The main difference between the diaphragm filter press and the ordinary box filter press is that an elastic membrane diaphragm is installed between the filter plate and the filter cloth. During the operation, when the feed is finished, the high-pressure fluid medium can be injected between the filter plate and the membrane. At this time, the entire membrane will bulge the filter cake, thereby further dewatering the filter cake, that is, press filtration.
The first is positive pressure and pressure dewatering, also known as slurry dewatering, that is, a certain number of filter plates are closely arranged in a row under the action of strong mechanical force, and a filter chamber is formed between the filter plate surface and the filter plate surface, and the filter material is strong. The positive pressure is sent to the filter chamber, and the solid portion of the filter material entering the filter chamber is trapped by a filter medium (such as a filter cloth) to form a filter cake, and the liquid portion is filtered through the filter medium to discharge the filter chamber, thereby achieving the purpose of solid-liquid separation. With the increase of positive pressure, solid-liquid separation is more thorough, but from the perspective of energy and cost, too high positive pressure is not cost-effective. After the slurry is dehydrated, a filter press equipped with a rubber extruded film is used, and a compressed medium (such as gas or water) enters the back surface of the extruded film to push the extruded film to further dehydrate the extruded filter cake, which is called extrusion dehydration. After the slurry is dehydrated or squeezed and dehydrated, the compressed air enters the filter cake side of the filter cake through the filter cake, and the liquid water is carried out from the other side of the filter cake through the filter cloth to discharge the filter chamber to be dehydrated. If the filter cloth is applied to both sides of the filter chamber, the liquid portion can pass through the filter cloth on both sides of the filter chamber and exit the filter chamber to dewater the filter chamber.
After the dewatering is completed, the mechanical pressing force of the filter plate is released, and the filter plate is gradually opened by a single piece, and the filter chamber is opened separately to perform the unloading of the cake as a main working cycle. Depending on the nature of the filter material, the filter press can be separately set into slurry dewatering, extrusion dewatering, wind blowing dehydration or single and double side dewatering, in order to minimize the filter cake moisture.