A method for determining the liquidus temperature of a high-level waste glass form

Abstract

The application discloses a method for determining liquidus temperature of high-level radioactive waste glass solidification body, and belongs to the technical field of glass detection. The method comprises the following steps: determining the liquidus temperature of a calibration sample by using a gradient furnace method; crushing and sieving the calibration sample to obtain a sample with a particle size greater than 150 mesh; testing the sample to obtain an extrapolated crystallization termination temperature of the calibration sample by using a DTA / DSC method with a heating rate of 30 DEG C / min or above; drawing a relationship curve by taking the extrapolated crystallization termination temperature measured by the DTA / DSC method as the abscissa and the liquidus temperature measured by the gradient furnace method as the ordinate; selecting a glass solidification body sample to be analyzed, determining the extrapolated crystallization termination temperature of the sample in the same way, and substituting the extrapolated crystallization termination temperature into the relationship curve to obtain the liquidus temperature of the sample. The liquidus temperature of the glass solidification body is calculated by substituting the extrapolated crystallization termination temperature of the glass solidification body into the relationship curve, the measurement method is quick and simple, and the test result is accurate.

Description

Technical Field

[0001] This invention relates to the field of glass testing technology, and in particular to a method for determining the liquidus temperature of high-level radioactive waste glass solidification. Background Technology

[0002] High-level radioactive waste curing is a process that involves uniformly mixing high-level radioactive waste and a glass substrate in a specific ratio under high-temperature molten conditions to form a stable glass-cured body. In this production process, the liquidus temperature of the glass-cured body is a crucial indicator. Controlling the liquidus temperature effectively prevents excessive crystallization of the glass during the high-temperature furnace melting process, thus preventing furnace blockage. Therefore, monitoring the liquidus temperature of the glass-cured body during actual production is of great significance to ensure the smooth progress of the glass-curing process.

[0003] Currently, the liquidus temperature of glass-cured bodies is mainly tested to measure the degree of crystallization of the glass during the cooling process. The main testing methods include gradient furnace method, uniform temperature furnace method, and crystal fraction extrapolation method. These methods have high accuracy in testing liquidus temperature and simulate the real situation of glass-cured bodies in high-temperature furnaces. However, they have the characteristics of large sample requirements and long holding time in actual testing, which cannot solve the needs of high-efficiency testing.

[0004] In the field of metals, differential thermal analysis / differential scanning calorimetry (DTA / DSC) is a very common method for determining the liquidus temperature. It typically uses the temperature at which solid crystallization begins during the material's transition from liquid to solid state under cooling conditions. Represented in the calorimetric curve, the liquidus temperature is the temperature at which the first inflection point of the calorimetric curve during cooling is extrapolated. However, in the field of glass-cured materials, DTA / DSC shows no thermal effect peaks during cooling, while it does show corresponding thermal effect peaks during heating, but these peaks fluctuate greatly, making it difficult to accurately determine the liquidus temperature. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for determining the liquidus temperature of high-level radioactive waste glass. This invention establishes a relationship curve between the extrapolated crystallization termination temperature obtained by the DTA / DSC method and the liquidus temperature obtained by the gradient furnace method. Then, the extrapolated crystallization termination temperature of the actual glass solidified body is substituted into the relationship curve to calculate its liquidus temperature. The measurement method is fast and simple, and the test results are highly accurate.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for determining the liquidus temperature of vitrified high-level radioactive waste liquid, comprising:

[0008] Step S1: Select various glass-cured calibration samples with different liquidus temperatures, and determine the liquidus temperature of the calibration samples respectively using the gradient furnace method.

[0009] Step S2: The above-mentioned glass-cured calibration samples are crushed, sieved, and ground into powder. After sieving, samples with a particle size greater than 150 mesh are obtained. The obtained powder samples are not subjected to any further processing, while ensuring that they are not contaminated during the preparation process.

[0010] Step S3: Set the test conditions, with the DTA / DSC heating rate above 30℃ / min, and test the sample from Step S2 to obtain the DTA / DSC curve. Analyze the DTA / DSC curve to obtain the extrapolated crystallization termination temperature of the calibration sample.

