Patent ID: 6890441

Claim:
Hydraulic annular washing column for continuously separating solids from a suspension comprising: a hollow cylindrical column having a central axis therethrough, said column having an interior with a cross-section, perpendicular to said axis, that is constant along said axis, and that extends from a first end to a second end of said column; one central cylinder axially disposed in said column and extending from said one end toward said opposite end, said central cylinder having an outer wall of constant diameter, said cylindrical column and said central cylinder defining an annular zone between them, extending axially from said first end of the column to at least near said second end of the column; at least one filter in said outer wall of said central cylinder, forming the only direct communication between said annular zone and the interior of the cylinder and at least one filter in the outer wall of said hollow cylindrical column; means for supplying a suspension to said first end of the column; means for removing suspension at said second end of the column; said annular zone defining a concentration zone and optionally a washing zone; means communicating with the interior of said central cylinder for removing liquid passed through said filter in said outer wall of said central cylinder and means for removing liquid passed through filter in the outer wall of said hollow cylindrical column; and hydraulic means, continuously acting on the suspension for urging the liquid through said annular zone towards said filters and for forming a packed bed of solids moving continuously in an axial direction towards said second end.