ES2278237T3 - METHOD TO PROCESS USED EXCHANGE RESINS USED. - Google Patents

Abstract

A method for processing spent ion-exchange resins is provided by reducing the volume of the spent ion-exchange resins through a wet oxidation process and solidifying the residual wet oxidation slurry and the waste solution with high efficiency. The method comprises of using barium hydroxide as a neutralization agent to adjust pH of the reaction solution so as to drive away ammonia from the solution, and as a conversion agent to convert sulfuric acid and sulfate obtained in the reaction into barium sulfate. The process can solidify the wet oxidation residue slurry and waste solution with high efficiency. <IMAGE>

Description

Method for processing exchange resins Ionic used.

Background of the invention 1. Field of the invention

The invention relates to a method for process used ion exchange resins, and in particular, at a method to process ion exchange resins used when reducing the volume of ion exchange resins used through a wet oxidation process and when using barium hydroxide to adjust the pH of the oxidation reaction solution. He method of the invention is mainly applicable to several cleaning treatments in nuclear power plants and other fields relative.

2. Description of the prior art

The current nuclear power plants operate in based on light water reactors that use light water such as reactor coolant and as a neutron moderator. If there are ions corrosives present in the reactor water, the corrosion of the reactor will increase and activation products will be produced so that the radioactivity in the reactor system can increase up to the point that neutron savings may decrease due to lack of control of neutron capture reactions. With the purpose of solve these potential problems, they have been used extensively ion exchange resins in the nuclear power plant, including, for example, the reactor water cleaning treatment for supply demineralized reactor water; when removing from water reactor contaminants such as activation products of neutrons and fission products that escape the elements of nuclear fuel; by decreasing the oxygen content in the refrigerant; by controlling corrosion inhibitor contents and chemical additives, and the like. In addition, exchange resins ionic are also useful in wastewater treatment of The nuclear power plant.

To increase the effective surface area, Ionic powder exchange resins have also been used different to resin pearls in the nuclear power plant. The area specific surface of the ion exchange resin is about 100 times that of the ion exchange resin in pearls, and it is a kind of very fine dust. They are commonly used to coat the filter elements where, in addition to the function ion exchange, can remove small solid pearls suspended in the water.

After rejecting the exchange capacity ionic ion exchange resins or increase the radioactivity due to contamination of nuclides in resins ion exchange, ion exchange resin in beads It must regenerate. After regenerating and reusing all the times allowed, ion exchange resin in beads could Discarded as a radioactive waste. On the contrary, while the ion exchange resin could recycle a lot of solid impurities once in use, is not subject to regeneration and is discard as waste once used. According to the study conducted by US Electric Power Research Institute during 1982-1985, relating to the fraction of resins used in wet residue, the resin residue of the Water Reactor in Boiling (briefly called BWR by its initials in English) of the nuclear power plant contained 50% resin powder and 25% of resin in pearls; while the resin residue of the Reactor Water under Pressure (abbreviated PWR by its initials in English) of the nuclear power plant contained 7% resin powder and 44% of resin in pearls. In Taiwan, the resin residue of the plant BWR nuclear contained approximately 30% resin powder and approximately 11% resin in beads; while the residue of PWR nuclear power plant resin contained approximately 1% of resin powder and approximately 23% resin in pearls.

The ion exchange resin used needs be stabilized for the safety of the final device. For this one purpose, it usually solidifies with an agent such as cement, polymers, tar or the like. The effectiveness of the solidification is characterized differently by the type of used agent In general, solidification with higher polymers or tar could result in a smaller volume of products solidified However, polymers are expensive. The cost of the Operation with polymers is eventually very expensive. On the other hand, the tar gives a lower strength to the solidified product and the Product is combustible. In March 1997, an accident occurred with fire in Japan due to a solidification operation with tar, which resulted in a severe nuclear accident. The Solidification with cement is a simple and economical operation. However, while the ion exchange resin used after of solidification still has ion exchange ability such which can exchange with the calcium ion and the like in the product solidified to the point of affecting its quality. In addition, the resin solidified can absorb or release moisture and therefore experience dilation or contraction These phenomena will occur particularly in the ion exchange resin in beads that, to the severe point, it can result in dilation or cracking of the solidified product. All this will limit widely the discharge rate of the exchange resin ionic bead in the solidified product with cement such that can produce a bulky solidified product after solidification. With a view to increasing the cost of the device final, the direct solidification of the ion exchange resin Used is not cheaper.

