Recycling process of rare earth scandium

Abstract

The invention belongs to the field of rare earth metallurgical metals, and provides a rare earth scandium recovery treatment process which comprises the following steps: carrying out acid leaching on scandium-containing waste residues to obtain acid leaching mother liquor; mixing ammonium sulfate, an acid solution and the acid leaching mother liquor to obtain ammonium scandium sulfate double salt coarse precipitate; and the ammonium scandium sulfate double salt coarse precipitate is subjected to acid pickling, metal impurities are removed, and a rare earth scandium product is obtained. Aiming at the problem that ammonium scandium sulfate as a soluble precipitate is not beneficial to high-efficiency recovery of scandium, the recovery treatment process provided by the invention uses ammonium sulfate and an acid solution for precipitation, can control the acidity in a reaction system and the corresponding relationship between ammonium ion concentration and ammonium scandium sulfate solubility, and can effectively improve the ammonium scandium sulfate precipitation rate to 99% or above; and impurities such as U, Th, Fe, Na and Cu can be effectively washed away, so that a rare earth scandium intermediate product with relatively high purity is prepared, and efficient recovery of scandium resources is realized.

Description

Technical Field

[0001] This invention belongs to the field of rare earth metallurgy technology and relates to a rare earth scandium recycling process. Background Technology

[0002] Scandium is a typical dispersed element with low crustal abundance, averaging only about 5 parts per million (ppm). Due to its unique geochemical properties, scandium is unlikely to be enriched into independent deposits during geological evolution, but rather tends to coexist with other metallic elements in various minerals. Currently, known scandium-bearing minerals mainly include industrial minerals containing uranium, aluminum, iron, chromium, nickel, zirconium, titanium, tungsten, beryllium, and rare earth elements (REEs), with scandium often existing as a by-product in these metallic minerals. Therefore, scandium is usually recycled as a by-product during the extraction and metallurgical processes of related metals. In recent years, with the expanding applications of scandium in high-end materials, solid electrolytes, lighting sources, and aerospace, its strategic value has become increasingly prominent, and the efficient recovery and utilization of scandium resources has become a research hotspot in the fields of metallurgy and materials science.

[0003] The technology for recovering scandium from ores such as uranium, zirconium, titanium, and tungsten has achieved some industrial application progress in several countries. However, due to the low scandium content in these ores and the fact that the recovery process is usually limited by the main metal extraction process, the overall recovery rate and economic viability of scandium often fail to meet the needs of large-scale industrial applications. In contrast, laterite nickel ore is considered one of the most promising scandium resources due to its relatively high scandium content (generally 50-600 g / t). With the rapid development of the global new energy industry, especially the widespread application of nickel resources in lithium-ion battery materials, the mining scale of laterite nickel ore is constantly expanding. In this process, scandium, as a by-product element in nickel ore, is also enriched. Therefore, achieving simultaneous scandium recovery during nickel smelting has significant resource utilization value.

[0004] In the hydrometallurgical process of laterite nickel ore, scandium typically enters the leaching solution system in the form of sulfate, which usually has relatively high solubility, making it difficult to achieve complete precipitation and recovery rates. For example, CN118600247A discloses a method and application for the resource-based recovery of scandium from scandium-containing waste residue containing radioactive elements. This method achieves selective scandium recovery by generating NH4Sc(SO4)3 precipitate. However, this method has significant process defects. The added ammonium bicarbonate rapidly releases a large amount of carbon dioxide gas, causing violent bubbling and even overflow of the reaction system, posing a safety hazard. Simultaneously, the addition of ammonium bicarbonate significantly increases the pH of the solution, thereby triggering the precipitation of other metal ions (such as Fe). 3+ Al 3+The co-precipitation phenomenon of scandium (etc.) reduces the precipitation selectivity and recovery rate of scandium, resulting in a total yield of <95%.

