AUTHOR=Chen Jin , He Fei , Gao Lei , Guo Shenghui , Omran Mamdouh , Chen Guo 

TITLE=Rapid Preparation of Manganese Monoxide by Microwave-Enhanced Selective Carbothermal Reduction

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2022.845303

DOI=10.3389/fenrg.2022.845303

ISSN=2296-598X

ABSTRACT=Manganese has wide industrial applications, and a increasing demand of which is noticed in China where the high-grade manganese ore accounts for only 5% of the total available resources. Most of the manganese resource in China is exsited in a large number of low-grade pyrolusite which is waiting to be utilised and processed efficiently. The reason is because of the high energy consumption and environmental pollution during the reduction process of low-grade pyrolusite. Applying microwave heating to minerals reduction endows improved production efficiency and reduced production costs. In the present work, rapid preparation of manganese monoxide (MnO) was attempted through reducing low-grade pyrolusite with coal reducing agent by microwave heating, with the samples characterised by XRD, SEM, XPS as well as TG/DSC. The influences of the reduction reaction parameters on the reduction process of Mn in pyrolusite were comprehensively studied. The results indicating that higher temperatures and longer holding times facilitated the reduction roasting of pyrolusite, and manganese monoxide can be fabricated with a reduction ratio of 97.7% obtained at 650 °C for 50 min. The mechanism of the gradual transformation of MnO2 to MnO from the macroscopic to the molecular level was also revealed in the order of MnO2  Mn2O3  Mn3O4  MnO. Compared to traditional roasting, the proposed microwave-enhanced roasting process benefits from the superior kinetic conditions provided by synergy between microwave enhancement and compact pellets, and thus reduced the roasting temperature and roasting time.This research could provide a new theoretical foundation for promoting the industrialisation of microwave pretreatment of low-grade minerals.