A process for the production of high purity scandia from a scandium-containing organic phase

Abstract

The application provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase, which comprises the following steps: mixing the scandium-containing organic phase with a phosphoric acid solution to perform back extraction to obtain a first scandium-containing solution with scandium-containing complexes; performing alkali precipitation on the first scandium-containing solution to obtain a scandium hydroxide precipitate; performing acid dissolution on the scandium hydroxide precipitate to obtain a second scandium-containing solution; and sequentially performing oxalic acid precipitation treatment and calcination on the second scandium-containing solution to obtain high-purity scandium oxide. The application can realize efficient back extraction of scandium, and can obtain high-purity scandium oxide products through a short process procedure, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of rare earth organic extraction and purification technology, and in particular to a method for preparing high-purity scandium oxide from scandium-containing organic phases. Background Technology

[0002] Scandium (Sc), as a key strategic element in the rare earth family, plays an irreplaceable role in high-tech fields such as aerospace, solid-state lasers, high-performance alloys, and solid oxide fuel cells due to its unique physicochemical properties.

[0003] With the rapid development of industries such as new energy and electronic information, global demand for high-purity scandium and its compounds continues to grow. However, scandium is highly dispersed in the Earth's crust, rarely forming independent deposits, and is mainly associated with minerals such as tungsten, tin, titanium, zirconium, and laterite nickel ore. Currently, most scandium supply comes from the recovery of byproducts from the processing of these minerals. For example, slag or waste liquid generated during the smelting of laterite nickel ore often contains 50–600 g / ton of scandium, making it an important potential source of scandium. Efficiently separating and purifying scandium from these complex systems, especially efficiently back-extracting it from the scandium-containing organic phase after extraction, is a key step in achieving comprehensive utilization of scandium resources.

[0004] In hydrometallurgy, solvent extraction is the mainstream process for separating and enriching scandium. However, the back-extraction step has always been a bottleneck in scandium extraction systems. Currently, the commonly used back-extraction methods in industry mainly have the following limitations:

[0005] 1. Alkali back-extraction (such as NaOH solution) or oxalic acid back-extraction: Although scandium can be precipitated in the form of hydroxide or oxalate, the reaction process easily forms a three-phase mixture of oil, liquid and solid, which is difficult to separate. In addition, it usually requires high temperature, consumes a lot of energy and has a complex operating environment.

[0006] 2. Strong inorganic acid back-extraction (such as hydrochloric acid and sulfuric acid): High concentrations of acid (usually >4 mol / L) are required to achieve effective scandium back-extraction, resulting in excessively high acidity of the back-extraction solution, severe co-extraction of impurities, and generally low scandium concentration in the back-extraction solution (usually below 5 g / L). This leads to high subsequent processing costs and exacerbates equipment corrosion and environmental pollution.

[0007] The above methods generally suffer from problems such as low back-extraction efficiency, harsh process conditions, limited product purity, high operating costs, or poor environmental friendliness, which restrict the efficient and green extraction and high purification of scandium.

[0008] Therefore, developing a novel back-extraction process with mild back-extraction conditions, high back-extraction efficiency, good selectivity, and easy post-processing is of great significance for improving the economics and product quality of scandium recovery. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing high-purity scandium oxide from scandium-containing organic phase. This method has mild back-extraction conditions, high back-extraction efficiency, good selectivity, and is easy to prepare high-purity scandium oxide in subsequent processes, thereby improving the economic efficiency of scandium recovery and product quality.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] This invention provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase, the method comprising the following steps:

[0012] The scandium-containing organic phase was mixed with a phosphoric acid solution and back-extracted to obtain a first scandium-containing solution with a scandium-containing complex.

[0013] The first scandium-containing solution was subjected to alkaline precipitation to obtain scandium hydroxide precipitate.

[0014] The scandium hydroxide precipitate was dissolved in acid to obtain a second scandium-containing solution.

[0015] The second scandium-containing solution was subjected to oxalic acid precipitation and calcination in sequence to obtain high-purity scandium oxide.

