Molecular Simulation Research On The Spray Dust Reduction Mechanism Of Surfactant In The Underground Coal Mine

Mine dust prevention and control are closely related to the health of underground workers and the safety of coal mine production.Dust suppression by mist spray is one of the dust control measures widely adopted in China.The dust removal efficiency can be improved by adding surfactant into the spray dust removal liquid.It is helpful to reduce the blindness and complexity of macroscopic experiments to study the action mechanism of surfactant in the mine dust suppression process using the molecular dynamics method,which has good theoretical and practical significance.Based on this,this article used the cationic surfactants DTAB,anionic surfactant SDS,amphoteric surfactant BS-12,and non-ionic surfactant AEO-7 as the research object.Using molecular dynamics simulation,the application mechanism of surfactant in atomization,dust capture,and water retention in mine spray dust removal was systematically studied.Through the above research,it is expected to provide a micro theoretical basis for the application of surfactant in mine dust control.The main research conclusions are as follows:(1)Study on the influence mechanism of surfactant on spray atomization characteristics.The gas-liquid interface model of surfactant was established,and the interface configuration characteristics of surfactant molecules were obtained by using the molecular dynamics simulation method.The influence of surfactant on the particle size distribution of water mist was studied experimentally.The results show that the arrangement of surfactants at the gas-liquid interface is related to the relative number density of each component and the angular distribution of molecules,which is the reason for reducing the surface tension of the solution.The decrease of surface tension makes the surface area and particle size of droplets increase,thus improving the atomization effect.(2)Study on the influence mechanism of surfactant on the dust-catching ability of fog drops.The influence of surfactant on the adsorption characteristics of water on coal dust surface was studied through the natural water absorption experiment of coal dust and the coal wall model.The mechanism of influence of surfactant on the wettability of coal was discussed by using the electrostatic potential of molecular surface.The results show that the surfactant enhances the binding ability of water and coal dust,which is beneficial to the capture of coal dust particles by fog drops.After the coal molecules adsorb surfactant,by increasing the electric potential difference between coal molecules and H₂O molecules,the wettability of the coal surface is improved,and the dust catching ability of fog drops is enhanced.For lignite,bituminous,and anthracite,the addition of anionic surfactant SDS improved the droplet capture ability the most.(3)Water retention of surfactants and strengthening mechanism of inorganic salts.The solution model of the surfactant was constructed,and the distribution and interaction of H₂O molecules around the head group of the surfactant and the inorganic salt were obtained by using the molecular dynamics simulation method.Combined with the experiments,the water retentivity of the surfactant was verified.The results show that the surfactant plays a water-retaining role through the multi-layer hydration layer formed around the polar head group,and adding inorganic salts into the surfactant solution will have a more beneficial effect on the water-retaining effect of the dust removal solution.According to the disintegration energy barrier between the H₂O molecule and the surfactant head group,the water retention capacity of the four surfactant head groups was ranked as follows:SDS>BS-12>AEO-7>DTAB.(4)Experimental study on dust inhibition performance of surfactant.The dust removal effect of anionic surfactant SDS for different kinds of coal dust in the spray dust removal experiment was investigated by using the self-built spray dust removal experiment platform,and the optimal additive concentration of SDS was further determined.The results show that after adding SDS,the total dust removal rates of long-flame coal from Heidaigou,coking coal from Zhenchengedi,and anthracite from Yangmei increase to 94.57%,90.80%,and 87.96%,respectively.Under the experimental conditions,the optimal addition mass concentrations of SDS for these three kinds of coal dust are 0.2%,0.4%,and 0.3%,respectively.