A Mathematical Model for Short Term Production Scheduling in Open Pit Mines Based on Integer Programming

Short term production scheduling determines the sequence of ore and waste blocks extraction on shifty, daily, weekly or monthly bases. The objective of this production scheduling was to determine the block extraction period according to the production constraints including; grade blending, mine and mill capacity, and slope constraints. Several mathematical models have been proposed for short term production scheduling, but the equipment access constraints have not been incorporated effectively in that models. In this paper the mathematical model of short term production scheduling was developed in order to insure that a block can only be removed if all nine overlaying blocks and two or three surrounding blocks have been removed, in the previous or current periods. This goal was achieved by defining equipment access constraints. Mathematical inequalities were presented for equipment access constraints based on integer programming, according to the type of block access modes. These models were then applied to a case study, using Excel 2007 and solved via Premium Solver Version 9.0 software.