A method for preparing scandium oxyhydroxide using an acidic scandium-containing solution

Abstract

This invention provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The method includes the following steps: subjecting the acidic scandium-containing solution to a first-stage alkaline precipitation with a first alkaline precipitant to obtain a first-stage alkaline precipitate; subjecting the first-stage alkaline precipitate to a second alkaline precipitant and solid-liquid separation to obtain a second-stage alkaline precipitate and a second-stage alkaline precipitate product; subjecting the second-stage alkaline precipitate to a third-stage alkaline precipitation, aging, and solid-liquid separation with a third alkaline precipitant to obtain scandium hydroxyl oxide; and washing the obtained scandium hydroxyl oxide to obtain final low-impurity scandium hydroxyl oxide. The method of this invention can directly prepare scandium hydroxyl oxide using an acidic scandium-containing solution. Compared with the preparation of other scandium intermediates, it avoids the formation of soluble scandium salts and difficult-to-filter scandium hydroxide, thus directly preparing scandium intermediates with excellent filtration performance and easy processing, ensuring a very high scandium recovery rate, and shortening the production process of scandium intermediates.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology and relates to a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Background Technology

[0002] Scandium, a rare earth metal element, has wide applications in the lighting industry, alloy industry, ceramic materials, and catalytic materials. Currently, there are many existing technologies for recovering and extracting scandium oxide from various scandium-containing raw materials and wastes. Common raw materials or wastes for scandium extraction include scandium-containing ores, red mud, titanium dioxide waste acid, zirconium oxychloride waste acid, chlorinated flue dust, and slag from smelting tungsten, manganese, and ferromanganese. The basic methods for scandium extraction involve first transferring scandium to a solution through a leaching process, then concentrating and enriching the scandium in the solution and removing impurities through an extraction process. Subsequently, scandium is precipitated as scandium oxalate in solid form. Finally, the scandium-rich solid intermediate is further processed and purified to prepare scandium oxide.

[0003] Commonly used scandium precipitation processes include oxalate precipitation, hydroxide precipitation, sulfate double salt precipitation, oxide precipitation, and selective redox methods. For example, CN103361486A discloses a method for extracting high-purity scandium oxide and titanium from waste acid containing scandium and titanium. This method uses extraction to separate titanium from waste acid containing scandium and titanium, and uses double salt and alkali conversion to precipitate scandium hydroxide. However, in the existing technology, a certain amount of impurity ions are introduced during the precipitation reaction using precipitants. Furthermore, the mainstream processes for preparing scandium intermediates currently suffer from complex processes, low precipitation rates, and high costs.

[0004] Based on the above research, there is a need to provide a method for preparing scandium hydroxyl oxide. This method can directly prepare easily processed scandium intermediates, ensure a very high scandium recovery rate, shorten the production process of scandium intermediates, and reduce the processing cost of scandium products throughout the entire process. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. This method can directly prepare scandium hydroxyl oxide by using an acidic scandium-containing solution. Compared with the preparation of other scandium intermediates, it avoids the formation of soluble scandium salts and difficult-to-filter scandium hydroxide, and can directly prepare scandium intermediates with excellent filtration performance and easy processing. It ensures a very high scandium recovery rate, shortens the production process of scandium intermediates, reduces the processing cost of scandium products throughout the entire process, improves economic benefits, and can be widely promoted and applied.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution, the method comprising the following steps:

[0008] (1) Mix the acidic scandium-containing solution with the first alkaline precipitant to carry out the first stage of alkaline precipitation, and obtain a first alkaline precipitate;

[0009] (2) Mix the first alkaline precipitation liquid and the second alkaline precipitant described in step (1) to carry out the second stage of alkaline precipitation. After the second stage of alkaline precipitation is completed, perform solid-liquid separation to obtain the second alkaline precipitation liquid and the second alkaline precipitation product.

[0010] (3) The two-stage alkaline precipitation product described in step (2) is mixed with a third alkaline precipitant to carry out a third-stage alkaline precipitation. After the third-stage alkaline precipitation is completed, aging, solid-liquid separation and washing are carried out to obtain scandium hydroxyoxide.

