The behavior of polydisperse second-phase inclusions in molten selenium during settling is modeled using solid carbon particles as an example. A theoretical limit of the particle concentration in the surface layer of the melt is evaluated as a function of particle size, and the particle concentration is determined as a function of time, melt viscosity, and surface layer thickness. The calculated histograms of the particle size distribution in the surface and bottom layers of molten selenium are in satisfactory agreement with experimental data.