A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid

Abstract

The present invention relates to the technical field of nuclear fuel assembly manufacturing and specifically discloses a process for recovering uranium and fluorine from uranium-containing hydrofluoric acid. The process comprises the following steps: Step 1: hydrofluoric acid precipitation and separation; Step 2: uranium recovery and treatment; and Step 3: fluorine and ammonia recovery and treatment. After treatment using the process, the uranium content in the wastewater can be reduced to 0.08 mg / L, fluoride ions are converted into deionized calcium fluoride, and ammonia ions are recovered through ammonia distillation and can be recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear fuel assembly manufacturing, and in particular relates to a process for recovering uranium and fluorine from uranium-containing hydrofluoric acid. Background Art

[0002] During the IDR chemical conversion process for nuclear fuel element manufacturing, a certain amount of substandard hydrofluoric acid (uranium content: greater than 5 mg / L, hydrofluoric acid content: 30% to 40%) is produced. Currently, there is no mature treatment process for this substandard hydrofluoric acid containing uranium. Traditionally, uranium removal from wastewater relies on direct exchange adsorption. However, when treating uranium in hydrofluoric acid, the adsorbent material is not resistant to hydrofluoric acid corrosion, and the uranium content after treatment does not meet emission standards (emission requirements: uranium content below 0.08 mg / L).

[0003] Therefore, it is urgent to design a process for recovering uranium and fluorine in uranium-containing hydrofluoric acid to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a process for recovering uranium and fluorine in uranium-containing hydrofluoric acid and to effectively treat unqualified hydrofluoric acid wastewater.

[0005] The technical solutions of the present invention are as follows:

[0006] A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid comprises the following steps:

[0007] Step 1: Hydrofluoric acid precipitation and separation

[0008] 1.1. Add uranium-containing hydrofluoric acid and ammonia water into the precipitation tank in sequence to carry out uranium precipitation reaction;

[0009] 1.2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process;

[0010] Step 2: Uranium recovery and processing

[0011] The uranium ions in the filtrate are replaced on the resin through the ion exchange tower, so that the uranium concentration in the filtrate is lower than 0.08 mg / L and meets the requirements;

[0012] Step 3: Recovery of fluorine and ammonia

[0013] 3.1. The filtrate with qualified uranium ions undergoes precipitation reaction to complete the transformation of ammonia and fixation of fluoride ions;

[0014] 3.2. After precipitation, the slurry is distilled in a distillation tower to separate the ammonium ions in the slurry, and then absorbed by deionized water to obtain ammonia water with a qualified concentration;

[0015] 3.3. After ammonia recovery, the slurry is centrifuged to obtain a filter cake, which is then dried to produce calcium fluoride powder;

[0016] Finally, the fluoride ions and ammonium ions in the filtrate are analyzed and discharged after passing the test.

[0017] Step 2 specifically includes the following:

[0018] 2.1. Add production water and ammonia water to the filtrate after separation to adjust the fluorine content and pH value;

[0019] 2.2. The adjusted uranium-containing filtrate enters the ion exchange tower, and the uranium ions in the filtrate are replaced on the resin, so that the uranium concentration in the filtrate is lower than 0.08 mg / L and meets the requirements.

[0020] In step 2.1, the fluorine content is adjusted to below 30 g / L and the pH value is adjusted to 9-10.

[0021] In step 2.2, the flow rate was controlled at 700-1000 L / h.

[0022] In step 1.1, the precipitation process temperature is controlled at 50-70° C., the precipitation time is 2-3 h, and the pH value after the reaction is 8-9.

[0023] In step 3.1, Ca(OH)2 slurry is added to the filtrate with qualified uranium ions to carry out precipitation reaction to complete the transformation of ammonia and fixation of fluoride ions.

[0024] In step 3.1, the molar concentration of the Ca(OH)2 slurry is controlled to be 5-10% excess.

[0025] In step 3.1, the precipitation temperature is 60-70°C and the time is 1-2 hours.

[0026] In step 3.2, the distillation temperature is 90-110° C., and the distillation pressure is 1-4 kPa.

[0027] In step 3.3, the drying process temperature is 90-120°C.

[0028] The remarkable effects of the present invention are:

[0029] (1) The present invention establishes a process for recovering uranium and fluorine from hydrofluoric acid, providing a new process for treating uranium-containing hydrofluoric acid produced during uranium chemical conversion.

[0030] (2) After treatment by the process of the present invention, the uranium content in the final wastewater can be reduced to 0.08 mg / L, and the fluoride ions are converted into controlled calcium fluoride. During the process, the ammonia ions can be recycled after being recovered by ammonia evaporation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process flow chart. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid is shown, comprising the following steps:

[0034] Step 1: Hydrofluoric acid precipitation and separation

[0035] 1.1. Add uranium-containing hydrofluoric acid and ammonia water into the precipitation tank in sequence to carry out uranium precipitation reaction. The precipitation process temperature is controlled at 50-70°C, the precipitation time is 2-3 hours, and the pH value after the reaction is 8-9;

[0036] 1.2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process;

[0037] Step 2: Uranium recovery and processing

[0038] 2.1. Add production water and ammonia water to the filtrate after separation to adjust the fluorine content and pH value;

[0039] Adjust the fluoride content to below 30g / L and the pH value to 9-10;

[0040] 2.2. The adjusted uranium-containing filtrate enters the ion exchange tower to replace the uranium ions in the filtrate onto the resin. The flow rate is controlled at 700-1000 L / h to make the uranium concentration in the filtrate lower than 0.08 mg / L and meet the requirements.

[0041] Step 3: Recovery of fluorine and ammonia

[0042] 3.1. Add Ca(OH)2 slurry to the fluorine-containing and ammonia-containing filtrate with qualified uranium ions, controlling the molar concentration of Ca(OH)2 slurry to be 5-10% excess, and carry out precipitation reaction to complete the transformation of ammonia and fixation of fluoride ions;

[0043] The precipitation temperature is 60-70°C and the time is 1-2 hours;

[0044] 3.2. After precipitation, the slurry is distilled in a distillation tower to separate the ammonium ions in the slurry, and then absorbed by deionized water to obtain ammonia water with a qualified concentration;

[0045] Distillation temperature 90~110℃, distillation pressure 1~4kPa;

[0046] 3.3. After ammonia recovery, the slurry is centrifuged to obtain a filter cake, which is then dried to produce calcium fluoride powder; the drying process temperature is 90-120°C;

[0047] Finally, the fluoride ions and ammonium ions in the filtrate are analyzed and discharged after passing the test.

[0048] Example 1

[0049] A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid comprises the following steps:

[0050] Step 1: Hydrofluoric acid precipitation and separation

[0051] 1.1. Hydrofluoric acid and ammonia water were added to the precipitation tank in sequence to carry out uranium precipitation reaction. The precipitation process temperature was controlled at 50°C and the precipitation time was 2 hours. The pH value after the reaction was 8.5.

[0052] 1.2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process;

[0053] Step 2: Uranium recovery and processing

[0054] 2.1. Add production water and ammonia water to the separated filtrate to adjust the fluorine content to 28g / L and the pH value to 10;

[0055] 2.2. The adjusted uranium-containing wastewater enters the ion exchange tower to replace the uranium ions in the wastewater onto the resin. The flow rate is controlled at 800L / h to keep the uranium concentration in the wastewater below 0.08mg / L.

[0056] Step 3: Recovery of fluorine and ammonia

[0057] 3.1. Add Ca(OH)2 slurry to the fluorine-containing and ammonia-containing wastewater with qualified uranium ions, control the molar concentration of Ca(OH)2 slurry to be 8% excess, and carry out precipitation reaction at 60°C for 1 hour to complete the transformation of ammonia and fixation of fluoride ions;

[0058] 3.2. After precipitation, the slurry is distilled in a distillation tower at a distillation temperature of 100°C and a distillation pressure of 2kPa to separate the ammonium ions in the slurry, which are then absorbed by deionized water to obtain ammonia water of qualified concentration;

[0059] 3.3. After ammonia recovery, the slurry is centrifuged and the filter cake is dried at a temperature of 110°C to produce calcium fluoride powder;

[0060] The filtrate is analyzed for fluoride ions and ammonium ions and discharged after passing the test.

[0061] Example 2

[0062] A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid comprises the following steps:

[0063] Step 1: Hydrofluoric acid precipitation and separation

[0064] 1.1. Hydrofluoric acid and ammonia water were added to the precipitation tank in sequence to carry out uranium precipitation reaction. The precipitation process temperature was controlled at 60°C and the precipitation time was 2.5 hours. The pH value after the reaction was 9.

[0065] 1.2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process;

[0066] Step 2: Uranium recovery and processing

[0067] 2.1. Add production water and ammonia water to the filtrate after separation to adjust the fluorine content to 30g / L and the pH value to 9;

[0068] 2.2. The adjusted uranium-containing wastewater enters the ion exchange tower to replace the uranium ions in the wastewater onto the resin. The flow rate is controlled at 700 L / h to keep the uranium concentration in the wastewater below 0.08 mg / L.

[0069] Step 3: Recovery of fluorine and ammonia

[0070] 3.2. Add Ca(OH)2 slurry to the fluorine-containing and ammonia-containing wastewater with qualified uranium ions, control the molar concentration of Ca(OH)2 slurry to be 10% excess, and carry out precipitation reaction at 70℃ for 2 hours to complete the transformation of ammonia and fixation of fluoride ions;

[0071] 3.2. After precipitation, the slurry is distilled in a distillation tower at a distillation temperature of 100°C and a distillation pressure of 1.5 kPa to separate the ammonium ions in the slurry, which are then absorbed by deionized water to obtain ammonia water of qualified concentration;

[0072] 3.3. After ammonia recovery, the slurry is centrifuged and the filter cake is dried at a temperature of 100°C to produce calcium fluoride powder;

[0073] The filtrate is analyzed for fluoride ions and ammonium ions and discharged after passing the test.

