JP2012149168A - Method of treating waste ion exchange resin containing chromium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of hexavalent chromium contained in a combustion residue by a simple method when a waste ion exchange resin having a relatively large amount of chromium adsorbed thereon or contained therein is burnt and then solidified with cement especially at a nuclear facility.SOLUTION: A method of treating the waste ion exchange resin containing the chromium includes: a step of carbonizing the waste ion exchange resin; and a step of solidifying with the cement, a residue generated after the carbonization.

Description

  Embodiments described herein relate generally to a processing method and a processing apparatus for waste ion exchange resin containing chromium.

  Chromium ions are contained as a rust preventive in cooling water used in nuclear facilities such as nuclear power plants and thermal power plants. On the other hand, in nuclear power plants, waste ion exchange resins that have been used after purifying condensate and waste liquid are solidified with a solidifying material such as cement. However, when the ion-exchange resin treated with the chromium-containing rust preventive agent is cement-solidified, chromium and harmful hexavalent chromium are eluted from the cement-solidified body. In particular, hexavalent chromium has an elution standard, and it is necessary to reduce the elution amount as much as possible.

  Further, in the cement solidification method, since the waste ion exchange resin mixing rate in the cement solidified body is about 10%, the amount of the cement solidified body used is increased, and there is a problem that volume reduction is low. Therefore, recently, a method for solidifying cement from the generated incinerated ash after incineration of waste ion exchange resin together with combustible waste has been studied. However, the chromium adsorbed on the waste ion exchange resin is oxidized to hexavalent chromium during the incineration treatment in the air atmosphere, which may increase the amount of hexavalent chromium.

  Patent Document 1 contains chromium that includes a fluidized bed furnace body, a waste heat boiler that recovers the heat of the combustion exhaust gas from the fluidized bed body, and a purification treatment device that purifies the combustion exhaust gas from the waste heat boiler. In a fluidized bed combustor using organic matter as fuel, hexavalent chromium contained in the combustion residue obtained by burning organic matter as fuel is converted (reduced) into trivalent chromium by heating in a reducing atmosphere. Technology is disclosed. Examples of the organic matter include bagasse and waste wood, which are intended for reduction treatment of chromium contained in a very small amount (ppm order) in naturally occurring organic matter.

  In Patent Document 2, sludge or lump containing hexavalent chromium is mixed with fuel such as waste plastic and sawdust and mixed and burned in a rotary kiln to reduce hexavalent chromium to trivalent chromium. A method is disclosed. In addition, since the said sludge and lump are intended for general industrial waste etc., they are intended for reduction treatment of chromium contained in a very small amount (ppm order).

  However, none of the above-mentioned techniques makes any mention of the treatment of waste ion exchange resins containing a relatively large amount of chromium discharged from nuclear facilities (for example, on the order of several percent with respect to waste ion exchange resins). .

JP 2008-275176 A JP 2005-224802 A

  The present invention reduces the amount of hexavalent chromium contained in the combustion residue by a simple method, especially when a waste ion exchange resin that adsorbs and contains a relatively large amount of chromium is burnt and solidified in a nuclear facility. The task is to do.

  One aspect of the present invention is a method for treating a waste ion exchange resin containing chromium, the method comprising: carbonizing the waste ion exchange resin; and cementing the residue after carbonization. It is related with the processing method of the waste ion exchange resin containing chromium characterized by the above-mentioned.

  According to the present invention, particularly in a nuclear facility, when a waste ion exchange resin that adsorbs and contains a relatively large amount of chromium is combusted to solidify the cement, the amount of hexavalent chromium contained in the combustion residue by a simple method. Can be reduced.

It is a schematic block diagram which shows the processing apparatus of the waste ion exchange resin containing chromium of embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a processing apparatus for waste ion exchange resin containing chromium in the present embodiment. A waste ion exchange resin treatment apparatus 10 shown in FIG. 1 includes a carbonization apparatus 10 for carbonizing a waste ion exchange resin containing chromium, and a solidified body preparation apparatus 40 for solidifying a residue after the carbonization treatment. ing.

