Experimental Study On Fire Prevention And Extinguishment Of Film Mulching Gasifier Slag Composite Gel

Coal is our country's main fossil energy source.In the 2020 government work report,the country listed"Ensuring Energy Security"as one of its development goals.Thus,research on coal-mine fire prevention and control technology has listed as an encouraged industry.More than 60%of coal-mines fires are caused by spontaneous combustion of coal in the goaf.Among the common methods for preventing and controlling spontaneous combustion of coal,gel has the most advantages.However,the existing gels for preventing coal spontaneous combustion generally have the problems of low strength,short water retention time,and failure after water loss.To this end,this paper designs an environmentally friendly film mulching gasifier slag composite gel,which is strong,has a elastic solid film,and can still prevent spontaneous combustion of coal after loss of water.The preparation principle of the composite gel is:using sodium alginate(SA),sodium polyacrylate(ASAP),and gasification slag(GS)to prepare a viscous mixed slurry,and then using calcium chloride(CaCl₂)to induce gelation of the surface of the mixed slurry to form an elastic solid film.Screen out the best formula when using water with different pH through water retention experiment.When the composite gel is prepared with tap water,the water retention of the composite gel is the best under the mass ratio of the mixture slurry of CaCl₂ solution and gasification furnace slag is 1:2.At the same time,it is proved feasible to atomized spray calcium chloride solution to prepare composite gels through experiment.The temperature-programmed experiment results show that the compound gel's ability to inhibit spontaneous combustion of coal in descending order is the compound gel prepared according to the best formula of water pH=6,water pH=7.5,and water pH=9.The TG-DSC experiment results show that the thermal stability in descending order is the composite gel prepared according to the best formula of water pH=9,water pH=7.5,and water pH=6.In the range of30?-300?,the composite gel will not release heat as a whole to promote the spontaneous combustion of coal.On the contrary,the composite gel will decompose and absorb heat when heated.The test results of the plugging experiment show that the pressure difference of the composite gel prepared under the best formula of the water pH=9 is the best,the pressure difference of the composite gel prepared according to the best formula of water pH=6 is the worst.Fire extinguishing experiment results show that the composite gel prepared with different formulations can quickly cool coal to below 100°C within 200 seconds.and then extinguished due to oxygen isolation.Compared with gel foam,polymer gel,water glass/mud composite gel for prevent and control coal-mine fire,the developed film mulching gasifier slag composite gel has excellent performance and obvious advantages.Based on comprehensive analysis,it is recommended that the film mulching gasifier slag composite gel used to cover the leftover coal in the mined-out area should be prepared with the best formulation with the water pH of 6.It is recommended that the composite gel used to seal the air leakage channel and extinguish fire should be prepared with the best formulation with the water pH of 9.