The Dispatching and Scheduling Problem of Heterogeneous Electric Mine Trucks by Considering Serve Queues

The progress of mining industry has brought about serious environmental issues while promoting the world economy. Applying electric mine trucks can not only decrease emissions but also save operational cost for operators of open-pit mines. This paper focuses on the mine truck dispatching problem in open-pit mines by considering electric mine trucks. Moreover, the queues at excavating, dumping, and charging locations are considered. Correspondingly, the detailed schedules of loading, unloading, and charging processes associated with trucks are optimized simultaneously to try to avoid queues and decrease waiting time. The rolling horizon framework is proposed to model the problem, and the dispatching and scheduling problem in each horizon is formulated by a mixed integer linear programming model. We propose a branch-and-price algorithm to solve the problem in each horizon. Since there are infinite constraints in the model, the surrogate relaxation technique is introduced in our algorithm to deal with the infinite constraints, and a tailored labeling algorithm is proposed to solve the corresponding pricing subproblem. The efficiency of proposed algorithm is demonstrated on the instances originated from an open-pit coal mine in China. Then, the benefits of introducing electric mine trucks and the impacts of truck fleet, battery capacity, and number of charging piles on production are discussed to provide managerial insights