University of Oulu

Kangqiang Li, Qi Jiang, Guo Chen, Lei Gao, Jinhui Peng, Quan Chen, Sivasankar Koppala, Mamdouh Omran, Jin Chen, Kinetics characteristics and microwave reduction behavior of walnut shell-pyrolusite blends, Bioresource Technology, Volume 319, 2021, 124172, ISSN 0960-8524,

Kinetics characteristics and microwave reduction behavior of walnut shell-pyrolusite blends

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Author: Li, Kangqiang1; Jiang, Qi1; Chen, Guo1,2;
Organizations: 1Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, PR China
2Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, Yunnan Minzu University, Kunming 650500, PR China
3Panjin Institute of Industrial Technology, Dalian University of Technology, Panjin 124221, Liaoning, PR China
4Process Metallurgy Research Group, Faculty of Technology, University of Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.8 MB)
Persistent link:
Language: English
Published: Elsevier, 2021
Publish Date: 2022-09-28


Combining biomass pyrolysis with microwave heating technologies provides a novel and efficient approach for low-grade pyrolusite reduction. The microwave reduction behavior and pyrolysis kinetic characteristics of walnut shell-pyrolusite blends were explored. Results indicated the optimal reduction parameters were: reduction temperature of 650 °C, holding time of 30 min, Mbio/More of 1.8:10, and microwave power of 1200 W. The co-pyrolysis characteristics of the blends included four stages: dehydration, pre-pyrolysis, intense pyrolysis and reduction, and slow pyrolysis and reduction. Fitting analysis based on Coats-Redfern method revealed that chemical reaction was the control step of the process of reducing pyrolusite by biomass, which the finding matched to the isothermal kinetic analysis results determined through unreacted shrinking nuclear model. The activation energies and pre-exponential factors were determined at 5.62 kJ·mol⁻¹–16.69 kJ·mol⁻¹ and 0.0426 min⁻¹–0.515 min⁻¹. The work provides sound references for promoting the industrial application of the combined method on minerals reduction.

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Series: Bioresource technology
ISSN: 0960-8524
ISSN-E: 1873-2976
ISSN-L: 0960-8524
Volume: 319
Article number: 124172
DOI: 10.1016/j.biortech.2020.124172
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: Financial supports from the National Natural Science Foundation of China (No: U1802255), and Innovative Research Team (in Science and Technology) in University of Yunnan Province were sincerely acknowledged.
Copyright information: © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license by