University of Oulu

Du, J., Gao, L., Yang, Y., Guo, S., Omran, M., Chen, J., & Chen, G. (2021). Dielectric characterisation and reduction properties of the blending mixtures of low-grade pyrolusite and waste corn stalks in the microwave field. Fuel, 305, 121546. https://doi.org/10.1016/j.fuel.2021.121546

Dielectric characterisation and reduction properties of the blending mixtures of lowgrade pyrolusite and waste corn stalks in the microwave field

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Author: Du, Jinjia1; Gao, Lei2; Yang, Yong3;
Organizations: 1Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
2Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, Yunnan Minzu University, Kunming 650500, China
3Daxin Branch of CITIC Dameng Mining Industries Ltd., Chongzuo 532315, China
4Faculty of Technology, University of Oulu, Finland
Format: article
Version: accepted version
Access: embargoed
Persistent link: http://urn.fi/urn:nbn:fi-fe2021081843560
Language: English
Published: Elsevier, 2021
Publish Date: 2023-07-30
Description:

Abstract

Recently, pyrometallurgical reduction of low-grade pyrolusite is one of the potential techniques for expanding the resources for manganese. However, the process has a high cost on fossil energy and produces a large amount of greenhouse gases. This work proposed a novel method of using biomass, namely corn stalks, to reduce and roast low-grade pyrolusite under microwave field to provide positive alternatives for fossil energy. The microwave-assisted reduction was studied systematically, and the corresponding mechanism was also studied by thermodynamic analysis and dielectric properties analysis. Results indicated that co-pyrolysis reduction characteristics of the mixtures were mainly divided into three stages: the pre-reaction stage (25 °C–196 °C), activated pyrolysis reduction stage (196 °C–480 °C), and carbonisation stage (>430 °C). The mechanism of MnO₂ reduction is attributed to reductive volatiles (H₂, CO, CH₄) and the fixed carbon (C) produced by biomass pyrolysis. Meanwhile, the reduction efficiency of Mn can achieve 97.2% at 650 °C for 60 min with 25% corn stalks, indicating efficient pyrolusite reduction by microwave heating. These results enrich the fundamental knowledge on the corresponding industrial technology development.

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Series: Fuel
ISSN: 0016-2361
ISSN-E: 1873-7153
ISSN-L: 0016-2361
Volume: 305
Article number: 121546
DOI: 10.1016/j.fuel.2021.121546
OADOI: https://oadoi.org/10.1016/j.fuel.2021.121546
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Subjects:
Funding: Financial supports from the National Natural Science Foundation of China (No: U1802255), and the Innovative Research Team (in Science and Technology) at the University of Yunnan Province were sincerely acknowledged.
Copyright information: © 2021 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/.
  https://creativecommons.org/licenses/by-nc-nd/4.0/