A method for producing high purity scandium oxide

Abstract

The application provides a method for preparing high-purity scandium oxide, comprising: mixing a scandium source with an acid solution to obtain a scandium-containing acid solution, using a composite targeting resin to perform targeted impurity removal treatment on the scandium-containing acid solution to obtain an impurity removal solution; adjusting the concentrations of hydrogen ions and chloride ions in the impurity removal solution, mixing the impurity removal solution with an HCl-NH4Cl composite agent to obtain a mixed solution, using a first extraction resin to perform extraction on the mixed solution to obtain a loaded organic phase, performing back extraction on the loaded organic phase to obtain a scandium-containing back extraction solution; using a second extraction resin to perform extraction treatment on the scandium-containing back extraction solution to obtain a scandium-rich solution, adjusting the pH of the scandium-rich solution, and performing a heating reaction to obtain high-purity scandium hydroxide, and calcining to obtain high-purity scandium oxide. 3+ [ScCl6] 3‑ complex ions, which greatly improves the impurity removal effect and prepares high-purity scandium oxide with a high recovery rate.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology and relates to a method for preparing high-purity scandium oxide. Background Technology

[0002] Scandium oxide, a scarce and strategically valuable rare earth oxide, possesses excellent optical, electrical, ceramic modification, and metallurgical strengthening properties, and is widely used in high-end aluminum-scandium alloys, solid-state fuel cells, laser crystals, aerospace, and semiconductor materials. With the continuous upgrading of high-end industrial technologies, the market demand for the purity of scandium oxide products continues to increase. The presence of trace impurities such as uranium, zirconium, and light rare earth elements can seriously affect the crystal structure, electrical stability, and service performance of scandium oxide, representing a key bottleneck restricting the industrial application of ultra-high purity scandium oxide. Currently, the raw material sources for industrial scandium oxide preparation are complex, mainly including crude scandium oxide, scandium chloride raw materials, titanium dioxide waste acid, and rare earth slag. These raw material systems have complex compositions and generally contain large amounts of impurity elements such as iron, aluminum, zirconium, uranium, and lanthanide rare earth elements. These impurities have similar physicochemical properties to scandium, making separation extremely difficult and posing a significant challenge to the purification and preparation of high-purity scandium oxide.

[0003] Existing scandium oxide purification processes mostly employ traditional techniques such as single-extractant extraction, ordinary homogeneous resin adsorption, and stepwise precipitation for impurity removal, which have significant technical defects and limitations. First, traditional purification systems lack targeted impurity removal mechanisms, relying mainly on a single extraction medium to remove impurities in a general manner. This fails to target and classify impurities of different types, such as uranium, zirconium, and rare earth elements, resulting in poor impurity removal selectivity and high residual levels of uranium, zirconium, and rare earth impurities, making it difficult to meet the requirements for preparing ultra-high purity scandium oxide. Simultaneously, traditional processes often employ multiple devices and steps for impurity removal, resulting in lengthy processes. Scandium is easily dissolved and lost during these multiple steps, significantly reducing the overall scandium recovery rate, leading to low production efficiency and severe raw material waste. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing high-purity scandium oxide. This invention significantly improves the removal rate of uranium, zirconium, and rare earth impurities in scandium solutions through multi-step, selective targeted extraction. Furthermore, by controlling the chloride ion concentration within the system, it promotes the removal of Sc... 3+ [ScCl6] is formed. 3- Complex ions enhance the binding ability with the extraction resin, significantly improving the impurity removal effect while achieving high recovery rate to prepare high-purity scandium oxide.

[0005] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for preparing high-purity scandium oxide, the method comprising the following steps: A scandium source is mixed with an acid solution to obtain a scandium-containing acid hydrolysate. The scandium-containing acid hydrolysate is then subjected to targeted impurity removal treatment using a composite targeted resin to obtain a purified solution. The concentrations of hydrogen ions and chloride ions in the impurity removal solution are adjusted, and the impurity removal solution is mixed with HCl-NH4Cl composite agent to obtain a mixed solution. The mixed solution is subjected to a first extraction treatment using a first extraction resin to obtain a loaded organic phase. The loaded organic phase is then back-extracted to obtain a scandium-containing back-extraction solution. The scandium-containing back-extraction solution was subjected to a second extraction treatment using a second extraction resin to obtain a scandium-rich solution. The pH of the scandium-rich solution was adjusted and heated to obtain high-purity scandium hydroxide. The high-purity scandium hydroxide was then calcined to obtain high-purity scandium oxide.

