A method and apparatus for separating solid particles of different densities, using a magnetic process fluid. The solid particles are thoroughly mixed in a small partial flow of the process fluid. The small turbulent partial flow is added to a large laminar partial flow of the process fluid, after which the obtained mixture of the respective partial process fluids is conducted over, under, or through the middle of two magnet configurations, wherein the particles are separated into lighter particles at the top of the laminar process fluid and heavier particles at the bottom of the laminar process fluid, each of which are subsequently removed with the aid of a splitter. After that furthermore the particles of low density and the particles of high density are separated from the respective process streams, dried and stored. Finally, the process fluid from which the particles have been removed is returned to the original starting process stream. The method according to the invention is especially suitable, for example, for separating a mixture of polypropylene particles and polyethylene particles.