A method for removing uranium from a cobalt hydroxide enriched in uranium

Abstract

This invention relates to the field of cobalt hydroxide purification, specifically to a method for removing uranium from uranium-rich cobalt hydroxide: Uranium-rich cobalt hydroxide raw material is prepared by adding acid to form a cobalt-containing solution; ammonia solution, hexamethylenetetramine solution, and phosphoric acid solution are added sequentially to the cobalt-containing solution for uranium removal in series, yielding a uranium-removed solution. After solid-liquid separation, uranium-rich filter residue and a uranium-removed cobalt solution are obtained. This invention targets crude cobalt hydroxide products enriched with uranium. By using a series uranium removal method and selecting a combination of three precipitants, the co-precipitation of valuable metal cobalt and uranium is avoided, significantly reducing the loss of cobalt. Simultaneously, this method greatly improves the separation efficiency of uranium, reaching approximately 98%; the loss of cobalt metal is as low as 0.9%.

Description

Technical Field

[0001] This invention relates to the field of cobalt hydroxide purification, and more specifically to a method for removing uranium from uranium-rich cobalt hydroxide. Background Technology

[0002] Cobalt is widely used in lithium-ion batteries, high-temperature alloys, cemented carbides, catalysts, and other fields. With the rapid development of the new energy industry, global demand for cobalt resources continues to grow. Crude cobalt hydroxide (Co(OH)2) is a common intermediate product in cobalt hydrometallurgy, typically obtained from cobalt-containing leachates through neutralization precipitation. This product has advantages such as low production cost and ease of transportation, making it an important raw material for the subsequent preparation of high-purity cobalt salts or electrolytic cobalt.

[0003] The pH ranges for uranium and cobalt ion precipitation highly overlap. When a precipitant is added to raise the solution pH to 7.2, divalent cobalt ions and uranyl ions will precipitate. Simultaneously, the rapidly forming cobalt hydroxide precipitate is an amorphous or microcrystalline substance with a large specific surface area and high surface activity. It can firmly fix uranyl ions and their hydrolysis products in the solution within the solid through surface adsorption or lattice encapsulation. When the cobalt precipitation solution contains uranium ions, the crude cobalt hydroxide intermediate product from the cobalt precipitation process will be doped with a certain amount of uranium.

[0004] In non-ferrous metal ores, uranium, as a by-product radioactive element, can enter the solution system through the leaching of copper-cobalt ores. During the hydrometallurgical process of cobalt, the crude cobalt hydroxide product obtained after leaching and preliminary neutralization precipitation often contains uranium enriched in the raw materials. The presence of uranium not only reduces the quality of cobalt products but also poses environmental and safety risks due to excessive radioactivity, while simultaneously limiting the market application of the products.

[0005] Current uranium removal methods include solvent extraction, ion exchange, and chemical precipitation. Extraction methods use extractants (such as methyl isobutyl ketone) with low flash points (flammable) and toxicity, posing significant safety hazards. The process is lengthy and requires large-scale equipment. Furthermore, to improve separation efficiency, large amounts of salting-out agents are added, leading to a significant increase in the volume of radioactive organic waste liquid and making subsequent treatment difficult. Ion exchange is highly sensitive to pH changes; excessively acidic or alkaline conditions affect the resin's adsorption capacity and efficiency. If the feed solution contains suspended solids (e.g., turbidity up to 500 NTU), it can clog the resin bed, reducing flow rate and loading capacity. It also exhibits poor selectivity; the presence of numerous competing ions (such as chlorides and nitrates) in the solution further reduces the resin's uranium adsorption efficiency. Among chemical precipitation methods, phosphate precipitation is widely used, but this traditional method struggles to achieve quantitative uranium precipitation, leaving some uranium residue in the solution. When treating low-concentration uranium-containing solutions, it often suffers from high reagent consumption, poor uranium removal selectivity, and significant cobalt metal loss. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a uranium removal method for uranium-rich cobalt hydroxide with low cobalt loss and good uranium removal effect.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows: a method for removing uranium from uranium-rich cobalt hydroxide, comprising taking uranium-rich cobalt hydroxide raw material and adding acid to prepare a cobalt-containing solution with a pH value of 1.0~1.7; performing uranium removal in series on the cobalt-containing solution to obtain a uranium-removed solution; and performing solid-liquid separation on the uranium-removed solution to obtain uranium-rich filter residue and uranium-removed cobalt solution. The tandem uranium removal method involves: adding an ammonia solution to the cobalt-containing feed solution until the pH value is 3.8-3.9; then adding a hexamethylenetetramine solution until the pH value is 5.4-5.6; and finally adding a phosphoric acid solution until the pH value is 5.2-5.3 to obtain the uranium-removed feed solution.