[0016] This invention extracts scandium from a scandium-containing organic phase using a phosphoric acid solution, forming a scandium-containing complex (Sc(H₂PO₄)₃) with the phosphate ion. The phosphoric acid solution specifically complexes with scandium, achieving highly efficient selective back-extraction and providing a foundation for subsequent separation and purification. The phosphate ion in this scandium-containing complex exhibits strong binding force with scandium; oxalic acid cannot convert the scandium in the complex to scandium oxalate. However, direct alkaline precipitation can convert the scandium-containing complex into scandium hydroxide precipitate. Further acid dissolution and oxalic acid precipitation are then used to improve the purity of the final scandium oxide product.

[0017] Preferably, the organic phase in the scandium-containing organic phase includes any one or a combination of at least two of P204, P507, Cyanex272, P350, or N1923.

[0018] Preferably, the scandium concentration in the scandium-containing organic phase is 5~15 g / L.

[0019] Preferably, the concentration of the phosphoric acid solution is 1~2 mol / L.

[0020] Preferably, the volume ratio of the scandium-containing organic phase to the phosphoric acid solution is 3:1 to 1:3.

[0021] Preferably, the back-extraction temperature is 25~50℃.

[0022] Preferably, the back-extraction time is 30-60 minutes.

[0023] Preferably, the back-extraction is carried out under stirring.

[0024] Preferably, the stirring speed during the back-extraction is 100~300 rpm.

[0025] Preferably, the alkaline precipitation includes adjusting the pH of the first scandium-containing solution to 7-11 using ammonia.

[0026] Preferably, the temperature of the alkali precipitation is 50~80℃.

[0027] Preferably, the reaction time for alkali precipitation is 1 to 3 hours.

[0028] Preferably, the method further includes: performing solid-liquid separation on the material after alkali precipitation, and washing the obtained solid phase.

[0029] Preferably, the washing includes at least three washes.

[0030] Preferably, the acid dissolution includes mixing scandium hydroxide precipitate with an acid solution.

[0031] Preferably, the acid solution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, or nitric acid.

[0032] Preferably, the solid-liquid ratio of the scandium hydroxide precipitate to the acid solution is 1:(1~3)mg / L.

[0033] Preferably, the pH of the second scandium-containing solution is 0 to 1.

[0034] Preferably, the acid dissolution temperature is 30~60℃.

[0035] Preferably, the oxalic acid precipitation treatment includes: a second scandium-containing solution reacting with oxalic acid to form a precipitation reaction.

[0036] Preferably, the mass ratio of oxalic acid to scandium in the second scandium-containing solution is (3~6):1.

[0037] Preferably, the precipitation reaction is carried out at a temperature of 50~80℃.

[0038] Preferably, the precipitation reaction takes 1 to 3 hours.

[0039] Preferably, the method further includes washing the obtained precipitated solid phase between the oxalic acid precipitation treatment and calcination.

[0040] Preferably, the calcination temperature is 800~1000℃.

[0041] Preferably, the roasting time is 2 to 6 hours.

[0042] Preferably, the roasting atmosphere includes an oxygen-containing atmosphere.

[0043] Preferably, the purity of the high-purity scandium oxide is ≥99.95wt%.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] (1) The method for preparing high-purity scandium oxide from scandium-containing organic phase provided by the present invention has high selectivity for scandium in back-extraction and simple subsequent separation process;

[0046] (2) The method for preparing high-purity scandium oxide from scandium-containing organic phase provided by the present invention has a mild back-extraction process, and high-purity scandium oxide can be obtained by subsequent alkaline precipitation, acid dissolution, oxalic acid precipitation and calcination. The purity of high-purity scandium oxide is preferably above 99.95 wt%, and the scandium recovery rate is preferably above 95%. Attached Figure Description

[0047] Figure 1 This is a schematic flowchart of the method for preparing high-purity scandium oxide from a scandium-containing organic phase provided by the present invention. Detailed Implementation

[0048] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0049] It should be understood that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] As a specific embodiment of the present invention, a method for preparing high-purity scandium oxide from a scandium-containing organic phase is provided, the method comprising the following steps:

[0051] The scandium-containing organic phase was mixed with a phosphoric acid solution and back-extracted to obtain a first scandium-containing solution with a scandium-containing complex.

[0052] The first scandium-containing solution was subjected to alkaline precipitation to obtain scandium hydroxide precipitate.

[0053] The scandium hydroxide precipitate was dissolved in acid to obtain a second scandium-containing solution.

[0054] The second scandium-containing solution was subjected to oxalic acid precipitation and calcination in sequence to obtain high-purity scandium oxide.

[0055] This invention extracts scandium from a scandium-containing organic phase using a phosphoric acid solution, forming a scandium-containing complex (Sc(H₂PO₄)₃) with the phosphate ion. The phosphoric acid solution specifically complexes with scandium, achieving highly efficient selective back-extraction and providing a foundation for subsequent separation and purification. The phosphate ion in this scandium-containing complex exhibits strong binding force with scandium; oxalic acid cannot convert the scandium in the complex into scandium oxalate. However, direct alkaline precipitation can convert the scandium-containing complex into scandium hydroxide precipitate. Further treatment with acid dissolution (removing impurities such as iron and aluminum) and oxalic acid precipitation further improves the purity of the final scandium oxide product.

[0056] Preferably, the organic phase in the scandium-containing organic phase includes any one or a combination of at least two of P204, P507, Cyanex272, P350, or N1923, wherein typical but non-limiting combinations are combinations of P204 and P507, combinations of Cyanex272 and P507, combinations of P204 and Cyanex272, combinations of N1923 and P507, combinations of P204 and P350, and combinations of P350 and P507.

[0057] The present invention preferably uses scandium-containing organic phases within the above-mentioned range, which is more conducive to subsequent back-extraction with phosphoric acid solution. For other scandium-containing organic phases, the back-extraction effect with phosphoric acid solution is not good.

[0058] Preferably, the scandium concentration in the scandium-containing organic phase is 5~15 g / L, for example, it can be 5 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L or 15 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the concentration of the phosphoric acid solution is 1~2 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L or 2 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] The present invention preferably controls the concentration of the phosphoric acid solution within the above-mentioned range, which can improve the recovery rate and selectivity of Sc and improve the purity of the product.

[0061] Preferably, the volume ratio of the scandium-containing organic phase to the phosphoric acid solution is 3:1 to 1:3, for example, it can be 3:1, 2.8:1, 2.7:1, 2.5:1, 2.2:1, 2.1:1, 1.9:1, 1.8:1, 1.5:1, 1.2:1, 1:1, 2.5:3, 2.2:3, 2:3, 1.8:3, 1.5:3, 1.2:3 or 1:3, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0062] The present invention preferably controls the volume ratio of scandium-containing organic phase to phosphoric acid solution within a reasonable range, which can better improve the back-extraction effect and increase the recovery rate of Sc; and effectively control the concentration of Sc in the back-extraction solution, thereby controlling the amount of alkali used in subsequent alkaline precipitation, while taking cost into consideration.

[0063] Preferably, the back-extraction temperature is 25~50℃, for example, it can be 25℃, 28℃, 31℃, 34℃, 37℃, 39℃, 42℃, 45℃, 48℃ or 50℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0064] Preferably, the back-extraction time is 30 to 60 minutes, for example, it can be 30 minutes, 34 minutes, 37 minutes, 40 minutes, 44 minutes, 47 minutes, 50 minutes, 54 minutes, 57 minutes or 60 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0065] Preferably, the back-extraction is carried out under stirring.

