| Coal is the base energy of China's energy structure,how to sealing the coal mine gas effectively is the priority work to the coal mine safe production.The gas sealing material of coal mine can prevent gas escaping from coal wall effectively and improve the coal mine safety production conditions.However,the current mainstream gas sealing products cannot meet the application requirements in coal mine complex environment,so the more economic,safe and effective gas sealing material still need to further developed.In addition,due to the strong hydrophobicity of coal wall and powder dispersion stability is bad of the material,the gas sealing effect in practical application will be affected.This paper first utilize of the performance advantage of ultra-fine fly ash(UFA),and coupled with organic emulsion,developed a new gas sealing material.The effect of UFA on the material of comprehensive gas plugging performance was explored.By introduce auxiliary functions,in-depth analysis the consumption optimization mechanism of foaming agent and dispersant on the plugging properties of composite gas.In addition,according to the shortcomings of the existing air tightness detection method of sealing material,this paper also puts forward a suitable air tightness detection method.The main research contents are as follows:(1)After studying on the influence of different percentages of ultra-fine fly ash on the comprehensive property of seal coating,the optimal amount of ultra-fine fly ash is determined as 60%.The water absorption of the seal coating after 7d is 5.0%.Its original tensile strength is 3.09 MPa.The elongation at break is 80%,and the bonding strength is 0.72 Mpa,up to the level II standard of GB/T23445-2009 polymer cement water proof coating.The flame retardant property and antistatic property is up to the safety standard for gas-sealing materials of underground coal mine of MT113-1995.Scanning electron microscopy and air tightness tests show that this material has a compact pore structure with good air tightness,and can be used as gas seal coating for underground coal mine.The addition of UFA,not only improved the performance of coal mine underground wall gas sealing material,but also reduced the cost of raw materials greatly,to provide a new way for the comprehensive utilization of fly ash.(2)The powder dispersion behavior influenced by dispersant six partial sodium phosphate(SHMP)were researched by the determination of Zeta potential,particle size analysis,IR and SEM-EDS.By using,In order to exploring the mechanism of SHMP on the typical powder material such as UFA,carbon black and graphite in the system,the DLVO theory was used and the interaction energy between particles were calculated.The surface hydrophobic effect of graphite and carbon black is the main factor of agglomeration.The dispersant SHMP can increase the interparticle electrostatic repulsion and steric hindrance,preventing agglomerate of the powder particles,which can also ensure the long time stable dispersion,provides a theoretical reference for the sealing material gas plugging performance improvement in the process of practical application.(3)Through the determination of different defoamer effect on the contact angle between gas sealing material and coal,the contact angle reduction effect of three butyl phosphate(TBP)is not affected by the concentration of emulsion material basically and the reduce rate of up to 30%~40%,which effectively improved the wettability of coal wall material on the coal surface.The material microstructure,bond strength,air tightness and the micro combination between material and coal were explored with TBP as the preferred defoamer agent.The results showed that the addition of TBP can optimize the micro morphology,microstructure and improve the gas sealing performance of material.At the same time,TBP also can make the material and the coal wall bond at the contact interface more closely,and achieve the effective permeability in coal samples,so as to enhance the comprehensive gas plugging effect effectively in the application process.(4)By independent design air tightness tester of gas sealing material,can realizes the simulation of coal mine gas emission testing environment.The test device has the advantages of small volume,low equipment investment,simple operation and reliable data.With compared to the market tightness test fee of film and sheet material,the detection cost is low and it also very suitable for coal wall coatings in laboratory testing.This paper takes UFA as the main raw material powder and developed a new type of gas sealing material,the material has good mechanical properties and excellent air tightness characteristics,which make up for the related materials and provides a new way for the utilization of fly-ash.Through the function additives introduced,the dispersion stability and wettability of material were improved effectively,which can ensure the comprehensive gas plugging performance of the new gas sealing material in actual application. |
PDF Full Text Request