US3637519A
Expired / Lapsed
US
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Method for thermally refining precipitated haloapatites
Assignee: Mallinckrodt Chemical Works
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Filing: 1969-07-22
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Granted: 1972-01-25
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Expires: 1989-07-22
Abstract
Abstract Precipitated alkaline earth haloapatites containing antimony as an activator are thermally refined by heating them first to a temperature of at least 800* C. in an oxidizing atmosphere to remove ammonia and water without reducing the antimony. Thereafter, the haloapatites may be further thermally refined by being heated at 1,050*-1,200* C. in an inert atmosphere to complete the refining treatment. This method avoids loss of antimony and other activators and produces a significantly brighter phosphor product.
Inventors
- 👤 Roger D Piper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:19
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/74; C09K11/75; C09K11/76
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
12 words
The method according to claim 1 wherein the oxidizing atmosphere is air.
Claim 2
Independent Claim
91 words
A method of thermally refining precipitated alkaline earth haloapatite material containing antimony and manganese as activators which haloapatite material has been precipitated in the presence of ammonium ions comprising continuously moving said material through a furnace, heating said material to a temperature of at least 800* C. in a first zone of said furnace in which is maintained an oxidizing atmoSphere, and thereafter heating the material to a temperature between about 1,050* C. and about 1,200* C. in a second zone of said furnace in which is maintained an inert atmosphere.
Claim 3
Dependent Claim
20 words
The method according to claim 3 wherein the two heating steps are carried out in separate furnaces operated in series.
References Cited (Backward Citations)
GB717653A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-24 | 1975-07-26 | 1976-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-24 | 1979-07-26 | 1980-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-24 | 1983-07-26 | 1984-01-25 | $7700.00 | Window Closed / Lapsed |