In-situ leaching uranium radon diffusion device and measurement method of radon release amount

Abstract

The present invention relates to a radon diffusion device for in-situ leaching of uranium and a method for measuring the radon release amount. By providing a set of radon diffusion devices for in-situ leaching of uranium to simulate the spatial environment of the pumping holes in the in-situ leaching process, the radon concentrations at different positions in this environment are collected. The effective radon diffusion coefficient is obtained based on the radon concentrations at different positions, and the radon concentration at the connection opening between the top of the pumping hole and the environment during actual operation is calculated according to the effective radon diffusion coefficient, and the radon release amount is calculated based on the radon concentration at the opening. The present invention does not require monitoring of the air radon concentration, and can directly measure the radon concentration at the connection between the surface of the pumping hole and the environment for a large number of pumping holes with similar temperature and humidity environments in the same or different in-situ leaching well fields according to the characteristics of the in-situ leaching solution, and can estimate the radon release amount of the entire well field in combination with the local meteorological conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation environment monitoring for in-situ leaching of uranium, and particularly to a radon diffusion device for in-situ leaching of uranium and a method for measuring radon release amount. Background Technique

[0002] The in-situ leaching technology for uranium, also known as the in-situ leaching technology for uranium, consists of two major parts: in-situ leaching and leachate treatment. The former is a cyclic process in which a lixiviant is used through an injection borehole to transfer uranium in the ore from the solid phase to the liquid phase to form a leachate, which is then extracted to the surface through a pumping borehole; the latter is the process of treating the leachate to finally obtain a uranium concentrate product. The leachate itself dissolves radon, and the radon generated by the decay of radium is continuously released, and finally released into the air at the opening of the pumping borehole. Radon is a gaseous radioactive gas that is harmful to the human body and is one of the targets for radiation protection control.

[0003] Measuring the radon release rate of uranium mining and metallurgy facilities sites is an important prerequisite for accurately carrying out environmental impact assessment, effectively strengthening radiation protection supervision, and specifically carrying out radioactive pollution prevention and control. In recent years, the in-situ leaching technology for uranium has developed rapidly. By creating an environment similar to the reverse process of sandstone uranium ore formation, this technology can economically, effectively and greenly exploit complex sandstone-type uranium ore resources; it has greatly reduced the effective public dose caused by radon and its daughters during the uranium mining and metallurgy process. However, there are still problems such as unclear radon release amount and weak monitoring data basis in the monitoring and evaluation technologies supporting the new equipment technology.

[0004] It is difficult to measure the radon concentration and release amount of radon escaping from the pumping borehole into the air. The present invention provides a radon diffusion device for in-situ leaching of uranium and a method for measuring radon release amount. Summary of the Invention

[0005] The purpose of the present invention is to provide a radon diffusion device for in-situ leaching of uranium and a method for measuring radon release amount, which simulate the spatial environment of the pumping borehole in the in-situ leaching process of uranium, collect the radon concentrations at different positions in this environment, and further calculate the radon release amount.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] A radon diffusion device for in-situ leaching of uranium, which is used to simulate the spatial environment of the pumping borehole in the in-situ leaching process of uranium and collect the radon concentrations at different positions in this spatial environment, includes: a radon generator, a diffusion component, a radon detector, a radon absorption component, and a constant temperature sleeve;

[0008] The radon generator is a container with a closed bottom and four sides and an open top, filled with a radon source inside, and is hermetically connected to the diffusion component. A filter membrane that can filter radon daughters and does not absorb radon gas is provided at the connection for filtering radon gas;

[0009] The diffusion component is a hollow tube extending in the vertical direction. The top of the diffusion component is connected to the radon absorption component. The top opening of the radon absorption component is communicated with the external environment. The radon absorption component is used to absorb excess radon gas;

[0010] The radon detector is arranged inside the diffusion component, and the number of the radon detectors is greater than or equal to 3;

[0011] The constant temperature sleeve is sleeved outside the diffusion component, and the hollow part between the diffusion component and the constant temperature sleeve is for circulating and flowing constant temperature liquid.

