Method for leaching uranium from tantalum-niobium slag

Abstract

The invention discloses a method for leaching uranium from tantalum-niobium slag, which comprises the following steps: step 1, putting the tantalum-niobium slag into a reactor loaded with water, sequentially adding a preset amount of sodium carbonate, sodium bicarbonate and sodium hypochlorite, controlling the pH value in the solution to be 9-10.5, and heating and reacting at 80-90 DEG C for 14-36 hours to obtain leached slurry, the liquid-solid ratio of the volume of the added water to the tantalum-niobium slag is (1-2) mL: 1g, and the adding mass of the sodium hypochlorite solution is 2%-6% of the mass of the tantalum-niobium slag; 2, the leaching slurry is filtered, and leaching liquid and leaching residues are obtained; step 3, adding a sodium hydroxide solution into the leachate, and filtering to obtain yellow cake precipitate and filtrate; and step 4, adding sodium bicarbonate with a preset mass into the filtrate, and then refluxing the obtained mixed solution of sodium carbonate and sodium bicarbonate into the step 1. The invention aims to simplify the uranium leaching process flow of the tantalum-niobium slag so as to reduce the cost investment.

Description

Technical Field

[0001] The invention relates to the technical field of tantalum-niobium ore smelting, and in particular to a method for leaching uranium from tantalum-niobium slag. Background Art

[0002] The original tantalum-niobium ore is subjected to high-concentration HF / H2SO4 mixed leaching / ore extraction to extract tantalum and niobium, and then acid recovery, defluorination and neutralization are used to form tantalum-niobium ore extraction tailings. The main components of the slag are: Sn, Fe, Zr, F, SO4 2- ,Si,U.

[0003] The existing invention patent with patent publication number CN117551894A discloses a method for improving the uranium leaching rate in tantalum-niobium ore extraction residue, which preliminarily adds tantalum-niobium ore extraction residue to lime milk for mixing, and fully stirs until the pH value of the mixed slurry is 6.5±0.2, so that sulfate and fluoride ions entrained in the residue are precipitated, and then sedimentation separation is performed, and the obtained slurry is added to a carbonate solution and ozone is introduced, and the stirring is continued for 3h to 6h at 60°C to 97°C, and the pH value is controlled to be 10.2 to 10.4. Although the uranium leaching rate in the tantalum-niobium ore extraction residue can be improved, the entire treatment process is complicated and the cost investment is high. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for leaching uranium from tantalum-niobium slag, aiming to solve the technical problem that the existing tantalum-niobium slag uranium leaching process has low cost performance.

[0005] To achieve the above object, the present invention provides a method for leaching uranium from tantalum-niobium slag, the method comprising the following steps:

[0006] Step 1, placing the tantalum-niobium slag in a reactor loaded with water, and sequentially adding a preset amount of sodium carbonate, sodium bicarbonate and sodium hypochlorite, and controlling the pH of the solution to be between 9 and 10.5, and heating the solution at 80° C. to 90° C. for 14 to 36 hours to obtain a leaching slurry, wherein the volume of the added water and the liquid-solid ratio of the tantalum-niobium slag are (1 to 2) mL: 1 g, and the added mass of the sodium hypochlorite solution is 2% to 6% of the mass of the tantalum-niobium slag;

[0007] Step 2, filtering the leached slurry to obtain a leaching solution and a leaching residue;

[0008] Step 3, adding sodium hydroxide solution to the leaching solution, and filtering to obtain yellow cake precipitate and filtrate;

[0009] Step 4: adding a preset mass of sodium bicarbonate to the filtrate, and then refluxing the obtained sodium carbonate and sodium bicarbonate mixture into step 1.

[0010] Optionally, before step 3, the method further includes:

[0011] Determining the uranium content of the leaching solution in step 2;

[0012] When the uranium content of the leaching solution exceeds 5-8 g / L in step 2, step 3 is performed;

[0013] Otherwise, the leachate obtained by filtration in step 2 is refluxed into step 1.

