Decanter centrifuge

A centrifuge for the separation and recovery from an input sludge of at least a light phase and a heavy phase materials, comprising a rotatable elongated bowl, a rotatable coaxial screw conveyor within the bowl and having a hub supporting a plurality of helical flights defining a helical chamber extending between opposite ends of the bowl;

• discharging means near opposite ends of the bowl for said light and heavy phase material;
• and a baffle forming a partition within said bowl, said partition dividing said helical chamber into a separating zone having entry means for said sludge and connecting with said discharging means for the light phase material, and into a discharging zone connecting with said discharging means for the heavy phase material, and having an edge spaced from the bowl inner wall to provide a restricting passageway between said zones;
• and further comprising means for preventing blockage of said restricted passageway by a cake of heavy phase material including means for providing said baffle as a frame fixed between an adjacent pair of said helical flights, and having a displaceable flap sealably closed against said frame under centrifugal force in operation of the centrifuge and opened under pressure from said cake of heavy phase material to permit passage thereof from the separating zone to the discharging zone.