The characterization of the segregation phenomena in binary mixtures of solids with very different densities and/or particle sizes is highly relevant in many industrial processes. As a recent example, some advanced CO2 capture systems using fluidized beds include the separation by segregation of the functional materials. In this work, we have conducted mixing-segregation experiments with particles of iron ore (a typical oxygen carrier in chemical looping combustion systems) acting as jetsam, and glass beads (representing a lower density solid present in the bed) acting as flotsam, to measure solid concentration profiles at different fluidizing gas velocities and mixture compositions of different-sized particles. The experimental concentration profiles have been interpreted using a modified version of the model proposed by Gibilaro and Rowe. A relatively simple correlation is included in the model to calculate the segregation model parameters, which depend on the physical properties of the fluidized solids. The model fits reasonably well with all experimental data, especially for mixtures with a low fraction of oxygen carriers, which are the most relevant for the design of future continuous separation of solids by segregation.