JPH10309409A - Vacuum filtration apparatus and filtration method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical vacuum filtration apparatus having high dewatering property. SOLUTION: In a vacuum filtration apparatus which carries out filtration of a slurry by running a filtration cloth 1 on which a slurry is supplied while bringing the cloth 1 into contact with the upper sides of vacuum boxes 2, 2..., a pair of squeezing rolls 3, 4 are installed in the upper face side and in the lower face side while sandwiching the filtration cloth 1 in a section from a position where the filtration cloth 1 and the vacuum boxes 2, 2... are parted from each other to the position where the cake C4 formed by the filtration is discharged out of the cloth 1 and cylinders 19, 19 to pressurize the lower side squeezing roll 4 toward the upper side squeezing roll 3 are installed and the filtration cloth 1 is run by driving the upper side squeezing roll 3. Moreover, side end pressurizing rolls 30, 30 to push both side end parts of the filtration cloth 1 to the upper side squeezing roll 3 in the operation initial period are also installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filtering machine and a filtering method using the same, and more particularly, a pair of squeezing rolls are provided on the upper and lower surfaces with a filter cloth supplied with slurry on the upper surface. TECHNICAL FIELD The present invention relates to a vacuum filter characterized by a point and a filtration method using the same.

[0002]

2. Description of the Related Art This type of vacuum filter mainly includes a type in which vacuum suction of a vacuum box is continuously performed and a type in which vacuum suction of a vacuum box and opening to the atmospheric pressure are repeated. As a type in which vacuum suction is continuously performed, there is a type in which a filter cloth is supported by a porous endless rubber (or plastic) belt and runs on a vacuum box.

As shown in FIG. 5 of Japanese Patent Application Laid-Open No. 4-227807, a plurality of vacuum boxes are connected endlessly, and an endless filter cloth is arranged outside the vacuum boxes. There is a filter that performs vacuum filtration while circulating in the same direction.

On the other hand, a type which repeats vacuum suction and release to atmospheric pressure includes, for example, a horizontal belt filter device described in Japanese Patent Publication No. 55-26886. In this apparatus, a vacuum box having an open top is fixedly arranged, and a filter cloth is provided in contact with the top of the vacuum box. This apparatus repeats vacuum suction of a vacuum box and opening to the atmospheric pressure by switching valves, and intermittently filters by moving a filter cloth at the time of opening to the atmospheric pressure.

As the same type, for example,
There is also a filtration device described in JP-B-55-33368. In this apparatus, a vacuum box having an open top is provided so as to be able to reciprocate, and a filter cloth is provided in contact with the top of the vacuum box. This device moves the filter cloth and the vacuum box in the same direction and at the same speed during vacuum suction of the vacuum box, and when the vacuum box has moved a fixed distance, returns the inside of the vacuum box to atmospheric pressure by switching the valve, The vacuum box is quickly returned to its original position.

In these vacuum filters, the liquid contained in the slurry or cake on the filter cloth is suctioned from the lower side of the filter cloth by maintaining the vacuum pressure in the vacuum box at a maximum of about 1 kg / cm ^2. Filtration was performed, but the liquid removal property was not so high.

Therefore, there is a problem that it is necessary to further remove the liquid depending on the type of the filtered product.

In order to solve such a problem, Japanese Patent Laid-Open Publication No.
In Japanese Patent No. 27807, a vacuum box having an open top is provided so as to be capable of reciprocating operation, a filter cloth is provided in contact with the upper surface of the vacuum box, and a liquid is permeated. Further, a pressure roller for cake is provided above the filter cloth. A provided filter is proposed (hereinafter referred to as Prior Example 1). In this filter, the filter cloth and the vacuum box are relatively stationary, that is, the filter cloth and the vacuum box are moving in the same direction and at the same speed, and the filter cloth and the vacuum box are stationary. Occasionally, the slurry supplied on the filter cloth is subjected to suction filtration from the lower side of the filter cloth by applying a negative pressure to the vacuum box to form a cake on the filter cloth. Pressure filtration is performed by a pressure roller.

Also, in Japanese Utility Model Publication No. 8-4088, the applicant supplies slurry to the upper surface of the filter cloth, performs suction filtration from the lower side of the filter cloth by applying a vacuum to the suction box, and places the cake on the filter cloth. Has been proposed, and a horizontal vacuum filter for performing pressure filtration on the cake using a pressure plate provided above the filter cloth has been proposed (hereinafter referred to as Prior Example 2).

[0010]

However, in the prior art 1, when the vacuum box is returned to the original position, the pressure roller must be separated from the filter cloth. When running, the solid-liquid mixture could not be pressure filtered over the entire surface. On the other hand, the prior art example 1 proposes stopping the travel of the filter cloth when returning the vacuum box to the original position, but in this case, there is a problem that the filtration efficiency is reduced. Was.

In the first prior art, in order to improve the liquid removal rate, it is necessary to increase the pressing pressure of the pressure roller. However, if the pressing pressure is excessively increased, the tension of the filter cloth increases and the filter cloth may be damaged. There was. Therefore, prior example 1
With the apparatus described above, it was not possible to further improve the dewatering property.

Further, in the prior example 1, it is proposed to provide a device for synchronizing and moving the filter cloth and the vacuum box at the same speed in order to press the pressure roller against the upper surface of the vacuum box. However, providing such a device is not preferable because it leads to an increase in the cost of the entire device.

Further, in the prior art example 1, since the pressure roller is provided within the moving range of the vacuum box and presses the cake directly, the cake is not held on the filter cloth and the pressure roller is pressed. When it adheres, there is a problem that the inside of the vacuum box becomes atmospheric pressure. As a result, there is a problem that the cake on the vacuum box is not filtered by vacuum suction. On the other hand, prior example 1
Proposes to wind a pressure belt on the cake and the pressure roller to prevent the cake from adhering. However, in addition to the pressure belt itself, a meandering correction device or the like for ensuring the running stability of the pressure belt is proposed. Ancillary equipment is required, and increase in equipment cost is unavoidable. Further, cakes may adhere to the pressure belt depending on the kind thereof, and therefore, it is necessary to provide a cleaning device for the pressure belt, a scraper device for peeling off the adhered matter, and the like, which causes a further increase in the cost of the device.

On the other hand, in the prior example 2, since pressure filtration is performed using a flat plate, filtration can be performed only intermittently, and the filtration efficiency is fundamentally low. .

Further, in the prior example 2, in order to perform pressure filtration over the whole cake using a flat plate, the rear end portion of the object to be processed once subjected to pressure filtration is added again in the next pressure filtration. I have to press. For this reason, a reduction in filtration efficiency has been a problem.

Further, in the second prior art, in order to apply a constant pressure to the entire flat plate, a correspondingly large pressure must be applied. Therefore, there have been problems in that it is difficult to apply the present invention to a filter provided with a filter cloth having a large width, and that a large-sized pressure source is required, thereby increasing the cost of the apparatus.

Therefore, a main object of the present invention is to solve the problems in the preceding examples and to provide an inexpensive vacuum filter having a high liquid removal property.

[0018]

A vacuum filter according to the present invention, which has solved the above-mentioned problems, comprises a filter cloth and a vacuum box, and the filter cloth supplied with slurry on the upper surface is placed on the vacuum box. In a vacuum filter that filters the slurry by running in a state where the filter cloth is in contact with the filter cloth, a position at which the filter cloth and the vacuum box are separated from each other, and a position at which a cake generated by the filtration is discharged from the filter cloth. In the meantime, a pair of squeezing rolls is provided on the upper surface side and the lower surface side with the filter cloth interposed, and at least one squeezing roll of the pair of squeezing rolls is directed toward the other squeezing roll opposed to this. A pressurizing means for pressurizing is provided.

In this vacuum filter, means for bringing both ends of the filter cloth into pressure contact with the pressing roll on the upper surface side of the filter cloth may be provided, or at least one of the pair of pressing rolls may be provided. It is preferable to provide a driving means for rotating the pressing roll.

On the other hand, a filtration method using the vacuum filter of the present invention is also proposed. That is, the invention according to claim 4 is a filtration method using the vacuum filter according to claim 2, wherein at least until the starting end of the cake passes through a pressing position by the pair of pressing rolls, the filtration method is performed. The invention is characterized in that both ends of the filter cloth are brought into pressure contact with a pressing roll on the upper surface side of the cloth.

The invention described in claim 5 is the same as the invention described in claim 2.
A filtration method using the vacuum filter according to the above, until the starting end of the cake passes through a pressing position by the pair of pressing rolls, without performing the pressing by the pair of pressing rolls, the upper surface of the filter cloth Side of the filter cloth, the both ends of the filter cloth are brought into pressure contact with each other, and when the starting end of the cake passes through the pressing position by the pair of pressing rolls, the upper side of the filter cloth is pressed against the pressing roll. The pressurizing contact between both ends of the filter cloth is released, and pressing by the pair of pressing rolls is started.

In these filtration methods, it is preferable that at least one of the pair of pressing rolls is rotated so that the filter cloth runs.

<Operation> In each of the above-mentioned prior examples, the cake on the filter cloth is pressurized by a pressurizing means such as a pressurizing roller on the moving area of the vacuum box. Are performed in parallel. Therefore, pressurization can be performed only when the filter cloth and the vacuum box are moving in the same direction and at the same speed.

In the present invention, the idea is completely different from those of the preceding examples, and vacuum filtration and pressure filtration are not performed in parallel. That is, the vacuum filter of the present invention, between the position where the filter cloth and the vacuum box are separated, from the position where the cake generated by vacuum filtration is discharged from the filter cloth, the upper side and the lower side of the filter cloth The solid-liquid mixture after the completion of the vacuum filtration is further subjected to pressure filtration by a pair of pressing rolls provided on the side. Therefore, there is substantially no restriction such as pressurizing only when the filter cloth and the vacuum box are moving in the same direction and at the same speed as in the above-described prior example, and the filtration can be performed continuously. it can.

Further, the vacuum filter of the present invention has a simple apparatus configuration and is excellent in terms of apparatus cost, reliability and dewatering properties.

[0026]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a flow sheet of a vacuum filter according to the present invention. Compared with a conventional vacuum filter in which a vacuum box reciprocates, a filter cloth is provided on the exit side of a filter cloth 1 of vacuum boxes 2, 2,. A pair of squeezing rolls 3, 4 are provided on the upper and lower sides of
4, the cake C2 after vacuum filtration is further filtered under pressure.

First, the configuration of the apparatus will be described in detail. An endless filter cloth 1 is wound around return rolls 5A, 5B, 5C and 5D. In the upper traveling path of the filter cloth 1, the vacuum boxes 2 and 2 having an open upper surface in contact with the lower surface of the filter cloth 1. Are interconnected and arranged. Wheels 2a, 2a are provided on the lower surfaces of the vacuum boxes 2, 2,... So as to be movable on the rail 7 in the direction in which the filter cloth runs, and air is supplied to the vacuum box 2 at one end (left side in the figure). The cylinder 6 is connected. Are connected to the storage tanks T1, T2, T3 by pipes 8a, 8b, 8c. The storage tanks T1 and T2 are connected at an upper portion thereof to a vacuum suction pump P5 via a pipe 9 and at a lower portion thereof to liquid discharge pumps P1 and P2 via pipes 11a and 11b. Similarly, the upper part of the storage tank T3 is connected to a vacuum suction pump P5 via a pipe 9, while the lower part thereof is connected to a pipe 1
It is connected to the primary cleaning liquid circulation pump P3 via 1c.

In the filtration device of the present embodiment, a slurry supply device 12 is disposed at the start end of the vacuum boxes 2, 2,... At a position facing the upper surface of the filter cloth 1 in the upper traveling path. In the traveling direction 1, the cake washing liquid supply devices 13a and 13b are arranged at appropriate intervals. The front cleaning liquid supply device 13a is connected to the output side of the primary cleaning liquid circulation pump P3 via a pipe 10a, and the rear cleaning liquid supply device 13b is connected to the filter cloth cleaning device 40 via a pipe 10b.
It is connected to the outlet side of a secondary cleaning liquid circulation pump P4 that circulates the cleaning liquid collected in (described later).

Further, an upper pressing roll 3 and a lower pressing roll 4 are arranged on the end side of the upper traveling path of the filter cloth 1 so as to face each other, and pass through the vacuum filtration areas of the vacuum boxes 2, 2,. The configured filter cloth 1 is configured to be guided between the upper pressing roll 3 and the lower pressing roll 4.

As shown in FIGS. 2 and 3, the upper pressing roll 3 is rotatably supported on the upper frame 15 by a rotating shaft 3a and a bearing 3b, and is connected to a rotary drive source (not shown). . Characteristically, the guide roll 14 and the return roll 5B are arranged before and after the upper pressing roll 3, so that the lowermost part of the upper pressing roll 3 is lower than the uppermost part of the guide roll 14 and the return roll 5B. Is configured. Due to such a positional relationship, the filter cloth 1 is moved to the upper pressing roll 3 in accordance with the tension.
In a pressurized state. In order to achieve such a positional relationship, the upper pressing roll 3 is connected to the upper frame 1.
5 can be adjusted to any height.

On the other hand, the lower squeezing roll 4 has the lever 1 by the rotating shafts 4a, 4a and the bearings 4b, 4b.
It is rotatably supported on 6,16. Lever 16, 16
The pins 18, 1 are located on the rear end side (left side in the figure) of the projections 17 A, 17 A provided on the vertical frames 17, 17 (only one is shown) on the rear side of the position where the lower pressing roll 4 is disposed.
8 (only one is shown), it is rotatably supported, and the rear ends thereof are connected to the distal ends of piston rods 19a, 19a of cylinders 19, 19, respectively. The cylinder rear ends 19b, 19b are rotatably connected to the lower frame 20. Accordingly, the lower pressing roll 4 is moved by the contraction operation of the cylinders 19, 19.
Is pivoted about the pins 18 and 18 so that the tip side provided with is moved toward the upper pressing roll 3, and conversely,
By the extension operation of the cylinders 19, 19, the distal end side provided with the lower pressing roll 4 rotates about the pins 18, 18 so as to be separated from the upper pressing roll 3.

Further, in the apparatus of this embodiment, as shown in FIG. 4, a pair of side end pressing rolls 30 and 30 are used as means for bringing both ends of the filter cloth 1 into press contact with the upper pressing roll 3.
Is provided. These side end pressing rolls 30, 30
5 is rotatably supported on levers 16 and 16 so as to be located below both side ends of the filter cloth 1 as shown in detail in FIG. 30a is a rotation shaft of the side end pressing roll, and 30b
Is the bearing.

In the illustrated example, the lower pressing roll 4 and the side end pressing roll 30 are provided on the same lever 16, and the filter cloth 1 and the upper pressing roll 3 are moved by the contraction operation of the cylinders 19, 19. At the end side of the contact area, the filter cloth 1 is pressed against the upper pressing roll 3 by the lower pressing roll 4, and the side end pressing rolls 30, 30 are separated from the upper pressing roll 3, and conversely, the cylinders 19, 19
, The filter cloth 1 on the upper pressing roll 3
The side end pressing rolls 30, 30 are pressed to the contact start position of the lower pressing roll 4, and the lower pressing roll 4 is
It is comprised so that it may be separated from.

In addition, in the vacuum filter of this embodiment,
A scraper S1 for peeling the cake adhered to the upper pressing roll 3, a scraper 2 for peeling the cake from the filter cloth 1, and a filter cloth for cleaning the filter cloth 1 after discharging the cake in a lower traveling path of the filter cloth 1. A pair of tension adjusting rolls 50, 50 for guiding the filter cloth 1 in an S-shape on the lower traveling path of the washing apparatus 40, similarly to the filter cloth 1 (by adjusting the horizontal separation distance between the filter cloth 1 and the filter cloth 1). To adjust the tension). The cleaning liquid collected by the filter cloth cleaning device 40 is circulated and used by the secondary cleaning liquid circulation pump P4 to the cake cleaning liquid supply device 13b on the rear side.

In the filter described above, in order to filter the solid-liquid mixture, first, a rotary drive source (not shown) is operated to drive the upper pressing roll 3, and the filter cloth 1 is circulated clockwise in the figure. On the other hand, the inside of the vacuum boxes 2, 2,... Is maintained in a negative pressure state by the vacuum suction pump P5 while traveling.
The slurry is supplied from the slurry supply device 12 onto the filter cloth 1.

The slurry on the filter cloth 1 is drained through the filter cloth 1 while being transported with the travel of the filter cloth 1 by maintaining the inside of the vacuum boxes 2, 2. Becomes

At this time, the cleaning liquid supply devices 13, 13
A washing liquid (for example, water) is supplied from the washing machine to perform cake washing. The vacuum boxes 2, 2,... Are integrated with the filter cloth 1 by vacuum pressure during vacuum suction, and move in the same direction and at the same speed as the filter cloth 1 by the extension operation of the air cylinder 6.
If the vacuum boxes 2, 2 ... have moved a certain distance, the valve B
1, B2, B3 are opened, and valves B4, B5,
B6 is closed and the vacuum chambers 2, 2,... Are returned to atmospheric pressure. At this time, the vacuum boxes 2 and 2
... is quickly returned to the original position. Thereafter, the reciprocating operation of the vacuum boxes 2, 2,... Is repeatedly performed.

Into the vacuum boxes 2, 2,..., The liquid in the slurry (and the cake C1) and the cake washing liquid are sucked and introduced. These liquid components and the cake washing liquid are stored in a storage tank T
After being temporarily stored in T1 and T2, it is discharged by a liquid discharge pump. However, in the apparatus of this example, so-called countercurrent cleaning is performed. That is, first, the filter cloth cleaning device 40
The washing liquid used for washing the filter cloth 1 is supplied to the cake washing liquid supply device 13b on the rear side by the secondary washing liquid circulation pump P4.
It is used for recycling. Subsequently, the washing liquid from the cake washing liquid supply device 13b on the rear side is sucked into the vacuum boxes 2, 2,... On the terminal side of the vacuum boxes 2, 2,. , Primary cleaning liquid circulation pump P
3 circulates and supplies the cleaning liquid to the front side cleaning liquid supply device 13a.

The cake C2, which has passed through the reciprocating operation range of the vacuum boxes 2, 2... By the movement of the filter cloth 1, is pressurized by a pair of pressing rolls 3, 4 and further filtered. That is,
2 and 3, cake C after vacuum filtration
2 is sandwiched between the filter cloth 1 and the upper pressing roll 3,
It is transferred while being squeezed from the part (a) to the part (c).
From the part (a) to the part (b), a surface pressure corresponding to the tension of the filter cloth 1 is applied to the cake C2 toward the center of the upper pressing roll 3, and the squeezing and dewatering of the cake C2 gradually progresses. I do.

Subsequently, in part (b), the cylinder 1
The lower pressing roll 4 is pressed against the upper pressing roll 3 by the contraction of the piston rods 19a, 19a. For this reason, the cake C2 dewatered to a certain extent in the part (a) to the part (b) is pressed between the upper pressing roll 3 and the filter cloth 1 pressed by the lower pressing roll 4 toward the upper pressing roll 3. It is drained.

