University of Oulu

Kallio R, Tanskanen P, Heikkinen E-P, Kokkonen T, Luukkanen S, Fabritius T. Slag Modification in Reduction of Kiviniemi Ferrous Scandium Concentrates. Metals. 2022; 12(5):709.

Slag modification in reduction of Kiviniemi ferrous scandium concentrates

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Author: Kallio, Rita1; Tanskanen, Pekka2; Heikkinen, Eetu-Pekka2;
Organizations: 1Oulu Mining School, Faculty of Technology, University of Oulu, FI-90014 Oulu, Finland
2Process Metallurgy Research Group, Faculty of Technology, University of Oulu, FI-90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 16.7 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2022
Publish Date: 2022-09-05


Several research projects are currently focused on the search for new sources of scandium due to its expected increasing demand in advanced technology applications. The Kiviniemi Fe-Sc-enriched mafic intrusion is a potential primary source for Sc. According to the recent investigations on the FeO component reduction in the Kiviniemi magnetic Sc concentrate at various end temperatures, complete FeO reduction is achieved at the highest experimental temperature (1500 °C). However, efficient separation of metal from the Sc₂O₃-enriched slag is hindered by the high viscosity of the slag. In this study, investigations of the Kiviniemi-type concentrate reduction characteristics are complemented from three perspectives: (1) slag modification with CaF₂ and/or CaO to promote the reduction of the FeO component and metal separation, (2) reduction characteristics of the concentrates with a slightly different modal mineralogy and chemical composition, and (3) description of the main features of the progression of reduction at selected temperatures (950, 1050, 1150, 1250, and 1350 °C) with CaO addition. Both CaF₂ and CaO increase conversion rates at a lower temperature region and promote the separation of metal from the slag. High-temperature behavior of the concentrates used in this study is essentially similar, although the main reduction stage is initiated at a slightly higher temperature for concentrates with less amphibole and a higher amount of nonferrous gangue minerals. Only after the complete decomposition and melting of clinopyroxene and nonferrous minerals of the concentrate, the final reduction of the FeO component from the slag can take place.

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Series: Metals
ISSN: 2075-4701
ISSN-E: 2075-4701
ISSN-L: 2075-4701
Volume: 12
Issue: 5
Article number: 709
DOI: 10.3390/met12050709
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
215 Chemical engineering
Funding: This research has been funded by The Foundation for Research of Natural Resources in Finland, grant number 20210019.
Copyright information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (