Study On Ore Drawing Law And Structure Parameter Optimization In Natural Caving Method

The block caving mining method is widely used in the exploitation of thick ore bodies.The production process is greatly simplified by using the method, which can also be carried out with simple stope structure, easy management, high efficiency and low cost.However, there are also obvious disadvantages,mainly including bottom structure parameters optimization and drawing management system establishment. Therefore, it is necessary to further study the selection of reasonable parameters and the drawing law of caved ores during the process of ore flow, seeking to release ores in maximum extent and reduce the infiltration of surrounding rock so as to improve the indicators of loss and dilution. In order to obtain preferable technical and economic indicators of block caving method, based on the experience and achievements of predecessors, the Fuzzy Analytic Hierarchy Process (AHP) method and the fuzzy mathematics theory were used to optimize stope structure parameters. The basic principle of drawing was discussed by laboratory simulation tests,and ore drawing was simulated using the particle flow code software PFC 2D, thus to study ore drawing law and the mechanical motion state of drawing performance.First,according to large amount of fuzzy information in practical engineering, the comprehensive evaluation index system of decision optimization was established according to the AHP method, and the fuzzy mathematics method fundamental theory was used for structure parameter optimization.Comprehensive factors were considered in the method, including qualitative and quantitative indices.The weight of every factor was given for the AHP method, and the importance of every factor was evaluated to avoid the limitation of single criterion in the structure parameter.Then, the simulation experiment on bulk body was carried out using indoor physical model (multi-leak ore-drawing model),by which the drawing law of bulk body was studied. The research was mainly focused on the drawing law of adjacent leak bulk body under different ore drawing conditions and means.So the mutual impact between adjacent leak holes was understood. Moreover, the motion state and mechanical characteristics of bulk body were studies using the PFC 2D.According to the experimental results combined with on-site situation, a drawing mode suitable for production of ore had to be found to establish a reasonable ore-drawing management system. According to the different progress rates of field construction and the constraint of mining conditions,the drawing management system should be combined with field practice. Therefore, a drawing mode which combined the theory of free drawing and uniform settling was proposed and then applied to the actual production. The application of the theory was proved to be practicable through the analysis and evaluation of actual situation, and can be of relatively good economic value under certain ore-body condition.Therefore, the parameters obtained by Fuzzy-AHP are reasonable. And the established ore-drawing management system is feasible, through laboratory ore drawing experiments and simulation calculation of particle flow code software PFC 2D.It can have certain socio-economic values when popularized to mines with corresponding conditions.