Analysis Of The Shear Stability Of Emulsion Explosive Matrix And Its Application

Emulsion explosive matrix(EEM)is a thermodynamic unstable system,which leads to the destruction of EEM in the process of high strength shear emulsification,transportation and storage,resulting in the separation of oil and water phase,the crystallization of ammonium nitrate,and ultimately leading to the decline of explosive performance and even explosion rejection.Shearing emulsification of EEM is an important link to ensure the quality and stability of EEM.Reasonable formulation and emulsification process can make EEM form uniform and fine droplets and have excellent rheological properties,which is crucial to improve the stability of EEM and the explosion performance after sensitization.Therefore,it is of great significance to study the shear stability and rheological properties of EEM for the safe production,stable storage and efficient utilization of EEM.This paper focuses on the shear instability process of EEM,the stability mechanism of emulsion and the dynamic behavior of shear emulsification process were analyzed theoretically.The influence mechanism of shear strength on rheological properties of EEM was studied.The constitutive relationship between the refining characteristic time of EEM and droplet size was proposed.A relationship model was established to characterize the shear stability of EEM.The interface properties and rheological properties of the composite oil phase were optimized.The shear agitation parameters of EEM were optimized by numerical simulation,and the results were applied to engineering practice.The main research work of this paper is as follows:(1)From the perspective of emulsion theory,the thermodynamic stability of EEM,the anti-coalestizing stability between dispersed phase droplets and the behavior of EEM in the process of shear emulsification were analyzed,and the factors and reasons affecting the emulsification effect and stability of EEM were discussed.The results show that the stability of EEM is closely related to the gibbs surface free energy between droplets,and it is mainly affected by the droplets supersaturation and interfacial properties.The interaction force between the droplets is mainly composed of Van Der Waals attraction,electrostatic repulsion and spatial resistance,etc.If the repulsion force is large enough,the droplets produce flocculation.If the interface membrane ruptures,the droplets coalesce.The shear behavior of emulsion is mainly influenced by its rheological properties and stirring shear parameters.(2)The rheological properties of EEM under different shear strengths were analyzed,and the influences of shear strength on the fluidity,thixotropy,viscoelasticity and viscotemperature characteristics of EEM were studied.The results show that the EEM is a pseudoplastic fluid with shear thinning,and its viscosity curve conforms to Herschel-Bulkley fluid relation equation.There is thixotropic phenomenon in EEM.With the increase of shear rate,the thixotropic modulus and thixotropic viscosity show a downward trend,and the thixotropic time is extended greatly.With the increase of shear rate,EEM needs higher strain to change from elastic deformation to viscous deformation,and its stability is relatively higher.The viscosity-temperature relationship of EEM conforms to the Arrhenius equation.The lower the temperature,the greater the viscosity of EEM and the more sensitive it is to temperature changes.(3)The properties of composite oil phase were analyzed by means of surface tension meter,viscometer and other instruments,and the influence of the properties of composite oil phase surface tension and dynamic viscosity on the stability of EEM was studied through high and low temperature cycling test.Based on the rheological properties test,a method was proposed to quantitatively characterize the stability of EEM by the change of storage modulus and yield stress,and the internal relationship between the microstructure and macroscopic properties of EEM was established by the analysis of the microscopic results.(4)Through the study of the theoretical analysis of shear fracture process of EEM and indoor test,put forward the characteristic time of EEM refinement and droplet size of constitutive relation,the characterization of EEM is constructed the Bn coefficient and dimensionless coefficient of shear stability of relational model,and studied the influence law of cutting parameters on the stability of EEM.The results show that with the increase of shear strength and shear time,the larger the diameter of the agitator,the more layers of the agitator,and the greater the contact area between the blade and the EEM,the more times of high and low temperature resistance of the prepared EEM,the better the stability and the higher the critical value.(5)Fluent software was used to simulate the shear agitation process of EEM,and the effects of blade parameters(blade type,diameter,layer number,etc.)on the velocity flow field,shear rate,turbulent energy intensity and mixing homogeneity of EEM were analyzed.The shear agitation parameters of EEM were optimized by numerical simulation.(6)The EEM with different formulations and different shear parameters was tested in the field by means of high and low temperature circulation,transport vibration,explosion performance test and other methods.The formulation technology and emulsification parameters of EEM in the open pit coal mine of Xinjiang were optimized to improve the stability and explosion performance of the EEM.