Material filtration method of plate and frame filter press

1. When filtering different materials and the same material, the filtering effect (speed, water content) may also be different due to different water content and even different temperatures. Some materials even need to be adjusted by adding flocculant, calcium carbide slag and other filter aids before filtering Filtration characteristics of the material. Therefore, the filter cakes are not necessarily the same.

2. (1) Before filtration, check the filter cloth and filter plate. If flushing or blowing is required, check whether the flushing plate, the flushing hole and the blowing hole are unblocked.

(2) Whether the pressure is sufficient.

3 filters

(1) Open the filtrate outlet valve, start the feed pump, and gradually increase the apparent filtration speed and filtration time of the feed valve, so that the filtration pressure gradually increases, generally not more than 0.6Mpa (plate and frame type does not exceed 0.4Mpa). Filtration begins The filtrate may be turbid when the filter cloth does not have a pre-coating material, which can be used continuously. It will clear up naturally in the future. If there is a large leakage between the filter plates, the pressure can be increased appropriately. The filter cloth has capillary phenomenon, and it is normal for a small amount of filtrate to seep out.

(2) Monitor the filtrate. If the muddy water is found to be open flow, close the muddy water nozzle. If it is undercurrent, stop filtering. Check the filter cloth and repair or replace it.

(3) If a pneumatic diaphragm pump is used, the pressure reducing valve can be adjusted, the filtration pressure can be set at one time, and no one needs to operate during the filtration process. If a feed pump such as a screw pump is used, not only the return system should be installed, but also the filter pressure according to the filter pressure. Change the size of the return valve at any time to control the filter pressure, which requires someone to operate, otherwise the equipment will be damaged.

(4) The filtration pressure is high and the water output is small, which can be regarded as the end of the filtration and returns to the compression plate. If the moisture content of the filter cake is found to be high, the compression plate can be closed to continue filtration.

(5) If the filtration time is too long or the filter cake cannot be formed, consideration should be given to reducing the water content of the material, such as increasing the sedimentation time and increasing the concentration sedimentation tank or adding flocculants and filter aids (quick lime, diatomite and perlite) instead filter media.

(6) If the filter cake needs to be washed, close the water outlet on the washing plate, close the water inlet valve, open the washing water valve, and flush with water. The pressure of the flushing water is generally not greater than the rated filtration pressure of the equipment. The flushing time should be determined according to the flushing effect. .If the effect of one rinse is not satisfactory, you can rinse several times during the filtration process.

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