JP5011409B2 - Environmentally friendly solid-liquid separation system - Google Patents

Description

The present invention relates to an environment-friendly solid-liquid separation system that reduces the generation of CO ₂ .

Conventionally, for example, in a wafer manufacturing process, a lump of silicon single crystal (ingot) as a material of a wafer has a diameter of 300 mm and a length of 2 m in the case of 12 inches, for example. In order to slice this ingot to a thickness of about 1 mm, first, both ends are removed in a flat shape, and the outer periphery is ground and processed into a cylindrical shape to adjust the shape. And after processing the V-groove-shaped notch used as a surface orientation mark in the outer periphery of a cylindrical raw material, the wafer raw material is simultaneously sliced with a wire saw. The coolant liquid used at this time is mixed with, for example, fine powder of silicon carbide (SiC) which has high hardness and durability and exhibits an effect as an abrasive. As a result, the abrasive attached to the wire of the wire saw cuts the ingot into slices.
The spent coolant liquid used for wafer slicing and peripheral grinding of the ingot, which is the pre-processing, is purified and drained into the river, and part of it is filtered and reused. (For example, refer to Patent Document 1).

Japanese Patent No. 3199159 (paragraphs 0013 to 20, FIG. 1)

However, many electric pumps are used in such a coolant liquid reuse system, and motors that drive many pumps are connected.
In Japanese power situation, because electricity 60% thermal power, 30% nuclear, where 10% is made of hydro, using power 1 kwh, resulting in generating the CO ₂ of 0.36 kg. For this reason, in a system using many electric motors, there is a problem that CO ₂ is indirectly generated to cause an environmental problem.

  FIG. 2 is a configuration diagram showing a conventional solid-liquid separation system that purifies part of the drainage and drains it into a river. In a conventional solid-liquid separation system 101, a stock solution is supplied from a stock solution tank 1 to a centrifuge 12, where solids and liquids are separated, and the separated liquid separation solution is subjected to membrane filtration via a feed pipe 22. Supplied to the device 13. In the membrane filtration device 13, the filtrate obtained by removing fine particles from the solid matter in the separated liquid is stored in the filtrate tank 4. Further, this filtrate is supplied as a regenerated coolant liquid to the production line 5 through the feed pipe 26 by the second electric pump (M2 + P2) of the filtrate tank 4. The coolant liquid reused in the production line 5 becomes a used liquid and is sent to the third electric pump (M3 + P3) through the recovery pipe 27 and returned to the stock solution tank 1 through the recovery pipe 28. The returned spent solution is called a stock solution.

  On the other hand, the staying liquid in the solid content receiving tray 12 a of the centrifuge 12 is recovered to the concentrate tank 6 by the recovery pipe 23. In addition, the concentrated liquid that has exited from the membrane filtration device 13 is also recovered into the concentrated liquid tank 6 through the recovery pipe 25. In order to enhance sedimentation of the sediment, for example, sodium hypochlorite or a polymer flocculant (polyaluminum chloride, PAC, etc.) flocculant 6a is added to the concentrate tank 6 through the feed pipe 31. . The separated liquid in the upper layer portion of the concentrate tank 6 is supplied to the thickener 8 which is a contaminated water treatment apparatus via the supply pipe 32 by the fifth electric pump (M5 + P5). The upper layer of the thickener 8 is fed to the PH treatment tank 11 by the seventh electric pump (M7 + P7) through the feed pipe 34, and after adjusting the pH, the activated carbon filter, ion exchange resin device, UV sterilization (not shown) is used. It is drained into sewage or general river by a ninth electric pump (M9 + P9) through a machine.

  The sediment in the lower layer of the other concentrate tank 6 is fed to the filter press device 9 through the feed pipe 33 by the sixth electric pump (M6 + P6). The sediment in the lower layer portion of the thickener 8 is also fed to the filter press device 9 via the feed pipe 36 by the eighth electric pump (M8 + P8). The filter press device 9 presses these sediments, and the solid matter is disposed of by an industrial waste disposal company.

