A model is presented to evaluate mineral processing on basis of gangue recovery and valuables recovery. It combines mineralogical limiting curves with upgrading curves in the Fuerstenau diagram. These curves are used to assess mineral liberation and mineral beneficiation compared with the ideal result. Two new parameters (ratio of separation and ratio of liberation) are calculated based on a comparison of areas enclosed by the mineralogical limiting curve, the upgrading curve, the curve representing a total liberation of valuables, and the curve representing a perfect mixture of valuables and gangue. An assessment of the success of mineral processing is possible using these parameters. The assessment shows whether the quality of a separation product is influenced by the separation process itself or by the achieved liberation of the feed. A series of experiments on the magnetic separation of a greisen-type ore proves the applicability of this model to mineral processing. SEM-based image analysis and ICP-OES measurements have been used to obtain the necessary data. (C) 2013 Elsevier Ltd. All rights reserved.