[0012] The present invention also provides a method for measuring the radon release amount in in-situ leaching uranium mining, including:

[0013] Obtaining the radon concentration values at different positions collected by using the above radon diffusion device, and obtaining the distance between the radon detector and the radon source corresponding to each radon concentration value;

[0014] Performing linear regression on each of the radon concentration values and each of the distances by using the least squares method to obtain the effective radon diffusion coefficient;

[0015] Obtaining the radon concentration at the outlet where the pumping borehole is communicated with the environment according to the effective radon diffusion coefficient;

[0016] Calculating the radon release amount of the pumping borehole according to the radon concentration at the outlet.

[0017] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0018] The present invention provides an in-situ leaching uranium mining radon diffusion device and a method for measuring the radon release amount. By providing a set of in-situ leaching uranium mining radon diffusion devices to simulate the spatial environment of the pumping borehole in the in-situ leaching uranium mining process, collecting the radon concentrations at different positions in this environment, obtaining the effective radon diffusion coefficient of the analog environment according to the radon concentrations at different positions, calculating the radon concentration at the connection opening between the top of the pumping borehole and the environment during actual operation according to the effective radon diffusion coefficient, and calculating the radon release amount according to the radon concentration at the opening. It is not necessary to monitor the air radon concentration frequently. It is possible to directly measure the radon concentration at the connection between the surface of the pumping borehole and the environment for a large number of pumping boreholes with similar temperature and humidity environments in the same or different in-situ leaching well fields according to the characteristics of the in-situ leaching solution, and estimate the radon release amount of the entire well field in combination with the local meteorological conditions. It provides a data basis for the radiation environment analysis and radiation environment impact assessment of the in-situ leaching well field; provides a method and basis for the construction management of the in-situ leaching well field, provides a compliance basis for radiation environment supervision, and provides a direction reference for further reducing the effective public dose of surrounding residents. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 Structural diagram of the radon diffusion device for in-situ leaching uranium provided in Embodiment 1 of the present invention;

[0021] Figure 2 Flowchart of the measurement method for radon release amount provided in Embodiment 2 of the present invention;

[0022] Figure 3 Schematic diagram of the fitting result of radon concentration and diffusion distance provided in Case (I) of the implementation of the present invention;

[0023] Figure 4 Schematic diagram of the fitting result of radon concentration and diffusion distance provided in Case (II) of the implementation of the present invention.

[0024] Symbol description:

[0025] 1 - Radon generator; 2 - Diffusion component; 3 - Radon detector; 4 - Radon absorption component; 5 - Constant temperature sleeve; 6 - Radon source; 7 - Filter membrane. Specific implementation manners

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] In-situ leaching uranium technology, also known as in-situ uranium leaching technology, does not extract uranium ore to the surface for treatment. Instead, groundwater is used to add a leaching solution prepared with leaching agents such as CO2 gas and O2 gas, and is injected into the sandstone-type uranium ore layer under natural burial conditions through injection boreholes, changing the geochemical environment during uranium deposition and mineralization. Oxygen is used to oxidize tetravalent uranium to hexavalent uranium, and bicarbonate is used to complex with hexavalent uranium to dissolve uranium, forming a uranium-containing leaching solution, which is then lifted to the surface through pumping boreholes and transported to the hydrometallurgy workshop, and processed into products through processes such as adsorption, elution, and precipitation. This process consists of two major parts: in-situ leaching and leaching solution treatment. The present invention aims at the radiation environment monitoring requirements for the radon concentration release in the pumping boreholes during the in-situ leaching process.

[0028] In the initial stage of the development of in-situ leaching uranium mines, due to the unclear understanding of the technical characteristics and processes, the calculation of the radon release amount in the in-situ leaching process was estimated based on the complete release of radon in groundwater, seriously exaggerating the radon release trend in the in-situ leaching process, which is obviously inconsistent with the actual situation.

[0029] To scientifically determine the radon release amount of the gaseous source term in in-situ leaching uranium mines, provide accurate source term data for the radiation environmental impact assessment of in-situ leaching mines, thereby reducing the radiation environmental impact estimated by the existing source term determination method to a true and reasonable level, avoiding unreasonable radiation protection measures and costs, reducing social disputes, and promoting the sustainable development of in-situ leaching uranium mines.

