Method for extracting uranium from low concentration uranium solution by floating extraction

Abstract

This invention discloses a method for uranium extraction from low-concentration uranium liquid using flotation extraction. The method uses an extractant emulsion saponified with alkali as the flotation reagent, which is added to the low-concentration uranium liquid. The pH of the solution is adjusted to 4.0-6.5, and the mixture is thoroughly mixed. An organic receiving phase is spread on the surface of the solution, and air bubbles are introduced to allow the solution to float to the surface. A uranium-loaded organic phase is obtained by separation. The obtained uranium-loaded organic phase can be directly back-extracted, or this uranium-loaded organic phase can be repeatedly used as the organic receiving phase to process the low-concentration uranium liquid multiple times, with uranium continuously enriching into the organic phase to obtain a uranium-rich organic phase. Finally, the uranium-rich organic phase is back-extracted to obtain a high-concentration clean uranium liquid. This invention has the advantages of simple operation, low reagent consumption, and high resource recovery rate, making it suitable for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of rare metal extraction metallurgy, specifically relating to a method for enriching and extracting uranium from a low-concentration uranium solution. Background Technology

[0002] Uranium is the heaviest naturally occurring metal, silvery-white in color, and characterized by its high hardness, density, malleability, and radioactivity. Uranium atoms can undergo fission, releasing large amounts of energy, making it an indispensable fuel for nuclear power generation. In addition, uranium is widely used in military, environmental, and medical fields.

[0003] Mining and industrial production processes also generate large quantities of low-concentration uranium-containing solutions. Direct discharge of these solutions causes severe environmental pollution and wastes the uranium resources within them. The enrichment and purification of uranium in solutions often employs traditional solvent extraction-back-extraction or adsorption methods. Solvent extraction, when applied to low-concentration uranium solutions, requires a high organic-to-water ratio, leading to significant loss of organic reagents and poor economic efficiency; furthermore, the enrichment ratio of uranium in the organic phase is low, and subsequent enrichment processes are lengthy. Adsorption methods are simple to operate, but ion exchange resins are prone to poisoning and deactivation, have short lifespans, and require stringent pretreatment before adsorption; moreover, the resins themselves have high production costs.

[0004] Therefore, there is an urgent need to develop a new method for the efficient and low-cost enrichment and extraction of uranium from low-concentration uranium solutions. Summary of the Invention

[0005] This invention provides a method for uranium extraction by flotation extraction of low-concentration uranium solution, which can quickly and efficiently remove uranium from low-concentration uranium solution and extract it into high-concentration clean uranium solution with a high uranium recovery rate.

[0006] This invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid. The method involves adding a flotation reagent to a low-concentration uranium liquid, adjusting the pH of the solution to 4.0–6.5, preferably 4.5–5.5, and mixing thoroughly. An organic receiving phase is then spread on the solution surface to introduce bubble mass transfer. After flotation, a uranium-loaded organic phase is obtained by separation. The uranium-loaded organic phase is then back-extracted to obtain a high-concentration clean uranium liquid. The flotation agent is composed of a mixture of an extractant and an alkaline solution, wherein the extractant is an acidic organophosphorus extractant.

[0007] In this invention, uranium extraction by flotation utilizes the specific binding effect of flotation extraction reagents with uranium ions to form a uranium-loaded hydrophobic complex in the aqueous phase; then, gas bubbles and an organic receiving phase are introduced into the solution for mass transfer, so that a metal-loaded oil layer is formed on the surface of the aqueous phase; and a high-purity target metal salt solution is obtained by back-extracting the oil layer.

[0008] As a preferred embodiment, the present invention provides a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the uranium concentration in the low-concentration uranium liquid is less than 1 g / L.

[0009] As a preferred embodiment, the present invention provides a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the flotation reagent is a microemulsion generated by mixing and emulsifying an extractant with an alkaline solution.

[0010] This invention discloses a method for uranium extraction from low-concentration uranium liquid via flotation extraction. The extractant is an acidic organophosphorus extractant, specifically selected from at least one of dibutyl phosphate, di(2-ethylhexyl) phosphate, and 2-ethylhexyl mono(2-ethylhexyl) phosphate. As a further preferred embodiment, the extractant is dibutyl phosphate.

[0011] This invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, magnesium hydroxide, and ammonia solution.

[0012] This invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the organic receiving phase is at least one selected from kerosene, n-hexane, cyclohexane, benzene, toluene, or alcohols.