[0008] Preferably, the uranium content in the cobalt-containing liquid is 10ppm to 15ppm.

[0009] Preferably, the temperature of the tandem uranium removal process is 39°C to 41°C.

[0010] Preferably, the mass ratio of crude cobalt hydroxide raw material to acid solution is 1:48~52.

[0011] Preferably, the acid solution is a sulfuric acid solution with a concentration of 14 g / L to 16 g / L.

[0012] Preferably, the concentration of the ammonia solution is 19wt% to 21wt%.

[0013] Preferably, the concentration of the hexamethylenetetramine solution is 4wt% to 6wt%.

[0014] Preferably, the concentration of the phosphoric acid solution is 0.8wt% to 1.2wt%.

[0015] Preferably, magnesium oxide is added to the uranium-removed cobalt solution to precipitate cobalt until the pH value reaches 7.18~7.22, followed by solid-liquid separation to obtain the uranium-removed cobalt hydroxide product.

[0016] Preferably, the temperature for cobalt deposition is 58°C to 62°C.

[0017] The present invention has the following beneficial effects: (1) For crude cobalt hydroxide products enriched with uranium, a series of uranium removal modes are used, and three precipitants are selected for combination to avoid co-precipitation of valuable metal cobalt and uranium, thus significantly reducing the loss of cobalt. At the same time, this method greatly improves the separation efficiency of uranium, with a separation efficiency of about 98%; the loss of cobalt metal is as low as less than 0.9%. (2) Ammonia water is selected to neutralize the residual acid, and at the same time, some impurity elements such as uranium, iron, and aluminum are separated as the first stage of uranium removal. Compared with the traditional process of using quicklime for neutralization, it can avoid the introduction of a large amount of calcium ions to react with sulfate or carbonate ions in the solution to form calcium sulfate or calcium carbonate precipitates. The slag rate of the solution impurity removal process is lower, which effectively avoids the loss of cobalt metal caused by mechanical entrainment. At the same time, ammonia water forms a complex with cobalt ions, reducing the loss of cobalt ions flowing into the sludge. (3) Using hexamethylenetetramine for secondary uranium removal, hexamethylenetetramine undergoes a selective complexation reaction, which directionally converts valuable cobalt metal into soluble stable complexes or compounds that enter the solution phase. At the same time, impurity elements are converted into insoluble compounds through precipitation reactions and enter the slag phase, thus achieving precise separation of target components and impurities. This not only significantly improves the selective extraction efficiency of valuable cobalt metal, but also effectively avoids its loss due to co-precipitation or mechanical entrainment. (4) Phosphoric acid is used as the tertiary uranium removal agent of the present invention. Since most of the impurity elements in the solution have been separated in the first and second stages, it can effectively reduce the competition between impurity elements and uranium elements for reaction with phosphoric acid in the tertiary uranium removal process, greatly improve the uranium removal efficiency, and at the same time reduce the amount of phosphoric acid used. (5) During the uranium removal process, the amount of slag produced by impurity precipitation was greatly reduced by using ammonia and hexamethylenetetramine instead of quicklime as pH adjusters, and the slag rate was reduced to less than 9%. This improvement effectively solved the problem of slag stockpiling, significantly reduced the cost of slag transfer and disposal, and also created favorable conditions for subsequent slag resource recovery or reuse. (6) During the uranium removal process, the added uranium removal agent also causes other impurity elements such as iron, manganese, calcium, and magnesium to co-precipitate with uranium and be removed; after cobalt precipitation, the impurity content in the product is significantly reduced and the cobalt grade is improved, thereby effectively improving the overall quality of the product.

