Research And Application Of Key Technology In Large Mining Height Fully Mechanized Face With Hard Roof And Stiffness Seam

The exploitation characters of 402 panel of the Jin Hua Gong Mine could be summarized as three points including hard roof,stiffness seam and large mining height.The fully mechanized caving faces were covered by 9# goaf and geological conditions were particular as well as excavate circumstances were scurviness,besides that it was hard to excessive the fault.Many fully mechanized supports crushing accidents happened during exploitation processes.Piston shoes were wear severity and the reliabilities of shearers were poor.And even replaced cutting pick frequently,get through the fault was failed.In order to realize safety and high-efficient mining for 402 panel and even the whole Jin Hua Gong Mine this paper took 8210 fully mechanized caving face in 402 panel as an example,researched on key technologies of passing fault in the conditions of “Two Hard” and great mining height.The main studies were summarized as follows:The mechanical properties of the roof rock mass and coal mass in 8210 fully mechanized caving face are tested.According to the distribution characteristics of coal seam and overlying strata,use RFPA numerical simulation software to establish the two dimensional model of “two hard” large mining height stope,research the overburden movement law and influencing factors of supporting and the breaking process of roof.Use the FlAC3 D numerical simulation software to establish the 3D model of "two hard" large mining height stope,research the destroy range of overburden,the distribution rule of abutment pressure,and the regularity of mine pressure.Provide data support for the design of hydraulic support.The mining conditions in 8210 fully mechanized caving face are bad,especially the mining height is above 5.0m.So the "three machines" matching system puts forward higher requirements.In this paper,the effect of impact load on the stability of support is studied.Through the design of hydraulic control system,the column,the support structure,four bar linkage mechanism to improve the impact resistance of the hydraulic support.The stress size of the parts of hydraulic support and the optimal operation parameters of the hydraulic support are discussed by the means of simulation analysis.For shearer,use the bottomless bracket,frame type combination structure.The main bearing part change into a driving-box.Adopte the method of flat butt joint,the high strength bolt is used for connecting the rocker arm.Because the shearer can’t through fault smoothly,author proposed a detachable pick-like bit.The pick head is made of hard alloy material(YG11C)with good wear resistance and high strength,and connected to pick body by the mutual occlusion of the rectangular tooth.Pick body is made of common alloy steel materials(42CrMo).Establish a three-dimensional model of new type pick-like bit,calculate the optimal length of the pick head and the gap parameter between the pick body and head.Establish the working mechanics model of pick-like bit,research its mechanical behavior.Research the tribological behavior of new pick-like bit,then compare it with the common picks.The results show that the new detachable pick-like bit can keep the design shape for a long time and has a long service life.Sliding shoe is one of the most important structural components in the shearer,which have the function of bearing and guiding.The special and harsh mining conditions of Jinhua Gong Mine lead to serious abrasion of sliding shoes.In this paper,Fe-Cr-B alloy as a new material is proposed.The tribological behavior between Fe-Cr-B alloy and pin made of 45# steel was studied by simulating the sliding shoe’s working conditions,such as choosing different sliding speeds and normal loads under the dry friction condition.Compare the results with the experimental results of 40 Cr and 20CrNi3 A steel under the same experimental conditions.The results show that Fe-Cr-B alloy can maintain excellent tribological properties,and can significantly improve the service life of Sliding shoe.The alloy material of existing sliding shoe is 18Cr2Ni4 W.In order to make full use of the existing sliding shoes,reduce production costs,the surface treatment technology is used to improve the performance and structure of the material of existing sliding shoes.In this paper,18Cr2Ni4 W was used as the substrate,and the alloying elements Cu and Ce were infiltrated on the surface of the substrate by double glow plasma alloying.Research the tribological properties and wear mechanism of the specimen through ring-block friction and wear testing machine.Provide technical support for prolonging the service life and improving the efficiency of coal mining.Taking 8210 fully mechanized caving face as a typical example,the industrial experiment is carried out.The fully mechanized caving face adopts the method of long wall retreating and comprehensive mechanized coal mining.The average mining height of fully mechanized caving faces is above 5.0m.Verify the performance and environmental adaptability of the new hydraulic support and shearer.The results show that the hydraulic support can satisfy the requirements of fully mechanized mining technology and fully mechanized caving faces support for the hard thick coal seam with 5.0m mining height.The shearer can run smoothly no matter cutting coal or coal gangue,and the vibration is not very large.And the wear and damage of the Sliding shoe is also less.