US4392888A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metal treatment system
Assignee: Alcoa Corp
•
Filing: 1982-01-07
•
Granted: 1983-07-12
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Expires: 2002-01-07
Abstract
Abstract Molten aluminum or other metals are purified by contacting with a fluorocarbon, such as CCl2F2, in order to decrease the amount of impurity metal elements along with gas and inclusions therein preferably in the presence of an agitator to enhance efficiency. An oxidizer, such as oxygen, is employed to prevent the carbon in the fluorocarbon from forming carbide inclusions. Oxidizing the carbon to carbon monoxide is preferred in treating aluminum since the monoxide effectively removes the carbon from the system without oxidizing aluminum. Preferably, a fluorine acceptor is employed to temporarily combine with the fluorine in the fluorocarbon and prevent it from reacting with carbon such that the fluoride is still available to treat the molten metal. The gases employed to treat the molten metal can be passed over a bed of carbon immediately prior to introduction into the melt. The system operates with low skim generation and without providing a salt cover and is capable of substantially fume-free operation.
Inventors
- 👤 Charles E. Eckert
- 👤 Ronald E. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:35
CPC Classifications
C; C22; C22B; C22B9/00; C22B9/05; C22B9/055; C22B21/00; C22B21/06; C22B21/066
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
47 words
In a process for treating molten metal wherein said metal is contacted with halogen values from a gas containing a halocarbon the improvement comprising contacting said halocarbon with an oxidizer under conditions to oxidize carbon constituent thereof prior to introducing said halogen values into the molten metal.
Claim 2
Dependent Claim
47 words
In a process for treating molten metal wherein said metal is contacted with halogen values from a gas containing a halocarbon the improvement comprising contacting said halocarbon with an oxidizer under conditions to oxidize carbon constituent thereof prior to introducing said halogen values into the molten metal.
Claim 3
Dependent Claim
76 words
In a process for treating molten metal wherein said metal is contacted with fluorine values contained in a halocarbon containing fluorine the improvement comprising contacting said halocarbon with an oxidizer under conditions to oxidize substantial portions of the carbon therein to carbon monoxide and with a fluorine acceptor to impede contacting the molten metal with CF 4 and favor oxidation of carbon to CO, said fluorine acceptor yielding fluorine values for treatment of said molten metal.
Claim 4
Dependent Claim
76 words
In a process for treating molten metal wherein said metal is contacted with fluorine values contained in a halocarbon containing fluorine the improvement comprising contacting said halocarbon with an oxidizer under conditions to oxidize substantial portions of the carbon therein to carbon monoxide and with a fluorine acceptor to impede contacting the molten metal with CF 4 and favor oxidation of carbon to CO, said fluorine acceptor yielding fluorine values for treatment of said molten metal.
Claim 5
Dependent Claim
62 words
In a process for treating molten metal wherein said metal is contacted with halogen values from a gas comprising a halocarbon, the improvement comprising reacting carbon in said halocarbon to produce a carbonaceous reaction product more stable in the treatment process than said halocarbon, but non-deleterious to said metal and said treatment process, prior to contacting said metal with said halogen values.
Claim 6
Dependent Claim
62 words
In a process for treating molten metal wherein said metal is contacted with halogen values from a gas comprising a halocarbon, the improvement comprising reacting carbon in said halocarbon to produce a carbonaceous reaction product more stable in the treatment process than said halocarbon, but non-deleterious to said metal and said treatment process, prior to contacting said metal with said halogen values.
Claim 7
Dependent Claim
11 words
The improvement according to claim 1 wherein said oxidizer comprises oxygen.
Claim 8
Dependent Claim
23 words
The improvement according to claim 1 wherein said oxidizer comprises oxygen provided in an amount stoichiometrically related to the carbon in said halocarbon.
Claim 9
Dependent Claim
12 words
The improvement according to claim 2 wherein said fluorine acceptor comprises silicon.
Claim 10
Dependent Claim
22 words
The improvement according to claim 1 wherein a nonreactive gas is employed in said process in an amount greater than said halocarbon.
Claim 11
Dependent Claim
22 words
The improvement according to claim 2 wherein a nonreactive gas is employed in said process in an amount greater than said halocarbon.
Claim 12
Dependent Claim
26 words
The improvement according to claim 1 wherein a nonreactive gas is employed in said process in a volume ratio of at least 2:1 with said halocarbon.
