Method for removing silicon, uranium, iron and aluminum impurities in acid leaching solution of rare earth acid dissolution residue alkaline roasting residue

Abstract

The present application relates to a kind of rare earth acid dissolution residue base roasting residue acid leaching liquid silicon uranium iron aluminum impurity removal method.The removal method includes: first, adjust the temperature of rare earth acid dissolution residue base roasting residue acid leaching liquid to target temperature, then adjust the pH of rare earth acid dissolution residue base roasting residue acid leaching liquid to target pH, carry out hydrolysis reaction;Hydrolysis reaction is finished, and aging is carried out, solid-liquid separation is obtained, and the removal purification liquid is removed with silicon uranium iron aluminum impurity residue;The target temperature is 60~95 ℃, and the target pH is 3.2~4.7.The present application controls the temperature and pH of rare earth acid dissolution residue base roasting residue acid leaching liquid, etc., strengthens the common hydrolysis process of silicon iron aluminum, controls the morphology structure of silicon iron aluminum mixed hydrolysis product, makes it have strong adsorption capacity to uranium nuclide, realizes the in-situ synchronous removal of silicon uranium iron aluminum impurity in rare earth acid dissolution residue base roasting residue acid leaching liquid, provides a new way for the purification treatment of rare earth acid dissolution residue base roasting residue acid leaching liquid.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to the resource utilization of acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue, and particularly to a method for removing silicon, uranium, iron and aluminum impurities from acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. Background Technology

[0002] Rare earth elements are a critical metal resource. The production of ion-adsorption rare earth ores generates large quantities of low-radioactive rare earth acid-soluble slag. The main components include BaSO4, SiO2, Fe2O3, Al2O3, rare earth elements, and radioactive nuclides such as thorium, uranium, and radium. After drying, the acid-soluble slag typically contains 30%–60% BaSO4, 10%–20% SiO2, 10%–15% Al2O3, less than 4% Fe2O3, and at least 1% rare earth elements (calculated as rare earth oxides). Among the trace radioactive nuclides, uranium mononuclides have a specific activity of ~20 Bq / g, classifying them as low-level radioactive waste.

[0003] After rare earth acid-soluble residue is roasted in an alkaline medium, BaSO4 is converted into acid-soluble barium salts. The main components of the leaching solution obtained by hydrochloric acid leaching include barium, rare earth elements, silicon, iron, aluminum, and trace amounts of uranium. High concentrations of silicon readily hydrolyze in the acidic solution, forming silica sol, which severely affects the flowability and filtration of the solution, and may even form silica gel, further disrupting stable production. Iron and aluminum impurities increase the extraction and separation costs of rare earths, while small amounts of uranium nuclides lead to radioactive contamination of the entire production line and rare earth products. Therefore, to achieve the resource utilization of the leaching solution from the alkaline roasting residue of rare earth acid-soluble residue, it is necessary to remove silicon, uranium, iron, and aluminum impurities from the leaching solution.

[0004] CN103184343A discloses a method for recovering rare earth elements, thorium, and iron from waste residue in a rare earth acid process. The method includes mixing the waste residue with a mixed acid solution of HCl, H₂SO₄, or HNO₃ at an acid-to-slag ratio of 0.2:1 to 1.0:1, stirring and leaching at temperatures from 60°C to boiling, yielding a leachate and secondary waste residue. The leachate is then extracted with a primary amine and back-extracted with nitric acid to obtain a thorium nitrate solution. The remaining thorium extraction liquid is adjusted to pH 4.5-5.5 with alkali to precipitate Fe(OH)₃ as a byproduct. The filtrate is a rare earth feed product. This technical solution is cumbersome, consumes a large amount of acid, and has poor environmental performance.

[0005] CN119392013A discloses a method for rare earth recovery from ionic rare earth acid-dissolving slag. The method involves adding water to the ionic rare earth concentrate acid-dissolving slag to form a slurry. First, sodium hydroxide solution is added for alkali conversion to remove fluoride. Simultaneously, some aluminum and silicon impurities are converted into soluble acid radicals and removed through filtration and washing. Rare earth elements, along with calcium, thorium, and iron in the slag, remain as hydroxides in the solid precipitate, forming an alkali cake. The alkali cake slurry is then acid-dissolved, during which rare earth elements and impurities such as calcium, thorium, and iron are dissolved, yielding a crude rare earth solution. Oxalic acid solution is added to the crude rare earth solution to precipitate a poorly soluble oxalic acid-rare earth mixture. Finally, the mixture is calcined at high temperature to obtain mixed rare earth oxides. This technical solution also requires a large amount of acid to react under heating conditions, generating acidic gases, and the post-processing is complex. Furthermore, this technical solution does not address the recovery of radioactive elements.

[0006] CN106367621A discloses a method for recovering and recycling valuable elements from low-concentration rare earth solutions and precipitates. The method includes neutralizing a solution containing low-concentration rare earths with alkali to precipitate rare earth and high-valence metal ions such as aluminum; leaching rare earth, aluminum, uranium, and thorium metals with sulfuric acid to obtain a leachate; successively extracting uranium from the leachate with an organic phase containing tertiary amine extractants such as N235, and extracting rare earths and thorium with an organic phase containing primary amine extractants such as N1923; back-extracting uranium from the organic phase with nitric acid solution, and back-extracting rare earths and thorium from the organic phase with hydrochloric acid and its salts, and nitric acid and its salts solutions; and recovering the back-extracted rare earth and thorium solutions by precipitation. This technical solution not only involves the use of large amounts of acid but also involves multiple extraction and back-extraction processes, making the process flow complex.

[0007] Existing technologies for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residues and alkaline roasting residues all require complex and lengthy processes and rely on the use of large amounts of acid, extractants, or adsorbents, resulting in high costs. Therefore, there is an urgent need to develop a simple method for the in-situ simultaneous removal of silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residues and alkaline roasting residues. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. This invention enhances the co-hydrolysis process of silicon, iron, and aluminum by controlling the temperature and pH of the acid leaching solution, thereby regulating the morphology and structure of the mixed hydrolysis products to enhance their adsorption capacity for uranium nuclides. This achieves in-situ simultaneous removal of silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. Furthermore, the removal method provided by this invention boasts a high removal rate and a simple process, offering a new approach for the purification and treatment of acid leaching solutions of rare earth acid-soluble residue and alkaline roasting residue.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The elements in the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue include at least barium, rare earth elements, silicon, aluminum, iron, and uranium. The removal method includes: first adjusting the temperature of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to a target temperature, then adjusting the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to a target pH, and carrying out a hydrolysis reaction; after the hydrolysis reaction is completed, aging is carried out, and solid-liquid separation is performed to obtain a purified solution and silicon, uranium, iron, and aluminum impurity residue; the target temperature is 60℃~95℃, and the target pH is 3.2~4.7.

[0011] In this invention, by controlling the temperature and pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue, the co-hydrolysis process of silicon, iron, and aluminum is enhanced at the target temperature and pH, rapidly forming a hydrolysis mixture in situ. Furthermore, the formed hydrolysis mixture exhibits a strong adsorption capacity for uranium nuclides, achieving simultaneous uranium removal through aging. This invention achieves simultaneous in-situ removal of silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue without introducing additional acids, adsorbents, or extractants. It also boasts a high removal rate, a simple process, and overcomes the problems of instability in the acid leaching solution and poor filtration performance caused by high silicon content, providing a new approach for the purification and treatment of acid leaching solutions of rare earth acid-soluble residue and alkaline roasting residue.

[0012] Preferably, the method for adjusting the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to the target pH includes: using a first alkaline solution to adjust the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to a difference of 0.4 to 0.6 from the target pH, and then using a second alkaline solution to adjust the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to the target pH; the concentration of the first alkaline solution is greater than the concentration of the second alkaline solution.

[0013] Preferably, the first alkaline solution and the second alkaline solution each independently comprise any one or a combination of at least two of NaOH solution, KOH solution, ammonia water, or Ca(OH)2 slurry.

[0014] Preferably, when the first alkaline solution includes NaOH solution, KOH solution or ammonia solution, the concentration of the first alkaline solution is 1 mol / L to 15 mol / L.

