Abstract: An apparatus for separating solids suspended in incoming pressurized liquid slurry is disclosed. The apparatus comprises a vessel having an elongated cylindrical vessel wall, a closed upper end and a bottom section for accumulation of solids. The vessel includes a stirrer mounted for rotation along an inside surface of the bottom section and a discharge spool mounted beneath the bottom section including at least one opening. An underflow pump is provided for discharging separated solids without loss of pressure in the apparatus. The apparatus further includes means for detecting solids level in the apparatus, which preferably operates without disturbing settling of the solids therein. Also, the apparatus includes a feedwell for receiving an incoming pressurized slurry stream, the feedwell having an opening a predetermined distance above a level in the apparatus defined by settled solids.