This paper attempts to incorporate equipment selection/allocation into the optimization of open pit mine production scheduling. Equipment selection has been conventionally treated as a separate procedure in mine planning, and this separation may lead to undervaluing a mining venture or may generate schedules that may not be compatible deposit characteristics. The motivation for this work is the fact that the equipment cannot be selected without knowing production rates and the sequencing of blocks to be mined; similarly mining blocks cannot be sequenced without selecting equipment. Thus, block sequencing, ore-waste discrimination and equipment selection would be optimal if optimized concurrently. The concurrent optimization of the above sub-problems is formulated herein as a mixed integer programming (MIP) optimization problem. Equipment operating costs, which have been included in mining costs in previous studies, are used as coefficients in the proposed MIP optimization formulation. The reliability of the optimal solution requires comprehensive cost engineering, which leads to the classification of equipment costs into three groups: depreciation, preventive maintenance and other operational costs. The objective is to maximize the net present value (NPV) of a project under the constraints of capacities, access, equipment relations and matching. Afterwards, mining block extraction times and destinations, as well as equipment types to be used are determined. A case study demonstrates the model developed for a gold mine. The findings show that the optimization model can be used in the mine planning procedures.
Published September 2013 , 17 pages