[0015] Preferably, when the first alkaline solution includes Ca(OH)2 slurry, the concentration of the first alkaline solution is 1wt%~10wt%.

[0016] Preferably, the concentration of the second alkaline solution is less than 1 mol / L, and more preferably 0.05 mol / L to 0.5 mol / L.

[0017] Preferably, the hydrolysis reaction takes 3 to 180 minutes.

[0018] Preferably, the hydrolysis reaction takes 3 to 20 minutes.

[0019] Preferably, the hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 5000 rpm.

[0020] Preferably, the hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 2000 rpm.

[0021] Preferably, the aging temperature is 30℃~90℃.

[0022] Preferably, the aging temperature is 40℃~80℃.

[0023] Preferably, the aging time is 0h to 48h.

[0024] Preferably, the aging time is 6h to 12h.

[0025] Preferably, the aging process further includes stirring, and the stirring rate is 50 rpm to 300 rpm.

[0026] Preferably, the initial pH value of the acid leaching solution of the rare earth acid-soluble residue and alkaline roasting residue is <1, and the initial silicon concentration is 1%. <c Si <40 g / L, with an initial uranium concentration of ≤1 g / L.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The removal method provided by the present invention achieves in-situ simultaneous removal of silicon, uranium, iron and aluminum impurities in rare earth acid soluble residue alkaline roasting residue acid leaching solution by adjusting the temperature and pH of the acid leaching solution of rare earth acid soluble residue alkaline roasting residue through hydrolysis reaction and aging. The removal rate is high and the process is simple, providing a new way for the purification treatment of rare earth acid soluble residue alkaline roasting residue acid leaching solution.

[0029] (2) The removal method provided by the present invention does not require the introduction of additional acid, adsorbent and extractant. The process is simple, the removal rate is high, and it also overcomes the problems of unstable acid leaching solution and poor system filtration performance caused by high silica.

[0030] (3) The removal method provided by the present invention can achieve a silicon removal rate of 99.37%, a uranium removal rate of 99.68%, an iron removal rate of 99.54%, an aluminum removal rate of 99.29%, a barium loss rate of 3.05%, and a rare earth loss rate as low as 5.56% in the acid leaching solution of rare earth acid dissolution residue and alkaline roasting residue. Attached Figure Description

[0031] Figure 1 This is a SEM image of the silicon-uranium-iron-aluminum impurity slag obtained in Example 1.

[0032] Figure 2 This is the EDS spectrum of silicon in the silicon-uranium-iron-aluminum impurity slag obtained in Example 1.

[0033] Figure 3 This is the EDS spectrum of aluminum in the silicon-uranium-iron-aluminum impurity slag obtained in Example 1.

[0034] Figure 4 This is the EDS spectrum of iron in the silicon-uranium-iron-aluminum impurity slag obtained in Example 1.

[0035] Figure 5 This is the EDS spectrum of uranium in the silicon-uranium-iron-aluminum impurity slag obtained in Example 1.

[0036] Figure 6 This is the EDS spectrum of barium in the silicon-uranium-iron-aluminum impurity slag obtained in Example 1. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0038] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0039] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0040] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0041] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0042] In one specific embodiment, the present invention provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The elements in the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue include at least barium, rare earth elements, silicon, aluminum, iron, and uranium. The removal method includes: first adjusting the temperature of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to a target temperature, then adjusting the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to a target pH, and carrying out a hydrolysis reaction; after the hydrolysis reaction is completed, aging is carried out, and solid-liquid separation is performed to obtain a purified solution and silicon, uranium, iron, and aluminum impurity residue; the target temperature is 60℃~95℃, and the target pH is 3.2~4.7.

[0043] In this invention, by controlling the temperature and pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue, the co-hydrolysis process of ferrosilicon and aluminum is enhanced at target temperatures and pH values, rapidly forming hydrolyzed mixed products in situ. In this invention, the target temperature can be, for example, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 95℃, and the target pH can be, for example, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, or 4.7. At these target temperatures and pH values, the maximum hydrolysis of ferrosilicon and aluminum can be achieved. Furthermore, the presence of iron and aluminum hydrolysis products significantly inhibits the gelation of silicon hydrolysis, overcoming the problem of poor filtration performance and interference with smooth production caused by excessive sol-gelation during silicon removal.