[0006] The high-purity scandium oxide described in this invention has a purity of not less than 99.99%, meeting the standard of Sc2O3-4N in GB / T13219-2018.

[0007] This invention first removes poorly soluble impurities by acid dissolution of the scandium source, then precisely adjusts the hydrogen and chloride ion concentrations of the scandium-containing acid hydrolysate to construct a basic media environment suitable for subsequent resin separation. A composite targeted resin is used to directionally remove various impurity metal ions (uranium, zirconium, and rare earth impurities). Next, an HCl-NH4Cl composite agent is used to provide a high-chlorine environment for the impurity removal solution, directionally generating scandium chloride complex anions. This significantly enhances the adsorption and binding force of the subsequent extraction resin on scandium, improving the scandium extraction rate. After selectively desorbing scandium using a specific back-extraction agent, the back-extraction solution is further extracted by a second extraction resin to deeply adsorb residual trace impurities, resulting in a high-purity scandium-rich solution. Finally, high-purity scandium oxide is obtained through alkalization precipitation and calcination.

[0008] Preferably, the scandium source includes any one or a combination of at least two of crude scandium oxide, scandium chloride, scandium-containing titanium dioxide waste acid, or scandium-containing rare earth slag. Typical but non-limiting combinations include combinations of crude scandium oxide and scandium chloride, combinations of scandium-containing titanium dioxide waste acid and scandium-containing rare earth slag, or combinations of crude scandium oxide and scandium-containing titanium dioxide waste acid, etc.

[0009] Preferably, the acid solution includes hydrochloric acid and / or sulfuric acid.

[0010] Preferably, the molar concentration of the acid solution is 2 mol / L to 12 mol / L, for example: 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L or 12 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0011] Preferably, the Fe in the scandium-containing acid hydrolysate 3+ and / or Al 3+ If the mass concentration is >0.1 g / L, the scandium acid hydrolysate is mixed with oxalic acid, stirred and reacted, and then filtered.

[0012] This invention contains Fe in scandium acid hydrolysate. 3+ and / or Al 3+ When the mass concentration is >0.1 g / L, oxalic acid can be added to selectively precipitate iron and aluminum impurity ions in order to reduce the difficulty of subsequent resin separation.

[0013] Preferably, the molar concentration of oxalic acid is 0.5 mol / L to 2 mol / L, for example: 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L or 2 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the stirring reaction time is 30 min to 60 min, for example: 30 min, 35 min, 40 min, 50 min or 60 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the composite targeting resin comprises a polystyrene-divinylbenzene carrier and a uranium removal layer, a zirconium removal layer, and a rare earth removal layer sequentially stacked on the surface of the polystyrene-divinylbenzene carrier.

[0016] This invention uses a composite targeted resin to complete the graded removal of multiple types of impurities through a single column. The resin stratification functions are independent and do not interfere with each other. The impurity removal selectivity is much higher than that of ordinary homogeneous extraction resins. It eliminates the need for multi-column series step-by-step processing, shortens the process, reduces scandium dissolution loss, and improves production efficiency.

[0017] Preferably, the material for removing the uranium layer includes N235 and TIOA with a mass ratio of (0.8~1.2):1, such as 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the material of the zirconium removal layer includes TBP.

[0019] Preferably, the material excluding the rare earth layer includes TBP and P350 with a mass ratio of (1.5~2.5):1, such as 1.5:1, 1.8:1, 2:1, 2.2:1 or 2.5:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the temperature of the targeted impurity removal process is 20℃~35℃, for example: 20℃, 22℃, 25℃, 30℃ or 35℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the O / A ratio of the targeted impurity removal process is (0.3~1):1, for example: 0.3:1, 0.4:1, 0.6:1, 0.8:1 or 1:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the targeted impurity removal process takes 8 to 25 minutes, for example, 8 minutes, 10 minutes, 15 minutes, 20 minutes, or 25 minutes, and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the molar concentration of hydrogen ions in the impurity removal solution is 2 mol / L to 5 mol / L, for example: 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the molar concentration of chloride ions in the impurity removal solution is 5 mol / L to 12 mol / L, for example: 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L or 12 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the molar ratio of HCl to NH4Cl in the HCl-NH4Cl composite agent is (3~5):1, for example: 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the HCl in the HCl-NH4Cl composite agent is added in the form of hydrochloric acid; Preferably, the molar concentration of the hydrochloric acid is 6 mol / L to 12 mol / L, such as 6 mol / L, 8 mol / L, 10 mol / L, or 12 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the molar concentration of hydrogen ions in the mixed solution is 3 mol / L to 8 mol / L, for example: 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L or 8 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the molar concentration of chloride ions in the mixed solution is 5 mol / L to 12 mol / L, for example: 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L or 12 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the extractant in the first extraction resin includes TRPO and TOPO.

