Method for treating uranium-containing waste liquid

Abstract

The application discloses a treatment method of uranium-containing waste liquid. The treatment method comprises the following steps: passing the uranium-containing waste liquid through a macroporous chelating resin to obtain adsorbed resin; wherein a functional group is modified on the macroporous chelating resin, and the functional group is an amino carboxylic acid; wherein the uranium concentration in the uranium-containing waste liquid is 5-30 g / L, and the nitric acid concentration is 3-7 mol / L. The treatment method can effectively reduce the uranium content in the waste liquid.

Description

Technical Field

[0001] This invention relates to a method for treating uranium-containing waste liquid. Background Technology

[0002] With the development of the nuclear industry, a large amount of uranium-containing wastewater is inevitably generated. Uranium-containing wastewater possesses certain chemical toxicity and long-term radioactive hazards, which can adversely affect human health and the ecological environment. Furthermore, uranium is a primary fuel for nuclear energy development and utilization, and direct discharge would result in enormous waste. Therefore, finding a simple and reliable method to separate and recover U(VI) from uranium-containing wastewater is of great significance for human health and environmental protection.

[0003] Currently, commonly used methods for separating and recovering U(VI) from wastewater include electrolysis, chemical precipitation, solvent extraction, ion exchange, and adsorption. Generally, extraction is preferred for high-concentration uranium-containing wastewater, while adsorption is more economical and effective for low-concentration uranium-containing wastewater. Resins are commonly used adsorption materials, but current resins used in uranium-containing wastewater treatment suffer from drawbacks such as small adsorption capacity and poor treatment efficiency. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for treating uranium-containing waste liquid, which can effectively reduce the uranium content in the waste liquid. Furthermore, the treatment method has a high leaching rate, and uranium is easily separated from the resin.

[0005] This invention provides a method for treating uranium-containing waste liquid, comprising the following steps:

[0006] The uranium-containing waste liquid was passed through a macroporous chelating resin to obtain the adsorbed resin.

[0007] The macroporous chelating resin is modified with functional groups, wherein the functional groups are aminocarboxylic acids;

[0008] The concentration of uranium in the uranium-containing waste liquid is 5–30 g / L, and the concentration of nitric acid is 3–7 mol / L.

[0009] The uranium-containing wastewater of this invention can be distillation wastewater containing uranium and nitric acid. The concentration of uranium is 5–30 g / L; preferably 8–15 g / L. The concentration of nitric acid is 3–7 mol / L; preferably 4–6 mol / L.

[0010] According to the processing method of the present invention, preferably, the macroporous chelating resin uses a styrene-divinylbenzene copolymer as its backbone, and the benzene ring of the styrene-divinylbenzene copolymer is modified with the following functional groups:

[0011]

[0012] Where n is an integer selected from 1 to 12.

[0013] In the styrene-divinylbenzene copolymer, at least a portion of the hydrogen atoms on the benzene ring are replaced by the functional groups described above. In some embodiments, the hydrogen atom attached to the carbon atom at the para position of styrene in the styrene-divinylbenzene copolymer is replaced by the functional groups described above.

[0014] According to the processing method of the present invention, preferably, n is selected from an integer from 3 to 6.

[0015] According to one embodiment of the present invention, n is 4.

[0016] The macroporous chelating resin of the present invention can be prepared by reacting resin chlorine beads with aminocarboxylic acid to obtain macroporous chelating resin.

[0017] Aminocarboxylic acids can have the following structures:

[0018]

[0019] Wherein, n is selected from an integer from 1 to 12; preferably, n is selected from an integer from 3 to 6; according to one embodiment of the present invention, n is 4. According to one embodiment of the present invention, the aminocarboxylic acid is DL-lysine.

[0020] The resin chlorine beads are microspheres formed from chloromethylated styrene-divinylbenzene copolymer. Resin chlorine beads are commercially available or can be obtained by reacting styrene-divinylbenzene copolymer microspheres with chloromethyl ether. The chlorine content in the resin chlorine beads can be 10–25%; preferably 15–20%.

[0021] The mass ratio of resin chlorine balls to aminocarboxylic acid can be (1-3):1; preferably (1.5-2.5):1.

[0022] The reaction temperature between the resin chlorine balls and aminocarboxylic acid can be 70–95°C; preferably 80–90°C. The reaction time can be 8–20 h; preferably 10–15 h.

[0023] Specifically, the process includes the following steps: The resin chlorine beads are stirred and swollen in a solvent to obtain a mixture. The mixture is then reacted with an aminocarboxylic acid to obtain a macroporous chelating resin.

[0024] The solvent may include water and methanol. The volume ratio of water to methanol may be (2-6):(3-7); preferably (3-5):(4-6).

[0025] The swelling temperature can be 40–80℃; preferably 50–70℃. The swelling time can be 2–8 hours; preferably 3–6 hours.

[0026] The reaction product obtained by reacting resin chlorine balls with aminocarboxylic acid can be filtered and washed with water to obtain macroporous chelating resin.

[0027] Macroporous chelating resin is soaked in nitric acid to obtain macroporous chelating wet resin. The concentration of nitric acid can be 2-5 mol / L; preferably 3-4 mol / L. The soaking time can be 8-20 h; preferably 10-15 h.

[0028] According to the processing method of the present invention, preferably, the macroporous chelating resin is a macroporous chelating resin pretreated with nitric acid.

[0029] In some embodiments, the method further includes the following step: shaking the macroporous chelating wet resin in nitric acid to obtain a macroporous chelating resin pretreated with nitric acid.

[0030] The concentration of nitric acid is 1–3 mol / L; preferably 1.5–2.5 mol / L. The volume ratio of macroporous chelating wet resin to nitric acid is 1:(1–3); preferably 1:(1.5–2). The shaking speed is 100–400 r / min; preferably 150–300 r / min. The shaking temperature is 20–35℃; preferably 25–30℃. The shaking time is 8–20 h; preferably 10–15 h.

[0031] Macroporous chelating resin can be placed in a resin column. Preferably, the uranium-containing waste liquid flows in from the bottom of the resin column, and the treated waste liquid is discharged from the top of the resin column. A peristaltic pump can be used to pump the uranium-containing waste liquid into the resin column.

[0032] In this invention, unless otherwise specified, BV represents the resin volume.

[0033] The flow rate of uranium-containing waste liquid through the macroporous chelating resin is 0.1–1.5 BV / h; preferably 0.4–1 BV / h; more preferably 0.5–0.8 BV / h. This can reduce the uranium concentration in the treated waste liquid.

[0034] According to the treatment method of the present invention, preferably, the flow rate of uranium-containing waste liquid through the macroporous chelating resin is 0.1 to 1.5 BV / h;

[0035] The macroporous chelating resin is placed in a resin column, and the uranium-containing waste liquid flows in from the lower end of the resin column. After treatment, the waste liquid is discharged from the upper end of the resin column.

[0036] The macroporous chelating resin of this invention has a high adsorption capacity for uranium, and the amount of uranium-containing waste liquid treated per unit volume of resin is relatively large. The total volume of uranium-containing waste liquid treated by the macroporous chelating resin can be expressed as V. 0 < V ≤ 15 BV; preferably, 5 ≤ V ≤ 10 BV; more preferably, 8 ≤ V ≤ 9 BV. When V is less than or equal to 9 BV, the concentration of uranium in the treated waste liquid is below 1.5 μg / L.

[0037] According to the processing method of the present invention, preferably, the total volume of uranium-containing waste liquid through macroporous chelating resin is represented by V, where 0 < V ≤ 15 BV.

[0038] According to the processing method of the present invention, preferably, it further includes the following steps:

[0039] (A) The adsorbed resin is washed with water to obtain the first water-washed resin.

[0040] (B) Pass the alkali metal hydroxide solution through the resin after the first water washing to obtain the resin after the first alkali washing;

[0041] (C) Wash the resin after the first alkali washing with water to obtain the resin after the second water washing.

[0042] (D) Rinse the resin after the second water wash with an alkali metal carbonate solution and collect the rinsing solution.

[0043] In step (A), the amount of water used can be 1–5 BV; preferably 2–3 BV. The cleaning time can be 5–40 min; preferably 20–35 min.

[0044] In step (B), the pH of the alkali metal hydroxide solution after passing through the resin in the first water wash is 5 to 6.5; preferably, the pH is 5.5 to 6.

[0045] The pH of the alkali metal hydroxide solution can be 9–11; preferably 10–10.5. The alkali metal hydroxide can be selected from one or more of NaOH or KOH. According to one embodiment of the present invention, the alkali metal hydroxide is NaOH.

[0046] The flow rate of the resin after the alkali metal hydroxide solution passes through the first water wash can be 1 to 7 BV / min; preferably 4 to 6 BV / min.

[0047] In step (C), the amount of water used can be 1–5 BV; preferably 2–3 BV. The cleaning time can be 5–40 min; preferably 20–35 min.

