Method for separating thorium and uranium
By adding phosphate or pyrophosphate to the uranium ore wastewater as a separator to adjust the pH value and constant temperature reaction, the complex and cost-effective separation of thorium and uranium in the existing technology is solved, and efficient separation and recycling of thorium and uranium is achieved, reducing environmental pollution.
Patent Information
- Application Number
- CN202411687006.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-02-25
AI Technical Summary
The prior art has problems such as complex synthesis of adsorbents, high cost, large secondary waste liquid of extraction method, unfavorable capacity reduction treatment, membrane separation method requires special equipment, and membrane is prone to clogging and high cost, making it difficult to effectively solve the problems of thorium and uranium pollution in uranium ore wastewater.
By adding phosphate or pyrophosphate as a separator to the wastewater containing thorium and uranium, adjust the pH to 1-2, place it under constant temperature, and react, and then separate the suspension after cooling to achieve solid-liquid separation of thorium and uranium.
It has achieved the effect of separating more than 95% of the thorium precipitation and separation of more than 85% of the uranium in the wastewater. It is simple to operate, low cost and has wide application value.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for separating thorium and uranium. Background Art
[0002] As a clean energy with near-zero emissions, nuclear energy can make a huge contribution to the global climate. At present, uranium fission is the main source of nuclear energy, but the limited natural uranium resources will inevitably become a bottleneck problem restricting the development of nuclear energy in the future. Thorium is considered to be the fuel for the next generation of nuclear reactors. Its content is about 4 times that of uranium, and it produces non-persistent radioactive pollution and has less impact on the environment. Therefore, thorium and uranium have extremely high application value as strategic resources.
[0003] Uranium mines are generally polymetallic deposits, with thorium and uranium co-existing and enriched. However, due to the defects in uranium mining and extraction technology and the long-term oxidation and weathering of exposed tailings, a large amount of acidic smelting wastewater containing thorium and uranium is produced during uranium mining, which in turn causes serious pollution to the soil, groundwater and surface water around mining and smelting. Therefore, it is urgent to develop a technology that can efficiently separate and recover thorium and uranium in wastewater to ensure the active and orderly development of nuclear energy under the premise of ecological and environmental safety.
[0004] At present, the separation of thorium and uranium mainly focuses on technologies such as adsorption, extraction and membrane separation. Among them, the adsorption method faces the problem of complex adsorbent synthesis and post-processing process and high cost; the extraction method faces the problem of large amount of secondary waste liquid, which is not conducive to volume reduction treatment; the membrane separation method requires the use of special equipment, the membrane is easy to clog, and the cost is high. Therefore, it is very necessary to develop a new solution for the separation of thorium and uranium. Summary of the invention
[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a method for separating thorium and uranium, which can efficiently separate thorium and uranium in wastewater, thereby realizing the recovery of thorium and uranium resources and solving the problem of uranium mine wastewater pollution.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is:
[0007] The present invention provides a method for separating thorium and uranium, the method comprising the following steps:
[0008] S1. Adding a separation agent to the wastewater containing thorium and uranium, wherein the separation agent is phosphate or pyrophosphoric acid, mixing well and adjusting the pH to obtain a mixture;
[0009] S2. The mixture in step S1 is placed under a constant temperature condition for reaction. After the reaction is completed, the mixture is cooled to room temperature, and the resulting suspension is separated to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid, thereby achieving separation of thorium and uranium.
[0010] Preferably, the pH in S1 is adjusted to 1-2. More preferably, the pH in S1 is adjusted to 1.
[0011] The present invention realizes the separation of thorium and uranium in wastewater by utilizing the principle that phosphate or pyrophosphoric acid reacts with thorium under hydrothermal or normal temperature conditions to form a precipitate, but does not react with uranium. When pH=1, phosphate and thorium under hydrothermal conditions or pyrophosphoric acid and thorium under normal temperature conditions can form thorium pyrophosphate or thorium phosphate precipitate with thorium, but do not react with uranium, so that more than 95% of the thorium in the solution forms a precipitate and is separated, while more than 85% of the uranium remains in the solution, realizing the solid-liquid separation of thorium and uranium. The method for separating thorium and uranium provided by the present invention is simple to operate, low in cost, and has a wide range of application value.
[0012] Preferably, the phosphate includes sodium dihydrogen phosphate and potassium dihydrogen phosphate.
[0013] Preferably, when phosphate is used as a separating agent, the molar ratio of thorium, uranium and phosphorus in the mixture of S1 is 1:1:(1-18).
[0014] Preferably, when pyrophosphoric acid is used as a separating agent, the molar ratio of thorium, uranium and phosphorus in the mixture of S1 is 1:1:(1-18).
[0015] Preferably, when phosphate is used as a separating agent, the temperature of the constant temperature condition in S2 is 180-220°C.
[0016] Preferably, when pyrophosphoric acid is used as the separating agent, the temperature of the constant temperature condition in S2 is 20-30°C.
[0017] Preferably, in S2, the isothermal reaction time is 2-3 days.
[0018] Preferably, the regulator used to adjust the pH in S1 is a nitric acid solution and a sodium hydroxide solution.
[0019] Preferably, in the wastewater containing thorium and uranium described in S1, the concentration of thorium or uranium is 5-200 mg / L.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The invention discloses a method for separating thorium and uranium. A separation agent (pyrophosphate or phosphate) is added to wastewater containing thorium and uranium, and the pH is adjusted after mixing. After the reaction, the obtained suspension is separated to obtain a thorium-rich and uranium-depleted solid and a uranium-rich and thorium-depleted liquid, thereby achieving the separation of thorium and uranium. The invention allows pyrophosphate to form thorium pyrophosphate or thorium phosphate precipitation with thorium at room temperature or phosphate under hydrothermal conditions without reacting with uranium, so that more than 95% of the thorium in the wastewater forms precipitation and 85% of the uranium remains in the solution, thereby achieving the solid-liquid separation of thorium and uranium. The method provided by the invention is simple to operate, low in cost, and has a wide range of application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 To study the effect of different pH values on the removal rate and separation effect of thorium and uranium in wastewater when sodium dihydrogen phosphate is used as the separation agent.
[0023] Figure 2 To study the effect of different temperatures on the removal rate and separation effect of thorium and uranium in wastewater when sodium dihydrogen phosphate is used as the separation agent.
[0024] Figure 3 To study the effect of different dosages of sodium dihydrogen phosphate on the removal rate and separation effect of thorium and uranium in wastewater when sodium dihydrogen phosphate is used as a separation agent.
[0025] Figure 4 To study the effect of different pH values on the removal rate and separation effect of thorium and uranium in wastewater when pyrophosphoric acid is used as a separation agent.
[0026] Figure 5 This paper studies the effect of different pyrophosphoric acid dosage on the removal rate and separation effect of thorium and uranium in wastewater when pyrophosphoric acid is used as a separation agent. DETAILED DESCRIPTION
[0027] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0028] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.
[0029] In the following examples, the preparation method of the mixed wastewater of thorium and uranium is as follows: 30 mL of a 1000 mg / L thorium standard solution and 30 mL of a 1000 mg / L uranium standard solution are pipetted into a 100 mL volumetric flask, and the volume is fixed with deionized water to obtain a mixed wastewater of thorium and uranium with a thorium and uranium concentration of 300 mg / L.
[0030] Example 1: A method for separating thorium and uranium
[0031] (1) Take 0.5 mL of 300 mg / L thorium and uranium mixed wastewater, add sodium dihydrogen phosphate to it, mix well, make up to 30 mL with deionized water, and adjust the pH value of the solution to 1, 2, 3, and 4 with sodium hydroxide and nitric acid solutions, respectively, so that the molar ratio of thorium, uranium, and phosphorus in the obtained mixture is 1:1:6.
[0032] (2) The mixture in step (1) was transferred into a polytetrafluoroethylene reactor, and then placed in an electric constant temperature drying oven for reaction at 200° C. for 3 days.
[0033] (3) After the reaction is completed, the mixture is cooled to room temperature and the suspension is separated by centrifugation to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid.
[0034] Example 2: A method for separating thorium and uranium
[0035] (1) Take 0.5 mL of mixed wastewater containing 300 mg / L thorium and uranium, add sodium dihydrogen phosphate, mix well, make up to 30 mL with deionized water, and adjust the pH value of the solution to 1 with sodium hydroxide and nitric acid solution, so that the molar ratio of thorium, uranium and phosphorus in the obtained mixture is 1:1:6.
[0036] (2) The mixture in step (1) was transferred into a polytetrafluoroethylene reactor, and then placed in an electric constant temperature drying oven for reaction at 25° C., 75° C., 120° C., and 200° C. for 3 days.
[0037] (3) After the reaction is completed, the mixture is cooled to room temperature and the suspension is separated by centrifugation to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid.
[0038] Example 3: A method for separating thorium and uranium
[0039] (1) 0.5 mL of mixed wastewater containing 300 mg / L thorium and uranium was taken, sodium dihydrogen phosphate was added thereto, and after mixing evenly, the volume was made up to 30 mL with deionized water, and the pH value of the solution was adjusted to 1 with sodium hydroxide and nitric acid solutions, so that the molar ratios of thorium, uranium and phosphorus in the obtained mixture were 1:1:1, 1:1:6, 1:1:12 and 1:1:18, respectively.
[0040] (2) The mixture in step (1) was transferred into a polytetrafluoroethylene reactor, and then placed in an electric constant temperature drying oven for reaction at 200° C. for 3 days.
[0041] (3) After the reaction is completed, the mixture is cooled to room temperature and the suspension is separated by centrifugation to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid.
[0042] Example 4: A method for separating thorium and uranium
[0043] (1) Take 0.5 mL of 300 mg / L thorium and uranium mixed wastewater, add pyrophosphoric acid thereto, mix well, make up to 30 mL with deionized water, and adjust the pH value of the solution to 1, 2, 3, and 4 with sodium hydroxide and nitric acid solutions, respectively, so that the molar ratio of thorium, uranium, and phosphorus in the obtained mixture is 1:1:6.
[0044] (2) The mixture in step (1) was transferred into a polytetrafluoroethylene reactor, and then placed in an electric constant temperature drying oven for reaction at 200° C. for 3 days.
[0045] (3) After the reaction is completed, the mixture is cooled to room temperature and the suspension is separated by centrifugation to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid.
[0046] Example 5: A method for separating thorium and uranium
[0047] (1) Take 0.5 mL of 300 mg / L thorium and uranium mixed wastewater, add pyrophosphoric acid thereto, mix well, make up to 30 mL with deionized water, and adjust the pH value of the solution to 1 with sodium hydroxide and nitric acid solutions, so that the molar ratios of thorium, uranium and phosphorus in the obtained mixture are 1:1:1, 1:1:6, 1:1:12 and 1:1:18, respectively.
[0048] (2) The mixture in step (1) was transferred into a polytetrafluoroethylene reactor, and then placed in an electric constant temperature drying oven for reaction at 200° C. for 3 days.
[0049] (3) After the reaction is completed, the mixture is cooled to room temperature and the suspension is separated by centrifugation to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid.
[0050] Experimental Example 1: Determination of Thorium Removal Rate
[0051] The thorium removal rates in Examples 1-5 were measured:
[0052] 5 mL of the suspension obtained in step (3) of Examples 1-5 were taken respectively, filtered with a 0.22 μm microporous filter membrane, and the filtrate obtained was analyzed for thorium concentration in the solution using an inductively coupled plasma emission spectrometer, and the thorium removal rate was further calculated. Figure 1 As shown, using sodium dihydrogen phosphate as the separation agent, at 200°C, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the pH values are 1, 2, 3, and 4, respectively. The thorium removal rates are 97.3%, 97.8%, 99.8%, and 99.9%, respectively. Figure 2As shown in the figure, using sodium dihydrogen phosphate as the separation agent, the pH value is 1, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the temperature is 25℃, 75℃, 120℃, and 200℃, the thorium removal rate is 1.8%, 4.4%, 4.6%, and 97.3%, respectively. Figure 3 As shown, using sodium dihydrogen phosphate as the separation agent, at 200°C, pH value of 1, and the molar ratios of thorium, uranium, and phosphorus of 1:1:1, 1:1:6, 1:1:12, and 1:1:18, the thorium removal rates are 94.6%, 97.3%, 97.4%, and 97.4%, respectively. Figure 4 As shown in the figure, using pyrophosphate as the separation agent, at 25°C, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the pH values are 1, 2, 3, and 4, respectively. The thorium removal rates are 95.6%, 96.6%, 97.4%, and 98.4%, respectively. Figure 5 As shown, when pyrophosphoric acid is used as the separation agent, at 25°C, pH value is 1, and the molar ratios of thorium, uranium and phosphorus are 1:1:1, 1:1:6, 1:1:12 and 1:1:18, the thorium removal rates are 56.8%, 95.6%, 95.8% and 96.1%, respectively.
