JP2011227024A - Method and device for treating waste liquid containing boric acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method and a device for treating waste liquid containing a boric acid which can prevent a pipe from being clogged by a residue of a borate in washing waste liquid from a drying machine and achieve a stable long term treatment of the waste liquid containing a boric acid subject to cement solidification.SOLUTION: Waste liquid containing a boric acid which has become hardly-soluble is transferred to a tank 3 having a stirring machine 4 and stored therein. Next, the hardly-soluble waste liquid containing a boric acid is transferred from the tank 3 to a drying machine 7 to dry and separate a borate in the hardly-soluble waste liquid containing a boric acid. Then, cleaning water is supplied from a cleaning water tank 12 to wash the drying machine 7 and washing waste liquid containing a residue of the borate is transferred to the tank 3. Last, the residue of the borate is stirred and finely granulated by the stirring machine 4 in the tank 3.

Description

  Embodiments described herein relate generally to a method and apparatus for treating boric acid-containing waste liquid generated in a pressurized water reactor (PWR) or the like.

  Since the boric acid-containing waste liquid generated in a pressurized water reactor (PWR) or the like contains boric acid containing a radionuclide, it must finally be solidified with cement or the like. However, since boric acid prevents the cement from solidifying, there is a limit to the amount of boric acid that can be added to the cement. For this reason, a pretreatment is performed in which a boric acid-containing waste liquid is preliminarily added with a calcium compound such as calcium hydroxide to insolubilize boric acid and precipitate a borate such as calcium borate. A method is known in which an acid salt) is dried to be pulverized and cemented, thereby preventing boring acid from hindering cement solidification.

  However, the above-described method has a problem that the viscosity of the boric acid-containing waste liquid increases, and calcium borate settles and accumulates in a staying portion or the like in the pipe and the pipe is blocked. For this reason, an alkali metal element compound and an alkaline earth metal compound are added to a boric acid-containing waste liquid heated to 80 ° C., and the waste liquid is allowed to flow through the piping while being kept at a temperature equal to or higher than the precipitation temperature, and supplied to the dryer. There has been proposed a method of suppressing sedimentation or the like to a staying portion in a pipe by performing a drying process (for example, see Patent Document 1).

  However, even with the above technique, the addition of an alkali metal element compound and an alkaline earth metal compound to the boric acid-containing waste liquid increases the viscosity of the waste liquid, and may settle and accumulate in the staying part in the pipe. There was still a problem that the piping would be blocked.

  In view of such a situation, in Patent Document 2, paying attention to the temperature of the boric acid-containing waste liquid when adding the alkali metal element compound and the alkaline earth metal compound, the alkali metal element compound is added to the boric acid-containing waste liquid. After the addition, the temperature of the boric acid-containing waste liquid is raised to a temperature of 85 ° C. or higher, and then the alkaline earth metal compound is added and stirred to suppress an increase in the viscosity of the boric acid-containing waste liquid. Various problems such as blockage of piping as described above are solved.

  According to such a method, an increase in the viscosity of the boric acid-containing waste liquid can be drastically suppressed as compared with the conventional method, and the problem of blockage of the pipe due to sedimentation and accumulation of the waste liquid in the pipe is to some extent. Can be improved.

  On the other hand, after the precipitate (borate) is dried and used for cement solidification with a dryer, the inside of the dryer is washed with washing water. Since the cleaning waste liquid generated at this time contains the residue of the precipitate, it is transferred to a tank for storing the boric acid-containing waste liquid, and again subjected to the above-described steps. Acid salt) will be dried and separated again. In this case, when the size of the residue contained in the cleaning waste liquid is increased, the piping for transferring from the dryer to the storage tank, and the transfer from the storage tank to the dryer in the case of being used again in the above-described process are transferred. The residue may block the piping at the time.

  Patent Documents 1 and 2 described above disclose a technique for preventing clogging of pipes by precipitates (borate) contained in boric acid-containing waste liquid, but precipitates (borate) contained in cleaning waste liquid. There is no disclosure of a technique for preventing the clogging of pipes due to the residue.

JP 2000-284092 A JP 2005-345440 A

  The present invention is a novel boron which prevents clogging of piping due to borate residues contained in the washing waste liquid of the dryer, and can stably treat the boric acid-containing waste liquid used for cement solidification for a long period of time. It aims at providing the processing method and processing apparatus of an acid containing waste liquid.

  In order to solve the above-described problem, one aspect of the present invention is a method for treating a boric acid-containing waste liquid to be cement-solidified, and depositing insoluble borate in the boric acid-containing waste liquid in a first tank. The step of hardly solubilizing, the step of transferring and storing the hardly soluble boric acid-containing waste liquid in a second tank having a stirrer, and the hardly soluble solubilized boric acid-containing waste liquid, Transferring from the tank to the dryer, drying and separating the borate contained in the hardly soluble boric acid-containing waste liquid, and supplying the washing water from the washing water tank to wash the dryer, The step of transferring the cleaning waste liquid containing the borate residue into the second tank and the stirring by the stirrer provided in the second tank make the borate residue fine. And characterized by comprising steps Relates to a process for the treatment of boric acid-containing waste liquid.

  Another embodiment of the present invention is an apparatus for treating a boric acid-containing waste liquid that solidifies cement, wherein the boric acid-containing waste liquid is made insoluble by causing insoluble borate to precipitate. And storing the hardly-solubilized boric acid-containing waste liquid transferred from the first tank, a second tank having a stirrer, and the hardly-solubilized boric acid-containing waste liquid transferred from the second tank A cleaning waste liquid containing a borate residue, comprising: a dryer for drying and separating the borate contained therein; and a cleaning water tank for supplying cleaning water to the dryer for cleaning. Boric acid transported into the second tank and boric acid residue is finely divided by stirring with the stirrer provided in the second tank. The present invention relates to a treatment device for contained waste liquid.

  According to the said aspect, the borate residue contained in the washing | cleaning waste liquid produced when wash | cleaning a drying machine is refined by stirring by the stirrer provided in the 2nd tank which stores a boric acid containing waste liquid. Like to do. Therefore, when the boric acid-containing waste liquid containing such a residue is transferred from the second tank to the dryer and dried and separated, the piping related to the transfer of the residue is not blocked. . For this reason, it becomes possible to treat the boric acid containing waste liquid used for cement solidification stably for a long period of time.

  In addition, when the residue is agitated and refined, the borate in the boric acid-containing waste liquid is also refined at the same time by agitation, so that the piping related to the borate transfer is blocked. Can be suppressed.

  The refining by stirring the residue and borate is considered to be because shearing force generated when stirring the boric acid-containing waste liquid acts on the residue and borate.

  In an example of the present invention, the hardly-solubilized boric acid-containing waste liquid stored in the second tank is circulated through a pump, and borate and borate residues in the hardly-solubilized boric acid-containing waste liquid are removed. It can be made fine by the shearing force of the pump. In this case, the borate can be sufficiently fined in advance by the above-described stirring and the shearing force generated by the pump, and the size of the borate residue in the dryer can be sufficiently reduced in advance. I can keep it. Further, the borate residue can be sufficiently finely divided by using the shearing force of the pump in addition to the stirring by the stirrer. Therefore, it becomes possible to more effectively prevent the clogging of the piping related to the transfer and to stably treat the boric acid-containing waste liquid used for cement solidification for a long period of time.

  Moreover, in an example of this invention, the grinding apparatus with respect to the hardly soluble boric acid containing waste liquid stored in the 2nd tank can be provided on the circulation line of the 2nd tank containing the pump. In this case, the pulverization apparatus can pulverize and fine-bore borate and borate residues in the sparingly soluble boric acid-containing waste liquid stored in the second tank. For this reason, in addition to stirring with a stirrer, the borate salt and the residue can be sufficiently finely divided using pulverization by a pulverizer. Therefore, it becomes possible to more effectively prevent the clogging of the piping related to the transfer and to stably treat the boric acid-containing waste liquid used for cement solidification for a long period of time.

  Furthermore, in an example of the present invention, a pulverizing apparatus for boric acid-containing waste liquid that is hardly soluble can be provided between the second tank and the dryer. In this case, in addition to the stirring by the stirrer, the borate of the sparingly soluble boric acid-containing waste liquid stored in the second tank can be pulverized and sufficiently finely divided by pulverization by the pulverizer. For this reason, since the size of the residue in the dryer can be sufficiently reduced in advance, blockage of the piping related to the transfer of the hardly soluble boric acid-containing waste liquid and the residue is more effectively prevented, and the cement is solidified. The boric acid-containing waste liquid to be provided can be treated stably for a long period of time.

  Furthermore, in an example of the present invention, a filter for the hardly soluble boric acid-containing waste liquid can be provided between the second tank and the dryer. Moreover, the additional filter with respect to the sparingly soluble boric acid containing waste liquid stored in the 2nd tank can be provided on the circulation line of the 2nd tank containing a pump. In this case, borate and its residue exceeding the specified range can be removed from the boric acid-containing waste liquid, so that blockage of piping related to transfer can be more effectively prevented, and the borate used for cement solidification can be removed. The acid-containing waste liquid can be treated stably for a long period of time.

It is a figure which shows schematic structure of the processing apparatus of the boric acid containing waste liquid in 1st Embodiment. It is a figure which shows schematic structure of the processing apparatus of the boric acid containing waste liquid in 2nd Embodiment. It is a figure which shows schematic structure of the 1st modification of the processing apparatus of the boric-acid containing waste liquid in 2nd Embodiment. It is a figure which shows schematic structure of the 2nd modification of the processing apparatus of the boric-acid containing waste liquid in 2nd Embodiment. It is a figure which shows schematic structure of the 3rd modification of the processing apparatus of the boric acid containing waste liquid in 2nd Embodiment. It is a figure which shows schematic structure of the processing apparatus of the boric acid containing waste liquid in 3rd Embodiment. It is a figure which shows schematic structure of the modification of the processing apparatus of the boric acid containing waste liquid in 3rd Embodiment. It is a figure which shows schematic structure of the processing apparatus of the boric acid containing waste liquid in 4th Embodiment. It is a figure which shows schematic structure of the modification of the processing apparatus of the boric acid containing waste liquid in 4th Embodiment. It is a graph which shows the relationship between the stirring time and solid content rate in an Example. It is a graph which shows the relationship with the abundance ratio of the solid content after the stirring process in an Example. It is a figure which shows schematic structure of the processing apparatus of the boric-acid containing waste liquid in the modification of embodiment of this invention. It is a flowchart which shows the processing method of a boric-acid containing waste liquid using the processing apparatus shown in FIG.

  Hereinafter, the details and other features of the boric acid-containing waste liquid processing method and processing apparatus of the present invention will be described based on embodiments with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a boric acid-containing waste liquid treatment apparatus in the present embodiment. As shown in FIG. 1, the processing apparatus of this embodiment includes a pretreatment tank (first tank) 1 and a storage tank (second tank) 3 connected to the pretreatment tank 1 via a pipe 21. And have. Furthermore, it has a head tank 6 connected to the storage tank 3 via a pipe 22, and a dryer 7 connected to the head tank 6 via a pipe 23. Furthermore, the dryer 7 and the washing water tank 12 connected through the pipes 23 and 24 are provided.

  A heater 14 is installed on the side surface of the pretreatment tank 1, and the side surface temperature is maintained at about 95 ° C. or more, thereby preventing moisture from adhering to the radioactive waste liquid introduced into the pretreatment tank 1. Moreover, the 1st stirrer 2 for accelerating | stimulating the poorly soluble process demonstrated below is provided in the pre-treatment tank 1.

  The storage tank 3 is provided with a second stirrer 4 for stirring and refining the borate in the boric acid-containing waste liquid described below and the borate residue transferred from the dryer 7. It has been.

  Further, the pipe 22 is provided with a pump 5, and pressure gauges 10 and 11 are arranged before and after the pump 5 to monitor the pressure before and after the pump 5 to control the driving force of the pump 5.

  Next, a boric acid-containing waste liquid treatment method using the treatment apparatus shown in FIG. 1 will be described with reference to FIG. First, the boric acid-containing waste liquid is introduced into the pretreatment tank 1, and the boric acid-containing waste liquid is insolubilized (S1). This poorly soluble treatment can be performed, for example, by adding an alkaline earth metal compound to the boric acid-containing waste liquid. As a result, insoluble borate, such as calcium borate, is precipitated in the boric acid-containing waste liquid, which makes the boric acid-containing waste liquid hardly soluble.

  An appropriate amount of the alkali metal compound can be added before and after the addition of the alkaline earth metal compound. In this case, sedimentation of the precipitate obtained as described above, that is, borate can be prevented.

  The addition amount of the alkali metal compound is set so that the molar ratio of the alkali metal in the alkali metal compound to boron in the boric acid-containing waste liquid is 0.25 to 0.35, preferably 0.3. For example, in the case of NaOH, Na / B (molar ratio) = 0.25 to 0.35, preferably 0.3, and in the case of KOH, K / B (molar ratio) = 0.25 to 0.35, preferably Is 0.3.

  The addition amount in the case of an alkaline earth metal compound is such that the molar ratio of the alkaline earth metal in the alkaline earth metal compound to boron in the boric acid-containing waste liquid is 0.40 to 0.50, preferably 0.45. Set as follows. For example, in the case of CaOH, Ca / B (molar ratio) = 0.40 to 0.50, preferably 0.45.

  In the pretreatment tank 1, the side surface of the pretreatment tank 1 is heated to 95 ° C. or higher by the heater 14 so that moisture in the boric acid-containing waste liquid does not adhere to the side wall.

  In addition, when the alkaline earth metal compound and further the alkali metal compound are added to make the solution hardly soluble, the boric acid-containing waste liquid is made slightly soluble by the first stirrer 2 provided in the pretreatment tank 1. Stir for several hours until

  Next, the boric acid-containing waste liquid that has been sparingly soluble in the pretreatment tank 1 is transferred to the storage tank 3 and stored (S2). Thereafter, the pump 5 is transferred to the head tank 6 via the pipe 22 and once stored, and then transferred from the head tank 6 to the dryer 7 via the pipe 23 (S3).

  The liquid level gauge 8 is provided in the head tank 6, and when the hardly soluble boric acid-containing waste liquid exceeding the allowable amount is introduced into the head tank 6, the allowable amount of the hardly soluble boric acid-containing waste liquid is exceeded. The minute is returned to the storage tank 3 via the pipe 24. Similarly, a flow meter 9 is provided in the pipe 23 so that the amount of hardly soluble boric acid-containing waste liquid to be supplied from the head tank 6 to the dryer 7 is controlled in consideration of the drying capacity of the dryer 7. I have to.

  In the dryer 7, for example, borate is precipitated from the introduced hardly-solubilized boric acid-containing waste liquid by a heater, heating steam or the like (not shown), and dried and separated (S4). The separated borate is taken out from the dryer 7 through the valve 7A and used for cement solidification.

  On the other hand, after the drying process is performed in the dryer 7, washing water is introduced into the dryer 7 from the washing water tank 12 through the pipes 27 and 23 by the pump 13, and the inside of the dryer 7 is cleaned (S5). ). At this time, since a residue of precipitated and dried borate is present in the dryer 7, the residue is contained in the cleaning waste liquid generated after the dryer 7 is cleaned. . Since this residue is radioactive, the cleaning waste liquid containing such residue is transferred to the storage tank 3 via the pipe 25.

  Thereafter, the residue is transferred to the dryer 7 again through the above-described steps together with the hardly-solubilized boric acid-containing waste liquid supplied from the pretreatment tank 1, and dried and separated.

  At this time, when the residue is relatively large, the pipe 25 may be blocked when the cleaning waste liquid containing the residue is transferred from the dryer 7 to the storage tank 3. Moreover, when transferring from the storage tank 3 to the dryer 7, the pipes 22 and 23 may be blocked. Therefore, in the present embodiment, after the cleaning waste liquid containing the residue is transferred into the storage tank 3 (S6), the waste liquid stored in the storage tank 3 by the second stirrer 4 provided in the storage tank 3 is used. Agitation is performed to refine the residue (S7).

  Accordingly, at least when the residue is transferred from the storage tank 3 to the dryer 7 together with the hardly soluble boric acid-containing waste liquid, it is possible to prevent the pipes 22 and 23 from being blocked. In addition, even when the residue remains in the dryer 7 again, the residue is already finely divided, so that the cleaning waste liquid containing the residue is piped when the inside of the pipe 25 is transferred. 25 occlusions can be suppressed.

  Thus, in this embodiment, since the blockage of the piping in the residue in the dryer 7 can be suppressed, it becomes possible to stably treat the boric acid-containing waste liquid used for cement solidification for a long period of time. .

  Further, insoluble boric acid in the waste liquid containing sparingly soluble boric acid supplied from the pretreatment tank 1 to the storage tank 3 as well as the above residue by stirring by the second stirrer 4 provided in the storage tank 3. Since the salt can also be finely divided in advance, it is possible to suppress the blockage of the pipes 22 and 23 due to the borate when initially transferring from the storage tank 3 to the dryer 7. Furthermore, since the size of the residue in the dryer 7 can be reduced as the borate is refined, the blockage of the pipe 25 during transfer from the dryer 7 to the storage tank 3 is also suppressed. can do.

  That is, when the processing apparatus shown in FIG. 1 is used, not only clogging of the piping due to borate residue in the dryer 7 but also the initial insoluble borate contained in the boric acid-containing waste liquid is refined. Since it can be granulated, it is possible to obtain an additional effect that the blockage of the pipe by the insoluble borate can be suppressed.

The stirring speed of the storage tank 3 by the second stirrer 4 is preferably 155 times / minute or more. The stirring power of the second stirrer 4 can be 0.28 kW / m ³ or more. Thereby, the residue can be sufficiently refined by the second stirrer 4, and the original insoluble borate contained in the boric acid-containing waste liquid can be sufficiently refined.

In addition, although the stirring speed and stirring power of the 2nd stirrer 4 will not be specifically limited if it is more than the said lower limit, each upper limit can be 500 times / min and 1.10 kW / m < ³ >.

  The agitation speed and agitation power in the second agitator 4 can be realized by controlling the driving force of the second agitator 4. For example, the storage tank 3 is provided with a vertical movement mechanism (not shown). Therefore, it can be controlled to some extent by moving the second stirrer 4 up and down. That is, when the amount of the boric acid-containing waste liquid in the storage tank 3 is large, the stirring speed and stirring power can be increased by arranging the second stirrer 4 near the liquid level of the waste liquid by the vertical movement mechanism. be able to.

  In the present embodiment, the hardly-solubilized boric acid-containing waste liquid stored in the storage tank 2 can be circulated through the pipe 26 by the pump 5. In this case, the borate in the hardly soluble boric acid-containing waste liquid in the storage tank 3 and the residue from the dryer 7 can be finely divided by the shearing force of the pump.

  Therefore, the borate in the hardly-solubilized boric acid-containing waste liquid can be sufficiently finely divided in advance by the stirring by the second stirrer 4 and the shearing force of the pump 5, and the borate in the dryer 7 can be finely divided. The size of the residue can be sufficiently reduced in advance. Moreover, the borate residue transferred and stored in the storage tank 3 can be sufficiently finely divided by using the shearing force of the pump 5 in addition to the stirring by the second stirrer 4. . As a result, blockage of the pipes 22, 23, and 25 related to transfer can be more effectively prevented, and the boric acid-containing waste liquid used for cement solidification can be stably treated for a long period of time.

(Second Embodiment)
2-5 is a figure which shows schematic structure of the processing apparatus of the boric-acid containing waste liquid in this embodiment. The same reference numerals are used for the same or similar components as those in the processing apparatus shown in FIG.

  As shown in FIGS. 2 to 5, the boric acid-containing waste liquid treatment apparatus of the present embodiment is different from the treatment apparatus of the first embodiment in that a filter is provided on a pipe.

  In the processing apparatus shown in FIG. 2, a pair of filters (lines) 15 are provided on the pipe 22 before and after the pump 5. In the processing apparatus shown in FIG. 2, when the hardly soluble boric acid-containing waste liquid is transferred from the storage tank 3 to the dryer 7 by setting the coarseness of the filter 15 to a predetermined value, for example, 2 mm, the above-mentioned Insoluble borates exceeding the size can be removed. Accordingly, since the boric acid-containing waste liquid to be transferred contains only a relatively small borate having a size smaller than the above-described size, the remaining portion of the pipe 22 and the pipe 23 are caused by such hardly soluble boric acid-containing waste liquid. Can be prevented.

  Moreover, since the size of the borate to be dried and separated by the dryer 7 can be reduced in advance, the size of the residue contained in the washing waste liquid after washing can also be reduced. Therefore, when the cleaning waste liquid is transferred to the storage tank 2, the blockage of the pipe 25 can be suppressed. As a result, blockage of the pipes 22, 23, and 25 related to transfer can be more effectively prevented, and the boric acid-containing waste liquid used for cement solidification can be stably treated for a long period of time.

  FIG. 3 and FIG. 4 show a case where the filter 15 is provided in the pipe 25 in the processing apparatus showing the first and second modifications of the present embodiment. In this case, by setting the coarseness of the filter 15 to a predetermined value, the residue exceeding the above value is removed from the residue contained in the washing waste liquid after washing the dryer 7. Can do. Therefore, since the cleaning waste liquid contains only a residue having a size equal to or smaller than the above value, when the cleaning waste liquid is transferred to the storage tank 3, the remaining portion of the pipe 25 is blocked by the residue. Can be suppressed.

  Moreover, after transferring the residue (including cleaning waste liquid) to the storage tank 3, it is transferred again to the dryer 7 through the pipes 22 and 23 together with the hardly soluble boric acid-containing waste liquid supplied from the pretreatment tank 1. Even in this case, since the size of the residue is equal to or less than the coarseness of the filter 15, blockage of the pipes 22 and 23 due to the residue can be suppressed.

  In the processing apparatus shown in FIG. 3, the filter 15 is provided on the outer side of the storage tank 3 of the pipe 25, whereas in the processing apparatus shown in FIG. 4, the storage tank 3 of the pipe 25 is provided. The filter 15 is provided in the inner part of the. As described above, in the processing apparatus shown in FIGS. 3 and 4, although the position where the filter 15 is provided is slightly different, the filter 15 is provided on the pipe 25 in any case, so that the above-described effects can be obtained. it can.

  In the processing apparatus which shows the 3rd modification of this embodiment in FIG. 5, the filter 15 is provided in the piping 26. FIG. In this case, the boric acid-containing waste liquid in the storage tank 3 is circulated by the pump 5, and in addition to the step of refining the insoluble borate and the residue from the dryer 7 due to the shearing force of the pump 5, the refining is performed. Insufficient borate and residue can be removed by filter 15. Therefore, when the residue is transported from the storage tank 3 to the dryer 7 together with the hardly soluble boric acid-containing waste liquid, and the residue and the insoluble borate are dried and separated, the pipes 22 and 23 related to the transport are transferred. , 25 can be more effectively prevented and the boric acid-containing waste liquid used for cement solidification can be treated stably for a long period of time.

(Third embodiment)
6 and 7 are diagrams showing a schematic configuration of a boric acid-containing waste liquid treatment apparatus according to the present embodiment and its modification. The same reference numerals are used for the same or similar components as those of the processing apparatus shown in FIGS.

  This embodiment corresponds to a modification of the second embodiment. As shown in FIGS. 6 and 7, strainers 16 having a filtering function are provided at the inlet and the outlet of the head tank 6. This is different from the processing apparatus of the second embodiment.

  In the processing apparatus shown in FIG. 6, a strainer 16 is provided at the inlet of the head tank 6, and in the processing apparatus shown in FIG. 7, the strainer 16 is provided at the outlet of the head tank 6. Therefore, by setting the coarseness of the strainer 16 to a predetermined value, when transferring the hardly soluble boric acid-containing waste liquid from the storage tank 3 to the dryer 7, insoluble boron having a size exceeding the above value is transferred. The acid salt can be removed. For this reason, since the boric acid-containing waste liquid to be transferred contains only a relatively fine borate having a size smaller than the above-described size, blockage of the pipe 23 due to such hardly soluble boric acid-containing waste liquid is suppressed. be able to.

  Moreover, since the size of the borate to be dried and separated by the dryer 7 can be reduced in advance, the size of the residue contained in the washing waste liquid after washing can also be reduced. Therefore, when the cleaning waste liquid is transferred to the storage tank 3, the blockage of the pipe 25 can be suppressed. Further, when the residue is transferred from the storage tank 3 to the dryer 7 together with the hardly soluble boric acid-containing waste liquid and dried and separated, blockage of the pipe 22 can be suppressed.

  As a result, blockage of the pipes 22, 23, and 25 related to transfer can be more effectively prevented, and the boric acid-containing waste liquid used for cement solidification can be stably treated for a long period of time.

(Fourth embodiment)
8 and 9 are diagrams showing a schematic configuration of a boric acid-containing waste liquid treatment apparatus according to the present embodiment and its modification. The same reference numerals are used for the same or similar components as those in the processing apparatus shown in FIGS.

  As shown in FIG. 8 and FIG. 9, in the boric acid-containing waste liquid treatment apparatus of the present embodiment, a crushing device 17 is provided in the storage tank 3 and at the tip of the pipe 26. 22 is different from the processing apparatus of the first embodiment in that an inline crushing apparatus 18 is provided on 22.

  In the processing apparatus shown in FIG. 8, the borate and the residue in the hardly soluble boron-containing waste liquid circulated in the storage tank 3 by the pump 5 are pulverized by the pulverizer 17. Therefore, borate and residue sufficiently finely divided by the shearing force by the pump 5 and the pulverization by the pulverizer 17 are introduced into the storage tank 3 and remain. Therefore, when the residue is transferred from the storage tank 3 to the dryer 7 through the pipes 22 and 23 again together with the hardly-solubilized boric acid-containing waste liquid transferred from the pretreatment tank 1 to the storage tank 3, the boric acid is used. Since the salt and the residue are sufficiently finely divided as described above, blockage of the pipes 22 and 23 due to the borate and the residue can be suppressed.

  In addition, since the borate and the residue are sufficiently finely granulated after being transferred into the dryer 7, some of them remain in the dryer 7 without being separated after drying, and the washing water Even after being cleaned in step (1), the pipe 25 is not blocked even when it is transferred to the storage tank 3 via the pipe 25 in a state of being contained in the cleaning waste liquid.

  On the other hand, in the apparatus shown in FIG. 9, when the hardly soluble boric acid-containing waste liquid is transferred from the storage tank 3 to the dryer 7, the insoluble borate is pulverized and refined by the in-line pulverizer 18. . Therefore, since the insoluble borate is sufficiently finely divided by the stirring by the second stirrer 4 provided in the storage tank 3 and the pulverization by the in-line pulverization apparatus 18, the hardly soluble boric acid content is contained. When the waste liquid is transferred through the remaining portion of the pipe 22 and the inside of the pipe 23, the pipes are not blocked.

  Moreover, since the size of the borate to be dried and separated by the dryer 7 can be reduced in advance, the size of the residue contained in the washing waste liquid after washing can also be reduced. Therefore, when the cleaning waste liquid is transferred to the storage tank 3, the blockage of the pipe 25 can be suppressed. As a result, blockage of the pipes 22, 23, and 25 related to transfer can be more effectively prevented, and the boric acid-containing waste liquid used for cement solidification can be stably treated for a long period of time.

In the processing apparatus shown in FIG. 1, 2 L of cleaning waste liquid is introduced into the storage tank 2, the temperature of the waste liquid is set to 60 ° C., the stirring speed of the second stirrer 4 is 500 times / minute, and the stirring power is 0.28 kW / m ³ . Under the condition, an attempt was made to refine the solid content (residue of borate) contained in the washing waste liquid. The results are shown in FIG.

  In FIG. 10, the curve A indicates the abundance ratio of solids having a particle diameter of 5 mm or less, the curve B indicates the abundance ratio of solids having a particle diameter of 5 to 16 mm, and the curve C indicates the abundance ratio of solids having a particle diameter of 16 mm or more. . As is apparent from FIG. 10, the solid content having a particle size of 16 mm and the solid content having a particle size of 5 to 16 mm decrease simultaneously with the start of stirring, and the solid content having a particle size of 16 mm decreases after 35 hours. It can be seen that is almost zero. On the other hand, it can be seen that the abundance ratio of the solid content having a particle size of 5 mm or less increases rapidly at the start of stirring and is close to 100% after 35 hours.

  From these results, it can be seen that coarse solids are sufficiently finely divided by the second stirrer 4.

  Moreover, the particle size distribution of solid content after 62.5 hours passed from the start of stirring was measured. The results are shown in FIG. As is clear from FIG. 11, after 62.5 hours have passed since the start of stirring, the abundance ratio of the particle size of 2.8 mm or less is 100%. From this, too, the second stirrer 4 is coarse. It turns out that solid content is fully refined.

  The present invention has been described in detail based on the above specific examples. However, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

  For example, each of the first to fourth embodiments can be used alone, but two or more embodiments can also be used in combination. For example, it is possible to combine the aspect shown in FIGS. 2, 3 and 5 in the second embodiment with the aspect shown in FIG. 8 in the fourth embodiment to constitute a processing apparatus as shown in FIG. It is. In this case, the processing apparatus shown in FIG. 12 has an operational effect that combines the operational effects of the modes shown in FIGS. 2, 3, and 5 and the mode shown in FIG. 8.

DESCRIPTION OF SYMBOLS 1 Pretreatment tank 2 1st stirrer 3 Storage tank 4 2nd stirrer 5,13 Pump 6 Head tank 7 Dryer 8 Liquid level gauge 9 Flowmeter 10,11 Pressure gauge 12 Washing water tank 15 Filter 16 Strainer 17 Crusher 18 Inline crusher 21, 22, 23, 24, 25, 26, 27 Piping

Claims (17)

A method for treating boric acid-containing waste liquid that solidifies into cement,
In the first tank, the step of making the boric acid-containing waste liquid hardly soluble by precipitating insoluble borate; and
Transporting and storing the hardly soluble boric acid-containing waste liquid in a second tank having a stirrer;
Transferring the hardly-solubilized boric acid-containing waste liquid from the second tank to a dryer, and drying and separating the borate contained in the hardly-solubilized boric acid-containing waste liquid;
Supplying washing water from a washing water tank to wash the dryer, and transferring washing waste liquid containing the borate residue into the second tank;
Refining the borate residue by stirring with the stirrer provided in the second tank;
A method for treating boric acid-containing waste liquid, comprising:   The hardly soluble boric acid-containing waste liquid stored in the second tank is circulated through a pump, and the borate and the borate residue in the hardly soluble boric acid-containing waste liquid are obtained. The boric acid-containing waste liquid treatment method according to claim 1, further comprising a step of finely pulverizing by the shearing force of the pump.   The method for treating a boric acid-containing waste liquid according to claim 1 or 2, wherein the stirring is performed at a rotation speed of 500 times / minute or more. The method for treating boric acid-containing waste liquid according to any one of claims 1 to 3, wherein the stirring power of the stirring is 0.28 kW / m ³ or more.   In order to maintain the stirring power, the method includes a step of raising and lowering the stirrer according to the level of the hardly soluble boric acid-containing waste liquid stored in the second tank. The processing method of the boric-acid containing waste liquid of Claim 4.   The pulverizer is provided in the second tank, and the pulverizer is used to fine-tune the borate and the borate residue in the hardly soluble boric acid-containing waste liquid stored in the second tank. 6. A method for treating a boric acid-containing waste liquid according to any one of claims 1 to 5, further comprising the step of:   An additional crushing device is provided between the second tank and the dryer, and the step of refining the borate in the hardly soluble boric acid-containing waste liquid stored in the second tank is performed. The processing method of the boric acid containing waste liquid as described in any one of Claims 1-6 characterized by the above-mentioned.   8. The step of filtering the hardly soluble boric acid-containing waste liquid when transferring the hardly soluble boric acid containing waste liquid from the second tank to the dryer. The processing method of the boric acid containing waste liquid as described in any one of these.   9. The method according to claim 1, further comprising a step of filtering the cleaning waste liquid when the cleaning waste liquid containing the borate is transferred into the second tank. Treatment method of boric acid-containing waste liquid.   When the hardly-solubilized boric acid-containing waste liquid stored in the second tank is circulated through the pump, it comprises a step of filtering the hardly-solubilized boric acid-containing waste liquid. The processing method of the boric-acid containing waste liquid as described in any one of Claims 2-9. An apparatus for treating boric acid-containing waste liquid that solidifies cement,
A first tank for making the boric acid-containing waste liquid hardly soluble by precipitating insoluble borate;
A second tank having a stirrer for storing the hardly-solubilized boric acid-containing waste liquid transferred from the first tank;
A drier for drying and separating the borate contained in the hardly soluble boric acid-containing waste liquid transferred from the second tank;
A washing water tank for supplying washing water to the dryer for washing,
The cleaning waste liquid containing the borate residue is transferred into the second tank, and the borate residue is refined by stirring with the stirrer provided in the second tank. An apparatus for treating boric acid-containing waste liquid, characterized in that it is configured as follows.   A pump for circulating the hardly soluble boric acid-containing waste liquid stored in the second tank; and the borate and the borate residue in the hardly soluble boric acid-containing waste liquid, 12. The boric acid-containing waste liquid treatment apparatus according to claim 11, wherein the boric acid-containing waste liquid treatment apparatus is configured to be finely divided by a shearing force of the pump.   In order to maintain the stirring power, it comprises a mechanism for raising and lowering the stirrer according to the level of the hardly soluble boric acid-containing waste liquid stored in the second tank. The boric acid containing waste liquid processing apparatus according to claim 11 or 12.   The said 2nd tank has a crushing apparatus for pulverizing the said borate and the residue of the said borate in the said hardly soluble boric acid containing waste liquid stored, The characterized by the above-mentioned. The processing apparatus of the boric acid containing waste liquid as described in any one of 11-13.   Between the second tank and the dryer, further comprising an additional pulverization device for finely pulverizing the borate in the sparingly soluble boric acid-containing waste liquid stored, The processing apparatus of the boric acid containing waste liquid as described in any one of Claims 11-14.   The boric acid-containing waste liquid according to any one of claims 11 to 15, further comprising a filter for the hardly-solubilized boric acid-containing waste liquid between the second tank and the dryer. Processing equipment.   An additional filter for the hardly soluble boric acid-containing waste liquid stored in the second tank is disposed in a circulation line of the second tank including the pump. The processing apparatus of the boric-acid containing waste liquid as described in any one of 16.

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