Claim 13
Dependent Claim
26 words
The improvement according to claim 2 wherein a nonreactive gas is employed in said process in a volume ratio of at least 9:1 with said halocarbon.
Claim 14
Dependent Claim
17 words
The improvement according to claim 2 wherein said fluorine acceptor comprises silicon provided as SiCl 4 .
Claim 15
Dependent Claim
17 words
The improvement according to claim 2 wherein said fluorine acceptor comprises silicon provided as SiO 2 .
Claim 16
Dependent Claim
61 words
The improvement according to claim 1 wherein said oxidizer is oxygen used in an amount stoichiometrically in excess of that required to oxidize the carbon in said halocarbon to CO by up to about 30% excess whereby some CO 2 is formed and said CO 2 is passed over carbon at an elevated temperature prior to introduction into said molten metal.
Claim 17
Dependent Claim
11 words
The improvement according to claim 1 wherein said halocarbon contains fluorine.
Claim 18
Dependent Claim
31 words
The improvement according to claim 1 wherein said halocarbon contains fluorine and is contacted with a fluorine acceptor to impede production of CF 4 and favor said oxidation of said carbon.
Claim 19
Dependent Claim
23 words
The improvement according to claim 2 wherein said fluorine acceptor's fluoride is more stable than CF 4 and the oxide of said acceptor.
Claim 20
Dependent Claim
13 words
The improvement according to claim 16 wherein said fluorine acceptor's fluoride is gaseous.
Claim 21
Dependent Claim
29 words
The improvement according to claim 16 wherein said fluorine acceptor's fluoride is less stable than the fluoride of one or more metals present in the molten metal being treated.
Claim 22
Dependent Claim
16 words
The improvement according to claim 1 wherein said molten metal comprises aluminum or the alloys thereof.
Claim 23
Dependent Claim
16 words
The improvement according to claim 2 wherein said molten metal comprises aluminum or the alloys thereof.
Claim 24
Dependent Claim
81 words
The improvement according to claim 2 wherein said oxidizer is oxygen used in an amount stoichiometrically in excess of that required to oxidize the carbon in said halocarbon to CO by up to about 30% excess whereby some CO 2 is formed and said CO 2 is passed over carbon at an elevated temperature prior to introduction into said molten metal, said excess of oxidizer not being in excess of that required to oxidize all the carbon to CO 2 .
Claim 25
Dependent Claim
132 words
A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising: (a) contacting said fluorocarbon with oxygen to oxidize carbon values therein to one or more carbon oxides, said oxygen being provided in excess of the stoichiometric equivalent to react said carbon values to CO, but insufficient to react all said carbon values to CO 2 , thereby forming both CO and CO 2 ; (b) contacting said fluorine values with a fluorine acceptor to substantially impede introduction of CF 4 to the molten aluminum; (c) combining said fluorine values with a nonreactive gas, the amount by volume of said nonreactive gas exceeding the amount of said fluorine values as gas to form a mixture of said gases; and (d) introducing said gas mixture into said molten aluminum.
Claim 26
Dependent Claim
132 words
A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising: (a) contacting said fluorocarbon with oxygen to oxidize carbon values therein to one or more carbon oxides, said oxygen being provided in excess of the stoichiometric equivalent to react said carbon values to CO, but insufficient to react all said carbon values to CO 2 , thereby forming both CO and CO 2 ; (b) contacting said fluorine values with a fluorine acceptor to substantially impede introduction of CF 4 to the molten aluminum; (c) combining said fluorine values with a nonreactive gas, the amount by volume of said nonreactive gas exceeding the amount of said fluorine values as gas to form a mixture of said gases; and (d) introducing said gas mixture into said molten aluminum.
Claim 27
Dependent Claim
12 words
The improvement according to claim 22 wherein said fluorine acceptor comprises silicon.
Claim 28
Dependent Claim
20 words
The improvement according to claim 22 wherein said CO 2 is passed over carbon before introduction into said molten aluminum.
Claim 29
Dependent Claim
29 words
The improvement according to claim 22 wherein said fluorine acceptor's fluoride is gaseous and less stable than the fluoride of one or more metals contained in said molten aluminum.