[0030] Preferably, the mass ratio of TRPO to TOPO is (2~4):1, for example: 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] The TRPO-TOPO extraction resin used in this invention is a neutral phosphorus-oxygen complex extraction system, which has a strong coordination affinity for high-chlorine complexed scandium, thereby significantly improving the scandium extraction recovery rate while inhibiting the simultaneous adsorption of other residual impurities.

[0032] Preferably, the mass percentage of the extractant in the first extraction resin is 10% to 40%, for example: 10%, 20%, 30%, 35% or 40%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the extraction time is 10 min to 30 min, for example: 10 min, 15 min, 20 min, 25 min or 30 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, the stripping agent used in the stripping process comprises a mixed solution of sulfuric acid, citric acid, and concentrated nitric acid.

[0035] This invention uses a sulfuric acid + citric acid + nitrate composite back-extraction system to selectively desorb scandium, inhibit impurity back-extraction, and achieve high back-extraction selectivity, complete scandium back-extraction, and minimal impurity entrainment.

[0036] Preferably, the molar concentration of the sulfuric acid is 0.5 mol / L to 1.5 mol / L, for example: 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L or 1.5 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the molar concentration of the citric acid is 0.1 mol / L to 0.3 mol / L, for example: 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the volume ratio of sulfuric acid to citric acid in the mixed solution is (4~6):1, for example: 4:1, 4.5:1, 5:1, 5.5:1 or 6:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the molar concentration of nitrate in the mixed solution is 0.05 mol / L to 0.15 mol / L, for example: 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L or 0.15 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the extractant in the second extraction resin includes P350 and TRPO.

[0041] Preferably, the mass ratio of P350 to TRPO is (1~2):1, for example: 1:1, 1.2:1, 1.5:1, 1.8:1 or 2:1, etc.

[0042] This invention uses a P350 / TRPO compound extraction resin to deeply remove trace amounts of residual metal impurities, achieving an ultra-high purity level in the solution, thus laying the foundation for the subsequent preparation of ultra-high purity scandium oxide.

[0043] Preferably, the mass percentage of the extractant in the second extraction resin is 10% to 40%, for example: 10%, 20%, 30%, 35% or 40%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the second extraction time is 10 min to 30 min, for example: 10 min, 15 min, 20 min, 25 min or 30 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the pH adjuster for the scandium-rich solution includes ammonium bicarbonate solutions with a molar concentration of 0.5 mol / L to 1 mol / L, such as 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the pH is 6 to 6.5, for example: 6, 6.1, 6.2, 6.3 or 6.5, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the temperature of the heating reaction is 40℃~60℃, for example: 40℃, 45℃, 50℃, 55℃ or 60℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Preferably, the heating reaction time is 30 min to 45 min, for example: 30 min, 32 min, 35 min, 40 min or 45 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Preferably, the calcination process includes a first calcination and a second calcination performed sequentially.

[0050] Preferably, the temperature of the first calcination is 200℃~300℃, for example: 200℃, 220℃, 250℃, 280℃ or 300℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] Preferably, the holding time for the first calcination is 1h to 2h, for example: 1h, 1.2h, 1.5h, 1.8h or 2h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Preferably, the second calcination temperature is 800℃~900℃, for example: 800℃, 820℃, 850℃, 880℃ or 900℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] Preferably, the holding time for the second calcination is 2h to 3h, for example: 2h, 2.2h, 2.5h, 2.8h or 3h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] 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.

[0055] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention can significantly improve the removal rate of uranium, zirconium, and rare earth impurities in scandium solution through multi-step, selective targeted extraction, and promotes the removal of Sc by controlling the chloride ion concentration in the system.3+ [ScCl6] is formed. 3- Complex ions enhance the binding ability with the extraction resin, significantly improving the impurity removal effect while achieving high recovery rate to prepare high-purity scandium oxide.

[0056] (2) The high-purity scandium oxide prepared by the method of the present invention has a purity of not less than 99.992%, which meets the standard of Sc2O3-4N in GB / T 13219-2018, and the scandium element recovery rate is not less than 96.86%. Detailed Implementation

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology.

[0061] 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 according to its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order in which they are written or in any order that does not conflict with the technology.

[0062] The crude scandium oxide used in the embodiments and comparative examples of this invention has the following composition: Sc2O3: 93wt%, Fe2O3: 0.5wt%, Al2O3: 0.3wt%, ZrO2: 0.1wt%, UO2: 0.03wt%, ThO2: 0.01wt%, rare earth oxides: 0.8wt%, with the remainder being oxides of calcium, magnesium, silicon, etc.; the scandium-containing titanium dioxide waste acid has the following composition: Sc: 100mg / L, Ti: 10g / L, Fe: 50g / L, Al: 10g / L, Zr: 30mg / L, U: 2mg / L, Th: 0.5mg / L, H2SO4: 420g / L; the scandium-containing rare earth slag has the following composition: Sc2O3: 0.6wt%, rare earth oxides: 10wt%, Fe2O3: 28wt%, Al2O3: 15wt%, SiO2: 20wt%, CaO: 8wt%, ZrO2: 0.1wt%. wt%, UO2: 0.015wt%, ThO2: 0.005wt%.

[0063] Example 1 This embodiment provides a method for preparing high-purity scandium oxide, the method comprising the following steps: Crude scandium oxide was mixed with 5 mol / L hydrochloric acid and filtered to obtain a scandium-containing acid hydrolysate (the Fe in the scandium-containing acid hydrolysate was detected). 3+ And Al 3+ The total mass concentration was 0.01 g / L. A composite targeted resin (composite targeted resin includes a polystyrene-divinylbenzene carrier and N235 and TIOA uranium removal layer, TBP zirconium removal layer and TBP and P350 rare earth removal layer with a mass ratio of 1:1 stacked on the surface of the polystyrene-divinylbenzene carrier) was used to target and remove impurities from the scandium acid hydrolysate for 15 min at a controlled temperature of 30 °C and an O / A ratio of 0.5:1 to obtain the impurity-removed solution. A scandium-containing acid hydrolysate was obtained by adjusting the molar concentration of hydrogen ions to 2 mol / L and the molar concentration of chloride ions to 5 mol / L in the impurity removal solution. This solution was then mixed with an HCl-NH4Cl composite agent (HCl:NH4Cl molar ratio 4:1) to obtain a mixed solution with a hydrogen ion molar concentration of 3 mol / L and a chloride ion molar concentration of 8 mol / L. The mixed solution was subjected to a first extraction treatment for 20 min using an extraction resin (TRPO:TOPO mass ratio 3:1, extractant mass percentage 20%) to obtain a loaded organic phase. A mixed acid back-extraction agent (1 mol / L sulfuric acid, 0.2 mol / L citric acid volume ratio 5:1) was then added to obtain a nitrate molar concentration of 0.1 mol / L. This mixed acid back-extraction agent was used to back-extract the loaded organic phase to obtain a scandium-containing back-extraction solution. The scandium-containing back-extraction solution was subjected to a second extraction treatment for 20 min using an extraction resin with a mass ratio of P350 and TRPO of 1:1 (extractant mass percentage of 20%) to obtain a scandium-rich solution. The pH of the scandium-rich solution was adjusted to 6.2 using an ammonium bicarbonate solution with a molar concentration of 0.8 mol / L. The solution was then heated at 50 °C for 40 min to obtain high-purity scandium hydroxide. The high-purity scandium hydroxide was then calcined at 250 °C for 1.5 h, followed by a second calcination at 850 °C for 2.5 h to obtain high-purity scandium oxide.

