TY - JOUR
T1 - Microwave-assisted self-reduction of composite briquettes of zinc ferrite and carbonaceous materials
AU - Ye, Qing
AU - Li, Guanghui
AU - Peng, Zhiwei
AU - Lee, Joonho
AU - Lin, Xiaolong
AU - Rao, Mingjun
AU - Zhang, Yuanbo
AU - Jiang, Tao
N1 - Funding Information:
This work was partially supported by the National Natural Science Foundation of China under Grants 51774337, 51504297, 51811530108, and 51881340420, the Science and Technology Major Project of Gansu Province, China, under Grant 1602FKDC007, the Innovation-Driven Program of Central South University under Grant 2016CXS021, the Shenghua Lieying Program of Central South University under Grant 502035001, the Natural Science Foundation of Hunan Province, China, under Grant 2017JJ3383, the Hunan Provincial Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources under Grant 2014-405, the Fundamental Research Funds for the Central Universities of Central South University under Grant 2018zzts222, and the Open-End Fund for the Valuable and Precision Instruments of Central South University under Grant CSUZC201706.
Funding Information:
This work was partially supported by the National Natural Science Foundation of China under Grants 51774337 , 51504297 , 51811530108 , and 51881340420 , the Science and Technology Major Project of Gansu Province , China, under Grant 1602FKDC007 , the Innovation-Driven Program of Central South University under Grant 2016CXS021 , the Shenghua Lieying Program of Central South University under Grant 502035001 , the Natural Science Foundation of Hunan Province , China, under Grant 2017JJ3383 , the Hunan Provincial Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources under Grant 2014-405 , the Fundamental Research Funds for the Central Universities of Central South University under Grant 2018zzts222 , and the Open-End Fund for the Valuable and Precision Instruments of Central South University under Grant CSUZC201706 .
PY - 2019/1/15
Y1 - 2019/1/15
N2 - Microwave carbothermic reduction of zinc ferrite was studied based on self-reduction of briquettes composed of zinc ferrite and different reducing agents, including coke, coal and biochar, in a vertical microwave furnace from both thermodynamic and experimental perspectives. The thermodynamic analysis showed that zinc ferrite could be reduced using the carbonaceous materials in a temperature range of 910–1250 °C. The experimental results demonstrated that the reducing agents had distinct microwave absorption capabilities, confirmed by the comparisons of corresponding microwave penetration depths (Dp, in this study Dp,coke> > Dp,coal > Dp,biochar) and reflection losses (RL, in this study RLcoke> > RLcoal > RLbiochar) based on the microwave permittivity and permeability measurements. This finding was in agreement with their different roles in the reduction, which produced reduced briquettes and volatilized matters via a series of stepwise reactions. Compared with conventional reduction, it was also found that the presence of microwave led to a much higher reduction efficiency. The coke exhibited a much lower reduction efficiency than coal and biochar. This observation was more obvious in microwave-assisted reduction where the coal and biochar contributed to high iron metallization degree (97%) and reduction degree (above 99%) after reduction at 1050 °C for 15 min even with low fixed carbon contents. Further analysis of the phase composition and microstructure of the reduced briquettes obtained in microwave-assisted reduction showed that metallic iron particles were formed but aggregated in different morphologies, probably associated with the growth of the metallic particles adjacent to the residual carbonaceous reducing agents. Meanwhile, the analysis of the corresponding volatized matter revealed that it was mainly constituted by highly pure metallic zinc particles which presented a hexagonal structure. The results indicated that in comparison with coke, the other two carbonaceous materials, especially biochar, could serve as more efficient and environmentally friendly reducing agents for treatment of zinc ferrite and zinc-bearing materials by its combined usage with microwave external field.
AB - Microwave carbothermic reduction of zinc ferrite was studied based on self-reduction of briquettes composed of zinc ferrite and different reducing agents, including coke, coal and biochar, in a vertical microwave furnace from both thermodynamic and experimental perspectives. The thermodynamic analysis showed that zinc ferrite could be reduced using the carbonaceous materials in a temperature range of 910–1250 °C. The experimental results demonstrated that the reducing agents had distinct microwave absorption capabilities, confirmed by the comparisons of corresponding microwave penetration depths (Dp, in this study Dp,coke> > Dp,coal > Dp,biochar) and reflection losses (RL, in this study RLcoke> > RLcoal > RLbiochar) based on the microwave permittivity and permeability measurements. This finding was in agreement with their different roles in the reduction, which produced reduced briquettes and volatilized matters via a series of stepwise reactions. Compared with conventional reduction, it was also found that the presence of microwave led to a much higher reduction efficiency. The coke exhibited a much lower reduction efficiency than coal and biochar. This observation was more obvious in microwave-assisted reduction where the coal and biochar contributed to high iron metallization degree (97%) and reduction degree (above 99%) after reduction at 1050 °C for 15 min even with low fixed carbon contents. Further analysis of the phase composition and microstructure of the reduced briquettes obtained in microwave-assisted reduction showed that metallic iron particles were formed but aggregated in different morphologies, probably associated with the growth of the metallic particles adjacent to the residual carbonaceous reducing agents. Meanwhile, the analysis of the corresponding volatized matter revealed that it was mainly constituted by highly pure metallic zinc particles which presented a hexagonal structure. The results indicated that in comparison with coke, the other two carbonaceous materials, especially biochar, could serve as more efficient and environmentally friendly reducing agents for treatment of zinc ferrite and zinc-bearing materials by its combined usage with microwave external field.
KW - Biochar
KW - Composite briquettes
KW - Dielectric loss
KW - Microwave
KW - Zinc ferrite
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U2 - 10.1016/j.powtec.2018.09.091
DO - 10.1016/j.powtec.2018.09.091
M3 - Article
AN - SCOPUS:85054464294
SN - 0032-5910
VL - 342
SP - 224
EP - 232
JO - Powder Technology
JF - Powder Technology
ER -