That is, these first to third electric pumps are connected to electric motors (hereinafter referred to as motors) M1 to M3 that drive pumps P1 to P3, and the fifth to ninth electric pumps are connected to pumps P5 to P9. Motors M5 to M9 to be driven are connected. As a result, the annual CO ₂ generation amount can be calculated from the operating time of these motors M1 to M3 and M5 to M9.
In a factory that manufactures wafers, full operation (three shift work) is common because of expensive equipment machines, so the daily operation time is 22 hours and the monthly operation day is 24 days.
The outputs of the motors M1 to M3 and M5 to M9 are 3.7 kW for the motor M1 to M3, 3.7 kW for the motor M5, 5.5 kW for the motor M6, and 3.7 kW for the motor M7 to M9. The total is 33.2 kw.
Therefore, the amount of CO ₂ generated per unit time is added to the annual operating hours.
33.2 kw × 22h × 24 days × December × 0.36 kg / h = 75.7 tons.

Thus, in the conventional solid-liquid separation system 101, since the number of pumps P1 to P3 and P5 to P9 is large, the power consumption of the motors M1 to M3 and M5 to M9 is also large. There was a problem of generating ₂ .

Accordingly, an object of the present invention is to provide an environment-compatible solid-liquid separation system that reduces the amount of power used and suppresses the generation of CO _{2 to} prevent global warming.

  The environment-friendly solid-liquid separation system (100) according to claim 1 recovers the coolant liquid used in the production line (5), separates the solid-liquid, filters and reuses it. The solid-liquid separation system (100) of the present invention includes a stock solution tank (1) for collecting the coolant used in the production line (5), and a first electric pump for feeding the stock solution from the stock solution tank (1) ( M1 + P1), a centrifuge (2) in which the stock solution is fed from the first electric pump (M1 + P1) through a feed pipe (21), and the solids and separated liquid of the stock solution by the centrifuge (2) And the separation liquid is separated into a filtrate and a concentrated liquid by the membrane filtration device (3) to which the separation liquid is fed by a feeding pipe (22) and the membrane filtration device (3), Filtrate is fed through the feed pipe (24) and stored An excess liquid tank (4), a second electric pump (M2 + P2) for feeding the filtrate stored in the filtrate tank (4) to the production line (5), and the production line (5) A third electric pump (M3 + P3) that feeds the spent liquid of the coolant liquid to the raw liquid tank (1), and a concentrated liquid tank in which the concentrated liquid of the membrane filtration device (3) is recovered by a recovery path (25) (6) and a fourth electric pump (M4 + P4) provided in the concentrate tank (6), and a valve (7) provided in the feed pipe (21), and the fourth electric pump A feed pipe (30) is disposed between (M4 + P4) and the concentrate in the concentrate tank (6) is supplied to the centrifuge (2).

  The invention described in claim 2 is the environment-friendly solid-liquid separation system (100) according to claim 1, wherein the centrifuge (2) is a vertical centrifuge. And

According to the first aspect of the present invention, the concentrated liquid in the concentrated liquid tank 6 is supplied to the vertical centrifuge by switching the valve provided in the feed pipe, and the vertical centrifuge is separated. Since the concentrated liquid can be separated, the separated liquid after the recovery of the solid content becomes only the liquid, and it is recovered as a filtrate from the membrane filtration device into the filtrate tank, allowing the concentrated liquid to be reused. Become. In addition, since the concentrated liquid can be easily treated as described above, the conventional wastewater treatment facility can be dispensed with, and an environment-friendly solid-liquid separation system that can eliminate drainage into the river becomes possible. .
Thereby, since the number of motors and pumps used in the conventional wastewater treatment facility can be halved, an environment-friendly solid-liquid separation system with reduced electrical energy can be provided. As a result, the used coolant liquid can be circulated in the solid-liquid separation system and reused without being discharged to the river, so the surrounding environment is not polluted and power consumption is reduced. Therefore, it is possible to suppress the generation of CO ₂ which is a main cause of global warming as a global environmental problem.

  According to the second aspect of the present invention, the vertical centrifuge is more concentrated than the conventional horizontal centrifuge in that the stock solution enters from the top and falls down against gravity, and is centrifuged into a screw blade integral with the rotating shaft. Since force is applied, fine solids are evenly dispersed, and high recovery and low liquid content can be realized.

It is a block diagram which shows typically the environment corresponding type solid-liquid separation system of this invention. It is a block diagram which shows a conventional solid-liquid separation system typically.

