Study On The Theory And Application Of End Drawing In Sublevel Caving Without Sill Pillar

Sublevel caving without sill pillar is widely used in mines at home and abroad because of its advantages of simple and safe technology and high mechanization.However,the typical feature of this mining method is ore extraction under overburden,which has serious ore loss and dilution problems.Therefore,in order to improve the recovery efficiency of ore resources,improving process parameters,optimizing stope structure and so on have been important research topics of this mining method.Based on the engineering background of Chengchao Iron Mine in the east of Hubei Province and the starting point of improving the ore recovery efficiency,three research contents are put forward,including the research on the flow rule of ore dispersion and the mechanism of dilution loss,the research on the theoretical profile form of the end ore drawing body and the research on the realization way of low dilution ore drawing.First of all,carry out the end single route drawing similarity test,test the distribution of the amount of hole reached in the drawing space through the method of marking particles,and draw the profile shape of the drawing body based on the amount of hole reached curve;Based on the analysis of the experimental form of the ore drawing body and the ore drawing theory based on bergmark Roos equation,the theoretical form formula of the ore drawing body under the end ore drawing condition is derived,and the results are compared with the random medium theory;Then through the numerical simulation software of particle flow,according to the principle of cut-off grade and low dilution ore drawing,the numerical simulation of ore drawing is carried out respectively to explore the mechanism of ore loss and dilution under different ore drawing methods;Finally,based on the above conclusions,a reliable low dilution mining plan is established by optimizing the ore drawing conditions and ore drawing management methods.The results show that the ore-drawing body at the end of the ore drawing condition has an ellipsoidal defect,which is wide at the top and narrow at the bottom;Compared with the random medium theory,the theoretical form of the profile derived from bergmark Roos equation is more concise and the physical meaning of parameters is more clear,which is conducive to practical application.Combined with the above research results,this paper summarizes the existing problems of low dilution drawing,puts forward the optimization method of stope structure parameters suitable for low dilution drawing,constructs the relationship between the total amount of drawing and the average grade of drawing ore,achieves the purpose of controlling the grade of drawing ore by controlling the amount of drawing ore,and forms a reliable low dilution mining scheme.