Filter presses are discontinuous working pressure filters for the solid liquid separation of slurries. They are distinguished by their excellent separation quality and high achievable solid content in the filter cake.
A filter plate pack, formed by single filter plates, is arranged in a frame. The plate pack is closed and tightened by a hydraulic cylinder. Filter cloth are mounted on each individual plate, which form a filter chamber by their recessed body. Through a feed channel the slurry gets pumped into the filter chamber. While the solids remain on the filter cloth, the liquid departs through the drainage surface of the filter plate. The continuous feeding of the filter raises the solid concentration in the filter chamber and the filtration pressure. The feeding and the feeding pressure is maintained until a cake with the requested solid content is formed. Finally the filtration pressure gets released, the plate pack is opened and the filter cake gets discharged by separation of the filter plates with the plate transport mechanism.
Depending on the slurry characteristic and the process requirement it may be appropriate to use membrane filter elements. Here, the feeding of the filter press is stopped after approximately 70 % of the filling degree of the filter chamber. By inflating an elastic element (membrane) the chamber volume gets reduced and the required residual moisture is obtained by mechanical squeezing.