[0064] Example 2 This embodiment provides a method for preparing high-purity scandium oxide, the method comprising the following steps: Scandium-containing titanium dioxide waste acid was mixed with 12 mol / L hydrochloric acid, and filtered to obtain a scandium-containing acid hydrolysate (Fe in the scandium-containing acid hydrolysate was detected). 3+ And Al 3+ The total mass concentration was 0.25 g / L. Oxalic acid with a molar concentration of 1 mol / L was added and stirred for 40 min before filtration. A composite targeted resin (composite targeted resin includes a polystyrene-divinylbenzene carrier and N235 and TIOA uranium removal layer, TBP zirconium removal layer and TBP and P350 rare earth removal layer with a mass ratio of 1.5:1 stacked on the surface of the polystyrene-divinylbenzene carrier in a mass ratio of 0.8:1) was used to target and remove impurities from the scandium acid hydrolysate for 25 min at a controlled temperature of 20℃ and an O / A ratio of 0.3:1 to obtain the impurity-removed solution. A scandium-containing acid hydrolysate was obtained by adjusting the molar concentration of hydrogen ions to 2 mol / L and the molar concentration of chloride ions to 5 mol / L in the impurity removal solution. This solution was then mixed with an HCl-NH4Cl composite agent (HCl and NH4Cl in a molar ratio of 3:1) to obtain a mixed solution with a hydrogen ion molar concentration of 8 mol / L and a chloride ion molar concentration of 5 mol / L. The mixed solution was subjected to a first extraction treatment for 10 min using an extraction resin (TRPO and TOPO in a mass ratio of 2:1, with an extractant mass percentage of 10%) to obtain a loaded organic phase. A mixed acid back-extraction agent (0.5 mol / L sulfuric acid and 0.1 mol / L citric acid in a volume ratio of 4:1) was then added to obtain a mixed acid back-extraction agent (0.05 mol / L nitrate). This mixed acid back-extraction agent was used to back-extract the loaded organic phase to obtain a scandium-containing back-extraction solution. The scandium-containing back-extraction solution was subjected to a second extraction treatment for 10 min using an extraction resin with a mass ratio of P350 and TRPO of 2:1 (extractant mass percentage of 10%) to obtain a scandium-rich solution. The pH of the scandium-rich solution was adjusted to 6.5 using an ammonium bicarbonate solution with a molar concentration of 0.5 mol / L. The solution was then heated at 40 °C for 45 min to obtain high-purity scandium hydroxide. After a first calcination of the high-purity scandium hydroxide at 200 °C for 2 h, a second calcination was performed at 800 °C for 3 h to obtain high-purity scandium oxide.

[0065] Example 3 This embodiment provides a method for preparing high-purity scandium oxide, the method comprising the following steps: Scandium-containing rare earth slag was mixed with sulfuric acid at a molar concentration of 2 mol / L, and filtered to obtain a scandium-containing acid hydrolysate (the Fe in the scandium-containing acid hydrolysate was detected). 3+ And Al 3+ The total mass concentration was 0.2 g / L. Oxalic acid with a molar concentration of 0.5 mol / L was added and stirred for 60 min before filtration. A composite targeted resin (composite targeted resin includes a polystyrene-divinylbenzene carrier and N235 and TIOA uranium removal layer, TBP zirconium removal layer and TBP and P350 rare earth removal layer with a mass ratio of 2.5:1 stacked on the surface of the polystyrene-divinylbenzene carrier in a mass ratio of 1.2:1) was used to target and remove impurities from the scandium acid hydrolysate for 8 min at a controlled temperature of 35℃ and an O / A ratio of 1:1 to obtain the impurity-removed solution. A scandium-containing acid hydrolysate was obtained by adjusting the molar concentration of hydrogen ions to 2 mol / L and the molar concentration of chloride ions to 5 mol / L in the impurity removal solution. This solution was then mixed with an HCl-NH4Cl composite agent (HCl:NH4Cl molar ratio 5:1) to obtain a mixed solution with a hydrogen ion molar concentration of 3 mol / L and a chloride ion molar concentration of 10 mol / L. The mixed solution was subjected to a first extraction treatment for 30 min using an extraction resin (TRPO:TOPO mass ratio 2.5:1, extractant mass percentage 40%) to obtain a loaded organic phase. A mixed acid back-extraction agent (1.5 mol / L sulfuric acid, 0.3 mol / L citric acid, 6:1 volume ratio) was then added to obtain a nitrate molar concentration of 0.08 mol / L. This mixed acid back-extraction agent was used to back-extract the loaded organic phase to obtain a scandium-containing back-extraction solution. The scandium-containing back-extraction solution was subjected to a second extraction treatment for 30 min using an extraction resin with a mass ratio of P350 to TRPO of 1.5:1 (extractant mass percentage of 40%) to obtain a scandium-rich solution. The pH of the scandium-rich solution was adjusted to 6 using a 1 mol / L ammonium bicarbonate solution, and the reaction was carried out at 60 °C for 30 min to obtain high-purity scandium hydroxide. The high-purity scandium hydroxide was then calcined at 300 °C for 1 h, followed by a second calcination at 900 °C for 2 h to obtain high-purity scandium oxide.