[0066] Preferably, the stirring speed during the back-extraction is 100~300 rpm, for example, it can be 100 rpm, 120 rpm, 145 rpm, 160 rpm, 180 rpm, 210 rpm, 230 rpm, 250 rpm, 270 rpm or 300 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0067] Preferably, the alkaline precipitation includes adjusting the pH of the first scandium-containing solution to 7-11 with ammonia water, for example, 7, 7.5, 7.9, 8.4, 8.8, 9.3, 9.7, 10.2, 10.6 or 11, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] When the pH of alkaline precipitation is too low, scandium hydroxide precipitation is incomplete, resulting in a large loss of scandium in the mother liquor and a reduced recovery rate. When the pH of alkaline precipitation is too high, it may cause the redissolution of certain amphoteric impurities or the formation of colloids. At the same time, excessive ammonia water increases costs and may introduce new impurities, leading to a decrease in the purity of the final product.

[0069] Preferably, the temperature of the alkali precipitation is 50~80℃, for example, it can be 50℃, 54℃, 57℃, 60℃, 64℃, 67℃, 70℃, 74℃, 77℃ or 80℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0070] Preferably, the reaction time for alkali precipitation is 1 to 3 hours, for example, it can be 1 hour, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0071] Preferably, the method further includes: performing solid-liquid separation on the material after alkali precipitation, and washing the obtained solid phase.

[0072] Preferably, the washing includes at least three washes.

[0073] Preferably, the acid dissolution includes mixing scandium hydroxide precipitate with an acid solution.

[0074] Preferably, the acid solution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, or nitric acid.

[0075] Preferably, the solid-liquid ratio of the scandium hydroxide precipitate to the acid solution is 1:(1~3) mg / L, for example, it can be 1:1 mg / L, 1:1.2 mg / L, 1:1.3 mg / L, 1:1.4 mg / L, 1:1.5 mg / L, 1:1.8 mg / L, 1:1.9 mg / L, 1:2.0 mg / L, 1:2.2 mg / L, 1:2.3 mg / L, 1:2.5 mg / L, 1:2.8 mg / L or 1:3 mg / L, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0076] Preferably, the pH of the second scandium-containing solution is 0 to 1, for example, it can be 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0077] The present invention preferably controls the pH of the second scandium-containing solution within the above-mentioned range, which is conducive to the full precipitation of scandium hydroxide and ensures the scandium recovery rate.

[0078] Preferably, the acid dissolution temperature is 30~60℃, for example, it can be 30℃, 34℃, 37℃, 40℃, 44℃, 47℃, 50℃, 54℃, 57℃ or 60℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0079] Preferably, the oxalic acid precipitation treatment includes: a second scandium-containing solution reacting with oxalic acid to form a precipitation reaction.

[0080] Preferably, the mass ratio of oxalic acid to scandium in the second scandium-containing solution is (3~6):1, for example, it can be 3:1, 3.4:1, 3.7:1, 4:1, 4.4:1, 4.7:1, 5:1, 5.4:1, 5.7:1 or 6:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0081] Preferably, the temperature of the precipitation reaction is 50~80℃, for example, it can be 50℃, 54℃, 57℃, 60℃, 64℃, 67℃, 70℃, 74℃, 77℃ or 80℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0082] Preferably, the precipitation reaction time is 1 to 3 hours, for example, 1 hour, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0083] Preferably, the method further includes washing the obtained precipitated solid phase between the oxalic acid precipitation treatment and calcination.

[0084] Preferably, the roasting temperature is 800~1000℃, for example, it can be 800℃, 820℃, 845℃, 860℃, 880℃, 910℃, 930℃, 950℃, 970℃ or 1000℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0085] Preferably, the roasting time is 2 to 6 hours, for example, it can be 2 hours, 2.5 hours, 2.9 hours, 3.4 hours, 3.8 hours, 4.3 hours, 4.7 hours, 5.2 hours, 5.6 hours or 6 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0086] Preferably, the roasting atmosphere includes an oxygen-containing atmosphere.

[0087] Preferably, the purity of the high-purity scandium oxide is ≥99.95wt%, for example, it can be 99.95wt%, 99.96wt%, 99.97wt%, 99.98wt%, or 99.99wt%.

