Filter operation process of plate and frame filter press

1. the use of plate and frame filter press to filter different materials and the same material because of the water content, or even the temperature, the effect of filtration (speed, water content) may be different, and some materials even need to add filter aid such as flocculant, calcium carbide slag, etc., before filtering, in order to condition the filtration characteristics of the material. So the cake is not going to be exactly the same.

2. (1) The plate and frame filter press should check the press cloth and filter plate before filtering. If washing or blowing is needed, the washing plate, the washing plate and the washing hole should be checked, and the blowing hole is smooth.

(2) Check whether the pressure of the filter press is enough.

3. filtration

(1) Open the filtrate outlet valve of the plate and frame filter press, start the feed pump, and gradually increase the apparent filtration speed and filtration time of the feed valve. The filtration pressure can be gradually increased, generally not more than 0.6Mpa (plate and frame type not more than 0.4Mpa). At the beginning of filtration, the filtrate may be cloudy, which is caused by the material not forming a pre-coating on the filter cloth, which can be continued to be used. It will clear naturally later. If there is a large leakage between the filter plates of the plate frame press, the compression force can be appropriately increased. Due to the capillary phenomenon of the press cloth, there will be a small amount of filtrate seepage, which is a normal phenomenon.

(2) Monitoring filtrate, such as the muddy liquid open flow is found to close the muddy water nozzle, dark flow can stop filtering, check the filter press cloth and repair or replace.

(3) If the pneumatic diaphragm pump can adjust the reducing valve, one-time set the filtration pressure, no human operation in the filtration process. If the feed pump such as screw pump is used, it is not only necessary to install the return system, but also to adjust the size of the return valve at any time according to the change of filtration pressure to control the filtration pressure. Someone needs to operate, otherwise it will damage the equipment.

(4) When the filtration pressure of the filter press is large and the water outlet is small, it can be regarded as the end of filtration and return to the pressing plate. If the water content of the filter cake is found to be large, the pressing plate can be closed to continue filtering.

(5) If the filtration time is too long or the filter cake can not be formed, the water content of the material should be reduced, such as increasing the precipitation time to add a concentrated sedimentation tank or adding flocculant and filter aid (quicklime, diatomite, perlite) to replace the filter medium and other solutions.

(6) If the filter cake needs to be washed, close the outlet on the washing plate in the open flow, close the feed valve, open the washing water valve, and drain the water for washing. The pressure of the washing water is generally not greater than the rated filtration pressure of the equipment. The washing time should be determined according to the washing effect.

(7) In order to reduce the moisture content of the filter cake, the compressed air drying method can be used. The method is the same as the flushing method. The feed hole intake method can also be used or the diaphragm filter press can be used.