低阶煤反浮选中药剂共吸附行为及铵盐与矿物相互作用分子动力学研究

The separation of low rank coal has become a research focus recently. Reverse flotation method, which could take advantage of low rank coal’s high hydrophilicity, was introduced and could reduce low rank coal slime’s ash efficiently. But the action mechanism between reagents and minerals has not been identified. In this project, we will combine the bench-scale experiments, theoretical analysis and molecular dynamics simulation together, starting from adsorption theory, to explore the dynamic adsorption process of reagents, build the coadsorption matching model between coal surface structure and reagents, and analyze the interaction mechanism between reagents and minerals. Microcalorimetry would be adopted to measure the adsorption thermodynamical functions of amine on mineral surface, including the adsorption heat, adsorption entropy and gibbs free energy, etc., calculate the kinetic parameters of reagent adsorption, and build the absorption thermodynamics/dynamic models. Molecular dynamics simulation method would be used to simulate the process of amine overcoming the hydration shell on mineral’s surface as well as the interaction process of different mineral molecular structure and amine, to reveal the adsorption mechanism of amines on different minerals. This research will provide important theoretical guidance for the production application of low rank coal reverse flotation.

低阶煤煤泥洗选问题成为近年来的研究热点。充分利用低阶煤亲水性强的优势，采用反浮选方法对其进行分选回收，能显著降低低阶煤煤泥灰分。但药剂与矿物之间的作用机制尚不明确。本项目拟采用实验室试验、理论分析和分子动力学模拟相结合的研究手段，从吸附理论入手，采用石英晶体微天平（QCM-D）探测药剂在矿物表面的动态吸附过程，建立煤表面空间结构与药剂共吸附匹配模型，分析药剂与矿物的相互作用机制；采用微量热技术，测试铵盐在矿物表面的吸附热、吸附熵、吉布斯自由能等热力学函数，计算铵盐吸附动力学参数，建立吸附热/动力学模型；借助分子动力学模拟方法，模拟铵盐克服矿物表面水化层的过程以及不同矿物分子结构与铵盐相互作用过程，从微观层面揭示不同矿物对铵盐的吸附机制及差异，为低阶煤反浮选工艺的生产应用提供重要的理论指导。

通过吸附试验及分子动力学模拟对低阶煤反浮选过程中药剂在矿物表面的作用过程及捕收剂和抑制剂的协同作用进行研究。通过吸附试验，发现阳离子铵盐对石英和次烟煤表面性质的改变程度和吸附量大小没有关系，糊精的加入可以在一定程度上抑制石英和次烟煤对铵盐的吸附。相互作用能计算发现在抑制剂糊精的存在下，三种捕收剂(DTAB、TTAB和CTAB)与石英（100）和低阶煤表面的相互作用能均降低，与吸附试验结果对应。通过吸附形貌分析，发现抑制剂糊精的存在，石英分子和低阶煤与DTAB、TTAB、CTAB三种捕收剂分子之间的吸附作用降低，吸附形貌相对变松散。通过吸附浓度分析，可以看出加入捕收剂铵盐分子后，矿物表面附近的水溶液浓度明显下降，也就是水化膜变薄。通过均方位移的计算，可以看出在加入糊精前或者加入后，3种捕收剂铵盐在石英上的扩散更容易发生一些，也就是说捕收剂与石英的作用更加紧密。