Research On Key Technology Of Squirrelcage Selectivity Separation Equipment For Coal And Gangue Underground

Gangue, the accompanying mineral of coal mining, is always transported to theground and accumulated as hillock, and the human health and the mining environment areall influenced by it. Achieving separation for coal and gangue underground and backfillinggangue in situ is the method that can radically solve the environmental problems producedby discharge and accumulation of gangue. According to the differences in physical andmechanical properties of coal and gangue and combined with the structural characteristicsof the existing separation equipment for coal and gangue underground, put forward a newseparation equipment for coal and gangue underground—the Squirrelcage SelectivitySeparation Equipment for coal and gangue Underground.It has great significance on theselectivity separation for coal and gangue and the realizability of the coal green mining.Therefore, the theoretical analysis, numerical simulation and experiments are combined toinvestigate the key technology of the Squirrelcage Selectivity Separation Equipment forcoal and gangue Underground.According to the structure character and the crushing process of the SquirrelcageSelectivity Separation Equipment for coal and gangue, the mechanics models of the impactbetween the particles for coal and gangue, the particles and the crashing rod, the particlesand the drum wall were built, which based on the the Hertz Theory and the TimoshenkoTheory. And the theoretical formula of the impact velocity of the coal and gangue wasdeduced, which provides the theoretical guidance for the selectivity of the structureparameters and motion parameters of the equipment.The simulation of the impact crushing of single coal particle was done by discreteelement method, and the simulation model was proved by experiment. The influence of theimpact velocity to the crushing model of single coal particle was analyzed, which utilizesthe finite element and the discrete element methods. And the influence of the characteristicparameters of the coal and section style of the impact rod to the coal crushing was acquiredby researching on the single coal particle crushing. The results indicate that: therelationships among the impact velocity and the compressive strength, the elasticity, thecoal density are all power exponent. And the simulation results and the theoretical resultshave good uniformity, which proves the theoretical formula of impact velocity is correct.The influence of the section style and parameters of the crashing rods to the impactvelocity and the impact load of the coal is remarkable. The impact velocity of the coaldecreases with the increases of the section angle of the crashing rod, the impact load increases along with the section angle when the section of crashing rod is triangle; theimpact velocity decreases along with the radial of crashing rod increases, while the impactload increases along with the rod radial increases when the rod section is cylindrical.The influence rules of the drum numbers, the characteristics of coal, the drumstructure parameters, the drum mechanical parameters and the blanking height to thecrashing effect of the coal and gangue were researched based on the experiments. Theresults indicate that: the separating equipment with three drums is better to satisfy therequirement of the selective crashing separation of the coal and gangue. The best crashingrotary speed of different compressive strength for coal and gangue is different; In thestructure parameters of the drum, the influence of the radial of the crashing rod to thecrashing effect is small, the numbers of the crashing rod is remarkable; and the relationshipbetween the crashing ratio and the drum rotary speed is linearly, which influenced by theblanking height is small.Dynamic characteristic of the particle group in the separation equipment wasresearched by utilizing the discrete element method. The contact model of the coal particleand crashing rod was built, and the significance tests were done on the influenced factorsof the coal crushing rate by orthogonal experiment. The tests indicate that: the influence ofthe drum rotary speed, the rod space, the coal feed position on the crushing rate isremarkable. The discrete element method was used to research on the dynamiccharacteristic of the particle in the drum and the crushing rate of the coal and gangue werestudied under the condition of different drum, different rod space and different materialfeed position. The results indicate that: the crashing behavior happens between the drumand the shell of the equipment; the velocity amplitude caused by the impact between themiddle drum and the particles is small, while the velocity amplitude caused by up drumand down drum are bigger; and the crashing effect is best when the drum with six rods.The simulation was done on the reliability of the crashing rod, the natural frequencyand the dynamic stress of the crashing rod were analyzed for different rod diameter anddifferent rod length, which provides the design parameters for the improvement of thecrashing rod.