[0011] The final pH of the third stage alkali precipitation in step (3) is greater than the final pH of the second stage alkali precipitation in step (2) and the final pH of the first stage alkali precipitation in step (1).

[0012] The temperature of the third stage alkali precipitation in step (3) is greater than or equal to the temperature of the second stage alkali precipitation in step (2) and the temperature of the first stage alkali precipitation in step (1).

[0013] This invention uses an acidic scandium-containing solution as the raw material to directly prepare scandium hydroxylate, an intermediate with excellent filtration performance and easy acid solubility, avoiding the extraction process and the preparation of soluble scandium salts. Furthermore, this invention prepares scandium hydroxylate through a three-stage alkaline precipitation process. In the first stage, no solid is produced, resulting in an alkaline precipitate. This step neutralizes the acid-base relationship of the system, altering the original solution's environment. In the second stage, solid precipitates, and the solid obtained in the second stage undergoes a third stage of alkaline precipitation, further transforming the precipitated solid phase. Finally, after the third stage of alkaline leaching and before solid-liquid separation, aging is performed to stabilize the synthesized phase. After aging, solid-liquid separation washes away impurities introduced during the alkaline precipitation process, yielding the final low-impurity scandium hydroxylate.

[0014] Preferably, the pH of the first stage of alkaline precipitation in step (1) is 0.1~2, for example, it can be 0.1, 0.5, 1, 1.5 or 2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] In this invention, the pH of the first-stage alkaline precipitation is preferably within a specific range. If the pH of the first-stage alkaline precipitation is too low, the conditions for changing the solution system cannot be met, and entering the second-stage alkaline precipitation will cause the solution volume to expand, the Sc concentration to decrease, and indirectly affect the recovery rate. If the pH of the first-stage alkaline precipitation is too high, a solid phase will be generated too quickly under high alkalinity conditions, resulting in a colloidal substance with smaller particles and extremely poor filtration performance. This phase is different from the phase generated under the second-stage alkaline precipitation conditions.

[0016] Preferably, the temperature of the first stage of alkali precipitation in step (1) is 25~50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the rotation speed of the first stage of alkali precipitation in step (1) is 150~300 r / min, for example, it can be 150 r / min, 200 r / min, 250 r / min or 300 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the mixing of the acidic scandium-containing solution with the first alkaline precipitant in step (1) includes adding the first alkaline precipitant to the acidic scandium-containing solution. The rate at which the first alkaline precipitant is added to the acidic scandium-containing solution in step (1) is 0.5 to 1.5 L / h, for example, it can be 0.5 L / h, 0.8 L / h, 1 L / h, 1.2 L / h or 1.5 L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, in step (1), the first alkaline precipitant includes 10-12 mol / L liquid alkali, such as 10 mol / L, 10.5 mol / L, 11 mol / L, 11.5 mol / L or 12 mol / L, or 13-15 mol / L ammonia, such as 13 mol / L, 13.5 mol / L, 14 mol / L, 14.5 mol / L or 15 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, after the first stage of alkaline precipitation in step (1) reaches the endpoint pH, if there is no change in pH within 0.4~0.6h (for example, it can be 0.4h, 0.45h, 0.5h, 0.55h or 0.6h), step (2) continues.

[0021] Preferably, the acid in the acidic scandium-containing solution in step (1) includes sulfuric acid and hydrochloric acid.

[0022] Preferably, in the acidic scandium-containing solution of step (1), the concentration of sulfate ions is 100~200 g / L, for example, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L or 200 g / L; the concentration of chloride ions is 50~100 g / L, for example, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L; the concentration of hydrogen ions is 1~4 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L or 4 mol / L; and the concentration of scandium ions is 3~15 g / L, for example, 3 g / L, 6 g / L, 9 g / L, 12 g / L or 15 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the impurity elements in the acidic scandium-containing solution in step (1) include any one or a combination of at least two of nickel, copper, iron, sodium, calcium, zirconium, titanium, silicon, aluminum, or magnesium.

