Optimal control of infiltration conditions in heap leaching

• Optimal control strategy developed for time-varying heap infiltration conditions. • Processing time reduced by over 40 % compared to constant infiltration profiles. • Outlet acid concentration constraint enforced for solvent extraction compatibility. • Smooth control trajectories enable implementation in industrial operations. In this study, we present a model-based optimal control strategy to determine time-varying infiltration conditions in heap leaching processes that minimize processing time while meeting recovery targets. Using a mathematical model of a copper heap leaching process with sulfuric acid as the solvent, we formulated and solved an optimal control problem without any data-driven model reduction technique, employing control parametrization with a single-shooting approach and a strategy of successive refinement. Compared to optimal constant infiltration strategies, the optimal control profiles reduced the process time by over 40 % while respecting outlet acid concentration constraints critical for the downstream solvent extraction step. The resulting inlet acid concentration trajectories are smooth and practical for real plant operation. These results demonstrate the potential of model-based optimal control to improve productivity and resource efficiency in industrial heap leaching processes, and the approach is adaptable to other hydrometallurgical leaching systems.