The working principle of the filter press

  The working principle of a filter press mainly involves applying pressure to effectively separate the solid particles from the liquid in the mixture. Its working process is typically divided into four main stages: pre-pressing, filtration, backwashing, and unloading.

  During the pre-pressing stage, the filter cloth of the filter press is fully soaked and low pressure is applied to it to form a uniform solid pre-press layer. The purpose of this step is to prevent the filtering substances from being squeezed during the subsequent filtration process, which could cause the filter layer to rupture. In the filtration stage, the filter press applies high pressure to allow the mixed substance to pass through the pre-press layer and enter the filter cloth. The liquid part of the mixture passes through the filter cloth and flows out, while the solid particles are retained by the pores on the filter cloth, forming a filter cake.

  After a certain period of the filtration process, the pores on the filter cloth will gradually be clogged by the solid particles, affecting the filtration efficiency. At this point, the filter press enters the backwashing stage, where it reverses the water flow over the filter cloth to remove the solid particles that have clogged the pores, restoring the filter cloth's filtering ability. After the filtration cycle is completed, in order to loosen the filtered solid particles from the filter bed, the filter press reduces the pressure, opens the filter cloth, and vibrates the filter plates back and forth to completely loosen and accumulate the solid particles in the designated container.

  In addition, many modern filter presses are equipped with auxiliary devices such as automatic plate shifters with rapid movement to accelerate the removal of the filter cake and the overall filtration cycle time. These devices enable the filter press to operate continuously, meeting the needs of large-scale industrial production.