With the treatment of exchange resins used ionic, two objectives are expected mainly as volume reduction and stabilization. The procedures for treat used ion exchange resins can be classified into two types, that is, the dry procedure and the procedure damp. The dry procedure includes incineration, vitrification and pyrolysis, while the wet process includes hydrolysis acid, oxidative hydrolysis and supercritical aqueous oxidation, etc. Therefore, the incineration procedure is the most developed Soon and it has been commercially implemented in some countries. For incineration, it is typically done in a way to mix the ion exchange resins in beads used with another residue fuel in order to control the concentration released from SO_ {x}, NO_ {x} or other hazardous gases. The control of release of radioactive nuclides is also a critical problem to resolve in the incineration procedure. Unless the discharge of volatile nuclides such as, for example, carbon 14, tritium, cesium 137 and the like can be avoided, nuclides should be removed at the beginning of the resin used to lower its radioactivity before incineration.

In the vitrification procedure, the Corrosion of the material is the main problem, while the glassy melt of ion exchange resins could exhibit strong high temperature corrosion activity. A variety of melting techniques are currently under development. in oven for vitrification. Among these, the fusion procedure in cold-walled crucible developed by SGN Company of France it has fewer corrosion problems and it is said that it could be a promising vitrification technique. La Molten Metal Technology (MMT) of the USA has developed an Extraction Procedure Quantum Catalytic (abbreviated Q-CEP by its initials in English) that, in a closed reactor, all volatile components in ion exchange resins are decomposed into simple gases with cast iron that had a strong reducing activity, while the components do not Volatile were abandoned as scum. In this way, they could obtain effective volume reduction and stabilization. He final solidified product in this procedure is a block of highly active iron containing sulfur, silicon, sodium and similar, and a special container is required to contain it. He Q-CEP system construction cost is very high and it is not economical to build a process plant with a system of small capacity In addition, the detachment in the treatment of the considerable amount of gaseous by-products such as sulfur of hydrogen and the like produced in such a procedure could be A difficult problem.

ThermoChem Inc. from the USA has developed a Vapor transformation procedure, which comprises pyrolysis of ion exchange resins under elevated temperature and, Meanwhile, it generates a useful fuel gas as fuel After the transformation. This procedure also has a severe problem of corrosion of materials, and in its future it needs Be more proven. A procedure in its initial stage of Development is the Supercritical Water Oxidation procedure (abbreviated SCWO by its initials in English). When decomposition products such as, for example, acid sulfuric, ion exchange resins are present, the supercritical high temperature water and pressure used in this procedure similarly exhibits a high degree of corrosion that makes the corrosion of the material a problem severe. This procedure is still far from practical use.

The British AEA Industry has developed with a wet oxidation process that includes carrying perform an oxidative decomposition of ion exchange resins used in pearl type when using ferrous sulfate as the catalyst, aqueous hydrogen peroxide as the oxidant and calcium hydroxide as a pH regulator at a temperature of approximately 100 ° C and pH 3-4 to break down organic components into CO 2 and H 2 O. It has been described that, to treat 40 kg of ion exchange resins, this procedure could consume 160 kg of aqueous hydrogen peroxide 50% by weight, 1 kg of acid concentrated sulfuric acid, 6 kg of calcium hydroxide, and less than 0.5 kg defoaming agent.

The ion exchange resins used generated in a nuclear power plant include the exchange resin strong acid type cationic and anion exchange resin strong base type, each possessing chemical properties different. When a wet oxidation is carried out on a cation exchange resin of strong acid type and a resin of strong base type anion exchange, the general reaction can be represented as eq. (1) and (2) respectively:

C_ {8} H_ {8} SO_ {3} + 20 \ H_ {2} O_ {2} \ rightarrow 8 \ CO_ {2} + 23 \ H_ {2} O + H_ {SO} {4}

(one)

C_ {12} H_ {19} NO + 31 \ H 2 O 2 {2} NH 4 OH + 12 \ CO 2 + 38 \ H2O

(2)

As shown in the two equations above, as the ion exchange resin is oxidized, the carbon and hydrogen constituents are oxidized in CO2 and H2O. According to equation (1) and (2), one mole of each sulfonate group and quaternary amino group content respectively in cationic and anionic exchange resins they will oxidize in one mole each of sulfuric acid and ammonium hydroxide, respectively. The sulfuric acid generated from the oxidation of cation exchange resins can, apart from increase the acidity of the solution, impart corrosive property high in the wet oxidation solution due to the presence of both sulfuric acid and hydrogen peroxide. This property corrosive may increase according to the progress of wet oxidation of Cation exchange resin. The wet oxidation of mixed cationic and anion exchange resins produces both sulfuric acid and ammonium hydroxide, and therefore, implies also the following reaction between both, that is:

H_ {SO} {4} + 2 \ NH 4 OH → (NH 4) 2 SO 4 + H 2 O

(3)

The molar ratio of sulfuric acid to ammonium hydroxide in the residual solution of wet oxidation will vary depending on the mole ratio of the resin of cation exchange to the anion exchange resin that have experienced wet oxidation. When the molar ratio of anionic / cationic exchange resin is equal to 2, hydroxide ammonium and sulfuric acid produced will form ammonium sulfate that corresponds exactly to this proportion, and the pH of the solution will increase slightly at the end of the reaction. On the other hand, according the molar ratio> 2, there will be excess ammonium hydroxide; he pH of the residual wet oxidation solution will increase significantly. On the contrary, when the molar relationship <2, excess sulfuric acid will remain and, accordingly, the pH will drop considerably.

