In this work, we apply the attainable region (AR) method to laboratory data in order to optimize the milling and leaching processes of a low grade gold ore. To date, no research has been published on the application of the AR optimization technique on combined milling and leaching processes. The advantage of the AR approach lies in its ability to simplify the optimization problem, as searching over a defined space for the maximum of an objective function is a fairly standard procedure. The objective function we selected in this investigation was that of optimizing a linear function of the value of the recovered material minus the cost of both milling and leaching. Using the three variables (milling time, leaching time and recovery), we constructed a 3D plot and used it to obtain all the possible recoveries from the different milling and leaching times. The optimum for our chosen objective was then found by overlaying a contour plot of the objective function on the 3D plot. Our results show that the optimum was obtained at 90% recovery with a profit value of $600, milling time of 30 min and a leaching time of 1750 min. (C) 2017 Published by Elsevier B.V.