US3856511A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of crude aluminum
Assignee: Ethyl Corp
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Filing: 1974-02-20
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Granted: 1974-12-24
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Expires: 1994-02-20
Abstract
Abstract A process for purifying or upgrading crude aluminum by reacting sodium fluoride with a source of impure aluminum, e.g., an aluminum alloy, to obtain cryolite. The cryolite is then reacted with sodium metal to produce purified aluminum metal and sodium fluoride.
Inventors
- 👤 C Hildreth
- 👤 W Becker
- 👤 J Johnston
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:27
CPC Classifications
C; C22; C22B; C22B21/00; C22B21/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
132 words
A PROCESS FOR REFINING AN IMPURE ALUMINUM-CONTAINING SOURCE MATERIAL, COMPRISING: A. HEATING THE IMPURE ALUMINUM-CONTAINING SOURCE MATERIAL WITH SODIUM FLUORIDE IN A FIRST REACTION ZONE TO A TEMPERATURE HIGH ENOUGH TO INITIATE REACTION BUT BELOW 1,000*C AND EFFECTING THE REACTION AT A REDUCED PRESSURE OF LESS THAN ABOUT 100 MILLIMETERS OF MERCURY, THEREBY AVOIDING THE FORMATION OF ALUMINUM MONO FLUORIDE AND PRODUCING CRYOLITE, RESIDUE, AND METALLIC SODIUM, AND CAUSING SAID METALLIC SODIUM TO BE VAPORIZED OUT OF SAID REACTION ZONE AND SEPARATELY CONDENSED FROM SAID CRYOLITE; AND B. REACTING THE CRYOLITE PRODUCED IN STEP (A) WITH METALLIC SODIUM IN A SECOND REACTION ZONE AT ELEVATED TEMPERATURE AND AT A PRESSURE AT LEAST AS HIGH AS NORMAL ATMOSPHERIC TO KEEP THE SODIUM FORM BOILING OUT, THEREBY PRODUCING PURIFIED METALLIC ALUMINUM AND SODIUM FLUORIDE.
Claim 2
Dependent Claim
132 words
A PROCESS FOR REFINING AN IMPURE ALUMINUM-CONTAINING SOURCE MATERIAL, COMPRISING: A. HEATING THE IMPURE ALUMINUM-CONTAINING SOURCE MATERIAL WITH SODIUM FLUORIDE IN A FIRST REACTION ZONE TO A TEMPERATURE HIGH ENOUGH TO INITIATE REACTION BUT BELOW 1,000*C AND EFFECTING THE REACTION AT A REDUCED PRESSURE OF LESS THAN ABOUT 100 MILLIMETERS OF MERCURY, THEREBY AVOIDING THE FORMATION OF ALUMINUM MONO FLUORIDE AND PRODUCING CRYOLITE, RESIDUE, AND METALLIC SODIUM, AND CAUSING SAID METALLIC SODIUM TO BE VAPORIZED OUT OF SAID REACTION ZONE AND SEPARATELY CONDENSED FROM SAID CRYOLITE; AND B. REACTING THE CRYOLITE PRODUCED IN STEP (A) WITH METALLIC SODIUM IN A SECOND REACTION ZONE AT ELEVATED TEMPERATURE AND AT A PRESSURE AT LEAST AS HIGH AS NORMAL ATMOSPHERIC TO KEEP THE SODIUM FORM BOILING OUT, THEREBY PRODUCING PURIFIED METALLIC ALUMINUM AND SODIUM FLUORIDE.
Claim 3
Dependent Claim
36 words
The process of claim 1, wherein at least a portion of the cryolite formed in the first reaction zone in step (a) is vaporized out of the first reaction zone along with the vaporized sodium metal.
Claim 4
Dependent Claim
54 words
The process of claim 1, wherein said impure aluminum-containing source material contains at least 40 percent by weight of aluminum, from about 5 to about 50 percent by weight of silicon, from about 0.1 to about 40 percent by weight of iron, and from about 0.001 to about 10 percent by weight of titanium.
Claim 5
Dependent Claim
19 words
The process of claim 1, wherein said pressure in step (a) is less than about 10 millimeters of mercury.
Claim 6
Dependent Claim
17 words
The process of claim 1, wherein said temperature in step (a) is about 700*C to about 1,000*C.
Claim 7
Dependent Claim
17 words
The process of claim 1, wherein said temperature in step (b) is about 1,000*C to about 1,300*C.
Claim 8
Dependent Claim
21 words
The process of claim 1, wherein the reactions are conducted in the presence of a melting point depressant for the fluoride.
Claim 9
Dependent Claim
32 words
The process of claim 1, wherein the cryolite and residue are formed together in step (a) and then heated to melt the cryolite and then separating the molten cryolite from the residue.
Claim 10
Dependent Claim
14 words
The process of claim 1, wherein the reactions are conducted in an inert atmosphere.
Claim 11
Dependent Claim
21 words
The process of claim 1, in which the pressure in step (a) is not greater than 10116 4 millimeters of mercury.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |