A method for preparing radioactive waste resin wet oxidation waste liquid

Abstract

The present invention relates to a method for modulating waste liquid of radioactive waste resin by wet oxidation. By adopting the method provided by the present invention, the property that the temperature of the reaction system is increased by the heat released by the acid-base neutralization reaction during the modulation process, and the high-speed stirring of the high-speed disperser can be utilized to reduce the viscosity of the system, thereby shortening the reaction time of the slow reaction stage in the existing related technology, thereby solving the problems of slow reaction speed and long reaction time in the slow reaction stage. The method described in the present invention adopts different rates to add different amounts of modulators in different reaction stages to shorten the reaction time and accurately control the modulation end point; and adopts the combined use of batch quantitative addition of the modulator and online detection of the acidity meter to ensure the accuracy of the modulation end point. At the same time, the method provided by the present invention has the advantages of simple process and convenient operation, can quickly and accurately reach the modulation end point, and is particularly suitable for the modulation of waste liquid with high acidity and high viscosity.

Description

Technical Field

[0001] The invention belongs to the technical field of radioactive waste treatment, and in particular relates to a method for preparing radioactive waste resin wet oxidation waste liquid. Background Art

[0002] The safe treatment of radioactive waste resin containing organic matter is one of the difficulties and hot spots in the current domestic radioactive waste management.

[0003] At present, the country is carrying out research on inorganic volume reduction treatment technology and equipment for radioactive waste resins, including wet oxidation, supercritical water oxidation, steam reforming, etc. Among them, the wet oxidation method has the advantages of low reaction temperature (about 100°C), normal pressure reaction, no corrosive gas production, and almost no radioactive nuclides in the tail gas, which can effectively oxidize organic waste resins into small organic molecules or even inorganic substances. In the process of treating waste resins by wet oxidation, the stabilization treatment process of the oxidation residual liquid requires that the oxidized waste liquid be evaporated and concentrated and then modulated from acid to neutral or weakly alkaline. In response to this demand, the inventors, taking into account the problems of high acidity of the waste liquid after evaporation and concentration and high viscosity of the waste liquid during modulation in the existing related technologies, intend to design a method for modulating radioactive waste resin oxidation waste liquid to solve the problems of long modulation process, difficult to grasp the end point, and uneven waste liquid during the modulation process. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for modulating radioactive waste resin wet oxidation waste liquid, so as to shorten the reaction time of the slow reaction stage in the prior related technology, thereby solving the problems of slow reaction speed and long reaction time in the slow reaction stage, and at the same time achieving the goal of quickly and accurately reaching the modulation end point.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a method for preparing radioactive waste resin wet oxidation waste liquid, the method comprising the following steps:

[0006] S1. Metering and conveying waste liquid: adjusting the conveying rate of the metering pump and controlling the conveying time to control the amount of waste liquid entering the preparation container;

[0007] S2. Calculate the total amount of modulator added: determine the pH value at the modulation endpoint and calculate the total amount of the modulator added;

[0008] S3, adding the first stage modulator: adding the first stage modulator to the modulation container under high-speed stirring conditions, and adjusting the pH value of the reaction system in the modulation container to 4-6;

[0009] S4, adding the second stage modulator: according to the change of the pH meter reading, the second stage modulator is quantitatively added to the modulation container in batches under stirring conditions until the pH value of the reaction system reaches the modulation endpoint pH value.

[0010] Furthermore, the modulation container is a standard steel barrel, and the standard steel barrel is a LID-I type steel barrel with a nominal volume of 400L.

[0011] Furthermore, the delivery rate of the metering pump is adjusted to 20-30 L / min; the delivery time is controlled to 10-15 min; and the amount of waste liquid is controlled to 250-330 L.

[0012] Furthermore, the pH value at the modulation endpoint ranges from 8 to 9.

[0013] Further, the method for calculating the total amount of the modulator added is as follows:

[0014] Total amount of modulator added = waste liquid amount × waste liquid density × modulator addition ratio;

[0015] Wherein, the amount of waste liquid = metering pump delivery rate × delivery time;

[0016] The waste liquid density ranges from 1.15 to 1.21 kg / L;

[0017] The modulator is barium hydroxide monohydrate or calcium hydroxide, and the addition ratio of the modulator ranges from 0.2 to 0.5.

[0018] Furthermore, the high-speed stirring condition refers to using a high-speed disperser as a stirring device, and the high-speed disperser continuously stirs the materials in the modulation container at a speed of 1500 to 2000 r / min for 3 to 8 minutes.

[0019] Furthermore, the amount of the first stage modulator added is 70-85% of the total amount of the modulator added.

[0020] Furthermore, the first-stage modulator is added into the modulation container via the metering tank within 2 to 5 minutes.

[0021] Furthermore, during the process of adding the second-stage modulator, the stirring condition refers to controlling the high-speed disperser to continuously stir the material in the modulation container at a speed of 700 to 1600 r / min to ensure the uniformity of the material in the reaction system.

[0022] Furthermore, the second-stage modulator is added to the modulation container in a quantitative manner in batches as follows: no more than 1 / 10 of the total amount of the modulator is added to the modulation container through the metering tank, and then stirred for 1 minute; if the pH reading of the acidometer is <8.0 at this time, repeat the above operation until the pH reading of the acidometer is ≥8.0, and the modulation end point is reached; if the pH reading of the acidometer is ≥8.0 at this time, the modulation end point is reached.

[0023] The beneficial effect of the present invention is that: the radioactive waste resin wet oxidation waste liquid modulation method provided by the present invention can utilize the heat released by the acid-base neutralization reaction during the modulation process to increase the temperature of the reaction system, and the high-speed stirring of the high-speed disperser to reduce the viscosity of the reaction system, thereby shortening the reaction time of the slow reaction stage in the existing related technology, thereby solving the problem of slow reaction speed and long reaction time in the slow reaction stage. The method of the present invention adopts different rates to add different amounts of modulators in different reaction stages to shorten the reaction time and accurately control the modulation end point; and adopts batch quantitative addition of modulators and online detection of acidity meter to ensure the accuracy of the modulation end point. At the same time, the method provided by the present invention adopts a high-speed disperser as a stirring device, and controls the speed of the high-speed disperser within the range of 700 to 2000r / min according to different stages of the modulation process to ensure the uniformity of the system material. The method provided by the present invention has the advantages of simple process and convenient operation, can quickly and accurately reach the modulation end point, and is particularly suitable for the modulation of waste liquid with high acidity and high viscosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic flow chart of the method for preparing radioactive waste resin wet oxidation waste liquid.

[0025] Figure 2 It is a schematic flow chart of the method for preparing radioactive waste resin wet oxidation waste liquid according to an embodiment of the present invention.

[0026] Figure 3 It is a schematic diagram of the pretreatment and modulation process of radioactive waste resin wet oxidation waste liquid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0028] like Figures 1 to 3As shown, this embodiment provides a method for preparing radioactive waste resin wet oxidation waste liquid, the method comprising the following steps:

[0029] S1. Metering and conveying waste liquid: adjusting the conveying rate of the metering pump according to the capacity of the modulation container, controlling the conveying time, and controlling the amount of waste liquid entering the modulation container within a certain range;

[0030] like Figure 3 As shown, the oxidation residual liquid generated during the wet oxidation process of waste resin is transported to the evaporator of the oxidation residual liquid stabilization treatment process unit, and after evaporation and concentration pretreatment, a waste liquid with a salt content of 30% to 40% is obtained. The waste liquid is transported to a modulation container through a metering pump for batch modulation treatment of the radioactive waste resin wet oxidation waste liquid.

[0031] In this embodiment, a standard steel drum is used as the preparation container, and the standard steel drum is the LID-I type steel drum in the "Low and Intermediate Level Radioactive Solid Waste Container Steel Drum" (EJ1042-2014), with a nominal volume of 400 L. The delivery rate of the metering pump is adjusted to 20-30 L / min; the delivery time is controlled to 10-15 min; and the amount of waste liquid entering the preparation container is controlled to 250-330 L.

[0032] S2. Calculate the total amount of modulator added: Calculate the total amount of modulator added according to the determined pH value of the modulation endpoint;

[0033] In this embodiment, barium hydroxide monohydrate or calcium hydroxide powder is used as a modulator; and the range of the modulation endpoint pH value is determined to be 8 to 9; according to the determined adjustment endpoint pH value, by performing an acid-base titration experiment on the waste liquid sample, the following method for estimating the total amount of the modulator added (i.e., the total amount of barium hydroxide monohydrate or calcium hydroxide added) can be obtained:

[0034] Total amount of modifier added = waste liquid amount × waste liquid density × modifier addition ratio

[0035] Wherein, the amount of waste liquid = metering pump delivery rate × delivery time;

[0036] The delivery rate of the metering pump is adjusted to 20-30 L / min; the delivery time is controlled at 10-15 min; the density range of the waste liquid is 1.15-1.21 kg / L; the addition ratio of the modulator is the addition ratio of barium hydroxide monohydrate or calcium hydroxide, and the addition ratio of barium hydroxide monohydrate or calcium hydroxide is the ratio of the total mass of barium hydroxide monohydrate or calcium hydroxide added to the total mass of the waste liquid, and the value range is 0.2-0.5.

[0037] S3. Adding the first-stage modulator: under high-speed stirring conditions, add the first-stage modulator to the modulation container in a short time, and adjust the pH value of the reaction system in the modulation container to about 4-6, thereby shortening the slow reaction stage time.

[0038] The modulator monohydrate barium hydroxide or calcium hydroxide is stored in an alkali buffer tank, and the first-stage modulator is measured out through a metering tank and added to the modulation container. In this embodiment, a high-speed disperser is used as a stirring device. Under the condition that the high-speed disperser continuously stirs the materials in the modulation container at a speed of 1500-2000r / min, the first-stage modulator is added from the metering tank to the reaction system in the modulation container within 2-5min, and the amount of the first-stage modulator added is 70-85% (mass percentage) of the total amount of the modulator added; and the high-speed disperser is kept at a speed of 1500-2000r / min to continuously stir the materials in the modulation container for 3-8min to ensure the uniformity of the materials in the reaction system.

[0039] During the modulation process, the heat released by the acid-base neutralization reaction is used to increase the temperature of the reaction system, and the high-speed stirring of the high-speed disperser is used to reduce the viscosity of the system, thereby shortening the reaction time of the slow reaction stage in the existing related technology, thereby solving the problems of slow reaction speed and long reaction time in the slow reaction stage, and quickly adjusting the pH value of the reaction system to about 4-6.

[0040] S4. Adding the second stage modulator: according to the change in the reading of the acidometer, add the second stage modulator in batches and quantitatively until the pH value of the reaction system reaches the modulation endpoint pH value.

[0041] In this embodiment, the second-stage modulator is added in batches in combination with online detection by an acidity meter (i.e., pH meter) to ensure the accuracy of the modulation endpoint; at the same time, during the addition of the second-stage modulator, the speed of the high-speed disperser is controlled to 700-1600r / min to continuously stir the materials in the modulation container to ensure the uniformity of the materials in the reaction system.

[0042] In this embodiment, the second stage modulator is added to the reaction system in a quantitative manner as follows: adding the modulator monohydrate barium hydroxide or calcium hydroxide to the modulation container through a metering tank, and controlling the amount of the modulator monohydrate barium hydroxide or calcium hydroxide added not to exceed 1 / 10 of the total amount of the modulator added, and then stirring for 1 minute; if the pH reading of the acidometer at this time is <8.0, repeat the above-mentioned operation of "adding the modulator monohydrate barium hydroxide or calcium hydroxide to the modulation container through a metering tank, and controlling the amount of the modulator monohydrate barium hydroxide or calcium hydroxide added not to exceed 1 / 10 of the total amount of the modulator added, and then stirring for 1 minute" until the pH reading of the acidometer is ≥8.0, then stop adding the modulator monohydrate barium hydroxide or calcium hydroxide, and reach the modulation end point; if the pH reading of the acidometer at this time is ≥8.0, then stop adding the modulator monohydrate barium hydroxide or calcium hydroxide, and reach the modulation end point.