[0011] Step S4: Plot a relationship curve with the extrapolated crystallization termination temperature measured by DTA / DSC as the abscissa and the liquidus temperature measured by the gradient furnace method as the ordinate.

[0012] Step S5: Select the glass-cured sample to be analyzed, process the sample using the same crushing method as in step S2, determine the extrapolated crystallization termination temperature of the sample under the same test conditions as in step S3, substitute it into the relationship curve, and calculate the liquidus temperature of the sample.

[0013] Preferably, before step S1, the method further includes: crushing the glass-cured sample to be analyzed and performing DTA / DSC testing; by analyzing the DTA / DSC curve, the liquidus temperature range of the glass-cured sample to be analyzed is obtained. This step allows for a rough measurement of the liquidus temperature of the glass-cured sample, and a calibration sample can be selected based on this value. The liquidus temperature of the glass-cured sample to be analyzed should be covered by the temperature range of the calibration sample to obtain a reliable calibration relationship and thus accurate test results.

[0014] Furthermore, the liquidus temperature of the glass-cured calibration sample is 700℃-900℃, and the number of glass-cured calibration samples is more than three.

[0015] Preferably, the number of glass-cured body calibration samples is 5, and the liquidus temperature range includes the conventional glass-cured body liquidus temperature range, or the calibration samples are selected at several liquidus temperature points above and below the liquidus temperature of the glass-cured body to be tested.

[0016] Preferably, in step S1, calibration samples of glass-cured bodies with different liquidus temperatures are obtained by the following method:

[0017] First, different glass-cured body samples were collected, and their liquidus temperatures were determined using the gradient furnace method. A database of liquidus temperatures for different samples was established. Then, different glass-cured bodies were selected as standard samples based on the glass-cured body samples to be analyzed. The liquidus temperature of the glass-cured body to be analyzed should be covered by the liquidus temperature range of the calibration samples.

[0018] The selection of calibration samples for glass-cured bodies can be based on the liquidus temperature marked on commercially available products (gradient furnace method), or the sample preparation can be based on the liquidus temperature recorded in the literature, as long as the liquidus temperature of the selected calibration sample meets the requirements.

[0019] Furthermore, in step S3, the DTA / DSC test conditions are as follows: room temperature is raised to 1000℃, heating rate is 30℃ / min-45℃ / min, nitrogen is purged, nitrogen flow rate is 20mL / min-40mL / min, and sample weight is 20mg-30mg.

[0020] Preferably, in step S3, the DTA / DSC test conditions are: room temperature to 1000℃, heating rate 30℃ / min-35℃ / min, nitrogen purging, nitrogen flow rate 40mL / min, and sample weight 25mg.

[0021] Furthermore, the DTA / DSC curves were analyzed using NETZSCH Proteus software. Generally, the analysis software included with the testing instrument can be used for analysis, or plotting software (Origin) can be employed.

[0022] Furthermore, the relationship curve drawn in step S4 is a linear relationship: T L =AT efc +B;

[0023] Among them, T L Liquidus temperature in gradient furnace process, in °C;

[0024] T efc Extrapolated crystallization termination temperature, in °C;

[0025] A is the slope of the relationship curve;

[0026] B is the intercept of the relationship curve.

[0027] Preferably, the gradient furnace method for determining the liquidus temperature of the calibration samples specifically involves: pulverizing the glass-cured calibration samples and then placing them in a gradient furnace via a platinum boat for 24 hours or more; after the calorific value is reached, removing the glass-cured calibration samples and cooling them; and then observing the cooled glass-cured calibration samples under a microscope to determine the liquidus temperature.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method proposed in this invention aims to accurately determine the liquidus temperature of glass-cured bodies by establishing a relationship curve between the extrapolated crystallization termination temperature and the liquidus temperature. This solves the problem of large peak shape fluctuations in the thermal effect during the heating process of the DTA / DSC calorimetric curve for glass-cured bodies. This invention uses the thermal behavior of the calorimetric curve during the DTA / DSC heating process for characteristic temperature analysis, replacing existing methods that analyze the crystallization behavior curve during the cooling process.

[0030] Compared with gradient furnace / uniform furnace methods, the method proposed in this invention has the advantages of grinding the sample into powder, reducing the sample amount, improving efficiency, and reducing test costs. Compared with other DTA / DSC methods, it improves the heating rate and sample amount, and enhances the instrument response. Attached Figure Description

[0031] Figure 1 The image shown is a DTA calorimetric curve obtained in step S3 of embodiment 1 of the present invention, which corresponds to the calorimetric curve of sample 3# to be tested.

[0032] Figure 2 This is a graph showing the relationship between the extrapolated crystallization termination temperature and the liquidus temperature obtained in step S4 of Embodiment 1 of the present invention.

[0033] Figure 3 The image shown is a DSC calorimetric curve obtained in step S3 of embodiment 2 of the present invention, which corresponds to the calorimetric curve of sample 1# to be tested.

[0034] Figure 4 This is a graph showing the relationship between the extrapolated crystallization termination temperature and the liquidus temperature obtained in step S4 of Embodiment 2 of the present invention.

[0035] Figure 5 This is a DSC calorimetric curve image obtained in step S3 of Comparative Example 1 of the present invention;

[0036] Figure 6 This is a DSC calorimetric curve image obtained in step S3 of Comparative Example 2 of the present invention;

[0037] Figure 7 This is a DSC calorimetric curve image obtained in step S3 of Comparative Example 3 of the present invention;

[0038] Figure 8 This is a DSC calorimetric curve image obtained in step S3 of Comparative Example 4 of the present invention. Detailed Implementation

[0039] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0040] Unless otherwise specified, all materials and reagents used in this invention are commercially available.

[0041] This invention provides a method for determining the liquidus temperature of vitrified high-level radioactive waste liquid, and specific embodiments are as follows.

[0042] In this invention, different glass-cured body samples are first collected, and their liquidus temperatures are determined by the gradient furnace method. For details, please refer to the "ASTM C829-81(2022) Standard Implementation Procedure for Measuring the Liquidus Temperature of Glass by Gradient Furnace Method" to establish a database of liquidus temperatures for different samples.

[0043] Example 1

[0044] A method for determining the liquidus temperature of vitrified high-level radioactive waste liquid includes:

[0045] Step S1: Select calibration samples at five liquidus temperatures (750℃, 800℃, 830℃, 850℃, and 900℃) from the established database, and number them sequentially as Calibration Sample 1#, Calibration Sample 2#, Calibration Sample 3#, Calibration Sample 4#, and Calibration Sample 5#. Then, use the gradient furnace method to assign values ​​to the calibration samples. Specifically:

[0046] The glass-cured calibration samples were crushed and sieved to obtain glass-cured samples with a particle size of <30 mesh. They were then placed in a gradient furnace through a platinum boat and held at that temperature for 72 hours. After the holding time was completed, the glass-cured calibration samples were quickly removed and cooled to room temperature. The crystallization positions of the cooled glass-cured calibration samples were observed under a microscope to determine the liquidus temperature. The specific test results are shown in Table 1.

[0047] Step S2: The glass-cured body calibration samples are crushed and the crushed samples are sieved to obtain glass-cured body calibration sample powder with a particle size >150 mesh. The obtained powder sample is not subjected to any further processing, and at the same time, it is ensured that it is not contaminated during the preparation process.

[0048] Step S3: Test the prepared calibration sample powder using DTA; set the test program: heat from room temperature to 1000℃ at a rate of 35℃ / min, purge with nitrogen at a flow rate of 40mL / min, and weigh 25mg of sample.

[0049] The measured DTA calorimetric curves were analyzed using NETZSCH Proteus software, for example, calibration sample #3. Figure 1 As shown, the extrapolated crystallization termination temperature of different calibration samples was 829.6℃. The extrapolated crystallization termination temperatures of other calibration samples are shown in Table 1.

