Experimental Study On The Preparation Of Coal-based Solid Wastes Materials To Inhibit Spontaneous Combustion In Gangue Hill

This paper relies on the project of "special fund of central leading local science and technology development: air pollution investigation and fire extinguishing technology research and demonstration project of coal gangue mountain spontaneous combustion in Wuhai mining area",in order to solve the problem of coal gangue spontaneous combustion in Wuhai mining area,measures are taken according to local conditions,and materials to suppress the spontaneous combustion of coal gangue mountain are prepared by using coal-based solid waste around Wuhai mining area.In this paper,fly ash,desulphurization gypsum,calcium carbide mud,cement and water are used as raw materials to study the new composite cementing materials.The raw materials are mainly industrial solid wastes such as fly ash,desulphurized gypsum and calcium carbide mud,which greatly reduce the cost and achieve the comprehensive utilization of solid waste.Based on the analysis of physical and chemical properties of raw materials,the ratio test of composite cementitious materials was carried out with the method of single variable.In the test,XRD techniques were used to analyze the crystal phase of materials,and SEM techniques were used to analyze the microscopic morphology of the hydration products of the composite cementing materials,and the hydration process and hydration mechanism of the composite cementing materials were further studied.The application of cementitious materials in a demonstration project of spontaneous combustion treatment of a gangue hill in wuhai was introduced.The main work and conclusions are as follows:(1)Through Single variable test exploring the influence of the proportion of fly ash desulfurized gypsum in the foundation group,the proportion of calcium carbide mud and cement in the additional group,the water cement ratio and the maintenance mode on the fluidity and water evolution rate of the composite cementitious spray material slurry,as well as the compressive strength of the solidified body and the chemical combined water.(2)The optimal ratio of composite cementitious materials is that the mass ratio of the basic group fly ash and desulfurized gypsum is 70:30,the addition amount of calcium carbide mud is 20%,the addition amount of cement is 15%,The gray ratio of water is 0.65,and the best curing method is film curing or watering curing.Under the optimal ratio,the fluidity of the composite gel-spraying material is between 90-100 mm,the water release rate at 6h is less than 5%,and the compressive strength at 28 d is 17.69 MPa.(3)The hydration mechanism of the composite cementitious material is the process of mutual excitation process of fly ash-desulfurized gypsum-calcium carbide mud-cement quaternary system.The volcanic ash activity of fly ash is in the alkaline environment provided by cement clinker and calcium carbide mud.Under the continuous excitation,under the action of desulfurized gypsum,the reaction generates hydrated calcium silicate gel,hydrated calcium aluminate gel,and ettringite crystals to provide strength for the system.(4)Utilizing composite cement material to develop blasting material for suppressing spontaneous combustion of gangue mountain,it has good sealing effect and achieves the purpose of suppressing spontaneous combustion.The grouting method has simple construction process and short construction period,and is successfully applied to solid engineering.