System and method for automatically preparing uranium purification stock solution from diuranate

Abstract

The invention relates to the technical field of nuclear fuel circulation, in particular to a system and method for automatically preparing uranium purification stock solution from diuranate. The method comprises the following steps: granulating diuranate; the method comprises the following steps: automatically adding nitric acid according to a set target value, heating water to a set temperature, automatically adding granular diuranate of which the theoretical demand quantity is 90%, carrying out a stirring reaction, automatically detecting the uranium concentration and the nitrate concentration, and carrying out repeated fine adjustment according to a measurement result until the error between the uranium concentration and the target concentration is within 2%; the dissolved slurry is sequentially subjected to two-layer filtration and then is subjected to belt type filtration, and uranium purification stock solution is obtained. As long as the uranyl nitrate solubility range is within the uranyl nitrate solubility range, the target concentration of the dissolving solution can be set at will, the deviation is within 2%, the turbidity of the dissolving solution after treatment is smaller than 40 ppm, and the silica gel concentration is smaller than 10 mg / L. According to the invention, the diuranate is continuously and automatically dissolved, the production efficiency is improved, and the labor intensity and the cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear fuel circulation, and in particular to a system and method for automatically preparing uranium purification stock solution from diuranate. Background Art

[0002] At present, the nuclear fuel production process in my country is generally as follows: uranium exploration - uranium mining and smelting - uranium purification and conversion - isotope separation - uranium hexafluoride conversion - nuclear fuel component manufacturing. At present, my country's uranium mining and smelting system adopts a wet recovery process, and the main process is leaching - ion exchange or extraction of uranium by leachate enrichment - precipitation of uranium qualified liquid to prepare diuranate products. The uranium purification process currently adopted in my country is mainly the extraction method, which dissolves diuranate with nitric acid to form uranyl nitrate solution, and then extracts it with TBP kerosene solution to separate and remove impurity elements, and obtain nuclear pure products.

[0003] However, in my country's current industrial production, the dissolution process of uranium concentrate is manually operated, with a harsh operating environment, high labor intensity and low efficiency. In the long run, automated dissolution will become a future development trend due to its advantages such as relatively constant composition of the dissolving liquid, low labor intensity of operators and environmental friendliness. In addition, due to the relatively high water content of diuranium salt, its own viscosity, poor fluidity and difficulty in controlling the addition of materials, it brings certain challenges to the realization of the automatic process, and there is currently a lack of effective technical means.

[0004] In addition, the use of monitoring instruments is essential to achieve automated dissolution of solutions. However, the development of instruments for the nitric acid-sodium nitrate-uranyl nitrate system in my country has hardly been carried out due to its small scope of application. Moreover, there is a lack of necessary practical measures to resolve various actual interference factors during the use of similar instruments, resulting in slow progress in the actual application of such instruments.

[0005] The extraction process of uranium purification not only has certain requirements on the uranium concentration and nitrate concentration of the diuranate nitric acid solution, but also has very strict requirements on the turbidity and colloid content of the solution. The turbidity usually needs to be controlled below 50ppm, otherwise the solution will cause emulsification during the extraction process, resulting in the inability to carry out the extraction and purification process normally. At present, plate and frame filter presses are basically used for filtration, but plate and frame filter presses have shortcomings such as acidic gas leakage and can only perform intermittent batch operations.

[0006] To sum up the above situation, there is no report on the research of the automated dissolution process of diuranate. In addition, since the enterprises engaged in related production also adopt intermittent feeding, there is no corresponding industrial practice. To a certain extent, it restricts the overall improvement of my country's uranium purification and conversion technology level. There is an urgent need to explore a new automatic dissolution process. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a system and method for automatically preparing uranium purification stock solution from diuranate, so as to realize continuous and automatic dissolution of diuranate, improve production efficiency and reduce manual labor intensity and cost.

