JPH0569562B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a vacuum filtration method for solid-liquid separation of materials to be treated that exhibit a liquefaction phenomenon, such as thixotropic and difficult-to-filter liquids, such as iron oxide, silicates, and salt. Regarding. "Conventional technology" Conventionally, when filtering and dehydrating a liquid-containing material that is difficult to filter, it is necessary to wash the material that has been dehydrated once.
That is, it is known that if the material to be treated is dehydrated and filtered again after performing the revalving operation, the final moisture content will be further reduced and a good effect will be obtained. The reason for this is that the rate-limiting layer that forms within the material to be treated during the dehydration process increases filtration resistance and prevents the discharge of the filtrate, but by adding water, the rate-limiting layer swells. This is to destroy the material and make it easier to dehydrate the object. By the way, as a dehydration/filtration method involving the above-mentioned revalving 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 compressing and dehydrating, water is added, a revalving operation is performed, and the filter press is applied again to obtain a final dehydrated cake. ``Problems to be Solved by the Invention'' However, in the above-mentioned conventional pressure filtration method that involves revalving, the process is a batch process, and after dehydration, the produced cake is temporarily removed from the filter. After being carried out and subjected to a revalving operation, it is necessary to perform compression filtration using another pressure filtration means, which poses problems in that the operation is troublesome and time consuming, and the workability is poor. Furthermore, it is possible to apply the above-mentioned revalving 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 bolus structure, by adding water, even if this water reaches the surface of the substance with the bolus structure, it will not act on the water contained in the bolus structure. This means that the water contained therein is not discharged to the outside during dehydration, and therefore the dehydration effect is not improved. The present invention was made in view of the above circumstances, and
The purpose is to provide a vacuum filtration method that allows continuous dehydration filtration when dehydrating and filtrating difficult-to-filter substances, and which has an extremely high dehydration effect. "Means for Solving the Problem" In order to achieve the above object, the first invention provides a method for applying water to the object to be treated after vacuum suction is applied to the object to be treated on the filter cloth. , an operation of adding a solvent, etc. and/or a stirring operation is performed, and then vacuum suction is performed.The second invention is a method in which, after vacuum suction is applied to the object to be treated, the object to be treated is removed through a filter cloth. Supplying compressed air to the processed material and stirring the processed material,
Next, vacuum suction is performed. "Operation" In the vacuum filtration method of the present invention, the material to be treated on the filter cloth is dehydrated under vacuum to form a cake, and then the vacuum state is released and the formed cake is directly stirred and destroyed. However, by adding water and a solvent, the water contained in the substances in the cake as well as the bound water between the substances are returned to a free state. Also,
In the non-vacuum process, by supplying compressed air to the material to be treated, together with stirring, the separation of lumps or granules of the material to be treated is promoted, and the filtration resistance during the next filtration is reduced. "Embodiment" Hereinafter, an embodiment 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, and this flat vacuum filtration device is supported by a large number of intermediate rolls 1, The material to be treated (slurry) 5 is supplied from the slurry inlet 4 onto the endless filter cloth 3 which travels in one direction by the filter cloth, and is provided at the lower part of the horizontal portion 3a of the filter cloth. The dehydration zone A that performs dewatering and filtration by suction and the plate-shaped body 8 of the non-vacuum zone B provided between each dehydration zone A are reciprocated along the rail 7 by the tray drive cylinder 6, and the above-mentioned By operating the revalve section 9 in the non-vacuum area B provided at the upper part of the horizontal portion 3a, dehydration is achieved into a cake, and the cake is scraped off from the filter cloth 3 with a scraper 10. Note that 11 is a spray for cleaning the filter cloth 3. In the dehydration area A, 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 so as to be movable left and right. These vacuum trays 12 are connected to the vacuum system 13 by flexible vacuum hoses 13a, and
and the vacuum tray 12.
3b and a release valve 13c for releasing each vacuum tray 12 from the vacuum. Further, as shown in FIG. 2, the revalve section 9 is disposed within the movement range of the plate-like body 8, and is set to approximately half the length of the plate-like body 8. And, the revalve section 9 is
A partition plate 14 is provided on the upstream side and a downstream side with respect to the traveling direction of the filter cloth 3, and a stirrer 15 is provided between the partition plates 14 to scrape up the material 5 on the filter cloth 3 and stir it. It is arranged at an adjustable height. This stirrer 15 has a scraping tool 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. Further, the revalve section 9 is appropriately provided with a water supply device (not shown) for water injection at the upper part thereof, so that water can be supplied to the object to be treated on the filter cloth 3. Then, dehydrated area A and non-vacuum area B
and are arranged alternately, and as shown in FIG. 3, the dehydration area A is divided into a vacuum filtration area A ₁ and a washing area A ₂ . That is, in FIG. 3, the vacuum filtration section A ₁ , the washing section A ₂ , the non-vacuum area B, the washing section A ₂ , and the vacuum filtration section (dehydration section) A ₁ are arranged.
In addition, Figure 4 shows a vacuum filtration section with two units.