[0024] Preferably, the total content of impurity elements in the acidic scandium-containing solution in step (1) is 10~500 mg / L, for example, it can be 10 mg / L, 100 mg / L, 250 mg / L or 500 mg / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pH of the second stage of alkaline precipitation in step (2) is 4 to 5, for example, it can be 4, 4.2, 4.4, 4.6, 4.8 or 5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] If the pH of the second-stage alkaline precipitation is too low, the scandium element cannot be completely converted into an intermediate solid phase; if the pH of the second-stage alkaline precipitation is too high, some impurity elements will precipitate.

[0027] Preferably, the temperature of the second stage of alkali precipitation in step (2) is 50~80℃, for example, it can be 50℃, 60℃, 70℃ or 80℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the rotation speed of the second stage alkali precipitation in step (2) is 150~300 r / min, for example, it can be 150 r / min, 200 r / min, 250 r / min or 300 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, step (2) of mixing the first alkaline precipitation solution and the second alkaline precipitant described in step (1) includes adding the second alkaline precipitant to the first alkaline precipitation solution. The rate at which the second alkaline precipitant is added to the first alkaline precipitation solution is 0.3~0.8 L / h, for example, it can be 0.3 L / h, 0.5 L / h, 0.7 L / h or 0.8 L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, in step (2), the second alkaline precipitant includes any one or a combination of at least two of liquid alkali, ammonia, sodium carbonate solution or ammonium bicarbonate solution.

[0031] Preferably, the second alkaline precipitant in step (2) includes any one or a combination of at least two of the following: 1-5 mol / L (e.g., 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L) of liquid alkali, 1-5 mol / L (e.g., 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L) of ammonia water, 3-8 wt% (e.g., 3 wt%, 5 wt%, 6 wt% or 8 wt%) of sodium carbonate solution, or 3-8 wt% (e.g., 3 wt%, 5 wt%, 6 wt% or 8 wt%) of ammonium bicarbonate solution.

[0032] Preferably, after the second stage of alkaline precipitation in step (2) reaches the endpoint pH, solid-liquid separation is performed if the pH does not change within 0.4~0.6h (for example, it can be 0.4h, 0.45h, 0.5h, 0.55h or 0.6h).

[0033] Preferably, the pH of the third stage alkaline precipitation in step (3) is 8 to 12, for example, it can be 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] If the pH of the third-stage alkaline precipitation in this invention is too low, the intermediate phase cannot be completely transformed; if the pH of the third-stage alkaline precipitation is too high, the alkaline precipitant will be excessively wasted.

[0035] Preferably, the temperature of the third stage alkali precipitation in step (3) is 80~90℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the temperature of the third stage alkali precipitation in step (3) is greater than the temperature of the second stage alkali precipitation in step (2) and the temperature of the first stage alkali precipitation in step (1).

[0037] The present invention preferably uses a third-stage alkaline precipitation temperature that is greater than the second-stage alkaline precipitation temperature that is greater than the first-stage alkaline precipitation temperature, which can further improve the alkaline precipitation effect.

[0038] Preferably, the rotation speed of the third stage alkali precipitation in step (3) is 50~150 r / min, for example, it can be 50 r / min, 80 r / min, 100 r / min, 120 r / min or 150 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, step (3) of mixing the second-stage alkaline precipitation product of step (2) with the third alkaline precipitant includes adding the third alkaline precipitant to the second-stage alkaline precipitation product. The rate at which the third alkaline precipitant is added to the second-stage alkaline precipitation product is 0.03~0.08 L / h, for example, it can be 0.03 L / h, 0.04 L / h, 0.05 L / h, 0.06 L / h or 0.08 L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the third alkaline precipitant in step (3) includes any one or a combination of at least two of liquid alkali, ammonia, sodium carbonate solution or ammonium bicarbonate solution.

