Process for recovering uranium from uranium-containing hydrofluoric acid waste liquid

Abstract

The invention belongs to the technical field of nuclear industry wastewater treatment, and particularly relates to a process for recycling uranium from uranium-containing hydrofluoric acid waste liquid. The process comprises the following steps: activating a special uranium removal ion exchange resin column by using an activating agent; filtering the uranium-containing hydrofluoric acid waste liquid, and then introducing the uranium-containing hydrofluoric acid waste liquid into an activated special uranium-removing ion exchange resin column for adsorption, so that the uranium concentration of tail water is reduced to be below 50 mu g / L; when the uranium concentration of the tail water is higher than 50 mu g / L, adsorption is stopped, and desorption operation is carried out; after desorption is completed, the special uranium removal ion exchange resin column is subjected to secondary blending, and the adsorption performance of the special uranium removal ion exchange resin column is recovered. According to the technology, the uranium-containing hydrofluoric acid waste liquid with the uranium content of about 2-30 mg / L is subjected to adsorption treatment through the special uranium removal ion exchange resin, and the uranium content of adsorption tail water can be reduced to 50 micrograms / L.

Description

Technical Field

[0001] This invention belongs to the field of nuclear industry wastewater treatment technology, specifically relating to a process for recovering uranium from uranium-containing hydrofluoric acid waste liquid. Background Technology

[0002] The uranium-to-UF4 conversion process inevitably generates a large amount of uranium-containing hydrofluoric acid waste liquid. This type of waste liquid is radioactive, classified as low-level radioactive waste, and typically contains 20%-30% hydrogen fluoride, with uranium concentrations reaching 2 mg / L-30 mg / L. Therefore, to avoid environmental pollution, this waste liquid must undergo rigorous uranium and fluoride removal treatment to meet relevant standards before it can be safely discharged.

[0003] Currently, uranium conversion plants treat this type of uranium-containing hydrofluoric acid wastewater using a lime precipitation process. This involves sending the uranium-containing hydrofluoric acid to a slaked lime precipitation reactor, where industrial lime is added and stirred for a neutralization reaction. During this process, fluoride ions in the wastewater combine with calcium ions to form calcium fluoride precipitate. Subsequently, the calcium fluoride precipitate is separated from the clarified liquid. The separated clarified liquid undergoes deep defluorination to ensure that the fluoride ion concentration in the discharged wastewater meets standards. The resulting calcium fluoride residue, due to its radioactivity, can only be disposed of in very low-level radioactive landfills. The uranium-containing hydrofluoric acid wastewater generated by the uranium conversion process has an acidity of approximately 30%. Neutralization treatment not only consumes a large amount of lime but also generates a large amount of fluoride-containing wastewater and calcium fluoride residue, undoubtedly creating difficulties for subsequent waste treatment and increasing operating costs. Summary of the Invention

[0004] The purpose of this application is to design a process for recovering uranium from uranium-containing hydrofluoric acid waste liquid. For uranium-containing hydrofluoric acid waste liquid with a uranium content of about 2-30 mg / L, a special uranium removal ion exchange resin is used for adsorption treatment, which can reduce the uranium content of the adsorbed tail water to 50 μg / L.

[0005] Technical solution to achieve the purpose of this application:

[0006] This application provides a process for recovering uranium from uranium-containing hydrofluoric acid waste liquid, comprising the following steps:

[0007] S1: Activate the special uranium removal ion exchange resin column using an activator;

[0008] S2: After filtration, the uranium-containing hydrofluoric acid waste liquid is passed into an activated special uranium removal ion exchange resin column for adsorption, so that the uranium concentration in the tail water is reduced to below 50 μg / L.

[0009] S3: When the uranium concentration in the tailwater exceeds 50 μg / L, adsorption is stopped and desorption is performed.

[0010] S4: After desorption is completed, the special uranium removal ion exchange resin column is re-adjusted to restore its adsorption performance.

[0011] Optionally, the matrix of the special uranium removal ion exchange resin is polystyrene, the functional groups include carboxyl and amino groups, the structure is a macroporous cross-bonded structure, the particle size is 0.5-0.9 mm, and the saturated uranium exchange capacity is 80-100 gU / L.

[0012] Optionally, the activator in S1 is a 1% hydrofluoric acid solution with a volume of 5 BV.

[0013] Optionally, a carbon steel-lined PTFE filter is used in S2, with a filtration accuracy of 1-5 μm.

[0014] Optionally, in S2, the feed flow rate of the uranium-containing hydrofluoric acid waste liquid is 1 BV / h.

[0015] Optionally, the desorption operation in S3 includes the following steps:

[0016] S301: Drain hydrofluoric acid waste liquid from the column;

[0017] S302: Use a special uranium removal ion exchange resin column to replace the production water until the pH of the effluent is 5;

[0018] S303: Adjust the pH inside the column to 8-9 using a 1% NaOH solution;

[0019] S304: Use a 10% Na2CO3 solution for desorption until the concentration of uranium in the desorbed water is below 50 mg / L.

[0020] Optionally, the secondary allocation in S4 includes the following steps:

[0021] S401: Use the production water to replace the special uranium removal ion exchange resin column until the effluent pH is 7;

[0022] S402: Adjust the pH of the column to 3-4 using a 1% HF solution.

[0023] The beneficial technical effects of this application are as follows:

[0024] (1) This invention innovatively proposes a process route for removing uranium from uranium-converted hydrofluoric acid waste liquid that is suitable for engineering applications, which can achieve the removal of uranium from hydrofluoric acid waste liquid.

[0025] (2) The ion exchange technology used in this invention can achieve an adsorption of uranium content in tailwater of less than 50 μg / L.

[0026] (3) The hydrofluoric acid solution obtained after the uranium removal treatment of uranium-containing hydrofluoric acid waste liquid using the ion exchange technology adopted in this invention can be utilized as a resource.

[0027] (4) The calcium fluoride slag formed after the uranium removal treatment of uranium-containing hydrofluoric acid waste liquid using the ion exchange technology of the present invention can be disposed of under controlled conditions. Detailed Implementation

[0028] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] This application provides a process for recovering uranium from uranium-containing hydrofluoric acid waste liquid, including the following steps:

[0030] S1: Activate the special uranium removal ion exchange resin column using an activator;

[0031] The ion exchange column is loaded with 70L of special uranium removal resin. Hydrofluoric acid with a volume concentration of 1% is prepared as an activator. The prepared hydrofluoric acid with a concentration of 1% is pumped into the ion exchange column. The activation volume of the hydrofluoric acid activator is 70L, which is approximately the amount of resin loaded in the ion exchange column.

[0032] S2: After filtration, the uranium-containing hydrofluoric acid waste liquid is passed into an activated special uranium removal ion exchange resin column for adsorption, so that the uranium concentration in the tail water is reduced to below 50 μg / L.

[0033] After the ion exchange column is activated, uranium-containing hydrofluoric acid waste liquid with an acidity of approximately 30% is pumped into a filter made of carbon steel lined with PTFE and a filtration accuracy of 1–5 μm to intercept impurities before entering the ion exchange column. The flow rate of the filtered uranium-containing hydrofluoric acid waste liquid entering the ion exchange column is controlled at 70 L / h, and the uranium content of the adsorption tail water is periodically sampled and analyzed. At this point, the uranium content of the adsorption tail water is less than 50 μg / L.

[0034] S3: When the uranium concentration in the tailwater exceeds 50 μg / L, adsorption is stopped and desorption is performed.

[0035] When the uranium content in the adsorbed tailwater exceeds 50 μg / L, the special uranium removal resin reaches its breakthrough point, at which point desorption is required.

[0036] S301: Drain hydrofluoric acid waste liquid from the column;

[0037] S302: Use production water to replace the special uranium removal ion exchange resin column until the effluent pH is 5; prepare a 1% NaOH solution as an alkaline conditioner, and first use production water to replace the acidic medium in the ion exchange column until the effluent pH reaches 5, which is considered as the replacement is complete.

