JP2014210235A - Method and apparatus for regenerating acid for cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate an acid, when the acid has been used for cleaning and contains a metal component in a relatively large amount, by removing a metal component from the acid after use and, at the same time, concentrating the acid.SOLUTION: A method for regenerating an acid for cleaning includes the steps of: subjecting an object to be cleaned to acid cleaning by supplying an acid for cleaning into a cleaning tank; performing solid-liquid separation of a solid content contained in a first solution obtained by the acid cleaning, in a solid-liquid separation tank; and adsorbing and removing a first metal component contained in a second solution obtained by the solid-liquid separation by an adsorption tower having an adsorption material provided inside. Further, the method includes a step comprising: removing a second metal component contained in a third solution, obtained by the adsorbing and removing, by using an electrodialysis tank in which a plurality of cation exchange membranes capable of passing only hydrogen ions by ion exchange and a plurality of anion-exchange membranes are alternately disposed and an anode and a cathode are disposed on both sides of the membranes; and concentrating the acid contained in the third solution until the concentration of the acid becomes equal to a concentration of the acid for cleaning.

Description

  Embodiments described herein relate generally to a cleaning acid regeneration method and an apparatus therefor.

  Research has been conducted on acid regeneration technology used in cleaning processes in various industrial processes.

  For example, in washing processes in various industrial processes, inorganic acids such as hydrochloric acid, sulfuric acid, and hydrofluoric acid, and organic acids such as citric acid and oxalic acid are used. The waste acid after being used in these applications is generally neutralized and disposed of, but it is desired to be recycled because it has a large environmental load. As an example, a process of removing radioactive cesium from acid from sewage sludge incineration ash with high-concentration radioactive contamination is known, and acid recycling in the process is also recognized as an important technology from the viewpoint of environmental burden.

  When regenerating the acid after use in the washing step, for example, the acid is adsorbed on the anion exchange resin (substance), and then the acid is removed from the anion exchange resin using an alkaline aqueous solution or an organic solvent. There is a method in which a concentrated acid is obtained and regenerated by elution and subjecting the resulting solution to a treatment such as distillation or membrane separation.

  However, in the acid regeneration method as described above, a large amount of alkaline aqueous solution or the like is required to separate the organic acid from the anion exchange resin, and distillation or the like is performed to concentrate the separated organic acid. Many processes are required. Therefore, there is a drawback that it takes much cost to separate and recover the concentrated and regenerated acid from the anion exchange resin.

  In view of such a problem, Patent Document 1 discloses that a substance adsorbing an organic acid and containing moisture (anion exchange resin) is brought into contact with carbon dioxide having a pressure of 1 MPa or more and a temperature of 20 ° C. or more. A technique is disclosed in which the organic acid is transferred to the carbon dioxide and separated and regenerated from the substance.

  However, when the acid after washing contains a relatively large amount of metal component, a relatively large amount of metal component that is not initially included in the concentrated acid even if the acid is concentrated by the method described above. Will be included. Therefore, even if the above-described cleaning process is performed again using such concentrated acid, the initial cleaning process cannot be performed due to a relatively large amount of metal components contained in the acid. There were problems such as contaminating the object to be acid cleaned.

JP 2004-089904 A

  An object of the present invention is to regenerate the acid by removing the metal component from the used acid and concentrating the acid when the washed acid contains a relatively large amount of the metal component.

  The cleaning acid regeneration method of the embodiment is obtained by supplying the cleaning acid into the cleaning tank, performing the acid cleaning on the object to be cleaned, and obtaining the first solution, and the acid cleaning. The solid content included in the first solution is subjected to solid-liquid separation in a solid-liquid separation tank to obtain a second solution. A third step of obtaining a third solution by adsorbing and removing the first metal component contained in the second solution obtained by the solid-liquid separation by an adsorption tower provided with an adsorbent; A plurality of cation exchange membranes and a plurality of anion exchange membranes that allow only hydrogen ions to permeate through the second metal component contained in the third solution obtained by adsorption removal are alternately arranged, and Fourth, the acid is removed by an electrodialysis tank provided with an anode and a cathode on both sides, and the acid contained in the third solution is concentrated to concentrate the acid concentration to the concentration of the cleaning acid. With steps.

