Apparatus for concentrating a suspension

Apparatus for concentrating a suspension comprising:

• a closed, 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, said interior defining a concentration zone extending axially from one end of the column to at least near the opposite end of the column;
• means for supplying suspension to said one end of the column;
• means for removing concentrated suspension at said opposite end of the column;
• at least one tube axially disposed in said column and extending from said one end toward said opposite end through said concentration zone, said at least one tube having an outer wall of constant diameter, and at least one filter, in said wall near said opposite end, forming the only direct communication between the interior of the column and the interior of the tube;
• means communicating with the interior of each said tube for removing liquid passed through said filter;
• means for controlling the relative rates of supplying suspension and removing concentrated suspension for maintaining a packed bed of concentrated suspension in said interior that extends axially from a position between said filter and said one end toward said opposite end through said concentration zone;
• and
• means acting on the liquid of said suspension for urging said liquid through said packed bed toward said filter, whereby the presence of the packed bed results in a liquid pressure differential between said one end and said filter, said pressure differential imparting a force on the packed bed toward said opposite end.