Track: Facilities Planning and Management

Abstract

The developed model and heuristic solution approach are used to eliminate material waste experienced in scheduling of continuous caster process, provide more responsive steel production at lower unit cost and effective capacity utilization. In steel making, the molten steel passes through a continuous caster to form large steel slabs, which are rolled into coils and rods at the finishing. Presently, at Ajaokuta steel complex, the issue seems to have defied solutions because the complex lacks effective and efficient scheduling tools to tackle it. The methodology of winner determination using a combinatorial auction based-heuristic approaches to solve the aforementioned problem is applied. The scheduling problem in continuous casting stage was formulated as a linear integer program to determine the scheduling sequence for different charges. Then bids are obtained for sequencing the charges. Next, a heuristic approach is used to evaluate the bids. Combinatorial auction based approach minimized the large search space and discontinuity encountered during optimal solution. The computational results show that the algorithm obtained optimal solution of 15 tonnes in 35 minutes of 15 charges per shift. Also, there is a 43% reduction in production cost per tonne. These are substantial improvements by and contributions of this study.

Keywords: charges, continuous caster, combinatorial auction, scheduling model, steel slab.