CO2 Blowing in Steel Melt Decarburization
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Solution Overview
Problem
Current metallurgical treatments for carbon-containing molten metals, such as decarburization, desiliconization, and dephosphorization, often rely on oxygen, nitrogen, or argon, which are not economically efficient and do not effectively manage slag formation and oxide reduction.
Innovation Solution
Blowing carbon dioxide into the molten metal to facilitate the Boudouard reaction, producing carbon monoxide, which enhances mixing, decarburization, desiliconization, and dephosphorization processes, while also serving as a cooling gas and reducing chromium oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxygen, nitrogen or argon is used as process gas for metallurgical treatment, then decarburization can be achieved, but the process is not economically efficient and does not effectively manage slag formation and oxide reduction
Solution Approach 1:
The invention changes the chemical composition parameter of the process gas from conventional oxygen/nitrogen/argon to a specific mixture containing CO (20-80 vol%), CO2 (10-50 vol%), and H2 (5-30 vol%). This parameter change enables both economic efficiency and effective slag management through the synergistic effects of these gases in the还原 zone
Solution Approach 2:
The invention uses a composite process gas mixture rather than a single gas. The combination of CO, CO2, and H2 creates a synergistic effect where CO provides strong reducing power for slag and oxide reduction, CO2 contributes to endothermic cooling and carbon removal, and H2 enhances reducing capability and temperature control, collectively solving both economic and technical challenges
2Productivity
If oxygen is blown into the metal melt for decarburization, then carbon removal is achieved, but the process is exothermic and requires careful temperature control
Solution Approach 1:
The invention changes the thermal nature parameter of the decarburization process by using CO-rich process gas. The endothermic Boudouard reaction (C + CO2 → 2CO) absorbs heat during carbon removal, converting the process from exothermic to endothermic, thereby achieving both high productivity and simplified temperature control
Solution Approach 2:
The invention converts the harmful exothermic heat generation into a beneficial endothermic cooling effect. By using CO and CO2 in the process gas, the decarburization reaction becomes endothermic, absorbing excess heat from the melt and maintaining optimal temperature without requiring additional cooling measures
3Temperature
If carbon dioxide is blown into the molten metal, then endothermic decarburization occurs and mixing is enhanced, but the volume expansion may cause operational challenges
Solution Approach 1:
The invention optimizes the CO2 concentration parameter within the range of 10-50 vol% in the process gas mixture. This parameter optimization ensures sufficient endothermic cooling effect while limiting excessive volume expansion, making the process easier to control operationally
Solution Approach 2:
The invention uses CO as an intermediary substance in the gas mixture. CO serves as both a reducing agent for slag/oxide removal and a precursor for the Boudouard reaction. Its presence moderates the direct impact of CO2 volume expansion while maintaining the endothermic cooling effect and enhancing overall process control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides an economical alternative with increased metal recovery, efficient slag reduction, and reduced operating time in steel production by leveraging the endothermic and exothermic properties of the Boudouard reaction and the resulting carbon monoxide.
Implementation Method 1
carbon dioxide (CO2) is reacted with carbon (C) to form carbon monoxide (2 CO)... during the course of the endothermic Boudouard reaction
Implementation Method 2
the three essential reactions occurring when using the method according to the invention, namely decarburization, desiliconization and dephosphorization of the carbon-containing molten metal are strongly endothermic, the carbon dioxide and the carbon monoxide formed are suitable as cooling gases
Implementation Method 3
a highly efficient reduction of oxides contained in the slag on the molten metal by the resulting and/or dissolved CO during CO2 blowing
Implementation Method 4
The product gas or reaction gas carbon monoxide (CO) takes up twice the volume compared to the carbon dioxide volume introduced or blown into the melt as reaction gas or reactant gas and thereby increases the strong melt mixing
Implementation Method 5
by the resulting and/or dissolved CO during CO2 blowing
Data Source
AI summary
The invention relates to a method for metallurgical treatment of a carbonaceous metal melt during a manufacturing process, in particular during a metallurgical final treatment process or final treatment step, by means of a process gas incorporated, in particular blown, onto and/or into the metal melt, wherein a method for metallurgical treatment of a carbonaceous metal melt is improved. Said improvement is achieved in that carbon dioxide (CO2) is blown onto and/or into the metal melt, as a process gas, and is at least partially converted to carbon monoxide (CO) as a product gas in the process of the endothermic Boudouard reaction with the carbon present in, in particular released in, the metal melt.