Effects of the Electrodes’ Shape and Graphite Quality on the Arc Stability During Hydrogen Plasma Smelting Reduction of Iron Ores

Daniel Ernst, Michael Andreas Zarl, Manuel Andreas Farkas, Johannes Schenk

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)


Reducing greenhouse gases (GHG), especially CO2, is necessary to counteract climate change. The European steel industry currently corresponds to 5.7% of the total EU emissions and must therefore minimize their GHG fractions in the future. One of the most promising technologies to eliminate CO2 emissions while directly reducing iron ore to steel in a single step is the hydrogen plasma smelting reduction. The stability of the plasma arc, which is determined by the properties and geometry of the graphite electrode, has a substantial impact on the process’ economic feasibility. To study the arc stability concerning the graphite quality, tip geometry, and electrode gap, a series of experiments is conducted. The results are evaluated to create stability maps and fields to identify stable process parameters. The geometry of the graphite cathode shows the primary influence on arc stability. Tips with a flat end (standard version) offering the most unstable and a machined step on the graphite cathode providing the most stable conditions. However, an additional coating to prevent side arcing leads to the deterioration of the arc. The two graphite grades tested, with different maximum grain sizes and price classes, show no great relevance to the stability of the arc.
Original languageEnglish
Article number2200818
Number of pages12
JournalSteel research international
Issue number7
Publication statusE-pub ahead of print - 9 Feb 2023

Bibliographical note

Funding Information: The authors gratefully acknowledge the SuSteel project's funding by The Austrian Research Promotion Agency (FFG) and the funding support of K1‐MET GmbH metallurgical competence center. The K1‐MET competence center's research program is supported by COMET (Competence Center for Excellent Technologies) and the Austrian program for competence centers. The Federal Ministry funds COMET for Climate Action, Environment, Energy, Mobility, Innovation and Technology, the Federal Ministry for Digital and Economic Affairs, the provinces of Upper Austria, Tyrol, and Styria, and the Styrian Business Promotion Agency (SFG).

Publisher Copyright: © 2023 The Authors. Steel Research International published by Wiley-VCH GmbH.


  • arc stability
  • electrode geometry
  • graphite
  • hydrogen plasma smelting reduction
  • hydrogen reduction
  • iron ore
  • plasma

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