Simulation Study On Interaction Between Coal And Montmorillonite In Coal Slurry

Coal slime suspension is referred to as coal slurry water.Coal slurry water treatment is an important part in wet coal preparation.The mechanization of coal mining is improved,the proportion of raw coal slime is increased,and the clay mineral represented by bentonite is in the process of washing and water.Contact expansion dissociation forms high muddy coal slurry water,covering the surface of coal particles,changing the physical and chemical properties of coal slurry water,seriously affecting the washing and recovery of fine-grained coal slurry.The formed high-sludge coal slurry has complex water composition,high viscosity,fine solid particle size,high ash content,strong water holding capacity and high viscosity,which makes the solid-liquid separation effect poor,the coal recycling water recycling rate is low,and the slime water treatment has become difficult,which has a great impact on the smooth progress of coal washing.The research on the interaction mechanism between mineral interfaces has important theoretical guiding significance for solving the problem of improving the efficiency of flotation and improving the treatment of coal slurry.In order to explore the interaction mechanism between coal and different minerals in coal slurry,this paper uses molecular dynamics simulation to study the interaction behavior of Wiser coal model in aqueous solution on the surface of quartz,kaolinite and montmorillonite mineral particles.The adsorption model of the Wiser bituminous molecular model in the aqueous solution system on the quartz surface,kaolinite(001)surface,kaolinite(001?)surface and montmorillonite(001)surface was simulated.Through the analysis of the interaction process between coal molecules and different minerals,it is known that coal molecules are easily adsorbed on the surface of quartz,kaolinite and montmorillonite minerals.The adsorption strength of kaolinite and montmorillonite minerals on coal is stronger than that of quartz minerals.The concentration distribution curve analysis of the equilibrium configuration of coal molecules with stable adsorption shows that the benzene ring and the oxygen-containing functional group in the coal molecule are more easily adsorbed on the surface of the mineral,and the functional groups such as the alkyl group are far away from the mineral surface.The complexity of coal water composition affects the cation exchange capacity of clay minerals.In order to explore the effect of cation exchange on the adsorption between montmorillonite and coal molecules,molecular dynamics method was used to study the different cation exchanges of Wiser bitumin model in simulated aqueous solution.The adsorption behavior of celite particles on the surface of CEC was constructed.The adsorption model of Wiser bituminous coal molecules on the surface of three different CEC montmorillonite particles in aqueous solution system was constructed.The parameters such as equilibrium configuration,concentration distribution curve and radial distribution function are analyzed.The results show that there is an interaction between the coal molecules and the montmorillonite particles in the solution,and the benzene ring and the oxygen-containing functional group in the coal structure have an important influence on the adsorption.With the enhancement of CEC of montmorillonite,the oxygen-containing functional groups in the bituminous coal molecules are more easily adsorbed on the(001)surface of montmorillonite,and the functional groups such as alkyl groups are farther away from the surface of montmorillonite,while CEC is contained in water molecules and bituminous coal molecules.The adsorption of oxygen functional groups has a certain promoting effect.The adsorption of bituminous coal molecules on different mineral surfaces is related to the functional groups of bituminous coal molecules.The adsorption on the mineral surface mainly interacts with the oxygen-containing functional groups and benzene rings on the coal surface.The density functional theory method based on quantum mechanics can penetrate from the atomic level.To study the electronic structure and properties of coal and montmorillonite surface interactions.Therefore,the density functional calculation of the adsorption behavior on the surface of montmorillonite(001)is carried out on six common functional building blocks representing the surface of coal: phenolic hydroxyl group,carboxyl group,carbonyl group,ether bond,alcoholic hydroxyl group and alkyl group.The adsorption of the bituminous coal functional group on the montmorillonite(001)layer was studied comprehensively from the aspects of adsorption configuration,adsorption energy,charge population,differential electron density and density of states.The interaction mechanism between bituminous coal molecules and montmorillonite particles.It is known that there is an interaction between the coal functional group structural unit and the montmorillonite particles.When the adsorption is stable,the coal functional group model molecules are parallel to the surface of the smectite,at the same time,the oxygen-containing group is slightly inclined to the surface,and the group such as an alkyl group deviates from the surface of the smectite.For the analysis of the adsorption distance and adsorption energy of the coal structural unit and the montmorillonite surface in the equilibrium configuration,it is known that the adsorption stability of different coal functional group units on the montmorillonite(001)surface is stronger than that on the surface of the water molecules.The adsorption stability of different coal structural units on the montmorillonite(001)surface is: meta-carboxy toluene > m-hydroxytoluene > cresol > acetophenone > phenyl ether > m-dimethyl benzene > water molecule.The results of frontier orbital analysis indicate that the oxygen-containing structural unit of coal easily reacts with montmorillonite.The frontier orbit of coal oxygen-containing structural unit mainly appears on the structure of benzene ring and functional group.The frontier orbit of montmorillonite mainly exists on the surface of silicon oxide.The enclosed oxygen ring orbit and the center of the ring.The results of charge transfer analysis show that there is a van der Waals interaction between the oxygen-containing structural unit of coal and montmorillonite.There is still a certain degree of electrostatic force on the surface of meta-carboxytoluene,mhydroxytoluene,cresol and montmorillonite.The differential electron density map and the partial wave density analysis also confirm the above conclusion from the perspective of electron density and electron valence band.