They are arranged as follows: A ₁ , cleaning section A ₂ , non-vacuum area B, cleaning section A ₂ , non-vacuum area B, cleaning section A ₂ , and vacuum filtration section A ₁ . In addition, 16 in FIG. 1 is a compressed air part which will be described later. To explain the method of the first invention using the horizontal vacuum filtration device configured as above, first, the material to be treated 5 supplied onto the horizontal portion 3a of the filter cloth 3 is
The filter cloth 3 is vacuum-suctioned by a vacuum tray 12 placed under the filter cloth 3 to be dehydrated. When the water is dehydrated to a certain extent, the material to be treated 5 on the filter cloth 3
Since it is in a stationary state, it gels. At this time, the filter cloth 3 is moved to the right in FIG. Since the vacuum trays 12 and the filter cloths 3 are moved to the right, the adhesion between each vacuum tray 12 and the filter cloth 3 is maintained well, and efficient vacuum suction is performed. Next, when the tray drive cylinder 6 reaches its full stroke (see FIG. 4), the vacuum in the vacuum tray 12 is released, the vacuum tray 12 and the filter cloth 3 no longer come into close contact, and the tray drive cylinder 6
As a result, the vacuum tray 12 returns to its original position together with the plate-shaped body 8 (see FIG. 3). After returning to the original position, vacuum suction by the vacuum tray 12 is performed again. On the other hand, the material to be treated 5 on the filter cloth 3 that has reached the lower part of the revalve section 9 is washed and then subjected to a stirring operation by the stirrer 15, and is supplied with water from the water supply device as necessary in the next step. This destroys the rate-determining layer in the object to be treated 5 that has been formed and fixed by the dehydration operation, acts on the encapsulated water that has been taken into the bolus structure of the object to be treated, and is effective for subsequent cleaning. The encapsulated water is then taken out to the outside. At this time, the total amount of washing water is managed, for example, by dividing the water into three, four, and three parts from the first stage to the second stage. Therefore, the dehydration areas A for the next process are arranged alternately.
The dehydration effect is further enhanced. To demonstrate the above effect using a concrete experimental example,
The processed material (slurry) 5 used as a sample was as follows: Slurry to be processed Sample per solid substance amount Washing magnification Resin slurry 20 to 30μ 10 times/DS At this time: This example (vacuum filtration) + (washing) + (stirring) +
(Washing) + (Dehydration): Comparison example Under the conditions of (Vacuum filtration) + (Washing) + (Dehydration),

[Table] We obtained the following results. 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. In this embodiment, a compressed air portion 16 is provided in the 8 portion of the plate-like body in the embodiment of the first invention. 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. , air is blown out from the bottom surface of the filter cloth 3. Furthermore, instead of the agitator 15, an agitator 2 is provided in which a linear body or a linear elastic body 20C is arranged spirally at the tip of a support 20b provided at appropriate intervals on the rotating shaft 20a.
0 is set. 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, in combination with stirring or water injection. Due to its drying ability, it weakens the surface tension of the water attached to the molecules, so in addition to improving the operating performance of the revalve section 9 that involves water injection,
This is a more effective pre-treatment operation before the dehydration process when water is not poured. In addition, in the non-vacuum area B, the stirrer 1
5, 20 stirring operation, water injection operation (not shown),
The dehydration effect in the next vacuum area (process) A is improved by appropriately combining the compressed air operation by the compressed air section 16. Further, in each of the above embodiments, the above-mentioned agitators 15 and 20 were used, but the invention is not limited to this. 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. A pair of left and right screw blades (raking tool) 30b are formed in reverse.
You may use the stirrer 30 consisting of. Further, as shown in FIG. 8, the scraping tool includes a plurality of scraping rods 3 attached to a rotating shaft 30a along its axial length.
0c in a radial manner, or as shown in FIG. As shown in the figure,
As shown in FIG.
It may also be one with f attached. Furthermore, as shown in FIG. 12, along the length direction of the rotating shaft 30a,
A continuous spiral screw rod 30h may be provided via the support rod 30g, or a plurality of scraping rods (plates) held by the support rod 30g may be provided as shown in FIG.
30i 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, the dehydration operation, water injection, stirring, and air supply operations are appropriately combined for the object to be treated on the continuously running filter cloth. In addition to the usual difficult-to-filter materials,
Even if the structure includes a bolus substance, dehydration can be carried out continuously and more effectively, and workability and dehydration ability can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of a non-vacuum area showing an embodiment of the first invention, FIG. 3 is a schematic explanatory diagram showing the positional relationship between the dehydration zone and the non-vacuum area, and FIG. 4 is a schematic explanatory diagram when they are arranged in two series. 5 is a schematic configuration diagram showing an example of a horizontal vacuum filtration apparatus for carrying out the method of the present invention, FIG. 6 is an explanatory diagram of a non-vacuum area showing an embodiment of the second invention, and FIGS. Figure 14 shows various scraping tools used in the present invention, Figure 7 is a side view with screw blades provided, Figure 8 is a side view with scraping rods radially provided on the rotating shaft, Figure 9 The figure is an explanatory diagram of a raking bar with a protrusion, Figure 10 is an explanatory diagram of a raking bar with a raking bar attached to it, Figure 11 is an explanatory diagram of a raking plate attached to a raking bar, and Figure 12 is an explanatory diagram of a raking bar with a raking plate attached. A side view of a rotating shaft with a spiral screw rod attached to it via a support rod, Figure 13 is a side view of a rotating shaft with a scraping rod (plate) attached to it via a support rod, and Figure 14 is a side view of a rotating shaft with a scraping rod (plate) attached to it via a support rod. It is a side view in which a plurality of screw rods are provided via a support rod. 3...Filter cloth, 5...Product to be treated (slurry), 9
... Revalve section, 12 ... Vacuum tray, 15 ...
Stirrer, 16... Pressure section, 20... Stirrer, A...
... Dehydration area, B... Non-vacuum area, C... Pressure air, 3
0... 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 for 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.