[0030] It is difficult to measure the radon concentration and release amount of the radon escaping from the pumping borehole to the air. The in-situ leaching pumping borehole is a semi-closed system, and the total release concentration of radon in the in-situ leaching solution (product solution) can be as high as 200 kBq / m 3 , and the dissolved radon diffuses into the air in the limited space above the liquid level of the pumping borehole and finally enters the atmospheric environment at the pumping borehole opening on the ground. Due to the small space at the pumping borehole opening, the volume of the sample gas available for sampling is usually only a few hundred milliliters. The active sampling equipment's pump suction sampling will change the internal flow field of the pumping borehole, accelerating the radon desorption release or attracting the air outside the borehole into the sampling space, resulting in inaccurate samples; the passive radon detector usually cannot be placed at the sampling position due to its volume, or it blocks the air flow in the pumping borehole and cannot effectively monitor. In addition, there are usually hundreds or thousands of pumping boreholes in an in-situ leaching well field. There are problems with sampling representativeness and monitoring coverage in direct monitoring, so it is difficult to monitor the radon concentration at the outlet.

[0031] Even if the radon concentration at the connection opening between the upper part of the in-situ leaching pumping borehole and the environment is obtained, it is still difficult to determine the radon release amount. Since the radon emission from this facility is free diffusion and the radon-containing gas at the outlet is carried away by the surrounding air flow, there is no organized air flow, so it is difficult to determine the radon release amount.

[0032] The purpose of the present invention is to provide an in-situ leaching uranium radon diffusion device and a method for measuring the radon release amount. By simulating the spatial environment of the pumping borehole in the in-situ leaching uranium process, collecting the radon concentrations at different positions in this environment, and further calculating the radon release amount, it provides a data basis for the radiation environmental analysis and radiation environmental impact assessment of the in-situ leaching well field; provides methods and basis for the construction management of the in-situ leaching well field, provides a basis for radiation environmental supervision, and provides a direction reference for further reducing the effective public dose of the surrounding residents.

[0033] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0034] Example 1

[0035] In practical applications, to calculate the radon concentration and radon release amount at the surface opening of the pumping borehole in the in-situ leaching uranium extraction process, the 222 effective diffusion coefficient of Rn is required. Therefore, to calculate the radon concentration and radon release amount, it is first necessary to obtain the 222 effective diffusion coefficient of Rn. In this embodiment, by simulating the spatial environment of the pumping borehole in the in-situ leaching uranium extraction process and collecting the radon concentrations at different positions in the spatial environment, the 222 effective diffusion coefficient of Rn is further obtained.

[0036] This embodiment provides a radon diffusion device for in-situ leaching uranium extraction, which is used to simulate the spatial environment of the pumping borehole in the in-situ leaching uranium extraction process and collect the radon concentrations at different positions in the spatial environment. Please refer to Figure 1 ., the radon diffusion device includes: a radon generator 1, a diffusion component 2, a radon detector 3, a radon absorption component 4, and a constant temperature sleeve 5;

[0037] The radon generator 1 is a container with a closed bottom and four sides and an open top, containing a radon source 6 inside, and is sealed and connected to the diffusion component 2. Specifically, it can be sealed and connected to the diffusion component 2 by means of sleeves, flanges, bolts, etc. A filter membrane 7 that can filter radon daughters and does not absorb radon gas is provided at the connection to release radon gas and prevent 222 Rn and 220 Rn daughters from diffusing into the diffuser;

[0038] The radon generator 1 is located at the bottom of the radon diffusion device for in-situ leaching uranium extraction. The radon source 6 can use a radium source or a uranium ore source as the radon source 6. It is recommended to use a uranium ore source. The concentration of the radon source 6 is controllable. During use, a radon concentration of at least 400 Bq / m 3 or more is selected as the effective working range.

[0039] The diffusion component 2 is a hollow tube extending in the vertical direction. The top of the diffusion component 2 is connected to the radon absorption component 4. The top opening of the radon absorption component 4 is connected to the external environment. The radon absorption component 4 is used to absorb excess radon gas; the radon absorption component 4 can use activated carbon.

[0040] Optionally, the diffusion component 2 is composed of a plurality of diffusion tubes connected in sequence in the vertical direction, and a layer of the filter membrane 7 is provided at the connection part of two adjacent diffusion tubes.