[0074] Example 3

[0075] A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid comprises the following steps:

[0076] Step 1: Hydrofluoric acid precipitation and separation

[0077] 1.1. Hydrofluoric acid and ammonia water were added to the precipitation tank in sequence to carry out uranium precipitation reaction. The precipitation process temperature was controlled at 70°C, the precipitation time was 3 hours, and the pH value after the reaction was 9;

[0078] 1.2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process;

[0079] Step 2: Uranium recovery and processing

[0080] 2.1. Add production water and ammonia water to the filtrate after separation to adjust the fluorine content to 30g / L and the pH value to 10;

[0081] 2.2. The adjusted uranium-containing wastewater enters the ion exchange tower to replace the uranium ions in the wastewater onto the resin. The flow rate is controlled at 1000 L / h to keep the uranium concentration in the wastewater below 0.08 mg / L.

[0082] Step 3: Recovery of fluorine and ammonia

[0083] 3.3. Add Ca(OH)2 slurry to the fluorine-containing and ammonia-containing wastewater with qualified uranium ions, control the molar concentration of Ca(OH)2 slurry to be 10% excess, and carry out precipitation reaction at a temperature of 70°C for 1 hour to complete the transformation of ammonia and fixation of fluoride ions;

[0084] 3.2. After precipitation, the slurry is distilled in a distillation tower at a distillation temperature of 90°C and a distillation pressure of 1 kPa to separate the ammonium ions in the slurry, which are then absorbed by deionized water to obtain ammonia water of qualified concentration;

[0085] 3.3. After ammonia recovery, the slurry is centrifuged and the filter cake is dried at a temperature of 110°C to produce calcium fluoride powder;

[0086] The filtrate is analyzed for fluoride ions and ammonium ions and discharged after passing the test.

[0087] The above shows and describes the basic principles, main features and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0088] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A process for recovering uranium and fluorine from uranium-containing hydrofluoric acid, comprising the following steps: Step 1: Hydrofluoric acid precipitation and separation 1.

1. Add uranium-containing hydrofluoric acid and ammonia water into the precipitation tank in sequence to carry out uranium precipitation reaction; 1.

2. After precipitation, the slurry undergoes solid-liquid separation, the solid is oxidized and then barreled, and the filtrate enters the uranium recovery process; Step 2: Uranium recovery and processing The uranium ions in the filtrate are replaced on the resin through the ion exchange tower, so that the uranium concentration in the filtrate is lower than 0.08 mg / L and meets the qualified standard; Step 3: Recovery of fluorine and ammonia 3.

1. The filtrate with qualified uranium ions undergoes precipitation reaction to complete the transformation of ammonia and fixation of fluoride ions; 3.

2. After precipitation, the slurry is distilled in a distillation tower to separate the ammonium ions in the slurry, and then absorbed by deionized water to obtain ammonia water with a qualified concentration; 3.

3. After ammonia recovery, the slurry is centrifuged to obtain a filter cake, which is then dried to produce calcium fluoride powder; Finally, the fluoride ions and ammonium ions in the filtrate are analyzed and discharged after passing the test; In step 3.1, Ca(OH)2 slurry is added to the filtrate with qualified uranium ion concentration to carry out precipitation reaction to complete the transformation of ammonia and fixation of fluoride ions.

2. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 1, wherein step 2 specifically comprises the following: 2.

1. Add production water and ammonia water to the filtrate after separation to adjust the fluorine content and pH value; 2.

2. The adjusted uranium-containing filtrate enters the ion exchange tower, where the uranium ions in the filtrate are replaced on the resin, so that the uranium concentration in the filtrate is lower than 0.08 mg / L, meeting the qualified standard.

3. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 2, wherein: In step 2.1, the fluorine content was adjusted to below 30 g / L and the pH value was adjusted to 9-10.

4. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 2, wherein: In step 2.2, control the flow rate to 700~1000L / h.

5. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 1, wherein: In step 1.1, the precipitation process temperature is controlled at 50-70° C., the precipitation time is 2-3 h, and the pH value after the reaction is 8-9.

6. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 1, wherein: In step 3.1, the molar concentration of the Ca(OH)2 slurry is controlled to be 5-10% excess.

7. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 6, wherein: In step 3.1, the precipitation temperature is 60~70℃ and the time is 1~2h.

8. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 1, wherein: In step 3.2, the distillation temperature is 90~110°C, and the distillation pressure is 1~4KPa.

9. The process for recovering uranium and fluorine from uranium-containing hydrofluoric acid according to claim 1, wherein: In step 3.3, the drying process temperature is 90~120℃.

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