Dry goods sharing: solutions to five kinds of common faults of belt filter press.

      No matter what kind of equipment, in the process of production and use, it will inevitably encounter a variety of problems, including the belt filter press. This paper summarizes the five types of common faults and solutions of belt filter press for your reference!

      The belt filter press is a kind of sludge dewatering and drying equipment used in the field of sludge treatment. The equipment is composed of two tensioned filter belts, which carry the sludge layer and pass through a series of regularly arranged roller cylinders in the shape of S. depending on the tension of the filter belt itself, the belt filter presses and shears the sludge layer to squeeze out the capillary water in the sludge layer to remove the material The mud cake with higher solid content can be obtained by water content in the pulp.

      The belt filter press mainly consists of: mixing device, distribution device, gravity dehydration device, wedge-shaped dehydration device, extrusion roller high-pressure dehydration device, automatic dosing system, air compressor, gas electric control system, etc. In the process of operation, once the cooperation between various parts fails, it is easy to fail, among which there are five common types, as follows:

1、 Filter belt deviation discount

      During the operation of the belt filter press, the belt often deviates and discounts. When the belt folds and the sludge scraper constantly rub against each other, the belt will break and the service life will be greatly shortened, which will bring great economic losses to the enterprise. Through the analysis, we found that the main reasons for the filter belt deviation discount are as follows.

1. The action of the correction roller is not sensitive

     The operation of the deviation correcting roller is not sensitive, which will make the filter belt run to one side. Once the limit switch fails, one end of the filter belt touches the frame of the dehydrator, it will turn over and break. In case of such a situation, if there is any damage to the air pipe or air bag, it shall be replaced in time; if the correction slider is rusted and jammed, it shall be derusted and lubricated; if the correction valve fails or the correction angle is not adjusted properly, it shall be repaired in time.

2. Incorrect position or partial wear of roller

      When the position of the press roll or the tension roll of the belt press is unbalanced, the interval between the rolls at both ends of the filter belt will change, which will cause the uneven stress on both sides of the filter belt, and the filter belt will deviate from the end with large stress to the end with small stress. Therefore, before the start-up of the belt filter press, it is necessary to carefully check whether the roller installation is balanced, which is easy to occur after the overhaul of the belt filter press; at the same time, regularly maintain the bearings and rollers, and timely repair if there is any wear.

3. Uneven mud distribution

      When the sludge is distributed unevenly after pre dehydration, the sludge will enter the pressing section, which will cause the cake on the filter belt to be thick and thin on one side, and the filter belt will shift to the thick side. The direction of migration force and correction force contradict each other, and the filter belt will break at the boundary of thick and thin mud layer. After the start-up of the equipment, it is necessary to carefully observe the sludge distribution of the filter screen. When the partial load is serious, it is necessary to clean the sludge inlet distribution facilities and adjust the position of the flat mud plate. If the mud rake is partially worn or not installed properly, it is necessary to check and repair the mud rake.

 2、 The filter belt is too dirty to wash

The filter belt is in a dirty state for a long time, and the washing is not clean, which will seriously affect the water permeability of the filter belt, resulting in abnormal sludge dewatering, poor desliming effect, and high water content of mud cake. The main reasons for this phenomenon are as follows.

1. Improper proportion or dosage of flocculant

The flocculation of sludge has a great influence on the dewatering effect. If the proportion concentration or dosage of flocculant is too high, not only the agent will be wasted, but also the permeability will be reduced due to the adhesion of filter belt. On the contrary, it also affects the dewatering of sludge. During the operation, the proportion and dosage of the agent should be adjusted properly according to the characteristics of the sludge and the water content of the sludge after concentration. At the same time, the mixing time of the flocculant should be extended as much as possible to make the solvent fully dissolved, so as to avoid the residual floccules blocking the pores of the filter cloth.