An embodiment of a solid-liquid separation system for non-drainage according to the present invention will be described in detail with reference to the drawings. The coolant liquid refers to a cutting liquid including oil other than water.
As shown in FIG. 1, in the stock solution tank 1, a spent liquid of the coolant liquid supplied for cutting processing on the production line 5 is collected. The first electric pump (M1 + P1) of the stock solution tank 1 rotates the pump P1 by driving the motor M1, and supplies the stock solution to the vertical centrifuge 2 through the feed pipe 21. The stock solution supplied to the vertical centrifuge 2 is separated into a solid and a separated liquid, the solid is discharged to the lower solid receiving tray 2a, and the separated liquid is sent to the membrane filtration device 3 through the feed pipe 22. Be paid. In the membrane filtration device 3, the filtrate and the concentrate are separated, and the filtrate is collected and stored in the filtrate tank 4 through the feed pipe 24, and the concentrate is collected into the concentrate tank 6 through the feed pipe 25. Stored. Further, this filtrate is repeatedly supplied to the production line 5 via the feed pipe 26 by the second electric pump (M2 + P2) of the filtrate tank 4.

The stock solution tank 1 is a tank that collects the used coolant liquid used in the production line 5. The stock solution tank 1 may be disposed in a pit provided in the basement, or may be disposed on the ground floor.
When the used solution from the production line 5 enters the stock solution tank 1, the used solution becomes the stock solution.
A first electric pump (M1 + P1) is set on the upper part of the stock solution tank 1. The stock solution is supplied to the top of the vertical centrifuge 3 by a feed pipe 21 connected to the pump P1. In addition, a valve (three-way electromagnetic valve) 7 is disposed in the feed pipe 21.

The centrifuge 2 is a vertical type, and the stock solution is fed from the stock solution tank 1 to the top of the vertical centrifuge 2. As shown in FIG. 2, the vertical centrifuge 2 is more resistant to gravity than the conventional horizontal centrifuge 2 and can use centrifugal force, so that solids are evenly dispersed and high recovery rate is achieved. Low liquid content can be realized.
In ordinary stock solution processing (referred to as primary processing), solids up to a particle size (1 to 10 μ) can be recovered. However, a solid content having a smaller particle diameter (0.1 to 1 μ) flows to the membrane filtration device 3 together with the separation liquid, and the particles separated by the membrane filtration device 3 become a concentrated solution and are concentrated through the collection tube 25. It is collected in the liquid tank 6.

Therefore, the small particle size (0.1 to 1 μ) of the concentrated liquid can be separated by changing the separation condition time of the vertical centrifuge 2 and performing re-separation (referred to as secondary treatment).
With this separation condition, it is only necessary to fix the centrifugal effect of the vertical centrifuge 2 and the size of the weir plate without changing them and increase the centrifugation time.
For example, in the first treatment, if the solid content having a particle size (1 to 10 μ) can be separated by the centrifugal effect of 10 seconds, the solid content having a smaller particle size (0.1 to 1 μ) is Since it is proportional to the square of the particle size ratio, 10 seconds × 10 ² = 1000 seconds (≈16.7 minutes). In other words, the secondary processing may be performed by supplying the internal residence volume, for example, for 17 minutes.

Therefore, in the case of the secondary treatment, the supply of the stock solution of the primary treatment is stopped, the concentrate in the concentrate tank 6 is supplied to the vertical centrifuge 2, and the centrifuge time is operated, for example, for 17 minutes to reduce the particle size. Collect (0.1-1 μ) solids.
In general, the concentration limit of the membrane filtration device 3 is about 0.5% (5000 PPM), and if the SS component of the suspended solid amount in the separated water of the vertical centrifuge 2 is 500 PPM, the concentration is 10 times. If it is 100PPM, it will be 50 times concentrated and the amount of concentrate will be determined. If the primary treatment and the secondary treatment are balanced and the type and number of the vertical centrifuges 2 are determined, sufficient effects can be exhibited.
As a result, since the separated liquid after the recovery of the solid content is only the liquid content, a circulation cycle in which it is recovered from the membrane filtration device 3 as the filtrate into the filtrate tank 4 and reused becomes possible.
Thus, since processing of a concentrate can be performed easily, all the waste water treatment facilities can be made unnecessary.

