Simulation is widely used in design and optimization of mineral processing circuits to answer "what if" questions regarding the employment of different equipment and configurations. The questions could be answered better if the long-term economic impacts of different circuits are readily estimated within the designing stage, considering both economic and technical constraints and criteria. This paper introduces a new open source user-friendly techno-economic simulator developed in Matlab/Simulink that joins multivariate capital and operating cost models to technical models of equipment and estimates some economic analytical indicators of the circuits such as Net Present Value simultaneously when the circuit is being designed. The proposed approach enables the designer to easily consider the technical and economic interactions and tradeoffs. As a case study, the long-term economic impact of selecting different numbers of leaching tanks is investigated and it is shown that even the optimum number of tanks could be a function of discount rate of the project. (C) 2015 Elsevier Ltd. All rights reserved.