(1) Tube type external filter vacuum filter
Vacuum filter is cylindrical metal Ores especially ferrous metals concentrator plant most applications dewatering equipment. According to its unloading method, it can be divided into various types. Figure 1 is a continuous filtering device that can simultaneously perform operations such as filtration, washing, and cake removal in the same rotating device. The cylinder is a cast or steel plate welded cylinder whose outer surface is divided into a plurality of filter chambers by a grooved lattice plate. The filter cloth is covered on the grid plate. The lower part of the cylinder is immersed in the slurry tank and is rotated around the horizontal axis by the gear system. The size of the filter chamber should not be too wide, generally not exceeding 550 mm. The number is related to the diameter of the cylinder. When the diameter is large, the surface area outside the cylinder is large, and the number of filter chambers is correspondingly increased. Conversely, the number of filter chambers is reduced accordingly - for example, a typical 40 m2 filter has 24 filter chambers.
The outer filter type vacuum filter scrapes off the filter cake with a scraper. The filter cloth is fastened to the filter plate by means of a wire . These wires also serve to prevent the filter cloth from being scratched by the scraper. The outer filter vacuum filter has a stirrer in the slurry tank, which is located below the cylinder and is driven by the bevel gear and the chain. When the agitator is working, the slurry can be kept in suspension in the trough. The number of times of agitation depends on the nature of the material, and is generally 20 to 60 beats/min. For materials with a large particle size and coarse density, the number of stirrings can be large.
The dispensing head is an important part of the filter. The filtrate is discharged through it, and suction and pressure are alternately carried out during the filtration process, so that the slurry forms a filter cake, and is changed from a vacuum suction state to a compressed air blow state, thereby effectively controlling the order of the filtration operation. The dispensing head is divided into two types: planar contact type and cylindrical surface contact type. The cylindrical surface distribution head is not easy to repair after being worn, and is easily caught by the ore particles, and is applied less. Most filters use a flat distribution head. In order to facilitate maintenance, the distribution plate of the flat dispensing head and the gas disc are often made into consumables in direct contact. [next]
The cylindrical external filter vacuum filter can be divided into the following working areas according to the filter cake forming process. as shown in picture 2.
Filtration zone I. The cylinder in this zone is immersed in the slurry, and the filter chamber formed between the filter cloth and the grid plate is evacuated, and the filtrate is sucked into the filter chamber through the filter cloth, and then discharged through the dispensing head. The solid material and residual moisture are adsorbed on the surface of the filter cloth.
Suction zone II. In this zone, the remaining filtrate is drained and the filter cake is blotted dry.
Washing zone IV. In this zone, fresh water is sprayed on the filter cake by the tube 7, and after washing the filter cake, it is sucked into the filter chamber, discharged through the tube 3 together with the filtrate or separately discharged by the tube 4.
Blowing zone VI. In this zone, the filter chamber is in communication with compressed air, and the compressed air blows the filter cake to facilitate unloading.
Discharge zone VIII. In this zone, the filter cake is peeled off by the doctor blade.
In the figure, III, V, VII, and IX are non-working areas and are located between II, IV, VI, and VII. Therefore, when the filter chamber is changed from one zone to another, it does not communicate with each other.
The beneficiation product usually does not require washing, so when the concentrator uses a vacuum filter, the washing zone is incorporated into the blotting zone.
When the filter is rotated once a week, the circulation process of filtration, dehydration, blow drying and filter cloth cleaning is gradually completed under the adjustment of the dispensing head with the vacuum tube and the blast tube. [next]
(2) Cylinder type internal filter vacuum filter
The inner surface of the cylindrical internal filter vacuum filter is its filtering surface. The slurry is fed to the inside of the cylinder, and the coarse material is deposited on the filter cloth before the fine particles due to gravity. A coarse particle layer with a large gap is formed, and as the fine particle material is deposited, a "bridge phenomenon" occurs in the pore, so that fine particles having a diameter smaller than the pore can be stopped, thereby improving the filtration effect. In the cake layer filtration, the main function of separation is the filter cake layer, not the filter medium. Therefore, the cylindrical internal filter type vacuum filter can form a filter cake in addition to the vacuum effect, and can also obtain a high production capacity when filtering the material which is easy to settle by means of the sedimentation of the material. This is particularly suitable for the filtration of coarse-grained materials and magnetite which is particularly severe in magnetic agglomeration. In addition, the filter has a large filter cloth cleaning area, and the filter cake can be removed for a longer cleaning time to restore the permeability of the filter cloth.
The structure of the cylindrical internal filter type vacuum filter is shown in Figs. 3 and 4. The working principle is the same as that of the external filter type vacuum filter. The inner filter surface of the internal filter type vacuum filter is divided into a plurality of filter chambers, and the filter chamber is sucked and blown by a vacuum tube. The vacuum tube is connected to the dispensing head, and the dispensing head works in the same way as the external filter vacuum filter. The cylinder rotates for one week, and the circulation process of filtering, dehydrating, blowing, unloading, and cleaning the filter cloth can also be completed, as shown in FIG. [next]
There are two types of filter cake discharge methods for the cylindrical internal filter vacuum filter. One is to use a fixed chute with diabase lining to send the falling filter cake directly to the silo outside the silo. The discharge mode is convenient to operate, the structure of the device is simple, and the utility model is mostly used for a small filter; the other discharge mode is the discharge of the center belt conveyor. This unloading method works reliably, and it is easy to install the aggregate belt conveyor and the weighing scale when working in multiples.
The disadvantage of the cylindrical internal filter vacuum filter is that it is troublesome to replace the filter cloth, the body is large, and the working condition in the observation machine is inconvenient during operation.
