• Laboratory filter press
  • laboratory and pilot scale filter press for mineral processing industry

Lab filter press

Filter press is a kind of pressure filtration equipment that works intermittently. It applies to solid-liquid separation of various kinds of suspension. Its filter chamber is composed of (plate-frame type) filter frames of filter plates or composed of arranged (chamber-type) filter plates.

ZJH minerals produced laboratory filter press for mineral concentration or ore tailings filtration. We will design and produce accodring to client’s demand. Our filter press is a whole system, including the slurry feeding pump. It is convenient for the client to do laboratory and pilot scale test.

1. Introduction of Lab Plate Frame Filter Press

Filter press is a kind of pressure filtration equipment that works intermittently. It applies to solid-liquid separation of various kinds of suspension. Its filter chamber is composed of (plate-frame type) filter frames of filter plates or composed of arranged (chamber-type) filter plates. Under the action of delivery pump, press the suspension (feed liquid) into each filter chamber. Then use filter media (usually filter cloth, sometimes filter paper, filter membrane, etc) to separate the solid from the liquid. The chamber-type filter plates are then divided into common filter plates and diaphragm plates. The filter presses are widely used in the fields of petroleum, chemicals, pharmacy, sugaring, metallurgy, food, ceramics, starch, coal washing, dyeing, and painting and for sewage treatment in various industries.

The filter press series have 320, 450, 630, 800, 1000, 1250, 1500,Φ800, and Φ1000 plate-frame type and chamber-type ones. Their filtering area is 0.5m2 to 500m2. The plate frame can be made of cast iron, spheroidal graphite cast iron, reinforced PP, glass fiber PP (able to endure the temperature of 120℃), stainless steel, etc. The pressing forms include manual pressing, jack pressing, mechanical pressing, hydraulic pressing, automatic maintaining pressure pressing, and advanced minicomputer program control automatic control. The filtering forms include open flow, undercurrent flow, open flow that can be washed, undercurrent flow that can be washed, and two-way cross-washing. Polypropylene materials have characteristics such as stable chemical property, acid-alkali resistance, corrosion resistance, no toxin, no taste, no pollution, and easy operation.

2.Technical Parameter of Lab Plate Frame Filter Press

Manual jack pressing reinforced PP plate and frame filter press

3.Structure and Instruction 

Such filter press consists of four parts, i.e. main frame part, filtering part, pressing part and control system.
3.1. Main frame Part
The main frame is the basis of equipment which is used to support the filtering structure and connect other parts. It is composed of thrust plate, pressing plate, pressing frame, girder, etc. During operation, the lead screw (or piston rod) of pressing frame (or hydro-cylinder), under the action of pressure, jack up the pressing plate and filter plate, filter frame, and frame cloth, to ensure the feed liquid can be pressurized and filtered without any leakage in the filter chamber.
3.2. Filtering Part
The filtering part is composed of several filter plates and filter frames which are arranged on the girder in certain order. Between the filter plate and filter frame is clipped filter cloth.
The materials enter each filter chamber from the feeding mouth in the thrust plate. The solid particles are intercepted in the filter chamber since its particle diameter is larger than the gap of filter media and then form filter cake. The liquid is discharged from the liquid hole through the filter cloth. Liquid can be discharged through flow and undercurrent flow. There is a discharge hole below every filter plate. Besides, it is equipped with nozzle. Such method of discharging from the nozzle of every filter plate is called open flow. The filtering method of discharging out of the machine through a discharging passage when the filter liquid from each filter plate converges is called undercurrent flow.
The filter presses can be divided into washable filter presses and unwashable filter presses based on whether it is necessary to wash the filter cake. The filter presses for which the filter cake needs to be washed are called washable filter presses. Otherwise, they are called unwashable filter presses. There is one kind of plate in which inlet opening of washing liquid is designed. Such kind of plate is called filter plate with hole (or washing plate). There is the other kind of plate in which inlet opening of washing liquid is not designed. Such kind of plate is called filter plate with no hole (or non-washing plate). The washable ones are then divided into one-way washable ones and two-way (crossing) washable ones. The one-way washable filter plates, filter plates with holes, and filter plates with no holes shall be placed one by two. Two-way washable filter plates are all filter places with holes. However, the washing holes of two neighboring filter plates must be staggered. Washable ones are divided into open flow washable ones and undercurrent flow washable ones. Open flow washing refers to such process: Liquid holes are designed on the thrust plate and filter plate; the liquid passes the filter cake and is discharged from the filter plate with no hole. During two-way washing, first wash liquid from the side of filter press (one-way wash); then wash it from the other side. Open flow washing applies to materials that are pollution free, odorless, nontoxic, and non-volatile.
Undercurrent flow washable: The feeding and washing with undercurrent flow washing are similar to that with public flow washing. Only the liquid discharging methods are different. With this type, the feed liquid from each filter plate passes the discharging passage and converges before it is discharged. Undercurrent flow washable applies to materials that are easily volatile, toxic and harmful.
Open flow unwashable: With this type, all filter plates shall be free of hole. There is only one feeding passage with such type. The materials go into each filter chamber and liquid is discharged from each filter hole.
Undercurrent flow unwashable: With this type, all filter plates shall be free of hole. There is both feeding passage and discharging passage with this type. The liquid from each filter plate converges in one passage and is then discharged.
Membrane-type filter press is a kind of filter press developed from the common tank-type one. It replaces the common filter plates with some diaphragm plates which are placed between the common filter plates one by two. After filtration and washing, compressed air is inflated into the diaphragm plate to get the diaphragm (rubber or polypropylene) to bulge. Press the filter cake to get its liquid ratio to decrease significantly and improve separation effects. The pressing pressure is usually higher than the filtration pressure 0.1Mpa. The air-release valve must be shut during pressing but it must be opened during filtration. There is also open flow and undercurrent flow for membrane-type filter press. Its working principle for washing, drying, etc is the same as that of common tank-type filter press.
During the use of filter press, the filter medium (such as filter cloth) plays a critical role. Whether the performance and type of filter cloth are correct directly affects filtration effects. Among all those types of filter cloth being currently used, the most common one is textile filter cloth made of synthetic fiber. Its materials can be divided into terylene, vinylon, polypropylene, polyamide, etc and include cotton spinning cloth, nonwoven cloth, screen mesh, filter paper, microporous membrane, etc. Since the materials and knitting methods of filter cloth are different, their physical and chemical properties such as strength, elongation degree, air permeability, thickness, acid-resistance, and alkali-resistance also vary. The user can choose it according to the granular size, density, viscosity, pH value, chemical composition, and rated technological conditions of filtration of slurry, so as to get ideal interception effect and filtration speed. After the filter cloth has been used for a period of time, its meshes may be blocked by fine grains of materials, so as to affect filtration efficiency. Therefore, the filter cloth shall be flushed on a regular basis for reproduction or replacement.
3.3. Pressing Part
Pressing forms are divided into manual pressing, jack pressing, mechanical pressing, hydraulic pressing, and automatic pressure keeping pressing.
4. Control system
(1) Control system of automatic pressure keeping type
(2) Control system of program control automatic tie-plate type