[0066] Example 4 The only difference between this embodiment and Embodiment 1 is that the molar concentration of chloride ions in the mixed solution is 3 mol / L, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0067] Example 5 The only difference between this embodiment and Embodiment 1 is that the mass ratio of TRPO to TOPO in the first extraction resin is 5:1, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0068] Example 6 The only difference between this embodiment and Embodiment 1 is that the mass ratio of TRPO to TOPO in the first extraction resin is 1:1, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0069] Example 7 The only difference between this embodiment and Embodiment 1 is that the mass ratio of P350 to TRPO in the second extraction resin is 0.5:1. All other conditions and parameters are exactly the same as in Embodiment 1.

[0070] Example 8 The only difference between this embodiment and Embodiment 1 is that the mass ratio of P350 to TRPO in the second extraction resin is 3:1. All other conditions and parameters are exactly the same as in Embodiment 1.

[0071] Comparative Example 1 The only difference between this comparative example and Example 1 is that the second extraction process is not performed; all other conditions and parameters are exactly the same as in Example 1.

[0072] Performance testing: The purity of the prepared scandium oxide was tested, and the recovery rate of scandium oxide was calculated. The test results are shown in Table 1. Table 1 As can be seen from Table 1, the high-purity scandium oxide prepared by the method of the present invention described herein has a purity of not less than 99.992%, which meets the standard of Sc2O3-4N in GB / T 13219-2018, and the scandium element recovery rate is not less than 96.86%.

[0073] A comparison of Examples 1 and 4 shows that, in the method for preparing high-purity scandium oxide described in this invention, adjusting the molar concentration of chloride ions in the impurity removal solution to 5 mol / L~12 mol / L can promote the complete removal of Sc. 3+ [ScCl6] is formed. 3- Complex ions enhance the binding ability with the extraction resin, thereby significantly improving the scandium recovery rate (no significant change when chloride ion concentration is too high).

[0074] A comparison of Examples 1 and 5-6 shows that in the method for preparing high-purity scandium oxide described in this invention, the mass ratio of TRPO to TOPO in the first extraction resin affects the impurity removal effect. Controlling the mass ratio of TRPO to TOPO at (2-4):1 results in a better impurity removal effect. If the proportion of TRPO is too high, the extraction selectivity decreases, the co-extraction of zirconium and rare earth impurities increases, and the purity decreases. If the proportion of TRPO is too low, the scandium extraction capacity is insufficient, and the recovery rate decreases.

[0075] A comparison of Examples 1 and 7-8 shows that in the method for preparing high-purity scandium oxide described in this invention, the mass ratio of P350 to TRPO in the second extraction resin affects the impurity removal effect. Controlling the mass ratio of P350 to TRPO at (1-2):1 results in a better impurity removal effect. If the proportion of P350 is too high, trace rare earth impurities will not be completely removed. If the proportion of P350 is too low, scandium loss will increase and the recovery rate will decrease.

[0076] As can be seen from the comparison between Example 1 and Comparative Example 1, the present invention further extracts and deeply adsorbs residual trace impurities by using a second extraction resin to extract the back-extraction liquid, thereby obtaining a high-purity scandium-rich solution and significantly improving the purity of the prepared scandium oxide.

[0077] 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 preparing high-purity scandium oxide, characterized in that, The method includes the following steps: A scandium source is mixed with an acid solution to obtain a scandium-containing acid hydrolysate. The scandium-containing acid hydrolysate is then subjected to targeted impurity removal treatment using a composite targeted resin to obtain a purified solution. The concentrations of hydrogen ions and chloride ions in the impurity removal solution are adjusted, and the impurity removal solution is mixed with HCl-NH4Cl composite agent to obtain a mixed solution. The mixed solution is subjected to a first extraction treatment using a first extraction resin to obtain a loaded organic phase. The loaded organic phase is then back-extracted to obtain a scandium-containing back-extraction solution. The scandium-containing back-extraction solution was subjected to a second extraction treatment using a second extraction resin to obtain a scandium-rich solution. The pH of the scandium-rich solution was adjusted and heated to obtain high-purity scandium hydroxide. The high-purity scandium hydroxide was then calcined to obtain high-purity scandium oxide.

2. The method as described in claim 1, characterized in that, The scandium source includes any one or a combination of at least two of the following: crude scandium oxide, scandium chloride, scandium-containing titanium dioxide waste acid, or scandium-containing rare earth slag. Preferably, the acid solution comprises hydrochloric acid and / or sulfuric acid; Preferably, the molar concentration of the acid solution is 2 mol / L to 12 mol / L; Preferably, the Fe in the scandium-containing acid hydrolysate 3+ and / or Al 3+ If the mass concentration is >0.1 g / L, the scandium-containing hydrolysate is mixed with oxalic acid, stirred and reacted, and then filtered. Preferably, the molar concentration of the oxalic acid is 0.5 mol / L to 2 mol / L; Preferably, the stirring reaction time is 30 min to 60 min.

3. The method as described in claim 1 or 2, characterized in that, The composite targeting resin includes a polystyrene-divinylbenzene carrier and a uranium removal layer, a zirconium removal layer, and a rare earth removal layer sequentially stacked on the surface of the polystyrene-divinylbenzene carrier. Preferably, the material used to remove the uranium layer comprises N235 and TIOA in a mass ratio of (0.8~1.2):1; Preferably, the material of the zirconium removal layer includes TBP; Preferably, the material excluding the rare earth layer comprises TBP and P350 in a mass ratio of (1.5~2.5):

1.

4. The method according to any one of claims 1-3, characterized in that, The temperature for the targeted impurity removal process is 20℃~35℃; Preferably, the O / A ratio of the targeted impurity removal process is (0.3~1):1; Preferably, the targeted impurity removal process takes 8 to 25 minutes.

5. The method according to any one of claims 1-4, characterized in that, The molar concentration of hydrogen ions in the impurity removal solution is adjusted to be 2 mol / L to 5 mol / L; Preferably, the molar concentration of chloride ions in the impurity removal solution is 5 mol / L to 12 mol / L.

6. The method according to any one of claims 1-5, characterized in that, The molar ratio of HCl to NH4Cl in the HCl-NH4Cl composite agent is (3~5):1; Preferably, the HCl in the HCl-NH4Cl composite agent is added in the form of hydrochloric acid; Preferably, the molar concentration of the hydrochloric acid is 6 mol / L to 12 mol / L; Preferably, the molar concentration of hydrogen ions in the mixed solution is 3 mol / L to 8 mol / L; Preferably, the molar concentration of chloride ions in the mixed solution is 5 mol / L to 12 mol / L.

7. The method according to any one of claims 1-6, characterized in that, The extractants in the first extraction resin include TRPO and TOPO; Preferably, the mass ratio of TRPO to TOPO is (2~4):1; Preferably, the mass percentage of the extractant in the first extraction resin is 10% to 40%; Preferably, the first extraction process takes 10 to 30 minutes.

8. The method according to any one of claims 1-7, characterized in that, The back-extraction agent used in the back-extraction process includes a mixed solution of sulfuric acid, citric acid, and concentrated nitric acid; Preferably, the molar concentration of the sulfuric acid is 0.5 mol / L to 1.5 mol / L; Preferably, the molar concentration of the citric acid is 0.1 mol / L to 0.3 mol / L; Preferably, the volume ratio of sulfuric acid to citric acid in the mixed solution is (4~6):1; Preferably, the molar concentration of nitrate in the mixed solution is 0.05 mol / L to 0.15 mol / L.

9. The method according to any one of claims 1-8, characterized in that, The extractants in the second extraction resin include P350 and TRPO; Preferably, the mass ratio of P350 to TRPO is (1~2):1; Preferably, the extractant in the second extraction resin has a mass percentage content of 10% to 40%; Preferably, the second extraction process takes 10 to 30 minutes.

10. The method according to any one of claims 1-9, characterized in that, The pH adjuster for the scandium-rich solution includes an ammonium bicarbonate solution with a molar concentration of 0.5 mol / L to 1 mol / L. Preferably, the pH is 6 to 6.5; Preferably, the temperature of the heating reaction is 40°C to 60°C; Preferably, the heating reaction time is 30 min to 45 min; Preferably, the calcination treatment includes a first calcination and a second calcination performed sequentially; Preferably, the temperature of the first calcination is 200℃~300℃; Preferably, the holding time for the first calcination is 1 hour to 2 hours; Preferably, the second calcination temperature is 800℃~900℃; Preferably, the heat preservation time for the second calcination is 2h to 3h.

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