Metal treatment system
First Claim
1. 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.
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Accused Products
Abstract
Molten aluminum or other metals are purified by contacting with a fluorocarbon, such as CCl2 F2, 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.
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Citations
38 Claims
- 1. 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.
- 2. 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 CF4 and favor oxidation of carbon to CO, said fluorine acceptor yielding fluorine values for treatment of said molten metal.
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3. 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.
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22. A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising:
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(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 CO2, thereby forming both CO and CO2 ; (b) contacting said fluorine values with a fluorine acceptor to substantially impede introduction of CF4 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. - View Dependent Claims (23, 24, 25, 35)
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26. A process for treating molten aluminum with reactive fluorine values in a fluorocarbon gas comprising:
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(a) contacting said fluorocarbon with oxygen, SiCl4 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, SiCl4 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 CO2 ; (f) said SiCl4 combining with said fluorine values to form substantial amounts of SiF4 and Cl2 while substantially reducing the amount of CF4 which would enter the molten aluminum but for the action of said SiCl4 ; (g) moving said carbon oxides, fluorine values, chlorine and nonreactive gas through a reducing media to reduce the substantial portions of said CO2 to CO; (h) passing said gases from said hollow chamber into said molten aluminum. - View Dependent Claims (36)
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Specification