[0041] The radon detector 3 is arranged inside the diffusion component 2, and the number of the radon detectors 3 is greater than or equal to 3; among them, the position of the radon detector 3 closest to the radon source 6 should be more than 500 mm away from the radon source 6 and more than 400 mm away from the activated carbon at the top. The other radon detectors 3 can be arranged at equal distances or randomly. When calculating the effective diffusion coefficient of radon, the distances between the radon detector 3 and the radon source 6 and the radon outlet need to be recorded. The radon detector 3 should be passive222 Rn detector, sampling detection through active devices is not allowed. 222 Rn concentration. Passive 222 The number of Rn detectors should be controlled so that the detector volume does not exceed 10% of the total volume of the diffusion component 2.

[0042] The constant temperature sleeve 5 is sleeved outside the diffusion component 2. The hollow part between the diffusion component 2 and the constant temperature sleeve 5 is filled with constant temperature liquid, and the constant temperature liquid circulates through a constant temperature pump. In this embodiment, the temperature of the liquid extraction drilling hole of the experimental mold is controlled and maintained within ±0.5 °C of the target temperature, and the target temperature range is 5 °C - 45 °C. The humidity RH is controlled between 40% - 90%.

[0043] Using the above device for simulation measurement 222 The effective diffusion coefficient of Rn free diffusion in the vertical direction. After the device is connected, check the airtightness, test the effectiveness of the control system, and turn on the constant temperature circulating water to adjust the temperature of the diffusion component 2 to the experimental state. To control the experimental background level, it is necessary to purge the diffusion component 2 with compressed nitrogen. After purging, seal the system, install an activated carbon package, connect the radon source 6, and install 222 Rn detector and start timing detection. 222 The cumulative detection time of Rn should be greater than 2 weeks.

[0044] Embodiment 2

[0045] This embodiment provides a method for measuring the radon release amount in in-situ leaching uranium mining. Please refer to Figure 2 , including:

[0046] S1. Obtain the radon concentration values at different positions collected by the in-situ leaching uranium mining radon diffusion device, and obtain the distances between the radon detectors 3 and the radon source 6 corresponding to the respective radon concentration values;

[0047] Among them, the in-situ leaching uranium mining diffusion device is the diffusion device described in Embodiment 1.

[0048] S2. Perform linear regression on each of the radon concentration values and each of the distances using the least squares method to obtain the effective radon diffusion coefficient;

[0049] The regression form of the trend line is:

[0050] y = Ae Bx (1)

[0051] Among them, A and B are linear regression constants, and x is the distance between the radon source 6 and the radon detector 3;

[0052] 222 The effective radon diffusion coefficient D e is:

[0053] D e = λ / B2 (2)

[0054] Among them, D e is the effective diffusion coefficient of Rn measured experimentally 222 ; λ is the 222 decay constant of Rn; B is the constant obtained by regression calculation.

[0055] S3. Obtain the radon concentration at the outlet where the pumping borehole is connected to the environment according to the effective radon diffusion coefficient;

[0056] After obtaining 222 the effective diffusion coefficient of Rn, the effective diffusion coefficient can be used during the actual operation of the pumping borehole to calculate the radon concentration at the surface opening of the actual pumping borehole.

[0057] 222 The distribution of the radon concentration during the free diffusion of Rn in the vertical direction conforms to the emanation distribution law of a layered homogeneous non-radioactive medium, that is:

[0058]

[0059] Among them, C is the radon concentration at the outlet where the pumping borehole is connected to the environment, with the unit Bq / m 3 ; C0 is the radon concentration in the air at the leachate liquid level in the pumping borehole, and this concentration is the product of the radon concentration in the leachate water and the Ostwald coefficient of the groundwater environment temperature. Bq / m 3 ; e is the base of the natural logarithm; λ is the 222 decay constant of Rn, s -1 ; D e is the effective diffusion coefficient of Rn measured experimentally 222 , m 2 s -1 ; X is the distance from the leachate liquid level of in-situ leaching to the outlet where the pumping borehole is connected to the environment, m.

[0060] S4. Calculate the radon release amount of the pumping borehole according to the radon concentration at the outlet.

[0061] After knowing the radon concentration at the outlet where the pumping borehole is connected to the environment described in S3, the free diffusion release amount of radon from the pumping borehole can be calculated using the location of the pumping borehole and the daily and hourly meteorological conditions.