[0050] Table 1

[0051]

[0052] Step S4: Plot the extrapolated crystallization termination temperature obtained by the DTA method against the liquidus temperature determined by the gradient furnace method, using the extrapolated crystallization termination temperature as the abscissa and the liquidus temperature as the ordinate, and perform curve fitting, as shown below. Figure 2 The relationship curve is established as follows:

[0053] T L =0.975T efc +18.24; R 2 =0.9987;

[0054] Among them, T L Liquidus temperature in gradient furnace process, in °C;

[0055] T efc Extrapolated crystallization termination temperature, in °C;

[0056] Step S5: Select four glass-cured samples as test samples, process them using the same crushing method as in Step S2, and determine the extrapolated crystallization termination temperature of the samples under the same test conditions as in Step S3. Then, substitute these values ​​into the relationship curve from Step S4 to calculate the liquidus temperature T of each of the four samples. L Without verifying the accuracy of the results, the inventors further tested the four glass-cured samples using the gradient furnace method to obtain the corresponding liquidus temperatures, the results of which are shown in Table 2.

[0057] Table 2

[0058]

[0059] As shown in Table 2, the liquidus temperature obtained using the method of the present invention has an error within ±2.6℃ compared with the liquidus temperature determined by the gradient furnace method, which is small and meets the requirements of the art. Furthermore, the method of the present invention only requires plotting the working curve once. Subsequent liquidus temperature measurements can obtain liquidus temperature data that is not significantly different from that obtained by the gradient furnace method by extrapolating the crystallization termination temperature from the calorimetric curve, which is faster and more convenient.

[0060] Example 2

[0061] A method for determining the liquidus temperature of vitrified high-level radioactive waste liquid includes:

[0062] Step S1: Select calibration samples at five liquidus temperatures (750℃, 800℃, 830℃, 850℃, and 900℃) from the established database, and number them sequentially as Calibration Sample 1#, Calibration Sample 2#, Calibration Sample 3#, Calibration Sample 4#, and Calibration Sample 5#. Then, use the gradient furnace method to assign values ​​to the calibration samples. Specifically:

[0063] The glass-cured calibration samples were crushed and sieved to obtain glass-cured samples with a particle size of <30 mesh. They were then placed in a gradient furnace through a platinum boat and held at that temperature for 72 hours. After the holding time was completed, the glass-cured calibration samples were quickly removed and cooled to room temperature. The crystallization positions of the cooled glass-cured calibration samples were observed under a microscope to determine the liquidus temperature. The specific test results are shown in Table 3.

[0064] Step S2: The glass-cured body calibration samples are crushed and the crushed samples are sieved to obtain glass-cured body calibration sample powder with a particle size >325 mesh. The obtained powder sample is not subjected to any further processing, and it is ensured that it is not contaminated during the preparation process.

[0065] Step S3: Test the prepared calibration sample powder using DSC; set the test program: heat from room temperature to 1000℃, heating rate 35℃ / min, nitrogen purging, flow rate 40mL / min, and weigh 25mg of sample.

[0066] The measured DSC calorimetric curves were analyzed using NETZSCH Proteus software, for example, calibration sample #2. Figure 3 As shown, the extrapolated crystallization termination temperature of different calibration samples was 798.6℃. The extrapolated crystallization termination temperatures of other calibration samples are shown in Table 3.

[0067] Table 3

[0068]

[0069]

[0070] Step S4: Plot the extrapolated crystallization termination temperature obtained by DSC method against the liquidus temperature determined by gradient furnace method, using the extrapolated crystallization termination temperature as the abscissa and the liquidus temperature as the ordinate, and perform curve fitting, as shown below. Figure 4 The relationship curve is established as follows:

[0071] T L =0.783T efc +172.71; R 2 =0.9974;

[0072] Among them, T L Liquidus temperature in gradient furnace process, in °C;

[0073] T efc Extrapolated crystallization termination temperature, in °C;

[0074] Step S5: Select four glass-cured samples as test samples, process them using the same crushing method as in Step S2, and determine the extrapolated crystallization termination temperature of the samples under the same test conditions as in Step S3. Then, substitute these values ​​into the relationship curve from Step S4 to calculate the liquidus temperature T of each of the four samples. L To verify the accuracy of the results, the inventors tested the four glass-cured samples using a gradient furnace method and obtained the corresponding liquidus temperatures, the results of which are shown in Table 4.

