Study On Preparation And Characteristics Of Mine Fire Activated Fly Ash Colloid

China is a country with more coal and less oil.Coal resources have always been China's main energy structure.However,with the mining and development of coal resources,serious problems in the mining process have gradually been exposed,especially because of fires in coal mines.Increasing frequency of fires in mines poses a huge threat to the normal production and life of coal mines.In response to this serious coal spontaneous combustion fire,many methods are currently used in coal mines to control the spontaneous combustion of coal left in goafs,but the goal of suppressing spontaneous combustion of coal left in goafs is often not achieved.Fly ash is the fine particles produced after coal combustion,contains a large amount of oxides of silicon.Through the study of the elemental composition of fly ash and the inherent physical and chemical activity of fly ash It was found that the metal oxides in the fly ash mainly existed in a spatially interwoven network structure,which is not easy to react with acids.Therefore,sodium hydroxide was used to stimulate the activity of the fly ash.The excited fly ash solution contains a large amount of metal ions,And then use sodium carboxymethyl cellulose and metal ions in the fly ash activation solution to carry out graft copolymerization to prepare activated fly ash colloid,and through chelating agent,H⁺slow release agent to the activated fly ash colloid gel time control.When the concentration of sodium hydroxide is 0.5mol/L,the dissolution rate of the activated substance of fly ash is 15.29%,which can form a stable colloidal state with sodium carboxymethylcellulose,so 0.5mol/L sodium hydroxide solution is used for powder Coal ash is activated actively.Finally,the gelation characteristics,inhibition characteristics and fire extinguishing characteristics of activated fly ash colloidal materials under different proportions were investigated.The gelation characteristics of activated fly ash colloid include gelation time,viscosity,permeability and water retention.The minimum gelation time of activated fly ash colloidal system under different mixing conditions is 22min.The viscosity of the fly ash colloid has the greatest influence,so the activated fly ash colloid of 3%CMC tends to stay in the coal body and its permeability is only 30.37%.It was found through the water retention experiment that when the temperature reached 180?,the weight loss rates of 2%,2.5%and 3%CMC gel systems were 51.34%,45.75%and 38.87%,respectively.Among them,the weight loss rate of 3%CMC gel system is the smallest,indicating that the gelation characteristics of the 3%CMC activated fly ash system are good,so the 3%CMC activated fly ash colloid is selected to study the fire extinguishing characteristics.Inhibition characteristics studies include the effect of activated fly ash colloids on coal spontaneous combustion iconic gas,cross-point temperature,mass and heat changes at low temperature.It is found that lignite and coking coal after 3%CMC activated fly ash gel treatment The highest inhibition rate,its inhibition effect is better than CaCl₂ and 2.5%CMC activated fly ash gel.The burning stage of lignite lags about 20°C,and the peak exotherm lags about 40°C.It shows that the activated fly ash colloidal material can inhibit the coal spontaneous combustion process.Research on fire extinguishing characteristics After water and activated fly ash colloids were injected into spontaneous combustion coal bodies,it was found that when the water was injected into the spontaneous combustion coal bodies,the coal bodies re-ignited,but when the activated fly ash colloids were injected into the coal bodies,there was no re-ignition phenomenon And,the colloid can effectively stay in the furnace body,cover the coal body,and reduce the contact between the coal body and oxygen.Finally,through the micro-resistance experiment combined with the fire extinguishing characteristics of the activated fly ash colloid,the fire extinguishing mechanism of the activated fly ash colloid is studied.The addition of colloid will reduce the specific surface area of the coal sample,inhibit the contact ability between coal and oxygen,and at the same time The reaction rate of aliphatic C-H components in coal and oxygen-containing functional groups such as C=O makes the coal body difficult to spontaneously ignite.