[0088] As a preferred technical solution of the present invention, such as Figure 1 As shown, the method includes the following steps:

[0089] A scandium-containing organic phase with a scandium mass concentration of 5-15 g / L is mixed with a 1-2 mol / L phosphoric acid solution and back-extracted at 25-50 °C and 100-300 r / min for 30-60 min, wherein the volume ratio of the scandium-containing organic phase to the phosphoric acid solution is 3:1-1:3, to obtain a first scandium-containing solution with a scandium-containing complex.

[0090] The pH of the first scandium-containing solution was adjusted to 7-11 with ammonia water at 50-80℃ for alkali precipitation for 1-3 hours. The material after alkali precipitation was subjected to solid-liquid separation, and the obtained solid phase was washed to obtain scandium hydroxide precipitate.

[0091] The scandium hydroxide precipitate was mixed with acid solution at a solid-liquid ratio of 1:(1~3)mg / L and acid dissolved at 30~60℃ to obtain a second scandium-containing solution with a pH of 0~1.

[0092] The second scandium-containing solution is subjected to oxalic acid precipitation treatment, which includes: reacting the second scandium-containing solution with oxalic acid at 50~80℃ for 1~3h, with the mass ratio of oxalic acid to scandium in the second scandium-containing solution being (3~6):1; washing the obtained precipitated solid phase; and calcining the washed precipitated solid phase at 800~1000℃ in an oxygen-containing atmosphere for 2~6h to obtain high-purity scandium oxide with a purity ≥99.95wt%.

[0093] The present invention does not impose any special restrictions on the solid-liquid separation in the above process. Any device and method known to those skilled in the art for solid-liquid separation can be used. It can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0094] The present invention does not impose any special restrictions on the washing process described above. Any device and method known to those skilled in the art for washing can be used. Adjustments can also be made according to the actual process. For example, it can be rinsing, soaking, or showering, or a combination of different methods.

[0095] The method for preparing high-purity scandium oxide from scandium-containing organic phases provided by the specific embodiments of the present invention uses low-acidity phosphoric acid as the back-extraction agent. The scandium concentration in the back-extraction solution can reach more than 15 g / L, realizing efficient back-extraction of scandium in the scandium extraction system. The scandium phosphate solution after phosphoric acid back-extraction can be used to prepare high-purity scandium oxide products through alkaline precipitation, acid dissolution, oxalic acid precipitation and calcination processes.

[0096] The following detailed description uses specific examples.

[0097] Example 1

[0098] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase, the method comprising the following steps:

[0099] A scandium-containing organic phase (organic extractant P507) with a scandium mass concentration of 9 g / L was mixed with a 1.5 mol / L phosphoric acid solution and back-extracted at 35 °C and 100 r / min for 40 min, wherein the volume ratio of the scandium-containing organic phase to the phosphoric acid solution was 2:1, to obtain a first scandium-containing solution with a scandium complex.

[0100] The pH of the first scandium-containing solution was adjusted to 10 with ammonia at 60°C for alkali precipitation for 2 hours. The material after alkali precipitation was filtered, and the obtained solid phase was washed (washed with water at least three times) to obtain scandium hydroxide precipitate.

[0101] The scandium hydroxide precipitate was mixed with an acid solution (a 2 mol / L sulfuric acid solution) at a solid-liquid ratio of 1:2 mg / L and dissolved at 45°C to obtain a second scandium-containing solution with a pH of 0.5.

[0102] The second scandium-containing solution is subjected to oxalic acid precipitation treatment, which includes: reacting the second scandium-containing solution with oxalic acid at 60°C for 2 hours, wherein the mass ratio of oxalic acid to scandium in the second scandium-containing solution is 4:1; washing the obtained precipitated solid phase; and calcining the washed precipitated solid phase at 900°C for 3 hours in an oxygen-containing atmosphere to obtain high-purity scandium oxide.

[0103] Example 2

[0104] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase, the method comprising the following steps:

[0105] A scandium-containing organic phase (organic extractant is P204) with a scandium mass concentration of 6 g / L was mixed with a 1.0 mol / L phosphoric acid solution and back-extracted at 25 °C and 150 r / min for 60 min, wherein the volume ratio of the scandium-containing organic phase to the phosphoric acid solution was 3:1, to obtain a first scandium-containing solution with a scandium complex.

