热活化焙烧—稀硫酸浸出贵州某煤矸石中的锂与铝

Leaching of Lithium and Aluminum from Guizhou Coal Gangue via Thermal Activation Roasting−Dilute Sulfuric Acid Process

  • 摘要: 为实现煤矸石的高附加值综合利用,为煤矸石资源化利用提供理论依据和技术支撑,以贵州西部某煤矿煤矸石为研究对象,根据煤矸石中锂、铝赋存特征,探索锂、铝浸出,提出了热活化焙烧—稀硫酸浸出工艺,考察了焙烧温度、焙烧时间、液固比、硫酸浓度、浸出温度、浸出时间对锂、铝浸出率的影响;并进一步探讨了锂、铝浸出机理;采用收缩未反应核模型对锂、铝协同浸出过程进行动力学分析。结果表明:在焙烧温度500 ℃、焙烧时间150 min、液固比4∶1、硫酸质量浓度15%、浸出温度80 ℃、浸出时间90 min的最佳条件下,锂浸出率达92.80%,铝浸出率达85.26%。煤矸石经500 ℃焙烧,高岭石转变为无序偏高岭石结构,反应活性显著增强。在硫酸提供的强酸性环境中,偏高岭石分解,逐渐生成可溶性的硫酸铝和硫酸锂进入溶液中。锂、铝协同浸出过程由化学反应控制,活化能分别为36.97和66.11 kJ/mol。

     

    Abstract: To achieve the high−value comprehensive utilization of coal gangue andprovide theoretical basis and technical support for its recycling, this investigation focuses on coal gangue from a coal mine in western Guizhou, China. Based on the occurrence characteristics of lithium and aluminum in the coal gangue, the leaching behaviors of lithium and aluminum was explored. A process involving thermal activation roasting followed by dilute sulfuric acid leaching was proposed. The effects of roasting temperature, roasting time, liquid−to−solid ratio, sulfuric acid concentration, leaching temperature, and leaching time on the leaching rates of lithium and aluminum were investigated. Furthermore, the mechanism of lithium and aluminum leaching was discussed. The unreacted shrinking core model was applied to analyze the kinetics of the synergistic leaching process. The results show that under the optimal conditions(roasting temperature of 500℃, roasting time of 150 min, liquid−to−solid ratio of 4∶1, sulfuric acid concentration of 15%, leaching temperature of 80℃, and leaching time of 90 min), the leaching rates of lithium and aluminum reach 92.80% and 85.26%, respectively. After roasting at 500℃, the kaolinite in the coal gangue transformed into disordered metakaolinite, enhancing its reactivity. In the strongly acidic environment provided by sulfuric acid, metakaolinite decomposes, gradually forming soluble aluminum sulfate and lithium sulfate, which enter the solution. The synergistic leaching process of lithium and aluminum is controlled by chemical reactions, with activation energies of 36.97 kJ/mol and 66.11 kJ/mol, respectively.

     

/

返回文章
返回