[0048] In step (D), the concentration of the alkali metal carbonate solution can be 5–20 wt%; preferably 8–15 wt%. The alkali metal carbonate can be selected from one or more of sodium carbonate and potassium carbonate. According to one embodiment of the present invention, the alkali metal carbonate is sodium carbonate.

[0049] According to the processing method of the present invention, preferably, in step (A), the amount of water used is 1 to 5 BV, and the cleaning time is 5 to 40 min;

[0050] In step (B), the pH of the alkali metal hydroxide solution after passing through the resin in the first water wash is 5 to 6.5, the pH of the alkali metal hydroxide solution is 9 to 11, and the flow rate of the alkali metal hydroxide solution after passing through the resin in the first water wash is 1 to 7 BV / min.

[0051] In step (C), the amount of water used is 1 to 5 BV, and the cleaning time is 5 to 40 minutes;

[0052] In step (D), the concentration of the alkali metal carbonate solution is 5–20 wt%.

[0053] The alkali metal carbonate solution can be introduced from the bottom to the top, meaning the alkali metal carbonate solution enters from the bottom of the resin column and the eluent exits from the top of the resin column.

[0054] The flow rate of the resin after the alkali metal carbonate solution passes through the second water wash can be 1 to 5 BV / h; preferably 1.5 to 3 BV / h.

[0055] The amount of alkali metal carbonate solution used can be 3.5–10 BV; preferably 4.5–5.5 BV; more preferably 5 BV. This allows for the separation of most of the uranium from the resin while obtaining a highly enriched eluent.

[0056] According to the processing method of the present invention, preferably, the amount of alkali metal carbonate solution used is 3.5 to 10 BV; the alkali metal carbonate solution is introduced from bottom to top.

[0057] The treatment method of this invention can effectively reduce the uranium content in waste liquid. The resin of this invention has a high adsorption capacity, and a unit volume of resin can treat a large amount of uranium-containing waste liquid. Furthermore, this treatment method has a high leaching rate, uranium is easily separated from the resin, and a leaching solution with a high uranium enrichment can be obtained. Detailed Implementation

[0058] The testing method is described below:

[0059] Test method for uranium concentration: EJ / T 1235-2008 Determination of uranium content in uranium products by iron(II) reduction / potassium dichromate oxidation titration method.

[0060] The raw materials are described below:

[0061] The resin chlorine balls were purchased from Zhejiang Zhengguang Industrial Co., Ltd., with a chlorine content of 17% and a molecular weight of 30,000 to 50,000.

[0062] Preparation Example 1

[0063] 20g of resin chlorine beads were placed in a 500mL three-necked round-bottom glass flask, followed by the addition of 40mL of water and 50mL of methanol. The mixture was stirred and swollen at 60℃ for 4 hours to obtain a mixture. 10g of DL-lysine was added to the mixture, and the temperature was raised to 85℃ for 12 hours to obtain the reaction product. The reverse product was filtered and then washed with 200mL of deionized water to obtain macroporous chelating resin. The macroporous chelating resin was soaked in 3mol / L nitric acid for 12 hours to obtain wet macroporous chelating resin.

[0064] Preparation Example 2

[0065] 300 mL of the macroporous chelating wet resin obtained by the method in Preparation Example 1 was placed in 500 mL of 2 mol / L nitric acid and shaken at 200 r / min for 12 h at 25 °C to obtain the macroporous chelating resin pretreated with nitric acid.

[0066] Example 1

[0067] The uranium-containing waste liquid was pumped into the lower end of a resin column containing 300 mL of macroporous chelating resin pretreated with nitric acid, prepared according to the method of Preparation Example 2, using a peristaltic pump. The treated waste liquid was discharged from the upper end of the resin column. The uranium concentration in the uranium-containing waste liquid was 10 g / L, the nitric acid concentration was 5 mol / L, and the flow rate of the uranium-containing waste liquid was 0.5 BV / h.

[0068] The treated waste liquid was collected using an automated sampler, with each 1 BV collected as one sample. Specifically, samples from 0 to 1 BV were collected as one sample, numbered 1 BV; samples from 1 (excluding) to 2 BV were collected as one sample, numbered 2 BV; samples from 2 (excluding) to 3 BV were collected as one sample, numbered 3 BV; and so on, for a total of 10 BV of treated waste liquid collected. The uranium concentration in each sample is shown in Table 1 below.