[0062] The investigation of the radon release source term intensity of the pumping borehole can be carried out through the radon concentration monitoring at the opening, the pressure difference inside and outside the pumping borehole, and the effective opening area. According to Bernoulli's equation, the outlet volume flow rate is mainly determined by the pressure difference inside and outside, including the thermal pressure difference and the wind speed pressure difference. The calculation formula is as follows:

[0063]

[0064] Q is the annual radon release from the borehole, Bq / a; C is the average radon concentration in the pumping borehole, Bq / m 3 ; A is the effective opening area of the pumping borehole, m 2 ;P i is the frequency of wind speed segment i of effective wind speed on the surface; g is the acceleration of gravity, 9.8m / s -2 ρ n , w is the density of the air in the pumping borehole and the surrounding air, kg / m 3 ;v i The location of the facility P i Wind speed segment: wind speed, m / s.

[0065] The method of this embodiment does not require monitoring of air radon concentration. A large number of pumping boreholes with similar temperature and humidity environments in the same or different leaching well fields can be used to directly measure the radon concentration at the connection point between the surface of the pumping borehole and the environment based on the characteristics of the leaching fluid. The radon release amount of the entire well field can be estimated in combination with local meteorological conditions.

[0066] In order to more clearly illustrate the solution of the present invention, two specific implementation cases are used for illustration below.

[0067] Implementation Case (I)

[0068] The diffusion component 2 is manufactured to be 2.5m high and 0.3m in inner diameter. The bottom is connected to a self-made radon chamber made of uranium ore as a radon source 6. A composite glass fiber filter membrane is installed at the connection between the radon source 6 and the diffusion component 2 to filter the daughter body. After the radon gas passes through the filtration, it can diffuse freely in the vertical direction.

[0069] Radon source 6 is a uranium ore type self-made radon source 6, which controls the stable radon concentration to 800Bq / m 3 .

[0070] Install a fixed distance passive radon detector 3. In this case, a solid track detector KF606B is used to measure the radon concentration. Passive radon detectors 3 are placed at the corresponding positions of the diffusion tube at 0.5m, 1m, 1.5m, 2m, and 2.5m to avoid disturbing the airflow.

[0071] Terminal radon absorption component 4: An activated carbon bag is installed on the top to absorb excess radon to prevent its release into the environment. The activated carbon used is made from fruit shells through high-temperature carbonization and activation. It has the appearance of black block activated carbon of varying sizes, and the usage is 500g.

[0072] Constant temperature sleeve 5: It adopts a hollow sleeve structure and is located outside the diffusion component 2. The sleeve gap uses a constant temperature pump to circulate constant temperature liquid to control the temperature of the diffusion component 2. The experimental model controls the temperature of the liquid extraction drilling hole and controls the temperature of the diffusion component 2 system at 16±0.5℃. The relative humidity of the device simulates the liquid extraction drilling environment. The relative humidity RH measured during the experiment is 67%-86%.

[0073] After connecting the device, check the airtightness and test the effectiveness of the constant temperature circulating water control system. Turn on the constant temperature circulating water and adjust the temperature of the diffusion component 2 to the experimental state, with the temperature being 16 ± 0.5 °C. Before the experiment, purge the system with compressed air that has been stored for more than 10 years. After purging, seal the pipeline, install the activated carbon package, connect the radon source 6, install the KF606B radon detector 3 and start timing. At the same time, arrange 3 blank detectors around the diffusion tube, turn off the detector switches as blank comparison samples, and the experiment lasts for 15 days. The equilibrium concentration of radon in the radon chamber is 800 Bq / m 3 The activated carbon package is installed at the top to absorb the excess radon inside and block the interference of external radon gas.

[0074] After 362 hours from the start of the experiment, take out the KF606B detector to measure the radon concentration. The results are shown in the following table.

[0075] Table 1 Radon constant temperature vertical diffusion data results in one-dimensional vertical space

[0076]

[0077] The fitting result using the least squares method is shown in Figure 3 Based on this, the effective diffusion coefficient De of radon in the vertical space at 16 °C in this experiment can be calculated as 0.0578 cm 2 s -1 .

[0078] The radon concentration in the leachate of the pumping hole 23# in the 6th mining area of the stope where the research target is located is 2.04×10 5 Bq / m 3 , and the equilibrium Oswald coefficient of radon in the gas-liquid two-phase at 16 °C is 0.3. Then, the radon concentration in the air at the leachate liquid surface is calculated as 61 kBq / m 3 .

