Working principle of belt filter

  The main working principle of a belt filter press can be divided into four stages, as follows:

  1. Pretreatment stage: The solid content of the raw slurry is generally very low. Gravity settling or other methods must be used to increase the slurry concentration to reduce treatment costs. A common pretreatment method is to mix the concentrated sludge with a polymeric flocculant. Under the action of the flocculant, the fine particles of the material agglomerate and initially settle, which is a prerequisite for sludge dewatering.

  2. Gravity dewatering stage: The flocculated pretreated sludge is added to the filter belt. Under the action of gravity, free water outside the flocs passes through the filter belt and is filtered out, reducing the water content of the sludge.

  3. Wedge pre-compression dewatering stage: After gravity dewatering, the sludge enters the wedge pressing section. The gap between the filter belts gradually narrows, and compression and shearing actions are applied to the sludge, causing it to dewater again. After this stage, the sludge almost completely loses its fluidity, thus ensuring that the sludge will not be squeezed out in the pressing dewatering section under normal conditions. 4. During the pressing and dewatering stage, the sludge undergoes repeated squeezing and shearing by a carefully designed pressing roller system, removing a large amount of capillary water and gradually reducing the moisture content of the sludge to form a sludge filter cake. At the separation point of the gravity separation filter belt, the filter cake is scraped off by the discharge scraper. After discharge, the filter cloth is washed and enters the next cycle.