[0069] Table 1

[0070] Sample number Uranium concentration 1BV 0.358 μg / L 2BV 0.957 μg / L 3BV 0.698 μg / L 4BV 0.325 μg / L 5BV 1.320 μg / L 6BV 1.119 μg / L 7BV 1.324 μg / L 8BV 0.355 μg / L 9BV 0.531 μg / L 10BV 412μg / L

[0071] As shown in Table 1, when the treatment volume is less than or equal to 9 BV, the uranium concentration in the treated waste liquid is below 1.5 μg / L; when the treatment volume is 10 BV, the uranium concentration in the treated waste liquid is 412 μg / L. Therefore, the method of this invention can effectively reduce the uranium concentration in uranium-containing waste liquid, and the resin used in this invention has good adsorption performance for uranium.

[0072] Example 2

[0073] The resin obtained in Example 1 was washed with 3BV deionized water for 30 minutes to obtain the first water-washed resin.

[0074] A NaOH solution with pH 10 was passed through the resin after the first water washing at a flow rate of 5 BV / min until the pH of the washing solution reached 5.8, thus obtaining the resin after the first alkali washing.

[0075] The resin after the first alkali washing was washed with 3BV deionized water for 30 minutes to obtain the resin after the second water washing.

[0076] The resin after the second water wash was rinsed with a 10 wt% sodium carbonate solution, with the inlet being at the bottom and the outlet at the top. The rinsing solution was collected. The flow rate of the sodium carbonate solution through the resin after the second water wash was 1.5 BV / h.

[0077] The eluent was collected as follows: Samples were collected from 0 to 1 BV, designated A; thereafter, samples were collected every 0.5 BV, i.e., samples from 1 (excluding) to 1.5 BV were designated B; samples from 1.5 (excluding) to 2 BV were designated C; samples from 2 (excluding) to 2.5 BV were designated D; and so on, for a total of 6 BV of eluent collected. The uranium concentration in each sample is shown in Table 2 below.

[0078] Table 2

[0079] Sample number Test results (g / L) A(0-1BV) 32.3 B(1-1.5BV) 50.7 C(1.5-2BV) 50.7 D(2-2.5BV) 51.1 E(2.5-3BV) 51.2 F(3-3.5BV) 26.8 G(3.5-4BV) 8.42 H(4-4.5BV) 5.59 I(4.5-5 BV) 1.87 G(5-5.5BV) 1.19 K(5.5-6BV) 0.718

[0080] As shown in Table 2, the method of the present invention has a high rinsing rate, easily separates uranium from the resin, and can effectively recover uranium from the waste liquid.

[0081] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for treating uranium-containing waste liquid, characterized in that, Includes the following steps: Uranium-containing waste liquid was pumped into the lower end of a resin column containing 300 mL of macroporous chelating resin pretreated with nitric acid using a peristaltic pump. The treated waste liquid was discharged from the upper end of the resin column, yielding the adsorbed resin. The uranium-containing waste liquid has a uranium concentration of 10 g / L, a nitric acid concentration of 5 mol / L, and a flow rate of 0.5 BV / h. The total volume of the uranium-containing waste liquid passing through the macroporous chelating resin is denoted by V, where V = 9 BV. The adsorbed resin was washed with 3 BV of deionized water for 30 min to obtain the first water-washed resin. NaOH solution with pH 10 was passed through the first water-washed resin at a flow rate of 5 BV / min until the pH of the washing solution reached 5.8, resulting in the first alkali-washed resin. The first alkali-washed resin was then washed with 3 BV of deionized water for 30 min to obtain the second water-washed resin. The second water-washed resin was rinsed with a 10 wt% sodium carbonate solution, with the inlet flow rate being bottom-in and the outlet flow rate being top-out. The rinsing solution was collected. The flow rate of sodium carbonate solution through the second water-washed resin was 1.5 BV / h, and the volume of sodium carbonate solution used was 5.5 BV. Where BV represents the volume of the macroporous chelating resin; The macroporous chelating resin pretreated with nitric acid was prepared by the following method: 20g of resin chlorine beads were placed in a 500 mL three-necked round-bottom glass flask, then 40 mL of water and 50 mL of methanol were added. The mixture was stirred and swollen at 60℃ for 4 h to obtain a mixture. 10g of DL-lysine was added to the mixture, and the temperature was raised to 85℃ for 12 h to obtain a reaction product. The reaction product was filtered and then washed with 200 mL of deionized water to obtain a macroporous chelating resin. The macroporous chelating resin was soaked in 3 mol / L nitric acid for 12 h to obtain a macroporous chelating wet resin. 300 mL of macroporous chelating wet resin was placed in 500 mL of 2 mol / L nitric acid and shaken at 200 r / min for 12 h at 25 °C to obtain macroporous chelating resin pretreated with nitric acid.

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