In order to control the pH of the solution of wet oxidation, the addition of an acid or base may be necessary to adjust as desired. Typically, hydroxide of calcium or sodium hydroxide as a base. The addition of hydroxide from Calcium will convert sulfuric acid into calcium sulfate and give as result that the residual solution of wet oxidation contains mainly calcium sulfate. During the solidification of this residual solution, calcium sulfate will react with 3CaO. Al 2 O 3 present in the cement, slowly forms etringite which has low density, and converts the solidified product gradually swollen until eventually broken, and as a result, a severe quality problem is caused. For alleviate this problem, the proportion of waste load in the Solidified product can be widely discounted. This without However, it will result in a large increase in the volume of solidified residue. In addition, calcium sulfate in the solution residual tends to crystallize and agglomerate to the point of blocking transport pipes, deteriorating transport and constituting a difficulty in the operation.

Also, in the wet oxidation process of used ion exchange resins, there is an aqueous condensate generated from the reactor vapor cooling of wet oxidation in a certain amount as much as consumed H 2 O 2. This condensate can contain a certain amount of nuclides, and also inevitably contain a small amount of organic substances, which, if not treated properly, can cause excessively high concentrations of nuclides and carbon Total organic (TOC) to the point that condensation water does not It could be downloaded or reused.

In view of the above, the procedure of usual wet oxidation to treat ion exchange resins used has the biggest disadvantages that include: (1) the solution of the reaction to be treated exhibits very high corrosion property which can cause a severe corrosion attack on the material; (2) the generated liquid residue contains mainly acid sulfuric acid and its salts cannot solidify rapidly; of this mode the solidified product produced from the liquid residue it is bulky which can almost counteract the reduction effect of the volume achieved through the oxidation of exchange resins ionic.

With a view to solving the disadvantages mentioned above, after extensively studying the inventor of this patent has developed the invention in consequence.

Summary of the invention

Consequently, an object of the invention is provide a procedure to process exchange resins ionic used for the purpose of reducing the volume of resins of ion exchange by wet oxidation.

Another object of the invention is to provide a procedure for processing used ion exchange resins, in which after reducing the volume of the exchange resin ionic via wet oxidation, the wet oxidation residue and the Residual suspension solidifies with high efficiency.

According to the invention the method for processing used ion exchange resins comprises carrying carrying out the steps of claim 1. A preferred embodiment of The invention comprises the following steps:

(one)

add ion exchange resins in a sulfate solution ferrous and heat the solution with stirring at a temperature that is higher than 90 ° C and lower than the boiling point of the solution;

(2)

add aqueous hydrogen peroxide in the solution (1) and adjust the pH of the resulting mixture with sulfuric acid or barium hydroxide up to a pH range suitable for wet oxidation;

(3)

when the temperature rises to the boiling point during the addition of aqueous hydrogen peroxide, allow the solution boils spontaneously, and, allow the steam generated from this mode together with CO2 that passes through a capacitor, then collect the condensed water and carry out treatments to lower your TOC and concentration of nuclides recycle or unload the condensed water, while CO2 can be released after pass through a HEPA filter;

(4)

after adding enough aqueous hydrogen peroxide to complete wet oxidation, add barium hydroxide to the solution to increase the pH of the solution, and form sulfate barium with sulfate in the solution and at the same time, allow to escape Ammonium ion solution as ammonium hydroxide or gas ammonia;

(5)

allow ammonia hydroxide or ammonia gas to escape from the solution to pass through an ammonia dissociator to break them down into hydrogen and nitrogen gases, and take that gas hydrogen to put it in contact and react with air to form H2O, and

(6)

add solidifying agent to the suspension of (4) and mix homogeneously, and then set aside to solidify.

In an embodiment of the invention, for stabilize the wet oxidation solution gently, you choose specifically sulfuric acid as acid, while choosing specifically barium hydroxide as the basis for regulating pH, and particularly, barium hydroxide is used as the agent neutralizing With this, the following advantages can be obtained: (1) barium hydroxide can convert sulfuric acid and ammonium sulfate in barium sulfate, a solid that is insoluble and It has a high specific gravity (approximately 4.5). Display one very high stability so that, after being embedded, it can act as the aggregate in the solidified product and can so Both improve the mechanical strength of the solidified product as well. (2) Etringite would not occur to incur the problem of swelling and breakdown of the solidified product, and so both you can get a solidified product with a very good long term stability. (3) Barium sulfate formed from this Mode is a fine hard and compact particle. It is not sticky and so so much will not incur aggregation. In addition, it can be dispersed quickly in the solution so its transport, mixing and handling They can easily rush. (4) Barium hydroxide has good stabilization effects on sulfate ions, pH regulation and corrosion reduction of the residual solution.

The effectiveness of wet oxidation is closely related to the pH control of the solution reaction. The experimental results obtained from the invention indicate that the effect obtained by using barium hydroxide to regulate the pH of the wet oxidation solution is a lot better than using sodium hydroxide or ammonium hydroxide so that the pH control be stable, less consumption, and favorable to reduction of the generation of the final waste. According to the result of the invention, the pH of the oxidation solution wet is preferably controlled from 0.5 to 4 and more preferably 1 to 3 for cation exchange resins; preferably of 1.5 to 4 and more preferably 2 to 3.5 for exchange resins anionic; and preferably from 1 to 4, and more preferably from 1.5 to 3 for mixed ion exchange resins anionic-cationic. Control the pH of the solution of the reaction in an appropriate range may decrease consumption of aqueous hydrogen peroxide. The experimental results of the invention indicated that, the wet oxidation of a mixture of resins containing an equal volume ratio of resins of anionic and cationic exchange, and control the pH at approximately 2 consumes approximately 3.2 to 5 liters of 50% aqueous per liter of the ion exchange resin mixture. The lower the proportion of peroxide addition of aqueous hydrogen, the lower the proportion of peroxide consumption of hydrogen.

At the end of wet oxidation, as has been described above, the amount of the exchange resin cationic added in the reaction solution can produce the corresponding amount of sulfate as H 2 SO 4 and / or (NH 4) 2 SO 4. They can become BaSO_ {4} also through the addition of barium hydroxide as shown in the following reaction equations:

(NH 4) 2 SO 4 + Ba (OH) 2 → 2 \ NH4OH + BaSO_ {4}

(4)

H_ {SO} {4} + Ba (OH) 2 → 2 \ H 2 O + BaSO_ {4}

(5)

The ammonium hydroxide generated in the reaction above will escape the solution at pH greater than 8.5, and the proportion Exhaust will be faster as the temperature and pH increase. While the conversion is an exothermic reaction, the addition of barium hydroxide will increase the temperature and therefore It will favor the escape of ammonia. Based on the results Experimental of the invention, it has been found to be more favorable for ammonia escape when temperature and pH They are taller. In conversion, by adding the amount of hydroxide of barium required could be calculated based on the concentration of barium sulfate to the point of converting the sulfate ion properly in barium sulfate. The excess addition of hydroxide barium will increase the amount of waste, and additionally, will give an alkalinity too high to the residual solution, and will give as consequently an adverse effect on the quality of the solidified product. On the other hand, an amount added insufficient barium hydroxide will not be able to convert properly the sulfate salt in barium sulfate and will expel ammonia completely so that not only can it affect the quality of the solidified product, it will also generate and produce gas ammonia in the course of solidification or even later, producing an adverse effect on environmental hygiene.

The process according to the invention covers a perfect clean treatment of condensed water that Contains ammonia and organic carbon for the purpose of not incurring in secondary pollution. Therefore, in the generation of gas ammonia, is introduced into an ammonia dissociator where it decomposes nitrogen and hydrogen by contact with a catalyst at an elevated temperature. The hydrogen gas thus produced will oxidize in H2_O when contacting air at the outlet of the ammonia dissociator and then it will discharge along with the gas nitrogen, where the reaction involved is as follows:

2NH_ {3} \ \ frac {\ Delta} {catalyst} \ rightarrow \ N_ {2} + 2H_ {2}

(6)

2 \ H_ {2} + O_ {2} \ rightarrow \ 2 \ H_ {2} O

(7)

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For reaction (6), the base catalyst Nickel has a very good effect. According to the results experimental, nickel oxide loaded on supports SiO2 and Al2O3 is used as the catalyst, while nickel hydroxide that converts to nickel oxide at heating can be used as a catalyst precursor. When heating The catalyst bed above 600 ° C can decompose highly the ammonia gas that passes by, and decomposes almost completely at a temperature of 700 ° C. As detected in the experiment, to the temperature of 700 ° C could not detect ammonia in the gas dissociated and the NOx concentration in it is below 50 ppm.

The liquid condensate obtained by cooling the steam from the wet oxidation tank can lead nuclides, and inevitably contains small amounts of organic substances that will increase the TOC concentration (Carbon Total Organic) if they are not subject to any treatment. This can incur that the condensed water does not allow to be released or provides The difficulty of recycling. In order to solve this problem, in an embodiment of the invention, after being undergoing a TOC decrease treatment, it is allowed to pass the water condensed by a bed of ion exchange resins to Remove any possible nuclides. The experimental result demonstrated that the condensed water generated in accordance with the invention contains a TOC value between approximately several tens up to several hundred ppm. OCD decrease treatment is achieved by an advanced oxidation method or through peroxide addition. Therefore, the advanced oxidation method includes using a combination of ozone with ultraviolet light, while the peroxide includes calcium peroxide, persulfate sodium, horseradish peroxidase and the like. The results experimental indicate that both advanced oxidation method and the Peroxide addition have good effects. After this treatment, condensed water has a low TOC concentration optionally below several tens or even several ppm, and therefore it can be reused or released.

The solidifying agent used to solidify the wet oxidation liquid residue according to the procedure of the invention is specially formulated and composed of cement and pozzolanic materials such as silica smoke, ash, blast furnace slag powder, as, optionally, silicates, phosphates, and oxides or salts of calcium, silicon, magnesium, aluminum, iron, zirconium, and the like, to ensure the long-term stability and homogeneous quality as well as Improve operability. Consequently, the solidified product produced by the invention not only exhibits good strength mechanics, resistance to freezing and thawing, and water immersion resistance, but also has good long-term homogeneous stability and quality.

The present invention can provide a good solution to solve disadvantages associated with the techniques previous in which, in addition to eliminating the corrosion problem severe, demonstrates a high volume reduction effect and a quite stable control in the operation.

Brief description of the drawings

The drawings describe an embodiment illustrative of the invention that serves to exemplify the Different disadvantages and their objectives, and are as follows:

Figure 1 is a block diagram showing The methods of the invention.

Figure 2 shows the experimental apparatus for carry out the procedure to process exchange resins ionic used according to the invention.

Detailed description of the preferred embodiments

For the invention to be fully understood, The following experimental examples are illustrated in conjunction with The drawing that accompanies it.

Example 1

The experimental apparatus used in this example is It consists of, as shown in Fig. 2, a glass cup 1 of 4000 ml that can be covered with a three-mouth glass cover. Of these three mouths, the middle mouth A is provided with a Teflon 3 agitator driven by a motor 2, another mouth is used as a power port B, and another mouth is used as an outlet C. Output C communicates with a reflux tube 4, a membrane denebulizer 5, and a condenser 6. The gas mixture generated in the wet oxidation it is dismissed by the exit C, and passes through of the de-fogging membrane 5 to have water vapor contained in this mixture of gases removed as large drops of water when falling by the reflux tube 4 and flow into the reactor 7. On the other hand, as water vapor and carbon dioxide pass through the de-fogging membrane 5 in the condenser 6, the water vapor is it will cool and condense in liquid water that is collected in a bottle of reception 8 and optionally undergoes treatments such as decrease OCD, remove nuclides and the like while the dioxide from Carbon is released along with other non-condensable gases. In the condenser outlet, a Teflon tube 9 is also provided for reflux of condensed water. Teflon tube valve 9 can be opened as necessary to allow condensed water to reflux the reaction vessel to adjust the level of liquid. In Fig. 2, 10 denotes a conduit, 11 a dissociator of ammonia, 12 a heater, and 13 a thermometer, while V1, V2 and V3 denote valves.

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As wet oxidation began, 1000 ml of 0.06M ferrous sulfate was added as well as 40 ml (18.05 g dry weight) of cation exchange resin (Amberlite 200C, Dow Chemical Co.) and 60 ml (19, 88 g dry weight) of anion exchange resin (IRA-402, Dowex) in this order to the 4000 ml glass vessel 1, and then concentrated sulfuric acid was added to adjust the initial pH value of the solution to approximately 2 Then, the glass was heated on a hot plate and the engine began to stir the solution. When the temperature of the solution reached 95 ° C, a measuring pump was used to measure 50% aqueous hydrogen peroxide in the vessel at a flow rate of 12.5 ml / min. As soon as the aqueous hydrogen peroxide in the vessel was measured, the temperature of the reaction solution increased to the boiling point. The temperature was then maintained at the boiling point. If bubbles were released in the course, an appropriate amount of defoaming agent (Dow Coming Q2-3447) was added conveniently to control them. At the same time, the barium hydroxide monohydrate powder was added to adjust the pH of the solution to 1.9 ± 0.1. If the level of the solution decreased due to evaporation, the Teflon 9 tube valve was opened to reflux the water condensate to maintain a stable level. 40 ml of cation exchange resin and 60 ml of anion exchange resin were added as well as 375 ml of aqueous hydrogen peroxide every half hour. After the addition of the last batch of the resin, sufficient aqueous hydrogen peroxide was added to a predetermined amount of consumption. As the addition was completed, the reaction solution was maintained at a temperature between 98 ° C and the boiling point for 0.5 hours to allow the aqueous hydrogen peroxide to react completely.
Tamente.

The concentrated suspension obtained was poured into a separate mixing vessel and then 757 was added slowly g of solidifying agent (at a proportion of water per agent solidification of 0.76) under the stirring process. The Stirring was continued for 15 minutes to mix homogeneously, and then the suspension was poured into a mold made of polyethylene (PE) that had an internal diameter of 5 cm and a height 11 cm The suspension solidified in the mold into a product solidified cylindrical. After waiting for 28 days, the solidified product was released and both ends were cut flush to result in a sample that had both surfaces flat ends and a diameter of 5 cm and a height of 10 cm. The feature tests such as compression force, freezing and thawing, and immersion in water were carried out in the samples thus prepared according to the test methods of US Nuclear Regulatory Commision (USNCR). Table 1 and 2 list the experimental conditions and the results of the tests.

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TABLE 1 Results of wet oxidation of resins of ionic exchange in pearls

Wet oxidation conditions Volume of cation exchange resins (ml) 1400 Resin Volume anion exchange (ml) 2100 Dose of aqueous hydrogen peroxide (ml) 15575 Agent Dose defoamer (g) 17.8 Dose of Barium hydroxide used to adjust the pH (g) and release ammonia 27 Wet oxidation results TOC in ion exchange resins before wet oxidation (g) 738.01 TOC in solution after wet oxidation (g) 1.45 Proportion of organic carbon oxidation (%) 99.80

TABLE 2 Results of solidification experiments in suspension resulting from wet oxidation

Conditions and suspension results processed Monohydrate dose of barium hydroxide as a neutralizing agent (g) 485 Total weight of concentrated suspension (g) 1208 Water content of the concentrated suspension (g) 576 Conditions and results of solidification in concentrated suspension Agent Dose solidification (g) 757 Volume of solidified product (ml) 885 Product Specific Gravity solidified 2.22 Proportion in volume of IER / solidified product 3.95 Compression force after waiting 28 days (kg / cm2) 191 Force of compression after freeze and thaw test (kg / cm2) 242

The experimental results showed that no solid residue was present in the oxidation solution wet The TOC of 1.45 g as detected in the solution indicated that the proportion of TOC oxidation in exchange resins Ionic was 99.8%. The volume of the solidified product from of the wet oxidation suspension was 885 ml comprising 1 / 3.95 of the original total volume of ion exchange resins (3500 ml). The compression force of the solidified product tested according to the test method specified by USNRC it was 191 kg / cm2, and the compression force tested after Freeze and thaw test was 242 kg / cm2. Both characteristics were much higher than those specified in Technical Position in Waste Forms of USNRC and those required in Qualities Criteria for the Low Level Radioactive Waste Form of Fuel Cycle and Materials Administration of the Atomic Energy Council, Republic of China and thus indicated excellent strength mechanical, resistance to erosion and water.

Comparative example one

In the comparative example, the agents of neutralization used in the prior art were used to show the advantage of the process according to the invention About the prior techniques.

The procedure of example 1 was repeated, except that calcium hydroxide was used instead of barium hydroxide to regulate the pH of the reaction solution during the wet oxidation, as well as increasing the pH of the solution of the wet oxidation to give off ammonia. During oxidation wet, the pH of the reaction solution was maintained at 1.9 ± 0.1; while in the course of solidification, the pH of the concentrated suspension was similarly adjusted to be between 9.03 and 9.05 before mixing with the solidifying agent. Be they used the same conditions as in example 1 to adjust the water content of the suspension concentrated at the same time as the solidification as well as the proportion of water / agent solidification to be as in example 1. The results Experimental were shown in Table 3 and 4. It is seen that the weight of calcium hydroxide consumed to adjust the pH of the solution the wet oxidation was 68.2 g which was 2.5 times the amount when barium hydroxide (27 g) was used, and it was 9 times in term of number of moles This indicated that the pH control achieved at using barium hydroxide was more stable and effective than achieved when using calcium hydroxide. Regarding the effectiveness of the procession of the solidification of the concentrated suspension, the force of understanding of solidification products tested according with the test method specified by USNRC after waiting 28 days and after the freeze and thaw test indicated that solidification products did not have a mechanical force considerable. The specific gravity of the solidification product it was 1.86 which was 84% of the specific gravity (2.22) of the product solidification obtained when barium hydroxide was used. He solidification product volume was 980 ml which was 1.1 times that obtained when barium hydroxide (885 ml) was used. This indicated that the prior art procedure was less than method of the invention in aspects of pH control in the wet oxidation operation, product characteristics of solidification and the effectiveness of volume reduction.

TABLE 3 Results of wet oxidation of resins of ionic exchange in pearls

Oxidation conditions Volume of cation exchange resins (ml) 1400 Resin Volume anion exchange (ml) 2100 Dose of aqueous hydrogen peroxide (ml) 17500 Agent Dose defoamer (g) fifteen Dose of Ca (OH) 2 used to adjust the pH (g) and give off ammonia 68.2 Oxidation results wet TOC in exchange resins ionic before wet oxidation (g) 737.94 TOC in solution after wet oxidation (g) 29.62 Proportion of cationic carbon oxidation (%) 79.51

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TABLE 4 Results of solidification experiments on suspension resulting from wet oxidation

Conditions and suspension results processed Dose of Ca (OH) 2 as neutralizing agent (g) 56.8 Total weight of concentrated suspension (g) 1066 Concentrated suspension water content (g) 576 Conditions and results of the suspension solidifying concentrate Dose of solidifying agent 757 Volume of solidification product (ml) 980 Specific gravity of the solidification product 1.86 IER volume ratio / product volume of solidification 3.57 Force of understanding after waiting for 28 days (kg / cm2) 0 Force of understanding after the freeze and thaw test (kg / cm2) 28.6

Comparative Example 2

The procedure of comparative example 1 is repeated, except that NaOH was used instead of Ca (OH) 2. The experimental results are listed in Table 5 and 6. In this comparative example, the salt of Sulfate produced was Na2SO4, a highly compound soluble in water. In order to stabilize effectively Na 2 SO 4 during solidification, in addition to them conditions used in example 1 (experiment 1), was carried out another experiment (experiment 2) particularly, in which, at once the concentrated suspension solidified, the water content of 576 g to 950 g to ensure that, during solidification of the concentrated suspension, Na2SO4 no could react in its dissolved state with the agent of solidification and also form a more stable sulfate (i.e. low water solubility) to prevent Na2SO4 form crystals and then be embedded in the product of solidification that can return the stabilization reaction impossible and can also result in deterioration of the characteristics of the solidification product on contact with the humidity or with the change of temperature and humidity.

In experiment 1, the hydroxide weight of sodium consumed to adjust the pH of the oxidation solution wet was 68.7 g which was 2.54 times the amount when used barium hydroxide (27 g), and was 12 times in terms of number of moles This indicated that the pH control achieved when using sodium hydroxide was equally inferior to that achieved when using barium hydroxide The solidification product volume was 967 ml which was approximately 10% more than that obtained in the example 1 (885 ml). The strength of understanding of the products of solidification tested after waiting 28 days was 55 kg / cm2 which was much less than that obtained in example 1 (191 kg / cm2). The strength of understanding after the trial of Freezing and thawing was 32.4 kg / cm2. This indicated also that this solidification product was lower than Example 1 in aspects of pH control, the effectiveness of the reduction of volume and characteristics of the solidified product.

In experiment 2, the hydroxide weight of barium consumed to adjust the pH of the oxidation solution wet was 88.1 g that was higher than that used in experiment 1. The strength of understanding of the solidified products tested after waiting for 28 days it was 155 kg / cm2, which, although better than in experiment 1, but it was smaller than the one obtained in the Example 1 (191 kg / cm2). The strength of understanding after freeze and thaw test was 108.5 kg / cm2, although still better than experiment 1, but it was much smaller than that of solidified product obtained in example 1 (191 kg / cm2). He volume of solidification products was 1300 ml, approximately 1/3 greater than that of experiment 1, and about 1/2 larger than when using barium hydroxide in the Example 1.

When comparing the previous experiments, it can confirm that the process of the invention can obtain better results than those obtained by any prior art procedure regarding the control of reaction conditions during wet oxidation, the effectiveness of volume reduction, as well as the characteristics of the solidified product and the like.

