University of Oulu

Omran M, Fabritius T, Heikkinen E-P, Chen G. 2017 Dielectric properties and carbothermic reduction of zinc oxide and zinc ferrite by microwave heating. R.Soc.opensci. 4:170710.

Dielectric properties and carbothermic reduction of zinc oxide and zinc ferrite by microwave heating

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Author: Omran, Mamdouh1,2; Fabritius, Timo1; Heikkinen, Eetu-Pekka1;
Organizations: 1Process Metallurgy Research Group, Faculty of Technology, University of Oulu, Oulu, Finland
2Mineral Processing and Agglomeration Laboratory, Central Metallurgical Research and Development Institute, Cairo, Egypt
3Key Laboratory of Unconventional Metallurgy, Kunming University of Science and Technology, Kunming, People’s Republic of China
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: Royal Society Publishing, 2017
Publish Date: 2018-02-16


This paper aims to study the dielectric properties and carbothermic reduction of zinc oxide (zincite, ZnO) and zinc ferrite (franklinite, ZnFe₂O₄) by microwave heating. To achieve this aim, the dielectric properties were measured with an open-ended coaxial method to understand the behaviour of the samples under microwave irradiation. The effects of microwave power, duration time and sample mass on the heating rate, and the effects of the stoichiometric amount of graphite on the reduction of ZnO and decomposition of ZnFe₂O₄ were investigated. The results show that ZnFe₂O₄ has significantly higher dielectric properties compared to ZnO. Generally, for both samples, the dielectric values at room temperature were quite low, indicating that both ZnO and ZnFe₂O₄ are poor microwave absorbers. It was found that the temperatures have a more significant effect on the imaginary permittivities than on the real permittivities. The heating rate showed that the sample temperature increased with increase in microwave power and sample mass. Using 700 W of microwave power and two times the stoichiometric amount of graphite, almost complete reduction of ZnO was achieved in 12 min, while ZnFe₂O₄ completely decomposed to zincite and wustite in 3 min.

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Series: Royal Society open science
ISSN: 2054-5703
ISSN-E: 2054-5703
ISSN-L: 2054-5703
Volume: 4
Issue: 9
Article number: 170710
DOI: 10.1098/rsos.170710
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
Copyright information: © 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License, which permits unrestricted use, provided the original author and source are credite