Suppression Characteristics Of Red-mud Based Composite Powders With Core-shell Structure On Methane Explosion

Gas explosion is one of the major disasters in coal mine.Therefore,inhibition of gas explosion is an important issue that need to be resolved.In recent years,many experts and scholars have been committed to the study on explosion suppression technology and explosion suppression materials,and made some progress.Among many suppressants,the powder explosion suppression material is widely used in the field of gas explosion suppression because of its low cost,environmental protection and high efficiency.First of all,we prepared red mud based composite powder and study its physicochemical characteristics.In this paper we selects the industrial solid waste red mud as the base material,on the basis of the modified pretreatment.we selected BC powder（KHCO₃,NaHCO₃）and ABC powder（NH₄H₂PO₄）as the load component.The KHCO₃,NaHCO₃,NH₄H₂PO₄ were loaded on the red mud surface by using crystallization method.the NaHCO₃/red mud composite powder,KHCO₃/red mud composite powder and NH₄H₂PO₄/red mud composite powder were completed.The physicochemical property of composite powders were characterized by the X-ray diffractometer,JSM-6390LV Scanning Electron Microscope,Autosorb-iQ automatic specific surface and pore size distribution analyzer and STA449C Thermal Analyzer.The results indicated that three kinds of composite powders with red mud foundation support is consist of red mud foundation support and carriers.They have the“core-shell”structure with biggish specific area,and better endothermic character.The suppression property of three kinds of"core-shell"type composite powder with red mud foundation support for CH₄ explosion was tested by a 20 L spherical explosion experimental system and 5L pipeline explosion experimental system.The results show that three kinds of"core-shell"type composite powder with red mud foundation support showed good inhibitory effect.When the loaded content reach to30%,three kinds of"core-shell"type composite powder with red mud foundation support demonstrated the best inhibitory effect.Inhibition of NaHCO₃/red mud composite powder,KHCO₃/red mud composite powder and NH₄H₂PO₄/red mud composite powder were respectively showed on the maximum explosion pressure which is reached to 37.5%,40.4%,35.1%,inhibition of the maximum rate of pressure rise respectively reached 93.2%,94.1%,95.8%,arrived at the peak pressure of the delay time were 0.25s,0.28s,0.43s.Among them,30%NaHCO₃/red mud composite powder showed the best inhibition effect on pressure of explosion and maximum pressure rise rate,30%NH₄H₂PO₄/red mud composite powder showed the best inhibition effect on the optimal delay time to peak pressure.Finally,we discussed the suppression mechanism of the core-shell composite powder.The synergistic inhibition mechanism of composite powders was revealed from two aspects:physical inhibition and chemical inhibition.Which is based on the mechanism of thermal explosion reaction and the mechanism of chain reaction,combined with the structural and thermodynamic properties of the material.