[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of the uranium removal method of uranium-rich cobalt hydroxide in Embodiment 1 of the present invention. Detailed Implementation

[0020] To make the objectives, solutions, and beneficial technologies of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be noted that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.

[0021] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0022] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.

[0023] An embodiment of the present invention provides a method for uranium removal from uranium-rich cobalt hydroxide, comprising: taking uranium-rich cobalt hydroxide raw material and adding acid solution to prepare a pH value of 1.0-1.7; performing uranium removal in series on the cobalt-containing solution to obtain uranium-removed solution; and performing solid-liquid separation on the uranium-removed solution to obtain uranium-rich filter residue and uranium-removed cobalt solution. The tandem uranium removal method involves: adding an ammonia solution to the cobalt-containing feed solution until the pH value is 3.8-3.9; then adding a hexamethylenetetramine solution until the pH value is 5.4-5.6; and finally adding a phosphoric acid solution until the pH value is 5.2-5.3 to obtain the uranium-removed feed solution.

[0024] The principle behind this solution is as follows: (a) Redissolution of solid cobalt hydroxide raw material; adding acid can dissolve uranium-rich cobalt hydroxide solid. As the reaction proceeds, the cobalt ions (Co) in the solid... 2+ The reactants are released into the solution; as the reactants are continuously consumed, the solid gradually dissolves and disappears, yielding a cobalt-containing solution; the chemical reaction equation is: Co(OH)2 + 2H + →Co2 + + 2H2O For liquid cobalt hydroxide feedstock (uranium-containing cobalt solution), adding acid to adjust the pH value can obtain a cobalt-containing feedstock suitable for subsequent tandem uranium removal treatment; (II) Primary impurity and uranium removal: pH 3.8 is the endpoint or neutralization point for iron removal. The pH of the solution is adjusted to 3.8-3.9 by adding ammonia. This serves three purposes: first, to neutralize residual acid by using the alkalinity of ammonia; second, to separate some impurities such as iron and aluminum from the solution system; and third, under the conditions of pH 3.8-3.9, cobalt ions exist in the form of complex water and ions and will not undergo hydrolysis and precipitation. At this time, ammonia reacts with uranyl sulfate solution to form tetrahydrate basic uranyl sulfate precipitate, thus performing the initial separation of uranium. (1) Provide OH - Neutralize excess acid, slowly raise the pH value, and react the ammonia water (ammonia monohydrate, NH3·H2O) with the residual acid (H2O) in the cobalt-containing solution. + The reaction, depending on the molar ratio of the two, may produce two types of salts. When ammonia is in sufficient quantity, the reaction produces an ammonium salt; when ammonia is insufficient or acid is in excess, the reaction produces an acidic ammonium salt. Since the final pH value of the reaction is 3.8~3.9, the reaction environment is one of excess acid, thus producing an acidic ammonium salt. Taking sulfate as the anion as an example, the chemical formula is: NH3·H2O + H2SO4 → NH4HSO4 + H2O (2) Fe 3+ Precipitation begins at around pH 2-3, and is almost complete by pH 3.8-3.9; Al 3+ Precipitation begins at a pH of approximately 3.8–4.0, as the final pH of the reaction is 3.8–3.9, at which point the solution contains partially Al. 3+ It begins to settle, and Co 2+ At this point, it remains stable in solution; the chemical reaction equation is: Fe 3+ + 3NH3·H2O → Fe(OH)3↓ + 3NH4 + Al 3+ + 3NH3·H2O →Al(OH)3↓ + 3NH4 + (3) Under pH conditions of 3.8~3.9, ammonia reacts with uranyl solution to form hydrated basic uranyl precipitate, thus performing the initial separation of