[0008] The present invention provides a method for automatically preparing a uranium purification stock solution from diuranate, comprising the following steps:

[0009] Step 1: diuranate pelleting;

[0010] Step 2: According to the set target value, nitric acid and water are automatically added and heated to the set temperature, and 90% of the theoretical required amount of granular diuranate is automatically added. After stirring for reaction, the uranium concentration and nitrate concentration are automatically detected, and fine-tuned repeatedly according to the measurement results until the error with the target concentration is within 2%;

[0011] The automatic detection method of the solution is:

[0012] Prepare standard solutions with different nitrate and uranium concentrations, measure their absorbance and conductivity, and form a linear relationship diagram of uranium concentration-absorbance value, a three-dimensional grid diagram of uranium concentration and nitrate concentration and conductivity, and form a detection database;

[0013] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and then locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0014] Step 3: The dissolved slurry is filtered through two layers in sequence and then belt filtered to obtain a purified uranium stock solution;

[0015] The first layer is a quartz sand filter layer, and the second layer is a granular activated carbon or anthracite filter layer.

[0016] Preferably, the step 1 is specifically as follows: pressing the diuranate product into 2 mm to 5 mm particles, drying at a temperature of 100° C. to 140° C. for 1 to 5 hours, drying the moisture in the particles to below 0.2%, and setting aside for use.

[0017] Preferably, in step 2, the fine-tuning method is:

[0018] According to the automatically determined uranium concentration and nitrate concentration, if the uranium concentration is too low and the nitrate concentration is too high, granular diuranate is automatically added and dissolved for 20 to 30 minutes, and the uranium concentration and nitrate concentration are measured again; if the nitrate concentration is too low, nitric acid is automatically added to measure the uranium concentration and nitrate concentration;

[0019] Fine-tune repeatedly based on the measured concentration results.

[0020] Preferably, the belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite, with a coating thickness of 1 to 5 cm.

[0021] Preferably, the quartz sand particles of the first layer are 1 to 5 mm, and the filter layer thickness is not less than 1 m;

[0022] The particles in the second layer are granular activated carbon or anthracite filter layer with a particle size of 1 to 5 mm.

[0023] Preferably, when measuring the uranium concentration and the nitrate concentration, the solution is first cooled to 20° C. before measuring.

[0024] The present invention provides a system for automatically preparing uranium purification stock solution from diuranate, comprising:

[0025] Granulating dryer, connected to the silo;

[0026] A vibrating feeder is provided at the bottom of the silo and is equipped with a measuring scale;

[0027] A vibrating feeder feeds granular diuranate into a dissolving tank;

[0028] The dissolving tank has a conical bottom and a heating coil inside. Steam is introduced into the heating coil for heating, and the temperature is maintained at 50-80°C during the reaction.

[0029] The dissolving tank is also connected to a pump for adding nitric acid and water into the dissolving tank;

[0030] The online measuring instruments of uranium and nitrate are connected to the dissolution tank;

[0031] A controller interacts with the online measuring instruments of uranium and nitrate, monitors the measurement results of the online measuring instruments of uranium and nitrate, automatically controls the switch of the vibrating feeder and the pump, and adds granular diuranate, acid or water into the dissolving tank;

[0032] The lower part of the dissolving tank is connected with the first filter layer, the second filter layer and the belt filter in sequence.

[0033] Preferably, the dissolving tank is a trough structure, and a stirring device is arranged inside the trough structure.

[0034] Preferably, the belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite, with a coating thickness of 1 to 5 cm;

[0035] The quartz sand particles of the first filter layer are 1 to 5 mm, and the filter layer thickness is not less than 1 m;

[0036] The second filter layer is a granular activated carbon or anthracite filter layer, with particles of 1 to 5 mm.

[0037] Preferably, a constant temperature condensation device is provided between the online measuring instrument for uranium and nitrate and the dissolution tank.

[0038] Compared with the prior art, the system and method for automatically preparing uranium purification stock solution from diuranate of the present invention add the highly viscous diuranate into the dissolving tank in the form of dry particles, which is convenient for smooth feeding and metering control; adopt a new constant temperature colorimetric-conductivity online detection method to detect the uranium concentration and nitrate concentration of the dissolved solution in real time, and automatically control it, so as to accurately obtain the target concentration solution; dissolve to produce slurry, and remove insoluble matter and soluble silica gel by multi-stage filtration, so as to prepare qualified uranium purification stock solution. As long as it is within the solubility range of uranyl nitrate, the target concentration of the dissolved solution can be set arbitrarily, and the deviation is within 2%, the turbidity of the dissolved solution after treatment is less than 40ppm, and the silica gel concentration is less than 10mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram showing the structure of a system for automatically preparing a purified uranium stock solution from diuranate;

[0040] In the figure,

[0041] 1-granulating dryer, 2-silo, 3-vibrating feeder, 4-dissolving tank, 5-pump, 6-online measuring instrument for uranium and nitrate, 7-controller, 8-first filter layer, 9-second filter layer, 10-belt filter, 11-constant temperature condensing device. DETAILED DESCRIPTION

[0042] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0043] Aiming at the problems of intermittent operation, high labor intensity, low labor productivity, unstable liquid quality and poor working environment in the current diuranate dissolution process, the present invention focuses on three aspects: diuranate feeding, automatic control of the dissolution process and treatment of the dissolved liquid, and further develops a system and method for automatically preparing uranium purification stock solution from diuranate based on the idea of ​​automatic dissolution.

[0044] The embodiment of the present invention discloses a method for automatically preparing a uranium purification stock solution from diuranate, comprising the following steps:

[0045] Step 1: diuranate pelleting;

[0046] The diuranate can be easily added to the dissolving tank in the form of dry particles, which facilitates smooth addition and metering control.

[0047] Specifically, the diuranate product is pressed into 2mm-5mm particles, dried at a temperature of 100°C-140°C for 1-5 hours, and the moisture in the particles is dried to below 0.2%, and then set aside.

[0048] The step 1 is carried out in a granulating dryer, and then the granular diuranate is transported to a silo and automatically added to a dissolving tank through a vibrating feeder at the bottom of the silo. The vibrating feeder is equipped with a metering scale to measure the mass of the diuranate added.

[0049] Step 2: According to the set target value, nitric acid and water are automatically added and heated to the set temperature, which is the dissolution temperature, and the dissolution temperature is maintained at 50-80°C;

[0050] Automatically add 90% of the theoretical required amount of granular diuranate, stir and react for 2 to 5 hours, automatically detect the uranium concentration and nitrate concentration, and make repeated fine adjustments based on the test results until the error with the target concentration is within 2%;

[0051] The scope of the automatic detection is colorimetric-conductivity combined detection, and the specific detection method is:

[0052] Prepare standard solutions with different nitrate and uranium concentrations, measure their absorbance and conductivity, and form a linear relationship diagram of uranium concentration-absorbance value, a three-dimensional grid diagram of uranium concentration and nitrate concentration and conductivity, and form a detection database;

[0053] The concentration of the standard solution is set as follows:

[0054] Low concentration value: uranium concentration 100g / L, nitrate concentration 1mol / L; high concentration value: uranium concentration 400g / L, nitrate concentration 4mol / L; uranium concentration changes by 100g / L each time, nitrate concentration changes by 1mol / L each time, and the combination is performed;

[0055] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and then locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0056] Since temperature will affect the determination of density and conductivity, the dissolved solution is passed through a constant temperature condensation device before testing and cooled to a fixed temperature of 20°C before measurement.

