Claims
- 1. A process for refining a high-carbon ferro-alloy, comprising the steps of:
- preparing a bath of melted high-carbon ferro-alloy to be refined, said ferro-alloy being selected from the group which consists of ferrochrome and ferromanganese;
- preheating said bath to an overall temperature higher than the melting point of said ferro-alloy;
- blowing oxygen together with an enveloping protective gas into the preheated bath, in jets trained upon a region spaced from the boundaries of the bath and located below the surface thereof, at a rate sufficient to cause local superheating of the melt, due to interaction of the oxygen with the ferro-alloy, in said region to a reaction temperature higher than said overall temperature at which carbon contained in the melt is oxidized by contact with the products of said interaction;
- determining changes in said overall temperature; and
- controlling the flow of oxygen to prevent a rise of said overall temperature above a predetermined limit.
- 2. A process as defined in claim 1 wherein the flow of oxygen is controlled to raise said overall temperature from an initial level lying between substantially 1200.degree. and 1600.degree. C. to a final level lying between substantially 1650.degree. and 2000.degree. C.
- 3. A process as defined in claim 2, wherein the oxygen is blown in at a rate of substantially 10 to 30 cubic meters S.T.P. within a unit period t, said unit period ranging between substantially 0.1 and 2 minutes, the duration of the blow being pqt wherein p is the number of weight-percent of carbon to be removed from the bath and q is the total quantity of ferro-alloy in metric tons.
- 4. A process as defined in claim 2 wherein said component is manganese, said final level being established at not more than 1900.degree. C.
- 5. A process as defined in claim 2 wherein said component is chromium, said final level being established at not less than 1750.degree. C.
- 6. A process as defined in claim 2, comprising the further step of blowing powdered lime into said region upon termination of the oxygen blow for reacting with high-melting oxides of said component.
- 7. A process as defined in claim 6, comprising the further step of depositing a reducing agent on said bath simultaneously with the introduction of said lime.
- 8. A process as defined in claim 1, comprising the further step of introducing a minor fraction of said ferro-alloy in a solid state into said bath.
- 9. A process as defined in claim 8 wherein said minor fraction has substantially the same composition as the melted ferro-alloy.
- 10. A process as defined in claim 8 wherein the amount of said minor fraction ranges up to about 20%, by weight, of the total quantity of said ferro-alloy.
- 11. A process as defined in claim 1 wherein the oxygen is blown in at a rate sufficient to remove 1 weight-percent carbon from the bath in a time of 1 to 15 minutes.
- 12. A process as defined in claim 1 wherein said jets are introduced into the melt, at a level lying about 25 to 80 cm below the bath surface, with a velocity ranging between substantially 100 and 1000 meters per second.
- 13. A process for refining a high-carbon ferro-alloy selected from the group which consists of ferrochrome and ferromanganese, comprising the steps of:
- preparing a bath of melted high-carbon ferro-alloy to be refined;
- preheating said bath to an initial temperature higher than the melting point of said ferro-alloy, said initial temperature lying between substantially 1200.degree. and 1600.degree. C.;
- blowing oxygen together with an enveloping protective gas into the preheated bath for a time sufficient to cause the removal of a significant proportion of carbon from said ferro-alloy, at a rate controlled to raise the bath temperature to a final level lying between substantially 1650.degree. and 2000.degree. C.;
- blowing powdered lime into the melt upon termination of the oxygen blow for reacting with higher-melting oxides of said nonferrous component; and
- depositing a reducing agent on said bath.
- 14. A process as defined in claim 13 wherein the ferro-alloy is ferromanganese, said final level being established at not more than 1900.degree. C.
- 15. A process as defined in claim 13 wherein the ferro-alloy is ferrochrome, said final level being established at not less than 1750.degree. C.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2531034 |
Jul 1975 |
DEX |
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2540290 |
Sep 1975 |
DEX |
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Parent Case Info
This is a continuation of application Ser. No. 704,098, filed July 9, 1976, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3909245 |
Brotzmann |
Sep 1975 |
|
3955965 |
Putzier |
May 1976 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
704098 |
Jul 1976 |
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