| The pillarless sublevel caving method has the advantages of high mechanization,safety and efficiency,so it is widely used abroad,and is also an important mining method in the underground mining of metal mines in China.In the study of the mining effect of this method,there are more studies on the stope structure parameters,blasting parameters,side hole angle,drawing hole size,etc.,but less on the mining method.Therefore,on the basis of establishing the physical model of non-pillar sublevel caving method,this thesis has carried out the multi-section physical experiments of single-pass and double-pass stoping of non-pillar sublevel caving method,and studied the impact of single-pass stoping and double-pass stoping on the loss rate,dilution rate and non-poor ore extraction effect;At the same time,the mining method is further studied by numerical simulation,and the influence of mining method on ore drawing effect is explored from the aspects of bulk flow characteristics and ore dilution law.Based on the end ore drawing test,the ore drawing test research is carried out through single drift mining and double drift mining.Research findings:(1)In the process of multi-stage stoping and drawing experiment,compared with single-entry drawing and double-entry drawing,the quality of ore recovery of double-entry drawing is obviously higher than that of single-entry drawing in the stage of no lean drawing;Up to the stage of taste drawing,the ore loss rate of double stoping approach is smaller than that of single stoping approach,and the difference of ore returning to poverty is large,which can effectively improve the drawing effect.(2)Based on the rule of ellipsoid movement of ore and rock during ore drawing,when the loose coefficient is greater than 1,combined with the vertical decline of ellipsoid in the actual recovery process,it is found that the reason for the sequential dilution phenomenon in the recovery process is that the decline speed is affected by the retardation coefficient,so the early dilution phenomenon of single stope access is found.In the process of dual access ore drawing,the overall changes of ore dilution rate and pure ore recovery of single stope access ore drawing or dual stope access ore drawing are consistent.Compared with single access ore drawing,the particle movement rate of dual access ore drawing is relatively slow,the curve decline of the ore rock contact surface is relatively gentle,and the change of the ore rock contact surface is relatively small,thus delaying the rupture of the waste rock funnel and prolonging the lean free mining stage,The quality of ore mining in the non poor mining stage is increased.(3)Combined with the actual particle velocity equation in the ellipsoid like ore drawing theory,the internal density of the particle is different during the movement of the ellipsoid like ore drawing;Under the condition of the same recovery times in the non poor recovery stage,the internal density of the granular ellipsoid of the single stoping access road is smaller than that of the ellipsoid of the double stoping access road;Combined with the recovery of ore and waste rock in physical experiments and the overall volume of bulk in the box,further analysis verified the equation derivation results.(4)PFC3D numerical simulation is used to establish a single subsection mining model to study the ore drawing effect of single and double stopes.The results show that the recovery rate of double stopes is obviously fluctuating with reference to that of single stopes in the lean recovery stage.The average ore recovery quality is 5.18%higher than that of single stopes,and the recovery rate is 106.7% of that of single stopes.The overall ore drawing effect is better than that of single stopes. |
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