[0044] Furthermore, at the target temperature and pH, the hydrolysis mixture formed by silicon, iron, and aluminum exhibits a strong adsorption capacity for uranium nuclides, and through aging, simultaneous removal of uranium is achieved.

[0045] Therefore, this invention achieves in-situ simultaneous removal of silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution without the need to introduce additional acids, adsorbents, and extractants. It also achieves high removal rates, simple processes, and overcomes the problems of instability of the leaching solution and poor filtration performance caused by high silicon content. This provides a new approach for the purification and treatment of rare earth acid-soluble residue and alkaline roasting residue leaching solution.

[0046] In some embodiments, the method of adjusting the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to a target pH includes: using a first alkaline solution to adjust the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to a difference of 0.4 to 0.6 from the target pH, for example, 0.4, 0.45, 0.5, 0.55, or 0.6, and then using a second alkaline solution to adjust the pH of the rare earth acid-soluble residue alkaline roasting residue leaching solution to the target pH; the concentration of the first alkaline solution is greater than the concentration of the second alkaline solution.

[0047] In some embodiments, the first alkaline solution and the second alkaline solution each independently comprise any one or a combination of at least two of NaOH solution, KOH solution, ammonia water, or Ca(OH)2 slurry.

[0048] In some embodiments, when the first alkaline solution includes NaOH solution, KOH solution, or ammonia solution, the concentration of the first alkaline solution is 1 mol / L to 15 mol / L, for example, it can be 1 mol / L, 3 mol / L, 5 mol / L, 7 mol / L, 9 mol / L, 11 mol / L, 13 mol / L, or 15 mol / L; when the first alkaline solution includes Ca(OH)2 slurry, the concentration of the first alkaline solution is 1 wt% to 10 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, or 10 wt%.

[0049] In some embodiments, the concentration of the second alkaline solution is less than 1 mol / L, for example, it can be 0.02 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L or 0.9 mol / L, preferably 0.05 mol / L to 0.5 mol / L.

[0050] In some embodiments, the hydrolysis reaction time is 3 min to 180 min, for example, it can be 3 min, 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min or 180 min.

[0051] In some embodiments, the hydrolysis reaction time is 3 min to 20 min, for example, it can be 3 min, 5 min, 7 min, 9 min, 10 min, 12 min, 14 min, 16 min, 18 min or 20 min.

[0052] In some embodiments, the hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 5000 rpm, for example, 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm or 5000 rpm.

[0053] In some embodiments, the hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 2000 rpm, for example, 500 rpm, 700 rpm, 900 rpm, 1000 rpm, 1200 rpm, 1400 rpm, 1600 rpm, 1800 rpm or 2000 rpm.

[0054] In some embodiments, the aging temperature is 30°C to 90°C, for example, it can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 90°C.

[0055] In some embodiments, the aging temperature is 40°C to 80°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0056] In some embodiments, the aging time is 0h to 48h, for example, it can be 0h, 4h, 8h, 12h, 16h, 20h, 24h, 28h, 32h, 36h, 40h, 44h or 48h.

[0057] In some implementations, the aging time is 6h to 12h, for example, 6h, 7h, 8h, 9h, 10h, 11h or 12h.

[0058] In some embodiments, the aging process further includes stirring at a rate of 50 rpm to 300 rpm, for example, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, or 300 rpm. In this invention, aging can be carried out by standing still or by slow stirring.

[0059] In some embodiments, the initial pH value of the rare earth acid-soluble residue alkaline roasting residue leaching solution is <1, for example, it can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, and the initial silicon concentration is 1%. <c Si <40 g / L, for example, it can be 1.05 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 30 g / L or 40 g / L, and the initial uranium concentration is ≤1 g / L, for example, it can be 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L or 1.0 g / L.

