Multiphase flow inside first-stage cyclones in the clinker burning system was analysed and described based on numerical and experimental research methods. The research was preceded by operation tests on two industrial installations. This allowed for the reproduction of real operation conditions and the construction of the research station. In total, 57 geometric configurations of cyclone separators were studied. Data collected from calculations of computational fluid dynamics (CFD) and laboratory tests were compared in order to determine the reliability of the obtained results. The presented methods of analysis of flow inside the apparatus helped prepare design guidelines for first-stage cyclones used in clinker burning. The proposed guidelines enable the design of high-performance cyclones for specific operating conditions of a given installation depending on the objective function adopted in the design optimisation process. Furthermore, the proposed structural changes may be applied in traditional cyclone dust separators as a solution to the continuously decreasing allowable limits of dust concentration in atmospheric emissions. (C) 2015 Elsevier B.V. All rights reserved.