It is a figure which shows schematic structure of the reproduction | regeneration apparatus of the acid for washing | cleaning in 1st Embodiment. It is a figure which shows schematic structure of the electrodialysis tank in the reproduction | regeneration apparatus of the acid for washing | cleaning shown in FIG. It is a figure which shows schematic structure of the reproduction | regeneration apparatus of the acid for washing | cleaning in 2nd Embodiment.

(First embodiment)
First, the cleaning acid regenerating apparatus used in this embodiment will be described. FIG. 1 is a diagram showing a schematic configuration of a cleaning acid regenerating apparatus used in the present embodiment. Moreover, FIG. 2 is a figure which shows schematic structure of the electrodialysis tank in the acid reproduction | regeneration apparatus shown in FIG.

  An acid regenerator 10 shown in FIG. 1 includes a washing tank 11 for performing acid washing, a solid-liquid separation tank 21 for separating the metal component washed in the washing tank 11 into a solid-liquid separation, and Located on the downstream side, an adsorption tower 31 provided with an adsorbent 32 that can be treated at a low pH (for example, pH 2 or less) such as a strongly acidic cation exchange resin and a chelate resin, and located on the downstream side of the adsorption tower 31 And an electrodialysis tank 41.

  A heating mechanism 12 is disposed in the cleaning tank 11, and an acid storage tank 13 that supplies an acid for performing a cleaning process in the cleaning tank 11 is disposed above the cleaning tank 11. In the cleaning tank 11, a pH measuring device 14 for measuring the pH of the solution in the cleaning process in the cleaning tank 11 and a thermometer 15 for measuring the temperature are arranged.

  The pH measuring device 14 is connected to the pH control unit 16, and the pH control unit 16 adjusts the opening degree of the valve 18 disposed in the acid storage tank 13 based on the pH value measured by the pH measuring device 14. In addition, the amount of acid supplied from the acid storage tank 13 into the cleaning tank 11 can be adjusted. The thermometer 15 is connected to the temperature control unit 17, and controls the heating mechanism 12 connected to the temperature control unit 17 based on the temperature measured by the thermometer 15, so that The temperature of the solution in the cleaning process is controlled so that the cleaning process is performed efficiently and effectively.

  A rectifying wall 22 for rectifying the solution supplied from the cleaning tank 11 is provided in the solid-liquid separation tank 21 so as to extend from the top of the solid-liquid separation tank 21 to near the bottom.

  In the electrodialysis tank 41, a desalted water tank 42 is provided via pipes 44 and 46 and a pump 48, and a concentrated water tank 43 is provided via pipes 45 and 47 and a pump 49.

  As will be described in detail below, the demineralized water tank 42 functions as a tank for introducing an acid solution in the process of treatment to the electrodialysis tank 41, and is connected to the desalting chamber of the electrodialysis tank 41. The washed acid solution introduced into the electrodialysis tank 41 through the pipes 44 and 46 and the pump 48 is circulated in the desalting chamber. The concentrated water tank 43 functions as a tank for removing the concentrated acid from the electrodialysis tank 41 and is connected to the concentration chamber of the electrodialysis tank 41. The washed acid solution introduced into the electrodialysis tank 41 via 47 and the pump 49 is circulated in the concentration chamber.

  The concentrated water tank 43 is previously filled with an acid solution containing a low concentration of water or the same acid as the cleaning acid, and hydrogen ions and anions constituting the acid confined in the concentrated tank of the electrodialysis tank 41. However, it can circulate in the state dissolved in the acid solution. On the other hand, since the acid solution after washing is introduced into the desalting chamber, it is not necessary to fill water or the like in advance like the concentrated water tank 43.

  In the electrodialysis tank 41, as shown in FIG. 2, a cation exchange membrane 411 and two anion exchange membranes 412 that allow only two hydrogen ions to pass through ion exchange are alternately arranged on both sides thereof. An anode 413 and a cathode 414 are disposed, and the anode 413 and the cathode 414 are connected to a power source V. In addition, when the electrodialysis tank 41 employs the above-described configuration, two concentration tanks 41A are formed, and one desalting chamber 41B is formed between the two concentration tanks 41A.

  In addition, the cation exchange membrane 411 which permeate | transmits only a hydrogen ion by ion exchange can be comprised from a general purpose, for example, can be comprised from commercially available things, such as HSF (made by Asahi Glass Co., Ltd.).

  Similarly, the anion exchange membrane 412 can be made of a general-purpose material, for example, a commercially available material such as AMV (Asahi Glass Co., Ltd.).

  In the electrodialysis tank 41 of the cleaning acid regeneration apparatus 10 in this embodiment, as described above, the two concentration tanks 41A are formed. Therefore, the pipes 45 and 47 are appropriately branched, and the above-described 2 of the electrodialysis tank 41. The two concentrating tanks 41A are connected to circulate in the two concentrating chambers 41A.

  Further, in the present embodiment, two cation exchange membranes 411 and two anion exchange membranes 422 are alternately arranged in the electrodialysis tank 41, but the number of these ion exchange membranes is arbitrary as required. Can be set to

  Next, a cleaning acid regeneration method using the cleaning acid regeneration apparatus 10 shown in FIG. 1 will be described.

  First, the cleaning object S1 is introduced into the cleaning tank 11 as indicated by an arrow in the figure, and a predetermined acid is supplied from the acid storage tank 13 into the cleaning tank 11 to be cleaned in the cleaning tank 11. The object S1 is washed with an acid. Examples of the cleaning object S1 include semiconductor wafers, metal materials, soil containing radioactive materials such as radioactive cesium, sewage sludge incineration ash, fly ash, and the like. Cleaning of the semiconductor wafer or the like is performed for etching treatment, removal of scale and rust, and removal of the acid film. Washing of soil containing radioactive substances is performed for removing radioactive substances contained in the soil or the like, for example, radioactive cesium.

  In addition, as said acid, organic acids, such as a citric acid and an oxalic acid other than inorganic acids, such as hydrochloric acid, a sulfuric acid, and nitric acid, can be used. The pH of the acid is not particularly limited as long as the cleaning object S1 can be cleaned as described above, but can be set to, for example, 2.0 or less, preferably 1.3 or less, and particularly preferably pH 1.2 or less.

  The type of the metal component depends on the object to be cleaned S1, and examples include light metals such as aluminum, manganese, calcium, and magnesium, and heavy metals such as iron, zinc, and lead.

  In the cleaning process of the cleaning object S1, the acid supplied from the acid storage tank 13 dissolves the dissolved material and the cleaned metal component of the cleaning object S1, and the cleaning object S1 can be stably cleaned. Since it may disappear, it is preferable to measure the pH value in the washing tank 11 with the pH measuring device 14 as appropriate. As described above, since the pH measuring device 14 is connected to the pH control unit 16, when the pH value of the solution in the cleaning tank 11 decreases, the pH control unit 16 distributes it to the acid storage tank 13. The opening degree of the provided valve 18 is increased, and the amount of acid supplied into the cleaning tank 11 is increased.

  The solution in the cleaning process in the cleaning tank 11 is preferably heated by the heating device 12 to a predetermined temperature, for example, 80 to 95 ° C. Thereby, the cleaning of the cleaning object S1 in the cleaning tank 11 can be promoted. The temperature of the solution is measured by the thermometer 15. As described above, since the thermometer 15 is connected to the temperature control unit 17, the temperature control unit 17 appropriately monitors the temperature of the solution, and When the temperature is outside the set temperature range, a temperature control unit 17 appropriately transmits a control signal to the heating mechanism 12 to appropriately control the degree of heating of the solution by the heating mechanism 12.

  In addition, the time regarding the washing | cleaning in the washing tank 11 can be 10 to 30 minutes, for example.

  Next, the solution L1 obtained in the washing tank 11 is introduced into the solid-liquid separation tank 21 as indicated by an arrow in the figure, and the solid content S2 resulting from the above-described dissolved matter in the solution L1 is subjected to solid-liquid separation. To remove. In this embodiment, as shown in FIG. 1, solid content S2 is precipitated at the bottom of the solid-liquid separation tank 21 by the coagulation sedimentation method, and solid-liquid separation is performed. Solid-liquid separation can also be performed by a method such as centrifugation.

  As described above, since the rectifying wall 22 is provided in the solid-liquid separation tank 21, the solution L1 is rectified when the solution L1 is introduced into the solid-liquid separation tank 21, so that the solid content S2 The aggregation and precipitation in the solid-liquid separation tank 21 is not hindered.

  Next, the solution L2 after removal of the solid content S2 obtained in the solid-liquid separation tank 21 is introduced into the adsorption tower 31 as indicated by an arrow in the figure. In the adsorption tower 31, the solution L2 is acidic, in particular, acidic at pH 2 or lower due to the acid used in the washing tank 11, so that a strong acidic cation exchange resin, a chelate resin, etc. are contained therein as described above. The adsorbent 31 can be processed at a low pH (for example, pH 2 or lower). Therefore, as shown by the arrow in the figure, the solution L2 is passed through the adsorption tower 31 to adsorb and remove the metal component (metal ion) washed in the washing tank 11 contained in the solution L2.

  In the adsorption tower 31, when a strongly acidic ion exchange resin is used, light metals such as aluminum, manganese, calcium, and magnesium are mainly removed. Further, when a chelate resin is used, heavy metals such as iron, zinc and lead are mainly removed. However, when removing radioactive substances, particularly radioactive cesium, from soil, sewage sludge incineration ash, fly ash, the zeolite is radioactively adsorbed by a tower filled with zeolite such as mordenite zeolite (not shown) in front of the adsorption tower 31. Adsorbs and removes cesium.

  Next, the solution L2 obtained in the adsorption tower 31 is introduced into the electrodialysis tank 41 as indicated by an arrow in the figure. Specifically, it is introduced into a demineralized water tank 42 disposed close to the electrodialysis tank 41.

  On the other hand, in the electrodialysis tank 41, electrodialysis is performed by supplying a direct current or a direct voltage via the power source V between the anode 413 and the cathode 414 located on both sides. In the solution L2, the acid exists in the form of hydrogen ions and anions, and the metal component exists mainly in the form of cations.

  In this embodiment, the cation exchange membrane 411 transmits only hydrogen ions by ion exchange, does not transmit anions and metal ions, and the anion exchange membrane 412 transmits only the anions by ion exchange. In the concentration tank 41A, hydrogen ions and anions constituting the acid are confined, whereby the acid is concentrated. On the other hand, the metal component is ion-exchanged by the cation exchange membrane 511 and is confined in the desalting chamber 41B.

  Further, in the present embodiment, a desalting water tank 42 is connected to the desalting chamber 41B of the electrodialysis tank 41 via pipes 44 and 46 and a pump 48, and the inside of the desalting chamber 41B is circulated along with electrodialysis. The metal component (metal ions) concentrated in the desalting chamber 41B is appropriately taken out from the desalting chamber and stored. Further, the concentrated water tank 43 is connected to the concentration chamber 41A of the electrodialysis tank 41 via the pipes 45, 47 and the pump 49, and the acid concentrated in the concentration chamber 41A is circulated through the concentration chamber 41A. It is taken out from the concentration tank 41A as appropriate and stored.

  Here, when a pH measuring device (not shown) is connected to the concentration chamber 41A so that the pH value of the concentration chamber 41A can be measured, the pH value of the acid in the concentration chamber 41A is set to a target pH value, for example, a washing tank. When the pH value of the acid in the acid storage tank 13 for storing the acid to be supplied to 11 is reached, the electrodialysis process is terminated. Since the acid adjusted as described above has the initial pH value of the acid, it can be reused in the cleaning process in the cleaning tank 21 by returning to the acid storage tank 13.

  In the electrodialysis tank 41, components that could not be removed by the adsorption tower 31 are removed from the solution L2. When a strongly acidic cation exchange resin is used in the adsorption tower 31, heavy metals such as iron, zinc and lead are mainly removed. Further, when a chelate resin is used, heavy metals such as iron, zinc and lead are mainly removed. Further, when zeolite is used, radioactive cesium is removed.

(Second Embodiment)
First, the cleaning acid regenerating apparatus used in this embodiment will be described. FIG. 3 is a diagram showing a schematic configuration of a cleaning acid regenerator used in the present embodiment.

  As is clear from FIG. 3, the cleaning acid regenerating apparatus 70 of the present embodiment has an acid capacity adjusting tank 51 disposed downstream of the electrodialysis tank 41 in the cleaning acid regenerating apparatus 10 shown in FIG. It differs in that it is provided, and the other configurations are the same. Therefore, in the following, the difference, that is, the advantage of the cleaning acid regenerating apparatus 70 by providing the acid capacity adjusting tank 51 will be described.

  Other configurations, functions, and operational effects are the same as those in the first embodiment related to the cleaning acid regenerator 10 shown in FIG.

  As shown in FIG. 3, an additional acid storage tank 53 is disposed above the acid capacity adjustment tank 51, and a capacity control unit 56 is disposed. The capacity control unit 56 adjusts the opening degree of the valve 58 provided in the additional acid storage tank 53 according to the capacity of the acid stored in the acid storage tank 13, and the acid from the additional acid storage tank 53. The amount of acid supplied into the capacity adjustment tank 51 can be adjusted.

  Next, a cleaning acid regeneration method using the cleaning acid regeneration apparatus 70 shown in FIG. 3 will be described.

  First, as described in the first embodiment, the cleaning object S1 is introduced into the cleaning tank 11, and a predetermined acid is supplied from the acid storage tank 13 into the cleaning tank 11. After the cleaning object S1 is washed with an acid, the solution L1 obtained in the washing tank 11 is introduced into the solid-liquid separation tank 21, and the solid content S2 caused by the dissolved matter in the solution L1 is solid-liquid separated. And remove.

  Next, when the solution L2 after removal of the solid content S2 obtained in the solid-liquid separation tank 21 is introduced into the adsorption tower 31 and a strong acidic ion exchange resin is used in the adsorption tower 31, mainly aluminum, manganese, calcium, magnesium, etc. In the case of using a chelate resin, mainly heavy metals such as iron, zinc and lead are removed. However, when removing radioactive substances, particularly radioactive cesium, from soil, sewage sludge incineration ash, fly ash, the zeolite is radioactively adsorbed by a tower filled with zeolite such as mordenite zeolite (not shown) in front of the adsorption tower 31. Adsorbs and removes cesium.

  The acid concentrate L4 thus obtained has an initial acid pH value, that is, the same pH value as the acid stored in the acid storage tank 13, but the capacity of the acid concentrate L4 is in the acid storage tank 13. Reduced compared to the volume of acid stored. This is because, for example, when the solid content S2 is agglomerated and precipitated in the solid-liquid separation tank 21, the acid is contained in the solid content S2 in a certain ratio, and further, the adsorption provided in the adsorption tower 31. This is because the material 32 is adsorbed and absorbed at a certain rate.

  Therefore, in this embodiment, the acid concentrate L4 is transferred from the concentrated water tank 43 to the acid capacity adjusting tank 51. Here, additional acid is added from the additional acid storage tank 53 to the acid concentrate L4 in the acid capacity adjustment tank 51, and the amount of acid present in the acid capacity adjustment tank 51 is stored in the acid storage tank 13. Equal to the acid capacity. In addition, since the capacity | capacitance of the acid stored in the acid storage tank 13 is previously memorize | stored in the capacity | capacitance control part 56, it is a valve | bulb from the capacity | capacitance control part 56 according to the capacity | capacitance of the acid which should be added to the acid concentrate L4. A control signal is transmitted to 58, the opening degree of the valve 58 is adjusted, and the amount of acid added from the additional acid storage tank 63 into the acid capacity adjustment tank 51 is adjusted as appropriate.

  The acid adjusted as described above has an initial acid pH value and is adjusted to the same capacity as the acid stored in the acid storage tank 13, so it can be returned directly to the cleaning tank 21, Initially, the acid supplied to the washing tank 11 can be recycled by circulating through the regenerator 70 shown in FIG.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10, 70 Cleaning-acid regeneration apparatus 11 Cleaning tank 12 Heating mechanism 13 Acid storage tank 14 pH measuring device 15 Thermometer 16 pH control part 17 Temperature control part 18 Valve 21 Solid-liquid separation tank 22 Rectification wall 31 Adsorption tower 32 Adsorbent 41 Electrodialysis tank 42 Demineralized water tank 43 Concentrated water tank 51 pH adjustment tank 53 Additional acid storage tank 56 Volume control unit 58 Valve S1 Object to be cleaned S2 Solid content L1, L2, L3 solution L4 Acid concentrate

Claims (10)

A first step of supplying a cleaning acid into the cleaning tank, performing an acid cleaning on the object to be cleaned, and obtaining a first solution;
A second step of obtaining a second solution by solid-liquid separation of a solid content contained in the first solution obtained by the acid washing in a solid-liquid separation tank;
A third step of obtaining a third solution by adsorbing and removing the first metal component contained in the second solution obtained by the solid-liquid separation by an adsorption tower having an adsorbent therein;
A plurality of cation exchange membranes and a plurality of anion exchange membranes that allow only the hydrogen ions to permeate through the second metal component contained in the third solution obtained by the adsorption removal are alternately disposed, First, the acid is removed by an electrodialysis tank provided with an anode and a cathode on both sides, and the acid contained in the third solution is concentrated to concentrate the acid concentration to the cleaning acid concentration. 4 steps,
A method for regenerating a cleaning acid, comprising:   The method further comprises a fifth step of adjusting the volume of the acid to the volume of the cleaning acid in a volume adjustment tank after the acid contained in the third solution is concentrated. Item 2. A method for regenerating a cleaning acid according to Item 1.   In the first step, the pH value of the cleaning acid in the cleaning tank is measured with a pH meter, and the amount of the cleaning acid supplied to the cleaning tank is adjusted according to the pH value. The method for regenerating a cleaning acid according to claim 1, wherein the cleaning acid is regenerated.   The method for regenerating a cleaning acid according to any one of claims 1 to 3, wherein the adsorbent is at least one of a strongly acidic cation exchange resin and a chelate resin. The cleaning object is a waste containing radioactive cesium,
The said radioactive cesium includes the 5th step adsorb | sucking with the zeolite with which it filled in the additional tower arrange | positioned upstream of the said adsorption tower, The any one of Claims 1-4 characterized by the above-mentioned. A method for regenerating a cleaning acid as described. A cleaning tank for supplying a cleaning acid, performing an acid cleaning on an object to be cleaned, and obtaining a first solution;
A solid-liquid separation tank for solid-liquid separation of the solid content contained in the first solution obtained by the acid washing, and obtaining a second solution;
An adsorption tower for adsorbing and removing the first metal component contained in the second solution obtained by the solid-liquid separation and obtaining a third solution;
While removing the 2nd metal component contained in the 3rd solution obtained by the said adsorption removal, the acid contained in the said 3rd solution is concentrated, and the density | concentration of the said acid is set to the density | concentration of the said washing | cleaning acid An electrodialysis tank in which a plurality of cation exchange membranes and a plurality of anion exchange membranes that allow only hydrogen ions to permeate through ion exchange are alternately disposed, and an anode and a cathode are disposed on both sides thereof,
An apparatus for regenerating cleaning acid, comprising:   The cleaning according to claim 6, further comprising a capacity adjustment tank that adjusts the capacity of the acid to the capacity of the cleaning acid after the acid contained in the third solution is concentrated. Acid regenerator.   A pH measuring device is provided for measuring a pH value of the cleaning acid in the cleaning tank and adjusting an amount of the cleaning acid supplied to the cleaning tank according to the pH value. Item 8. The apparatus for regenerating cleaning acid according to Item 6 or 7.   9. The cleaning acid regenerating apparatus according to claim 6, wherein the adsorbent is at least one of a strongly acidic cation exchange resin and a chelate resin. The cleaning object is a waste containing radioactive cesium,
The cleaning acid according to any one of claims 6 to 9, further comprising an additional tower disposed upstream of the adsorption tower and filled with zeolite that adsorbs the radioactive cesium. Playback device.

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