Process for concentrating a suspension

A process for concentrating a suspension, comprising the steps of:

• (a) providing 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, and said column having at least one tube axially disposed therein, extending from one end of said column toward the opposite end thereof, 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 column and the interior of the tubes;
• (b) supplying suspension to one end of the column;
• (c) removing concentrated suspension at said opposite end of the column;
• (d) removing liquid passed through said filter from the interior of each said tube;
• (e) 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;
• and
• (f) imparting pressure to 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.