2. The pressure of flushing water is low, and the filter belt is not clean

In general, this situation is caused by water leakage of the flushing water pipe, failure of the flushing water pump, too much waste blocking of the backwashing filter screen, or blockage of the flushing filter belt nozzle. If the filter belt is not washed clean, it is easy to cause the filter hole to be blocked, affecting the filtering efficiency of the filter belt. In case of low flushing water pressure, check whether the pipeline of flushing water leaks or whether the flushing water pump fails, observe the change of pressure intensity of flushing water at any time, and clean the filter screen in time in case of blockage.

3、 Filter belt slipping

The slipping of filter belt is mainly caused by overload of mud feeding, insufficient tension of filter belt or flocculant sticking on the surface of driving roller, abrasion of supporting rollers or inflexible extrusion and rolling. At this time, it can be improved by reducing the amount of mud, and at the same time, check carefully whether each roller has inflexible rotation or local wear, so as to strengthen the lubrication effect of bearings and gears.

4、 Filter belt running mud

When the moisture content of sludge to be dehydrated is too high, the sludge will overflow from both sides of the filter screen in the operation process. The reason is that in the process of sludge changing from liquid to semi-solid, the liquid slurry has high fluidity, and the slurry will overflow from both sides of the roller. The common causes of mud running are as follows.

1. The flocculation effect of sludge is not ideal

If the sludge flocculation is not good, the capillary water will not be converted into free water and will be removed in the gravity area. Therefore, the flowing sludge will easily escape after being squeezed into the pressing area. To solve this problem, PAM solution can be added according to the flocculation of sludge and the moisture content of sludge cake.

2. The main reason is the low mud concentration

Sludge concentration refers to the solid content of sludge. When the solid content of sludge is lower than a certain degree, the dewatering performance of sludge is very poor and the dosage of flocculant will increase. When the sludge with low solid content enters into the belt filter press, there may be leakage of sludge and no pressure of the filter belt during operation. This problem can be solved by turning off aeration and increasing sludge concentration time as much as possible.

3. Arched filter belt

The filter belt arching is that the two filter belts wrapped on the roller surface do not coincide, the outer belt arching or the lower belt opening. The reason for the belt arching is that the internal tension of the belt is uneven, and the local tension is not enough to overcome the running resistance, which makes the belt loose. Solution: check the operation status of the adjacent rollers at the arch camber, maintain the bearings; check the tension system of the arch camber filter belt, reduce the resistance of the tension guide rod; adjust the tension air pressure to make the tension of the two filter belts moderate.

4. Excessive air pressure

When the flocculated material enters into the extrusion section, it will be squeezed out by strong pressure before it reaches a stable flow state. This is caused by the excessive pressure of the filter belt under the action of the cylinder. At this time, the air pressure should be adjusted to a proper range.

5、 The solid content of the treated cement cake is low

The low solid content of the dewatered sludge will not only make it difficult to remove the wet sludge stuck on the filter cloth and increase the difficulty of sludge dewatering operation, but also increase the cost of sludge treatment due to the high moisture content. The main reasons for the low solid content of sludge cake after sludge dewatering are as follows.

1. Belt speed is too fast

If the belt speed is too fast, it will cause that the belt filter press can’t press the sludge and stay for enough time in the pre dehydration period, which will make the mud cake thin and the solid content decrease. The solution is to reduce the belt speed.

2. Dosage or type of flocculant is not suitable

The wrong choice of flocculant will lead to the change of sludge properties or the amount of sludge, which will lead to the reduction of sludge dehydration. At this time, the test should be carried out again to select the appropriate flocculant type or dosage.

3. The tension of filter belt is too small

When the tension of filter belt is too small, the squeezing force of sludge is insufficient, so the solid content of cake after dehydration is reduced. At this time, the tension of the filter belt should be properly increased, and the pressure of the belt filter press is generally adjusted at 0.5-0.6mpa.

4. Filter belt blocked

If the filter belt is blocked, the water will not be filtered out and the moisture content of dewatered sludge will rise. At this time, stop the machine immediately and put the sludge on the filter belt into operation after flushing.

      We have different cases of mud pressing in mining industry in many countries. Welcome to visit our manufacturing workshop and work out a better sludge dewatering plan suitable for your company’s mining industry.Welcome to joyce@doyenchina.com or visit https://www.doyenchina.com.