Suppression Characteristics Of Silicate Mineral Powders On Methane Explosion

Methane explosion is one of the major disasters,and which seriously affects the safe production of coal industry.Therefore,it is great significance to research and development some suppression material of gas explosion to reduce hazards of gas explosion.In recent years,researchers have made some progress in the study of suppression technology and materials for gas explosion.Different types of suppressant are used in the field of gas explosion suppression.Due to the advantages of easy to obtain,low-cost and significant effects of suppression explosion,powder materials have become a new research hotspot in recent years.Silicate powders with properties that are rich source,low cost,small particle size,porosity and layered chain structure can be used as suppression explosion powders.In this paper,three types of silicate powders of the palygorskite,montmorillonite and surface modified palygorskite were seleced herein.The composition,pore structure,thermal properties and surface fuctional groups of the three powders were characterized by the X-ray diffractometry,automatic specific surface and pore size distribution analyzer,and fourier transform infrared spectrometer.The results showed that the silicate powders had mesoporous structure and good endothermic characteristics.More hydroxyl functional groups were hung on the surface of palygorskite modified by citric acid,and it had larger specific surface area and higher heat absorption than unmodified palygorskite.Secondly,the effects of different concentrations of silicate powders on methane-air premixed gas explosion pressure,pressure rise rate,the time of reaching the pressure peak and the average velocity of flame propagation was tested by using the 20 L spherical explosion instrument and the self-modified pipeline experimental system.The results showed that palygorskite and montmorillonite powders both had good inhibitory effect.In the 20 L spherical explosion instrument,when the mass concentration of palygorskite powder at 0.2 g/L is the best inhibitory effect on the 9.5% methane-air premixed gas explosion.Among them,the maximum pressure of methane explosion was dropped from 0.674 MPa to 0.509 MPa,decrease of 24.5%;the time of reaching the pressure peak was delayed from 0.071 s to 0.219s;the pressure rise rate was decreased from 34.471 MPa/s to 6.793 MPa/s.The montmorillonite powder had the best inhibitory effect when its mass concentration was 0.16 g/L.Among them,maximum pressure of methane explosion was dropped to 0.447 MPa,decrease of 29.2%;the time of reaching the pressure peak was delayed to 0.244 s;the pressure rise rate was decreased to 5.625 MPa/s.In the self-modified pipeline experimental system,the time of explosion flame propagation to the top of the pipeline was 38,61.5,58,77 ms when not powder was added and montmorillonite,palygorskite and modified palygorskite with a mass concentration of 0.24 g/L were added.When the flame propagates for 38 ms,the mass concentration of montmorillonite powder was 0.20g/L,the propagation distance of explosion flame was 0.094 m,which was only 20% of non-addition powder;the propagation distance of explosion flame was 0.194 m after adding the mass concentration of palygorskite was 0.24g/L,which was only 40% of non-addition powder.Finally,the mechanism of suppressing methane explosion of silicate powder was analysed based on the explosion thermal reaction mechanism and chain reaction mechanism,combined with the structural characteristics and thermodynamic properties of the material and analyzed from the physical inhibition and chemical inhibition.