The separation of materials according to their density is carried out in a fluid bath by floating ground light materials and carrying same over an overflow, as well as depositing ground heavier materials on a horizontal sieve base within the fluid bath. In order to improve the floating of the lighter materials, a displacement body is cyclically sunk into the fluid bath. The fluid bath is supplied with additional fluid in a synchronous manner with the cyclical movement of the displacement body. A control device for supplying the fluid can also be connected to pressure sensors or the drive of the displacement body.

The separation of materials according to their density is carried out in a fluid bath by floating ground light materials and carrying same over an overflow, as well as depositing ground heavier materials on a horizontal sieve base within the fluid bath. In order to improve the floating of the lighter materials, a displacement body is cyclically sunk into the fluid bath. The fluid bath is supplied with additional fluid in a synchronous manner with the cyclical movement of the displacement body. A control device for supplying the fluid can also be connected to pressure sensors or the drive of the displacement body.