Stacker-reclaimer scheduling for raw material yard operation

Raw material yards at dry bulk terminals act as temporary buffers for inbound and outbound raw materials. Both discharging and charging processes are supported by raw material yards in most cases. Stacker-reclaimers are dedicated equipments in yards for raw material handling. The efficiency of yard operation depends to a great extent on the productivity of stacker-reclaimers. Stacker-reclaimer scheduling problem is discussed in this paper. Given a set of handling operations in a yard, the objective is to find an optimal operation sequence on each stacker-reclaimer so as to minimize the makespan. A mixed integer programming model is formulated. Since the considered problem is NP-hard in nature, a parthenogenetic algorithm is developed to obtain near optimal solutions. Computational experiments are conducted to examine the presented model and the solution algorithm. The computational results show that the proposed parthenogenetic algorithm is effective.