Claim 30
Dependent Claim
224 words
A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising: (a) contacting said fluorocarbon with oxygen, SiCl 4 and a nonreactive gas; (b) providing a treatment chamber for said molten aluminum including therein a rotating agitator having a hollow shaft therein to provide a hollow space in said shaft, said hollow space being provided with an exit in the region of said agitator; (c) introducing said fluorocarbon, oxygen, SiCl 4 and nonreactive gas into the said hollow space in said agitator shaft; (d) heating said gases in said agitator shaft to a temperature exceeding 1000° F.; (e) said oxygen being provided in an amount stoichiometrically in excess by 10 to 30% of the amount required to react the carbon constituent in said fluorocarbon to CO, thereby to react said carbon values to form both CO and CO 2 ; (f) said SiCl 4 combining with said fluorine values to form substantial amounts of SiF 4 and Cl 2 while substantially reducing the amount of CF 4 which would enter the molten aluminum but for the action of said SiCl 4 ; (g) moving said carbon oxides, fluorine values, chlorine and nonreactive gas through a reducing media to reduce the substantial portions of said CO 2 to CO; (h) passing said gases from said hollow chamber into said molten aluminum.
Claim 31
Dependent Claim
224 words
A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising: (a) contacting said fluorocarbon with oxygen, SiCl 4 and a nonreactive gas; (b) providing a treatment chamber for said molten aluminum including therein a rotating agitator having a hollow shaft therein to provide a hollow space in said shaft, said hollow space being provided with an exit in the region of said agitator; (c) introducing said fluorocarbon, oxygen, SiCl 4 and nonreactive gas into the said hollow space in said agitator shaft; (d) heating said gases in said agitator shaft to a temperature exceeding 1000° F.; (e) said oxygen being provided in an amount stoichiometrically in excess by 10 to 30% of the amount required to react the carbon constituent in said fluorocarbon to CO, thereby to react said carbon values to form both CO and CO 2 ; (f) said SiCl 4 combining with said fluorine values to form substantial amounts of SiF 4 and Cl 2 while substantially reducing the amount of CF 4 which would enter the molten aluminum but for the action of said SiCl 4 ; (g) moving said carbon oxides, fluorine values, chlorine and nonreactive gas through a reducing media to reduce the substantial portions of said CO 2 to CO; (h) passing said gases from said hollow chamber into said molten aluminum.
Claim 32
Dependent Claim
13 words
The improvement according to claim 1 wherein the carbonaceous-oxidizer reaction product is gaseous.
Claim 33
Dependent Claim
13 words
The improvement according to claim 2 wherein the carbonaceous-oxidizer reaction product is gaseous.
Claim 34
Dependent Claim
24 words
The improvement according to claim 1 wherein said oxidation reaction is substantially effected before the halogenaceous values in said halocarbon contact the molten metal.
Claim 35
Dependent Claim
24 words
The improvement according to claim 2 wherein said oxidation reaction is substantially effected before the halogenaceous values in said halocarbon contact the molten metal.
Claim 36
Dependent Claim
29 words
The improvement according to claim 1 wherein said halocarbon and said oxidizer react within a hollow portion of a rotating agitator shaft prior to introduction into said molten metal.
Claim 37
Dependent Claim
29 words
The improvement according to claim 2 wherein said halocarbon and said oxidizer react within a hollow portion of a rotating agitator shaft prior to introduction into said molten metal.
Claim 38
Dependent Claim
22 words
The improvement according to claim 1 wherein said molten metal, after said treatment with said halocarbon, is moved through a filter bed.
Claim 39
Dependent Claim
22 words
The improvement according to claim 2 wherein said molten metal, after said treatment with said halocarbon, is moved through a filter bed.
Claim 40
Dependent Claim
22 words
The improvement according to claim 22 wherein said molten metal, after said treatment with said halocarbon, is moved through a filter bed.
Claim 41
Dependent Claim
22 words
The improvement according to claim 26 wherein said molten metal, after said treatment with said halocarbon, is moved through a filter bed.
Claim 42
Dependent Claim
24 words
The improvement according to claim 1 wherein said molten metal contains halogenizable metal impurities which are reacted with said halogen values in said process.
Claim 43
Dependent Claim
24 words
The improvement according to claim 2 wherein said molten metal contains fluoridizable metal impurities which are reacted with said fluorine values in said process.
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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) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |