JP7126580B2 - Method for treating borate waste liquid - Google Patents

Description

The present invention relates to a method for treating borate waste liquid, in particular to a method for treating radioactive borate waste liquid.

Natural elemental boron contains about 80% boron-11 and about 20% boron-10. Among them, boron-10 is an excellent neutron absorber. Therefore, in a pressurized water reactor (PWR), boric acid is used as a neutron absorber for reactor cooling water in order to adjust the neutron density of the cooling water. Boric acid is also added to spent nuclear fuel pond water to adjust the neutron density of the pond water. These boric acid solutions are neutralized by the addition of an alkaline aqueous solution (e.g., sodium hydroxide) to become radioactive waste liquids containing sodium borate (hereinafter referred to as "boric acid (referred to as "salt effluent"). Radioactive borate liquid waste must be solidified to isolate it from human living areas and prevent its radioactivity from harming humans or the environment. Solid waste that meets quality and safety requirements ( Only after it becomes a solid waste form, it becomes possible to conduct final disposal. The term "final disposal" here is a term of art for radioactive waste management, the construction of multiple engineering barriers facilities in suitable geology to permanently isolate and bury radioactive waste. point to

Conventional solidification treatment methods for radioactive borate wastewater include cement solidification, polymer resin solidification, asphalt solidification, and the like. However, since organic solidifying agents such as polymeric resins and asphalt are not compatible with inorganic salt waste liquids, solid waste generated by solidification undergoes a salting-out phenomenon. In addition, polymer resin and asphalt are biodegradable. Therefore, it is not suitable for solidifying inorganic salt waste liquid.

The cement solidification method uses cement and Pozzolanic Materials as solidifying agents, and in addition to being able to solidify the waste liquid through the hydration reaction of cement, inorganic salts can be formed into hard solids. can. However, if the boron concentration is higher (e.g., boron concentration > 2 wt%) when solidifying the borate waste liquid using the cement solidification method, a significant solidification retardation phenomenon occurs, and the cement granules The hydration reaction of cement is inhibited by the formation of a hard calcium borate film on the surface of the cement. Therefore, traditionally, the cement solidification of the borate waste liquid is all done at a low boron concentration, or by adding slaked lime before solidification by the addition of cement, in order to reduce the phenomenon of retardation of solidification. process. Further, for example, in Patent Documents 1 to 7, etc., in order to reduce the solidification retardation phenomenon, basically an alkaline precipitant is used or added, and highly water-soluble sodium borate is used to form a low water-soluble borate precipitate. and then solidified by adding cement or asphalt. However, (1) the added alkaline precipitant greatly increases the amount of cement waste, and (2) when solidifying the waste liquid, it is still necessary to use a large amount of cement solidifying agent. The volume of waste increases significantly, the cost of managing radioactive waste is very high, and land for final disposal is difficult to find. Therefore, it is not economical to treat borate effluent with conventional cement solidification methods.

In order to reduce the volume of the cement solidified body and increase its boron content, JGC Corporation added lime to the borate waste liquid at a temperature of 40-60°C, stirred for about 10 hours, and added borate. (usually in the form of sodium salt) is converted into a more stable calcium borate precipitate, the precipitate is filtered and dehydrated, and then solidified with a cement solidifying agent, the so-called advanced cement solidification method. Solidification Process) was developed. However, this method is time consuming to operate and produces a secondary waste containing sodium hydroxide that needs to be disposed of.

In addition, in Patent Document 8, it is possible to increase the boron load of the waste without generating secondary waste by solidifying the borate waste liquid into a polymerized borate waste liquid with a high degree of polymerization and then solidifying it with cement. method is disclosed. However, the solidified body produced by this method has relatively low immersion resistance, which limits its application when immersion resistance is strictly required.

U.S. Pat. No. 4,293,437 U.S. Pat. No. 4,210,619 U.S. Pat. No. 4,800,042 U.S. Pat. No. 4,906,408 U.S. Pat. No. 4,620,947 Chinese Patent Application Publication No. 102800377 China Patent No. 102254579 U.S. Pat. No. 5,457,262

For the treatment of borate effluent, a method that does not produce secondary waste, produces highly water-resistant, boron-loaded waste, greatly reduces volume, and significantly reduces management costs. is desired.

