Method for treating a carbon dioxide-containing waste gas from an electrofusion process

1. A method for treatment of a carbon dioxide-containing waste gas from an electric smelting process, comprising:

supplying the waste gas to a re-combustion system and subjecting the waste gas to a re-combustion process performed in the re-combustion system to produce a re-combusted gas;

feeding a hydrocarbon-containing gas to the re-combusted gas to produce a reacted gas, the hydrocarbon-containing gas converting at least a portion of the carbon dioxide of the re-combusted gas into a carbon monoxide-hydrogen mixture;

cooling the reacted gas in a heat exchange process; and

supplying the carbon monoxide-hydrogen mixture to the re-combustion system and using the carbon monoxide-hydrogen mixture as a combustion gas in the re-combustion system.

2. The method as claimed in claim 1 , wherein, in addition to the hydrocarbon-containing gas, water is added to the re-combusted gas obtained from the re-combustion system and the water is used in a reaction that converts carbon monoxide and water into carbon dioxide and hydrogen.

3. The method as claimed in claim 1 , wherein

the electric smelting process uses an electric arc furnace that produces the waste gas, and

in the supplying the waste gas, the waste gas is supplied from the electric arc furnace.

4. A method for treatment of a carbon dioxide-containing waste gas from an electric smelting process, comprising:

performing a re-combustion process on the waste gas, using a combustion gas, the re-combustion process producing a re-combusted gas containing carbon dioxide;

feeding a hydrocarbon-containing gas to the re-combusted gas to produce a reacted gas, the hydrocarbon-containing gas converting at least a portion of the carbon dioxide of the re-combusted gas into a carbon monoxide-hydrogen mixture;

cooling the reacted gas in a heat exchange process to form a cooled reacted gas containing the carbon monoxide-hydrogen mixture; and

using the cooled reacted gas containing the carbon monoxide-hydrogen mixture in a thermal process.

5. The method as claimed in claim 4 , wherein

the electric smelting process uses an electric arc furnace, and

the waste gas is produced in the electric arc furnace.

6. The method as claimed in claim 5 , wherein the thermal process is another cycle of the re-combustion process and the carbon monoxide-hydrogen mixture is used as a combustion gas in the another cycle of the re-combustion process.

7. The method as claimed in claim 5 , wherein the thermal process is another combustion process of a steel smelting process and the carbon monoxide-hydrogen mixture is used as a combustion gas in the another combustion processes.

8. The method as claimed in claim 4 , further comprising:

storing the reacted gas along with the carbon monoxide-hydrogen mixture in a gas holder prior to use in the thermal process.

9. The method as claimed in claim 8 , wherein the thermal process is another cycle of the re-combustion process and the carbon monoxide-hydrogen mixture is used as a combustion gas in the another cycle of the re-combustion process.

10. The method as claimed in claim 8 , wherein the thermal process is another combustion process of a steel smelting process and the carbon monoxide-hydrogen mixture is used as a combustion gas in the another combustion processes.

11. The method as claimed in claim 4 , wherein, in addition to the hydrocarbon-containing gas, water is added to the re-combusted gas.

12. The method as claimed in claim 11 , wherein the water serves to convert carbon monoxide into carbon dioxide and hydrogen.

13. The method as claimed in claim 11 , wherein

the water converts carbon monoxide into carbon dioxide and hydrogen, and

the water serves to control a ratio of carbon monoxide to hydrogen in the reacted gas.

14. The method according to claim 4 , wherein the thermal process is a further combustion process.

15. The method as claimed in claim 4 , wherein

when the hydrocarbon-containing gas is fed to the re-combusted gas, carbon dioxide in the re-combusted gas enters into an endothermic reaction with the hydrocarbon-containing gas, and

the re-combusted gas is cooled by the endothermic reaction to produce the reacted gas.

16. The method as claimed in claim 4 , wherein the hydrocarbon-containing gas contains methane.

17. The method as claimed in claim 4 , wherein the heat exchange process uses a heat exchanger to exchange heat between the reacted gas and a heat exchange medium.

18. The method as claimed in claim 4 , further comprising:

monitoring a carbon-dioxide content of the waste gas using a gas sensor, to regulate a supply of the hydrocarbon-containing gas.