A Filter Press consists of many plates and frames assembled alternately with the supports of a pair of rails or an overhead beam. The Filter press consists of a head and follower that contain in between a pack of vertical rectangular plates.
The head serves as a fixed end to which the feed and filtrate pipes are connected. The follower moves along the beams and presses the plates together during the filtration cycle by a hydraulic or mechanical mechanism. Each plate is dressed with filter cloth on both sides and, once pressed together, they form a series of chambers that depend on the number of plates.
The plates have generally a centered feed port that passes through the entire length of the filter press so that all the chambers of the plate pack are connected. The filtrate that passes through filter cloth is collected through the four corner ports connecting all the plates together.
A centrifuge pump ensures the delivery of the suspended solids into each of the separating chambers. The introduced slurry flows through a port in each individual frame, and the filter cakes are accumulated in each hollow frame. As the filter cake becomes thicker, the filter resistance increases as well. So when the separating chamber is full, the filtration process is stopped as the optimum pressure difference is reached.
The filtrate that passes through filter cloth is collected through collection pipes and stored in the filter tank. Filter cake (suspended solid) accumulation occurs at the hollow plate frame, then being separated at the filter plates by pulling the plate and frame filter press apart. The cakes then fall off from those plates and are discharged in a collection point.
An automatic filter press consists of larger plate and frame filter presses with mechanical "plate shifters". The function of the plate shifter is to move the plates and allow rapid discharge of the filter cakes accumulated in between the plates.