[0060] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0061] Example 1

[0062] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The acid leaching solution of the rare earth acid-soluble residue and alkaline roasting residue contains H... + The concentration was 0.32 mol / L, and the main components included barium, rare earth elements, iron and aluminum chloride salts, silicates and radioactive nuclides such as uranium. The contents obtained by inductively coupled plasma atomic emission spectrometry (ICP-OES, PQ9000) are shown in Table 1.

[0063] Table 1

[0064]

[0065] The removal method includes:

[0066] The acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue was heated to 90℃ and stirred at 2000 rpm. The pH of the acid leaching solution was adjusted to 3.4 using 12 mol / L NaOH solution. Then, it was titrated with 0.1 mol / L NaOH solution until the pH reached 3.9. The hydrolysis reaction was carried out for 20 min while stirring at 2000 rpm. After the hydrolysis reaction was completed, the solution was aged for 0 h. The solid and liquid were separated to obtain the purified solution and silicon, uranium, iron and aluminum impurity residue.

[0067] The SEM image of the silicon-uranium-iron-aluminum impurity slag obtained in this embodiment is as follows: Figure 1 As shown, the EDS spectra of silicon, aluminum, iron, uranium, and barium in the silicon-uranium-iron-aluminum impurity slag are respectively as follows: Figures 2 to 6 As shown.

[0068] The composition of the silicon-uranium-iron-aluminum impurity slag obtained in this embodiment was tested by XRF method, and the test results are shown in Table 2.

[0069] Table 2

[0070]

[0071] Table 2 shows that the main components of the silicon-uranium-iron-aluminum impurity slag include 65.43 wt% SiO2, 20.41 wt% Al2O3, 8.08 wt% Fe2O3, and enriched uranium with a U3O8 content of 0.05 wt%. It also contains small amounts of BaO and REO, at 1.49 wt% and 1.89 wt%, respectively. Figures 1-6It can be seen that the distribution of silicon is positively correlated with that of iron and aluminum, indicating that silicic acid in the hydrolysis mixture is positively correlated with iron hydroxide and aluminum hydroxide.

[0072] Example 2

[0073] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0074] The removal method is the same as in Example 1, except that the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is first adjusted to 2.6 using 12 mol / L NaOH solution, and then titrated to 3.2 using 0.1 mol / L NaOH solution.

[0075] Example 3

[0076] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0077] The removal method is the same as in Example 1, except that the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is first adjusted to 4.3 using 12 mol / L NaOH solution, and then titrated to 4.7 using 0.1 mol / L NaOH solution.

[0078] Example 4

[0079] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0080] The removal method is the same as in Example 1, except that the rare earth acid-soluble residue alkali roasting residue acid leaching solution is heated to 70°C.

[0081] Example 5

[0082] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0083] The removal method is the same as in Example 1, except that the rare earth acid-soluble residue alkali roasting residue acid leaching solution is heated to 60°C.

[0084] Example 6

[0085] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0086] The removal method is the same as in Example 1, except that the hydrolysis reaction time is 3 minutes.

[0087] Example 7

[0088] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0089] The removal method is the same as in Example 1, except that the hydrolysis reaction time is 180 min.

[0090] Example 8

[0091] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0092] The removal method is the same as in Example 1, except that the rotation speed during the hydrolysis reaction is 500 rpm.

[0093] Example 9

[0094] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0095] The removal method is the same as in Example 1, except that the rotation speed during the hydrolysis reaction is 5000 rpm.

[0096] Example 10

[0097] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0098] The removal method is the same as in Example 1, except that 12 mol / L KOH solution is used to replace 12 mol / L NaOH solution, the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is adjusted to 3.4, and then 0.1 mol / L KOH solution is used to replace 0.1 mol / L NaOH solution to continue titrating to pH 3.9.

[0099] Example 11

[0100] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0101] The removal method is the same as in Example 1, except that 10 wt% Ca(OH)2 slurry is used to replace 12 mol / L NaOH solution, the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is adjusted to 3.4, and then 0.1 mol / L Ca(OH)2 slurry is used to replace 0.1 mol / L NaOH solution to continue titrating to pH 3.9.

[0102] Example 12

[0103] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0104] The removal method is the same as in Example 1, except that a 12 mol / L ammonia solution is used to replace the 12 mol / L NaOH solution, the pH of the rare earth acid-soluble residue alkaline roasting residue acid leaching solution is adjusted to 3.4, and then a 0.8 mol / L ammonia solution is used to replace the 0.1 mol / L NaOH solution to continue titrating until the pH is 3.9.

[0105] Example 13

[0106] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0107] The removal method is the same as in Example 1, except that a 2.5 mol / L NaOH solution is used to replace the 12 mol / L NaOH solution, the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is adjusted to 3.4, and then titrated with a 0.1 mol / L NaOH solution until the pH is 3.9.

[0108] Example 14

[0109] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0110] The removal method is the same as in Example 1, except that after hydrolysis, the material is left to stand and age for 1 hour.

[0111] Example 15

[0112] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0113] The removal method is the same as in Example 1, except that after hydrolysis, the material is left to stand and age for 48 hours.

[0114] Example 16

[0115] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0116] The removal method is the same as in Example 1, except that after hydrolysis, the sample is aged at 300 rpm for 12 hours.

[0117] Example 17

[0118] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. Except that the uranium content in the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is 1.0 g / L, the rest is the same as in Example 1.

[0119] Example 18

[0120] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0121] The removal method is the same as in Example 1, except that the hydrolysis reaction time is 1 minute.

[0122] Example 19

[0123] This embodiment provides a method for removing silicon, uranium, iron, and aluminum impurities from rare earth acid-soluble residue and alkaline roasting residue leaching solution. The rare earth acid-soluble residue and alkaline roasting residue leaching solution used in this embodiment is the same as that in Example 1.

[0124] The removal method is the same as in Example 1, except that the pH of the acid leaching solution of the rare earth acid-soluble residue and alkaline roasting residue is directly adjusted to 3.9 using a 12 mol / L NaOH solution.

[0125] Comparative Example 1

[0126] This comparative example provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue used in this comparative example is the same as that in Example 1.

[0127] The extraction method is the same as in Example 1, except that the hydrolysis temperature is 50°C.

[0128] Comparative Example 2

[0129] This comparative example provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue used in this comparative example is the same as that in Example 1.

[0130] The extraction method is the same as in Example 1, except that the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is adjusted to 1.4 using 12 mol / L NaOH solution, and then titrated to 1.8 using 0.1 mol / L NaOH solution.

[0131] Comparative Example 3

[0132] This comparative example provides a method for removing silicon, uranium, iron, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue. The acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue used in this comparative example is the same as that in Example 1.

[0133] The extraction method is the same as in Example 1, except that the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is adjusted to 4.5 with 12 mol / L NaOH solution, and then titrated to pH 5.0 with 0.1 mol / L NaOH solution.

[0134] Performance testing:

[0135] The filtration rates of the removal methods provided in all the above embodiments and comparative examples during the solid-liquid separation process were tested, and the test results are shown in Table 3.

[0136] The concentrations of each element in the purified solutions obtained in all the above examples and comparative examples were measured using an inductively coupled plasma optical emission spectrometer (ICP-OES, PQ9000), and the removal rate of each element was calculated. The removal rate of each element was calculated by formula (I).

[0137] (I)

[0138] In formula (I), c0 represents the concentration of each element before treatment, in g / L; V0 represents the volume of the liquid before treatment, in m³. 3 c1 represents the concentration of each element after treatment, in g / L; V1 represents the volume of the treated liquid, in m³. 3 .

[0139] The test results are shown in Table 3.

[0140] Table 3

[0141]

[0142] In summary, this invention enhances the co-hydrolysis process of silicon, ferro, and aluminum by controlling the temperature and pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue, and regulates the structure and morphology of the mixed hydrolysis products, giving them a strong adsorption capacity for uranium nuclides. Without the need for additional adsorbents or extractants, the in-situ simultaneous removal of silicon, uranium, ferro, and aluminum impurities from the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue is achieved.

[0143] According to Examples 1 to 19 in Table 3, the removal method provided by the present invention can achieve a silicon removal rate of over 99.69%, a uranium removal rate of 99.97%, an iron removal rate of 99.88%, and an aluminum removal rate of 99.88% in the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue, with a barium loss rate as low as 1.06% and a rare earth loss rate as low as 1.81%; the filtration rate is as high as 486.73 mL / (m 2 This overcomes the problem of poor filtration performance caused by the formation of gels from high-concentration silica in conventional solid-liquid separation.

[0144] Comparing Examples 1 to 3 and Comparative Examples 2 to 3 in Table 3, it can be seen that within the experimental range, when pH=1.8, the solution pH is low and cannot effectively promote silicon hydrolysis. Only 33.06% of silicon precipitates as hydrolysis products, while the remainder exists in the form of silica sol, resulting in a significant decrease in filtration rate (60.63 mL / (m²·s)). Although the loss rates of rare earth elements and barium are low at this time (1.72% and 1.06%, respectively), the removal rates of uranium, iron, and aluminum also decrease significantly (6.47%, 6.32%, and 3.55%, respectively). As pH increases, the removal rates of silicon, uranium, iron, and aluminum all increase rapidly at first and then tend to stabilize. This is because when the pH is raised above 3.2, silica sol and silicon ions are converted into silicon hydrolysis products and removed, resulting in a significant increase in filtration speed. However, when the pH is excessively raised to 5, the loss rates of rare earth elements and barium increase rapidly, and the filtration speed decreases slightly to 182.21 mL / (m²·s). Therefore, a suitable pH range is beneficial for achieving high removal rates of silicon, uranium, iron, and aluminum, high filtration speed, while reducing the loss rates of rare earth elements and barium.

[0145] Comparing Examples 1, 4, and 5 in Table 3 with Comparative Example 1, it can be seen that as the temperature increases, the supersaturation increases, which accelerates nucleation and promotes the precipitation of hydrolysis products with a denser and more crystalline morphology. Therefore, the removal rates of silicon, uranium, iron, and aluminum increase, the filtration speed improves, and the filtration performance is improved. However, the loss rates of rare earth elements and barium increase slightly. Therefore, setting the temperature within a reasonable range is beneficial to improving the removal rates of silicon, uranium, iron, and aluminum and improving the filtration performance, while controlling the loss rates of rare earth elements and barium within a certain range.

[0146] Comparing Examples 1, 6 to 7 and Example 18 in Table 3, it can be seen that when the hydrolysis time is extended to more than 3 minutes, silicon can be fully hydrolyzed and co-precipitated with iron and aluminum to form a mixed hydrolysis product with stable structure and good particle size. The adsorption sites tend to be saturated, uranium removal increases first and then stabilizes, rare earth and barium show slight loss but the increase is limited. At the same time, the precipitated particles are long and dense, the filter cake pore structure is improved, and the filtration speed is improved.

[0147] Comparing Examples 1 and 8-9 in Table 3, it can be seen that the stirring speed has little effect on the removal rate of silicon, uranium, iron, and aluminum, and the loss rate of rare earth and barium; however, the stirring speed has a significant impact on the filtration performance. Low speed easily forms loose and uneven agglomerates, resulting in medium filtration speed; medium speed forms uniform micron flocs, resulting in better filtration; and high speed results in finer hydrolysis product particles and poorer filtration performance.

[0148] Comparing Examples 1, 10, and 13 in Table 3, it can be seen that adjusting the pH with different alkaline solutions has no significant effect on the removal rate and loss rate. However, strong alkalis such as KOH and NaOH provide a high concentration of OH- instantly. - This results in fine, amorphous, gel-like crystallized products, slightly affecting filtration performance; while ammonia water and Ca(OH)2 slurry, due to OH... - Slow release and low local supersaturation promote particle growth and regular morphology, resulting in significantly better filtration performance. Reducing the NaOH concentration can weaken the local supersaturation effect and improve filtration performance.

[0149] Comparing Examples 1 and 14 to 16 in Table 3, it can be seen that short-term aging can mature and grow the hydrolysis product particles, resulting in a more complete structure and improved filtration performance, with the filtration rate increasing from 209.85 mL / (m²·s) to 267.53 mL / (m²·s). However, the particle specific surface area remains relatively large, increasing the adsorption sites and leading to a slight increase in barium and rare earth loss rates. The uranium removal rate decreases slightly, attributed to the back dissolution of trace amounts of uranium during aging. Further extending the aging time increases the crystallinity of the mixed hydrolysis products, reduces the specific surface area, and generates lattice repulsion, allowing adsorbed / co-precipitated / entrained rare earth and barium to return to the solution, which is beneficial for reducing barium and rare earth loss rates and further improving filtration performance. Aging under appropriate low-speed stirring is conducive to sufficient particle growth, regular morphology, high filter cake porosity, and fast filtration speed.

[0150] Comparing Examples 1, 17, and 19 in Table 3, it can be seen that the removal method provided by this invention is also applicable to systems with an initial uranium concentration as high as 1 g / L. However, adjusting the pH to the target level with a single addition of alkali solution leads to localized OH... - If the pH is too high momentarily, a small amount of fine colloids will be generated, which will slightly reduce the filtration performance; however, since the final pH is the same and the total amount of precipitate is similar, it has no significant effect on the removal rate of silicon, aluminum, and iron, or the loss rate of rare earth and barium.

[0151] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for removing silicon, uranium, iron and aluminum impurities in a leaching solution of a rare earth acid-soluble residue alkaline roasting residue, characterized in that, The elements in the acid leaching solution of the rare earth acid slag alkaline roasting residue include at least barium, rare earth elements, silicon, aluminum, iron and uranium; The removal method includes: First, adjust the temperature of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to the target temperature, then adjust the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to the target pH, and carry out the hydrolysis reaction; after the hydrolysis reaction is completed, age the solution and separate the solid and liquid to obtain the purified solution and silicon, uranium, iron and aluminum impurity residue. The target temperature is 70℃~95℃, and the target pH is 3.2~4.7; The hydrolysis reaction takes 3 min to 180 min; The initial pH value of the rare earth acid dissolved residue alkali roasting residue acid leaching solution is <1, and the initial silicon concentration is 1 Si <40 g / L, and the initial uranium concentration is ≤1 g / L.

2. The removal method as described in claim 1, characterized in that, The methods for adjusting the pH of the acid leaching solution of rare earth acid-soluble residue and alkaline roasting residue to the target pH include: The pH of the acid leaching solution of the rare earth acid soluble residue alkaline roasting residue is adjusted to a difference of 0.4 to 0.6 from the target pH using a first alkaline solution, and then the pH of the acid leaching solution of the rare earth acid soluble residue alkaline roasting residue is adjusted to the target pH using a second alkaline solution. The concentration of the first alkaline solution is greater than the concentration of the second alkaline solution.

3. The removal method as described in claim 2, characterized in that, The first alkaline solution and the second alkaline solution each independently comprise any one or a combination of at least two of NaOH solution, KOH solution, ammonia solution, or Ca(OH)2 slurry.

4. The removal method as described in claim 3, characterized in that, When the first alkaline solution is a NaOH solution, KOH solution, or ammonia solution, the concentration of the first alkaline solution is 1 mol / L to 15 mol / L.

5. The removal method as described in claim 3, characterized in that, When the first alkaline solution is Ca(OH)2 slurry, the concentration of the first alkaline solution is 1wt%~10wt%.

6. The removal method as described in claim 3, characterized in that, The concentration of the second alkaline solution is less than 1 mol / L.

7. The removal method as described in claim 1, characterized in that, The hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 5000 rpm.

8. The removal method as described in claim 7, characterized in that, The hydrolysis reaction takes 3 to 20 minutes. And / or, the hydrolysis reaction is carried out under stirring at a speed of 500 rpm to 2000 rpm.

9. The removal method as described in claim 1, characterized in that, The aging temperature is 30℃~90℃; And / or, the aging time is 0h to 48h, excluding 0h.

10. The removal method as described in claim 9, characterized in that, The aging temperature is 40℃~80℃; And / or, the aging time is 6h to 12h.

11. The removal method as described in claim 9 or 10, characterized in that, The aging process also includes stirring, and the stirring rate is 50 rpm to 300 rpm.

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