[0013] One of the key aspects of this invention lies in the selection and modified preparation of the flotation extraction reagent. The flotation extraction reagent is formed by saponification of a mixture with an alkaline solution. The resulting Me-flotation extraction reagent possesses the same phosphoric acid extraction functional group as the extractant (Me is a metal cation or ammonium ion). After saponification, the resulting Me-flotation extraction reagent emulsion exhibits increased ductility, decreased viscosity, and increased hydrophilicity, thereby significantly improving the efficiency of uranium flotation extraction. Furthermore, this emulsion can maintain its emulsion state for an extended period, facilitating storage and transportation.

[0014] This invention discloses a method for uranium extraction via flotation extraction from low-concentration uranium liquid. A flotation reagent is added to the low-concentration uranium liquid, with the product ratio of the added flotation reagent to the pretreated low-concentration uranium liquid being 0.00008~0.1:1, preferably 0.0001~0.001:1. In industrial applications, a processing time of 3 minutes or more is sufficient. To ensure uranium recovery rate and efficiency, the single flotation time is generally controlled to 5~60 minutes. During the exploration process, it was also found that if the proportion of the added flotation reagent is too high, such as greater than 0.05, the uranium recovery rate will actually decrease.

[0015] The present invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the volume ratio of the organic receiving phase to the low-concentration uranium liquid is 0.001~0.2:1, preferably 0.05~0.2:1.

[0016] This invention discloses a method for extracting uranium from low-concentration uranium liquid via flotation extraction. During flotation extraction, the temperature is 20~40℃, although room temperature is also applicable to this invention.

[0017] This invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid, wherein the volume ratio of uranium-rich organic phase to stripping agent during the stripping process is 0.1~2.

[0018] This invention discloses a method for uranium extraction by flotation extraction of low-concentration uranium liquid. The back-extraction process involves thoroughly mixing a uranium-rich organic phase with a back-extraction agent and separating the liquids to obtain a high-concentration clean uranium liquid. The back-extraction agent is at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, or nitric acid solution.

[0019] The preferred stripping agent in the stripping process is ammonium bicarbonate, and the preferred ratio is 1 to 1.5, that is, the volume ratio of uranium-rich organic phase to stripping agent in the stripping process is 1 to 1.5.

[0020] This invention discloses a method for extracting uranium from low-concentration uranium liquid via flotation extraction. The uranium-loaded organic phase is repeatedly used as an organic receiving phase n times to obtain a uranium-rich organic phase, where n is a positive integer greater than or equal to 1.

[0021] This invention discloses a method for extracting uranium from a low-concentration uranium liquid using flotation extraction, which involves 1-3 stages of back-extraction from a uranium-rich organic phase to obtain a high-concentration clean uranium liquid.

[0022] This invention discloses a method for the separation and enrichment of uranium via flotation extraction. The flotation extraction process requires the formation of a stable uranium-loaded hydrophobic complex. Specifically, this involves controlling the volume ratio of the flotation extractant to the uranium-containing liquid to be 0.00008~0.1:1, preferably 0.0001~0.001:1, while simultaneously adjusting the pH of the aqueous phase to 4~6.5, preferably 4.5~5.5, to obtain a microemulsion phase containing the uranium hydrophobic complex. Then, the volume ratio of the organic receiving phase to the microemulsion is controlled to be 0.001~0.2:1, preferably (0.5~2)×10⁻⁶. -1 At a temperature of 10-60°C, gas is introduced to allow hydrophobic complexes in the microemulsion to enter the organic receiving phase, forming a loaded metal oil phase. Specifically, the back-extraction process involves controlling the ratio of the uranium-rich oil phase to the back-extracting agent to be 0.1-2, preferably 0.5-2, for mixed back-extraction. After settling, the supernatant is taken as a uranium salt solution. The back-extracting agent is one of sodium carbonate, ammonium bicarbonate, or nitric acid. These salt solutions all possess anions with high affinity for uranyl cations, which facilitates the entry of uranium from the oil phase into the aqueous phase.

[0023] In flotation extraction, dibutyl phosphate is the preferred flotation reagent, and sodium hydroxide is the preferred alkaline solution. Dibutyl phosphate is a byproduct of the production process of tributyl phosphate and has the advantages of low price and high extraction efficiency. Sodium hydroxide has the advantages of low price and environmental friendliness compared with other alkaline solutions.

[0024] This invention discloses a method for uranium enrichment through flotation extraction. The low-concentration uranium solution typically originates from radioactive water bodies generated by mining and nuclear industries, with a uranium concentration usually below 1 g / L. The acid-base adjuster is a hydrochloric acid and sodium hydroxide solution with a concentration of 0.2–2 mol / L; the back-extraction agent has a concentration of 0.1–1 mol / L. During the flotation extraction process, the volume ratio of reagents to the aqueous phase is 10:1.-4 ~10 -3 It consumes less solvent than conventional solvent extraction.