It should be noted that the filter cloth 1 is pressed by the lower pressing roll 4 in the direction of the pressing roll 3.
That is, the traveling of the filter cloth 1 accompanying the rotational drive of the pressing roll 3 is ensured. Therefore, in the present device, the more the drainage property by pressing is increased, the less the filter cloth 1 slips. Further, in this apparatus, since both the upper and lower pressing rolls 3 and 4 rotate with the travel of the filter cloth 1, even if the pressing force of the lower pressing roll 4 in the direction of the pressing roll 3 is increased, the filter cloth is not removed. 1 does not substantially increase the tension. Therefore, in the present apparatus, it is not necessary to consider the breaking of the filter cloth 1 and the pressing pressure, that is, the lower pressing roll 4
, The pressing force in the direction of the pressing roll 3 can be increased.

Now, the cake C3 after passing through the portion (c) is
For the amount attached to the upper pressing roll 3, the scraper S
1 is scraped off onto the filter cloth 1 and discharged together with the remaining cake on the filter cloth 1 by the scraper S2. C4
Indicates a discharged cake.

After the cake is discharged, the filter cloth 1 is returned again below the slurry supply device 12 by the return rolls 5C and 5D. At this time, the filter cloth 1 is cleaned in the filter cloth cleaning apparatus 40.

In the apparatus of the present embodiment, the filter cloth 1 is moved by the lower pressing roll 4 to the upper pressing roll 3 especially in the initial operation.
, It is assumed that the starting end of the vacuum-filtered cake C2 cannot pass through the pressed portion (that is, the portion (b)). In this case, cake is deposited on the portion (that is, portion (a) to portion (b)) reaching the pressed portion, and the operation cannot be continued. In such a case, if the pressing pressure by the lower pressing roll 4 is reduced,
Although it is possible for the cake C2 to pass through the pressed portion, not only the dewatering property is reduced, but also the filter cloth 1 is likely to slip.

In order to solve such a problem, the apparatus according to the present embodiment is provided with side end pressing rolls 30 for bringing both ends of the filter cloth 1 into press contact with the upper pressing roll 3. That is,
As shown in FIGS. 4 and 5, in the initial stage of operation, the piston rods 19a of the cylinders 19, 19 are extended to raise the side end pressing rolls 30, 30, thereby raising both side ends of the filter cloth 1 upward. It is pressed against the pressing roll 3. In this case, since the lower pressing roll 4 is separated from the upper pressing roll 3 by the extension operation of the cylinders 19, 19, the dewatering by the lower pressing roll 4 is not performed. Accordingly, both ends of the filter cloth 1 are reliably pressed against the upper pressing roll 3, and the transfer and dewatering of the cake C <b> 2 are performed in the center of the filter cloth 1. As a result, no slippage of the filter cloth 1 occurs in the early stage of operation.

This state is maintained at least until the starting end of the cake C2 has passed the portion of the lower squeeze roll 4 against which the filter cloth 1 is pressed. Then, when the starting end of the cake 2 has passed through the pressing portion, the piston rods 19a, 19a of the cylinders 19, 19 are contracted to separate the side end pressing rolls 30, 30 from the upper pressing roll 3, and the lower side. The pressing roll 4 is pressed against the upper pressing roll 3 to start pressing the cake C2. This cylinder 19,
The switching timing of expansion and contraction of 19 is determined, for example, by a timer or the like, for example, the timing of pressing the filter cloth 1 by the lower pressing roll 4 of the cake C2 described above,
It can be done automatically or artificially.

<Other Examples> Within the scope of the present invention, the side end pressing rolls 30, 30 or the lower pressing rolls 4 may be provided at a position different from the above-mentioned example, or a plurality of them may be provided. For example, in the above example, the side end pressing rolls are arranged side by side with the lower pressing rolls on the tip end side from the fulcrum of the lever, the driving assistance of the filter cloth by the side end pressing rolls, and the pressing dehydration by the lower pressing rolls. Can be performed simultaneously.

In the above example, both the lower pressing roll 4 and the side end pressing rolls 30, 30 are provided for one lever, but a lever dedicated to each roll may be provided. In this case, the lower pressing roll and the side end pressing roll can be operated separately, for example,
The driving assistance of the filter cloth by the side end pressing roll and the pressing dewatering by the lower pressing roll can be performed simultaneously or without interruption.