uranium. Taking sulfate as the anion as an example, the chemical reaction equation is: 2UO2SO4 + 2NH3H2O ​​+ 4H2O→ (UO2)2(OH)2SO44H2O↓+(NH4)2SO4 (III) Secondary uranium removal: Slowly add 5% hexamethylenetetramine solution to adjust the pH to 5.4-5.6. Hexamethylenetetramine will undergo a selective complexation reaction, directionally converting valuable cobalt metal into soluble stable complexes or compounds that enter the solution phase. At the same time, impurity elements will undergo precipitation reactions to form insoluble compounds that enter the slag phase, thereby achieving precise separation of the target component from impurities. First, hexamethylenetetramine undergoes a coordination reaction with cobalt ions to form soluble complexes, preventing cobalt metal from entering the slag in solid form. Second, as the pH reaches 5.4-5.6 with the addition of hexamethylenetetramine, hexamethylenetetramine reacts with uranyl ions to form gel microspheres, further achieving cobalt-uranium separation. (1) In the presence of ammonia or ammonium salts, hexamethylenetetramine reacts with cobalt ions in solution to eventually form a yellow hexamethylenetetramine cobalt complex (usually [Co(CH2)6N4)). 2+ (A complex-like compound) is slowly added until the pH value reaches 5.4-5.6, at which point the complexation reaction between hexamethylenetetramine and cobalt ions ceases; the equation for the complexation reaction process can be expressed as follows: Co 2+ + (CH2)6N4→ [Co(CH2)6N4) 2+ (2) Under pH conditions of approximately 5.4–5.6, the reaction mechanism of hexamethylenetetramine with uranium (usually existing in the form of acid-deficient uranyl nitrate) is a process in which the controlled decomposition of hexamethylenetetramine is used to uniformly increase the pH of the solution and initiate the gel precipitation of uranyl ions; the hydrolysis reaction of hexamethylenetetramine is a prerequisite for all subsequent precipitation reactions. (CH2)6N4 + 6H2O → 6HCHO + 4NH3 The ammonia produced by hydrolysis uniformly increases the pH value, causing uranyl ions to form a gel and precipitate (overall reaction formula): UO2 2+ +NH3 +3H2O→UO3·2H2O(gel)+NH4 + (iv) Three-stage uranium removal: Add phosphoric acid until the pH value reaches 5.2~5.3 and then stop. Although no calcium ions are introduced in the entire separation process, the raw material itself may contain a small amount of calcium ions, so the uranium removal may be converted into two solid precipitates: uranyl phosphate mineral and calcium uranium mica. Formation of uranyl phosphate precipitate (without calcium ions): When phosphoric acid is added directly to the solution, a yellow uranyl phosphate precipitate will form. 3 UO2 2+ +2PO4 3- + nH2O→(UO2)3(PO4)2 nH2O↓ Calcium-uranium mica (containing calcium ions) is formed. Ca2+ +2 UO2 2+ + 2PO4 3- + nH2O→Ca(UO2)2(PO4)2 nH2O↓ In the uranium-removing solution obtained after a series of uranium removal reactions, most of the uranium has entered the precipitate, while the cobalt element remains in the solution. Through solid-liquid separation, uranium-rich filter residue and uranium-removed cobalt solution can be obtained.

[0025] In some embodiments of the present invention, the uranium-rich cobalt hydroxide raw material is a crude cobalt hydroxide intermediate product obtained by leaching and neutralizing copper-cobalt ore with associated uranium during the cobalt hydrometallurgical process.

[0026] In some embodiments of the present invention, the uranium content in the cobalt-containing liquid is 10ppm to 15ppm.

[0027] In some embodiments of the present invention, the uranium content in the uranium-rich cobalt hydroxide raw material is 500ppm to 550ppm.

[0028] In some embodiments of the present invention, the temperature of the tandem uranium removal process is 39°C to 41°C.

[0029] In some embodiments of the present invention, the mass ratio of crude cobalt hydroxide raw material to acid solution is 1:48~52.

