The optimal design of flotation circuits is a complex task because the mathematical model is non convex and it includes binary variables, making it difficult to obtain the global optimum solution. Furthermore, the modeling of the recovery of each concentration stage is complex, requires experimentation, and depends on many variables, including the selected circuit and mineral feed (which is heterogeneous and changes over time). These difficulties indicate that there are uncertainties in the actual values of the recovery of each stage and the information required to create the circuit design. This paper demonstrates that, for a specific mineral, few structures exist that are optimal for a wide range of values of concentration stage recoveries. This knowledge can be useful in circuit design, e.g., after selecting the circuit (or the most promising circuits), the equipment design parameters and operating conditions can be defined based on simulation and laboratory tests. (C) 2015 Elsevier Ltd. All rights reserved.