Influence of moisture content on the shape of isolated movement zone in mesoscale

Block caving mining has the advantages of large production capacity, safe operation, low mining cost, and easy organization and management. Therefore, it is considered as one of the natural alternatives to the current open cut mining. The migration law of ore-rock and the design of ore drawing parameters during ore drawing are the key to block caving mining. The caving rocks usually contain pore water between the fine particles, therefore, the caving rock in an unsaturated state is a solid-liquid-gas three-phase coupling field. The electric double layer force as well as the ionic hydration force, electrostatic force, and Van der Waals force result in the interaction between adjacent particles on a molecular scale. However, the interaction is also resulted in the force of the liquid bridge. To explore the influence of moisture content on the shape of an isolated movement zone in block caving method under ore drawing in mesoscale, the stress between unsaturated ore particles was analyzed. The fine particles flow and discrete bulks of ore-rocks were investigated using lattice Boltzmann method (LBM) and discrete element method (DEM), respectively. Based on the LBM-DEM coupling algorithm, the ore-drawing models of the block caving method were constructed, and the relationship between the moisture content and the shape of the isolated movement zone was obtained. The accuracy and reliability of the ore-drawing models based on the LBM——DEM coupling algorithm were verified by comparing the simulation results with the existing research results. The results indicate that the moisture content of ore-rock has significant effects on the shape of the isolated movement zone. When the same ore-rock mass fraction is discharged, with an increase of moisture content, the height of isolated movement zone increases and then decreases, and the shape of isolated movement zone becomes slender and then is restored gradually. The critical value of moisture content during the change of isolated movement zone shape is about 10%.