The article deals with the problems of mineral processing in separators with dense medium. Low and medium grade coals are not sufficiently concentrated in serial separator designs. The paper proposes an innovative design of a dense media separator with a membrane installed in its bath. The membrane is driven by an eccentric drive. Prevention of mixing of light fractions with heavy fractions is achieved due to the uniform distribution of material throughout the volume of the bath under the action of horizontal pulsating flows created by the movement of the diaphragm. As a result, more efficient concentration of material is observed compared to concentration in existing separator designs.