[0030] In some embodiments of the present invention, the acid solution is a sulfuric acid solution with a concentration of 14 g / L to 16 g / L.

[0031] In some embodiments of the present invention, the concentration of the ammonia solution is 19 wt% to 21 wt%.

[0032] In some embodiments of the present invention, the concentration of the hexamethylenetetramine solution is 4 wt% to 6 wt%.

[0033] In some embodiments of the present invention, the concentration of the phosphoric acid solution is 0.8 wt% to 1.2 wt%.

[0034] In some embodiments of the present invention, magnesium oxide is added to the uranium-removed cobalt solution to precipitate cobalt until the pH value is 7.18~7.22, and then solid-liquid separation is performed to obtain the uranium-removed cobalt hydroxide product.

[0035] In some embodiments of the present invention, magnesium oxide is introduced in the form of a suspension of 10wt% to 12wt%.

[0036] In some embodiments of the present invention, the cobalt deposition temperature is 58°C to 62°C.

[0037] In some embodiments of the present invention, the residue is washed after solid-liquid separation, and the washing liquid is combined with the filtrate. This reduces entrainment.

[0038] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0039] Example 1 In this embodiment, the uranium-rich cobalt hydroxide raw material is a crude cobalt hydroxide (Co(OH)2) intermediate product enriched with uranium from the raw material in the Democratic Republic of Congo. The chemical analysis results are shown in Table 1.

[0040] Table 1. Multi-element analysis results of crude cobalt hydroxide intermediate product in Example 1 The uranium removal method for uranium-rich cobalt hydroxide in this embodiment is as follows: Figure 1 As shown, the specific operation is as follows: (1) At a temperature of 40℃, weigh 10g of uranium-rich cobalt hydroxide raw material, add 500mL of 15g / L sulfuric acid solution to dissolve the crude cobalt hydroxide (the mass ratio of sulfuric acid solution to uranium-rich cobalt hydroxide raw material is about 50:1), stir thoroughly for 1 hour to ensure complete dissolution, and obtain a cobalt-containing solution with a pH value of 1.0. (2) At a temperature of 40°C, add 20wt% ammonia solution dropwise to the cobalt-containing solution and stir thoroughly to prevent local over-alkaliness until the pH of the solution is 3.8. (3) At a temperature of 40°C, slowly add 5 wt% hexamethylenetetramine solution to the liquid until the pH of the liquid is 5.5; (4) At a temperature of 40°C, add 1 wt% phosphoric acid solution dropwise to the solution until the pH value of the solution is 5.25. Stir for 30 minutes to ensure the reaction is complete and obtain the uranium removal solution. (5) The uranium-removing liquid is filtered to achieve solid-liquid separation. The filter residue is washed twice with clean water. The washing liquid is combined with the filtrate to obtain uranium-rich filter residue and uranium-removing cobalt solution. (6) Add 10wt% magnesium oxide emulsion to the uranium-removed cobalt solution to precipitate cobalt at a temperature of 60℃. Add 10mL of magnesium oxide emulsion every 10min until the pH of the solution is 7.2. Stop stirring for 3 hours and achieve solid-liquid separation by vacuum filtration. Wash the filter residue three times with clean water to obtain the uranium-removed cobalt hydroxide product.

[0041] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 2.

[0042] Table 2. Analytical results of uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products from Example 1. Example 1 shows that the crude cobalt hydroxide intermediate product enriched in the raw material can be processed to obtain high-quality crude cobalt hydroxide (cobalt hydroxide product with uranium removal) with a grade of 47.03%, a uranium content as low as 13 ppm, a cumulative uranium removal rate of 97.57%, a uranium removal slag rate of 8.1%, and a cobalt loss rate of 0.87% during the uranium removal process.

[0043] Comparative Example 1 This comparative example uses the same raw materials as Example 1 and prepares the same cobalt-containing solution; the difference from Example 1 is that the reagents used for tandem uranium removal of the cobalt-containing solution are changed to quicklime and phosphoric acid; the specific operation is as follows: At a temperature of 40℃, 10wt% lime slurry was slowly added to the cobalt-containing solution until the pH of the solution was 5.5. Phosphoric acid solution was added dropwise until the pH of the solution was 5.25. The mixture was stirred for 30 minutes to ensure a complete reaction, and the uranium-removed solution was obtained. The obtained uranium-removed feed solution was treated in the same way as in Example 1 to obtain uranium-rich filter residue and uranium-removed cobalt solution; the uranium-removed cobalt solution was treated in the same way as in Example 1 to obtain uranium-removed cobalt hydroxide product.

[0044] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 3.

[0045] Table 3. Analytical results of uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products from Comparative Example 1. Comparative Example 1 uses existing separation methods to separate crude cobalt hydroxide from uranium and impurities, and can obtain crude cobalt hydroxide (uranium-removed cobalt hydroxide product) with a grade of 33.68%, a uranium content of 50.70 ppm, a cumulative uranium removal rate of 90.51%, a uranium removal slag rate of 125.0%, and a cobalt loss rate of 4.63% during the uranium removal process.

[0046] Compared with Comparative Example 1, Example 1 showed that the cobalt grade of the uranium-free cobalt hydroxide product was increased by 13.35 wt%, the uranium content of the product was reduced by 37.7 ppm, the slag rate was reduced by more than 93%, and the cobalt loss rate was reduced by more than 80%.

[0047] Example 2 In this embodiment, the uranium-rich cobalt hydroxide raw material is a crude cobalt hydroxide (Co(OH)2) intermediate product enriched with uranium from the raw material in the Democratic Republic of Congo. The chemical analysis results are shown in Table 4.

[0048] Table 4. Multi-element analysis results of crude cobalt hydroxide intermediate product in Example 2 The uranium removal method for uranium-rich cobalt hydroxide in this embodiment is as follows: (1) At a temperature of 41℃, weigh 10g of uranium-rich cobalt hydroxide raw material, add 510mL of 16g / L sulfuric acid solution to dissolve the crude cobalt hydroxide (the mass ratio of sulfuric acid solution to uranium-rich cobalt hydroxide raw material is about 51:1), stir thoroughly for 1 hour to ensure complete dissolution, and obtain a cobalt-containing solution with a pH value of 1.6. (2) At a temperature of 41°C, add 21wt% ammonia solution dropwise to the cobalt-containing solution and stir thoroughly to prevent local over-alkaliness until the pH of the solution is 3.85. (3) At a temperature of 41°C, slowly add 6 wt% hexamethylenetetramine solution to the liquid until the pH of the liquid is 5.60. (4) At a temperature of 41°C, add 0.9 wt% phosphoric acid solution dropwise to the solution until the pH of the solution is 5.30. Stir for 30 minutes to ensure the reaction is complete and obtain the uranium removal solution. (5) The uranium-removing liquid is filtered to achieve solid-liquid separation. The filter residue is washed twice with clean water. The washing liquid is combined with the filtrate to obtain uranium-rich filter residue and uranium-removing cobalt solution. (6) Add 11 wt% magnesium oxide emulsion to the uranium-removed cobalt solution to precipitate cobalt at a temperature of 61°C. Add 10 mL of magnesium oxide emulsion every 10 min until the pH of the solution reaches 7.21. Stop stirring for 3 hours and achieve solid-liquid separation by filtration. Wash the filter residue three times with clean water to obtain the uranium-removed cobalt hydroxide product.

[0049] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 5.

[0050] Table 5. Analysis results of uranium-rich filter residue, uranium-cobalt removal solution, and uranium-cobalt hydroxide products from Example 2. Example 2 processed the uranium-enriched crude cobalt hydroxide intermediate product from the raw material to obtain high-quality crude cobalt hydroxide (uranium-removed cobalt hydroxide product) with a grade of 46.40%, a uranium content as low as 15 ppm, a cumulative uranium removal rate of 97.27%, a uranium slag removal rate of 8.5%, and a cobalt loss rate of 0.84% ​​during the uranium removal process.

[0051] Comparative Example 2 This comparative example uses the same raw materials as Example 2 and prepares the same cobalt-containing solution; the difference from Example 2 is that the reagents used for tandem uranium removal of the cobalt-containing solution are changed to quicklime and phosphoric acid; the specific operation is as follows: At a temperature of 41℃, 10wt% lime slurry was slowly added to the cobalt-containing solution until the pH of the solution was 5.60. Phosphoric acid solution was added dropwise until the pH of the solution was 5.30. The mixture was stirred for 30 minutes to ensure a complete reaction, and the uranium-removed solution was obtained. The obtained uranium-removed feed solution was treated in the same way as in Example 2 to obtain uranium-rich filter residue and uranium-removed cobalt solution; the uranium-removed cobalt solution was treated in the same way as in Example 2 to obtain uranium-removed cobalt hydroxide product.

[0052] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 6.

[0053] Table 6. Analytical results of uranium-rich filter residue, uranium-cobalt removal solution, and uranium-cobalt hydroxide product from Comparative Example 2. Comparative Example 2 uses existing separation methods to separate crude cobalt hydroxide from uranium and impurities, and can obtain crude cobalt hydroxide (uranium-removed cobalt hydroxide product) with a grade of 35.46%, a uranium content of 52.00 ppm, a cumulative uranium removal rate of 90.55%, a uranium removal slag rate of 115.8%, and a cobalt loss rate of 4.35% during the uranium removal process.

[0054] Compared with Comparative Example 2, Example 2 showed that the cobalt grade of the uranium-free cobalt hydroxide product was increased by 10.94 wt%, the uranium content of the product was reduced by 37.00 ppm, the slag rate was reduced by more than 92%, and the cobalt loss rate was reduced by more than 80%.

[0055] Example 3 In this embodiment, the uranium-rich cobalt hydroxide raw material comes from a crude cobalt hydroxide (Co(OH)2) intermediate product enriched with uranium in the raw material in the Democratic Republic of Congo. The chemical analysis results are shown in Table 7.

[0056] Table 7. Multi-element analysis results of crude cobalt hydroxide intermediate product in Example 3 The uranium removal method for uranium-rich cobalt hydroxide in this embodiment is as follows: (1) At a temperature of 39℃, weigh 10g of uranium-rich cobalt hydroxide raw material, add 490mL of 14g / L sulfuric acid solution to dissolve the crude cobalt hydroxide (the mass ratio of sulfuric acid solution to uranium-rich cobalt hydroxide raw material is about 49:1), stir thoroughly for 1 hour to ensure complete dissolution, and obtain a cobalt-containing solution with a pH value of 1.65. (2) At a temperature of 39°C, add 19wt% ammonia solution dropwise to the cobalt-containing solution and stir thoroughly to prevent local over-alkaliness until the pH of the solution is 3.9. (3) At a temperature of 39°C, slowly add 4 wt% hexamethylenetetramine solution to the liquid until the pH of the liquid is 5.55; (4) At a temperature of 39°C, add 1.1 wt% phosphoric acid solution dropwise to the solution until the pH of the solution is 5.28. Stir for 30 minutes to ensure the reaction is complete and obtain the uranium removal solution. (5) The uranium-removing liquid is filtered to achieve solid-liquid separation. The filter residue is washed twice with clean water. The washing liquid is combined with the filtrate to obtain uranium-rich filter residue and uranium-removing cobalt solution. (6) Add 12wt% magnesium oxide emulsion to the uranium-removed cobalt solution to precipitate cobalt at a temperature of 58℃. Add 10mL of magnesium oxide emulsion every 10min until the pH of the solution is 7.21. Stop stirring for 3 hours and achieve solid-liquid separation by filtration. Wash the filter residue three times with clean water to obtain the uranium-removed cobalt hydroxide product.

[0057] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 8.