[0079] The pumping hole 23# in the 6th mining area of this stope is 8.65 m away from the ground surface. The part above the ground surface is 0.23 m away from the opening, and the liquid surface is 8.88 m away from the opening of the pumping borehole. It can be calculated through Equation (3) that the radon concentration at the outlet of the pumping borehole is 290.3 Bq / m 3 . This result has a difference in the average radon concentration of 15.4 Bq / m 3 from the on-site measured result of 304.2 Bq / m 3 , with a deviation of 4.57%.

[0080] Using the meteorological data of this area in 2015, the annual radon release amount of this pumping borehole is calculated through Equation (4) as 1.53×10 8 Bq / a.

[0081] Implementation case (two)

[0082] (I) The diffusion component 2 is manufactured to be 2.5m high and 0.3m in inner diameter. The bottom is connected to a radium source system standard radon source 6 as a radon source 6. A high-density glass fiber filter membrane is installed at the connection between the radon source 6 and the diffusion component 2 to filter the daughter body. After the radon gas passes through the filtration, it can freely diffuse in the vertical direction.

[0083] Radon source 6 is RN150 radon source 6, which controls the stable radon concentration to 1000Bq / m 3 .

[0084] A fixed distance passive radon measuring device is installed. In this case, the American e-perm electret radon detector 3 is used. A Loo type diffusion cavity sensitive electret sheet is used. Radon detectors 3 are placed at 0.5m, 1m, 1.5m, 2m, and 2.5m at the corresponding positions of the diffusion component 2 to avoid disturbing the airflow.

[0085] Terminal radon absorption component 4: An activated carbon bag is installed on the top to absorb excess radon to prevent its release into the environment. The activated carbon used is made from fruit shells through high-temperature carbonization and activation. It has the appearance of black block activated carbon of varying sizes, and the usage is 500g.

[0086] Constant temperature sleeve 5: It adopts a hollow sleeve structure and is located outside the diffusion component 2. The sleeve gap uses a constant temperature pump to circulate constant temperature liquid to control the temperature of the diffusion component 2. The experimental model controls the temperature of the liquid extraction drilling hole and controls the temperature of the diffusion component 2 system at 18±0.5℃. The relative humidity of the device simulates the liquid extraction drilling environment. The relative humidity RH measured during the experiment is 74%-82%.

[0087] After connecting the device, check the air tightness, test the effectiveness of the constant temperature circulating water control system, turn on the constant temperature circulating water to adjust the temperature of the diffusion component 2 to the experimental state, the temperature is 18±0.5℃. Use compressed nitrogen to purge the system before the experiment. After the purge is completed, close the pipeline and install the activated carbon bag, connect the radon source 6, install the electret detector and start the timing, and arrange 2 blank detectors in the surrounding environment of the diffusion tube. Turn off the detector switch as a blank comparison sample. The experiment lasts for 72 hours. The equilibrium concentration of the radon chamber is 1000Bq / m 3 , activated carbon is packed into the top to absorb excess radon gas inside and block external radon gas interference.

[0088] 72 hours after the experiment started, the electret detector was taken out to measure the radon concentration. The results are shown in the following table.

[0089] Table 2 One-dimensional vertical space radon constant temperature vertical diffusion

[0090]

[0091] The least squares fitting results are shown in Figure 4 Based on this, the effective diffusion coefficient De of radon in this experiment at 18°C in vertical space is calculated to be 0.0589 cm2 s -1 。

[0092] Taking the radon concentration in the leaching solution of the 12# liquid extraction hole in the 4th mining area of the stope where the research target is located as 1.87×10 5 Bq / m 3 , and the equilibrium Oswald coefficient of radon in the gas-liquid two-phase at 18°C is 0.31, then the radon concentration in the air at the liquid level of the in-situ leaching solution is calculated to be 58 kBq / m 3 。

[0093] The 12# liquid extraction hole in the 4th mining area of this stope is 8.81 m away from the ground surface. The part above the ground surface is 0.32 m away from the opening, and the liquid level is 9.13 m away from the opening of the liquid extraction borehole. It can be calculated through Equation (3) that the radon concentration at the outlet of the liquid extraction borehole is 240.6 Bq / m 3 。This result has a difference in the average radon concentration of 8.9 Bq / m 3 from the on-site measured result of 249.5 Bq / m 3 , and the deviation is 3.56%.