[0025] This invention combines the advantages of foam extraction and solvent extraction to prepare an amphiphilic flotation extractant. This agent achieves the extraction and enrichment of uranium from low-concentration uranium wastewater with ultra-low phase ratio and high enrichment ratio. The clean, high-concentration uranium solution obtained through back-extraction can be further used as a raw material for the nuclear industry. This invention possesses unique advantages such as high mass transfer efficiency, low energy consumption, low cost, and a mild reaction process, significantly improving the recovery efficiency of low-concentration uranium solutions, reducing reagent usage, and opening up new avenues for resource recycling. Detailed Implementation

[0026] The present invention will be further described in detail below through embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0027] Example 1

[0028] Uranium-containing wastewater from the mining of a associated uranium deposit, with a uranium concentration of 0.3 mg / L, was used as the subject. First, a flotation extraction reagent was prepared by shear emulsification of dibutyl phosphate and sodium hydroxide at a molar ratio of 1:1. This reagent was then mixed with the uranium-containing wastewater to obtain a uranium-loaded microemulsion. The pH of the solution was adjusted with 0.2–2 mol / L hydrochloric acid and sodium hydroxide, and the mixture was thoroughly mixed. Finally, gas was introduced into the solution, and flotation extraction was performed for 20 min using sulfonated kerosene at a volume ratio of 1:10 to the uranium-containing wastewater to obtain a uranium-rich oil phase. The obtained uranium-rich oil phase was back-extracted with 1 mol / L sodium bicarbonate at an oil-water ratio of 1:1, with a stirring speed of 200 rpm for 20 min. After settling and phase separation, a clean uranium liquid was obtained in the lower layer.

[0029] Following the above method, after single-stage flotation extraction of uranium-containing wastewater, under conditions of a flotation extraction reagent to uranium-containing wastewater volume ratio of 1:10000, pH=5, and a gas flow rate of 50 mL / min, the final aqueous phase contains 3 μg / L of uranium and can be directly discharged, with a uranium flotation extraction rate of 99%. After back-extraction, the uranium-rich oil phase contains 2.90 mg / L of uranium in the clean uranium solution.

[0030] Example 2

[0031] Other conditions were the same as in Example 1, except that uranium-containing wastewater with a uranium concentration of 330 μg / L was used as the treatment object. Under the conditions of a flotation extractant-water volume ratio of 1:10000, pH=5, a sulfonated kerosene-to-uranium-containing wastewater volume ratio of 1:10, and a gas flow rate of 50 mL / min, the wastewater was treated continuously for 10 times (each treatment lasted 20 min) without replacing the sulfonated kerosene, thus achieving the treatment of a large volume of wastewater.

[0032] The uranium flotation rates for treating uranium-containing wastewater using the above method were 95.9%, 96.7%, 97.2%, 96.3%, 96.6%, 94.7%, 95.6%, 95.4%, 95.3%, and 95.7%, respectively. The uranium concentration in the treated solution was below 15 μg / L, and the uranium concentration in the obtained oil phase reached 28.8 mg / L. The uranium-rich oil phase underwent one to two stages of back-extraction to obtain clean uranium liquid. These results demonstrate that the organic receiving phase in flotation extraction technology has a large capacity and can be recycled multiple times, allowing uranium to continuously accumulate in the surface solvent, ultimately potentially producing uranium liquid with a high enrichment ratio, providing qualified raw materials for the nuclear industry. Simultaneously, the amount of organic phase can be controlled at a very low level, significantly reducing the cost of wastewater resource utilization and ensuring the economic feasibility of industrial application.

[0033] Example 3

[0034] All other conditions are the same as in Example 1, except that: Uranium-containing wastewater with a uranium concentration of 1 mg / L was used as the target. Under the conditions of a uranium flotation extraction reagent to uranium-containing wastewater volume ratio of 1:10000, pH=5, a sulfonated kerosene to uranium-containing wastewater volume ratio of 1:10, and a gas flow rate of 50 mL / min, uranium was separated by single-stage flotation extraction for 20 min, achieving a uranium flotation extraction rate of 98%, yielding a uranium-rich oil phase. The uranium-rich oil phase was then subjected to single-stage back-extraction using ammonium bicarbonate as the back-extraction agent, achieving a back-extraction rate of 97%, resulting in clean uranium liquid.

[0035] After treatment using the above method, the uranium content in the raffinate aqueous phase was 20 μg / L. After back-extraction, a clean uranium solution with a uranium content of 9.8 mg / L was obtained. This method is more efficient than traditional extraction processes, has a wider processing range, and produces a high-purity clean uranium solution.

