Application of extremal optimization approach to the integrated scheduling problem of continuous casting and hot rolling process

Making an integrated schedule on both continues casting (CC) and hot rolling (HR) process in steel-making lines is a difficult problem since the balance of material flow, the continuity of production, the hot charge rate as well as the coupling between successive stages should be taken into consideration together. Therefore, few approaches have been published to solve the multistage integrated scheduling problem and applied to the real systems in practice. In this study, a novel modified Extremal Optimization (EO) algorithm combining exact mathematical model on CC stage and a heuristic algorithm on HR stage is proposed to solve the scheduling problem with less computational effort, and has been successfully applied to a real plant. The industrial application results show that compared with manual scheduling, considerable improvement in hot charge rate is achieved, leading to large energy-saving for the steel maker.