[0094] Using the meteorological data of this area in 2015, the annual release amount of radon from this liquid extraction borehole is calculated through Equation (4) to be 1.27×10 8 Bq / a。

[0095] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0096] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for measuring the radon release amount in in-situ leaching of uranium, characterized in that, It is used to simulate the spatial environment of the pumping borehole in the in-situ leaching uranium extraction process and collect the radon concentrations at different positions in the said spatial environment, including: a radon generator, a diffusion component, a radon detector, a radon absorption component, and a constant temperature sleeve; The said radon generator is a container with a closed bottom and perimeter and an open top, filled with a radon source inside, hermetically connected to the diffusion component, and a filter membrane that can filter radon daughters and does not absorb radon gas is provided at the connection for filtering radon gas; The said diffusion component is a hollow tube extending in the vertical direction. The top of the diffusion component is connected to the radon absorption component. The top opening of the radon absorption component is in communication with the external environment. The radon absorption component is used to absorb excess radon gas; The said radon detector is arranged inside the diffusion component, and the number of the radon detectors is greater than or equal to 3; The said constant temperature sleeve is sleeved outside the diffusion component; the hollow part between the diffusion component and the constant temperature sleeve is for circulating and flowing constant temperature liquid; The calculation method of the radon release rate from the pumping borehole is as follows: linear regression is performed on the radon concentration values detected by each radon detector and the distances between each radon detector and the radon source using the least squares method to obtain the effective radon diffusion coefficient; based on the effective radon diffusion coefficient, the radon concentration at the outlet where the pumping borehole is connected to the environment is obtained; based on the radon concentration at the outlet, the radon release rate from the pumping borehole is calculated using the formula to calculate the radon release rate from the pumping borehole; where Q is the annual radon release rate of the borehole; C is the average radon concentration of the pumping borehole; A is the effective opening area of the pumping borehole; P i is the frequency of the effective wind speed i wind speed segment on the ground surface; g is the acceleration due to gravity; ρ n , ρ w are the air densities inside the pumping borehole and in the environment respectively; v i is the wind speed of the P i wind speed segment at the location of the facility.

2. The method according to claim 1, wherein The radon detector closest to the radon source is at a distance greater than 500 mm from the radon source and at a distance greater than 400 mm from the radon absorption component.

3. The method according to claim 1, wherein The said radon detector is a passive radon detector, and the total volume of the passive radon detector is less than or equal to 10% of the total volume of the diffusion component.

4. The method according to claim 1, wherein The said diffusion component is formed by sequentially connecting a number of diffusion tubes in the vertical direction, and a layer of the filter membrane is provided at the connection part between two adjacent diffusion tubes.

5. The method according to claim 1, wherein The ratio of the length to the width of the said diffusion component is greater than 5:

1.

6. The method according to claim 1, wherein When collecting radon concentration using a radon diffusion device, the selected radon source concentration is greater than or equal to 400 Bq / m 3 .

7. The method according to claim 1, wherein Performing linear regression on each of the said radon concentration values and each of the said distances using the least squares method to obtain the effective radon diffusion coefficient, specifically including: The regression form of the trend line is: y = Ae Bx where A and B are linear regression constants, and x is the distance between the radon source and the radon detector; 222 The effective diffusion coefficient D of Rn e is as follows: D e = λ / B 2 Among them, D e is the effective diffusion coefficient of Rn measured experimentally 222 ; λ is the 222 decay constant of Rn; B is the constant obtained by regression calculation.

8. The method according to claim 1, wherein Obtaining the radon concentration at the outlet where the pumping borehole is in communication with the environment according to the said effective radon diffusion coefficient, specifically including: According to the formula obtain the radon concentration at the outlet where the liquid extraction borehole is connected to the environment: Among them, C is the radon concentration at the outlet where the liquid extraction borehole is connected to the environment; C0 is the radon concentration in the air at the liquid level in the liquid extraction borehole, and the air radon concentration is the product of the radon concentration in the leaching solution water and the Ostwald coefficient of the groundwater environment temperature; e is the base of the natural logarithm; λ is 222 the decay constant of Rn; D e is 222 the effective diffusion coefficient of Rn; X is the distance from the liquid level of the in-situ leaching solution to the outlet where the liquid extraction borehole is connected to the environment.

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