This paper represents a plant optimization (capacity improvement) study for a gold heap leach plant to obtain the product size of 100% of -6 mm crushed ore at a capacity of 180 Mg/h. The former plant flowsheet was re-designed to obtain the target product size and capacity by modeling and simulation. The plant measurements and ore test work were carried out as the first part of the design study. During the simulation phase, the model predictions (estimations) were calibrated based on the measurements and ore test work while developing the flowsheet. A flexible layout design and site construction were done after the flowsheet re-design by using available plant footprint as much as possible and providing production infrastructure by adding intermediate stocks. Finally, after 8 months of intensive work, the plant achieved 100% of -6 mm crushing product with the target size of 80% of -4.55 mm at a capacity of 200 (±10%) Mg/h.