A sedimentation separator for separating solids fractions from a mixture consisting of air, liquid and solids fractions comprises a sedimenting vessel (44) to which an air-separating unit (16) is connected upstream. In an intermediate vessel (36) arranged between the air-separating unit (16) and sedimenting vessel (44) there is arranged a float (64) which closes off an air duct (20) when the level of sediment in the sedimenting vessel (44) has reached a predetermined height. Liquid purified by sedimentation is suctioned off from the upper end of the sedimenting vessel by means of a jet pump (28).
