NUMERICAL SIMULATION OF SURFACE MINE PRODUCTION SYSTEM USING PIT SHELL SIMULATOR

Surface mine production systems involve complex, multi-faceted and costly sequence of processes that must be planned, designed and evaluated to promote well-conditioned decision processes. Strategic and tactical mine plans are used to provide a long-term production vision and the resource requirements for meeting specific periodic mine and plant capacities. The schedule and sequence of material movement must respond quickly to changing technical, safety and economic constraints within the surface mining environment. Many production planning, scheduling and resource allocation methods are based on simplistic methodologies without rigorous technical and economic basis. These methods fail to consider the random processes governing critical production variables. With increasing demand for efficient schedules for low-cost bulk production requirements, the need for efficient tools is critical. In this study, the authors develop an innovative pit shell simulator to address these problems. Rigorous geometric formulations of the ellipsoidal approximations of the pit shells geometry, their planar expansions and vertical interactions are modeled to mimic material displacement dynamics in an open pit operation. Numerical simulation techniques are used to provide solutions to the time-dependent geometric models in random multivariate states. The pit shell simulator is used to solve the Pine Valley open pit mine production schedule for the first three years of production. The simulator provides the schedule and sequence of all the cuts from various quadrants in the four pit shells within the optimised pit layout. The simulator results show that, in order to maximize the mine value, the mine must produce 304,000, 180,000 and 140,000 tonnes of ore respectively for years 1, 2 and 3. The total materials within this period also include 72,000, 80,000 and 190,000 tonnes of stockpiles and 30,000, 80,000 and 30,000 tonnes of waste materials respectively for years 1, 2 and 3. This results in a maximum NPV of $27,000 at a discount rate of 12 percent over the 3-year duration.