[0106] The pH of the first scandium-containing solution was adjusted to 11 with ammonia at 50°C for alkali precipitation for 1 hour. The material after alkali precipitation was filtered, and the obtained solid phase was washed (washed with water at least three times) to obtain scandium hydroxide precipitate.

[0107] The scandium hydroxide precipitate was mixed with an acid solution (a 1 mol / L sulfuric acid solution) at a solid-liquid ratio of 1:3 mg / L and dissolved at 30°C to obtain a second scandium-containing solution with a pH of 1.

[0108] The second scandium-containing solution is subjected to oxalic acid precipitation treatment, which includes: reacting the second scandium-containing solution with oxalic acid at 50°C for 3 hours, with the mass ratio of oxalic acid to scandium in the second scandium-containing solution being 6:1; washing the obtained precipitated solid phase; and calcining the washed precipitated solid phase at 1000°C for 2 hours in an oxygen-containing atmosphere to obtain high-purity scandium oxide.

[0109] Example 3

[0110] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase, the method comprising the following steps:

[0111] Scandium-containing organic phase (organic extractant: Cyanex 272) with a scandium mass concentration of 15 g / L was mixed with 2.0 mol / L phosphoric acid solution and back-extracted at 50 °C and 300 r / min for 30 min, wherein the volume ratio of scandium-containing organic phase to phosphoric acid solution was 1:1, to obtain a first scandium-containing solution with scandium complex.

[0112] The pH of the first scandium-containing solution was adjusted to 7 with ammonia at 80°C for alkali precipitation for 3 hours. The material after alkali precipitation was filtered, and the obtained solid phase was washed (washed with water at least four times) to obtain scandium hydroxide precipitate.

[0113] The scandium hydroxide precipitate was mixed with an acid solution (a 3 mol / L sulfuric acid solution) at a solid-liquid ratio of 1:1 mg / L and dissolved at 60°C to obtain a second scandium-containing solution with a pH of 0.

[0114] The second scandium-containing solution is subjected to oxalic acid precipitation treatment, which includes: reacting the second scandium-containing solution with oxalic acid at 80°C for 1 hour, wherein the mass ratio of oxalic acid to scandium in the second scandium-containing solution is 3:1; washing the obtained precipitated solid phase; and calcining the washed precipitated solid phase at 800°C for 6 hours in an oxygen-containing atmosphere to obtain high-purity scandium oxide.

[0115] Example 4

[0116] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the use of CA100 as the organic extractant, the method is the same as that in Example 1 and will not be repeated here.

[0117] Example 5

[0118] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the volume ratio of the scandium-containing organic phase to the phosphoric acid solution being 4:1, the method is the same as in Example 1 and will not be repeated here.

[0119] Example 6

[0120] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the volume ratio of the scandium-containing organic phase to the phosphoric acid solution being 0.5:3, the method is the same as in Example 1 and will not be repeated here.

[0121] Example 7

[0122] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the concentration of the phosphoric acid solution being 0.5 mol / L, the method is the same as in Example 1 and will not be repeated here.

[0123] Example 8

[0124] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the concentration of the phosphoric acid solution being 2.5 mol / L, the method is the same as in Example 1 and will not be repeated here.

[0125] Example 9

[0126] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the pH of the alkaline precipitation being 6.0, the method is the same as in Example 1 and will not be repeated here.

[0127] Example 10

[0128] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the pH of the alkaline precipitation being 12, the method is the same as that in Example 1, and will not be repeated here.

[0129] Example 11

[0130] This embodiment provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. Except for the pH of the acid dissolution being 1.5, the method is the same as in Example 1 and will not be repeated here.

[0131] Comparative Example 1

[0132] This comparative example provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. The method is the same as in Example 1, except that the phosphoric acid solution is replaced with a sulfuric acid solution of equal concentration. It will not be described again here.

