Sequence optimization in longwall coal mining

BHP Billiton’s Illawarra Coal operates several longwall coal extraction systems in the Bulli and Wongawilli coal seams in the Southern Coalfields of the Sydney Basin, Australia. IC has applied a proprietary mixed integer linear programming open pit strategic mine planning tool called Blasor to rapidly evaluate, for a number of longwall mining domains, the jointly optimal underground development strategy and mining sequences necessary. For each development scenario, the Blasor optimizer maximizes the discounted operating cash flow as the objective function, subject to mining, processing, and transportation capacity constraints and product blend constraints. When applied to the underground longwall domain sequence optimization problem, Blasor evaluates a set of carefully considered scenarios, each describing a feasible underground development and transport strategy. In this application, Blasor plays the role of a fair valuation tool for each major scenario, by determining the most valuable extraction schedule for each development scenario. This establishes a basis for comparing the economic merits of competing scenarios that are structurally different.