University of Oulu

Pauna, H., Ernst, D., Zarl, M., Aula, M., Schenk, J., Huttula, M., & Fabritius, T. (2022). Hydrogen plasma smelting reduction process monitoring with optical emission spectroscopy – Establishing the basis for the method. Journal of Cleaner Production, 372, 133755.

Hydrogen plasma smelting reduction process monitoring with optical emission spectroscopy : establishing the basis for the method

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Author: Pauna, Henri1; Ernst, Daniel2; Zarl, Michael3;
Organizations: 1Process Metallurgy Research Unit, P.O. Box 4300, FI-90014, University of Oulu, Finland
2Department of Metallurgy, Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, 8700, Leoben, Austria
3K1-MET GmbH, Stahlstraße 14, A-4020 Linz, Austria
4Nano and Molecular Systems Research Unit, P.O. Box 3000, FI-90014, University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 12.2 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-10-26


In the world of ever-increasing demand for carbon-free steel, hydrogen and recycling have an undeniable role in achieving net-zero carbon dioxide emissions for the steel industry. However, even though steel is one of the most recycled materials globally, the quantity of steel that can be made from recycled steel will probably not match the demand in the future. This in turn means that steel must be also produced from the conventional resource, the iron ore. Hydrogen has been proposed as an environmentally friendly alternative to carbon as a reducing agent. To tackle the problems related to the usage of hydrogen for this purpose, hydrogen plasma smelting reduction has been studied extensively in the last few years. This article aims to provide means for process control of the hydrogen plasma, which may show erratic and chaotic behavior during the smelting process. The method used is optical emission spectroscopy, with which the plasma can be characterized, its composition can be evaluated, and its temporal evolution can be assessed. This study sheds light on how the plasma behaves with different electrode gaps and flow gas compositions together with how the position of the arc with respect to the center of the crucible can be assessed. In Ar/H₂ plasma, the plasma temperatures derived with OES varied between 4000 and 10000 K, and up to a 26% decrease in electron density was observed when increasing the electrode gap in 1 cm increments.

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Series: Journal of cleaner production
ISSN: 0959-6526
ISSN-E: 1879-1786
ISSN-L: 0959-6526
Volume: 372
Article number: 133755
DOI: 10.1016/j.jclepro.2022.133755
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work was supported by the Academy of Finland under the Genome of Steel grant No. 311934, Business Finland with the Towards Fossil-free Steel project No. 45774/31/2020, and the COMET program Fundamentals of hydrogen reduction, K1-MET project number 12204396. COMET is funded by the Federal Ministry 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). In addition, this work is partially financed by the industrial partners voestalpine Stahl GmbH and voestalpine Stahl Donawitz GmbH and the scientific partner Montanuniversitaet Leoben.
Copyright information: © 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (