Device for compacting and draining fluid sludges containing fibrous materials

A device for compacting or settling aqueous sludge containing finely divided mineral and fibrous substances of organic or mineral origin after previous treatment by primary and secondary floculation of the sludge in its original liquid support, said apparatus comprising a vertical vessel including an upper cylindrical portion and a lower conical portion, a supply pipe for the sludge to be treated extending tangentially at a level below the top of the cylindrical portion of said vessel, a plurality of rotating perforated blades having a vertical axis installed in said cylindrical portion below said supply pipe, a conical rotating screw having a vertical axis installed in the conical portion of said vessel, said conical screw comprising means including at least one blade having a pitch correlated to the fibrous sludge to be treated so that compressed sludge at this level is not solidified and still contains interstitial water, said conical portion having a lower end with an outlet orifice thereat for compressed sludge, a spillway at the upper end of the cylindrical portion of said vessel for the discharge of a part of the interstitial water contained in the sludge, a horizontal cylindrical chamber secured to said conical portion of said vessel at the outlet orifice, said chamber including a downstream portion having a wall constituted as a grating for the discharge of remaining interstitial water contained in the sludge, a rotating screw installed in said chamber and extending beneath said outlet orifice, said chamber having an outlet orifice at an end thereof for discharge of compacted sludge, and flexible outlet means at said orifice having a conical shape and a free end with an outlet diameter which is smaller than its inlet diameter.