<p>Effective management of waste dumps in open-pit mines represents a significant environmental challenge that necessitates strategies to prevent or mitigate the formation of Acid Rock Drainage (ARD). Existing methods often fail to evaluate the long-term geochemical stability of waste dumps or integrate predictive modeling into the design process. To address this gap, this study develops an optimization–simulation model that integrates Mixed-Integer Programming (MIP) for waste dump design with reactive transport simulation (RTS) under future climate conditions. The MIP model designs the dump to ensure that the Neutralization Potential Ratio (NPR) in each waste cell remains, to the greatest extent possible, above the critical threshold. The RTS model subsequently evaluates the stability of this design in terms of changes in rainfall intensity and dump permeability, as well as the potential for ARD generation over 10-, 50-, and 100-year time frames. Unlike previous static and short-term studies, our framework establishes a dynamic interaction between optimization and simulation, enabling feedback-driven, long-term stable designs. The model was applied to an iron ore mine in Australia, demonstrating that NPR increased over time (with minimum values of 15, 20, and 25 observed at years 10, 50, and 100, respectively), indicating a reduced long-term risk of ARD. These results highlight the practical advantage of the proposed approach in delivering geochemically resilient dump designs that are robust under future environmental conditions.</p>