Application of Simulation and Optimization to Support Mine Plan Execution

Development of quarterly mine plans is time-consuming and requires consideration for many operational constraints and competing objectives. With lengthy turnaround times for updating quarterly plans, there is often limited opportunity to adjust quarterly plan details at the execution end of the planning process. Consequently, weekly and short timeframe plans may not account for some of the differences between actual state of the mine operation at the time of execution and expected state at the time that the plan was developed. Actual mining task completion times can vary significantly from the expected task completion times, due to many factors. In the absence of revision to account for differences between the planned and actual state, resource allocations, and mining sequences, embodied in the quarterly mine plan may no longer be the best approach for achieving an efficient mining operation at the time of execution. Simulation and optimization tools can be used to support rapid refinements for mine plan execution to preserve the value in the strategic mine plan. When initialized with an operations data feed to establish the actual state of the mine operation, optimization models can be used to both automate production of weekly or daily plans and maintain or improve on the performance objectives of quarterly and longer term plans. This approach can remove much of the manual burden of revising details of quarterly or longer-term plans for execution, if the plan no longer represents the best approach to meeting production objectives. Following initialization with the actual state of the mining operation, simulation models can provide an estimation of the range of likely mine operations performance, considering all available operations data. The models can be used to accelerate the planning process by providing visibility of future performance and identifying likely operational issues. They can also be used to test the robustness of the plan with respect to performance variability and response to disturbances. Following identification of issues, simulation models can also be used for evaluating mitigation measures, through automated testing of alternative plans. Integration of mine data feeds with simulation and optimization tools enables automated optimal responses to variations between the quarterly mine plan and actuals to be tested prior to release and implementation of an execution plan. The use of simulation and optimization in weekly mine planning is discussed in this paper with reference to example mining applications.