Steel is the backbone of the modern society. Although it is a key enabler of sustainability, its primary synthesis route is a heavy CO2 emitter. With about 2.1 tons of CO2 emitted per each ton of produced steel, ironmaking sector alone is responsible for ~7% of all CO2 emission on the planet. This is because the current technologies to extract iron from its ores use carbon-carrier substances as a reducing agent, a fact that leads CO2 as the by-product. On average, each ton of produced crude steel emit about 2.1 tons CO2. To fight global warming, the most polluting sources must be tackled, especially the steel manufacturing sector [1].

Reduction of iron ores with hydrogen plasma offers an attractive alternative to produce iron sustainably, as the direct by-product of the process is water [2,3]. In this route, a lean hydrogen-containing arc plasma is ignited between the electrode of an electric arc furnace (EAF), slightly modified to support small partial pressures of hydrogen (e.g. 10%H2), and the ore to be processed. During the process, both melting and reduction occurs simultaneously. This means that liquid iron is produced from its ores in one single step. In this lecture, the fundamental aspects of the hydrogen plasma reduction (HPR) will be presented and discussed, with focus on the chemical evolution (in part down to atomic scale) and phase transformations of the processed ores.

References

[1] D. Raabe, C. C. Tasan, E. A. Olivetti. Nature, 2019, 575 (7781), 64-74.

[2] I. R. Souza Filho, Y. Ma, M. Kulse, D. Ponge, B. Gault, H. Springer, D. Raabe. Acta Materialia, 2021, 213, 116971.

[3] I. R. Souza Filho, H. Springer, Y. Ma, A. Mahajan, C. C. Silva, M. Kulse, D. Raabe. Journal of Cleaner Production, 2022, 340, 130805.