JP2631082B2 - Electrostatic treatment apparatus and method for treating alkaline cleaning liquid in degreasing process using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic processing apparatus capable of efficiently processing an alkaline cleaning liquid and the like and a cleaning liquid processing system capable of completely circulating a water-soluble processing liquid in ultra-precision processing or the like.

[0002]

2. Description of the Related Art An alkaline cleaning liquid is used for cleaning and removing oils and metal powder adhering to a workpiece (work) such as grinding, cutting, and pressing. A detergent whose emulsifying property is one aspect of the cleaning effect. Therefore, contaminants such as oil and sludge washed off from the processed product are emulsified and present in the cleaning liquid, and it is very difficult to regenerate the contaminated cleaning liquid. Conventionally, as a method of treating the cleaning liquid, only an oil layer formed on the liquid surface of the cleaning liquid that has reached the contamination limit is removed. In such a method, the surfactant present at the interface is removed together with the oil component. Therefore, 50% or more of the surfactant that is not originally consumed is discarded in an unused state, which is very uneconomical. In addition, the alkaline cleaning liquid from which the oil layer has been removed in this manner,
The emulsion contains a considerable amount of oil and sludge, and more than 50% of the surfactant has disappeared, so the detergency has decreased and it cannot be reused efficiently. .

[0003]

The present inventor has developed a series of electrostatic filtration devices utilizing an electrostatic field in an electrically insulating solvent as an effective device for treating contaminated water or the like by a solvent. (Japanese Patent Publication No. 40-15549, Japanese Patent Publication No. 51-3941,
JP-B-51-3942, JP-B-51-23742, JP-B
It is known that these apparatuses can efficiently separate and remove even a small amount of oil contained in the treated water with these apparatuses. Therefore, in the present invention, utilizing the principle of the above-mentioned electrostatic filtration device, as described above, the alkaline cleaning liquid is efficiently separated into oil and water without wasteful consumption of the surfactant during use, and is re-used. It is an object to provide a processing device that can be used.

[0004]

In the apparatus of the present invention, an inlet for a liquid to be treated is provided on the bottom surface, and a pair of electrodes are arranged in a solvent A in a tank containing an electrically insulating solvent A therein. A high-voltage direct-current voltage is applied between the electrodes, the side wall of the tank is double-walled, a pocket is formed between the inner side wall and the outer side wall, and a tank is formed on the inner side wall. The edge is located above the liquid level of the solvent A, and the floating impurities of the sludge layer formed on the upper surface of the solvent A overflow from the upper edge of the inner wall toward the pocket. ,
The pair of electrodes are biased to one side inside the tank and inclined upward at an angle of 25 to 40 ° with respect to a horizontal plane. The pocket is provided on the side wall of the tank where the upper edge of the electrode is located, and a blind straightening plate is provided to be inclined upward from the center of the tank toward the top of the pocket. The blind rectifying plate covers the upper ends of the pair of electrodes and has an upper end located between the inner side wall and the outer side wall. In addition, a porous baffle is substantially above the blind baffle above the blind baffle so as to cover an opening formed between the upper end of the baffle and the outer wall. The floating sludge separation chamber is provided horizontally, and a floating sludge separation chamber having an open bottom is provided above the porous flow straightening plate. In addition, the drainage port of the treated water is provided on the wall surface facing the pocket of the tank so as to be located above the lower end of the inner wall of the floating sludge separation chamber, and the drainage port provided on the bottom of the tank A water conditioner is provided at the inlet of the liquid to be treated. Further, the solvent outlet is provided on the wall surface facing the pocket of the tank, above the upper end of the electrode, and below the lower end of the blind straightening plate, and the solvent inlet is provided. , Near the bottom surface of the wall facing the pocket of the tank.

[0005] In the floating sludge separation chamber, a pipe for supplying cleaning water which is opened upward is provided on the inner peripheral portion thereof so that the floating sludge is transported upward surely. Preferably, a directed water flow is produced. In addition, it is preferable that the outer wall of the sludge separation chamber is formed in a double structure above the pipe so that floating sludge is removed by overflow.

In the apparatus of the present invention, the solvent used for the solvent layer includes: a. Not flammable or explosive b. Has a dielectric constant of 2.0 to 7.0 (20 ° C.) c. Specific gravity is 1.30 (20 ° C.) or more d. Has a KB value (a measure of the solubility of Kauri resin) of 90 or more e. It is preferable to use a material having a condition that the melting point is 0 ° C. or less, apply a high negative DC voltage to the cathode, and apply about 40 to 60 KV between the electrodes (in this case, The anode is on the ground side).

In the apparatus of the present invention as described above, Japanese Patent Publication No.
The liquid to be treated introduced from the bottom of the tank flies back and forth between the electrodes under the action of the electrostatic field, similarly to the apparatus described in JP-A-23742 and JP-B-5-83306. The oil contained in the liquid to be treated is dissolved in the solvent, the solid matter and other impurities are separated from the water, and rises linearly with the water from between the electrodes. Is present, the separated impurities, ie, sludge and moisture, are guided along the blind baffle plate above the pocket. Sludge that overflows from the inner wall into the pocket and flows down is removed from the drain provided at the bottom of the pocket, and the sludge that floats upward rises from the tip of the blind straightening vane and rises above the floating sludge separation chamber. Will be introduced.

[0008] Therefore, from the treated water drain port located at the upper end of the wall surface facing the pocket, the water (ie, the regenerating washing liquid) from which oil and sludge have been substantially removed contains the active ingredient dissolved in the water. Is efficiently taken out in a state where it is securely held, and the regenerated cleaning solution can be supplied to the degreasing step again for use.

The solvent discharged from the solvent outlet provided near the upper end of the solvent layer on the wall surface facing the pocket of the tank contains oil dissolved in the solvent. The solvent is separated and regenerated from the oil component by distillation or the like, and the regenerated solvent can be introduced again into the tank through a solvent inlet provided on the lower wall surface of the tank and used.

Therefore, in the present invention, the contaminated liquid of the alkaline cleaning liquid discharged from the degreasing tank is introduced into the tank from the liquid to be treated introduction port, and after the electrostatic treatment, the contaminated liquid discharged from the solvent discharge port is contaminated. The solvent is purified through a solvent regeneration tank, and the purified solvent is again introduced into the tank from the solvent inlet,
In addition, the regenerated cleaning liquid discharged from the treated water drain port is passed through a degreasing liquid supply adjusting device, and is again introduced into the degreasing tank as a part of the alkaline cleaning liquid, so that the solvent and the cleaning liquid are completely circulated in a closed system. It becomes possible.

[0011] In such a closed system, even a solvent such as tetrachloroethylene can be used with confidence, so that the oil content can be reliably removed from the liquid to be treated.
In addition, water-soluble components such as surfactants can be reused while being almost completely held in water.

[0012]

FIG. 1 shows an example of the apparatus according to the present invention. In this example, the contaminated liquid of the degreasing step is sent to the tank X by a pump,
From here, the liquid to be treated 2 is led to the inlet 3 on the bottom of the tank 1. An electrically insulating solvent A is housed in the tank 1, and a pair of electrodes 4 are arranged in the solvent A, and a high-voltage DC voltage is applied between the electrodes 4. The electrode 4 is biased to one side of the tank 1 and is inclined upward at an angle of about 30 ° with respect to a horizontal plane, and the tank side wall on the side where the upper edge of the electrode 4 exists is a double wall. A pocket 7 is formed between the inner wall 5 and the outer wall 6. A blind straightening plate 8 is provided which is inclined upward from the center of the tank 1 toward the upper side of the pocket 7. Above the straightening plate 8, a portion between the upper end of the straightening plate 8 and the outer wall 6 is provided. So as to cover the opening 9 of
A porous flow straightening plate 10 is provided substantially horizontally, and a floating sludge separation chamber 11 having an open bottom is provided thereon. On the inner periphery of the floating sludge separation chamber 11,
A washing water supply pipe 18 is provided which is opened upward. Further, above the pipe 18, the outer wall 19 of the floating sludge separation chamber 11 is formed in a double structure, and the floating sludge overflows. (Fig. 3
reference). Further, the drainage port 12 of the treated water is provided on the wall 13 facing the pocket 7 of the tank 1 in the floating sludge separation chamber 11.
A water conditioner 15 is attached to the liquid to be treated inlet 3 provided on the bottom surface of the tank 1. Further, the solvent discharge port 16 is provided on the wall surface 13 of the tank 1 facing the pocket 7.
The solvent inlet 17 is provided above the upper end of the electrode 4 and below the lower end of the blind straightening plate 8, and the solvent introduction port 17 is provided on the wall 13 facing the pocket 7 of the tank 1. Near the bottom of the
Is provided with a drain 20 for an intermediate layer.

Example 1 In order to confirm the treatment effect of the present invention, the following liquids A to C were subjected to electrostatic treatment using the apparatus shown in FIG. 1, and the pH and oil content of the liquid discharged from the drain port 12 were measured. , And those before treatment. A. Supernatant of the processing liquid in the initial stage of operation in a degreasing tank using an alkaline cleaning liquid containing the following components. B. Silicate 3500 ppm Phosphate 3500 ppm Carbonate 2000 ppm Caustic soda 7000 ppm Nonionic surfactant 1500 ppm A bottom solution of the processing solution of A. C. A treatment liquid when caustic soda is added to the treatment liquid of A and used for degreasing oily processed products. Table 1 shows the test results. However, the electrostatic treatment conditions are as follows. Applied voltage to electrostatic field: High negative DC voltage of 40 KV is applied to the cathode Amount of liquid flow from liquid inlet 3 to tank 1: continuous 400
ml-500ml / min

[0014]

[Table 1]

From the results shown in Table 1, even if a liquid containing a large amount of sludge or oil is discharged in the degreasing step, the apparatus of the present invention always uses a virgin liquid (stock solution of sample A) immediately after the start of use by electrostatic treatment. It can be seen that it can be regenerated into a liquid having the same composition as in the above), and therefore can be used as it is in circulation.

FIG. 2 shows an example of a closed system in which the apparatus shown in FIG. 1 is efficiently used by circulating an alkaline cleaning liquid in a degreasing step. Here, a contaminated alkaline cleaning liquid (degreasing liquid) sequentially discharged from a degreasing line including two degreasing tanks C is introduced into the tank 1 from the inlet 3 located on the bottom surface of the tank 1 as the liquid 2 to be treated. Then, the contaminated solvent discharged through the solvent outlet 16 is purified through the solvent regenerating tank B, and is again introduced into the tank 1 through the solvent inlet 17. Further, the regenerated cleaning liquid discharged from the treated water drain port 12 passes through the degreasing liquid supply adjusting device D, and is again introduced into the degreasing tank C as a part of the degreasing liquid. As is clear from Table 1, regardless of the degree of contamination of the liquid to be treated, the liquid exists as a stain-free liquid (containing no sludge or oil) similarly to the virgin liquid. Since it is contained in a state where substantially 100% remains, it can be efficiently circulated and used as a degreasing solution as it is. In this system, the contaminated degreasing solution discharged from the degreasing tank C is once introduced into the tank 1 through the contaminated liquid receiving tank X, and the contaminated solvent is passed through the solvent filter tank E to the contaminated solvent tank F. The solvent is guided to the solvent regenerating tank B, where it is distilled to regenerate the solvent. The solvent is regenerated from the solvent tank G to a solvent inlet 17 provided on the wall 13 of the tank 1. In such a system, in a closed system, the solvent and the alkaline cleaning liquid are efficiently circulated and used, so there is no danger of pollution or environmental pollution, and it is very economical, sanitary, and easy to work. . In such a system, a degreasing liquid having an oil concentration of, for example, about 2000 ppm to 5000 ppm is forcibly and continuously overflowed from a degreasing tank by a jetting method or the like, and is sent to a tank as a liquid to be treated. Can be made available for recycling.

According to the present invention, the results of trial calculations on the economics of using an alkaline cleaning solution electrostatically and circulating it in a closed system are shown below. From this, the system of the present invention shows that It can be seen that reliable processing can always be performed with an expense of 3% or less (ie, a method in which the cost is reduced by 97% or more compared to the conventional method).

Expenses required for the treatment of the present invention A) Estimation of running cost related to electrostatic treatment tank (1) Electricity consumed in relation to electrostatic field due to high DC voltage (40-60 KV): about 370 yen / day. (2) Loss of the solvent layer (tetrachloroethylene): Approximately 17 yen / day, with the natural vaporization loss plus the amount of the treatment liquid taken out being 10 ppm. (3) Electricity required for solvent distillation: about 118 yen / day at about 50 liters per day. B) Estimation of the running cost of the alkaline cleaning liquid Assuming that the simultaneous outflow from the sludge layer outlet of the electrostatic tank with the layer is about 3%, the amount of work taken out of the cleaning tank is about 2%.
%, For a total of 5%. The required cleaning solution per day is 10
Assuming 000kg, the price of cleaning solution is 1000 yen / kg
Taking a × 20 kg unit as an example, a practical use condition is 50,000 yen / day assuming that it is diluted 10 times. That is, the daily replenishment cost of the new solution is 50,000 yen / day. Expenses required for the treatment of the present invention (total of A and B) = about 50505 yen / day Expenses required for treatment by the conventional method a) Even if only the disposal cost of industrial waste is taken up, the disposal cost to the contractor is about Assuming 20,000 yen / drum, the cost is about 1,000,000 yen / day. b) If the 100% waste loss of the cleaning liquid is calculated, about 100
0000 yen / day. That is, the replenishment cost of the new solution is about 10
00000 yen / day. Expenses of the prior art (the sum of a and b) = about 2,000,000 yen / day present invention the ratio of about for expenses according to the conventional method costs by 50505 yen / about 2,000,000 yen = 2.53 / 100 = 2.53%

It is to be noted that the closed system of the present invention is characterized in that tetrachloroethylene designated as a second-class specific substance can be used without any danger under the law on the examination and production of chemical substances in Japan. However, as shown in FIG. 1, this is completely sealed with a water layer having a certain depth above the liquid surface of the solvent layer, and does not come into contact with the atmosphere. Since the regeneration of the solvent can be completely automated in a closed system through a distillation step, there is no danger of liquid leakage due to human error.

A rinsing step is provided after the degreasing step to remove residues from the surface of the processed product (work).
Sludge water discharged from the drain 20 of the pocket 7 of the Tekus treatment apparatus J equipped with a microfiltration and sterilization equipment
And can be used as rinsing water in a circulating manner.

Rinsing water is emulsion wastewater with a surfactant. If the contamination concentration of the degreasing solution increases in the preceding degreasing step, the oil content and the surfactant remaining in the processed product increase, and the rinsing water is used. However, in the present invention, the degreasing solution is circulated as described above,
Since the rinsing water can be kept fresh at all times, the concentration of the rinsing water is low and the rinsing water is in a stable state.

The treatment of the contaminated water is mainly to remove the surfactant, but the coagulation and precipitation system mainly comprising a chelating agent made of a unique aromatic polymer compound, wherein the surfactant is 0 and the oil content is 0.1. It has been confirmed that systemization as rinsing water for circulation is possible at 5 ppm or less.

[0023]

According to the apparatus of the present invention, a contaminant (oil, etc.) can be efficiently removed by a method that does not eliminate a surfactant such as an alkaline cleaning solution used in the degreasing step, and is very economical. It is possible to use an alkaline cleaning solution in a simple manner and without worrying about environmental pollution. That is, in the present invention, a unique electrostatic field is provided in the electrostatic liquid filter solvent by a direct current high voltage, and a strong electrostatic liquid to liquid extraction action is developed. In a state in which the main component and the active power are not consumed at all, the spoilage bacteria contained in the washing liquid are destroyed, and the oil is dissolved in the solvent layer, and the sludge is stable as a sludge layer formed on the upper surface of the solvent. And can be separated. In the present invention, by combining the treatment step of restoring the activity of the surfactant and the step of completely removing the residual activity of the surfactant and the like, the alkaline cleaning solution and the rinsing water are simultaneously and continuously treated in parallel. Further, by continuously circulating the solvent used as the electrostatic liquid filter, both the degreasing step and the rinsing step can be efficiently operated in a closed system.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the device of the present invention.

