Impact of Hydrogen DRI on EAF Steelmaking, MIDREX

Impact of hydrogen DRI on EAF steelmaking, MIDREX.

The world steel industry constitutes 8% of the overall energy demand whilst contributing 7% of the total carbon dioxide (CO₂) generated by humanity (2.6 GTonne [GTe] CO₂ 2020; 2.8 GTe CO₂ 2015) [^{(1, 2)}, Figure 1].

The great majority of this CO₂ generation is due to coal, constituting 75% of the energy used in the steel industry, predominantly in the ironmaking process, where carbon is used chemically to reduce iron oxide and provide fuel for the process.

In the case of the Iron Blast Furnace, carbon (in the form of coke) also plays a vital role by providing structure and mechanical support to the bed of materials in the reactor shaft.

Figure 1 summarizes the generation and required CO₂ reductions, the anticipated increase in steel demand, and the required change in carbon intensity between 2015 and 2050⁽³⁾.

The massive potential generation of CO₂ from industrial processes and transportation is the motivation behind the desire to decarburize and become a Hydrogen Economy (using H₂ as a fuel source). This, of course, assumes cheaper and ‘greener’ methods of H₂ production become reality.

In the case of shaft furnace-based direct reduction (DR) processes, such as MIDREX®, a reducing gas mixture of carbon monoxide (CO) and H₂ is produced from the decomposition of natural gas.

Carbon does not play a key role in the process; however, increasing the H₂-to-CO ratio does have a significant effect on the process heat balance. In fact, there is substantial evidence that carbon can be removed from the process and replaced by H₂, as was discussed in the first quarter 2020 issue of Direct from Midrex ⁽⁴⁾.

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Impact of Hydrogen DRI on EAF Steelmaking, June 2021