[0038] S303: Adjust the pH of the column to 8-9 using a 1% NaOH solution; after the replacement is complete, pump the prepared 1% NaOH conditioning agent into the ion exchange column and measure the pH of the adsorption tail water periodically until the pH of the adsorption tail water is maintained at 8-9, which is considered as the end of alkaline conditioning.

[0039] S304: Use a 10% Na2CO3 solution for desorption until the uranium concentration in the effluent is below 50 mg / L. After the pH of the ion exchange column is adjusted, prepare a 10% Na2CO3 solution as the desorbent. Pump the prepared desorbent into the ion exchange column and periodically monitor the uranium content in the effluent. Desorption is considered complete when the uranium content in the effluent decreases to below 50 mg / L.

[0040] S4: After desorption is completed, the special uranium removal ion exchange resin column is re-adjusted to restore its adsorption performance;

[0041] S401: Use production water to replace the special uranium removal ion exchange resin column until the effluent pH is 7; after desorption, prepare a 1% HF solution as a pH acidity adjuster, and first use production water to replace the desorbent in the ion exchange column until the effluent pH reaches 7, which is considered as the replacement is complete.

[0042] S402: Adjust the pH of the column to 3-4 using a 1% HF solution. After replacement, pump the prepared acidic conditioning agent into the ion exchange column and periodically monitor the pH of the adsorption tailwater until it remains between 3 and 4, at which point the acid conditioning is considered complete. After acid conditioning, the ion exchange column recovers its adsorption performance and can be used for secondary adsorption. Pump the uranium-containing hydrofluoric acid waste liquid into the ion exchange column at a flow rate of 70 L / h and periodically sample and analyze the uranium content in the adsorption tailwater. At this point, the uranium content in the adsorption tailwater should be less than 50 μg / L.

[0043] The above embodiments have provided a detailed description of this application, but this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A process for recovering uranium from uranium-containing hydrofluoric acid waste liquid, characterized in that, Includes the following steps: S1: Activate the special uranium removal ion exchange resin column using an activator; S2: After filtration, the uranium-containing hydrofluoric acid waste liquid is passed into an activated special uranium removal ion exchange resin column for adsorption, so that the uranium concentration in the tail water is reduced to below 50 μg / L. S3: When the uranium concentration in the tailwater exceeds 50 μg / L, adsorption is stopped and desorption is performed. S4: After desorption is completed, the special uranium removal ion exchange resin column is re-adjusted to restore its adsorption performance.

2. The process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claim 1, characterized in that, The special uranium removal ion exchange resin has a polystyrene matrix, functional groups including carboxyl and amino groups, a macroporous cross-bonded structure, a particle size of 0.5-0.9 mm, and a saturated uranium exchange capacity of 80-100 gU / L.

3. The process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claim 2, characterized in that, The activator in S1 is a 1% hydrofluoric acid solution with a volume of 5 BV.

4. The process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claim 3, characterized in that, The S2 uses a carbon steel-lined PTFE filter with a filtration accuracy of 1-5μm.

5. The process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claim 4, characterized in that, In S2, the feed flow rate of the uranium-containing hydrofluoric acid waste liquid is 1 BV / h.

6. The process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claim 5, characterized in that, The desorption operation in S3 includes the following steps: S301: Drain hydrofluoric acid waste liquid from the column; S302: Use a special uranium removal ion exchange resin column to replace the production water until the pH of the effluent is 5; S303: Adjust the pH inside the column to 8-9 using a 1% NaOH solution; S304: Use a 10% Na2CO3 solution for desorption until the concentration of uranium in the desorbed water is below 50 mg / L.

7. A process for recovering uranium from uranium-containing hydrofluoric acid waste liquid according to claims 1-6, characterized in that, The secondary blending in S4 includes the following steps: S401: Use the production water to replace the special uranium removal ion exchange resin column until the effluent pH is 7; S402: Adjust the pH of the column to 3-4 using a 1% HF solution.