Study On Wettability Identification And Control Technology Of Water-Insoluble Coal Dust

With the continuous improvement of mechanized mining,coal dust hazard become increasingly prominent,and seriously affects the operation safty and workers' health.The inappropriate selection or design of control and removal systems at fully mechanized working face is the main reason for high dust concenteations in underground coal mines.In this paper,theoretical analysis,numerical simulation and experimental technologies were used for the study of the physic-chemical characters,the influencing factors of coal dust wettability,and estimation model of wetting contact angle,and the airflow pattern and moving rule of the particles,and the design and optimization of air curtain dust control system,and so on.By analyzing the influence of particles sizes and coal quality parameters to coal dusts wettability,the wetting contact angle has a rising tendency with the increasing degree of coalification.The oxygen,carbon and fixed carbon content have a greater impact on the coal dust wettability.According to the nonlinear relationship between coal dust wetting contact angle and its influence factors,coal quality parameters were input to construct a three layers BP artificial neural network model,which includes seven coal quality parameters through optimizing the network structure and parameters.Finally,the established model is applied to estimate coal dust wetting contact angle.This method can solve the problem of the complicated measurement of wetting contact angle on the solid surface.And then the grades of coal dust wettability classified by wetting contact angle were identified,the grades of coal dust wettability includes higher wettability,general wettability,bad wettability and unwettability.For controlling hydrophobic coal dust in fully mechanized working face,a new dust control methods using air curtain to collect dust and windsocks to draw out coal dust to the removal equipment,which is put forward according to the present situation of research.Reasonable distance between tunneling working face and forced ventilation were determined according to the simulation of gas-solid two-phase flow airflow pattern and moving rule of the particles.The space between the wind curtain and the suction inlet of the duster,the exit width of the wind curtain,and duster pressure were studied by analysis with velocity distribution of airflow,then the parameters of dust control and removal system were determined.The research demonstrate the dust removal effect of dust with dust control and the removal system with its curtain of 240° arc and the duster which has an obviously effect on reducing the dust concentration at fully mechanized working face,by means of field testing and numerical simulation analysis.Coal dust wetting contact angle and wettability classification results from BP neural network model can be used to guide the selection of effective dust-reducing measures for coal mine well.The results make great practical significance to study the new dust control and removal system for reducing the coal dust concentration at fully mechanized working face with water-insoluble coal dust.