JP2009106802A - Pcb-containing oil sludge treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PCB-containing oil sludge treatment method which is suitable for detoxifying oil sludge containing fine powder to which PCB adheres. <P>SOLUTION: The PCB-containing oil sludge treatment method typically comprises the agitation process (S104) for storing and agitating a mixture liquid of the oil sludge containing fine powder to which PCB adheres and a PCB washing solvent in an agitation tank, a static separation process (S106) for precipitating the oil sludge by leaving the mixture liquid to stand for a predetermined time, and a solvent extraction process (S108) for extract supernatant solvent obtained after precipitating the oil sludge. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a PCB-containing oil mud treatment method for detoxifying oil mud containing fine powder to which PCB is attached.

  Polychlorinated biphenyl (hereinafter abbreviated as PCB) is a substance that has properties such as being chemically stable, difficult to decompose by heat, excellent electrical insulation, high boiling point, and nonflammability. . For this reason, in a wide range of fields, such as transformers, ballasts, switches, instrument transformers, capacitors, surge absorbers, circuit breakers, rectifiers, discharge coils, insulating oils used for reactors, heating media for boilers and heat exchangers, etc. Have been used. In Japan, about 59,000 tons of PCBs have been produced so far, of which about 54,000 tons have been used domestically (for example, Non-Patent Document 1).

  In recent years, the toxicity of PCBs to the human body has become apparent, and from 1972, no new PCBs have been manufactured in Japan. Furthermore, based on the “Law Concerning the Examination and Regulation of Chemical Substances” enacted in 1973, its production, import, etc. were virtually prohibited from 1974. Since then, in Japan, the disposal of PCB waste, including high-voltage transformers and high-voltage capacitors, has been stagnant, and has not been disposed of over a long period of time. In the prospect of such disposal is long-term storage is to continue without stand, the loss or the like occurs in the PCB waste, it has become a situation in which the progress of the environmental pollution is a concern.

  Therefore, the “Special Measures Law on Promotion of Proper Treatment of Polychlorinated Biphenyl Waste” was enacted in 2001, requiring PCB and waste oil containing PCB to be disposed of within 15 years.

  Various conventional PCB processing methods have been proposed. Representative examples include dechlorination decomposition method, hydrothermal oxidation decomposition method, reduction thermal decomposition method, photolysis method, plasma decomposition method, etc. There is.

As a step before processing the PCB itself, it is necessary to disassemble the device to which the PCB is attached for each member. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-334572) discloses a method for disassembling and cleaning a transformer containing PCB mixed insulating oil.
JP 2006-334572 A Ministry of the Environment “Polychlorinated biphenyl waste disposal basic plan” <Internet URL http://www.env.go.jp/recycle/poly/plan/180320.pdf>

  As described in Patent Document 1, in a PCB processing apparatus, it is necessary to disassemble equipment and parts to be processed before performing a cleaning process, and to crush some objects. Thus, when it decomposes | disassembles or crushes, a fine powder will generate | occur | produce and a washing process will be performed with adhering to to-be-processed object.

  The fine powder includes various things such as metal powder sludge, wood chips, paper powder, etc., and has a wide variety of materials and specific gravity. Large powders removed from the object to be processed by washing are separated by a strainer (40 mesh filter). However, those having a size of several nm to several μm cannot be separated by a strainer, and are introduced into a receiving tank or a distillation column together with a used solvent (cleaning liquid) and accumulated at the bottom thereof. This accumulated oil mud is discharged at every periodic inspection of the PCB processing apparatus.

  As described above, fine powder with fine particles tends to form a dense cake layer (a cake-like deposited layer formed by accumulation of suspended substances in the liquid). Since it is difficult for the solvent to naturally pass through the cake layer, the detoxification treatment is difficult even though it is deposited in the solvent. Accordingly, the oil mud discharged during the periodic inspection still has a very small amount of PCB to be treated.

  However, as described above, there is no method for appropriately treating oil mud composed of fine powder, and it has been difficult to treat PCB-containing oil mud that increases as the PCB processing apparatus operates.

  Therefore, an object of the present invention is to provide a PCB-containing oil mud treatment method suitable for detoxifying oil mud containing fine powder to which PCB is adhered.

  In order to solve the above problems, a typical configuration of the PCB-containing oil mud treatment method according to the present invention is to store a mixed liquid of oil mud containing fine powder to which PCB is adhered and a solvent for washing PCB in a stirring tank. It includes a stirring step of stirring, a stationary separation step of allowing the oil mud to settle by standing for a predetermined time, and a solvent extracting step of extracting the supernatant solvent after the oil mud has settled.

  According to the above configuration, the solvent and the oil mud are separated after detoxifying the oil mud containing the fine powder to which the PCB has adhered by including the stirring step and the stationary separation step of allowing the product to stand and settle. be able to. That is, when the oil mud is a very small fine powder of about several nanometers to several micrometers, clogging will occur if it is attempted to pass through while capturing with a filter, and the efficiency will be significantly reduced. Thus, the detoxification treatment can be performed at high speed and effectively.

  Alternatively, the PCB concentration of the extracted solvent may be measured, and the PCB concentration of the oil mud may be indirectly measured. Although it is difficult to directly measure the PCB concentration of the oil mud, the achievement of the detoxification treatment can be determined by the concentration of the eluted PCB. And when the PCB concentration contained in the solvent is more than the predetermined value, the solvent is replenished to the oil mud, and the detoxification process is completed by performing the stirring process, the stationary separation process, and the solvent extraction process. You can repeat until you do.

  A solvent storage tank for storing the extracted solvent, a suction pipe having one end connected to the solvent storage tank and the other end inserted into the solvent in the stirring tank, and a container shape attached to the tip of the suction tank on the stirring tank side and having an open top surface In the solvent extraction step, the solvent can be extracted in a state in which the liquid collection tank is partially embedded in the precipitate. When extracting the solvent in a state where the oil mud is precipitated in the agitation tank, the oil mud is a fine powder, and therefore the oil mud may be wound up and sucked by the flow of the solvent. On the other hand, since it is necessary to dry the oil mud finally, it is preferable to extract as much solvent as possible. Therefore, as described above, with the liquid collection tank partially immersed in the precipitate, suction from the inside of the liquid collection tank does not roll up the oil mud, and the solvent is very close to the surface of the oil mud. Can be aspirated.

  It includes an oil mud transfer step of transferring oil mud that has settled in the stirring tank to a measuring tank of a predetermined capacity and transferring the oil mud from the measuring tank to the liquid removal device after stopping the transfer from the stirring tank to the measuring tank. Also good. According to the above process, a certain amount of oil mud can be transferred to the liquid removal device very easily. At this time, oil mud made of fine powder is mixed with a solvent and has fluidity.

  In the oil mud transfer step, the oil mud transferred from the measuring tank may be filled in a filter cloth bag installed in the liquid removal apparatus. Although the capacity of the filter cloth bag may be limited, since the oil mud can be transferred by a certain amount according to the oil mud transfer step, the filter cloth bag can be suitably filled.

  In the reduced-pressure heat drying step, the filter cloth bag made of a flexible filter may be heat-dried while being filled with oil mud. By making the filter cloth bag a flexible filter, it is easier to adopt a finer filter than a hard one. In addition, by using a replaceable bag body, batch processing is easier than a stationary filter.

  The oil mud transferred to the dewatering device may be heated and decompressed to vaporize the solvent and dry to reduce the solvent and dry. Since the oil mud is a fine powder with extremely small particles, there is a problem in that drainage by pressing causes clogging of the filter at an early stage and efficiency does not increase. However, if the solvent is vaporized by heating and depressurization, it can pass through the filter smoothly, so that it can be drained and dried without clogging.

In the reduced pressure heating and drying step, the heating temperature may be 60 ° C. or lower. In particular, when undecane (C ₁₁ H ₂₄ ) is used as a solvent, the flash point is 70 ° C., and therefore, it is preferably set to 60 ° C. or less in consideration of safety. If the oxygen concentration is reduced due to the reduced pressure, it will not ignite even if it becomes 100 ° C. or higher, but it is desirable to consider the case where air is mixed.

  In the reduced-pressure heating and drying step, the filter cloth bag may be mounted on the mounting table, and heated to be in contact with the filter cloth bag by heating the mounting table. Even when heated from the outer wall of the dewatering device in a reduced pressure state, it is difficult to heat the oil mud because there is almost no air to be a heat transfer medium. Therefore, by heating the mounting table for the filter cloth bag, it is possible to directly heat the mounting table in contact with the filter cloth bag.

  In the vacuum heating and drying step, the entire surface of the filter cloth bag may be dried while being pressed toward the mounting table of the filter cloth bag. Here, the compression of the filter cloth bag is actually accompanied by drainage by squeezing, but is mainly intended for molding during drying. That is, when the solvent in the filter cloth bag is vaporized and drained, the filter cloth bag (that is, oil mud) can be formed flat by pressing the filter cloth bag. As a result, the filter cloth bag can be shaped into a specified bucket, and can be applied to the existing PCB graduation judgment device of the PCB processing device that performs the PCB detoxification processing of the equipment. There is no need to provide it.

  A heating device capable of controlling the temperature independently above and below the tilt direction is placed on the tilted mounting table, and when the temperature of the heating device rises above a predetermined temperature, the temperature of the upper heating device is lowered or stopped. You may let them. First, the oil mud can be smoothly introduced into the filter cloth bag by inclining the mounting table for the filter cloth bag downward with respect to the oil mud entering direction. However, when the mounting table is inclined, when the liquid removal proceeds, more solvent remains in the lower part than in the upper part, and the upper part is dried first. Therefore, as described above, the heating device can be controlled independently from above and below, and when the upper part is dried, the heating can be reduced or stopped to efficiently drain the liquid.

  It is equipped with a condenser that liquefies and condenses the generated steam.In the vacuum heating and drying process, the condenser inlet temperature is monitored and recovered as water while the temperature is high. It may be recovered as there is. Oil and mud contain water as well as solvent, but water is discarded and the solvent is distilled and reused. The water evaporates first because of the difference in vapor pressure between water and solvent, but when the water evaporation is completed, the flow of the vapor is interrupted until the solvent evaporation starts, so the inlet temperature of the condenser decreases. Therefore, by detecting this temperature drop, water and solvent can be separated and recovered.

  The present invention can also be used when the oil mud contains both fine powder having a specific gravity smaller than that of the solvent for washing PCB and fine powder having a large specific gravity. A fine powder having a specific gravity smaller than that of a solvent for washing PCB has a problem that it floats in the solvent and hardly settles even after a predetermined time. However, when it is stirred together with a fine powder having a large specific gravity, it is experientially settled, so that oil mud can be separated efficiently at high speed.

  According to the PCB-containing oil mud treatment method according to the present invention, the oil mud containing very small fine powder of about several nm to several μm on which PCB is adhered is detoxified at high speed and effectively, and then the solvent and the oil mud are separated. Can be made.

  Embodiment of the PCB containing oil mud processing method concerning this invention is described. The dimensions, materials, and other specific numerical values shown in the following embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified.

[PCB processor]
FIG. 1 is a diagram showing a schematic configuration of a device that performs PCB detoxification processing of equipment, and “oil mud containing fine powder to which PCB is attached” is generated as a processing target of the PCB-containing oil mud processing device according to this embodiment The process will be described.

  A PCB processing apparatus 500 shown in FIG. 1 is a facility for cleaning and recycling a pole transformer as an example of a device to be processed. The PCB processing apparatus 500 is roughly divided into an acceptance dismantling facility 510, a cleaning facility 520, a determination facility 530, and a dispensing facility 540.

  In the receiving and dismantling facility 510, the equipment received in the temporary storage 512 is disassembled in the dismantling line 514 according to materials such as insulators, metals, cases (iron), and wood. Particularly in a columnar transformer, an iron core and a copper coil are disassembled in a separator 516. These dismantled and separated objects to be processed are classified by material, and are transferred to the cleaning machine 522 of the cleaning facility 520 in a state of being put in a bucket (not shown) having a predetermined shape and capacity.

In the cleaning facility 520, the workpiece is immersed in the solvent together with the bucket in the cleaning machine 522. PCB is mainly attached to the surface of the object to be processed and is cleaned by immersion cleaning and ultrasonic cleaning. Various known solvents can be used as the solvent used for cleaning, and for example, an organic compound such as undecane (C ₁₁ H ₂₄ ) can be used. Since the insulating paper is wound around the coil, it is transported to the crusher / sorter 524 after washing to separate and sort copper and insulating paper, and then the copper wire is washed again in the copper secondary washing machine 525. . The separated insulating paper can be detoxified at high temperature by incineration. The cleaned object to be processed and the secondary-cleaned copper wire of the coil are conveyed to the determination device 532 of the determination facility 530.

  In the determination facility 530, the determination device 532 determines graduation (whether or not the cleaning is completed) by immersing the object to be processed after cleaning in a solvent and measuring the PCB concentration of the solvent. If it passes the graduation judgment, it will be paid out after being temporarily stored in the pre-payment storage 542 of the payout equipment 540, and the reusable material will be carried out to the recycle equipment, and the non-reusable material will be incinerated as industrial waste, etc. Appropriate processing is applied.

  In the PCB processing apparatus having the above-described configuration, the solvent used in the cleaning machine 522 or the secondary copper cleaning machine 525 is collected in the used solvent receiving tank 527, regenerated in the distillation column 528, and then recycled for reuse. Is done. On the other hand, debris containing fine powder is attached to the object to be processed or decomposed in the receiving and dismantling facility 510, and is mixed with the solvent by washing and collected together with the solvent. A strainer 526 is disposed between the washing machine 522 and the copper secondary washing machine 525 and the receiving tank 527, and large pieces are collected by a 40 mesh filter. However, those having a size of several nm to several μm cannot be separated by the strainer 526 and are introduced into the receiving tank 527 and the distillation column 528 together with the solvent after use and accumulated at the bottom thereof. The accumulated fragments are discharged as oil mud every periodic inspection of the PCB processing apparatus.

  Oil mud contains fine powder with PCB attached, and fine powder contains various things such as metal powder sludge, wood chips, paper powder, and various materials and specific gravity. Although the concentration of PCB is lowered because it is immersed in a solvent in the washing machine 522 and the copper secondary washing machine 525, it is not completely removed, and a very small amount of PCB remains to be processed. is doing. Therefore, the present invention treats oil mud by the following PCB-containing oil mud treatment apparatus and PCB-containing oil mud treatment method.

[PCB-containing oil mud treatment apparatus and PCB-containing oil mud treatment method]
2-4 is a figure which shows the PCB containing oil mud processing apparatus concerning this embodiment, FIG. 2 is a front view of a PCB containing oil mud processing apparatus, FIG. 3 is a side view of a PCB containing oil mud processing apparatus, FIG. It is a top view of a PCB containing oil mud processing apparatus.

  The PCB-containing oil mud processing apparatus (hereinafter simply referred to as “processing apparatus 100”) shown in FIGS. 2 to 4 is roughly divided into a stirring / separating unit 200, a metering transfer unit 220, and a liquid removal drying unit 240. .

  As shown in FIG. 2, oil mud containing fine powder with PCB attached is accommodated in a drum can 102 and carried into the stirring separation unit 200. The drum can 102 is moved to the stirring tank 204 by the roller conveyor 202, and is tilted while being lifted by the power cylinder 206, and the oil mud is put into the stirring tank 204. In addition, a solvent for washing PCB is introduced into the stirring tank 204 in the same amount as that of oil mud, for example. The solvent used here is preferably the same material as the solvent used in the PCB processing apparatus 500 described above.

  The agitation tank 204 includes an agitation device 208 for agitating the stored oil mud and solvent mixture, and a solvent extraction device 210 for extracting the supernatant solvent after the oil mud settles. The agitation tank 204 includes a lid 204a, and is configured to close the lid during agitation.

  The stirring device 208 includes a stirring blade 208b at the tip of the drive shaft of the motor 208a. The stirring blade 208b is disposed in the vicinity of the bottom of the stirring tank 204, and mechanically stirs by generating a downward flow in the stored mixed liquid. On the other hand, an inclined surface 204b is formed on the bottom surface of the stirring tank 204 at a position facing the downward flow by the stirring device 208, and the downward flow is converted into an upward flow along the inclined surface 204b. Thereby, the flow which circulates the whole inside of a stirring tank is produced | generated, and it can stir better.

  As shown in FIG. 3, the solvent extraction device 210 includes a solvent storage tank 212 installed below the stirring tank, and a suction pipe having one end connected to the solvent storage tank 212 and the other end inserted into the solvent in the stirring tank 204. 214.

  A process of treating PCB adhered to oil mud using the stirring tank 204, the stirring device 208, and the solvent extraction device 210 having the above-described configuration will be described. FIG. 5 is a flowchart for explaining the oil mud cleaning step, and FIG. 6 is a schematic diagram for explaining the state of the oil mud and the solvent in the stirring tank.

  First, oil mud and a solvent are charged and stored in the stirring tank 204 (S102), and the mixed solution is stirred for a predetermined time (for example, 1 hour) using the stirring device 208 as shown in FIG. 6A (stirring step: S104). ). The rotation speed of the stirring blade 208b can be set to 200 rpm, for example. As shown in FIG.6 (b), it leaves still for predetermined time (for example, 12 hours), and oil mud is settled (stationary separation process: S106). As shown in FIG.6 (c), the solvent of the supernatant after oil mud settles is extracted (solvent extraction process: S108).

  Next, the PCB concentration of the extracted solvent is measured (S110), and it is determined whether or not it is below the reference value (S112). If it is equal to or higher than the reference value, the stirring tank is replenished with the solvent again as shown in FIG. repeat. If it is below the reference value, it is discharged from the outlet 204c (see FIG. 2) of the stirring tank 204 to the measuring tank (S116). At this time, the stirring blade 208b smoothly sends oil mud by performing ultra-low speed rotation of about several rpm.

  According to the said structure, after detoxifying the oil mud containing the fine powder to which PCB adhered, a solvent and oil mud can be isolate | separated. In other words, when the oil mud is a very small fine powder of several nm to several μm, if it tries to pass through while trapping with a filter, clogging will occur and the efficiency will be significantly reduced. By carrying out sedimentation by standing, separation can be performed quickly and effectively. In general, fine powder having a specific gravity smaller than that of a solvent such as paper powder is slow to settle, but it is found that the fine powder settles early by stirring together with a fine powder having a specific gravity larger than that of a solvent such as metal powder. It is thought that this can promote sedimentation by winding up the metal powder etc. which collected on the bottom part by stirring, adhering the paper powder etc. which float in a solvent, or disperse | distributing paper powder.

  In addition, it is difficult to directly measure the PCB concentration of the oil mud, but by measuring the PCB concentration of the extracted solvent, it is possible to indirectly measure the PCB concentration of the oil mud to determine the achievement of the detoxification process. it can.

  Note that the suction pipe 214 can move up and down at the tip on the stirring tank 204 side, and can enter the solvent from above. By lowering the suction pipe according to the height of the accumulated oil mud, it is possible to suck the solvent near the surface of the accumulated oil mud.

  FIG. 7 is a view for explaining a liquid collecting tank provided at the tip of the suction pipe 214. As shown in FIG. 7 (a), a container-like liquid collecting bowl 214a having an open upper surface is provided at the tip of the suction pipe 214 on the stirring tank 204 side. By sucking the suction pipe 214 from the inside of the liquid collection tank 214a, it is possible to prevent the oil mud from being rolled up by the flow of the solvent during the suction. In particular, as shown in FIG. 7 (b), in a state where the liquid collecting tub 214a is partially embedded in the precipitate (oil mud), the oil mud is not rolled up by being sucked from the inside of the liquid collecting tub 214a. In addition, it is possible to suck even a solvent very close to the surface of the oil mud.

  The metering transfer unit 220 transfers oil mud from the agitation tank to the dewatering drying unit 240, and opens and closes a metering tank 224 having a predetermined capacity and a path between the stirring tank 204 and the metering tank 224. 1 valve 222 and the 2nd valve 226 which opens and closes the path | route between the measurement tank 224 and the liquid removal apparatus.

  By opening the first valve 222, the oil mud precipitated in the stirring tank 204 is transferred to the measuring tank 224. At this time, the second valve 226 is in a closed state. When the measuring tank 224 is filled, the first valve 222 is closed. And by opening the 2nd valve | bulb 226, an oil mud is transferred to the liquid removal drying part 240 (oil mud transfer process). Here, since the measuring tank 224 has a predetermined capacity (for example, 10 liters), a certain amount of oil mud can be transferred very easily. In addition, it is preferable to make this capacity | capacitance below the capacity | capacitance of the filter cloth bag mentioned later.

  The measuring tank 224 has an air vent pipe 228 whose upper end is located above the liquid level of the mixed liquid in the stirring tank 204. Accordingly, when oil mud is transferred from the stirring tank 204 to the measuring tank 224, it is possible to prevent oil mud from overflowing from the measuring tank 224 even if the first valve 222 is delayed.

  The liquid removal drying unit 240 includes a liquid removal apparatus 250, a decompression apparatus 260, a heating apparatus 262, and a condenser 264. FIG. 8 is a diagram for explaining the configuration of the liquid removal apparatus.

  As shown in FIG. 8, the dewatering device 250 has a lid 252 that can be opened and closed by a hydraulic device 242, and the lid 252 can be closed and sealed to form a vacuum container. In addition, a mounting table 254 for mounting the filter cloth bag 280 is provided inside the liquid removal apparatus 250, and the oil mud transferred from the metering transfer unit 220 is filled into the filter cloth bag 280. The mounting table is inclined by about 15 ° or more downward with respect to the entry direction of the oil mud, and the oil mud can be smoothly introduced into the filter cloth bag 280. Although the inclination angle depends on the viscosity of the oil mud, if it is 15 ° or less, the fluidity is poor and it is difficult to smoothly fill the filter cloth bag 280. On the other hand, the heatability and the moldability (flatness) of the filter cloth bag are preferably as the inclination angle is smaller. For this reason, the inclination is preferably about 15 ° with respect to the horizontal.

  The filter cloth bag is a bag formed by a flexible filter. A filter having flexibility is easier to adopt a finer filter than a hard filter, and it is easy to remove clogging by washing. In addition, by using a replaceable bag body, batch processing is easier than a stationary filter. As a specific example of the filter cloth bag, a very fine bag of coal ash mesh can be used.

  Further, the lid 252 includes a closing member 252 a that presses and seals the opening of the filter cloth bag 280, and a compression plate 252 b that compresses almost the entire surface of the filter cloth bag 280 toward the mounting table 254. The pressure plate 252b presses the filter cloth bag 280 when the solvent in the filter cloth bag 280 is vaporized and drained, thereby forming the filter cloth bag 280 (that is, oil mud) flatly. Further, the compression plate 252b has a large number of openings, and the solvent leaking from the surface of the filter cloth bag 280 can be smoothly flowed out by squeezing with the compression plate 252b. As an example of the compression plate having a large number of openings, it can be composed of a punching metal, a net, a frame or the like.

  Both the closing member 252a and the compression plate 252b are biased toward the filter cloth bag 280 by a spring member. The closing member 252a is disposed so as to protrude toward the filter cloth bag 280 rather than the compression plate 252b. Further, the urging force of the closing member 252a is set to be stronger than the urging force of the compression plate 252b. As a result, the entire surface of the filter cloth bag 280 can be pressed while the opening of the filter cloth bag 280 is sealed by one setup of closing the lid of the liquid removal apparatus. Although a coil spring is illustrated as the spring member, other elastic members such as a leaf spring may be used. The biasing member that biases the closing member 252a and the compression plate 252b is not limited to an elastic member, and may be a pressing member using a link mechanism, for example.

  The heating device 262 is provided on the lower surface of the mounting table 254 and heats the filter cloth bag 280 directly by heating the mounting table 254. Even when heated from the outer wall of the dewatering device 250 in a reduced pressure state, it is difficult to heat the oil mud because there is almost no air to be a heat transfer medium. Therefore, heat can be efficiently transferred by heating the mounting table 254 of the filter cloth bag 280. Further, the heating device 262 is provided in two divided above and below the inclination direction of the mounting table 254, and the temperature can be controlled independently.

  As shown in FIG. 4, a depressurization device 260 is connected to the liquid removal device 250 via a condenser 264 and a first drain recovery pot 268. The steam discharged from the liquid removal device 250 is liquefied by the condenser 264 and accumulated in the first drain recovery pot 268 as water or a solvent.

  Further, as shown in FIG. 3, a second drain recovery pot 270 is connected to the liquid removal device 250 and is configured to collect the solvent and water dripped in the liquid removal device 250.

  FIG. 9 is a flowchart for explaining the reduced pressure heating drying process. First, the filter cloth bag 280 is set on the mounting table 254 in the liquid removal apparatus 250 (S202), and oil mud is introduced from the measuring tank 224 (S204). Although the capacity of the filter cloth bag 280 is limited, according to the oil mud transfer step, the oil mud can be transferred in a certain amount, and therefore the filter cloth bag can be suitably filled.

  Next, the hydraulic device 242 is operated and the drainage device 250 is sealed by closing the lid 252, and the opening of the filter cloth bag 280 is pressed and sealed with the closing member 252 a (S 206), and the compression plate 252 b is also sealed. Thus, the entire surface of the filter cloth bag 280 is pressed (S208). The filter cloth bag 280 is clogged immediately because the oil mud is a fine powder with very small particles, but a small amount of water or solvent is squeezed and drained. The liquid dropped at this time is recovered in the second drain recovery pot.

  Next, while heating by the heating device 262, the inside of the liquid removal device 250 is depressurized to a level close to vacuum by the decompression device 260 (reduced pressure heating drying step: S210). Even if the filter cloth bag 280 is clogged by the compression, it can pass through the filter smoothly if it is vaporized, so that it can be drained and dried regardless of whether or not it is clogged.

In the reduced pressure heating and drying step, the heating temperature is set to 60 ° C. or lower. In particular, when undecane (C ₁₁ H ₂₄ ) is used as a solvent, the flash point is 70 ° C., and therefore, it is preferably set to 60 ° C. or less in consideration of safety.

  When drying under reduced pressure proceeds, more solvent remains in the lower part than in the upper part, and the upper part is dried first. Therefore, the temperatures of the upper and lower heating devices 262 are respectively monitored (S212), and when the temperature of the upper heating device rises above a predetermined temperature (when the upper portion is dried), the heating is reduced or stopped (S214). . Thereby, it can drain efficiently.

  During the drying under reduced pressure, the inlet temperature of the condenser 264 is monitored (S216). When the temperature is high, it is recovered as water (S218). It collects as it exists (S220). Oil and mud contain water as well as solvent, but water is discarded and the solvent is distilled and reused. Water evaporates first because of the difference in vapor pressure between water and solvent, but when the evaporation of moisture is completed, the flow of vapor stops until the solvent starts to evaporate, so the inlet temperature of the condenser decreases. Also, since the solvent with low boiling point does not evaporate under the condition that water is present in the system, after the water has condensed in the condenser, the water is discharged out of the system, and then the degree of vacuum is increased to evaporate and recover the solvent. There is a need to do. Therefore, by detecting this temperature drop, water and solvent can be separated and recovered.

  Then, the vacuum heating and drying is continued for a predetermined time (S222), and when the predetermined time is continued, the heating and the pressure reduction are stopped (S224). The predetermined time can be roughly calculated from the latent heat and heat loss of water and solvent contained in the oil mud.

  Then, the filter cloth bag 280 that has been drained (dried) is taken out (S226). The filter cloth bag 280 is flat because it is dried while being compressed by the compression plate 252b, and can be accommodated in the bucket of the existing PCB processing apparatus 500. Then, it can be put into the cleaning machine 522 shown in FIG. 1 and applied to the PCB graduation determination device in the same manner as a normal object to be processed, and there is no need to newly provide a dedicated graduation determination device.

  The decompression device 260 may be provided with a water separator (not shown). This is because even if the liquid is liquefied by the condenser 264 and is recovered by the first drain recovery pot 268, the steam reaches the pressure reducing device 260 and is liquefied particularly when the capacity of the condenser 264 is insufficient. In particular, when the pressure reducing device 260 is an oil rotary vacuum pump, it is effective to provide a water separation device because the operating oil may float when water is mixed into the operating oil, leading to a malfunction.

  Further, as shown in FIG. 2, the exhaust duct 104 may be disposed above the stirring tank 204 or the liquid removal apparatus 250, and an activated carbon filter may be provided in the exhaust path from the exhaust duct. Thus, even if a small amount of PCB is mixed in the exhausted atmospheric gas, it can be reliably absorbed to prevent leakage.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the filter cloth bag 280 can scrape and reuse the internal oil mud, but when a coal ash bag is used as a filter cloth bag, it does not produce toxic gas even if burned, so it contains dried sludge It is also possible to dispose of it by incineration.

  INDUSTRIAL APPLICABILITY The present invention can be used as a PCB-containing oil mud treatment method for detoxifying oil mud containing fine powder to which PCB is attached.

It is a figure which shows schematic structure of the apparatus which performs the PCB detoxification process of an apparatus. It is a front view of a PCB containing oil mud processing apparatus. It is a side view of a PCB containing oil mud processing apparatus. It is a top view of a PCB containing oil mud processing apparatus. It is a flowchart explaining the washing | cleaning process of an oil mud. It is a schematic diagram explaining the state of the oil mud and solvent in a stirring tank. It is a figure explaining the liquid collection tank provided in the front-end | tip of the suction pipe. It is a figure explaining the structure of a liquid removal apparatus. It is a flowchart explaining a pressure reduction heating drying process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Processing apparatus, 102 ... Drum can, 104 ... Exhaust duct, 200 ... Agitation separation part, 202 ... Roller conveyor, 204 ... Agitation tank, 204a ... Lid, 204b ... Inclined surface, 204c ... Discharge port, 206 ... Power cylinder, 208 DESCRIPTION OF SYMBOLS ... Stirring device, 208a ... Motor, 208b ... Stirring blade, 210 ... Solvent extraction device, 212 ... Solvent storage tank, 214 ... Suction pipe, 214a ... Liquid collecting tank, 220 ... Metering transfer part, 222 ... First valve, 224 ... Measuring tank, 226 ... second valve, 228 ... air vent pipe, 240 ... dewatering drying section, 242 ... hydraulic device, 250 ... dewatering device, 252 ... lid, 252a ... closing member, 252b ... compression plate, 254 ... mounting table , 260 ... decompression device, 262 ... heating device, 264 ... condenser, 268 ... first drain recovery pot, 270 ... second drain recovery pot, 280 ... filter cloth bag 500 ... PCB processing equipment, 510 ... receiving and dismantling equipment, 512 ... temporary storage, 514 ... dismantling line, 516 ... separator, 520 ... cleaning equipment, 522 ... washing machine, 524 ... crusher / sorter, 525 ... two copper Next cleaning machine, 526 ... strainer, 527 ... receiving tank, 528 ... distillation tower, 530 ... judgment equipment, 532 ... judgment machine, 540 ... delivery equipment, 542 ... storage before delivery

Claims (7)

An agitation step of storing and agitating a mixed liquid of oil mud containing fine powder to which PCB is adhered and a solvent for washing PCB in an agitation tank;
A stationary separation step of allowing the oil mud to settle for a predetermined time;
A solvent extraction step of extracting the supernatant solvent after the oil mud has settled;
A PCB-containing oil mud treatment method comprising: Oil mud precipitated in the stirring tank is transferred to a measuring tank of a predetermined capacity and filled,
After stopping the transfer from the stirring tank to the weighing tank,
2. The PCB-containing oil mud treatment method according to claim 1, further comprising an oil mud transfer step of transferring oil mud from the measuring tank to the liquid removal device.   3. The PCB-containing oil mud treatment method according to claim 1, further comprising a reduced pressure heating and drying step of evaporating and drying the solvent by heating and depressurizing the oil mud transferred to the liquid removal device.   The PCB-containing oil mud treatment method according to claim 3, wherein the heating temperature is 60 ° C. or less in the reduced pressure heating and drying step. In the vacuum heating and drying step,
The PCB-containing oil mud treatment method according to claim 3 or 4, wherein the filter cloth bag made of a flexible filter is heated and dried in a state where oil mud is filled. In the vacuum heating and drying step,
The PCB-containing oil mud treatment method according to claim 5, wherein the entire surface of the filter cloth bag is dried while being pressed toward a mounting table for the filter cloth bag.   7. The oil mud according to any one of claims 1 to 6, wherein both the fine powder having a specific gravity smaller than that of the solvent for cleaning the PCB and the fine powder having a large specific gravity are included. The PCB-containing oil mud treatment method described.

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