Integration of continuous caster and hot strip mill planning for steel production

In this paper we present a model and a solution approach for integration of steel continuous casters and hot strip mills to provide more responsive steel production at lower unit cost. We describe the production environment and survey existing methods for planning continuous casters and hot strip mills. Since these processes lie at the solid/liquid interface we use ‘virtual’ slabs, corresponding to possible (but not yet cast) solid forms of liquid steel, as a means of communication between hot strip mill and continuous caster. We model the planning problem as a hybrid network. Our model is solved using a combination of mathematical programming and heuristic techniques and we show that the solutions provided are very nearly optimal. The approach which we describe has been implemented at several steel mills worldwide and has demonstrated significant saving.