Separation of ordinary sand and bentonite used in the preparation of drilling mud into fractions in a new type pneumatic multi-cascade cylindrical stepped classifier and cleaning of the dust-air mixture separated from the process was considered. The experiments were carried out for both dispersed particles at different values of the height of the steps, the amount of solid materials, the amount of air, the speed of the air flow, and the influence of the geometrical and technological parameters of the device on the separation process was studied. By adjusting these parameters, fractions of any size can be obtained. Depending on the size, density, shape, and chemical properties of the dispersed particles, it is possible to adjust the technological parameters of the process in the device. The dust-air mixture separated during the process is first sent to a dry dust collector, and then to a wet dust collector. Here, the air is cleaned of dust and fresh air is released into the atmosphere. In addition to the fractionation of dispersed particles, this environmentally friendly device can be used in catalytic processes, sorption processes, and filtering processes. The developed technological scheme also allows the placement of a shredder unit if necessary.