  The carbonization apparatus 10 includes a carbonization chamber 21 in which waste ion exchange resin containing chromium to be processed is placed, and also includes a heating burner 23. The heating burner 23 burns a gas mixture of air or air and dry distillation gas supplied from the blower 24 and hydrocarbon gas such as propane gas supplied from the hydrocarbon gas supply device 25, thereby causing the inside of the carbonization chamber 21 to burn. The waste ion exchange resin put in the container is heated so that carbonization can be performed.

  As is clear from FIG. 1, the carbonization chamber 21 is disposed in the heating furnace 22, and the heating burner 23 is fixed to the wall surface of the heating furnace 22. The blower 24 is connected to the heating furnace 22 via a pipe 31, and the hydrocarbon gas supply device 25 is connected to the heating furnace 22 via a pipe 32.

  The carbonization chamber 21 is provided with an oxygen concentration meter 26 and a thermocouple thermometer 27 so that the oxygen concentration in the carbonization chamber 21 and the combustion temperature during the carbonization treatment can be appropriately monitored. .

  Further, the blower 24 is connected to the carbonization chamber 21 via a pipe 33 and a pipe 34, and the oxygen concentration measured by the oxygen concentration meter 26 and / or the thermocouple thermometer 27 disposed in the carbonization chamber 21 and Air or air supplied by the blower 24 or air and dry distillation gas is appropriately introduced into the carbonization chamber 21 by controlling the opening / closing of the oxygen concentration adjusting valve 28 provided in the pipe 33 according to the combustion temperature during carbonization. The internal oxygen concentration can be adjusted. This open / close control is controlled by an open / close value of the oxygen concentration adjusting valve 28 determined in advance from the relationship between the properties of air or an introduced gas such as air and dry distillation gas and the oxygen concentration and / or combustion temperature during carbonization. Shall.

  A pipe 37 is connected to the lower portion of the carbonization chamber 21 so that the carbonized residue can be supplied to the solidified body manufacturing apparatus 40 so that cement can be appropriately solidified.

  In the present embodiment, the carbonization apparatus 10 and the solidified body preparation apparatus 40 are connected via a pipe 37, and as described below, carbonization treatment and cement solidification treatment of the chromium-containing waste ion exchange resin are continuously performed. However, it is also possible to separate the carbonization apparatus 10 and the solidified body production apparatus 40 from each other and perform them in a batch mode.

  Next, the processing method of the waste ion exchange resin containing chromium using the processing apparatus 10 shown in FIG. 1 will be described.

  First, an ion exchange resin that adsorbs and contains chromium, which is used in a nuclear facility, for example, is placed in the carbonization chamber 21 in the processing apparatus 10 of FIG. Chromium is derived, for example, from chromium ions as a rust preventive agent in the cooling water used in the nuclear facilities and the like.

  The waste ion exchange resin is granulated in advance using a predetermined resin composition into pellets or particles, and the obtained pellet or particle waste ion exchange resin is carbonized in the same manner as described above. Can be put inside. By making the waste ion exchange resin into pellets or particles, it becomes possible to uniformly heat the waste ion exchange resin by the carbonization treatment described below, so that a uniform carbonization treatment can be performed.

  Further, when the waste ion exchange resin contains a weakly basic ion exchange resin, the waste ion exchange resin contains an amino group, so that in the state as it is, the amino group is liberated to generate amine gas or react with air. In some cases, ammonia gas may be generated. However, as will be described below, in the present embodiment, the waste ion exchange resin is carbonized in a reducing atmosphere, so that the formation of the reducing atmosphere is obstructed even if the above gas is generated. is not.

  However, if the amine gas or ammonia gas as described above is generated, it becomes difficult to control the heating operation by combustion of hydrocarbon gas or the like, and the control of carbonization treatment becomes difficult. Before carbonization, the substrate is immersed in an alkaline aqueous solution placed in a reaction vessel (not shown). Then, the waste ion exchange resin, that is, the amino group of the weakly basic ion exchange resin contained therein is decomposed by the alkali in the alkaline aqueous solution. For example, when sodium hydroxide is used, the amino group is decomposed to become amine or ammonia and released out of the system. Therefore, even when it is subsequently subjected to carbonization treatment, amine gas and ammonia gas are not generated, so the above disadvantages can be eliminated.

  The aqueous alkali solution preferably contains a monovalent alkali. Since monovalent alkali is a strong base, the amino group can be decomposed more efficiently. That is, the amino group can be decomposed in a shorter time. Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like, and sodium hydroxide is particularly preferable.

  In this case, the content of monovalent alkali in the aqueous alkali solution is preferably 25% by mass to 38% by mass. Thereby, the amino group of the waste ion exchange resin can be decomposed more efficiently. When the monovalent alkali content is less than 25% by mass, the efficiency of amino group decomposition by alkali may not be sufficiently improved. On the other hand, even if the monovalent alkali content exceeds 38% by mass, the decomposition efficiency of amino groups can no longer be improved, and the reaction vessel may be corroded.

  Moreover, it is preferable that the temperature of aqueous alkali solution is the range of 90 to 100 degreeC. Also in this case, the amino group of the waste ion exchange resin can be decomposed more efficiently. If the temperature of the aqueous alkali solution is less than 90 ° C., the efficiency of amino group decomposition by alkali may not be sufficiently obtained. On the other hand, when the temperature of the alkaline aqueous solution exceeds 100 ° C., the reaction vessel may be corroded.

  Next, the inside of the carbonization chamber 21 is made a reducing atmosphere. In this case, the inside of the carbonization chamber 21 can be made a reducing atmosphere by exhausting the inside of the carbonization chamber 21 with a pump or the like (not shown) and reducing the amount of oxygen remaining in the carbonization chamber 21. Further, the inside of the carbonization chamber 21 can be made a reducing atmosphere by introducing a reducing gas such as nitrogen gas or ammonia gas. In this case, an inert gas such as nitrogen gas can be appropriately introduced in addition to the reducing gas. From the viewpoint of reducing hexavalent chromium in the residue after the carbonization treatment, it is preferable to positively introduce a reducing gas into the carbonization chamber 21 as in the latter case.

  Further, as a preferable reducing atmosphere, the oxygen concentration is 1% by volume or less. In this case, the carbonization treatment of the waste ion exchange resin containing chromium introduced into the carbonization chamber 21 can be performed more completely, and the amount of hexavalent chromium in the carbonization residue can be sufficiently reduced.

  The oxygen concentration in the carbonization chamber 21 is appropriately measured by an oxygen concentration meter 26 attached to the carbonization chamber 21.

  Next, air or air and dry distillation gas were supplied from the blower 24 through the pipe 31 to the heating burner 23, and hydrocarbon gas was supplied from the hydrocarbon gas supply device 25 through the pipe 32, and thus obtained. By burning the mixed gas, the carbonization chamber 21 disposed in the heating furnace 22 is heated. In this case, since the inside of the carbonization chamber 21 is a reducing atmosphere and the amount of oxygen is extremely small, the waste ion exchange resin introduced into the carbonization chamber 21 is carbonized without burning.

  Therefore, since the generated or in-process carbides function as a reducing agent for chromium, the chromium reacts with oxygen in the atmosphere to form hexavalent chromium or is originally hexavalent. Even when chromium is contained, hexavalent chromium is reduced to trivalent chromium by the reducing action of the carbide. As a result, the amount of hexavalent chromium in the residue after treatment can be sufficiently reduced.

  In addition, it is preferable to perform the said heat processing, ie, a carbonization process, in the temperature range of 400 to 900 degreeC. When the temperature is lower than 400 ° C., the carbonization of the waste ion exchange resin is not sufficient, and when it exceeds 900 ° C., the waste ion exchange resin may be graphitized and may not exhibit the reducing action as described above.

  The temperature in the carbonization chamber 21 during the carbonization treatment can be appropriately measured and monitored by the thermocouple thermometer 27. Further, the oxygen concentration in the carbonization chamber 21 can be appropriately measured and monitored by the oxygen concentration meter 26. In this case, for example, depending on the type and amount of the waste ion exchange resin, if it is determined that the carbonization process proceeds too quickly, the oxygen concentration adjusting valve 28 provided in the pipe 33 is appropriately opened and closed. Thus, air or air and dry distillation gas can be supplied from the blower 24 into the carbonization chamber 21.

  Next, the residue after carbonization is introduced from the lower part of the carbonization chamber 21 into the solidified body producing apparatus 40 through the pipe 37 and is used for cement solidification. The introduction of the residue after the carbonization treatment into the solidified body manufacturing apparatus 40 can be performed, for example, using exhaust force from a pump (not shown) provided in the pipe 37.

  It is preferable that the cement used when forming the cement solidified body of the residue introduced into the solidified body manufacturing apparatus 40 is, for example, alumina cement, blast furnace slag cement, fly ash cement, and Portland cement. Since these cement materials are easily available, are inexpensive, and are stable against seawater and chemical substances, as cement materials that solidify and stabilize the residue after carbonization as in this embodiment. Is suitable. In particular, alumina cement is made of bauxite and limestone, which are raw materials of aluminum, and is a cement containing aluminum oxide, and exhibits high strength immediately after kneading, and therefore has excellent ion confinement properties.

  Additives such as an aggregate, a fluidizing agent, and a coagulation reaction accelerator can be blended with the above-described cement as necessary.

  The cement kneading water is generally ion-exchanged water when solidifying waste ion-exchange resin from nuclear facilities, but tap water or waste water may also be used. .

  As described above, according to the present embodiment, the waste ion exchange resin containing chromium is carbonized, and the produced carbide is used as a reducing agent for chromium to suppress the production of hexavalent chromium. Therefore, the amount of hexavalent chromium contained in the residue can be sufficiently reduced, and a residue containing no harmful hexavalent chromium can be obtained and used for cement solidification. Therefore, the waste ion exchange resin containing chromium can be used for cement solidification stably and safely, and the waste ion exchange resin can be disposed of safely and reliably.

  In the following examples, in order to confirm the effect of the present invention, an ion exchange resin containing chromium was carbonized, and the amount of hexavalent chromium in the residue obtained thereafter was examined. In addition, the carbonization process of each Example shown below was implemented using the carbonization apparatus 10 as shown in FIG.

Example 1
As an ion exchange resin, 500 ml (300 g) of Diaion EMK (manufactured by Mitsubishi Kasei Co., Ltd.) was used, and 5.0 g of chromium (ion) was adsorbed thereto. The water content of the ion exchange resin was 50% by mass.

  Next, the ion exchange resin is filled in a stainless steel container having a capacity of 100 cc equipped with an oxygen concentration meter and a thermocouple thermometer, and the stainless steel container is placed in a combustion furnace without flowing nitrogen gas. The container is evacuated so that the oxygen concentration in the container is 0.1 to 0.3% by volume, and heat-treated so that the temperature becomes 600 ° C. (temperature in the heating furnace 800 ° C. to 900 ° C.) Carbonization treatment was performed for 4 hours.

  The weight of the residue after carbonization was 30 g, and the amount of hexavalent chromium in this residue was 0.05 g. The amount of hexavalent chromium in the residue was quantified by diphenylcarbazide absorptiometry.

(Example 2)
The ion exchange resin was carbonized in the same manner as in Example 1 except that the temperature of the heat treatment was changed from 600 ° C to 900 ° C. The weight of the residue after carbonization was 30 g, and the amount of hexavalent chromium in this residue was 0.03 g. The amount of hexavalent chromium in the residue was quantified by diphenylcarbazide absorptiometry.

(Example 3)
The ion exchange resin was carbonized in the same manner as in Example 1 except that nitrogen gas was supplied into the stainless steel container at a flow rate of 0.5 to 1 L / min. The weight of the residue after carbonization was 30 g, and the amount of hexavalent chromium in this residue was 0.13 mg. The amount of hexavalent chromium in the residue was quantified by diphenylcarbazide absorptiometry.

Example 4
The ion exchange resin was carbonized in the same manner as in Example 2 except that nitrogen gas was supplied into the stainless steel container at a flow rate of 0.5 to 1 L / min. The weight of the residue after carbonization was 30 g, and the amount of hexavalent chromium in this residue was 0.72 mg. The amount of hexavalent chromium in the residue was quantified by diphenylcarbazide absorptiometry.

  As can be seen from the examples, when the ion exchange resin containing chromium is carbonized, the ratio of hexavalent chromium in the obtained residue is less than the order of ppc with respect to the total amount of chromium. I understand. In particular, it can be seen that the ratio of hexavalent chromium in the residue obtained by carbonization in a nitrogen gas atmosphere is on the order of several hundred ppm. Therefore, a residue containing almost no harmful hexavalent chromium can be obtained, and can be used for cement solidification stably and safely. As a result, the waste ion exchange resin can be disposed of safely and reliably.

  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 Processing apparatus of waste ion exchange resin containing chromium 20 Carbonization apparatus 21 Carbonization chamber 22 Heating furnace 23 Heating burner 24 Blower 25 Hydrocarbon gas supply apparatus 26 Oxygen concentration meter 27 Thermocouple thermometer 28 Oxygen concentration adjustment valve 31, 32, 33 , 37 Piping 40 Solidified body production equipment

Claims (10)

A method for treating waste ion exchange resin containing chromium,
Carbonizing the waste ion exchange resin;
Solidifying the residue after carbonization with cement;
A method of treating waste ion exchange resin containing chromium, comprising:   The said carbonization process is performed in a reducing atmosphere, The processing method of the waste ion exchange resin containing chromium of Claim 1 characterized by the above-mentioned.   The method for treating a waste ion exchange resin containing chromium according to claim 2, wherein the oxygen concentration in the reducing atmosphere is 1% by volume or less.   The said carbonization process is performed in the temperature range of 400 to 900 degreeC, The processing method of the waste ion exchange resin containing the chromium as described in any one of Claims 1-3 characterized by the above-mentioned.   The cement used for the cement solidification is at least one selected from the group consisting of Portland cement, blast furnace cement, fly ash cement, and alumina cement, according to any one of claims 1 to 4. A method for treating waste ion exchange resin containing chromium.   The waste ion exchange resin is a pellet-like or granular exchange resin obtained by granulating a predetermined resin composition as a binder, and contains chromium according to any one of claims 1 to 5. Treatment method of waste ion exchange resin. A processing apparatus for waste ion exchange resin containing chromium,
A carbonization device for carbonizing the waste ion exchange resin;
A solidified body preparation apparatus for cementing the residue after carbonization;
A processing apparatus for waste ion exchange resin containing chromium, comprising:   The said carbonization apparatus contains the carbonization chamber which puts the said waste ion exchange resin, and the heating apparatus for heating this carbonization chamber and performing the said carbonization process, The chromium of Claim 7 characterized by the above-mentioned. Waste ion exchange resin processing equipment.   The treatment apparatus for waste ion exchange resin containing chromium according to claim 7 or 8, wherein the carbonization apparatus is provided with an oxygen concentration meter and / or a thermometer.   The treatment apparatus for waste ion exchange resin according to claim 9, wherein the carbonization chamber includes an oxygen concentration adjusting valve whose opening degree is controlled by the oxygen thermometer and / or an output of the thermometer.

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