Modelling and optimizing storage assignment in a steel slab yard

Steel slabs are intermediates in the production of sheets, plates or coils in the steel industry. In this paper we consider cold charge slabs which are stored in stacks on a slab yard for a couple of hours, days or weeks until they are assigned to a rolling schedule and retrieved. When a slab is not positioned on top of a stack, retrieval requires the movement, also called shuffling, of all slabs above. We introduce a new model formulation, suitable neighbourhood and perturbation operators and discuss strategies for optimizing slab yard assignments with respect to shuffles and travel distance in picking.