(1) Operation and maintenance of the filter
Proper operation of the filter is one of the important conditions for obtaining good dewatering efficiency and high productivity. In the production practice beneficiation plants should adhere Depending on the nature of the ore beneficiation tests on the product by dehydration, to determine the optimum operating conditions optimum filter operation management system and filter. For example, rotational speed, suitable solid particle size range, suitable and stable feed concentration and pressure difference, and the like.
In the production, the regeneration of the filter cloth should be done. If necessary, the filter cake of the filter should be washed. This not only makes the surface of the filter cake clean, but also prevents the filter cake from cracking and reduces the vacuum. If the crack occurs due to the shrinkage of the filter cake during the suction process, the method of increasing the rotation speed of the filter cartridge and forming a thinner filter cake layer can be used to reduce the cracking phenomenon; the pressure roller and the pressure belt can also be used for compression. Filter cake and fill the cracks.
Planned maintenance should be done in production. Improve the filter plate structure and the fixing method of the filter cloth, and find that the filter cloth should be replaced or repaired as soon as possible when the filter cloth is damaged. After the disc of the dispensing head is worn, it should be repaired and scraped in time to prevent air leakage and reduce the vacuum. Regularly check the smoothness of the pipette to prevent the pipe from being affected and affect the degree of vacuum.
(2) Ways to improve filtration efficiency
For the main factors affecting the filtration process, we can seek ways to improve the efficiency of the filter from the technical operation and technical management of the filter.
(1) Determine the appropriate pressure difference by experiment. It can be known from the above influencing factors that in general, when the pressure difference is not large, increasing the degree of vacuum can reduce the moisture of the filter cake. However, when encountering a slurry composed of fine particles, a large pressure difference causes the fine particles to be drilled into the pores of the filter cloth to cause clogging, so that the filtration speed is lowered within a certain period of time. The best way to do this is to use a minimum suction pressure as long as the pressure maintains the necessary filtration rate of the slurry and helps the filter cake reach a certain moisture requirement. At the same time, it is also possible to use a thin filter cake layer to filter and extend the filtration time to prevent clogging of the filter cloth. Different suction pressures can also be used to separately filter and further dewater the filter cake. For example, a lower pressure is applied in the filtration zone to ensure a larger porosity of the filter cake and a higher filtration rate; in the dewatering zone, a higher suction pressure is used to increase the compression force on the filter cake so that Excessively squeeze out the remaining water.
(2) Select a high efficiency and high strength filter cloth. A good filter cloth should ensure a high recovery rate of the solid phase material of the slurry, and the filtrate does not contain suspended particles; the filtration resistance is the smallest, and there is sufficient mechanical strength and chemical stability, corrosion resistance and long service life. It is not easy to block, easy to clean and replace; when the filter cake is thickened, the sediment can be firmly adsorbed on it, and it is easy to fall off when discharging.
(3) Using a filter aid for a slurry composed of a flat gelatinous solid, it is easy to deform and block the filter pores during filtration. A filter material, such as diatomaceous earth , activated carbon, paper foil, etc., which is hard and does not deform under ordinary pressure, may be preliminarily coated on the filter cloth. This type of precoat material is a filter aid. The surface of the filter aid has the ability to adsorb the colloid and prevent it from clogging the pores. After filtration, the filter aid is removed together with the filter cake. Sometimes, in order to change the particle size composition of the slurry solids, the filter aid may be uniformly mixed in the slurry and then fed to the filter. Or the coarse-grained beneficiation product and the fine-grained product are matched to the filter, and the coarse-grained material can function as a filter aid.
(4) Warming filtration to increase the filtration speed. The slurry is heated to reduce its viscosity and good filtration efficiency is obtained. The concentrator generally uses steam to heat the filter. Production practice has shown that, under otherwise constant conditions, the temperature at which the filter operates is proportional to the amount of pulp being processed. However, when the temperature is too high, the change in viscosity is not significant, but it is unfavorable to the equipment, the mechanical corrosion is intensified, and steam is wasted. The appropriate heating temperature must be determined experimentally.
(5) Increase the feed concentration and increase the solids throughput. Increasing the feed concentration can reduce the volume of filtrate that is required to be discharged per unit of filtration area. In addition, after increasing the viscosity of the slurry, the resistance of the filter cloth is lowered, and the filtration speed is increased, thereby shortening the filtration time and improving the filtration efficiency. To this end, measures to enhance the pulp concentration process are to be taken. The stability of the filter cake layer stability can improve the processing capacity of the filter.
(6) Use a flocculant. Fine-grained materials can increase the viscosity of the slurry, making filtration difficult. The addition of the flocculating agent allows the fine particles to be aggregated into a larger aggregate (floc), which increases the particle size and narrows the size range, thereby avoiding plugging of the pores. Commonly used flocculants are lime, sulfuric acid, starch and other synthetic agents. After the flocculant is added, the thickness of the filter cake can be increased, but the moisture of the filter cake cannot be lowered. Since the capillary water is still attached to the filter cake, this defect can be overcome by using a filter press.
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