Research On3-D Modeling Low Dilution For Ore Drawing

Pillarless sublevel caving method has many outstanding advantages, such assafety, low cost and high efficiency. It is widely used in the non-ferrous mines. Sofar more than80%of the ore body has been mined by using pillarless sublevelcaving method. The ore body is mined for pillarless sublevel caving method, underthe condition of overburden rock. This leads to large rock-ore contact surface,heavily mixed ore and rock, and many other problems, like great ore loss and highdilution of ore, which seriously affect production profits. Shachang mining areachanged from open pit mining to sublevel caving in2011. Parts of the ore areaadopted pillarless sublevel caving method and the cut-off grade ore drawing, whereis now suffering from many prominent problems, such as low ore recovery ratio andhigh ore dilution ratio.Although there have been some achievements after a lot of productive researchand practice on the mechanism of ore dilution ratio of pillarless sublevel cavingmethod done by many scholars and miners, the problem of high ore dilution ratiohas not been solved yet. It is necessary to conduct further research on the ore-rockflow law in the process of mining for pillarless sublevel caving method, but theexperimental study like multiple sublevel physical model and3-D numericalsimulation are not yet fully satisfactory with the practice. Based on ShouyunShachang mining area, Beijing, this thesis is focused on3-D numerical modeling ofpillarless sublevel caving method by using cut-off grade ore drawing and no (low)dilution ore drawing, which provides theoretical and experimental verificationsolution to ore dilution ratio’s problem.The following work were completed: A single draw-hole ore drawing model inPFC3D was designed to determine the numerical model’s parameters, whichverified that PFC3D could be used to simulate single ore-body ore drawing; Asingle sublevel and three ore drawing steps model was conducted both in laboratoryand PFC3D, which verified that PFC3D could be used to simulate multipleore-bodies ore drawing; A PFC3D model with multiple sub-levels and ore drawingsteps was established to study the ore-rock contact line of the two kinds of drawingmethods by employing the cut-off ore drawing method and the no (low) dilution drawing method, respectively.The conclusions are as follows: PFC3D can be well applied in ore drawingsimulation for pillarless sublevel caving; The cut-off grade ore drawing method hasa stable ore recovery rate from the fourth sublevel to the last sublevel; The no (low)dilution ore drawing method’s ore recovery rate is very close to that of the cut-offgrade ore drawing method with a quit low ore dilution rate after the fourth sublevel;Ore and rock are seriously mixed in a certain zone of the ore drawing steps ofcut-off grade ore drawing method; The adherent residue body has a very goodadjustment effect on ore recovery between steps; No (low) ore dilution methodcould be applied to Shachang mining area, which will bring huge benefits.