[0133] Comparative Example 2

[0134] This comparative example provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. The method is the same as in Example 1 except that the first scandium-containing solution is directly treated with oxalic acid instead of alkaline precipitation and acid dissolution. Therefore, it will not be described again here.

[0135] Comparative Example 3

[0136] This comparative example provides a method for preparing high-purity scandium oxide from a scandium-containing organic phase. The method is the same as in Example 1, except that a 100 g / L oxalic acid solution is directly used to replace the phosphoric acid solution for back-extraction. Therefore, it will not be described again here.

[0137] Test methods: The concentration of scandium in the back-extraction solution was determined by ICP-OES. The purity of high-purity scandium oxide was determined by ICP-MS, and the recovery rate of scandium from the scandium-containing organic phase was also determined.

[0138] The test results of the above embodiments and comparative examples are shown in Table 1.

[0139] Table 1

[0140]

[0141] The following points can be observed from Table 1:

[0142] (1) As can be seen from Examples 1 to 3, the method for preparing high-purity scandium oxide from scandium-containing organic phase provided by the present invention can improve the concentration of scandium in the back-extraction solution and the scandium recovery rate. The concentration of scandium in the back-extraction solution is above 14.5 g / L, the purity of high-purity scandium oxide is above 99.9 wt%, and the scandium recovery rate is above 95.8%.

[0143] (2) As can be seen from Examples 1 and 4, when using the same back-extraction process, the back-extraction effect decreases significantly when the organic extractant in the scandium-containing organic phase is different. This indicates that the phosphoric acid solution back-extraction method of the present invention is specifically designed for a particular organic phase and has a better back-extraction effect.

[0144] (3) As can be seen from Examples 1 and 5-6, the volume ratio of scandium-containing organic phase to phosphoric acid solution in Example 1 is 2:1, which is higher than the 4:1 and 0.5:3 ratios in Examples 5-6, respectively. The scandium recovery rate in Example 1 is as high as 96.5%, while the scandium recovery rates in Examples 5-6 are only 68.8% and 90.7%, respectively. This shows that the present invention preferably controls the volume ratio of scandium-containing organic phase to phosphoric acid solution within a reasonable range, which can better improve the scandium recovery rate.

[0145] (4) As can be seen from Examples 1 and 7-8, the concentration of phosphoric acid solution in Example 1 is 1.5 mol / L, compared with 0.5 mol / L and 2.5 mol / L in Examples 7-8, respectively. In Example 1, the scandium recovery rate is as high as 96.5%, and the purity of high-purity scandium oxide is 99.97 wt%. In contrast, the scandium recovery rate in Example 7 is only 85.6%, and the scandium purity in Example 8 is only 99.82 wt%. This indicates that the present invention preferably controls the concentration of phosphoric acid solution within a reasonable range, which can better improve the scandium recovery rate and the purity of scandium oxide.

[0146] (5) As can be seen from Examples 1 and 9-10, the pH of the alkaline precipitation in Example 1 was 10, compared with the pH of 6.0 and 12 in Examples 9-10, respectively. In Example 1, the scandium recovery rate was as high as 96.5%, and the purity of high-purity scandium oxide was 99.97 wt%. In contrast, the scandium recovery rate in Example 9 was only 93.1%, and the purity of scandium oxide was only 99.87 wt%. In Example 10, the scandium recovery rate was only 95.1 wt%. This indicates that the present invention preferably controls the pH of the alkaline precipitation within a reasonable range, which can better improve the scandium recovery rate and the purity of scandium oxide.

[0147] (6) Combining Examples 1 and 11, it can be seen that the pH of acid dissolution in Example 1 is 0.5, compared with the pH of acid dissolution in Example 11 being 1.5. In Example 1, the scandium recovery rate is as high as 96.5%, and the purity of high-purity scandium oxide is 99.97 wt%. In contrast, in Example 11, scandium hydroxide was not completely dissolved, resulting in a low scandium recovery rate of only 93.4 wt%. This indicates that the present invention preferably controls the pH of acid dissolution within a reasonable range, which can better improve the scandium recovery rate.

