A new branching scheme for the open pit mine production scheduling problem

The design and scheduling of open pit mining operations is an enormous complex task. Given a discretisation of an orebody as a block model, the open pit mine production scheduling problem (OPMPSP) can be defined as finding the best extraction time for each block over the lifetime of the deposit. Despite the importance of minimum resource constraints in practical applications, they significantly increase complexity for solving the scheduling problem. Several heuristics, which employ the concept of Branch and Bound (BB however, they are still not efficient enough due to the deficiencies in the traditional B&B and B&C. In this paper, we propose a new branching scheme based on the concept of using type-1 special ordered sets for the OPMPSP, while considering the aforementioned resource constraints. By fixing variables at nodes, this scheme can substantially accelerate the branching-based heuristics. For the purpose of evaluation, we add our scheme to B&B and B&C, solving several randomly generated instances, and compare the results to those given by B&B and B&C. The results demonstrate that the scheme can significantly improve the performance of B&B and B&C, thus improving the heuristics that use these techniques.