FIG. 2 is a system diagram for circulating and using an alkaline cleaning liquid in a degreasing step using the apparatus of FIG.

FIG. 3 is a sectional view of a main part of the apparatus of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tank 2 liquid to be treated 3 liquid inlet for treatment 4 electrode 5 inner wall 6 outer wall 7 pocket 8 blind straightening plate 9 opening 10 porous straightening plate 11 floating sludge separation chamber 12 drain port 13 wall surface 14 lower end of inner wall 15 Vessel 16 solvent outlet 17 solvent inlet 18 pipe 19 outer wall 20 drain

Claims (3)

(57) [Claims] An inlet 3 for a liquid 2 to be treated is provided on the bottom surface, and a pair of electrodes 4 are arranged in a solvent A of a tank 1 containing an electrically insulating solvent A therein. In an electrostatic processing apparatus to which a high-voltage DC voltage is applied, the side wall of the tank 1 is double-walled, and a pocket 7 is formed between the inner side wall 5 and the outer side wall 6. The edge is located above the liquid surface of the solvent A, and the slurry formed on the upper surface of the solvent A
In a device in which floating impurities of the luggage layer overflow from the upper edge of the inner wall 5 toward the pocket 7, the pair of electrodes 4 is biased to one side inside the tank 1, The pocket 7 is provided on the tank side wall on the side where the upper edge of the electrode 4 is present, and the pocket 7 is provided from the center of the tank 1. There is provided a blind rectifying plate 8 which is inclined upward toward the upper side of 7, the blind rectifying plate 8 covers the upper ends of the pair of electrodes 4, and is formed of the inner side wall 5 and the outer side wall 6. An upper end portion is provided therebetween; and a porous straightening plate is provided above the blind straightening plate 8 so as to cover the opening 9 between the upper end of the blind straightening plate 8 and the outer wall 6. Board 1
0 is provided substantially horizontally, a floating sludge separation chamber 11 having a downward opening is provided above the porous rectifying plate 10, and a drainage port 12 for treated water is provided in the tank 1. A water conditioner 15 is provided on the wall surface 13 facing the pocket 7 so as to be located above the lower end 14 of the inner wall of the floating sludge separation chamber 11. The solvent outlet 16 is provided so as to be located above the upper end of the electrode 4 and below the lower end of the blind straightening plate 8 on the wall surface 13 facing the pocket 7 of the tank 1. And a solvent inlet 17 is provided near the bottom surface of the wall 13 of the tank 1 facing the pocket 7, and a drain 20 is provided on the bottom surface of the pocket 7. Arca Electrostatic processing apparatus suitable for processing such system cleaning solution. 2. A pipe 18 for supplying washing water, which is opened upward, is provided on the inner peripheral portion of the floating sludge separation chamber 11, and further above the pipe 18, the floating sludge separation chamber 11 is provided. 2. The apparatus of claim 1 wherein the outer wall of the slab is formed in a double structure so that the floating sludge overflows. 3. An electrostatic filtration device according to claim 1 or 2, wherein the electrostatic filtration device is used in a degreasing step using an alkaline cleaning liquid, and the contaminated liquid of the alkaline cleaning liquid discharged from the degreasing tank is introduced into the liquid to be treated. After being introduced into the tank 1 through the port 3 and subjected to the electrostatic treatment, the contaminated solvent discharged from the solvent discharge port 16 is purified through the solvent regeneration tank B, and the purified solvent is returned to the tank 1 through the solvent inlet 17. And the regenerated cleaning liquid discharged from the treated water drain port 12 is introduced again into the degreasing tank C as a part of the alkaline cleaning liquid through the degreasing liquid supply adjusting device D, whereby the solvent and the cleaning liquid are closed. A method for treating an alkaline cleaning liquid in a degreasing step, wherein the alkaline cleaning liquid is used in circulation.