Study on Dynamics and Coal Breaking Characteristics of Gas-Solid Two-Phase Jet with High-Pressure Pulverized Coal
In order to further strengthen the ability of high-pressure jet to break coal rock and reduce energy consumption,a coal breaking method of gas-solid two-phase jet with high-pressure pulverized coal was proposed based on the theory of in-situ physical crushing fluidized mining.Based on the DPM discrete phase model,the flow field structure characteristics of gas-solid two-phase jet and the acceleration law of pulverized coal were clarified.The RHT constitutive model of coal rock was constructed.The coupling model was established by DEM-FEM method,and the propagation of stress wave and dynamic damage law in coal rock during erosion were explored.The energy consumption and coal breaking effect of gangue-water jet and pulverized coal particle jet were compared and analyzed.The results show that with the increase of the refractive flow pressure,the fluid state changes from over-expansion to under-expansion,and the Mach disk structure of the flow field becomes more obvious.Increasing the jet pressure can increase the impact energy of the pulverized coal particle jet,which is beneficial to strengthen the internal stress wave effect of the coal rock,prolong the effective action time of the stress wave,aggravate the damage of the coal rock,and the coal rock is more easily destroyed by the shear form.With the increase of propagation distance,the stress wave will have a certain degree of dispersion and amplitude attenuation,and the attenuation rate increases with the increase of jet pressure.At the same impact velocity,the macroscopic damage of coal rock by pulverized coal particle jet is more serious,and its erosion rate is 1.78 times that of gangue-water jet,and the corresponding specific energy consumption is only 56％of that of gangue-water jet,showing better coal breaking characteristics.The research results can provide some theoretical support for the application of coal breaking by gas-solid two-phase jet.
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