Extraction and Backfill Scheduling in a Complex Underground Mine

We use mathematical optimization to determine a production schedule (i.e., a schedule of extraction and subsequent filling of the voids) for a complex underground mine in Ireland. The goal of the mining operation is to maximize metal production over the life of the mine, subject to constraints on maximum monthly extraction and backfilling quantities, maximum and minimum monthly metal production, and sequencing between extraction and backfilling operations. We solve our integer programming model with a heuristic to produce a schedule that adds value to the mining operation by (1) shifting metal production forward, (2) reducing waste mining and backfilling delays, (3) avoiding expensive mill-halting drops in ore production, and (4) enabling smoother workforce management.