Selection of filter media for filter press

     I. Overview
         The filter medium is the heart of the filter press. Whether the filter medium matches the filtration mechanism of the filter press and the suspension directly affects the normal use and working efficiency of the filter press. Therefore, the selection of suitable filter media is the core of the filter press technology.

Although various filter media manufacturers provide a lot of technical information on the performance and selection methods of the filter media they produce, the choice of filter media used in the filter press still depends on the accumulation of long-term experience in the material filtration process and filtration experiments to determine. We have accumulated a wealth of experience and a large amount of experimental data in the selection of filter media, which can provide complete selection services for solid-liquid separation users.

2. Filter media suitable for plate and frame filter press
The filter medium selected for the plate and frame filter press is generally filter cloth, and some use cardboard or filter paper (cotton cake filter and plate and frame oil filter) as the filter medium. Filter cloths suitable for filter presses are classified by material, mostly synthetic fibers; by structure, they are mainly woven fabrics, fiber felts, cardboard, and filter paper. There are a lot of introductions to various literatures on fabric and non-woven filter cloth, and each manufacturer has detailed instructions on filter cloth.

The following focuses on a kind of filter cloth “high temperature setting (calendering) filter cloth” suitable for use in filter press. After high-temperature setting (calendering) of the filter cloth, the shape of the holes between the yarns changes from a front flared shape to an inverted flared shape.

When the unshaped filter cloth is filtered, solid particles (fine particles) are easily trapped in the bell mouth to block the filter channel, and cannot form a good bridging pore, which affects the filtering effect. The filter cake and the filter cloth stick together.

Affect the shedding of the filter cake and the washing of the filter cloth. After high temperature setting, the filter cloth has a smooth surface, stable pore structure, and is not easy to deform; the bell mouth forms a funnel shape, and solid particles will not be blocked; it can form a good bridging filter layer; the filtration accuracy is higher, and the filter cake falls off Easy, the filter cloth is easy to clean, and it improves the sealing between the filter plates, reduces the capillary leakage between the filter plates, and is more suitable for the operation of the automatic filter press.

The surface high-temperature shaping technology has a good effect on the treatment. Only the monofilament filter cloth can keep the processed structure stable and not deformed, but the impact resistance and tensile strength of the monofilament filter cloth are far lower than that of the multifilament filter cloth, and it is very easy to be damaged.

Therefore, the filter cloth manufacturer has produced a single-multifilament filter cloth to overcome the weakness of the monofilament filter cloth.

Use monofilament filter cloth as the retention layer and multifilament filter cloth as the support layer. The filter cloth produced by this processing technology is very suitable for the use requirements of the filter press on the filter cloth.

Three, the selection principle and method of the filter cloth of the plate and frame filter press
(1) Choose the material of the filter cloth according to the chemical and physical properties of the material. All filter cloth suppliers provide detailed technical information as much as possible, which can be referred to for selection.
(2) Select the permeability (large cut-off particle size) of the filter cloth according to the requirements of filtration accuracy.

The preliminary selection can be made with reference to the technical parameters such as the large cut-off particle size provided by the filter cloth supplier.

Although the filter cloth plays a very important role in the initial filtration accuracy of the filter press, the initial filtration accuracy is not as high as possible. It is only necessary to consider that the filtration accuracy can meet the low requirements.

After the filter press forms a filter layer after filtering for a period of time, the retention effect of the filter cloth is very small. The “filter layer” that really plays the role of fine filtering is the key to the use of filter press technology.

(3) The peeling performance of the filter cake. When choosing filter cloth, pay special attention to the peeling performance of the filter cake. The surface of the filter cloth is smooth and flat, the filter cake peels off quickly, the filtering operation time is short, and the efficiency is high.

The filter cake adheres to the filter cloth and is not easy to peel off, which will extend the operating time of the filter press and reduce the work efficiency. If you want to replace the filter cloth, it will take longer.

Nowadays, it is troublesome to replace the filter cloth of the widely used chamber filter press. Selecting monofilament filter cloth has better cake unloading performance than long multifilament and short fiber filter cloth, and selecting satin weave has better cake unloading performance than plain weave filter cloth.

(4) The performance of the filter cloth. When choosing a filter cloth, pay attention to choosing a filter cloth with good performance. The filter cloth with good performance can be washed directly on the filter press to reduce the number of cloth changes.

The filter efficiency of the replaced filter cloth is restored to more than 80% after simple treatment (drying, washing, etc.).

         Doyen specializes in providing belt press equipment for the Southeast Asian market. Welcome to visit our workshop and formulate a more scientific  plan based on the actual situation of your company. Welcome to visit joyce@doyenchina.com or visit https://www.doyenchina.com.