In the above example, the upper pressing roll 3 is driven to drive the filter cloth. However, both the upper pressing roll and the lower pressing roll, or only the lower pressing roll, may be driven. it can.

Further, the upper pressing roll 3 in the above example was used.
Is movable in the direction of the lower pressing roll 4 and is configured to be pressed against the lower pressing roll 4 by its own weight or by a separately provided pressing means, or the upper pressing roll 3 and the lower pressing roll 4 in the above example. Can be arranged upside down.

On the other hand, the above-mentioned example is a vacuum filter of a type in which the vacuum boxes 2, 2... Reciprocate, but the present invention is not limited to this. It is also possible to use it for a vacuum filter of a type that keeps a vacuum.

[0052]

As described above, according to the present invention, an inexpensive vacuum filter which can stably and continuously perform filtration and has a high liquid removing property can be obtained.

[Brief description of the drawings]

FIG. 1 is a flow sheet of a vacuum filter according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the vacuum filter according to the present invention.

FIG. 3 is a diagram showing a main part as viewed in the direction of arrows II.

FIG. 4 is an enlarged sectional view of a main part of the vacuum filter according to the present invention.

FIG. 5 is a diagram showing a main part as viewed in the direction of arrows II-II.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Filter cloth, 2 ... Vacuum box, 3 ... Upper pressing roll, 4 ... Lower pressing roll, 5A-5D ... Return roll, 6 ... Cylinder, 7 ... Rail, 12 ... Slurry supply device, 13 ... Cake washing liquid supply device , 14: guide roll, 16: lever, 18: pin, 19: cylinder, 30: side end pressing roll, B1 to B6: valve, T1 to T3: storage tank,
P1, P2: liquid discharge pump, P3: primary cleaning liquid circulation pump, P4: secondary cleaning liquid circulation pump, P5: vacuum suction pump.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Ashigaya 2-17-15 Tsukushima, Chuo-ku, Tokyo Tsukishima Machinery Co., Ltd. (72) Inventor Kazuhiro Nose 2-17-15 Tsukushima, Chuo-ku, Tokyo Tsukishima Machinery Co., Ltd.

Claims (6)

[Claims] 1. A vacuum filter comprising a filter cloth and a vacuum box, wherein the filter cloth supplied with slurry on its upper surface is run in a state of being in contact with the vacuum box to filter the slurry. In the machine, between a position where the filter cloth and the vacuum box are separated from each other and a position where a cake generated by the filtration is discharged from the filter cloth, a pair of upper and lower sides sandwiching the filter cloth are provided. And a pressurizing means for pressurizing at least one of the pair of squeezing rolls toward the other squeezing roll opposed thereto. 2. A squeezing roll on the upper side of the filter cloth,
2. A vacuum filter according to claim 1, further comprising means for bringing both ends of said filter cloth into pressure contact with each other. 3. The vacuum filter according to claim 1, further comprising driving means for rotating at least one of the pair of pressing rolls. 4. A filtering method using a vacuum filter according to claim 2, wherein at least until a starting end of the cake passes through a pressing position by the pair of pressing rolls, A filtering method, wherein both ends of the filter cloth are brought into pressure contact with a pressing roll. 5. The filtering method using a vacuum filter according to claim 2, wherein the cake is squeezed by the pair of squeezing rolls until the starting end of the cake passes through a squeezing position by the pair of squeezing rolls. Without contacting the pressing rolls on the upper surface side of the filter cloth with both ends of the filter cloth under pressure, if the starting end of the cake has passed through the pressing position by the pair of pressing rolls, the filter A filtration method, comprising releasing pressure contact between both ends of the filter cloth with a compression roll on the upper surface side of the cloth, and starting compression by the pair of compression rolls. 6. The vacuum filter according to claim 4, wherein at least one of the pair of squeezing rolls is rotated to move the filter cloth.