[0014] Optionally, in step 1, the total mass of sodium carbonate and sodium bicarbonate is 40%-60% of the mass of the tantalum-niobium slag.

[0015] Optionally, in step 1, the mass ratio of sodium carbonate to sodium bicarbonate is 7:1 to 5:1.

[0016] Optionally, step 2 further includes washing the obtained leaching residue with water for multiple times to obtain entrained leachate, and incorporating the first washing water into the leachate.

[0017] Optionally, in step 1, the volume of the mixed solution and the liquid-solid ratio of the tantalum-niobium slag are 1.2 mL: 1 g.

[0018] Optionally, in step 1, the total mass of sodium carbonate and sodium bicarbonate is 50% of the mass of the tantalum-niobium slag.

[0019] Optionally, in step 1, the mass ratio of sodium carbonate to sodium bicarbonate is 5:1.

[0020] Optionally, the heating in step 1 is carried out by water bath heating.

[0021] Beneficial effects:

[0022] (1) Sodium carbonate, sodium bicarbonate and sodium hypochlorite are reacted with tantalum-niobium slag at 80°C to 90°C for 14 to 36 hours. Most of the uranium in the tantalum-niobium ore tailings exists in the form of uranium tetrafluoride. Sodium hypochlorite can accelerate the oxidation of the tantalum-niobium tailings. At the same time, uranyl ions react with hydroxides under alkaline conditions to form diuranate precipitation. The diuranate then reacts with carbonates to form uranyl tricarbonate ions that dissolve in the leachate. That is, the leaching of uranium in the tantalum-niobium slag is achieved through the synergistic effect of sodium carbonate, sodium bicarbonate and sodium hypochlorite.

[0023] (2) Real-time monitoring of the uranium content in the filtered leachate to determine whether sodium hydroxide precipitation is needed. When the uranium content is less than 5g / L, it can be returned to the leaching process to increase the uranium content by adding new tantalum-niobium slag for leaching treatment multiple times. When the uranium content of the leachate exceeds 5-8g / L, sodium hydroxide precipitation is performed to avoid unnecessary waste when the uranium content is low. The filtrate after re-filtration is returned to the leaching process after adding sodium bicarbonate, which greatly reduces the amount of wastewater and ensures product quality.

[0024] (3) The entire processing process is simple, convenient and easy to operate, thereby reducing cost investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic flow diagram of an embodiment of a method for leaching uranium from tantalum-niobium slag of the present invention;

[0026] Figure 2 for Figure 1 The flow chart shown.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0029] See also Figure 1-2 The present invention provides a schematic flow diagram of a method for leaching uranium from tantalum-niobium slag, the method comprising the following steps:

[0030] Step 1: Place the tantalum-niobium slag in a reactor loaded with distilled water, and add a preset amount of sodium carbonate, sodium bicarbonate and sodium hypochlorite in sequence, and react at 80°C to 90°C for 14 to 36 hours to obtain a leaching slurry. The tantalum-niobium slag is the ore leached with high-concentration HF / H2SO4, tantalum and niobium are extracted from the ore, and the tantalum-niobium ore tailings are formed after acid recovery, defluorination and neutralization. The main components are: Sn, Fe, Zr, F, SO4 2- The total mass of sodium carbonate and sodium bicarbonate added to Si and U is 40%-60% of the mass of tantalum-niobium slag, the mass of sodium hypochlorite solution added is 2%-6% of the mass of tantalum-niobium slag, and the volume of water added and the liquid-solid ratio of tantalum-niobium slag are (1-2) mL: 1g, thereby controlling the pH in the leaching slurry to be 9-10.5. The reaction mechanism in this step is that most of the uranium in the tantalum-niobium ore tailings exists in the form of uranium tetrafluoride, and sodium hypochlorite can accelerate the oxidation of tantalum-niobium tailings. At the same time, under alkaline conditions, uranyl ions react with hydroxide to form diuranate precipitation, and diuranate reacts with carbonate to form uranyl tricarbonate ions dissolved in the leachate to achieve uranium leaching. The reaction equation is as follows:

[0031] UF4+ClO - +2OH-→UO2 2+ +Cl-+4F - +2H2O;

[0032]

[0033] Na2U2O7+6(HCO3) -→2[UO2(CO3)3] 4- +2Na + +3H2O.

