Direct Reduced Iron Carburization via Bosch Reaction

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Solution Overview

Problem

Existing direct reduction processes for iron ore produce direct reduced iron with a low carbon content and result in significant CO2 emissions, which are environmentally harmful.

Innovation Solution

A process that involves passing iron ore through a reduction zone using a high hydrogen content reduction gas to produce direct reduced iron with low carbon content, followed by a cooling zone where a cooling gas mixture of H2 and CO2 with a specific ratio is used to carburize the direct reduced iron, thereby increasing its carbon content while consuming CO2.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If hydrocarbons (e.g., methane) are used as cooling gas and reduction gas to increase carbon content of direct reduced iron, then carbon content is improved, but CO2 emissions increase significantly

Engineering Contradiction:

Improvecarbon contentVSAvoidCO2 emissions

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the cooling gas from hydrocarbon-based to a mixture of H2 and CO2 with specific ratios (H2:CO2 > 1.8). This parameter change enables the Bosch reaction to occur, where CO2 is consumed rather than produced, while still achieving the desired carbon content in the direct reduced iron through in-situ carburizing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts CO2 from a harmful emission into a useful reactant. By using CO2 as part of the cooling gas mixture, the process transforms CO2 into carbon through the Bosch reaction (CO2 + 2H2 → C + 2H2O), which then carburizes the direct reduced iron. This converts a greenhouse gas into a beneficial carbon source.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Quantity of substance

If hydrocarbons are used as cooling gas to carburize direct reduced iron, then carbon content is increased, but fossil fuel consumption increases

Engineering Contradiction:

Improvecarbon contentVSAvoidfossil fuel consumption

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent enables the system to serve itself by using the CO2 produced during the reduction process as part of the cooling gas mixture. This CO2, which would normally be wasted, is instead utilized in the Bosch reaction to generate carbon for carburizing the direct reduced iron, creating a self-sufficient carbon source that eliminates the need for external fossil fuel inputs.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent recovers CO2 that would otherwise be discarded as a byproduct of the reduction process. By incorporating CO2 into the cooling gas mixture and utilizing it in the Bosch reaction, the process transforms a waste stream into a valuable carbon source, eliminating the need to discard or purchase additional carbon-containing materials.

Inventive Principle:

Principle #34Discarding and recovering

3Productivity

If CO2 is produced as a by-product in direct reduction processes, then reduction reaction proceeds, but environmental harm increases

Engineering Contradiction:

Improvereduction efficiencyVSAvoidCO2 emissions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful CO2 byproduct into a beneficial carbon source. By incorporating CO2 into the cooling gas mixture with H2, the process enables the Bosch reaction to occur, transforming CO2 emissions into carbon that carburizes the direct reduced iron, thereby eliminating the environmental harm while maintaining productivity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the fate of CO2 by adjusting the process parameters - specifically the composition of the cooling gas and the temperature conditions in the cooling zone. These parameter changes enable CO2 to react with H2 via the Bosch reaction, converting it from a harmful emission into a useful carbon source for carburizing.

Inventive Principle:

Principle #35Parameter changes

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 process effectively increases the carbon content of direct reduced iron to suitable levels for further processing, while reducing CO2 emissions and minimizing the use of fossil fuels.

Implementation Method 1

The so-called Bosch reaction then takes place in the cooling zone: CO2+2H2→C+2H2O

Methodology Applied

Scientific EffectBosch reaction: Chemical Bonding

Implementation Method 2

The deposited carbon then reacts with the iron of the direct reduced iron to form Fe3C (cementite). In particular, the deposited carbon diffuses into the interior of the iron

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS12286679B2Method for the direct reduction of iron ore

Publication Date: 2025.04.29 THYSSENKRUPP STEEL EUROPE AG PATENTE PATENT DEPARTMENT

AI summary

The invention relates to a process for direct reduction of iron ore to afford direct reduced iron, wherein the iron ore sequentially passes through a reduction zone for reducing the iron ore to direct reduced iron and a cooling zone for cooling the direct reduced iron, wherein in the reduction zone the iron ore is subjected to a flow of a reduction gas and wherein in the cooling zone the direct reduced iron is subjected to a flow of a cooling gas. The cooling gas in the cooling zone comprises H2 and CO2, wherein the ratio of the mole fractions of H2 to CO2 is greater than 1.8 and the mole fraction of CO2 is greater than 20 mol %.