[0057] The fine-tuning method is:

[0058] According to the automatically determined uranium concentration and nitrate concentration, if the uranium concentration is too low and the nitrate concentration is too high, granular diuranate is automatically added and dissolved for 20 to 30 minutes, and the uranium concentration and nitrate concentration are measured again; if the nitrate concentration is too low, nitric acid is automatically added to measure the uranium concentration and nitrate concentration;

[0059] Based on the measured concentration results, fine-tuning is performed repeatedly until the error with the target concentration is within 2%.

[0060] Step 3: The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0061] The first layer is a quartz sand filter layer, and the second layer is a granular activated carbon or anthracite filter layer.

[0062] Since there is still insoluble slag in the diuranate, the step 3 is used for solid-liquid separation of the dissolved solution.

[0063] The dissolved slurry is pumped into the first filter layer from the bottom of the dissolution tank. The first layer is a quartz sand filter layer to remove large particles and flocculent suspended matter. The quartz sand particles are 1 to 5 mm, and the filter layer thickness is not less than 1m. The solution that has passed through the first filter layer passes through the second filter layer to adsorb and remove most of the silica gel. The second layer is a granular activated carbon or anthracite filter layer with particles of 1 to 5 mm. After most of the silica gel is removed, the solution is belt filtered again to remove fine particles and residual silica gel. The belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite to ensure that the solution turbidity and colloid concentration meet the requirements. The coating thickness is 1 to 5 cm.

[0064] The embodiment of the present invention also discloses a system for automatically preparing uranium purified stock solution from diuranate, such as Figure 1 As shown, including:

[0065] Granulating dryer 1, connected to silo 2;

[0066] A vibrating feeder 3 is provided at the lower part of the silo 2, and the vibrating feeder 3 is equipped with a weighing scale;

[0067] The vibrating feeder 3 feeds the granular diuranate into the dissolving tank 4;

[0068] The dissolving tank 4 is a trough structure, and a stirring device is arranged inside the dissolving tank; the bottom of the dissolving tank is conical, and a heating coil is arranged inside the dissolving tank. Steam is introduced into the heating coil for heating, and the temperature is maintained at 50-80° C. during the reaction;

[0069] The dissolving tank 4 is also connected to a pump 5 for adding nitric acid and water into the dissolving tank;

[0070] An online measuring instrument 6 for uranium and nitrate is connected to the dissolution tank 5;

[0071] The controller 7 interacts with the online measuring instrument 6 for uranium and nitrate, monitors the measurement results of the online measuring instrument for uranium and nitrate, automatically controls the switch of the vibrating feeder and the pump, and adds granular diuranate, acid or water into the dissolution tank;

[0072] The lower part of the dissolving tank 4 is connected to the first filter layer 8, the second filter layer 9 and the belt filter 10 in sequence.

[0073] The belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite, with a coating thickness of 1 to 5 cm.

[0074] The quartz sand particles of the first filter layer are 1 to 5 mm, and the filter layer thickness is not less than 1 m;

[0075] The particles in the second filter layer are 1 to 5 mm.

[0076] A constant temperature condensation device 11 is provided between the online measuring instrument 6 for uranium and nitrate and the dissolution tank 4 .

[0077] In order to further understand the present invention, the system and method for automatically preparing uranium purified stock solution from diuranate provided by the present invention are described in detail below in conjunction with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0078] Example 1

[0079] The diuranate product was pressed into 2 mm particles, dried at 140° C. for 1 hour to reduce the moisture content of the particles to 0.2% for later use.

[0080] According to the set target value, nitric acid is automatically added, water is heated to the set temperature of 50°C, 90% of the theoretical required amount of granular diuranate is automatically added, and after stirring for 3 hours, the uranium concentration and nitrate concentration are automatically measured. According to the measurement results, fine-tuning is performed repeatedly until the error with the target concentration is within 2%;

[0081] The automatic detection method of the dissolving solution is:

[0082] Prepare standard solutions with different nitrate and uranium concentrations.

