In this work, dielectric properties and thermochemical characteristics of mixtures of walnut shell and manganese ore were systematically investigated. Results indicated that reducing manganese ore by walnut shell was divided into four stages identified by temperatures: <150 °C, 150 °C–300 °C, 300 °C–480 °C, greater than 480 °C. Higher than 200 °C, the dielectric constants (εr′), dielectric loss factors (εr″)and loss tangent coefficients (tan δ)of mixture at a ore/biomass mixing ratio of 10:1.2 were observed to suddenly drop to low levels, with 5.107 (F/M), 8.5 × 10−4 (F/M), 1.66 × 10−4 (F/M), respectively; which were attributed to the MnO2 reduced by the reductive volatiles produced by biomass pyrolysis. Meanwhile, the volatiles rendered a decrease in density and dielectric properties of the mixture. The work highlights the possibility of reducing manganese ore by walnut shell with microwave heating.
Bibliographical noteFunding Information:
Financial supports from the National Scientific Foundation of China (No: U1802255), the Key Projects in the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period (No. 2015BAB17B00), the Hunan Provincial Science and Technology Plan Project, China (No. 2016TP1007), and Innovative Research Team (in Science and Technology) in University of Yunnan Province were sincerely acknowledged.
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- Dielectric properties
- Manganese ore
- Thermochemical characteristics
- Walnut shell