Bayer digestion maintenance optimisation with lazy constraints and Benders decomposition

Abstract This paper describes a maintenance scheduling model for digester banks. Digester banks are network-connected assets that lie on the critical path of Bayer process, chemical refinement process converts bauxite ore into alumina. The require different activities at due times. Furthermore, schedule is subject to production-related constraints and resource limitations. Given complexity large fleets banks, continuous-time, mixed-integer linear program formulated find cost-minimising satisfies all required constraints. A solution approach employs lazy Benders decomposition proposed solve model. Unlike generic implementations decomposition, we show subproblems can be solved explicitly using specialist algorithm. We realistic scenarios involving two refineries based in Western Australia.