[0083] The low value of the standard solution concentration is: uranium concentration 100g / L, nitrate concentration 1mol / L; the high value of the standard solution concentration is: uranium concentration 400g / L, nitrate concentration 4mol / L; the uranium concentration changes by 100g / L each time, and the nitrate concentration changes by 1mol / L each time, and the absorbance value and conductivity are measured by combination, and the linear relationship diagram of uranium concentration-absorbance value and the three-dimensional grid diagram of uranium concentration, nitrate concentration and conductivity are formed respectively, so as to form a detection database;

[0084] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0085] The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0086] The first layer is a quartz sand filter layer with a thickness of 1m and particles of 1-4m;

[0087] The second layer is a granular activated carbon filter layer with particles of 1-3 mm.

[0088] The belt filter is pre-coated with a mixture of powdered activated carbon and perlite with a coating thickness of 5 cm.

[0089] Example 2

[0090] The diuranate product was pressed into 5 mm particles, dried at 100° C. for 5 hours, and the moisture in the particles was dried to 0.1% for standby use.

[0091] According to the set target value, nitric acid is automatically added, water is heated to 55°C, 90% of the theoretical required amount of granular diuranate is automatically added, and after stirring for 3 hours, the uranium concentration and nitrate concentration are automatically measured. According to the measurement results, fine-tuning is repeatedly performed until the error with the target concentration is within 2%;

[0092] The automatic detection method of the dissolving solution is:

[0093] Prepare standard solutions with different nitrate and uranium concentrations.

[0094] The low value of the standard solution concentration is: uranium concentration 100g / L, nitrate concentration 1mol / L; the high value of the standard solution concentration is: uranium concentration 400g / L, nitrate concentration 4mol / L; the uranium concentration changes by 100g / L each time, and the nitrate concentration changes by 1mol / L each time, and the absorbance value and conductivity are measured by combination, and the linear relationship diagram of uranium concentration-absorbance value and the three-dimensional grid diagram of uranium concentration, nitrate concentration and conductivity are formed respectively, so as to form a detection database;

[0095] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0096] The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0097] The first layer is a quartz sand filter layer with a thickness of 1.5m and particles of 2-5m;

[0098] The second layer is a granular activated carbon filter layer with particles of 2-5mm.

[0099] The belt filter is pre-coated with a mixture of powdered activated carbon and perlite with a coating thickness of 5 cm.

[0100] Example 3

[0101] The diuranate product was pressed into 3 mm particles, dried at 100°C for 3 hours, and the moisture in the particles was dried to 0.15% for standby use.

[0102] According to the set target value, nitric acid is automatically added, water is heated to 60°C, 90% of the theoretical required amount of granular diuranate is automatically added, and after stirring and reacting for 3 hours, the uranium concentration and nitrate concentration are automatically measured. According to the measurement results, fine-tuning is repeatedly performed until the error with the target concentration is within 2%;

[0103] The automatic detection method of the dissolving solution is:

[0104] Prepare standard solutions with different nitrate and uranium concentrations.

[0105] The low value of the standard solution concentration is: uranium concentration 100g / L, nitrate concentration 1mol / L; the high value of the standard solution concentration is: uranium concentration 400g / L, nitrate concentration 4mol / L; the uranium concentration changes by 100g / L each time, and the nitrate concentration changes by 1mol / L each time, and the absorbance value and conductivity are measured by combination, and the linear relationship diagram of uranium concentration-absorbance value and the three-dimensional grid diagram of uranium concentration, nitrate concentration and conductivity are formed respectively, so as to form a detection database;

[0106] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0107] The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0108] The first layer is a quartz sand filter layer with a thickness of 1m and particles of 2-5m;

[0109] The second layer is a granular activated carbon filter layer with particles of 2-5mm.

[0110] The belt filter is pre-coated with a mixture of powdered activated carbon and perlite with a coating thickness of 2 cm.

[0111] Example 4

[0112] The diuranate product was pressed into 3 mm particles, dried at 100°C for 3 hours, and the moisture in the particles was dried to 0.15% for standby use.

