Mineral concentrators can be designed to support several modes of operation, which can be optimized for different geometallurgical units. Nonetheless, alternative modes often require additional equipment and processing capacity, hence an associated capital expenditure. Moreover, the concentrator designs are often based on preliminary geological data, and are therefore subject to uncertainty. The current paper describes how stochastic mine planning algorithms may be extended to quantify the net present value (NPV) of alternative operational modes in mineral processing plants, under geological uncertainty. In particular, the Variable Neighbourhood Descent method of Lamghari et al. (2014) was originally developed for open-pit mine planning, and has now been adapted to evaluate concentrator operational modes. Sample computations are presented. (C) 2017 Elsevier B.V. All rights reserved.