This paper deals with some methods used to separate and to evaluate emission of dust particles coming from various industrial origins. Locations of all sources are supposed to be known by their 3D-Cartesian coordinates and steady-state dispersion is assumed to be reached. Our main contribution is to combine a particular stationary dispersion model with some efficient separation methods. The estimation of particles flow for the case of point sources over flat terrain is first addressed and then it is extended to line or area sources. Anyway, the approach is divided into two specific steps: the stationary model presentation and the separation techniques applied to the previous model. Finally, simulation results show the performances of the different methods in case of point. It turns out that small variations on the wind angle lead to large errors on flows estimate. Robust techniques with respect to model uncertainties appear to be of prime interest.