Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, PR China.
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, PR China; Key Laboratory of Green-Chemistry Materials in University of Yunnan Province, Yunnan Minzu University, Kunming 650500, PR China.
Bioresour Technol. 2021 Jan;319:124172. doi: 10.1016/j.biortech.2020.124172. Epub 2020 Sep 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, M/M 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-16.69 kJ·mol and 0.0426 min-0.515 min. The work provides sound references for promoting the industrial application of the combined method on minerals reduction.
将生物质热解与微波加热技术相结合，为低品位软锰矿的还原提供了一种新颖、高效的方法。研究了核桃壳-软锰矿混合物的微波还原行为和热解动力学特性。结果表明，最佳还原参数为：还原温度 650℃，保温时间 30min，M/M 比为 1.8:10，微波功率为 1200W。混合物的共热解特性包括四个阶段：脱水、预热解、剧烈热解和还原、缓慢热解和还原。基于 Coats-Redfern 法的拟合分析表明，化学反应是生物质还原软锰矿过程的控制步骤，这一发现与通过未反应收缩核模型确定的等温动力学分析结果相吻合。确定了活化能和指前因子分别为 5.62 kJ·mol-1、6.69 kJ·mol-1 和 0.0426 min-1、0.515 min-1。这项工作为促进该联合方法在矿物还原方面的工业应用提供了可靠的参考。