[0035] Preferably, the heating in step 1 is carried out in a water bath.

[0036] Step 2, filtering the leached slurry to obtain a leaching solution and a leaching residue; wherein the iron in the tantalum-niobium slag will consume the alkali but will not enter the alkaline leaching solution, but will exist in the leaching residue in the form of precipitation.

[0037] Step 3, adding sodium hydroxide solution to the leaching solution, and filtering to obtain yellow cake precipitate and filtrate;

[0038] Step 4, adding a preset mass of sodium bicarbonate to the filtrate, and then refluxing the obtained sodium carbonate and sodium bicarbonate mixture into step 1, so that the filtrate after re-filtration is returned to the leaching after adding sodium bicarbonate, the amount of wastewater is greatly reduced, and the product quality is guaranteed.

[0039] The invention adopts sodium carbonate, sodium bicarbonate and sodium hypochlorite to react with tantalum-niobium slag at 80-90°C for 14-36 hours. Based on the fact that most uranium in the tantalum-niobium ore extraction tailings exists in the form of uranium tetrafluoride, the oxidation of the tantalum-niobium tailings can be accelerated by sodium hypochlorite. At the same time, under alkaline conditions, uranyl ions react with hydroxide to form diuranate precipitation, and the diuranate reacts with carbonate to form uranyl tricarbonate ions that are dissolved in the leaching solution. That is, the leaching of uranium in the tantalum-niobium slag is achieved through the synergistic effect of sodium carbonate, sodium bicarbonate and sodium hypochlorite.

[0040] Furthermore, before step 3, the method further includes:

[0041] Determining the uranium content of the leaching solution in step 2;

[0042] When the uranium content of the leaching solution exceeds 5-8 g / L in step 2, step 3 is performed.

[0043] Otherwise, the leaching solution filtered in step 2 is returned to step 1, and the uranium content is enhanced by adding new tantalum-niobium slag for multiple times to avoid unnecessary waste when the uranium content is low.

[0044] Furthermore, in step 1, the mass ratio of sodium carbonate to sodium bicarbonate is 7:1 to 5:1, preferably, the mass ratio of sodium carbonate to sodium bicarbonate is 5:1.

[0045] Furthermore, in step 1, the volume of the mixed solution and the liquid-solid ratio of the tantalum-niobium slag are 1.2 mL: 1 g.

[0046] Furthermore, in step 1, the total mass of sodium carbonate and sodium bicarbonate is 50% of the mass of the tantalum-niobium slag.

[0047] Furthermore, step 2 also includes washing the obtained leaching residue with water for multiple times to obtain the entrained leachate, and merging the first washing water into the leachate. Specifically, washing is performed three times with water at a temperature of 85°C. The first washing water and the leachate are combined to form a filtrate, and the second and third washing waters are mixed to form a washing water. The filtrate and washing water are sent for analysis to measure the uranium content. The leaching residue is filtered and washed and weighed, and then weighed again after drying at 105°C. After drying, the residue is sampled and sent for analysis to measure the uranium content.

[0048] Furthermore, the sodium hypochlorite solution used in step 1 is 500 mL of commercially available analytically pure sodium hypochlorite solution.

[0049] In addition, in order to better illustrate the process and effect of a method for leaching uranium from tantalum-niobium slag, the following is a detailed description through specific examples, the details are as follows:

[0050] Example 1

[0051] 175 g of sodium carbonate, 35 g of sodium bicarbonate, 500 g of ore sample, 600 mL of water and 20 mL of NaClO were added into the reactor, heated in a water bath at 90 °C and stirred to react for 14 h, and the leachate and filter residue were obtained by filtration. The filter residue was washed three times with water at 85 °C, the first washing water was added into the leachate, and the second and third washing waters were mixed as washing water. The leachate and washing water were sent for analysis to measure the uranium content.