[0036] Exploring Case Group 1 In the exploratory case, the type of flotation agent, the amount of flotation agent, or the pH of the solution were not within the preferred range. Using the same uranium-containing wastewater as in Example 1, three sets of single-factor experiments were conducted, and the results of single-stage flotation extraction are shown in Table 1.

[0037] 1. Keeping all other conditions unchanged, change the flotation agent to di(2-ethylhexyl) phosphate; 2. Keeping other conditions constant, change the volume ratio of the flotation extraction reagent to the uranium-containing wastewater to 1:10; 3. Keeping other conditions constant, change the solution pH to 6 for three sets of experiments.

[0038] Table 1. Uranium recovery rates under different conditions via flotation extraction

[0039] Note: V in Table 1 水 This represents the volume of uranium-containing wastewater used.

[0040] Table 1 shows that the type, dosage, and pH of the flotation extraction reagent all have a certain impact on the flotation extraction efficiency. In Example 1, the optimal experimental conditions for flotation extraction were dibutyl phosphate, a flotation extraction reagent to uranium-containing wastewater volume ratio of 1:10000, and pH=5.

[0041] Exploring Case Group 2 In this exploratory case group, the type of stripping agent was not within the preferred range.

[0042] The uranium-rich oil phase from Example 1 was used. The uranium-rich oil phase was back-extracted using 1 mol / L nitric acid and sodium carbonate at O / A=1. The back-extraction rate and uranium content in the back-extraction solution are shown in Table 2.

[0043] Table 2. Results of back-extraction of uranium-rich oil

[0044] Table 2 shows that ammonium bicarbonate has the best stripping effect on uranium among the three stripping agents. The optimal experimental conditions are to use ammonium bicarbonate for 1-2 stages of stripping in the uranium-rich oil phase after flotation extraction.

[0045] In summary, through comparative analysis of the examples, flotation extraction technology can effectively extract uranium from low-concentration uranium-containing solutions of varying concentrations and significantly improve uranium separation efficiency. Furthermore, this technology consumes minimal reagents, is simple to operate, and is suitable for industrial-scale production.

Claims

1. Add the flotation reagent to the low-concentration uranium liquid, adjust the pH of the solution to 4.0~6.5, and mix thoroughly; introduce bubble mass transfer and organic receiving phase, spread a layer of organic receiving phase on the surface of the solution, bubble in the solution to make it float clear, and obtain the uranium-loaded organic phase by separation; back-extract the uranium-loaded organic phase to obtain a high-concentration clean uranium liquid. The flotation agent is composed of a mixture of an extractant and an alkaline solution, wherein the extractant is an acidic organophosphorus extractant.

2. The method for extracting uranium from low-concentration uranium liquid using flotation extraction according to claim 1, characterized in that: The uranium concentration in the low-concentration uranium liquid is less than 1 g / L.

3. The method for extracting uranium from low-concentration uranium liquid using flotation extraction according to claim 1, characterized in that: The flotation agent is a microemulsion produced by mixing and emulsifying the extractant with an alkaline solution.

4. A method for extracting uranium from low-concentration uranium liquid using flotation extraction according to any one of claims 1 and 3, characterized in that: The extractant is selected from at least one of dibutyl phosphate, di(2-ethylhexyl) phosphate, and 2-ethylhexyl mono(2-ethylhexyl) phosphate; the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, magnesium hydroxide, and ammonia solution; and the organic receiving phase is at least one of kerosene, n-hexane, cyclohexane, benzene, toluene, or alcohols.

5. The method for extracting uranium from low-concentration uranium liquid by flotation extraction according to claim 1, characterized in that: The back-extraction process involves thoroughly mixing the uranium-rich organic phase with the back-extraction agent and separating the liquids to obtain a high-concentration clean uranium liquid; the back-extraction agent is at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, or nitric acid solution.

6. A method for extracting uranium from low-concentration uranium liquid using flotation extraction according to claims 1 and 5, characterized in that: The volume ratio of the flotation reagent to the low-concentration uranium liquid is 0.0001~0.1; the volume ratio of the organic receiving phase to the low-concentration uranium liquid is 0.001~0.2; and the volume ratio of the uranium-rich organic phase to the back-extraction agent during the back-extraction process is 0.1~2.

7. The method for extracting uranium from low-concentration uranium liquid using flotation extraction according to claim 1, characterized in that: This loaded uranium organic phase is repeatedly used as an organic receiving phase n times to obtain a uranium-rich organic phase, where n is a positive integer greater than or equal to 1.

8. The method for extracting uranium from low-concentration uranium liquid by flotation extraction according to claim 1, characterized in that: High-concentration clean uranium liquid is obtained by performing 1-3 stages of back-extraction on uranium-rich organic phases.

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