[0005] In summary, existing precipitation processes still suffer from problems such as low scandium precipitation rate, severe co-precipitation of impurities, and poor operational safety. Therefore, developing an effective and easy-to-operate method that can improve the precipitation rate and selectivity of scandium ammonium sulfate for efficient recovery of scandium resources has significant research value and engineering practical implications. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a rare earth scandium recovery process, including acid leaching of scandium-containing waste residue to obtain acid leaching mother liquor; mixing ammonium sulfate, an acid solution, and the acid leaching mother liquor to obtain a coarse precipitate of scandium ammonium sulfate double salt; and acid washing of the coarse precipitate of scandium ammonium sulfate double salt to remove metallic impurities, thereby obtaining a rare earth scandium product. Addressing the problem that scandium sulfate, as a soluble precipitate, is not conducive to the efficient recovery of scandium, the recovery process of this invention uses ammonium sulfate and an acid solution for precipitation. This allows for control of the relationship between acidity and ammonium ion concentration and the solubility of scandium sulfate in the reaction system, effectively increasing the precipitation rate of scandium sulfate to over 99%, and effectively washing away impurities such as U, Th, Fe, Na, and Cu, thereby preparing a high-purity rare earth scandium intermediate product and achieving efficient recovery of scandium resources.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a rare earth scandium recycling process, comprising the following steps:

[0009] Scandium-containing waste residue is acid-leached to obtain acid leaching mother liquor;

[0010] Ammonium sulfate, acid solution, and the acid leaching mother liquor are mixed to obtain a crude precipitate of scandium ammonium sulfate double salt;

[0011] The crude precipitate of scandium sulfate double salt was acid-washed to remove metallic impurities, yielding rare earth scandium products.

[0012] The recycling process described in this invention uses ammonium sulfate and an acid solution for precipitation. The precipitate is scandium sulfate, whose solubility in solution can be significantly reduced by adjusting the acidity and ammonium ion concentration. For example, the concentration of Sc ions can be controlled to 100 mg / L or below, allowing for the full precipitation of high-concentration acid leaching mother liquor (e.g., above 20 g / L), thus achieving a Sc precipitation rate of over 99%. Impurities such as U, Th, Fe, Na, and Cu do not react with ammonium sulfate and remain in the solution, but some are entrained in the scandium sulfate precipitate. Therefore, subsequent acid washing of the scandium sulfate can both inhibit Sc dissolution and remove entrained impurities, achieving separation of Sc from U, Th, Fe, Na, Cu, and other impurities. This results in the preparation of a high-purity rare earth scandium intermediate product, achieving efficient scandium resource recovery. The solution described in this invention effectively solves the problem in existing technologies where the use of scandium sulfate as a soluble precipitate hinders efficient scandium recovery.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0014] As a preferred technical solution of the present invention, the scandium-containing waste residue includes crude scandium extract obtained by hydrometallurgical processing of laterite nickel ore, with a scandium content of 10wt%~20wt%, such as 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, or 20wt%, etc., and also contains at least one metallic impurity element selected from U, Th, Fe, Na, or Cu.

[0015] As a preferred technical solution of the present invention, in the acid leaching, the solid-liquid mass ratio of scandium-containing waste residue to acid solution is 1:(1~3), for example 1:1, 1.15:1, 1.3:1, 1.4:1, 1.5:1, 1.65:1, 1.8:1, 1.95:1, 2:1, 2.15:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.7:1, 2.8:1, 2.9:1 or 3:1, etc.

[0016] As a preferred embodiment of the present invention, the acid solution used in the acid leaching includes sulfuric acid.

[0017] Preferably, the sulfuric acid is a high-acidity sulfuric acid with a concentration ≥98%.

[0018] As a preferred technical solution of the present invention, the pH of the acid leaching is 0.5~1, for example 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0019] As a preferred technical solution of the present invention, the acid leaching temperature is 40~80℃, for example 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.

[0020] As a preferred technical solution of the present invention, the acid leaching is carried out under stirring for a time of 1 to 3 hours, such as 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3 hours.

[0021] As a preferred embodiment of the present invention, the concentration of scandium ions in the acid leaching mother liquor is ≥10g / L, such as 10g / L, 12g / L, 15g / L, 18g / L, 20g / L, 23g / L, 25g / L, 28g / L or 30g / L, preferably ≥20g / L.

[0022] As a preferred technical solution of the present invention, the mixing of ammonium sulfate and the acid leaching mother liquor is carried out at 40~80°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0023] As a preferred embodiment of the present invention, the mass ratio of the ammonium sulfate to the scandium in the acid leaching mother liquor is (2~5):1, for example, 2:1, 2.3:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, etc.

[0024] As a preferred embodiment of the present invention, after mixing ammonium sulfate, acid solution, and the acid leaching mother liquor, the concentration of ammonium ions in the reaction system is 0.1~6M, for example, 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.55M, 0.6M, 0.65M, 0.7M, 0.75M, 0.8M, 0.85M, 0.9M, 0.95M, 1M, 1.3M, 1.5M, 1.8M, 2M, 2.3M, 2.5M, 2.8M, 3M, 3.5M, 3.3M, 3.8M, 4M, 4.5M, 4.8M, 5M, 5.3M, 5.5M, 5.8M, or 6M, etc.