[0052] The leached residue was weighed after filtration and washing, and then weighed again after drying at 105°C. After drying, the residue was sampled and sent for analysis to measure the uranium content. It was found that the U content in the washing water was 0.28g / L, the U content in the leaching solution was 1.12g / L (less than 5g / L), the wet residue weighed 837.2g, the dry residue weighed 530.61g, the grade U was 0.04%, and the leaching rate was 92.09%.

[0053] The filtered leachate is refluxed to the leaching step to continue the reaction.

[0054] Example 2

[0055] 208 g of sodium carbonate, 42 g of sodium bicarbonate, 500 g of ore sample, 600 mL of water and 20 mL of NaClO were added into a reactor, heated in a water bath at 90 ° C and stirred to react for 14 h, and the leachate and filter residue were obtained by filtration. The filter residue was washed three times with water at a temperature of 85 ° C. The first washing water was added to the leachate, and the second and third washing waters were mixed as washing water. The leachate and washing water were sent for analysis to measure the uranium content.

[0056] The leached residue was weighed after filtration and washing, and then weighed again after drying at 105℃. After drying, the residue was sampled and sent for analysis to measure the uranium content. It was found that the U content in the washing water was 0.13g / L, the U content in the leaching solution was 0.67g / L (less than 5g / L), the wet residue weighed 826.41g, the dry residue weighed 536.34g, the grade U was 0.03%, and the leaching rate was 94.07%.

[0057] The filtered leachate is refluxed to the leaching step to continue the reaction.

[0058] Example 3

[0059] 175 g of sodium carbonate, 25 g of sodium bicarbonate, 500 g of ore sample, 600 mL of water and 20 mL of NaClO were added into the reactor, heated in a water bath at 90 °C and stirred to react for 24 h, and the leachate and filter residue were obtained by filtration. The filter residue was washed three times with water at 85 °C, the first washing water was added into the leachate, and the second and third washing waters were mixed as washing water. The leachate and washing water were sent for analysis to measure the uranium content.

[0060] The leached residue was filtered and washed, weighed, and then weighed again after drying at 105°C. After drying, the residue was sampled and sent for analysis to measure the uranium content. The U content in the washing water was 1.54g / L, the U content in the leaching solution was 5.8g / L (greater than 5g / L), the wet residue weighed 1094g, the dry residue weighed 537.4g, the grade U was 0.136%, and the leaching rate was 73.12%.

[0061] Continue to add sodium hydroxide solution to the leachate, and after filtering, obtain yellow cake precipitate and filtrate, add sodium bicarbonate to the filtrate, and then reflux the obtained sodium carbonate and sodium bicarbonate mixed solution to the leaching step.

[0062] Example 4

[0063] 208 g of sodium carbonate, 42 g of sodium bicarbonate, 500 g of ore sample, 600 mL of water and 20 mL of NaClO were added into a reactor, heated in a water bath at 80 °C and stirred to react for 36 h, and the leachate and filter residue were obtained by filtration. The filter residue was washed three times with water at 85 °C, the first washing water was added to the leachate, and the second and third washing waters were mixed to form the washing water. The leachate and washing water were sent for analysis to measure the uranium content.

[0064] The leached residue was weighed after filtration and washing, and then weighed again after drying at 105℃. After drying, the residue was sampled and sent for analysis to measure the uranium content. It was found that the U content in the washing water was 1.78g / L, the U content in the leaching solution was 6.6g / L (greater than 5g / L), the wet residue weighed 934.62g, the dry residue weighed 586.33g, the grade U was 0.115%, and the leaching rate was 77.27%.

