JPS62125806A - Vacuum filtration method - Google Patents

Abstract

PURPOSE:To continuously dehydrate and filter and to obtain high dehydration efficiency when difficult-to-filter substances are dehydrated and filtered by applying an appropriate combination of dehydration, water injection, and air supply to a material to be treated on a continuously traveling filter cloth. CONSTITUTION:The endless filter cloth 3 is supported with many intermediate rolls 1 and traveled in one direction by a filter cloth driving drum 2. The material 5 to be treated on the filter cloth is temporarily vacuum-filtered to form cake. The vacuum is turned off, the cake is directly agitated and crushed, water and a solvent are added, hence the combined water between substances is made free along with the water contained in the cake. Besides, compressed air is supplied to the material 5 to be treated in a non-vacuum stage to promote the separation of the blocks or the granular bodies of the cake in cooperation with agitation, and the filtration resistance in the succeeding filtration is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention is directed to the solidification of materials to be treated that exhibit a liquefaction phenomenon, such as thixotropic and difficult-to-filter liquids, such as iron oxides, silicates, and common salt. This invention relates to a vacuum filtration method for liquid separation.

``Prior art'' Conventionally, when filtering and dewatering a liquid-containing material that is difficult to filter, it is necessary to wash the material that has been treated with water, that is, perform a repulping operation, and then dehydrate the material again. It is known that filtration has a positive effect by further reducing the final moisture content.

The reason for this is that the rate-determining layer that forms within the material to be treated during the dehydration process increases the 01 overresistance and prevents the discharge of the filtrate. This is to destroy the material and make it easier to dehydrate the material.

By the way, as a dehydration/filtration method accompanied by the above-mentioned repulping operation, a pressure filtration method has generally been used. That is, this is a method in which a filter press is used as a filtration machine, and after compression dehydration is performed, water is added to perform a repulping operation, and the final dehydrated cake is obtained by applying the filter press again.

``Problems to be Solved by the Invention'' However, in the conventional pressurized filtration method that involves the operation of the glue valve, the process is a batch process; After being transported outside and subjected to repulping, it is necessary to press and filter using a separate pressurized filtration means, which poses problems such as troublesome and time-consuming operations and poor workability.

It is also possible to apply the above repulping operation to a conventional horizontal vacuum filtration method, but in this case, it may not be possible to improve the dehydration effect. In other words, when the object to be treated has a porous structure, by adding water, even if this water reaches the surface of the porous structure of the object, it will not act on the water contained in the porous structure. Secondly, during dehydration, the encapsulated water is not drained to the outside, so the dehydration effect is not improved.

The present invention has been made in view of the above circumstances, and its purpose is to dehydrate and filter difficult-to-filter substances.
The purpose is to provide a vacuum filtration method that can perform continuous dehydration filtration and has an extremely effective dehydration effect. In the invention, after vacuum suction is applied to the object to be treated on a filter cloth, an operation of adding water, a solvent, etc. and/or a stirring operation to the object is performed, and then vacuum suction is performed. Yes, second
In the invention, after vacuum suction is applied to the object to be processed,
Pressure air is supplied to the object to be treated through a filter cloth to stir the object, and then vacuum suction is performed.

"Operation" In the vacuum filtration method of the present invention, the material to be treated on the filter cloth is once vacuum dehydrated to form a cake, and then the vacuum state is released and the formed cake is directly stirred and destroyed. While
By adding water and a solvent, the amount of bound water in the substance, including the moisture contained in the substance in the cake, is returned to a free state. In addition, in the non-vacuum process, by supplying compressed air to the object to be treated, together with stirring, the separation effect of lumps or granules of the object to be treated is promoted, and filtration resistance during the next filtration is reduced.

"Example" Hereinafter, an example of breeding of the first invention will be described based on FIGS. 1 to 5.

FIG. 5 is a diagram showing the overall structure of a horizontal vacuum filtration device for carrying out the method of the present invention. The material to be treated (slurry) is poured from the slurry inlet 4 onto the endless filter cloth 3 that travels in one direction.
5 and is provided at the lower part of the filter cloth horizontal portion 3a and performs dehydration filtration by suction, and each dehydration zone A
The plate-shaped body 8 in the non-vacuum area B and the tray 4 are not provided in between.
By moving the drive cylinder 6 back and forth along the rail 7 and operating the repulp section 9 in the non-vacuum area B provided at the top of the horizontal section 3a, dehydration is achieved and the cake is transferred to a filter cloth. 3 with a scraper 10. Note that 11 is a spray for cleaning the filter cloth 3.