[0041] Preferably, the third alkaline precipitant in step (3) includes 0.5~1 mol / L liquid alkali, such as 0.5 mol / L, 0.7 mol / L, 0.9 mol / L or 1 mol / L; or 1~5 mol / L ammonia, such as 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, after the third stage of alkaline precipitation in step (3) reaches the endpoint pH, solid-liquid separation is performed if the pH does not change within 0.4~0.6h (for example, it can be 0.4h, 0.45h, 0.5h, 0.55h or 0.6h).

[0043] Preferably, the aging temperature in step (3) is 80~90℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the aging time in step (3) is 2 to 6 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the aging speed in step (3) is 20~80 r / min, for example, it can be 20 r / min, 40 r / min, 60 r / min or 80 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the pH of the aging process in step (3) is 8 to 12, for example, it can be 8, 9, 10, 11 or 12, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the solid-liquid mass ratio of the washing in step (3) is 1:(3~10), for example, it can be 1:3, 1:5, 1:7, 1:9 or 1:10, the temperature is 40℃~60℃, for example, it can be 40℃, 45℃, 50℃, 55℃ or 60℃, and the number of times is 3 to 5, for example, it can be 3 times, 4 times or 5 times.

[0048] Preferably, the detergent used in step (3) includes pure water.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention shortens the process of producing scandium intermediates and can directly prepare scandium hydroxy oxide, which has excellent filtration performance and is easy to process, avoiding the extraction process and the preparation of soluble scandium salts.

[0051] (2) The preparation process of this invention is simple, the scandium recovery rate is extremely high, the production cost is low, and the comprehensive utilization and high added value utilization of scandium resources in complex acidic scandium solutions are realized, which can be industrialized on a large scale. Attached Figure Description

[0052] Figure 1 This is a flowchart of the method described in Embodiment 1 of the present invention.

[0053] Figure 2 The image shows the XRD pattern of scandium hydroxyoxide obtained in Example 1 of this invention. Detailed Implementation

[0054] 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.

[0055] The elemental contents of the acidic scandium-containing solutions described in the following examples and comparative examples are shown in Table 1:

[0056] Table 1

[0057]

[0058] Example 1

[0059] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The flowchart of the method is shown below. Figure 1 As shown, it includes the following steps:

[0060] (1) Add 10 mol / L liquid alkali to 10 L of acidic scandium-containing solution at a rate of 1 L / h to carry out the first stage of alkali precipitation. The temperature of the first stage of alkali precipitation is 40 °C, the rotation speed is 200 r / min, the endpoint pH is 0.5, and observe for 0.5 h after the pH reaches the target endpoint. If there is no change in pH, proceed to the next step.

[0061] (2) Add 1.5 mol / L of liquid alkali to the first alkaline precipitation solution obtained in step (1) at a rate of 0.5 L / h, and carry out the second stage alkaline precipitation at 60℃ and 150 r / min. The endpoint of the second stage alkaline precipitation is pH=4.5. At this time, a white solid precipitates in the solution. After the pH reaches the target, observe for 0.5 h without any change, and then carry out solid-liquid separation to obtain the second alkaline precipitation solution and the second alkaline precipitation product.

[0062] (3) Add 1.5 mol / L liquid alkali to the two-stage alkali precipitation product obtained in step (2) at a rate of 0.05 L / h, and carry out the third stage of alkali precipitation at 80℃ and 50 r / min. The endpoint of the third stage of alkali precipitation is pH=10. After the pH reaches the target, observe for 0.5 h without any change, and then carry out the fourth stage of aging treatment. The aging treatment temperature is maintained at 80℃, the aging time is 2 h, the rotation speed is maintained at 50 r / min, and the endpoint pH is maintained at 10. After the aging time is reached, perform solid-liquid separation to obtain solid scandium hydroxyoxide. The XRD pattern of the scandium hydroxyoxide is shown in the figure. Figure 2 As shown, it exhibits the characteristic diffraction peaks of scandium hydroxyoxide.

[0063] Example 2

[0064] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution, the method comprising the following steps:

[0065] (1) Add 12 mol / L liquid alkali to 10 L of acidic scandium-containing solution at a rate of 1.5 L / h to carry out the first stage of alkali precipitation. The temperature of the first stage of alkali precipitation is 25 °C, the rotation speed is 300 r / min, the endpoint pH is 0.1, and observe for 0.6 h after the pH reaches the target endpoint. If there is no change in pH, proceed to the next step.

[0066] (2) Add 5 mol / L liquid alkali to the first alkaline precipitation solution obtained in step (1) at a rate of 0.8 L / h, and carry out the second stage alkaline precipitation at 50℃ and 300 r / min. The endpoint of the second stage alkaline precipitation is pH=4. At this time, a white solid precipitates in the solution. After the pH reaches the target, observe for 0.4 h without any change, and then carry out solid-liquid separation to obtain the second alkaline precipitation solution and the second alkaline precipitation product.

[0067] (3) Add 0.5 mol / L liquid alkali to the two-stage alkali precipitation product obtained in step (2) at a rate of 0.08 L / h, and carry out the third stage alkali precipitation at 80℃ and 150 r / min. The endpoint of the third stage alkali precipitation is pH=8. After the pH reaches the target, observe for 0.6 h without any change, and then carry out the fourth stage aging treatment. The aging treatment temperature is maintained at 80℃, the aging time is 4 h, the rotation speed is maintained at 80 r / min, and the endpoint pH is maintained at 8. After the aging time is reached, solid-liquid separation is carried out to obtain solid scandium hydroxyoxide.

[0068] Example 3

[0069] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution, the method comprising the following steps:

[0070] (1) Add 15 mol / L ammonia water to 10L acidic scandium-containing solution at a rate of 0.5L / h to carry out the first stage of alkaline precipitation. The temperature of the first stage of alkaline precipitation is 50℃, the rotation speed is 150r / min, the endpoint pH=2, and observe for 0.4h after the pH reaches the target endpoint. If there is no change in pH, proceed to the next step.

[0071] (2) Add 2 mol / L ammonia water to the alkaline precipitation solution obtained in step (1) at a rate of 0.3 L / h, and carry out the second stage of alkaline precipitation at 80℃ and 150 r / min. The endpoint of the second stage of alkaline precipitation is pH=5. At this time, a white solid precipitates in the solution. After the pH reaches the target, observe for 0.6 h without any change, and then carry out solid-liquid separation to obtain the second stage of alkaline precipitation solution and the second stage of alkaline precipitation product.

[0072] (3) Add 1 mol / L ammonia water to the two-stage alkaline precipitation product obtained in step (2) at a rate of 0.03 L / h, and carry out the third stage alkaline precipitation at 90℃ and 50 r / min. The endpoint pH of the third stage alkaline precipitation is 10. After the pH reaches the target, observe for 0.4 h without any change, and then carry out the fourth stage aging treatment. The aging treatment temperature is maintained at 90℃, the aging time is 6 h, the rotation speed is maintained at 20 r / min, and the endpoint pH is maintained at 12. After the aging time is reached, solid-liquid separation is carried out to obtain solid scandium hydroxyoxide.

[0073] Example 4

[0074] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the first stage alkaline precipitation in step (1) being 0.05, the method is the same as in Example 1.

[0075] Example 5

[0076] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the first stage alkaline precipitation in step (1) being 2.5, the method is the same as in Example 1.

[0077] Example 6

[0078] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the second stage alkaline precipitation in step (2) being 3.5, the method is the same as in Example 1.

[0079] Example 7

[0080] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the second stage alkaline precipitation in step (2) being 5.5, the method is the same as in Example 1.

[0081] Example 8

[0082] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the third-stage alkaline precipitation in step (3) being 7.5, the method is the same as in Example 1.

[0083] Example 9

[0084] This embodiment provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. Except for the endpoint pH of the third-stage alkaline precipitation in step (3) being 12.5, the method is the same as in Example 1.

