Carbon-Enriched DRI Compaction for Lower-CO2 Iron Melting
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Solution Overview
Problem
Existing methods struggle to achieve a carbon content of at least 1.5% by weight in direct reduced iron (DRI) during direct reduction processes, leading to energy-intensive melting and increased CO2 emissions, particularly when using carbon-containing reducing gases or downstream carburization reactors, and compaction methods like HBI/HCl are costly and challenging due to density differences.
Innovation Solution
Introduce a solid carbon carrier, such as coke or biogenic carbon, into DRI outside the direct reduction unit, followed by compaction to form HBI/HCl, ensuring the carbon is evenly distributed and in close proximity to iron oxides for efficient reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-containing reducing gas is used in direct reduction, then carbon content in DRI increases, but CO2 emissions increase
Solution Approach 1:
The invention applies preliminary action by adding carbon carriers to DRI before compaction, preparing the material in advance for subsequent processing. This allows carbon to be introduced at an earlier stage rather than during melting, enabling better control over carbon content while using low-carbon reducing gases in the direct reduction process
Solution Approach 2:
The invention uses carbon carriers as intermediaries to transfer carbon to DRI. These carriers (such as coal powder, coke, or carbon black) serve as a mediating substance that can be easily added and distributed, providing a controlled method to increase carbon content without directly using carbon-containing reducing gases that would increase CO2 emissions
2Quantity of substance
If downstream carburization reactor is used to increase carbon content, then carbon content in DRI increases, but processing complexity and energy consumption increase
Solution Approach 1:
The invention merges the carbon addition step with the existing compaction process. By adding carbon carriers to DRI before compaction, the carbon introduction function is combined with the mechanical compaction operation that already exists in the process flow, eliminating the need for a separate downstream carburization reactor and reducing overall processing complexity
Solution Approach 2:
The compaction process is given multiple functions: it not only densifies the DRI material but also serves as the mechanism for introducing and distributing carbon carriers. This multi-functionality eliminates the need for dedicated carburization equipment, simplifying the overall process while achieving the desired carbon content
3Quantity of substance
If carbon carriers are added before compaction, then carbon content in DRI increases, but uniform distribution of carbon is challenging
Solution Approach 1:
The invention utilizes the porous structure of loose DRI material before compaction to facilitate carbon carrier distribution. The void spaces and porous nature of uncompressed DRI allow carbon carriers to penetrate and distribute more uniformly throughout the material matrix, ensuring better mixing before the compaction process densifies everything together
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
This approach enhances the carbon content in DRI, reducing energy consumption during melting, minimizing iron losses, and facilitating residual reduction of iron oxides, thus optimizing the processing efficiency and reducing CO2 emissions.
Implementation Method 1
at least one solid carbon carrier is added to the DRI
Implementation Method 2
after addition of the solid carbon carrier to the DRI, the DRI undergoes compaction
Implementation Method 3
The carbon provides for example chemical energy through gasification with oxygen, which can be utilized for the heating or reduction of iron oxides
Implementation Method 4
The carbon also helps lower the melting point of an iron melt, which makes melting less energy-consuming
Implementation Method 5
the carbon is used for the residual reduction of iron oxide in order to minimize losses of iron in the slag
Data Source
AI summary
A method for introducing carbon into direct reduced iron (DRI), wherein at least one solid carbon carrier is added to the DRI, and the DRI is hardened once the solid carbon carrier has been added to the DRI.