Abstract:

According to proposed plan, Sin Quyen copper mine will extract more deeply by surface mining method to level -400m. This means the mine will go deeper about 200 m in comparison with the suggested final bottom at the Eastern area of the mine at level -188 m. An important problem that the mine need attention is to mine safely and effectively. The stability of benches and final pit slopes when mining deeper has an important meaning to the mine. Presplitting blasting is the solution that has been effectively applied for this purpose. This paper presents an approach for determining presplitting parameters that based on the numerical simulation by finite element method by Phase2, with the input data from properties and characteristics of rock at Sin Quyen copper mine. The presplitting borehole with the diameter of 127mm is put in to examine; the spacings between presplitting blastholes in rock layers above and below ore body are calculated with the values of 0.5m, 1.0m, 1.5m, 2.0 m, respectively. From the numerical simulation results to study the relation between pressure and spacings, it can be seen that the required blasting pressure inside the blasthole to create main crack between presplitting blastholes is from 210 MPa. From the the analyzing results, the required blasthole pressure in relation with spacing of presplitting blastholes and rock properties. This can be used for determining charge weight and structure of presplitting charges