Sequencing Rules for Productivity Improvements in Underground Coal Mining

In this paper, we report on a unique two‐machine, dynamic sequencing problem that was involved in a project designed to improve the productivity of underground coal mining operations. It was discovered that mine output was dependent on the particular sequence of faces the continuous miner and bolter worked. The problem is characterized by two unique features. First, the problem is unique because of the geological and safety constraints that must be satisfied by the sequence. Second, the scheduling problem is dynamic because the available job sets change as work progresses, and the production times change as coal is mined. Three heuristic approaches were developed and tested using mine parameters. The best heuristic had a worst case scenario of being within 2.7 percent of the optimal sequence and only a 1.1 percent chance of determining a better sequence. This heuristic resulted in an 8.1 percent productivity improvement.