Bu Xiangning, Tong Zheng, Bilal Muhammad, Ren Xibing, Ni Mengqian, Ni Chao, Xie Guangyuan
Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education), School of Chemical Engineering and Technology, China University of Mining & Technology, Xuzhou 221116, China.
Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education), School of Chemical Engineering and Technology, China University of Mining & Technology, Xuzhou 221116, China.
Ultrason Sonochem. 2023 May;95:106415. doi: 10.1016/j.ultsonch.2023.106415. Epub 2023 Apr 20.
This study aimed to investigate the effect of ultrasonic power and temperature on the impurity removal rate during conventional and ultrasonic-assisted leaching of aphanitic graphite. The results showed that the ash removal rate increased gradually (∼50 %) with the increase in ultrasonic power and temperature but deteriorated at high power and temperature. The unreacted shrinkage core model was found to fit the experimental results better than other models. The Arrhenius equation was used to calculate the finger front factor and activation energy under different ultrasonic power conditions. The ultrasonic leaching process was significantly influenced by temperature, and the enhancement of the leaching reaction rate constant by ultrasound was mainly reflected in the increase of the pre-exponential factor A. Ultrasound treatment improved the efficiency of impurity mineral removal by destroying the inert layer formed on the graphite surface, promoting particle fragmentation, and generating oxidation radicals. The poor reactivity of hydrochloric acid with quartz and some silicate minerals is a bottleneck limiting the further improvement of impurity removal efficiency in ultrasound-assisted aphanitic graphite. Finally, the study suggests that introducing fluoride salts may be a promising method for deep impurity removal in the ultrasound-assisted hydrochloric acid leaching process of aphanitic graphite.
本研究旨在探究超声功率和温度对隐晶质石墨常规浸出及超声辅助浸出过程中杂质去除率的影响。结果表明，随着超声功率和温度的升高，灰分去除率逐渐增加（约50%），但在高功率和高温下会下降。结果发现，未反应收缩核模型比其他模型更符合实验结果。利用阿伦尼乌斯方程计算了不同超声功率条件下的指前因子和活化能。超声浸出过程受温度影响显著，超声对浸出反应速率常数的增强作用主要体现在指前因子A的增加上。超声处理通过破坏石墨表面形成的惰性层、促进颗粒破碎和产生氧化自由基，提高了杂质矿物的去除效率。盐酸与石英及一些硅酸盐矿物反应活性较差，是限制超声辅助隐晶质石墨杂质去除效率进一步提高的瓶颈。最后，该研究表明，引入氟盐可能是超声辅助盐酸浸出隐晶质石墨过程中深度去除杂质的一种有前景的方法。