[0043] The method provided in the embodiment of the present invention uses barium hydroxide monohydrate or calcium hydroxide as a modulator, and utilizes the heat released by the acid-base neutralization reaction during the modulation process to increase the temperature of the reaction system, and the high-speed stirring of the high-speed disperser to reduce the viscosity of the reaction system, thereby shortening the reaction time of the slow reaction stage in the existing related technology, thereby solving the problem of slow reaction speed and long reaction time in the slow reaction stage; at the same time, different amounts of modulators are added at different rates in different reaction stages to shorten the reaction time and accurately control the modulation end point; and the modulator is added in batches and quantitatively and the acidity meter is used in combination for online detection to ensure the accuracy of the modulation end point. This embodiment uses a high-speed disperser as a stirring device, and controls the speed of the high-speed disperser within the range of 700 to 2000 r / min according to different stages of the modulation process to ensure the uniformity of the material in the reaction system. In addition, according to the modulation target pH value of this embodiment, the mass ratio of the amount of barium hydroxide monohydrate or calcium hydroxide added to the waste liquid with a salt content of 30% to 40% after evaporation and concentration pretreatment is 0.2 to 0.5. The amount of barium hydroxide monohydrate or calcium hydroxide added as the modulator can be calculated and temporarily stored in the alkali buffer tank, and then added to the modulation container through the metering tank according to different stages of the reaction.

[0044] The method provided by the embodiment of the present invention has the advantages of simple process and easy operation. The processing time from adding the modulating agent to the modulation container to reaching the modulation end point is 20 to 40 minutes, which achieves rapid and accurate reaching of the modulation end point, and is particularly suitable for the modulation of waste liquid with high acidity and high viscosity.

[0045] The method described in the present invention is not limited to the specific embodiments described. The above embodiments are only examples of the present invention. The present invention can also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be regarded as illustrative rather than restrictive in any respect. The scope of the present invention should be described by the attached claims, and any changes equivalent to the intent and scope of the claims should also be included in the scope of the present invention.

Claims

1. A method for preparing waste liquid from wet oxidation of radioactive waste resin, characterized in that: The method comprises the following steps: S1. Metering and conveying waste liquid: adjusting the conveying rate of the metering pump and controlling the conveying time to control the amount of waste liquid entering the preparation container; S2. Calculate the total amount of modulator added: determine the pH value at the modulation endpoint and calculate the total amount of the modulator added; the calculation method of the total amount of the modulator added is as follows: Total amount of modulator added = waste liquid amount × waste liquid density × modulator addition ratio; Wherein, the amount of waste liquid = metering pump delivery rate × delivery time; The waste liquid density ranges from 1.15 to 1.21 kg / L; The modulator is barium hydroxide monohydrate or calcium hydroxide, and the addition ratio of the modulator ranges from 0.2 to 0.5; S3, adding the first stage modulator: adding the first stage modulator to the modulation container under high-speed stirring conditions, and adjusting the pH value of the reaction system in the modulation container to 4-6; S4, adding the second stage modulator: according to the change of the pH meter reading, the second stage modulator is quantitatively added to the modulation container in batches under stirring conditions until the pH value of the reaction system reaches the modulation endpoint pH value.

2. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The preparation container is a standard steel barrel, and the standard steel barrel is a LID-I type steel barrel with a nominal volume of 400L.

3. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The delivery rate of the metering pump is adjusted to 20-30 L / min; the delivery time is controlled to 10-15 min; and the amount of waste liquid is controlled to 250-330 L.

4. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The pH value at the modulation endpoint ranges from 8 to 9.

5. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The high-speed stirring condition refers to using a high-speed disperser as a stirring device, and the high-speed disperser continuously stirs the materials in the preparation container at a speed of 1500 to 2000 r / min for 3 to 8 minutes.

6. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The amount of the first stage modulator added is 70-85% of the total amount of the modulator added.

7. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The first stage modulator is added into the modulation container via a metering tank within 2 to 5 minutes.

8. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 5, characterized in that: During the process of adding the second-stage modulator, the stirring condition refers to controlling the high-speed disperser to continuously stir the materials in the modulation container at a speed of 700 to 1600 r / min to ensure the uniformity of the materials in the reaction system.

9. The method for preparing waste liquid from wet oxidation of radioactive waste resin according to claim 1, characterized in that: The second stage modulator is added to the modulation container in a quantitative manner in batches as follows: no more than 1 / 10 of the total amount of the modulator is added to the modulation container through a metering tank, and then stirred for 1 minute; if the pH reading of the acidometer is <8.0 at this time, repeat the above operation until the pH reading of the acidometer is ≥8.0, which means the modulation end point is reached; If the pH reading of the acidometer is ≥8.0 at this time, the modulation end point is reached.

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