The method for treating borate effluent provided by the present invention includes the steps of preparing the original borate effluent feed to a low concentration effluent suitable for concentration, and concentrating the low concentration effluent to a high concentration effluent. a step of granulating by a solidification action with a high-concentration waste liquid and a granulating agent; a step of preparing a hardenable slurry; and a step of producing waste, including the production of granule compaction block fixed waste (hereinafter abbreviated as fixed body).

The original effluent feed is a low borate containing effluent that, after preparation with the modifier, becomes a low effluent suitable for concentration. A high-concentration borate waste liquid containing polymerized borate with a high degree of polymerization (hereinafter abbreviated as high-concentration waste liquid) is prepared by concentration from the low-concentration waste liquid, and then a granulating agent (ie, a solidifying agent) is prepared. Granulation is performed by the solidification reaction with decrease significantly. In addition, since the granulation is carried out using high-concentration borate waste liquid, borate granules with a hard texture are formed, and then after solidification treatment with a hardenable slurry, disposal with high mechanical strength and high water resistance things are formed. Here, the process of mixing borate granules and a hardenable slurry to produce a high mechanical strength, high water resistance monolithic waste form is described as a process for finely divided waste ion exchange resins, sludge, residues and the like. Based on the colloquial terminology for granular solid waste solidification, it is referred to as solidification. This idiomatic term will be used as it is in the following description.

1 is a schematic flow diagram of a method for treating borate wastewater according to one embodiment of the present invention; FIG. 1 is a schematic flow diagram of fabricating a solidified body package in one embodiment of the method of the present invention; FIG. 1 is a schematic flow diagram of fabricating a stator package in one embodiment of the method of the present invention; FIG.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the following detailed description is given by way of example, together with the accompanying drawings.

As shown in FIG. 1, the method for treating borate wastewater provided by the present invention is to convert the original borate wastewater 001 into low-concentration borate wastewater (hereinafter referred to as low-concentration low-concentration), which has a continuous composition and satisfies the conditions for concentration treatment. (abbreviated as waste liquid 003), and a high-concentration borate waste liquid containing polymerized borate with a high degree of polymerization (hereinafter abbreviated as high-concentration waste liquid 004). a step S200 for concentrating the low-concentration waste liquid, a step S300 for granulating the borate granules 006 from the high-concentration waste liquid, and a step S410 for producing a solidified package (as shown in ) for use in consolidating borate granules. Alternatively, a hardenable slurry is prepared according to step S420 (as in FIG. 3) to make the immobiliser package, the borate granules are compressed into compacted blocks and placed in a waste barrel, and then the hardenable slurry is poured. a waste package making step S400. "Package" herein refers to a collection of waste and waste-containing barrels. Each is described in detail below.

In preparing the effluent feed of step S100, the original borate effluent 001 can be, for example, different concentrations of sodium borate effluent from a nuclear power plant. The present invention is capable of treating sodium borate effluents with a variety of different boron concentrations. Any sodium borate effluent from a nuclear power plant usually undergoes a rudimentary pre-evaporation treatment. The original borate waste liquid entering the treatment process according to the present invention preferably has a boron concentration of 20000 ppm or more, more preferably 40000 ppm or more, and reduces the burden of evaporation and concentration of the treatment system according to the present invention. It is possible to

Step S100 further includes adjusting the molar ratio of sodium to boron in the original sodium borate effluent, eg, from a nuclear power plant. Furthermore, it is possible to adjust by adding the adjustment liquid to the original sodium borate waste liquid and mixing uniformly. The conditioning liquid can be, for example, a hydroxide solution of sodium, potassium, lithium, or the like. When using sodium hydroxide to prepare the sodium borate waste solution, it is preferred to have a sodium/boron molar ratio of 0.25 to 0.35. Step S100 further includes adjusting the pH value of the original sodium borate waste solution. The modifier can be selected from boric acid, sulfuric acid, phosphoric acid or sodium hydroxide, calcium hydroxide, barium hydroxide and the like.

In the concentration of the low-concentration waste liquid in step S200, the concentration of the waste liquid is usually carried out by a heating method, and the device used is at least one of a stirred tank evaporator, a forced circulation evaporator, or a thin film evaporator. It is also possible to use both at the same time depending on the The sodium borate effluent feed becomes low concentration effluent 003 after being prepared by step S100. In this step S200, the low-concentration waste liquid 003 is concentrated into a high-concentration waste liquid 004 containing sodium borate with a high degree of polymerization. The high-concentration waste liquid 004 preferably has a boron concentration of at least 100,000 ppm, more preferably 110,000 ppm or more, and most preferably 120,000 ppm or more. However, the high-concentration waste liquid 004 is viscous, and it is necessary to prevent clogging or crystal formation. Higher boron concentration helps to form better quality granules with higher mechanical strength during volume reduction and subsequent granulation. However, considering that its viscosity may cause transportation difficulties, crystals and clogging, the boron concentration preferably does not exceed 130000 ppm.

The molar ratio of sodium to boron in the high-concentration waste liquid 004 prepared in step S200 is preferably maintained at 0.25 to 0.35, more preferably 0.28 to 0.32. The high-concentration waste liquid 004 must be kept at an appropriate temperature during storage, preferably 40 to 80°C. A relatively high temperature is beneficial in preventing the formation of crystals, but too high a temperature is detrimental to the properties of the granules produced by granulation. Therefore, it is possible to keep the temperature relatively high during storage, and again to lower the temperature slightly when granulation approaches.

In the granulation of the high-concentration waste liquid in step S300, for example, cementitious materials, pozzolanic materials, oxides or hydroxide powders of divalent or more than divalent alkaline earth metals, transition metals Granulating agent 005 can be prepared using materials selected from oxide or hydroxide powders, metalloid oxide or hydroxide powders, and combinations thereof. The granulating agent 005 can also include transition metal or semi-metal silicate, phosphate, carbonate or complex powders, or combinations thereof. In addition to the self-prepared granulating agent according to the above ingredients, a suitable commercially available sludge solidifying agent or the like may be selected directly. High concentration sodium borate waste liquid and granulating agent form borate granules by solidification reaction. During the reaction, the liquid high degree of polymerization sodium borate undergoes a substitution reaction with the granulating agent to form solid high degree of polymerization polymeric borate granules. The borate composition and mechanical strength of granules are primarily determined by the ingredients of the granulating agent.

As the granulator, known equipment can be used, and it is also possible to design it separately. The high-concentration waste liquid 004 of the embodiment of the present invention has viscosity, and the semi-finished granules in the process have high viscosity. Preferably to prevent or reduce. For example, a drum granulator or a stirred tank granulator is used. The internal structure of the drum granulator is simple, which helps reduce sticking of materials or semi-finished products. The agitating tank type granulator preferably has a planetary rotation and a rotation agitating blade, which is useful for forming granules with high density and good mechanical strength.

The granulation step of step S300 can include an initial granulation step S310 and a continuous granulation step S320. Step S310 is granulation when there are no granules yet, and it is necessary to preset the granulating agent 005 in the granulator. The amount should be sufficient to cover the stirring blades. After the preset granulating agent has been brought in, the stirring blades are started to roll and flow the granulating agent 005, and then a predetermined amount of high-concentration waste liquid 004 is slowly added in several portions. . The high-concentration waste liquid 004 contacts the tumbling/flowing powder of the granulating agent 005 and then undergoes a solidification reaction to form borate granules 006 . After a predetermined amount of high-concentration waste liquid has been brought in, stirring is continued for 3 to 5 minutes to complete the initial granulation. Typically, step S310 only needs to be performed once. Step S320 is granulation when there are already granules in the granulator, it is possible to place the borate granules 006 obtained in the initial granulation or pre-made into the granulator, Next, after starting the stirring blade, add the granulating agent and the high-concentration waste liquid in a cross manner, and the order of addition of both can be freely selected to ensure the uniformity of the granule properties. It is preferable that the ratio of the amount of both added is fixed. Step S320 can be performed repeatedly until a sufficient amount of granules has been produced. If the granules produced reach the capacity limit of the granulator, granulation can be suspended, removed some finished granules, and then resumed.

The total weight of the granulating agent 005 used in step S300 is preferably less than the total weight of the high-concentration waste liquid 004. The ratio between the amount of the granulating agent 005 used and the amount of the high-concentration waste liquid 004 used in step S310, step S320, or all S300 depends on the hardening reaction equivalent of the granulating agent 005, granulation operability, demand for granule properties, etc. can be determined based on Also, in step S310, it is generally preferable to use a higher proportion of the granulating agent 005 to prevent the occurrence of sticking phenomena. In step S320, the weight ratio of the granulating agent 005 and the high-concentration waste liquid 004 is about 0.2-0.6. The speed of agitation in steps S310, S320 can be determined based on the granulator used (eg, the type of granulator), the nature of the material and semi-finished product, and the desired granule size. For example, rapid agitation can be used to form relatively small granules. Preferably, the borate granules 006 of the examples of the present invention have a diameter of 2-5 mm. The granulator can further comprise controlling the size of the discharged granules, for example using a screen.

Making a waste package in step S400 can include step S410, making a solidified body package, and step S420, making a solid body package. As shown in FIGS. 1-2, step S410 includes making a settable slurry, making a granular solidified slurry body, and barreling. The hardenable slurry 009a, which can be selected from one of, for example, cement slurry, concrete slurry, gypsum slurry, etc., is made of hardenable slurry raw material 007a and additive solution 008a prepared with water and additives. do. Preparation of the solidified granule slurry body 010 includes mixing borate granules 006 (the borate granules used in step S410 are also designated 006a) and hardenable slurry 009a to harden the borate granules 006a. Sufficiently embedded in the granulated slurry 009a to result in a hardenable granulated solidified slurry body 010 . The solidified granular slurry body 010 is poured into a container, such as a waste barrel 012a (radioactive waste storage barrel), to form a solidified granular body, i.e. a large monolithic solid waste form, after the slurry body has hardened. do. Step S410 can further include curing the solidified body to obtain mature and stable quality (discussed below). The granule compact becomes a compact package 013 after capping together with the waste barrel 012a.

As shown in FIG. 3, step S420 includes barreling the granules, making a granule compaction block, barreling the granule compaction block, making a hardenable slurry, and placing the granule compaction block into a barrel followed by curing. and pouring and fixing the slurry. Kegging of the granules can normally be done using container 012c. After the granules have been barreled, the container 012c can generally be compressed with the borate granules 006b to form a granule compaction block 011. The kegging of the granule compression block 011 uses the waste keg 012b. Preparation of the hardenable slurry 009b is the same as the step of preparing the hardenable slurry 009a in S410 and will not be described. Securing the granule compaction blocks 011 includes pouring a hardenable slurry 009b into a waste barrel 012b containing several granule compaction blocks 011, filling the interstices with the hardenable slurry 009b and surrounding the granule compaction blocks 011. to form compacted block fixtures, ie large monolithic solid waste forms. Step S420 can also include curing the fixture. The compressed block fixture becomes a fixture package 014 after capping with the waste barrel 012b.

The method for treating borate waste liquid according to the present invention is further illustrated through Examples 1 to 6 below.

Steps S100-S200: 980 grams of deionized water was taken and placed in one 6 liter glass beaker equipped with an electric stirring blade and stirred by starting the electric motor. Subsequently, take 833 grams of 99% sodium hydroxide and 4340 grams of 99% boric acid, first with sodium hydroxide, then with boric acid in four portions, adding sodium hydroxide and boric acid to a beaker of water. was slowly added to the After the boric acid was completely dissolved, the solution volume was adjusted to 4200 milliliters with deionized water, and the solution temperature was adjusted to 80°C. After analysis, the resulting solution had a boron concentration of 121000 ppm (or 12.1 wt%), corresponding to a boric acid concentration of 69.21 wt%. The sodium/boron molar ratio was 0.297. The obtained solution was used as a simulated high-concentration waste liquid.

Step S300 (S310-S320): Take 90 parts of commercial sludge solidifying agent STA-110 (a product of EigenGreen International Inc.) and mix with 10 parts of reagent grade calcium hydroxide powder, followed by It was ground with a grinder and passed through a 150 mesh screen. The obtained powder was a granulating agent powder (granulating agent-A). The amount of granulating agent powder required can be proportionately adjusted according to demand based on the amount of concentrated waste liquid.

Initial granulation step S310: Performed using a stirring tank type granulator having planetary stirring blades. 1640 grams of granulator-A powder was taken and placed in the 20 liter granulator and the stirrer was started. Subsequently, 2350 g of the high-concentration waste liquid prepared in step S200 was taken and slowly added dropwise in several portions to the granulating agent powder being stirred. In order to reduce the sticking of the granules to each other, after each addition, waited for the high concentration effluent to disperse and form granules with the granulating agent, and the wet luster of the granules disappeared before adding the high concentration effluent again. . After adding the high-concentration waste liquid, stirring was continued for about 5 more minutes to complete the preparation of the initial borate granules. The weight ratio of granulating agent/high-concentration effluent used was 0.7 (see Table 1). As a supply method for starting granulation in S310, the necessary granulating agent was first added only once, and then the high-concentration waste liquid was added in multiple batches.

Continuous granulation step S320: leave the borate granules obtained in the initial granulation in the granulator and continue to stir, then take 200 grams of high-concentration waste liquid and drop it slowly into the granulator, It was evenly distributed on the granule surface. Then 80 grams of granulating agent was taken and added onto the stirred granules. After waiting for the concentrated effluent to react with the granulating agent and convert it into solid granules and lose its wet luster, the concentrated effluent was added again. In this way, the high-concentration waste liquid and the granulating agent are circulated and repeatedly added 14 times, and a total of 2800 grams of the high-concentration waste liquid and 1120 grams of the granulating agent are added, and then stopped to complete the granulation of borate granules. let me In the continuous granulation of S320 above, the granulating agent and the high-concentration waste liquid are divided into multiple times and added in a circulation repeat method based on a predetermined ratio, and the weight ratio of the granulating agent/high-concentration waste liquid used is 0. .4. After finishing, stirring was continued for 5 minutes, then all the granules were taken out and allowed to proceed with the subsequent process.

As shown in Table 1, Example 1 used a total of 2760 grams of granulating agent and 5150 grams of concentrated waste liquid. The diameter of borate granules was mainly distributed between 2 and 5 mm. After calculation, the boron content of the granules was 7.88 wt%, corresponding to a boric acid content of 5.06 wt%.

Step S400: Commercially available solidifying agent ECOCRETE-FS (a product of EigenGreen International Inc.), quartz powder (granule size ranges from 70 to 150 mesh) can be hardened slurry raw material used as Take 1460 grams of solidifying agent (ECOCRETE-FS) and 1350 grams of quartz powder, put into a 20 liter planetary stirrer, start stirring, add 840 grams of water, mix evenly to obtain 3650 grams of hardening A possible slurry was made. Subsequently, take 3500 grams of the borate granules made in step S300, add them to the stirred hardenable slurry, mix evenly into a granule solidified slurry body, and then make a granule with an inner diameter of 5 cm and a height of 6 cm. The slurry was placed in a cylindrical polyethylene plastic mold. After air bubbles were removed by a vibrating method to flatten the surface, it was placed in a constant temperature and humidity chamber at a temperature of 25° C. and a relative humidity of 95% for curing for 28 days. After calculation, the weight of the hardenable slurry of Example 1 is 1.04 times that of the borate granules, and the boron content of the resulting waste is 3.86 wt%, with 22.07 wt% boron. corresponded to the acid content. After measurement, the specific gravity of the solidified slurry body was 1.87, so its boron loading factor was 72.16 kg/m ³ , corresponding to a boric acid loading factor of 412.69 kg/m ³ .

After curing for 28 days, the solidified slurry was released from the mold, cut into 5-centimeter-diameter cylindrical solidified bodies with a height of 5 centimeters, and tested for compressive strength and weather resistance (freezing Melting resistance), immersion resistance, etc. were tested. A 9-meter drop impact resistance test was also conducted. The results were as shown in Table 2.

Steps S100-S200: A simulated high-concentration waste liquid was prepared according to the steps and methods of Example 1, and its boron concentration and sodium/boron molar ratio were as shown in Table 3.

Step S300: Take a commercially available sludge solidifying agent STA-110 (a product of EigenGreen International Inc.) and reagent grade calcium hydroxide powder, mix by weight 1:1, and then use the A granulating agent powder (granulating agent-B) was prepared according to the steps.

Step S300 (S310-S320): Granulation is performed according to the steps and methods of Example 1 and based on the material conditions in Table 3, and the borate granules obtained have a boron content of 8.28 wt% and 47 This corresponded to a boric acid content of 0.36 wt %.

Step S400: The same hardenable slurry as in Example 1 was used. A granule-solidified slurry body was made using a settable slurry/borate granule weight ratio of 0.65 according to the process of Example 1. The boron content of the resulting solidified slurry body was 5.01 wt%, corresponding to a boric acid content of 28.64 wt%. After measurement, the specific gravity of the solidified slurry body was 1.87, so its boron loading factor was 93.65 kg/m ³ , corresponding to a boric acid loading factor of 535.62 kg/m ³ .

According to the steps of Example 1, solidified samples were prepared and properties were tested. The results were as shown in Table 4.

Steps S100 to S200: A high-concentration waste liquid was prepared according to the steps and methods of Example 1, and the boron concentration and sodium/boron molar ratio of the high-concentration waste liquid were as shown in Table 5.

Step S300 (S310 to S320): Granulation was carried out according to the steps of Example 1 and using granulating agent-B based on the material conditions in Table 5. The boron content of the resulting sodium borate granules was 8.61 wt%, corresponding to a boric acid content of 49.26 wt%.

Step S400: The same hardenable slurry as in Example 1 was used. A granule-solidified slurry body was made using the settable slurry/sodium borate granule weight ratio of 0.82 according to the process of Example 1. Next, curing was performed according to the steps of Example 1. The boron content of the resulting waste was 4.73 wt%, corresponding to a boric acid content of 27.07 wt%. After measurement, the specific gravity of the solidified slurry body was 1.86, so its boron loading factor was 88.03 kg/m ³ , corresponding to a boric acid loading factor of 503.5 kg/m ³ .

According to the steps of Example 1, solidified samples were prepared and properties were tested. The results were as shown in Table 6.

Steps S100 to S200: A high-concentration waste liquid was prepared according to the steps and methods of Example 1, and the boron concentration and sodium/boron molar ratio of the high-concentration waste liquid were as shown in Table 7.

Step S300: Granulator powder according to the process of Example 1 with 40 parts of commercial sludge solidifying agent STA-110 (a product of EigenGreen International Inc.) and 30 parts of barium hydroxide monohydrate. (Granulating agent-C) was prepared.

Step S300 (S310-S320): Steps S310-S320 were performed according to the steps and methods of Example 1 using the material conditions in Table 7. In step S320, each time, 200 grams of high-concentration waste liquid is added first, and then 83 grams of granulating agent is added. The granules produced were close to the capacity limit of the granulator, so the operation was temporarily suspended, half the weight of sodium borate granules was taken out, and granulation was continued in the same manner, and the high-concentration waste liquid and granulation were continued. After 50 cyclic repeat additions of each agent, it was stopped and the granulation of sodium borate granules was completed. In step S320, a total of 20,000 grams of high-concentration waste liquid and 8,300 grams of granulating agent were added, adding a total of 100 times each of the high-concentration waste liquid and the granulating agent. Subsequently, all sodium borate granules were collected and mixed, awaiting further processing.

As shown in Table 7, the weight ratio of granulating agent/high-concentration effluent used in Example 4 was 0.454 on average, and the diameter of sodium borate granules was mainly between 2-5 mm. distributed. After calculation, the boron content of the granules was 8.26 wt%, corresponding to a boric acid content of 47.25 wt%.

Step S400: Using 40 parts of commercial nuclear waste treatment solidifying agent ECOCRETE-RS (a product of EigenGreen International Inc.), 35 parts of quartz powder and 25 parts of water, A hardenable slurry was made according to the process. Subsequently, a granule solidified slurry body was prepared according to the steps of Example 1 using a 1.12 weight ratio of the settable slurry/sodium borate granules. The boron content of the resulting solidified slurry body was 3.89 wt%, corresponding to a boric acid content of 22.25 wt%. After measurement, the specific gravity of the solidified slurry body was 1.87, so its boron loading rate was 72.74 kg/m ³ , corresponding to a boric acid loading rate of 416.04 kg/m ³ .

Solidified body samples were prepared according to the steps of Example 1 and tested for properties after curing for 28 days. The results were as shown in Table 8.

Steps S100 to S200: A high-concentration waste liquid was prepared according to the steps and methods of Example 1, and the boron concentration and sodium/boron molar ratio of the high-concentration waste liquid were as shown in Table 9.

Step S300: With 52 parts of commercial sludge solidifying agent STA-110 (a product of EigenGreen International Inc.), 36 parts of type II portland cement and 12 parts of reagent grade magnesium hydroxide, the A granulating agent powder (granulating agent-D) was prepared according to step 1.

Step S300 (S310-S320): carried out according to the steps of Example 4 based on the material conditions in Table 9, in which the weight ratio of granulating agent/high-concentration sodium borate waste liquid was 0.363 on average. rice field. The boron content of the resulting sodium borate granules was 8.81 wt%, corresponding to a boric acid content of 50.39 wt%. The diameter of the granules was mainly distributed between 2 and 5 mm.

Step S400: The same hardenable slurry as in Example 4 was used. A granule solidified slurry body was made using a 1 weight ratio settable slurry/sodium borate granule according to the process of Example 4. The boron content of the resulting solidified slurry body was 4.41 wt%, corresponding to a boric acid content of 25.2 wt%. After measurement, the specific gravity of the solidified slurry body was 1.88, so its boron loading factor was 82.79 kg/m ^{3 , corresponding to a boric acid loading factor of 473.5 kg/m 3 .}

According to the steps of Example 1, a solid sample was prepared, cured and tested for properties. The results were as shown in Table 10.

Steps S100-S200: A high-concentration waste liquid was prepared according to the steps and methods of Example 1, and the boron concentration and sodium/boron molar ratio of the high-concentration waste liquid were as shown in Table 11. In this example, 200 ppm of cobalt nitrate hexahydrate and 100 ppm of cesium nitrate were added to the high-concentration waste liquid to make it an experimental group in order to measure the leaching resistance of the solidified material. No cesium was added to the control group.

Step S300 (S310-S320): Granulating agent-A was used. Step S300 was performed according to the steps of Example 1 and based on the material conditions in Table 11. An experimental group and a control group were performed respectively. The boron content of the resulting sodium borate granules was 3.57 wt%, corresponding to a boric acid content of 20.39 wt%.

Step S400: Prepare a hardenable slurry according to the steps of Example 1 using 70 parts of commercial nuclear waste treatment specific solidifying agent ECOCRETE-RS (a product of EigenGreen International Inc.) and 30 parts of water. made. Subsequently, a granule solidified slurry body was prepared according to the steps of Example 1 using a 1.10 weight ratio of the settable slurry/sodium borate granules. An experimental group and a control group were performed respectively. The boron content of the resulting solidified body slurry was 3.57 wt%, corresponding to a boric acid content of 20.39 wt%. After measurement, the specific gravity of the solidified slurry body was 1.86, so its boron loading factor was 66.32 kg/m ³ , corresponding to a boric acid loading factor of 379.31 kg/m ³ .

For the experimental group and the control group, solidified sample preparation, curing and property testing were performed according to the steps of Example 1, respectively. ) was used to perform the leaching resistance test. The property test results of the experimental groups are shown in Table 12, and all met the property standard requirements. The presence of cobalt and cesium was not detected in the control leachate.

Although Examples 1-6 all formed sodium borate granules into compacted granules according to step S410, it is also possible to form sodium borate granules into compressed block compacts according to step S420, as previously described. However, the property definition of the fixed body, unlike the solidified body, usually requires that it be provided with a stable outer sealing layer of constant thickness. Embodiments of the present invention demonstrate that the various hardenable slurries produced can form hardened bodies with good properties, and are well poured to surround and secure compacted blocks to produce solid bodies with good properties. Proved enough to get.

In short, the treatment method of the present invention is capable of producing a high boron loading factor waste with superior properties and achieving waste volume reduction. The granulation method of the present invention is simpler and easier to implement than known methods, does not generate secondary liquid waste, and can significantly reduce the cost of managing radioactive waste.

Although the present invention has been disclosed above with examples, it is not intended to limit the invention. Those skilled in the art to which this invention pertains can make several changes and modifications without departing from the spirit and scope of this invention. Therefore, the scope of protection of the present invention is defined by the appended claims.

Process code:
S100: Preparation of effluent feed S200: Concentration of low concentration effluent S300: Granulation of high concentration effluent S400: Preparation of waste package S410: Preparation of solid package S420: Preparation of solid package Material code:
001: original borate effluent 003: low concentration effluent 004: high concentration effluent 005: granulating agents 006, 006a, 006b: borate granules 007a, 007b: hardenable slurry raw materials 008a, 008b: water + additive 009a , 009b: hardenable slurry 010: granule solidified slurry body 011: granule compression block 012a, 012b: waste barrel 012c: ordinary container 013: solidified body package 014: fixed body package

Claims (12)

preparing a effluent feed to obtain a low borate effluent;
a step of concentrating the low-concentration borate waste liquid to obtain a high-concentration waste liquid containing polymerized borate with a high degree of polymerization and having a boron concentration of at least 100000 ppm ;
granulating the high-concentration waste liquid with a granulating agent to form a plurality of solid borate granules;
creating a large monolithic solid waste from the plurality of solid borate granules;
including
forming the plurality of solid borate granules comprises an initial granulation step and a continuous granulation step;
In the initial granulation step,
An appropriate amount of the granulating agent is placed in a granulating device having a stirring blade, the powder of the granulating agent sufficiently covers the stirring blade, and the stirring blade is started to stir the granulating agent. ,
The high-concentration waste liquid containing the polymerized borate having a high degree of polymerization is added in the form of droplets to the granulator, brought into contact with the powder of the granulating agent being stirred, and solidified to form granules. death,
when the weight ratio between the placed granulating agent and the high-concentration waste liquid added (granulating agent/high-concentration waste liquid) reaches a first weight ratio, stopping the addition of the high-concentration waste liquid ;
In the continuous granulation step,
starting stirring to stir the granules obtained in the initial granulation step;
According to a second weight ratio, the granulating agent and the high-concentration waste liquid are added to the granulation device in a cloth manner, the weight of the high-concentration waste liquid and the humidity of the granules are controlled each time, and the second weight ratio is the ratio is less than the first weight ratio;
removing a plurality of solid borate particles when the plurality of solid borate granules produced reaches the capacity limit of the granulator;
A method of treating a borate effluent to produce a concentrated effluent containing polymerized borates with a high degree of polymerization, a plurality of solid borate granules, and a large monolithic solid waste. creating the large monolithic solid waste from the plurality of solid borate granules comprising:
preparing a hardenable slurry;
mixing the solid borate granules and the settable slurry into a settable granular slurry;
2. The method of claim 1, comprising placing the body of granular slurry in a waste keg and forming a compacted granular body package after the body of granular slurry has hardened. creating the large monolithic solid waste from the plurality of solid borate granules comprising:
preparing a hardenable slurry;
after the solid borate granules have been placed in a barrel, they are compacted into at least one compacted block, and the at least one compacted block is placed in a waste keg;
pouring said hardenable slurry to surround said at least one compacted block to fill voids within said waste barrel to form a granular compacted block stator package after said hardenable slurry hardens. Item 1. The method according to item 1. 2. The method of claim 1, wherein the effluent feed is sodium borate effluent. 5. The method of claim 4, wherein the sodium borate effluent is adjusted to a sodium to boron molar ratio of 0.25 to 0.35 in the effluent feed. 2. The step of preparing the waste feed further comprising adjusting the pH value of the waste feed using a compound selected from boric acid, sulfuric acid, phosphoric acid and sodium hydroxide. described method. The high-concentration borate waste liquid containing the polymerized borate with a high degree of polymerization is a high-concentration waste liquid containing sodium borate with a high degree of polymerization, and has a boron concentration of at least 100000 ppm. Method. The high-concentration borate waste liquid containing a polymerized borate with a high degree of polymerization is a high-concentration waste liquid containing sodium borate with a high degree of polymerization .
The method of claim 1. The granulating agent powder is a cement-based material, a pozzolanic material, a divalent or more than divalent alkaline earth metal oxide or hydroxide, a transition metal oxide or hydroxide, a metalloid oxide or water. 9. The method of claim 8, prepared from a material selected from oxide, silicate, phosphate, carbonate or complex powders, or combinations thereof. 9. The method according to claim 8, wherein the granulator is a planetary stirred tank with revolution and rotation functions. 9. The method according to claim 8, wherein the total weight of the high-concentration waste liquid containing the polymerized sodium borate with a high degree of polymerization used during granulation exceeds the total weight of the granulating agent powder. In the continuous granulation step,
When removing the plurality of solid borate granules, a suitable amount of granules is left in the granulator to serve as initial granulation for another granulation.
The method of claim 1 .

Images