The membrane filtration device 3 is a device using a ceramic membrane filter. In the membrane filtration device 3, the filtrate is further separated into a filtrate from which fine particles have been removed and the remaining liquid concentrate, and the filtrate is recovered to the filtrate tank 4 by the feed pipe 24, and the concentrate is fed from the feed pipe. 25 to be collected into the concentrate tank 6.
The ceramic membrane is microfiltration with a porous ceramic membrane with a pore size of 0.1μ, and it has higher mechanical strength than polymer membranes such as hollow fiber membranes, and there is no membrane breakage, so it can supply safe water, Excellent durability and low running cost.
Here, an excellent filtering ability of 0.1 to 1 micron is exhibited. Thereby, the filtration of the stable separated liquid can be performed. Furthermore, since the environment-compatible solid-liquid separation system 100 has a simple configuration, it can be easily operated and maintained, and further, membrane filtration can be performed without injecting a flocculant, and operation management is easy. In addition, the environment-compatible solid-liquid separation system 100 has fewer pumps and the like than the conventional solid-liquid separation system 101 described above, so that the apparatus can be made compact, space-saving and processing capacity can be increased.

  The filtrate tank 4 is a tank in which the filtrate filtered by the membrane filtration device 3 is stored by the recovery path 24.

The production line 5 includes a step of removing both ends of a silicon single crystal lump (ingot) in a flat shape, a step of grinding the outer periphery into a cylindrical shape to adjust the shape, and a surface orientation mark on the cylindrical outer periphery. A plurality of machine tool groups used in a step of processing a V-groove shaped notch, a step of slicing to a predetermined thickness by a wire saw, and the like.
Moreover, the used liquid of the production line 5 is returned to the stock solution tank 1 by the third electric pump M3 + P3 through the recovery path 28 to become the stock solution.
The production line 5 may be a single machine that uses a coolant liquid.

Moreover, although the manufacturing line 5 demonstrated in the wafer manufacturing process, you may be a manufacturing line of the manufacturing process by the atomizing method which manufactures metal powder, such as a rare metal.
The atomizing method is a method for producing metal powder by instantaneously pulverizing and rapidly solidifying molten metal using high-pressure water, and is characterized in that the component, shape, density, particle size, etc. of the powder can be freely controlled. Environmentally friendly solid-liquid separation system 100 of the present invention can be employed for the high pressure water source used in the manufacturing process by the atomizing method. Also, other production lines may be used.

The concentrated liquid tank 6 is a tank in which the concentrated liquid of the membrane filtration device 3 is recovered by the recovery path 25. A fourth electric pump (M4 + P4) is disposed on the concentrate tank 6, and the concentrate is fed to the three-way electromagnetic valve 7 of the feed pipe 21 by this pump P4. By providing a dedicated time for separating the concentrate in the concentrate tank 6, it is possible to filter the concentrate in the secondary treatment.
The staying liquid stored in the separated solids receiver 2 a in the vertical centrifuge 2 is collected in the stock solution tank 1 through the collection path 29.

The valve 7 is preferably a three-way solenoid valve here, but may be another type of valve. The valve 7 is a switching valve that cuts off and switches the flow of the stock solution from the stock solution tank 1 when performing a secondary process for treating the concentrate in the concentrate tank 6. These three-way solenoid valve 7, motors M1 to M4, vertical centrifugal separator 2, membrane filtration device 3 and the like are electrically connected to a control device (not shown) and controlled by the control device. Secondary processing is also automatically controlled by the control program. Further, the extension of the separation time is determined according to the concentration of the material.
In this secondary process, the operating time of the vertical centrifuge 2 is changed, and the solid content in the concentrate can be removed by the secondary process for an appropriate time, and the regenerated coolant liquid can be taken out.
As a result, the environment-compatible solid-liquid separation system 100 does not require drainage treatment facilities, and is a non-drainage and drainage system that does not flow outside the factory such as rivers and sewage.

In addition, since solid content can be removed by the secondary treatment by the vertical centrifuge 2, the reliability of the system can be improved by arranging the membrane filtration device 3 later. Since the concentrate discharged from the membrane filtration device 3 becomes a filtrate as a result, an increase in the concentration of the coolant liquid can be suppressed and the life of the coolant liquid can be extended.
That is, since the concentration is shortened average distance between particles and increases, decreases the electrostatic repulsion effect by the steric hindrance effect, likely to aggregate. Therefore, the concentrated liquid is taken out by the membrane filtration device 3 in the system, and a state in which the concentrated liquid is easily aggregated is created, which is advantageous for the secondary treatment. Therefore, the combination of the vertical centrifuge 2 and the membrane filtration device 3 can improve the reliability of the system and solve the problem of purification of the coolant.