[0113] According to the set target value, nitric acid is automatically added, water is heated to 70°C, 90% of the theoretical required amount of granular diuranate is automatically added, and after stirring for 2 hours, the uranium concentration and nitrate concentration are automatically measured. According to the measurement results, fine-tuning is repeatedly performed until the error with the target concentration is within 2%;

[0114] The automatic detection method of the dissolving solution is:

[0115] Prepare standard solutions with different nitrate and uranium concentrations.

[0116] The low value of the standard solution concentration is: uranium concentration 100g / L, nitrate concentration 1mol / L; the high value of the standard solution concentration is: uranium concentration 400g / L, nitrate concentration 4mol / L; the uranium concentration changes by 100g / L each time, and the nitrate concentration changes by 1mol / L each time, and the absorbance value and conductivity are measured by combination, and the linear relationship diagram of uranium concentration-absorbance value and the three-dimensional grid diagram of uranium concentration, nitrate concentration and conductivity are formed respectively, so as to form a detection database;

[0117] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0118] The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0119] The first layer is a quartz sand filter layer with a thickness of 1m and particles of 1-4m;

[0120] The second layer is a granular activated carbon filter layer with particles of 1-4 mm.

[0121] The belt filter is pre-coated with a mixture of powdered activated carbon and perlite with a coating thickness of 1 cm.

[0122] Example 5

[0123] The diuranate product was pressed into 3 mm particles, dried at 100°C for 3 hours, and the moisture in the particles was dried to 0.15% for standby use.

[0124] According to the set target value, nitric acid is automatically added, water is heated to 79°C, 90% of the theoretical required amount of granular diuranate is automatically added, and after stirring for 2 hours, the uranium concentration and nitrate concentration are automatically measured. According to the measurement results, fine-tuning is repeatedly performed until the error with the target concentration is within 2%;

[0125] The automatic detection method of the dissolving solution is:

[0126] Prepare standard solutions with different nitrate and uranium concentrations.

[0127] The low value of the standard solution concentration is: uranium concentration 100g / L, nitrate concentration 1mol / L; the high value of the standard solution concentration is: uranium concentration 400g / L, nitrate concentration 4mol / L; the uranium concentration changes by 100g / L each time, and the nitrate concentration changes by 1mol / L each time, and the absorbance value and conductivity are measured by combination, and the linear relationship diagram of uranium concentration-absorbance value and the three-dimensional grid diagram of uranium concentration, nitrate concentration and conductivity are formed respectively, so as to form a detection database;

[0128] Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and locate the nitrate concentration in the database through the uranium concentration value and conductivity value;

[0129] The dissolved slurry enters two layers of filtration in sequence, and then is subjected to belt filtration to obtain uranium purified stock solution;

[0130] The first layer is a quartz sand filter layer with a thickness of 3m and particles of 1-4m;

[0131] The second layer is a granular activated carbon filter layer with particles of 1-4 mm.

[0132] The belt filter is pre-coated with a mixture of powdered activated carbon and perlite with a coating thickness of 3 cm.

[0133] Table 1 Conditions and results of automatic dissolution of diuranate

[0134]

[0135] The above embodiments are only preferred results of the present invention, but the present invention is not limited to the above embodiments. Within the knowledge scope of ordinary technicians in this field, corresponding combination changes can be made without departing from the purpose of the present invention.