[0053] Experimental Example 2: Uranium Removal Rate
[0054] The uranium removal rates in Examples 1-5 were measured:
[0055] Take 5 mL of the suspension obtained in step (3) of Examples 1-5 respectively, filter with a 0.22 μm microporous filter membrane, analyze the uranium concentration in the filtrate with an inductively coupled plasma emission spectrometer, and further calculate the uranium removal rate. Figure 1 As shown, using sodium dihydrogen phosphate as the separation agent, at 200°C, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the pH values are 1, 2, 3, and 4, respectively. The uranium removal rates are 6.6%, 12.1%, 86.9%, and 97.4%, respectively. Figure 2 As shown in the figure, using sodium dihydrogen phosphate as the separation agent, the pH value is 1, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the temperature is 25℃, 75℃, 120℃, and 200℃, the uranium removal rate is 0.8%, 2.7%, 4.4%, and 6.6%, respectively. Figure 3 As shown, using sodium dihydrogen phosphate as the separation agent, at 200°C, pH value of 1, and the molar ratios of thorium, uranium, and phosphorus of 1:1:1, 1:1:6, 1:1:12, and 1:1:18, the uranium removal rates are 6.6%, 6.8%, 7.0%, and 7.1%, respectively. Figure 4As shown, using pyrophosphoric acid as a separation agent, at 25°C, the molar ratio of thorium, uranium and phosphorus is 1:1:6, and the pH values are 1, 2, 3, and 4, respectively. The uranium removal rates are 13.3%, 37.1%, 47.2%, and 47.9%, respectively. Figure 5 As shown, when pyrophosphoric acid is used as the separation agent, at 25°C, pH value is 1, and the molar ratios of thorium, uranium and phosphorus are 1:1:1, 1:1:6, 1:1:12 and 1:1:18, the uranium removal rates are 9.1%, 13.3%, 16.3% and 17.2%, respectively.
[0056] It can be seen from the above-mentioned Examples 1-5 and Experimental Examples 1-2 that when the molar ratio of thorium, uranium and phosphorus in the mixture is 1:1:6 and the pH value is 1, if sodium dihydrogen phosphate is used as a separating agent, the thorium removal rate can reach 97.3% at 200°C, but the uranium removal rate is only 6.6%. If pyrophosphoric acid is used as a separating agent, at 25°C, the thorium removal rate reaches 95.6%, while the uranium removal rate is 13.3%. Both can make more than 95% of the thorium form thorium pyrophosphate precipitation and be separated, while more than 85% of the uranium remains in the solution, thereby achieving solid-liquid separation of thorium and uranium.
[0057] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.
Claims
1. A method for separating thorium and uranium, characterized in that: The following steps are involved: S1. Adding a separation agent to the wastewater containing thorium and uranium, wherein the separation agent is phosphate or pyrophosphoric acid, mixing well and adjusting the pH to obtain a mixture; S2. The mixture in step S1 is placed under a constant temperature condition for reaction. After the reaction is completed, the mixture is cooled to room temperature, and the resulting suspension is separated to obtain a thorium-rich and depleted uranium solid and a uranium-rich and thorium-depleted liquid, thereby achieving separation of thorium and uranium.
2. A method for separating thorium and uranium according to claim 1, characterized in that: The phosphate includes sodium dihydrogen phosphate and potassium dihydrogen phosphate.
3. A method for separating thorium and uranium according to claim 1, characterized in that: Adjust the pH in S1 to 1-2.
4. A method for separating thorium and uranium according to claim 1, characterized in that: When phosphate is used as a separating agent, the molar ratio of thorium, uranium and phosphorus in the S1 mixture is 1:1:(1-18).
5. A method for separating thorium and uranium according to claim 1, characterized in that: When pyrophosphate is used as a separating agent, the molar ratio of thorium, uranium and phosphorus in the S1 mixture is 1:1:(1-18).
6. A method for separating thorium and uranium according to claim 1, characterized in that: When phosphate is used as a separating agent, the temperature of the constant temperature condition in S2 is 180-220°C.
7. A method for separating thorium and uranium according to claim 1, characterized in that: When pyrophosphoric acid is used as the separating agent, the temperature of the constant temperature condition in S2 is 20-30°C.
8. A method for separating thorium and uranium according to claim 1, characterized in that: In S2, the isothermal reaction time is 2-3 days.
9. A method for separating thorium and uranium according to claim 1, characterized in that: The regulators used to adjust the pH in S1 are nitric acid solution and sodium hydroxide solution.
10. A method for separating thorium and uranium according to claim 1, characterized in that: In the wastewater containing thorium and uranium described in S1, the concentration of thorium or uranium is 5-200 mg / L.