In the dehydration zone AICk, as shown in FIGS. 1 and 5, a vacuum tray 12 for vacuum suctioning the upper surface of the filter cloth 3 is provided at the lower part of the horizontal portion 3a and is movable from side to side. There is. These vacuum trays 12 are connected to the vacuum system 13 by flexible vacuum hoses 13&,
Additionally, a cutoff valve 13b that cuts off between the vacuum system 13 and the vacuum tray 12 and a release valve 13c that releases each vacuum tray 12 from the vacuum are provided. Further, as shown in FIG. 2, the repulp section 9 is disposed within the movement range of the plate-like body 8, and is set to have a length that is half the length of the plate-like body 8. In the repulp section 9, a force is applied to the upstream side and a downstream side with respect to the traveling direction of the filter cloth 3, and the partition plate 14 is set to the side, and a stirrer 15 is placed between the two partition plates 14 on the filter cloth 3. The height of the object to be processed 5 can be raised and stirred. This stirrer 15 has a scraper 15c made of a flexible plate-like body removably attached to the tips of a plurality of support plates 15b protruding from a rotating shaft 15a. Furthermore, in the repulp section 9, illustrated in the upper part thereof,
A water supply device is provided as appropriate for water injection when the filter cloth 3
Water can be supplied to the objects to be treated above. and,
The dehydration area A and the non-vacuum area B are arranged alternately, and the third
As shown in the figure, the dehydration zone A is divided into a vacuum filtration section A1 and a washing section A2. That is, in FIG. 3, they are arranged as follows: vacuum filtration section Ax cleaning section A2, non-vacuum area B, cleaning section A2, and vacuum filtration section (dehydration section) A1. In addition, FIG. 4 shows a double series, in which the vacuum filtration section Al is arranged as a cleaning section A2, a non-vacuum area B1, a cleaning section A2, a non-vacuum area B, a cleaning section A2, and a vacuum filtration section A1. There is. In addition, 16Y'i in FIG. 1 is a compressed air section which will be described later.

To explain the first invention in detail using the horizontal vacuum filtration apparatus configured as described above, first, the material to be treated 5 supplied onto the horizontal portion 3a of the filter cloth 3 is It is placed in the vacuum tray 12 and vacuum-suctioned to dehydrate it. When the water is dehydrated to a certain extent, the filter cloth 3
Since the upper object to be processed 5 is in a stationary state, it becomes a gel. At this time, the filter cloth 3 is moved to the right in FIG. 5 by the filter cloth drive drum 2, but the vacuum tray 12 and the plate-shaped body 8
are moved to the right in synchronization with the filter cloth 3 by the tray drive cylinder 6, so that the adhesion between each vacuum tray 12 and the filter cloth 3 is maintained well, and efficient vacuum suction is performed.

Then, the stroke of the tray drive cylinder 6 becomes -
When the problem occurs (see FIG. 4), the vacuum in the vacuum tray 12 is released, and the vacuum tray 12 and the filter cloth 3 do not come into close contact with each other. It returns to its original position (see Figure 3), and when it returns to its original position, the vacuum tray 12 again performs vacuum suction. After being washed, the treated material 5 is subjected to a stirring operation by the stirrer 15, and water is supplied from the water supply device as necessary in the next step, so that the material 5 is formed and formed by the dehydration operation.
The rate-limiting layer of the fixed object to be processed 5 is destroyed, and it acts on the encapsulated water trapped in the porous structure of the object to be processed 5, and the encapsulated water is taken out to the outside by subsequent cleaning. At this time, for example, 3.4°3 from the front stage to the rear stage.
The total amount of water for washing is managed by supplying water separately. Therefore, the dewatering effect in the dewatering areas AIC of the #7+next process which are arranged alternately is further enhanced.

To demonstrate the above effect through a concrete experimental example, the material to be treated (slurry) 5 used as a sample is the slurry to be treated.
Sample average particle size per solid substance amount Washing ratio Resin slurry 20-30. rz
10 times/DS, and at this time, ■: This example (vacuum filtration) + (washing) + (stirring) + (
Washing) + (Dehydration) 1 Comparison Example Under the conditions of (vacuum filtration) + (washing) + (dehydration), the following results were obtained. Note that the substances recovered as impurities may of course be useful substances.

Further, in this embodiment, the process shown in FIG. 3 was used, but if the process shown in FIG. 4 is used depending on the situation, the impurity removal rate can be further improved.