[0136] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0137] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for automatically preparing a purified uranium stock solution from diuranate, characterized in that: The following steps are involved: Step 1: diuranate pelleting; Step 2: According to the set target value, nitric acid and water are automatically added and heated to the set temperature, and 90% of the theoretical required amount of granular diuranate is automatically added. After stirring for reaction, the uranium concentration and nitrate concentration are automatically detected, and fine-tuned repeatedly according to the measurement results until the error with the target concentration is within 2%; The automatic detection method of the solution is: Prepare standard solutions with different nitrate and uranium concentrations, measure their absorbance and conductivity, and form a linear relationship diagram of uranium concentration-absorbance value, a three-dimensional grid diagram of uranium concentration and nitrate concentration and conductivity, and form a detection database; Detect absorbance and conductivity online, obtain the corresponding uranium concentration value through the absorbance value, and then locate the nitrate concentration in the database through the uranium concentration value and conductivity value; Step 3: The dissolved slurry is filtered through two layers in sequence and then belt filtered to obtain a purified uranium stock solution; The first layer is a quartz sand filter layer, and the second layer is a granular activated carbon or anthracite filter layer.

2. The method for automatically preparing a purified uranium stock solution from diuranate according to claim 1, characterized in that: The step 1 is specifically as follows: pressing the diuranate product into 2mm-5mm particles, drying at a temperature of 100°C-140°C for 1-5 hours to reduce the moisture content of the particles to below 0.2%, and sealing them for standby use.

3. The method for automatically preparing a purified uranium stock solution from diuranate according to claim 1, characterized in that: In the step 2, the fine-tuning method is: According to the automatically determined uranium concentration and nitrate concentration, if the uranium concentration is too low and the nitrate concentration is too high, granular diuranate is automatically added and dissolved for 20 to 30 minutes, and the uranium concentration and nitrate concentration are measured again; if the nitrate concentration is too low, nitric acid is automatically added to measure the uranium concentration and nitrate concentration; Fine-tune repeatedly based on the measured concentration results.

4. The method for automatically preparing a purified uranium stock solution from diuranate according to claim 1, characterized in that: The belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite, with a coating thickness of 1 to 5 cm.

5. The method for automatically preparing uranium purified stock solution from diuranate according to claim 1, characterized in that: The quartz sand particles of the first layer are 1 to 5 mm, and the filter layer thickness is not less than 1 meter; the second layer is a granular activated carbon or anthracite filter layer, and the particles are 1 to 5 mm.

6. The method for automatically preparing uranium purified stock solution from diuranate according to claim 1, characterized in that: When measuring the uranium concentration and acid concentration, the solution is cooled to 20°C before measuring.

7. A system for automatically preparing uranium purified stock solution from diuranate, characterized in that: include: Granulating dryer, connected to the silo; A vibrating feeder is provided at the bottom of the silo and is equipped with a measuring scale; A vibrating feeder feeds granular diuranate into a dissolving tank; The dissolving tank has a conical bottom and a heating coil inside. Steam is introduced into the heating coil for heating, and the temperature is maintained at 50-80°C during the reaction. The dissolving tank is also connected to a pump for adding nitric acid and water into the dissolving tank; The online measuring instruments of uranium and nitrate are connected to the dissolution tank; A controller interacts with the online measuring instruments of uranium and nitrate, monitors the measurement results of the online measuring instruments of uranium and nitrate, automatically controls the switch of the vibrating feeder and the pump, and adds granular diuranate, acid or water into the dissolving tank; The lower part of the dissolving tank is connected with the first filter layer, the second filter layer and the belt filter in sequence.

8. The system for automatically preparing uranium purified stock solution from diuranate according to claim 1, characterized in that: The dissolving tank is a trough structure, and a stirring device is arranged inside the tank.

9. The system for automatically preparing uranium purified stock solution from diuranate according to claim 1, characterized in that: The belt filter is pre-coated with a coating of a mixture of powdered activated carbon and perlite, with a coating thickness of 1 to 5 cm; The quartz sand particles of the first filter layer are 1 to 5 mm, and the filter layer thickness is not less than 1 m; The second filter layer is a granular activated carbon or anthracite filter layer with particles of 1 to 5 mm.

10. The system for automatically preparing uranium purified stock solution from diuranate according to claim 1, characterized in that: A constant temperature condensation device is arranged between the online measuring instrument of uranium and nitrate and the dissolving tank.

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