[0148] (7) In Comparative Example 1, replacing the phosphoric acid solution with a sulfuric acid solution of equal concentration resulted in poor back-extraction, with a final scandium recovery rate of only 13.4%. In Comparative Example 2, instead of alkaline precipitation and acid dissolution, the first scandium-containing solution was directly treated with oxalic acid, resulting in no scandium hydroxide precipitate and a low scandium recovery rate. In Comparative Example 3, back-extraction was performed using oxalic acid solution, but the back-extraction effect was poor. This demonstrates that the present invention, by using phosphoric acid solution for back-extraction and combining it with a specific process flow, can achieve efficient scandium recovery and obtain high-purity scandium oxide products, showing broad application prospects.

[0149] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing high-purity scandium oxide from a scandium-containing organic phase, characterized in that, The method includes the following steps: The scandium-containing organic phase was mixed with a phosphoric acid solution and back-extracted to obtain a first scandium-containing solution with a scandium-containing complex. The first scandium-containing solution was subjected to alkaline precipitation to obtain scandium hydroxide precipitate; The scandium hydroxide precipitate was dissolved in acid to obtain a second scandium-containing solution; The second scandium-containing solution was subjected to oxalic acid precipitation and calcination in sequence to obtain high-purity scandium oxide.

2. The method according to claim 1, characterized in that, The scandium-containing organic phase includes any one or a combination of at least two of P204, P507, Cyanex272, P350, or N1923; Preferably, the scandium concentration in the scandium-containing organic phase is 5~15 g / L.

3. The method according to claim 1 or 2, characterized in that, The concentration of the phosphoric acid solution is 1~2 mol / L; Preferably, the volume ratio of the scandium-containing organic phase to the phosphoric acid solution is 3:1 to 1:

3.

4. The method according to any one of claims 1 to 3, characterized in that, The back-extraction temperature is 25~50℃; Preferably, the back-extraction time is 30-60 minutes; Preferably, the back-extraction is carried out under stirring; Preferably, the stirring speed during the back-extraction is 100~300 rpm.

5. The method according to any one of claims 1 to 4, characterized in that, The alkaline precipitation includes: adjusting the pH of the first scandium-containing solution to 7-11 using ammonia water; Preferably, the temperature of the alkali precipitation is 50~80℃; Preferably, the reaction time for alkali precipitation is 1-3 hours; Preferably, the method further includes: performing solid-liquid separation on the material after alkali precipitation, and washing the obtained solid phase; Preferably, the washing includes at least three washes.

6. The method according to any one of claims 1 to 5, characterized in that, The acid dissolution includes: mixing scandium hydroxide precipitate with acid solution; Preferably, the acid solution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, or nitric acid; Preferably, the solid-liquid ratio of the scandium hydroxide precipitate to the acid solution is 1:(1~3)mg / L.

7. The method according to any one of claims 1 to 6, characterized in that, The pH of the second scandium-containing solution is 0-1; Preferably, the acid dissolution temperature is 30~60℃.

8. The method according to any one of claims 1 to 7, characterized in that, The oxalic acid precipitation treatment includes: a second scandium-containing solution reacting with oxalic acid to induce a precipitation reaction; Preferably, the mass ratio of oxalic acid to scandium in the second scandium-containing solution is (3~6):

1.

9. The method according to claim 8, characterized in that, The precipitation reaction is carried out at a temperature of 50~80℃; Preferably, the precipitation reaction takes 1 to 3 hours; Preferably, the method further includes washing the obtained precipitated solid phase between the oxalic acid precipitation treatment and calcination.

10. The method according to any one of claims 1 to 9, characterized in that, The calcination temperature is 800~1000℃; Preferably, the roasting time is 2-6 hours; Preferably, the roasting atmosphere includes an oxygen-containing atmosphere; Preferably, the purity of the high-purity scandium oxide is ≥99.95wt%.

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