An integrated production batch planning approach for steelmaking-continuous casting with cast batching plan as the core

The development of the high-efficiency continuous casting technology makes it possible to continuously cast with multi-cast batching plans. The preparation of such steelmaking-continuous casting (SCC) production batching plan has become a new requirement to promote the efficient steel production. From the perspective of overall production system, an integrated approach with the cast batching plan as the core was proposed, which changes the step-by-step optimization way of combination and sequencing for preparing charge batching plan and cast batching plan sequentially. This approach, which can perform integrated combination and sequencing, directly prepares the SCC production batching plan with multiple cast batching plans that can be continuously cast, and takes into account the charge batching plans. Taking minimizing the weight of unplanned slabs, maximizing the production efficiency of continuous casters, and minimizing the penalty value for the change of dimensions of the adjacent slabs as the objectives, a multi-objective mixed-integer programming model was established. An improved NSGA-II combined with a local search strategy was designed, and the practical aspects such as multiple grades continuous casting rules and on-line width adjustable rules were considered. The test result with data from a steel plant in China indicated that the improved algorithm could obtain better slab combination sequence results compared with the NSGA-II and SPEA2. Simultaneously, compared with the manual approach and the traditional approach of preparing the charge batching plan and cast batching plan sequentially, the integrated approach can not only reduce the residual material rate by 4.96% and 0.42%, improve the quality of the solution, but also improve the efficiency of planning.