium carbonate solids comprising, preparing a aqueous fluent paste or slurry of said solids, contacting said slurry with sufficient carbon dioxide at a temperature below about 60*C and at a pressure sufficient to convert a minor portion of said basic magnesium carbonate to magnesium bicarbonate and hydrates of magnesium carbonate, said carbon dioxide being present in an amount at least sufficient to saturate said aqueous slurry, thereafter adding said slurry to aqueous hydrofluoric acid present in an amount in excess of that theoretically required to convert all said magnesium carbonate hydrates, magnesium carbonate and magnesium bicarbonate to magnesium fluoride, adding ammonium hydroxide to react with excess hydrofluoric acid so as to maintain a pH in the range from about 2 to about 4, recovering solid magnesium fluoride particles, drying said particles to remove moisture and yield a powder, and calcining said powder at a temperature in the range from about 500*C to about 600*C to yield a pressable powder consisting essentially of deformable particles which may be physically deformed under sufficiently high heat and pressure conditions to form an optical body chaRacterized by transmittance of infra-red radiation in excess of about 90 percent over a range of wavelength up to about 10 microns.
Claim 8
Dependent Claim
221 words
A wet process for precipitating magnesium fluoride particles in a predetermined particle size range from finely divided basic magnesium carbonate solids comprising, preparing a aqueous fluent paste or slurry of said solids, contacting said slurry with sufficient carbon dioxide at a temperature below about 60*C and at a pressure sufficient to convert a minor portion of said basic magnesium carbonate to magnesium bicarbonate and hydrates of magnesium carbonate, said carbon dioxide being present in an amount at least sufficient to saturate said aqueous slurry, thereafter adding said slurry to aqueous hydrofluoric acid present in an amount in excess of that theoretically required to convert all said magnesium carbonate hydrates, magnesium carbonate and magnesium bicarbonate to magnesium fluoride, adding ammonium hydroxide to react with excess hydrofluoric acid so as to maintain a pH in the range from about 2 to about 4, recovering solid magnesium fluoride particles, drying said particles to remove moisture and yield a powder, and calcining said powder at a temperature in the range from about 500*C to about 600*C to yield a pressable powder consisting essentially of deformable particles which may be physically deformed under sufficiently high heat and pressure conditions to form an optical body chaRacterized by transmittance of infra-red radiation in excess of about 90 percent over a range of wavelength up to about 10 microns.
Claim 9
Dependent Claim
37 words
The process of claim 6 including, after adding said slurry to said hydrofluoric acid, maintaining a temperature in the range from about 60* C to about 80* C at ambient pressure until the reaction is essentially complete.
Claim 10
Dependent Claim
42 words
The process of claim 1 including recovering said powder in a relatively free-flowing form, said powder including more than 50 percent by weight of particles having a primary particle size in the range from about 5 Mu to about 62 Mu .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |