KR20170030388A - High efficiency electrokinetic treatment method for uranium contaminated soil using the ion-exchange resins - Google Patents

Abstract

The present invention relates to a method for collecting and removing uranium which is a radioactive contaminant material contained in soil. According to the present invention, an electrokinetic treatment method for soil, unlike a conventional method for treating all of the samples by using galvanic electricity, is to separate fine soil to treat only the fine soil through galvanic electricity and to simply decontaminate coarse particles through washing. In addition, uranium in a cleaning solution is selectively removed by using ion exchange resin and reduces secondary radioactive waste of at least 90% by recycling the used ion exchange resin.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrochemical high-efficiency uranium contaminated soil treatment method using an ion exchange resin,

The present invention relates to a decontamination method in which a soil contaminated with uranium is treated in an initial pickling process by separating and micro-finishing the micro-soil to enhance the treatment efficiency, and a method of removing uranium selectively from the waste solution generated in the treatment process using an ion exchange resin The present invention relates to a method of treating a contaminated soil containing uranium, which can reduce the radioactive waste by recycling and reusing the used ion exchange resin.

Demand for nuclear power generation systems has surged along with the surge in the use of power for domestic industrial and household use. Uranium exploitation projects have been carried out in Korea to stabilize the supply and demand of uranium raw materials. However, the uranium contaminated soil that has not been treated after the initial mining process is reflected in the surrounding environment and the opinions of the nearby residents, is being stored for a long period of time, and social costs are incurred due to the expense for disposal and the acceptance limit of the radioactive shield.

Recently, electrokinetic contaminated soil restoration technology has been developed to solve this problem. Electrokinetic contaminated soil treatment is a technique to decontaminate charged contaminants by supplying electricity to wet soil. More specifically, the electrolytic decontamination process is described in detail. The hydrogen ion generated from the anode moves between the two electrode plates to which the potential difference causing the electrolysis reaction of water is applied. The solubility and the solubility of various contaminants in the soil such as uranium This means an effective decontamination method that increases mobility. The Applicant has secured a technical element for the uranium treatment through a patent on the compound electrokinetic soil decontamination apparatus which disclosed the electrodialysis technology (Korean Patent No. 1292962, July 29, 2013).

In recent years, as a process of uranium contaminated soil treatment technology, there has been proposed a column treatment method in which a leaching solution in which uranium is leached is put into a reaction tank, or an ion exchange resin is fed into a uranium-enriched slurry leached from a raw material, A resin-in-pulp method in which a resin is directly adsorbed on a substrate is mainly used.

However, in this resin-in-pulp system, a very large amount of sample can be obtained by such a single process because of the very slow processing time of several hundreds of hours in the process of mixing and stirring the slurry containing the uranium leaching solution and the ion- Is not industrially suitable.

In addition, the uranium adsorbed resin additionally generated in this process has a problem of producing a large amount of another radioactive waste, and a method for effectively treating uranium contaminated soil is required.

Korean Patent Registration KR10-0526993 Korean Patent Registration KR10-1039595

&Quot; Treatment Methods for Radioactive Wastes and Their Electrochemical Applications ", V. Valdovinos, F. Monroy-Guzman and E. Bustos, Environmental Risk Assessment of Soil Contamination, InTech, Chapter 14, 397-426,

The existing decontamination process of uranium contaminated soil uses a method of decontaminating all the soil after the pickling in the electrolysis. The electrokinetic treatment (S150) process of FIG. 1 is a process for removing radioactive waste to remove uranium from contaminated soil to a level lower than a 'disaster-resistant standard' capable of being buried in a general ecosystem. In more detail, in the process of FIG. 1, the disposal of the soil itself is performed in accordance with Article 2 (1) of the Radioactive Waste and its Disposal Standards (Nuclear Safety Commission Notice No. 2014-003, 2014.9.16) Which is determined to be less than the allowable concentration of its own disposal, is excluded from the scope of [Nuclear Safety Act] and is managed by incineration, landfill or recycling as general waste rather than radioactive waste. In addition, the permissible concentration of uranium isotopes is 0.1 Bq / g for U-232, which is the lowest among uranium isotopes, while for U-231, U-237, U-239 and U-240 Is the highest value of 100 Bq / g. However, as in the case of the present invention, the standards for permissible disposal of natural uranium, U-235 and U-238, are not defined. However, referring to the provisions of the International Atomic Energy Agency (IAEA), in the present invention, when the total radioactivity of uranium including U-234, which is a daughter nucleus of U-235, U-238 and U-238 is 1 Bq / g or less, The permissible level of disposal was determined.

Conventional cleaning / electroplating processes require a long term decontamination period of one month or more by electrokinetic treatment of all the soils after washing, high power consumption, heat generation during electrode reaction, and nitric acid A small amount of NOx gas is generated. In addition, sodium hydroxide (NaOH), potassium hydroxide (KOH) or calcium oxide (CaO) is added to the acid wastewater from which the soil is washed to raise the pH to around 9 to lower the solubility of uranium and treat the precipitated uranium as a secondary radioactive waste The conventional method has a problem that a considerable amount of secondary radioactive waste is generated because not only uranium but also metals such as iron and aluminum dissolved in an acid solution are precipitated at around pH 9.

The present invention relates to a method for improving the decontamination process of radioactive contaminated soil using a conventional copper electroplating. Unlike the conventional method, in the 'primary pickling' process of radioactive contaminated soil, only fine soil is separated and decontaminated by the electric furnace, and the remaining thick soil is simply decontaminated by the pickling process, so that the amount of the sample Can be reduced to about 1/3, so that not only the number of the electric devices but also the processing time can be greatly reduced. In addition, the method proposed by the present invention aims at providing a new treatment method capable of reducing the amount of the secondary radioactive waste generated in the treatment of the soil washing waste solution by 90% or more.

 However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

In the decontamination method of radioactive contaminated soil by using electricity, the present invention can treat the uranium contaminated soil as shown in Fig. 1 by the following process.

In the present invention, the uranium contaminated soil is put into the hopper, the fine soil is separated through the 'first pickling step' (S110) (S120), the remaining particles are again introduced into the 'second pickling step' (S130) (S140) of separating the fine soil again, and the coarse particles are decontaminated without the electroplating process (S150). At this time, the step (S120) of separating the fine soil firstly and the step (S140) of the second separation are steps of filtering the acid suspension.

In the present invention, a soil suspension generated in decontamination of a uranium-contaminated soil is filtered through a 100 mesh sieve having a pore size of about 0.15 mm, and the solution is filtered with a filter press having a filter having a pore size of 0.02 mm Squeeze and separate soil and water. That is, the particles between about 0.15-0.02 mm were separated into fine particles and treated with the electrokinetic method (S150). The sieving method uses a wet vibration method in which a suspension is poured into a vibrating body to prevent clogging. Sieve particles are treated as particles larger than fine soil.

The present invention is constructed so as to reduce the amount of the sample to be decontaminated and to shorten the decontamination period, as a method of introducing only the separated micro-soot after the micro-soot separation process into the electro-chemical treatment process (S150).

Also, in the present invention, the washing solution used in each of the 'second pickling process' (S130) and the 'decontamination process' (S150) is titrated such that the pH is equal to the pH of the washing solution first introduced into the first pickling process . The re-titrated pickling solution after use is put into the 'first pickling step' (S110) and used. The present invention has the effect of reducing the amount of the secondary radioactive waste by reducing the amount of the waste liquid after washing the uranium contaminated soil through such a process.

In addition, the uranium dissolved in the filtrate after the first acid pickling and separation of fine soil is selectively removed by adsorption, desorption, precipitation and filtration using an ion exchange resin. The present invention provides a method for treating uranium-contaminated soil capable of reducing the amount of secondary radioactive waste by regenerating the ion exchange resin used in the selective removal of uranium (S160, S170) and recycling it to the uranium adsorption process (S160) do.

According to the invention, in the decontamination method of uranium contaminated soil by using the electric power, in the pickling process of the existing uranium contaminated soil, the micro-soil is separated from the remaining soil of the remaining size, Can be reduced to 1/3 or less and the decontamination time can be shortened. In addition, the amount of secondary radioactive waste can be reduced by more than 90% by adsorbing and desorbing dissolved uranium in the filtered solution after the first washing, and then removing it by sedimentation.

In addition, when the acid washing reactor is heated and sodium chlorate is added as an oxidizing agent, uranium decontamination efficiency can be increased by 4.8 times or more as compared with the case where no oxidizing agent is added at room temperature.

1 is a flowchart of a decontamination process of an improved uranium-contaminated soil according to an embodiment of the present invention.
FIG. 2 is a module diagram for a decontamination treatment of an improved uranium contaminated soil according to an embodiment of the present invention.
FIG. 3 is a graph comparing uranium decontamination performance according to acid washing treatment conditions according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

The present invention provides a high-efficiency uranium contaminated soil decontamination method by a uranium decontamination method using an ion exchange resin and a regeneration method of an ion exchange resin used in an uranium decontamination process from a pickling solution generated in pickling of soil contaminated with uranium.

More specifically, as an embodiment of the present invention, the electrokinetic uranium contaminated soil treatment method is intended to decontaminate uranium contaminated soil, and it is an object of the present invention to improve the process of electro- It is possible to decontaminate only the fine soil in the entire treated sample by the electrochemical treatment, thereby greatly reducing the sample to be electrochemically treated.

According to another embodiment of the present invention, there is provided a method of treating electrodynamic uranium contaminated soil, comprising the steps of raising the pH of the solution from 7 to 9 to precipitate uranium from the washing liquid discharged after washing the contaminated soil, (IGNASI CASA, Geochimica et Cosmochimica Acta, Vol. 62, No. 13, pp 2223-2231), and then uranium in the washing liquid was adsorbed on the ion exchange resin, followed by uranium desorption, precipitation and filtration, Can be selectively removed.

The method for treating uranium contaminated soil according to another embodiment of the present invention includes a step of restoring the adsorption activity of the ion exchange resin. This process is a process in which the ion exchange resin used after the uranium absorption / desorption process is immersed in a sodium hydroxide (NaOH) solution and stirred.

The process of treating the uranium contaminated soil of FIG. 1 includes the steps of 'first pickling' (S110) and 'second pickling' (S130) after putting the contaminated soil into the hopper, S120, and S140).

In addition, the micro-soil separated in the primary and secondary pickling steps of FIG. 1 is directly fed to the copper electroplating process (S150), and the uranium-contaminated soil having a grain size larger than that of the micro- S130), the decontamination period of the entire uranium-contaminated soil can be shortened.

The dissolved uranium component in the filtrate of the washing solution generated in the primary pickling process is adsorbed at the active site of the ion exchange resin and then selectively removed by desorption, precipitation and filtration from the ion exchange resin. At this time, the ion exchange resin used is recycled and reused in the uranium adsorption process (S160), thereby reducing the secondary radioactive waste to 1/10 or less.

In order to achieve the above object, the present invention provides a method for treating uranium-contaminated soil as a module as shown in FIG. 2 is composed of a pickling module S220, a uranium selective removal module S230 using an ion exchange resin, and an ion exchange resin regeneration module S240 to obtain a high decontamination efficiency. The acid pickling module S220 is a module for performing the primary pickling process S110 and the secondary pickling process S130 and the micro-soil separation processes S120 and S140 and the copper electroplating process S150 shown in FIG. 1 . The method for treating a waste solution of uranium-contaminated soil according to the present invention is configured to include a uranium selective removal module (S230) and an ion exchange resin recovery module (S240) using an ion exchange resin. Examples 1 to 3 were specifically described.

Example 1: Uranium contaminated soil pickling module

<Improved washing process of uranium contaminated soil>

As shown in Fig. 1, "the primary pickling" (S110) process constituting the uranium contaminated soil processing method according to an embodiment of the present invention ⅰ) uranium contaminated soil 500g, water 500g and 1 M sulfuric acid (H ₂ SO ₄ ) and 5 g of an oxidizing agent are put together in a reaction vessel and the above samples are washed at a fixed temperature; Ii) removing the suspension separately from the reaction tank of step i); Iii) sieving the pores in a 0.1 mm sieve to separate the fine soil from the suspension, and filtering through a 0.02 mm pore filter press; iv) transferring the filtrate to the 'uranium selective removal module using ion exchange resin' (S230).

The step i) includes a step of mixing water and sulfuric acid into the reaction tank so as to have a pH of 0.3 or more and a pH of 0.7 or less. The washing solution discharged from the whole process is re-titrated to have a pH value between 0.3 and 0.7, Primary pickling 'step (S110). Also, the i) step includes a method of using sodium chlorate (NaClO ₃ ) as an oxidizing agent. The step i) includes a step of washing by a method of immersing in a hot water boiler set at 70 ^° C for 3 hours.

Uranium Residual Concentration in Uranium Contaminated Soil by Pickling Reactor Temperature evaluation Pickling bath temperature ( ^o C) uranium
Contaminated soil (g) Ion-removing water
(mL) Sulfuric acid
1M (ml) Residual uranium concentration in soil (mg / L) Decontaminated
uranium
density
(mg / L) Before pickling After pickling T1 Room temperature 100 150 7 235 198 37 T2 70 100 150 7 235 131 104

In the results of Table 1, when the temperature of the pickling bath was adjusted at room temperature and 70 ° C respectively, the concentration of residual uranium in the soil after acid pickling was compared with that of the decontaminated uranium at pH 70 Which is the result of the analysis.

Meanwhile, as described above, the i) step includes adding sodium chlorate (NaClO ₃ ), which is an oxidizing agent, in treating the uranium-contaminated soil in the primary pickling step (S110) using sulfuric acid. Table 2 shows the effect of uranium decontamination by oxidant addition at room temperature and 70 ^° C.

Uranium residue concentration in uranium contaminated soil evaluation Pickling
Reactor temperature (℃) uranium
Contaminated soil (g) Ion-removing water
(mL) Sulfuric acid
1M (ml)
Sodium chlorate (g) Residual uranium concentration in soil (mg / L) Decontaminated
uranium
density
(mg / L) Before pickling After pickling T3 Room temperature 100 150 7 One 235 91.6 143.4 T4 70 100 150 7 One 235 55.6 179.4

In Table 2, the concentration of uranium decontaminated in the soil is controlled by the temperature of the pickling bath at 70 ^° C, the result of T4 in Table 2 with 1 g of sodium chlorate added per 100 g of contaminated soil, and Table 1 without sodium chlorate It was confirmed that the decontamination effect was increased by 73% or more as compared with the T2 result. In addition, the evaluation results of T1 in Table 1, which was decontaminated without addition of sodium chlorate at the same temperature as the T3 evaluation result in Table 2, were compared by adding 1 g of sodium chlorate per 100 g of contaminated soil in a pickling reaction tank at room temperature As a result, it was confirmed that the decontamination effect was increased by 288% or more when sodium chlorate was added.

Based on the results of Tables 1 and 2, the temperature of the pickling bath and the amount of uranium decontaminated when sodium chlorate was added are shown in FIG. 3 in comparison with FIG.

As shown in FIG. 3, the evaluation result of T1 without addition of sodium chlorate at room temperature shows that the concentration of uranium decontamination is 4.8 times or more as compared with the evaluation result of T4 in which the pickling bath temperature is 70 and 1 g of sodium chlorate is added I could confirm.

From the above results, it can be confirmed that the combination of the temperature control factor in the pickling bath and the acidity changing composition factor by addition of the oxidizing agent has a synergistic effect on the decontamination performance of the uranium contaminated soil.

As shown in FIG. 1, a secondary acid washing step (S130) constituting a method of treating a uranium contaminated soil according to an embodiment of the present invention is to wash soil excluding fine soil in a first washed soil. In the first and second pickling process, the separated fine soils are transferred to the electric furnace, and the decalcified fine soils are decontaminated in the same manner as the coarse grain soils.

Meanwhile, the primary washing liquid transferred to the uranium adsorption process (S160) using an ion exchange resin is selectively adsorbed and removed from the uranium using the ion exchange resin, and then transferred to be used in the secondary acid washing process.

At this time, the concentration of uranium contained in the washing liquid discharged from the secondary washing liquid and the copper is very low as compared with the primary washing liquid. The entire amount of the discharged cleaning liquid is treated as radioactive waste, thereby increasing the environmental and economic burden of the treatment.

Accordingly, in order to reduce the amount of the washing liquid, the washing liquid discharged from the 'copper electroplating process' (S150) and the washing liquid discharged from the 'secondary pickling' (S130) And transferred to the process for reuse.

In this case, the pH value of the washing solution introduced to be reused in the 'primary pickling' (S110) process is determined by decontamination of the uranium contaminated soil in the 'copper electroplating process (S150) process and the' secondary pickling process (S130) . Therefore, the washing solution to be reused is reused as water and sulfuric acid so as to have a pH value between 0.3 and 0.7, which is the pH operating condition of the 'primary pickling' (S110) process.

<Analysis of treatment efficiency of uranium contaminated soil>

In order to analyze the components of the washing solution treated through the 'primary pickling' (S110) process and the 'secondary pickling' (S130) process of FIG. 1 showing the improved uranium contaminated soil treatment system, the following measurements Respectively.

The uranium radiation dose was measured by using MCA (Multi-Channel Analyzer), which is an analyzer of HPGe Gamma-ray spectroscopy system (GC2018, Canberra, USA), in a 50 ml QCY48 standard container manufactured by Korea Research Institute of Standards and Science Respectively.

Meanwhile, the residual uranium concentration in the pickling solution was measured using an inductively coupled plasma atomic emission spectrometer (ICP-AES, JY Ultima-2C, Jobin Yvon, France). Table 3 shows the above-mentioned uranium radiation dose and ICP-AES analysis results.

The radiation dose of soil contaminated with uranium and the residual uranium concentration sample Radiation dose (Bq / g) Soil weight (g) Uranium residual concentration (mg / L) pH Soil before washing 35 500 Soil after washing 0.95 345 Primary washing solution 1220 0.8 Secondary washing solution 179 0.4

From the results shown in Table 3, about 30% of the fine soil was removed through two sulfuric acid washing steps, and the radiation dose to the soil of the remaining large particles was 0.95 Bq / g, .

The concentration of uranium in the solution was 1,220 mg / L. The concentration of uranium detected in the second washing solution was 179 mg / L. 6.8 times higher value of uranium was detected.

As a result, in the soil treated with uranium contaminated soil, the soil subjected to the first pickling process has a higher level of radioactivity than the self-disposal level of the soil itself, and the uranium content in the washing liquid remains high. It was confirmed that an additional treatment process had to be added.

When the concentration of the washing solution was compared, it was confirmed that the uranium removal rate of the soil was significantly lowered to 14.7% than that of the first acid washing step in the second acid washing step.

Example 2: Selective removal module of uranium using ion exchange resin

<Selection of Uranium Extraction Method>

The method of extracting uranium from the pickling solution discharged from the first and second pickling (S110, S130) and copper electroplating (S150) processes includes a method using an ion exchange resin such as a cation exchange resin and an anion exchange resin, There is a method using an extraction method.

First, it is known that as the anion exchange resin ^{IRA 910 (AMBERLITE TM, ROHM and} HASS社) and ^{AG ® 1 × 8 (Bio-} Rad社, 100 ~ 200 mesh) and a Strong Anion Exchange Resin The uranium extraction characteristics. However, as an embodiment of the present invention, uranium was extracted from the pickling solution of uranium contaminated soil using IRA 910, and as a result, the decontamination effect by the anion exchange resin could not be obtained. These results indicate that the rate of formation of uranyl sulfate anion compounds having a molar ratio of -2 to -4 is low or is due to disturbance of sulfate ion depending on the conditions of the solution.

The concentration of residual uranium in the acid washing solution discharged from the 1st to 4th step of the fractional extraction process was measured in Table 4, after dissolving Alamine 336 (tri-octyl / decyl amine) Respectively.

From the results in Table 4, it can be seen that the concentration of residual uranium in the pickling solution is not significantly different from the concentration of uranium in the pickling solution after the first extraction step when the pickling solution pH is 0.4. The same results were obtained when sodium hydroxide (NaOH) was added to the pickling solution to adjust the pH to 0.9.

Decontamination Effect of Uranium Contaminated Soil by Solvent Extraction Method Alamin 336 concentration
(M) 1-Dodecanol
(wt%) EXXSOL (mL) Acid pickling solution Uranium concentration in acid wash (mg / L) Residual uranium concentration in washing solution after primary extraction (mg / L) Residual uranium concentration (mg / L) in washing solution after fourth extraction pH Volume
(mL) 0.05 3 5 0.4 50 721 724 722 0.05 5 5 0.4 50 721 720 690 0.15 5 5 0.9 50 721 671 - 0.15 5 15 0.9 50 721 687 -

In the present invention, The removal of uranium from the anion exchange resin and the acid extraction solution using the solvent extraction method could not be achieved through the evaluation results. The removal effect of uranium using an amphoteric ion-exchange resin was evaluated and will be described in detail in Examples described later.

<Selective Removal Process of Uranium from Washing Solution>

As an embodiment of the present invention, the process for selectively removing only uranium from the waste liquid discharged from the primary pickling step (S110) of FIG. 1 constituting the method of treating uranium contaminated soil comprises the steps of: i) A step (S160) of selectively adsorbing and removing uranium ions; Ii) a step (S170) of desorbing uranium by collecting uranium-adsorbed ion exchange resin from the i) process; Iii) a step (S180) of precipitating uranium from the uranium desorption liquid resulting from the ii) process; and iv) a step (S190) of recovering the precipitated uranium.

The ion exchange resin of the above-mentioned step (S160) may be an amphoteric ion exchange resin.

The ion exchange resin used in the step of introducing the ion exchange resin to selectively adsorb and remove uranium ions in the (i) step (S160) may be an amphoteric ion exchange resin having a porous structure. It is preferable to use S-950 (Amino phosphonic chelating resin) of Purolite, which is one of amphoteric ion exchange resins.

The uranium selective removal module S230 using the ion exchange resin of the present invention

i) 30 g of S-950 was injected into 300 mL of the primary washing solution collected from Example 1, stirred for 3 hours, and uranium adsorbed S-950 from the primary washing solution was filtered with filter paper (Whatman 4) (S160);

Ii) After 20 g of the recovered uranium-adsorbed S-950 resin was dried at room temperature, 200 mL of a 0.5 M sodium carbonate solution (Na ₂ CO ₃ ) was stirred at 60 ^° C for 3 hours, A step of desorbing uranium from 950 (S170);

Iii) a step (S180) of precipitating uranium by adding nitric acid (HNO ₃ ) or sulfuric acid (H ₂ SO ₄ ) to the desorption solution of ii), adjusting the acidity of the sample in the reaction tank to pH 3 and allowing it to stand for 12 hours; And

Iv) And a step (S190) of recovering uranium after filtering the solution having precipitated uranium of iii).

<Selective Uranium Removal Efficiency Analysis Using S-950 Ion Exchange Resin>

The uranium selective removal module (S230) using the ion exchange resin of FIG. 1 showing the improved uranium contaminated soil treatment method includes a uranium adsorption process (S160); a uranium desorption process (S170); A uranium precipitation step (S180), and a uranium recovery step (S190).

Table 5 shows changes in uranium concentration through uranium adsorption, desorption, and precipitation processes of the sample treated through the uranium selective removal module 230.

Uranium concentration due to adsorption, desorption, and precipitation of uranium from the washing solution sample Uranium concentration (mg / L) Before the adsorption, 671 Residual concentration in solution after adsorption 10 Concentration of desorption liquid 650 After the uranium precipitation reaction
The residual uranium concentration in the filtered solution nitric acid 3 Sulfuric acid 10

From the results shown in Table 5, the difference between the concentration of the primary washing liquid before the adsorption and the residual concentration of uranium in the washing liquid after adsorption was 661 mg / L when the S-950 resin was used, and the desorbed uranium desorbed from the ion- Of uranium was 650 mg / L.

From the above results, it can be seen that the selective uranium removal module using the ion exchange resin of the present invention desorbs 98.3 wt% of uranium from the ion exchange resin from the U-absorbed S-950 resin and selectively removes uranium from the S- The efficiency was confirmed to be very high.

From the above results, it can be confirmed that the uranium removal module using the ion exchange resin of the present invention is configured to enhance decontamination efficiency against uranium contaminated soil.

Example 3: Regeneration module of ion exchange resin

<Regeneration of S-950 resin after uranium adsorption / desorption>

The regeneration module (S240) of an ion exchange resin according to an embodiment of the present invention desorbs uranium adsorbed to the ion exchange resin reaction active site without directly disposing the S-950 resin used for uranium adsorption, Reproducing method.

As an example of the ion exchange resin regeneration module S240, the regeneration module S240 of the S-950 resin is configured to regenerate the S-950 resin used in the uranium selective adsorption process (S160) and the desorption process (S170) An ion exchange resin regeneration process (S200) for desorbing residual uranium adsorbent in the resin by putting it in 0.5 M sodium hydroxide (NaOH) regeneration solution to saturate all reaction active sites in the resin; Ii) washing the desorbed S-950 resin with deionized water (8-10 MΩ) three to four times.

<Analysis of uranium adsorption performance of regenerated S-950 resin>

The uranium adsorption performance of the S-950 resin regenerated from the regeneration module of the ion exchange resin of the present invention through the regeneration step was analyzed as follows.

First, 2 g of S-950 resin was added to 200 mL of the washing solution, and the uranium adsorption and desorption process was carried out in the same manner as in Example 2.

 In the next step, the resin with desorbed uranium was stirred for 10 minutes with 20 mL of a 0.1M sodium hydroxide (NaOH) solution, an example of an ion exchange resin regeneration solution. After filtration of the stirred solution, 20 mL of distilled water was used to wash the S-950 resin. This recycled resin was placed in the primary washing solution of Example 1 and a uranium adsorption process was performed. The concentration of uranium in the washing solution before and after the adsorption process was analyzed and is shown in Table 6.

Analysis of uranium adsorption activity of S-950 resin sample Residual uranium concentration (mg / L) Uranium concentration removed (mg / L) Soil washing solution before adsorption 437 - Using the new S-950 resin
After the adsorption process, 323 114 Using regenerated S-950 resin
After the adsorption process, 296 141

Table 6 shows the results of uranium decontamination using unused S-950 resin and regenerated S-950 resin. As a result of the comparison, the uranium concentration removed by the regenerated S-950 resin is 6% higher than the uranium concentration removed by the new S-950 resin, so that the ion exchange resin regeneration module is suitable for applying the process of FIG. Efficiency.

&Lt; Comparison of amount of secondary waste generated by precipitation treatment method of waste liquid and ion exchange resin method >

 The conventional uranium decontamination method corresponding to the step of absorbing uranium (S160) with an ion exchange resin according to an embodiment of the present invention includes a first pickling step (S110), a second pickling step (S130) (CaO), sodium hydroxide (NaOH), or potassium hydroxide (KOH), which are basic reagents, to the washing liquid discharged from the treating step (S150) to adjust the pH to a pH range where uranium is precipitated.

In Example 1 of the present invention, after mixing the primary washing solution, the secondary washing solution and the copper washing solution, 200 mL of the sample was collected from the whole solution. Potassium hydroxide (KOH) was added dropwise to the aliquots to adjust the pH to 9 and left at room temperature for 3 days to precipitate uranium. After the uranium precipitated solution was filtered using filter paper, the dry weight of the precipitate was measured. The sedimentation amount of the resulting precipitate was calculated by the following equation.

(%) = (Precipitation weight / weight of uranium contaminated soil of coarse particles) x (total cleaning fluid volume / volume of cleaning fluid used) x 100 (Equation 1)

From the analysis of the sediment amount as described above, it was confirmed that uranium precipitate corresponding to about 8 wt% of the coarse-grained uranium-contaminated soil except fine soil was obtained. On the other hand, when the ion exchange resin was used, it was confirmed that the uranium adsorbing property of the regenerated S-950 was excellent by obtaining the uranium precipitate having a low measurement level.

Claims (9)

i) a step of pickling the uranium contaminated soil;
Ii) separating fine soil and coarse particles from the soaked contaminated soil of step i);
Iii) subjecting the micro-soil of step ii) to an electro-treatment;
Iv) removing uranium from the filtrate of the washing solution used in the pickling step of the i) step using an ion exchange resin;
V) regenerating the ion exchange resin used in the step iv); And
Vi) titrating the acid pickling solution used in the step iii) and transferring it to the step i).
Composite copper soil treatment method
The method according to claim 1, wherein the step (i)
I) a step of separating the contaminated soil into a reaction tank, washing the mixture with a mixture of water and sulfuric acid, and then immersing it in a solution; and
Ii) sieving a 0.1 mm sieve to separate the fine soil from the reactor suspension, and filtering through a 0.02 mm pore filter press
Composite copper soil treatment method
The method according to claim 1, wherein the step (iv)
I) a step of selectively adsorbing and removing uranium ions after putting the ion exchange resin into a treatment tank;
Ii) recovering uranium-adsorbed ion exchange resin from the step i) to desorb uranium;
Iii) a step of precipitating uranium from the uranium desorption solution; And
And iv) recovering the precipitated uranium in the step iii).
Composite copper soil treatment method
The method according to claim 1, wherein the step (v)
I) introducing the ion exchange resin after use into the washing liquid;
Ii) desorbing the residual uranium adsorbent in the resin by saturating all reaction active sites in the resin; And
And iii) washing the S-950 resin desorbed with uranium with deionized distilled water.
Composite copper soil treatment method
The method according to claim 1, wherein the step (v)
Characterized in that an amphoteric ion-exchange resin is used
Composite copper soil treatment method
3. The method according to claim 2, wherein the i)
Characterized in that sodium chlorate (NaClO ₃ ) is added
Composite copper soil treatment method
3. The method according to claim 2, wherein the i)
Characterized in that it is washed by bathing at 70 ^o C
Composite copper soil treatment method
The method according to claim 3, wherein the i)
Characterized in that a macroporous phosphoric acid amino-chelate resin is used
Composite copper soil treatment method
A pickling module comprising a step of picking up the uranium-contaminated soil from the pickling solution and sorting the particle size; Electrokinetic decontamination of uranium; A uranium removal module using an ion exchange resin capable of selectively removing only uranium from pickling waste; Comprising a module for regenerating uranium-depleted ion exchange resin by dipping in a sodium hydroxide solution
Complex copper electroplating device

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