[0075] Table 4

[0076]

[0077] As shown in Table 4, the liquidus temperature obtained by the method of the present invention has an error of less than ±2.6℃ compared with the liquidus temperature determined by the gradient furnace method. The error is small and meets the requirements of the art.

[0078] Example 3

[0079] In this embodiment: First, DSC testing was performed on sample 2#. The test program was set as follows: heating from room temperature to 1000℃ at a rate of 35℃ / min, nitrogen purging at a flow rate of 40mL / min, and a sample weight of 25mg. The measured DSC calorimetric curve was analyzed using NETZSCH Proteus software, and the liquidus temperature range was between 815℃ and 830℃.

[0080] Based on the above liquidus temperature range, calibration samples at four liquidus temperature points of 750℃, 800℃, 830℃, and 850℃ were selected from the established database.

[0081] The subsequent methods are the same as in Example 2.

[0082] The final calculated liquidus temperature was 824.1℃, indicating high accuracy in the test.

[0083] Example 4

[0084] In this embodiment, the test procedure is set as follows: heating from room temperature to 1000℃ at a rate of 30℃ / min, purging with nitrogen at a flow rate of 30mL / min, and weighing approximately 20mg of sample; the remaining conditions are the same as in Example 2.

[0085] Example 5

[0086] In this embodiment, the test procedure was set as follows: heating from room temperature to 1000℃ at a rate of 40℃ / min, purging with nitrogen at a flow rate of 20mL / min, and weighing approximately 30mg of sample; the remaining conditions were the same as in Example 2.

[0087] The liquidus temperatures obtained by the method of the present invention are not significantly different from those measured by the gradient furnace method. In other words, the liquidus temperatures detected by the method of the present invention are highly accurate, simple to operate, and time-saving.

[0088] To further illustrate the beneficial effects of the present invention, the following comparative examples were constructed.

[0089] Comparative Example 1

[0090] In this comparative example, the test procedure was set as follows: heating from room temperature to 1000℃ at a rate of 10℃ / min, purging with nitrogen at a flow rate of 40mL / min, and weighing approximately 25mg of sample; the remaining conditions were the same as in Example 2.

[0091] Comparative Example 2

[0092] In this comparative example, the test procedure was set as follows: heating from room temperature to 1000℃ at a rate of 20℃ / min, purging with nitrogen at a flow rate of 40mL / min, and weighing approximately 25mg of sample; the remaining conditions were the same as in Example 2.

[0093] Comparative Example 3

[0094] In this comparative example, the glass-cured body calibration sample was crushed and sieved to obtain a sample with a particle size of 50-100 mesh. The other conditions were the same as in Example 2.

[0095] Comparative Example 4

[0096] In this comparative example, the glass-cured calibration sample was crushed and sieved to obtain a sample with a particle size of 100-150 mesh. The other conditions were the same as in Example 2.

[0097] As can be seen from the calorimetric curves 5-8 of Comparative Examples 1-4 above, the curves in the figures do not have obvious inflections, and the extrapolated crystallization termination temperature cannot be identified. Comparative Examples 1-2 are due to a slower heating rate, resulting in a weaker peak effect that is not easy to observe; while Comparative Examples 3-4 are due to a larger sample particle size, resulting in a weaker peak.

[0098] In summary, this invention quantitatively determines the liquidus temperature of glass-cured bodies by establishing a relationship curve between the liquidus temperature obtained by gradient furnace method and the extrapolated termination temperature of crystallization measured by DTA / DSC method. Compared with the gradient furnace method, the method proposed in this invention requires less sample and has a faster analysis speed after curve establishment, achieving efficient measurement of the liquidus temperature of glass-cured bodies.

