Filter presses is basically a device to separate solid from liquid under pressure and consisting of two fixed head pieces and a moveable pressure piece with chambers formed by plates and frames or recessed chamber plates in between the fixed head piece and the movable. Pressure piece is operated by a mechanical or a hydraulic closing device.

The plates are covered with filter cloths which serve as gaskets at the sealing rims and filter media in the areas of the recessed square surface. With the filter press closed, a number of cavities are formed in which the slurry to be filtered is pumped.

The filter press is fed through the inlet flange mounted at the head piece under pressure. The filtrate is either drained along a channel system formed by appropriate cored holes in the plate or through individual taps at each of the plates. When the filter cavities have been filled with the remaining solids, the amount of filtrate decreases up to predetermined stage. This may be followed by washing. Washing should be continued till the sample of wash water indicate that all mother liquor has been removed. The discharge of the solids is released by opening the closing device and by moving the pressure piece and plates. Distance of the opening corresponds to the opening stroke of the closing device and pressure piece.

Compared to other filtering equipments, the filter press holds more solids and have more filtering area with washing conveniences. The principle of all filter presses is basses on the fact that the pressure which is necessary for filtration is evenly distributed.