Study On Shape Of Drawn Out Body In Non-pillar Sublevel Caving Method

Non-pillar sublevel caving method is widely used in underground iron ore mines both at home and abroad with the features of its safety and efficiency and lower cost.During the mining process with this mining method, the three deferent bodies, which include the drawn out ore body, loosened body and caved ore mass, restrict each other and have a great effect on the dilution and loss index. As for this reason, it has important theoretical and practical value for improving ore recovery rate and economic benefit of mines to study on the shapes of drawn out bodies with different shape of caved ore masses.Based on the summary of the results of previous studies, in this paper, combined with the status of the application of non-pillar sublevel caving method in Yanqianshan Iron Mine, the shapes of drawn out bodies in response to different shapes of caved ore masses are studied through theoretical analysis, computer simulations and laboratory experiments and other methods. The research of this paper achieved conclusions as follows:1. It provides a guidance for the laboratory experiment via the numerical simulation on the ore drawing out in non-pillar sublevel caving method in Yanqianshan Iron Mine through the ore drawing out in laboratory, the amount of the drawn out ore and rock is analyzed with changes of the number of drawing out, the ore dilution rate and recovery rate were calculated, the shape of drawn out bodies were restored by means of marked particles and drawn out granular materials.Summarizing the formation theory of emission body, loose body and caved ore mass avalanche in the system, which laid the theoretical foundation of the emission body shape.2. The simulation experiment on ore drawing with different shape of caved ore bodies were conducted by ANSYS software, which intuitively reproduced the process of ore drawing and the moving process of the particles in different locations in the caved body, the law of particles moving in the process of drawing out was statistic analyzed.3. The testing results of ore drawing out in laboratory experiment show that with the increase of the numbers of drawing, the ore began to dilution out after reaching a certain number of times under the different shape of caved bodies. Farther more, ore dilution rate is continuously increasing, and ore and rock are hybrid obviously.4. Experiments show that the shape of drawn out body presented the feature of small in the upper part and big in the lower part at the beginning of drawing out. Withthe ore drawing, the shape of drawn out body gradually widened, but the widening speed of upper part was obviously higher than that of lower part, the widest position gradually moved to the upper from the lower, and subsequently the shape of drawn out body emerged that the upper is larger than that of lower.5. The conclusion that the shape of drawing out body in the second set of experiments was s close to the shape of caved body is obtained via variation chart of drawn out bodies in response to different shape of caved ore masses restored by the drawn out ore and the marked particles. Under the condition of non-dilution drawing, the ore recovery rate reached of 52.20%, when cut-off drawing, 0re recovery rate reached of 78.28%. This provides a basis for finding the best shape and optimizing the structure parameters caved ore mass.