[0099] The above description is a preferred embodiment of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the liquidus temperature of vitrified high-level radioactive waste liquid, characterized in that, include: Step S1: Select various glass-cured calibration samples with different liquidus temperatures, and determine the liquidus temperature of the calibration samples respectively using the gradient furnace method. Step S2: The above-mentioned glass-cured calibration samples are crushed, sieved, and ground into powder, and then sieved to obtain samples with a particle size greater than 150 mesh. Step S3: Set the test conditions, the DTA / DSC heating rate is above 30℃ / min, test the sample from step S2 respectively, obtain the DTA / DSC curve, analyze the DTA / DSC curve, and obtain the extrapolated crystallization termination temperature of the calibration sample. Step S4: Plot a relationship curve with the extrapolated crystallization termination temperature measured by DTA / DSC as the abscissa and the liquidus temperature measured by the gradient furnace method as the ordinate. Step S5: Select the glass-cured sample to be analyzed, process the sample using the same crushing method as in step S2, determine the extrapolated crystallization termination temperature of the sample under the same test conditions as in step S3, substitute it into the relationship curve, and calculate the liquidus temperature of the sample.

2. The method for determining the liquidus temperature of high-level radioactive waste liquid vitrified according to claim 1, characterized in that, Before step S1, the process further includes: crushing the glass-cured sample to be analyzed and performing DTA / DSC testing; obtaining the liquidus temperature range of the glass-cured sample to be analyzed by analyzing the DTA / DSC curve; and then selecting multiple glass-cured calibration samples that include the liquidus temperature range.

3. The method for determining the liquidus temperature of high-level radioactive waste glass according to claim 1, characterized in that, In step S1, the liquidus temperature of the glass-cured calibration sample is 700℃-900℃, and the number of glass-cured calibration samples is more than 3.

4. The method for determining the liquidus temperature of high-level radioactive waste glass according to claim 1, characterized in that, In step S1, calibration samples of glass-cured bodies with different liquidus temperatures are obtained by the following method: First, different glass-cured body samples were collected, and their liquidus temperatures were determined using the gradient furnace method. A database of liquidus temperatures for different samples was established. Then, different glass-cured bodies were selected as standard samples based on the glass-cured body samples to be analyzed. The liquidus temperature of the glass-cured body to be analyzed should be covered by the liquidus temperature range of the calibration samples.

5. The method for determining the liquidus temperature of high-level radioactive waste liquid vitrified according to claim 1, characterized in that, In step S3, the DTA / DSC test conditions are as follows: room temperature is raised to 1000℃, the heating rate is 30℃ / min-45℃ / min, nitrogen is purged, the nitrogen flow rate is 20mL / min-40mL / min, and the sample weight is 20-30mg.

6. The method for determining the liquidus temperature of high-level radioactive waste liquid vitrified according to claim 4, characterized in that, In step S3, the DTA / DSC test conditions are as follows: room temperature is raised to 1000℃, the heating rate is 30℃ / min-35℃ / min, nitrogen is purged, the nitrogen flow rate is 40mL / min, and the sample weight is 25mg.

7. The method for determining the liquidus temperature of high-level radioactive waste liquid vitrified according to claim 1, characterized in that, The DTA / DSC curves were analyzed using NETZSCH Proteus software.

8. The method for determining the liquidus temperature of high-level radioactive waste glass according to claim 1, characterized in that, The relationship curve drawn in step S4 is a linear relationship: T L =AT efc +B; Among them, T L Liquidus temperature in gradient furnace process, in °C; T efc Extrapolated crystallization termination temperature, in °C; A is the slope of the relationship curve; B is the intercept of the relationship curve.

9. The method for determining the liquidus temperature of high-level radioactive waste liquid vitrified according to claim 1, characterized in that, The gradient furnace method for determining the liquidus temperature of the calibration samples is as follows: the glass-cured calibration samples are crushed and then placed in a gradient furnace through a platinum boat and kept at that temperature for 24 hours or more; after the temperature is maintained, the glass-cured calibration samples are taken out and cooled; the cooled glass-cured calibration samples are observed under a microscope to determine the liquidus temperature.

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