[0085] Comparative Example 1

[0086] This comparative example provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The method is the same as in Example 1 except that the first stage of alkaline precipitation in step (1) is not performed.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The method is the same as in Example 1 except that the second stage alkaline precipitation in step (2) is not performed.

[0089] Comparative Example 3

[0090] This comparative example provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The method is the same as in Example 1 except that the third-stage alkaline precipitation described in step (3) is not performed.

[0091] Comparative Example 4

[0092] This comparative example provides a method for preparing scandium hydroxyl oxide using an acidic scandium-containing solution. The method is the same as that in Example 1 except that the fourth stage of aging treatment described in step (3) is not performed.

[0093] The Sc concentration in the alkali precipitation solution obtained in the second stage of the above embodiments and comparative examples, the Sc concentration in the solution obtained in the fourth stage of aging treatment, the Sc recovery rate of the second stage of alkali precipitation, and the Sc recovery rate after the fourth stage of aging treatment are shown in Table 2.

[0094] Table 2

[0095]

[0096] The elemental contents of scandium hydroxyoxide obtained in the above examples and comparative examples are shown in Table 3.

[0097] Table 3

[0098]

[0099] As can be seen from Table 2-3 above:

[0100] As shown in Examples 1 and Comparative Examples 1-4, the present invention employs a three-stage alkaline precipitation process. The first stage of alkaline precipitation yields no precipitation, the second stage produces a solid precipitate, and the third stage involves aging. This four-stage treatment not only achieves a high scandium recovery rate but also results in a low impurity content in the scandium hydroxyoxide product. Without any one of the four stages, it is impossible to simultaneously obtain both a high recovery rate and low impurity content in scandium hydroxyoxide. As shown in Examples 1 and Examples 4-9, if the pH of the first-stage alkaline precipitation is too low, it indirectly affects the recovery rate; if the pH is too high, it produces a colloidal substance with even smaller particles and extremely poor filtration performance. If the pH of the second-stage alkaline precipitation is too low, it cannot completely convert the scandium element into an intermediate solid phase; if the pH is too high, some impurity elements precipitate. If the pH of the third-stage alkaline precipitation is too low, the intermediate phase cannot be completely converted; if the pH is too high, the alkaline precipitant is excessively wasted, and additional impurities may be introduced. Therefore, the endpoint pH of the first stage alkaline precipitation, the endpoint pH of the second stage alkaline precipitation, and the endpoint pH of the third stage alkaline precipitation are preferably within a specific range, which can further improve the alkaline precipitation effect and reduce the impurity content in the product.

[0101] 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 scandium hydroxyl oxide using an acidic scandium-containing solution, characterized in that, The method includes the following steps: (1) Mix the acidic scandium-containing solution with the first alkaline precipitant to carry out the first stage of alkaline precipitation, and obtain a first alkaline precipitate; (2) Mix the first alkaline precipitation liquid and the second alkaline precipitant described in step (1) to carry out the second stage of alkaline precipitation. After the second stage of alkaline precipitation is completed, perform solid-liquid separation to obtain the second alkaline precipitation liquid and the second alkaline precipitation product. (3) The two-stage alkaline precipitation product described in step (2) is mixed with a third alkaline precipitant to carry out a third-stage alkaline precipitation. After the third-stage alkaline precipitation is completed, aging, solid-liquid separation and washing are carried out to obtain scandium hydroxyoxide. The final pH of the third stage alkali precipitation in step (3) is greater than the final pH of the second stage alkali precipitation in step (2) and the final pH of the first stage alkali precipitation in step (1). The temperature of the third stage alkali precipitation in step (3) is greater than or equal to the temperature of the second stage alkali precipitation in step (2) and the temperature of the first stage alkali precipitation in step (1).

2. The method according to claim 1, characterized in that, Step (1) The pH of the first stage of alkaline precipitation is 0.1~2; Preferably, the temperature of the first stage of alkali precipitation in step (1) is 25~50℃; Preferably, the rotation speed of the alkali precipitation in the first stage of step (1) is 150~300 r / min.