Here, the amount of electric power used by the environment-compatible solid-liquid separation system 100 of the present invention is totaled, the amount of CO ₂ generated is calculated, the difference from the conventional amount generated is obtained, and the effect is confirmed.
In the first to fourth electric pumps, motors M1 to M4 are arranged to drive the pumps P1 to P4. The amount of CO2 generated annually is calculated from the operating time of these motors.
The operating conditions are the same.
The output of each motor is
The sum of the motors M1 to M3: 3.7 kw and the motor M4: 5.5 kw is 16.6 kw. 16.6kw × 22h × 24 days × December × 0.36kg = 37.8 tons.

このように、従来の固液分離システム１０１では、年間７５．７ｔｏｎのＣＯ_２を発生させているのに対し、本発明のシステムでは、ちょうど５０％の電力の消費を抑え、３７．９tonのＣＯ_２の発生を削減した効果を奏する環境対応型の無排水固液分離システムを提供することができる。 [Comparison table]

As described above, the conventional solid-liquid separation system 101 generates 75.7 ton of CO ₂ per year, whereas the system of the present invention suppresses power consumption of just 50%, and 37.9 ton of CO 2. _Thus, it is possible to provide an environment-friendly undrained solid-liquid separation system that has the effect of reducing the occurrence of ₂ .

The coolant solution is supplied to the production line 5 and is exposed to the atmosphere until it returns to the stock solution tank 1 and evaporates a considerable amount. Therefore, the supply pipe 26 just before the production line 5 is supplied with the replenisher solution. There is a water supply port. From this water supply port, you may supply the pure water manufactured via the dehydration processing apparatus which is not illustrated, for example.
Further, in the conventional solid-liquid separation system 101, a separation liquid tank 10 (not shown) is disposed between the centrifuge 12 and the membrane filtration device 13, and a tenth electric pump (M10 + P10) is disposed on the separation liquid tank 10. ) Is arranged. Similarly, the environment-friendly solid-liquid separation system 100 of the present invention is also disposed between the centrifuge 2 and the membrane filtration device 3, but both are not shown.

  As mentioned above, although embodiment of this invention was described, it can change suitably and can implement without being limited to this embodiment. For example, the types of the pumps P1 to P4 may be changed to those with low power consumption. Moreover, you may install two or more centrifuges 2 and the membrane filtration apparatus 3 according to the usage-amount of the coolant liquid in the manufacturing line.

1 Stock solution tank 2 Centrifuge (vertical centrifuge)
2a Solid material tray 3 Membrane filtration device 4 Filtrate tank 5 Production line 6 Concentrate tank 7 Valve (3-way solenoid valve)
21, 22, 24, 26 Supply pipe 25, 27, 28, 29 Recovery pipe M1 + P1 1st electric pump M2 + P2 2nd electric pump M3 + P3 3rd electric pump M4 + P4 4th electric pump M1 1st motor M2 2nd motor M3 3rd Motor M4 Fourth motor P1, P2, P3, P4 Pump 100 Solid-liquid separation system (environmentally friendly solid-liquid separation system)

Claims (2)

An environmentally friendly solid-liquid separation system (100) that collects the coolant liquid used in the production line (5), separates the solid liquid, and filters and reuses it.
A stock solution tank (1) for recovering the coolant used in the production line (5);
A first electric pump (M1 + P1) for feeding the stock solution from the stock solution tank (1);
A centrifuge (2) to which the stock solution is fed from the first electric pump (M1 + P1) through a feed pipe (21);
A membrane filtration device (3) separated by the centrifuge (2) into a solid and a separated solution of the stock solution, and the separated solution is fed by a feed pipe (22);
After separating the separated liquid into a filtrate and a concentrated liquid by the membrane filtration device (3), a filtrate tank (4) in which the filtrate is fed and stored by a feeding pipe (24);
A second electric pump (M2 + P2) for feeding the filtrate stored in the filtrate tank (4) to the production line (5);
A third electric pump (M3 + P3) that feeds the spent liquid of the coolant liquid from the production line (5) to the stock solution tank (1);
A concentrate tank (6) in which the concentrate of the membrane filtration device (3) is recovered by a recovery path (25);
A fourth electric pump (M4 + P4) provided in the concentrate tank (6),
A feeding pipe (30) is disposed between the valve (7) provided in the feeding pipe (21) and the fourth electric pump (M4 + P4), and the concentrated liquid in the concentrated liquid tank (6) is supplied. An environmentally-friendly solid-liquid separation system (100), characterized in that it is supplied to the centrifuge (2).   The environment-friendly solid-liquid separation system (100) according to claim 1, wherein the centrifuge (2) is a vertical centrifuge.

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