Further, an embodiment of the second invention will be described based on FIGS. 1 and 6. This embodiment is compared to the embodiment of the first invention, in which a compressed air portion 16 is provided in 8 portions of the plate-like body. That is, the compressed air section 16 supplies pressurized air C through a pressure regulating valve 17 into a pressure chamber 18 formed at the top of the plate-like body 8, and through a perforated plate 19 installed at the top of the pressure chamber 18. , filter cloth 3
In addition, instead of the agitator 15, a spiral root ball or wire bullet is attached to the tip of supports 201) provided at appropriate intervals on the rotating shaft 20a. A stirrer 20 including a 20C is installed. By operating the compressed air section 16 to blow out air from below the filter cloth 3, the compressed air acts on individual molecules of the material to be treated 5 in all directions by competing with the stirring or water injection action. Its drying ability weakens the surface tension of water adhering to molecules, so in addition to the effect of improving movement performance in the repulp section 9 when water is poured, it is also a more effective pre-treatment operation before the dewatering process when water is not poured. In addition, in the above non-vacuum area BVcb, the stirrer is 15°20
stirring operation, water injection operation (not shown), and compressed air section 1
The dehydration effect in the next vacuum region (step) A is improved by appropriately combining the compressed air operations in Step 6. Further, in each of the above-mentioned Examples, explanations are made using each of the above-mentioned stirrers 15 and 20, but the following is not limited thereto. For example, as shown in FIG. 7, there is a rotating shaft 30a that is rotatably provided parallel to the width direction of the filter cloth 3 and rotated by a drive device 31, and a rotating shaft 30a that is attached to the rotating shaft 30a and that rotates in a spiral direction with respect to each other. It is also possible to use an agitator 30 consisting of a pair of left and right screw blades (raking tools) 30b that are formed in reverse order. Further, as a scraping tool, as shown in FIG.
As shown in the figure, a plurality of protrusions 30d are attached to the circumferential surface of the scraping rod 30C in a dotted, annular, or spiral shape, or as shown in FIG. It is also possible to use a scraping rod 30e attached to the tip or a scraping plate 30f as shown in FIG. 11.

Furthermore, as shown in FIG. 12, a continuous spiral screw rod 30h is provided along the length direction of the rotating shaft 30a via a support rod 30g, and as shown in FIG. A plurality of scraping rods (boards) 30 held in
i may be attached parallel to the axis of the rotating shaft 30a or obliquely and superimposed on each other, and as shown in FIG. The screw rods 30j may be appropriately provided so as to overlap each other and rotate in the same direction or in different directions.

"Effects of the Invention" As explained above, according to the present invention, dehydration operations, water injection, stirring, and
Since each air supply operation is appropriately combined, it is possible to dewater continuously and more effectively even if the material to be treated is not only difficult to filter, but also has a porous structure. It is possible to improve workability, dewatering ability, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG.
An explanatory diagram of the non-vacuum area showing one embodiment of the invention, FIG. 3 is a schematic explanatory diagram showing the positional relationship between the dehydration area and the non-vacuum area, and FIG.
5 is a schematic configuration diagram showing an example of a horizontal vacuum filtration apparatus for carrying out the method of the present invention, and FIG. 6 is a non-vacuum area diagram showing an embodiment of the second invention. , and Figures 7 to 14 show various scraping tools used in the present invention. Figure 7 is a side view with screw blades provided, and Figure 8 is a raking rod radially attached to a rotating shaft. Figure 9 is an explanatory diagram of the protrusions provided on the scraping rod.
Figure 0 is an explanatory diagram of a scraping bar attached to a scraping bar, Figure 11 is an explanatory diagram of a scraping plate attached to a scraping bar, and Figure 12 is an explanatory diagram of a spiral screw rod attached to a rotating shaft via a support rod. In the side view, Figure 13 shows a scraping rod (plate) installed on the rotating shaft via a support rod! FIG. 14 is a side view of a rotary shaft with a plurality of screw rods provided through support rods, 3.
...filter cloth, 5...material to be treated (slurry IJ-
), 9... Repulp section, 12... Vacuum tray, 15... Stirrer, 16... Pressure air section, 20... Stirring Machine, A: Dehydration area, B: Non-vacuum area, C: Pressure air,
30... Stirrer.

Claims (1)

[Scope of Claims] 1) In a vacuum filtration method in which a cake is formed on a filter cloth by vacuum suction and dehydration and filtration are performed, after applying vacuum suction to the object to be treated on the filter cloth, A vacuum filtration method characterized by performing an operation of adding water, a solvent, etc. and/or a stirring operation to a treated material, and then performing a vacuum suction. 2) In a vacuum filtration method in which a cake is formed on a filter cloth by vacuum suction to perform dehydration and filtration, after vacuum suction is applied to the object to be treated on the filter cloth, the object to be treated is removed through the filter cloth. A vacuum filtration method characterized by supplying pressurized air to a processed material, stirring the processed material, and then performing vacuum suction.