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TABLE 5 Results of wet oxidation of resins of ionic exchange in pearls

Conditions of the wet oxidation number of experiment one 2 Volume of cation exchange resins (ml) 1400 1400 Volume of anion exchange resins (ml) 2100 2100 Dose of aqueous hydrogen peroxide (ml) 17500 17500 Dose defoaming agent (g) twenty-one 12.96 NaOH dose used to adjust the pH (g) and give off ammonia 68.7 88.1 Oxidation results wet TOC in ion exchange resins before reaction (g) 737.94 737.94 TOC in solution (g) 30.27 20.77 Organic carbon oxidation ratio (%) 80.77 93.44

TABLE 6 Results of solidification experiments in suspension resulting from wet oxidation

Conditions and suspension results processed experiment number one 2 Dose of NaOH as a neutralizing agent that gives off ammonia (g) 49.2 45.4 Weight total concentrated suspension (g) 1018 1237 Water content of the concentrated suspension (g) 576 950 Conditions and results of the solidification of the concentrated suspension Dose of agent solidification 757 1251 Volume of solidification product (ml) 967 1300 Gravity product specific solidification 1.84 1.91 IER volume ratio / product of solidification 3.62 2,692 Understanding force after waiting for 28 days (kg / cm2) 55 155 Understanding force after the freeze test and defrost 32.4 108.5 lotion (kg / cm2)

When comparing with previous experiments, it can confirm that the process of the invention can obtain better results than those obtained by the procedure of the prior art regarding the control of the conditions of reaction during wet oxidation, the effectiveness of the reduction of the volume, characteristics of the solidified product and Similar.

The following illustrated are only part of the embodiments according to the invention, and are not intended to limit the scope of the invention. When they take place in based on the description described above, the objectives Expected of the invention can be achieved. The invention therefore provides a process for processing resins of used ion exchange, which can reduce the volume of ion exchange resins used by wet oxidation and they can solidify the wet oxidation residue and the suspension with high efficiency, and therefore meets the requirement for uses commercial.

Many changes can be made and modifications in said described embodiment of the invention, by Of course, without departing from the scope of it. Agree with this, to promote the progress of science and useful techniques, the invention describes and is intended to be limited only by the scope of the appended claims.

Claims (10)

1. A method to process resins from ion exchange, comprising the following steps:

(one)

add ion exchange resins in a sulfate solution ferrous and heat the solution with stirring at a temperature between 90 ° C and the boiling point of the solution;

(2)

add aqueous hydrogen peroxide in the solution of (1) and adjust the pH of the resulting mixture with sulfuric acid or hydroxide of barium for a pH range suitable for oxidation wet

(3)

  after adding enough aqueous hydrogen peroxide to complete wet oxidation, add barium hydroxide in the solution to increase the pH of the solution, and form sulfate barium with sulfate in the solution and at the same time, allow to escape to the ammonium ion of the solution as ammonium hydroxide or gas ammonia; Y

(4)

  after concentrating the suspension obtained in (3) and cooling, mix with solidifying agent homogeneously and then remove the resulting suspension waiting for part to solidify.

2. The method as described in the claim 1, wherein said ion exchange resins in step (1) is cation exchange resin, resin of anion exchange or mixture of both. 3. The method as described in the claim 1, wherein the pH of the solution of step (2) it is in the range of 0.5 to 4 in the case of said resin of ion exchange being a cation exchange resin, in the 1.5 to 4 range in the case of anion exchange resin, and in the range of 1 to 4 in the case of a mixture of both resins of cationic and anionic exchange. 4. The method as described in the claim 1, wherein the temperature of the suspension concentrate containing barium sulfate in step (4) is by below 40 ° C at the time of adding the agent solidification. 5. The method as described in the claim 1, wherein said solidifying agent used in stage (4) is chosen from cement, silica smoke, ash, dust slag from blast furnaces, silicates, phosphates, and, optionally, oxides or salts of calcium, silicon, magnesium, aluminum, iron and zirconium. 6. The method as described in the claim 4, wherein said solidifying agent used in stage (4) is chosen from cement, silica smoke, ash, dust slag from blast furnaces, silicates, phosphates, and, optionally, oxides or salts of calcium, silicon, magnesium, aluminum, iron and zirconium. 7. The method as described in the claim 1, further comprising the following steps:

(one)

when the temperature rises to boiling point during the addition of hydrogen peroxide aqueous, allow the boil to boil spontaneously, and allow the steam thus generated together with CO2 to pass through from a condenser, then collect the condensed water and recycle or release the condensed water, while CO2 is emitted after to filter;

(2)

allow hydroxide to escape from ammonia or ammonia gas solution to pass through a ammonia dissociator to break them down into hydrogen gases and nitrogen, and contacting said hydrogen gas and reacting with air to form H2O.

8. The method as described in the claim 7, wherein the treatment to decrease the Total organic carbon (TOC) concentration of condensed water in step (1) is performed by adding peroxide, or by adding a peroxide in combination with irradiation with ultraviolet light. 9. The method as described in the claim 7, wherein the treatment to decrease the concentration of nuclides in the condensed water in step (1) is performed by passing said solution through a bed of resins of ion exchange 10. The method as described in the claim 7, wherein the operating temperature for the Ammonia decomposition is between 600ºC and 800ºC.