3. The method according to claim 1 or 2, characterized in that, Step (1) The first alkaline precipitant is added to the acidic scandium-containing solution at a rate of 0.5~1.5 L / h; Preferably, in step (1), the first alkaline precipitant comprises 10-12 mol / L liquid alkali or 13-15 mol / L ammonia water; Preferably, after the first stage of alkaline precipitation in step (1) reaches the endpoint pH, if there is no change in pH within 0.4~0.6h, step (2) continues.

4. The method according to claim 1 or 2, characterized in that, The acid in the acidic scandium-containing solution in step (1) includes sulfuric acid and hydrochloric acid; Preferably, in the acidic scandium-containing solution in step (1), the concentration of sulfate ions is 100~200g / L, the concentration of chloride ions is 50~100g / L, the concentration of hydrogen ions is 1~4mol / L, and the concentration of scandium ions is 3~15g / L. Preferably, the impurity elements in the acidic scandium-containing solution in step (1) include any one or a combination of at least two of nickel, copper, iron, sodium, calcium, zirconium, titanium, silicon, aluminum, or magnesium; Preferably, the total content of impurity elements in the acidic scandium-containing solution in step (1) is 10~500 mg / L.

5. The method according to claim 1 or 2, characterized in that, In step (2), the pH of the second stage of alkaline precipitation is 4-5; Preferably, the temperature of the second stage of alkali precipitation in step (2) is 50~80℃; Preferably, the rotation speed of the second stage of alkali precipitation in step (2) is 150~300 r / min.

6. The method according to claim 1 or 2, characterized in that, In step (2), the second alkaline precipitant is added to the alkaline precipitation solution at a rate of 0.3~0.8 L / h. Preferably, in step (2), the second alkaline precipitant includes any one or a combination of at least two of liquid alkali, ammonia, sodium carbonate solution or ammonium bicarbonate solution; Preferably, in step (2), the second alkaline precipitant includes any one or a combination of at least two of the following: 1-5 mol / L liquid alkali, 1-5 mol / L ammonia, 3-8 wt% sodium carbonate solution, or 3-8 wt% ammonium bicarbonate solution. Preferably, after the second stage of alkaline precipitation in step (2) reaches the endpoint pH, solid-liquid separation is carried out if there is no change in pH within 0.4~0.6h.

7. The method according to claim 1 or 2, characterized in that, The pH of the third-stage alkaline precipitation in step (3) is 8-12; Preferably, the temperature of the third stage of alkali precipitation in step (3) is 80~90℃.

8. The method according to claim 1 or 2, characterized in that, The temperature of the third stage alkali precipitation in step (3) is greater than the temperature of the second stage alkali precipitation in step (2) and the temperature of the first stage alkali precipitation in step (1). Preferably, the rotation speed of the third stage alkali precipitation in step (3) is 50~150 r / min.

9. The method according to claim 1 or 2, characterized in that, In step (3), the rate at which the third alkaline precipitant is added to the second-stage alkaline precipitation product is 0.03~0.08 L / h; Preferably, the third alkaline precipitant in step (3) includes any one or a combination of at least two of liquid alkali, ammonia, sodium carbonate solution or ammonium bicarbonate solution; Preferably, the third alkaline precipitant in step (3) includes 0.5~1 mol / L liquid alkali or 1~5 mol / L ammonia water; Preferably, after the third stage of alkaline precipitation in step (3) reaches the endpoint pH, solid-liquid separation is carried out if there is no change in pH within 0.4~0.6h.

10. The method according to claim 1 or 2, characterized in that, The aging temperature in step (3) is 80~90℃; Preferably, the aging time in step (3) is 2-6 hours; Preferably, the aging speed in step (3) is 20~80 r / min; Preferably, the pH of the aging process in step (3) is 8-12; Preferably, the solid-liquid mass ratio of the washing process in step (3) is 1:(3~10), the temperature is 40℃~60℃, and the number of washes is 3~5 times; Preferably, the detergent used in step (3) includes pure water.

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