[0058] Table 8. Analytical results of uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products from Example 3. Example 3 processed the uranium-enriched crude cobalt hydroxide intermediate product from the raw material to obtain high-quality crude cobalt hydroxide (uranium-removed cobalt hydroxide product) with a grade of 46.18%, a uranium content as low as 10 ppm, a cumulative uranium removal rate of 98.15%, a uranium slag removal rate of 8.6%, and a cobalt loss rate of 0.87% during the uranium removal process.

[0059] Comparative Example 3 This comparative example uses the same raw materials as Example 3 and prepares the same cobalt-containing solution; the difference from Example 3 is that the reagents used for tandem uranium removal of the cobalt-containing solution are changed to quicklime and phosphoric acid; the specific operation is as follows: At a temperature of 40℃, 10wt% lime slurry was slowly added to the cobalt-containing solution until the pH of the solution was 5.55. Phosphoric acid solution was added dropwise until the pH of the solution was 5.28. The mixture was stirred for 30 minutes to ensure a complete reaction, and the uranium-removed solution was obtained. The obtained uranium-removed feed solution was treated in the same way as in Example 3 to obtain uranium-rich filter residue and uranium-removed cobalt solution; the uranium-removed cobalt solution was treated in the same way as in Example 3 to obtain uranium-removed cobalt hydroxide product.

[0060] The testing results for uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide products are shown in Table 9.

[0061] Table 9. Analytical results of uranium-rich filter residue, uranium-removed cobalt solution, and uranium-removed cobalt hydroxide product from Comparative Example 3. Comparative Example 2 uses existing separation methods to separate crude cobalt hydroxide from uranium and impurities, and can obtain crude cobalt hydroxide (uranium-removed cobalt hydroxide product) with a grade of 34.98%, a uranium content of 49.00 ppm, a cumulative uranium removal rate of 90.93%, a uranium slag removal rate of 123.2%, and a cobalt loss rate of 4.36% during the uranium removal process.

[0062] Compared with Comparative Example 3, Example 3 showed that the cobalt grade of the uranium-free cobalt hydroxide product was increased by 11.20 wt%, the uranium content of the product was reduced by 39.00 ppm, the slag rate was reduced by more than 93%, and the cobalt loss rate was reduced by more than 80%.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for uranium removal from uranium-rich cobalt hydroxide, characterized in that, Uranium-rich cobalt hydroxide raw material is mixed with acid to prepare a cobalt-containing solution with a pH value of 1.0~1.7; the cobalt-containing solution is subjected to uranium removal in series to obtain a uranium-removed solution; the uranium-removed solution is separated into solid and liquid components to obtain uranium-rich filter residue and uranium-removed cobalt solution. The tandem uranium removal method involves: adding an ammonia solution to the cobalt-containing feed solution until the pH value is 3.8-3.9; then adding a hexamethylenetetramine solution until the pH value is 5.4-5.6; and finally adding a phosphoric acid solution until the pH value is 5.2-5.3 to obtain the uranium-removed feed solution.

2. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1, characterized in that, The cobalt-containing liquid contains uranium at a concentration of 10 ppm to 15 ppm.

3. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The temperature of the tandem uranium removal process is 39℃~41℃.

4. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The mass ratio of crude cobalt hydroxide raw material to acid solution is 1:48~52.

5. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The acid solution is a sulfuric acid solution with a concentration of 14 g / L to 16 g / L.

6. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The concentration of the ammonia solution is 19wt%~21wt%.

7. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The concentration of the hexamethylenetetramine solution is 4wt%~6wt%.

8. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, The concentration of the phosphoric acid solution is 0.8wt%~1.2wt%.

9. The method for uranium removal from uranium-rich cobalt hydroxide according to claim 1 or 2, characterized in that, Magnesium oxide is added to the uranium-removed cobalt solution to precipitate cobalt until the pH value reaches 7.18~7.

22. Solid-liquid separation is then performed to obtain the uranium-removed cobalt hydroxide product.

10. The method for removing uranium from uranium-rich cobalt hydroxide according to claim 9, characterized in that, The temperature for cobalt deposition is 58℃~62℃.

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