[0065] Continue to add sodium hydroxide solution to the leachate, and after filtering, obtain yellow cake precipitate and filtrate, add sodium bicarbonate to the filtrate, and then reflux the obtained sodium carbonate and sodium bicarbonate mixed solution to the leaching step.

[0066] Example 5

[0067] Take the filtrate obtained after the second filtration in the previous cycle, add sodium bicarbonate to the filtrate, analyze the mixture of sodium carbonate and sodium bicarbonate, and obtain the CO3 2- 188.35g / L,HCO3 - 3.99g / L, 500mL of sodium carbonate and sodium bicarbonate mixture, 42g of sodium carbonate, 20g of sodium bicarbonate, 500g of ore sample, 100mL of water and 20mL of NaClO were added into the reactor, heated in a water bath at 90℃ and stirred to react for 36h, and the leachate and filter residue were obtained by filtration. The filter residue was washed three times with water at 85℃, the first washing water was added into the leachate, the second and third washing water were mixed as washing water, and the leachate and washing water were sent for analysis to measure the uranium content.

[0068] The leached residue was weighed after filtration and washing, and then weighed again after drying at 105℃. After drying, the residue was sampled and sent for analysis to measure the uranium content. It was found that the U content in the washing water was 0.95g / L, the U content in the leaching solution was 3.2g / L (less than 5g / L), the wet residue weighed 867.7.62g, the dry residue weighed 582.87g, the grade U was 0.065%, and the leaching rate was 87.15%.

[0069] The filtered leachate is refluxed to the leaching step to continue the reaction.

[0070] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0071] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0072] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for leaching uranium from tantalum-niobium slag, characterized in that: The method comprises the following steps: Step 1, placing the tantalum-niobium slag in a reactor loaded with water, and sequentially adding a preset amount of sodium carbonate, sodium bicarbonate and sodium hypochlorite, and controlling the pH of the solution to be between 9 and 10.5, and heating the solution at 80° C. to 90° C. for 14 to 36 hours to obtain a leaching slurry, wherein the volume of the added water and the liquid-solid ratio of the tantalum-niobium slag are (1 to 2) mL: 1 g, and the added mass of the sodium hypochlorite solution is 2% to 6% of the mass of the tantalum-niobium slag; Step 2, filtering the leached slurry to obtain a leaching solution and a leaching residue; Step 3, adding sodium hydroxide solution to the leaching solution, and filtering to obtain yellow cake precipitate and filtrate; Step 4: adding a preset mass of sodium bicarbonate to the filtrate, and then refluxing the obtained sodium carbonate and sodium bicarbonate mixture into step 1.

2. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: Also include before step 3: Determining the uranium content of the leaching solution in step 2; When the uranium content of the leaching solution exceeds 5-8 g / L in step 2, step 3 is performed; Otherwise, the leachate obtained by filtration in step 2 is refluxed into step 1.

3. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: In step 1, the total mass of sodium carbonate and sodium bicarbonate is 40%-60% of the mass of the tantalum-niobium slag.

4. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: In step 1, the mass ratio of sodium carbonate to sodium bicarbonate is 7:1 to 5:

1.

5. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: Step 2 also includes washing the obtained leaching residue with water for multiple times to obtain entrained leachate, and incorporating the first washing water into the leachate.

6. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: In step 1, the volume of the mixed solution and the liquid-to-solid ratio of the tantalum-niobium slag are 1.2 mL:1 g.

7. The method for leaching uranium from tantalum-niobium slag according to claim 5, characterized in that: In step 1, the total mass of sodium carbonate and sodium bicarbonate is 50% of the mass of the tantalum-niobium slag.

8. The method for leaching uranium from tantalum-niobium slag according to claim 4, characterized in that: In step 1, the mass ratio of sodium carbonate to sodium bicarbonate is 5:

1.

9. The method for leaching uranium from tantalum-niobium slag according to claim 1, characterized in that: The heating in step 1 is carried out in a water bath.

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