Ladle Scheduling Models And Algorithms For Steelmaking-Continuous Casting Production Process

In steelmaking-continuous casting, ladle is the carrier of the entire production process from steelmaking process to continuous casting process.So ladle scheduling play important roles in balancing the load of working procedure, tightly linking up the material flow, shorting the waiting time between working procedures, highly improving production efficiency, quality of products and production flexibility, decreasing the consumption of energy sources.In this paper, the ladle scheduling problem can be modeled as the problem of vehicle routing problem with time windows and adjustment time (VRPTW-AT). We consider the objective of minimizing the total number of used ladles. According to the process programs of ladle servicing molten steel, a optimization model is proposed for ladle scheduling problem, and a scatter search (SS) algorithm and a stochastic local search (SLS) algorithm are presented to solve the model. C++language is used to realize the model and algorithm. We cite the practical instances from a Chinese iron and steel plant to test the model and algorithm. In experiments we compare practical results of the plant with the results obtained by the SS algorithm and the SLS algorithm. Computational results show that the mathematical model and the algorithm are effective for solving the ladle scheduling problem.