A mixed-integer linear programming formulation for the scheduling of reclaimers in ore stockyards to minimize total tardiness

Stockyards are essential components of the mining logistics chain. In general, reclaimers are used in these stockyards to reclaim the ore from the stockpiles, transferring it to conveyor belts to take it to other locations. The scheduling of stockpile reclaim operations in ore stockyards is a scheduling problem on unrelated parallel machines, with setup times dependent on the sequence, due date, and machine eligibility. This study proposes a mixed-integer linear programming formulation to minimize the total tardiness. The formulation was implemented in the Gurobi solver and tested on small instances generated from operational data from the Port of Tubarão. The results showed that the solver was able to find the optimal solution for instances with up to 10 jobs and four reclaimers.