摘要
为在分子水平上揭示低阶煤孔隙结构对其润湿性的影响,通过对具有不同孔隙结构的低阶煤模型进行巨正则蒙特卡洛运算探究了水分子在孔隙中的吸附特点,并对上述过程得到的最稳定的低阶煤-水构型进行分子动力学模拟研究了孔隙水的微观特性.结果表明:水分子以团簇形式吸附聚集于低阶煤孔隙中,团簇尺寸随孔隙率变小而减小;同一孔隙模型对水分子的吸附是等价的,不存在吸附差异明显的吸附区域;吸附过程符合二级动力学方程,且能用Langmuir等温吸附模型更好地描述.与体相水相比,孔隙水的扩散能力明显减弱;孔隙水中H和O的排列情况没有发生变化,但排列有序性增强,孔径越小,排列越紧密;水分子与低阶煤的相互作用强度随孔隙率变小而减弱,但单个水分子与低阶煤的相互作用强度则相反.同等孔隙率下,含氧比例低的模型对水分子的吸附强度减弱.研究结果给出了低阶煤孔隙吸附水分子的微观机理,解释了孔隙润湿效应弱化途径的原理,为低阶煤浮选中孔隙润湿效应弱化方法的选择提供了理论依据.
In order to reveal the effect of pore structure on the wettability of low-rank coal, low-rank coal models with different pore structures were constructed and the adsorption behaviors of water on these models were investigated using Grand Canonical Monte Carlo simulation(GCMC). Also, the properties of pore water were discussed by conducting the molecular dynamics simulation of low-rank coal-water configurations with lowest energy from GCMC simulation. The results indicated that water molecules were adsorbed and aggregated on pore in cluster form. As the decrease of aperture of low-rank coal, the size of the water cluster decreased and eventually behaved no longer in the form of cluster. The adsorption process of water on pore could be fitted by second-order kinetic equation, and it could be described through Langmuir adsorption model better. In the same low-rank coal pore model, the adsorption of water molecules by the pores was equivalent, and there were no multiple adsorption areas with obvious differences in adsorption strength. It was found that the diffusion ability of pore water was weakened significantly as a result of the attraction of oxygen-containing groups and the binding effect of pore compared with bulk water. The atomic arrangement of pore water was the same as that of pure water while the orderliness of pore water was strengthened. The smaller the pore size, the tighter the arrangement is. The interaction strength of water and low-rank coal models was weakened with the decrease of porosity, but the interaction strength between a single water molecule and low-rank coal was opposite. Under the same porosity, the model with low oxygen content weakens the adsorption strength of water molecules. The micro-mechanism of the adsorption of water in pore was provided and the molecular-level explanations about the methods to decrease the effect of pore on the wettability were given. It may provide a theoretical basis for the selection of the method of weakening the pore wetting effect in low-rank coal flotation.
作者
张雷
郭建英
栗褒
刘生玉
ZHANG Lei;GUO Jianying;LI Bao;LIU Shengyu(College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2022年第6期1117-1127,1192,共12页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(21878211)。
作者简介
通信作者:刘生玉(1969-),男,山西省临县人,教授,博士生导师,工学博士,从事界面分选理论、低值与固废资源加工利用方面的研究。E-mail:liusytyut@.126.com,Tel:15803439828。