[0025] As a preferred embodiment of the present invention, the ammonium sulfate and the acid leaching mother liquor are first mixed, and then an acid solution is added.

[0026] Preferably, acid solution is added to maintain the acidity of the reaction system at 2-6M, such as 2M, 2.5M, 2.8M, 3M, 3.3M, 3.5M, 3.85M, 4M, 4.3M, 4.5M, 4.8M, 5M, 5.3M, 5.5M, 5.8M or 6M.

[0027] In this invention, the acidity and concentration of ammonium ions in the reaction system are further influenced, controlled, and adjusted by controlling the amount of ammonium sulfate and the amount of acid solution added. Figure 3 The diagram shows the relationship between the solubility of scandium sulfate and the acidity and ammonium ion concentration. By controlling the acidity and the concentration of ammonium ions, the concentration of scandium sulfate can be suppressed, and the concentration of dissolved scandium ions can be controlled at 100 mg / L or below, for example, at 87.40 mg / L or below, and further, for example, between 56.1 and 64 mg / L.

[0028] Preferably, after adding acid solution, the mixture is stirred for 1 to 3 hours, such as 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3 hours.

[0029] Preferably, the acid solution includes sulfuric acid.

[0030] As a preferred technical solution of the present invention, in the pickling, the solid-liquid mass ratio of the scandium ammonium sulfate double salt coarse precipitate to the washing solution is 1:(1~3), for example 1:1, 1:1.3, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8 or 1:3, etc.

[0031] Preferably, the pickling solution used includes sulfuric acid with a concentration of 4-8M, such as 4M, 4.3M, 4.5M, 4.8M, 5M, 5.3M, 5.5M, 5.8M, 6M, 6.3M, 6.5M, 6.8M, 7M, 7.2M, 7.5M, 7.8M or 8M.

[0032] Preferably, the pickling is repeated at least three times.

[0033] It should be noted that, due to space limitations and to avoid redundancy, this invention does not exhaustively list all point values ​​within the above numerical range, but it is not limited to the listed values ​​either; other unlisted values ​​within the above numerical range are also applicable.

[0034] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0035] The recycling process described in this invention uses ammonium sulfate and an acid solution for precipitation, which facilitates control of the acidity and ammonium ion concentration in the reaction system, thereby further controlling the solubility of scandium sulfate. This effectively increases the precipitation rate of scandium sulfate to over 99% and effectively removes impurities such as U, Th, Fe, Na, and Cu, thus preparing a high-purity rare earth scandium intermediate product. This achieves efficient recovery of scandium resources and effectively solves the problem in existing technologies where ammonium scandium sulfate, as a soluble precipitate, is not conducive to the efficient recovery of scandium. Attached Figure Description

[0036] Figure 1 This is a schematic flowchart of a rare earth scandium recycling process in Example 1.

[0037] Figure 2 This is the XRD pattern of the rare earth scandium product obtained in Example 1.

[0038] Figure 3 This is a graph showing the relationship between scandium concentration in the supernatant of the precipitate and acidity and ammonium ion concentration in the reaction system in one or more embodiments.

[0039] Figure 4A This is a graph showing the relationship between the solubility of scandium sulfate and the acidity of sulfuric acid in the reaction system in one or more embodiments.

[0040] Figure 4B This is a graph showing the relationship between the solubility of scandium ammonium sulfate and the concentration of ammonium ions in the reaction system in one or more embodiments. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0042] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0043] Example 1

[0044] This embodiment provides a rare earth scandium recycling process, such as... Figure 1 As shown, the recycling process includes the following steps:

[0045] S1. The crude scandium extract obtained by hydrometallurgical treatment of laterite nickel ore, with a scandium content of 15wt% and containing metallic impurities U, Th, Fe, Na and Cu, is treated as scandium-containing waste residue. Sulfuric acid is used as the acid solution, and the crude scandium extract is acid-leached with sulfuric acid under the conditions of solid-liquid mass ratio of 1:3, temperature of 60℃ and pH of 0.5 for 2 hours to obtain acid leaching mother liquor.

[0046] S2. At a temperature of 80℃, ammonium sulfate with a mass three times that of scandium was added to the acid leaching mother liquor, with an ammonium ion concentration of 1M. Then, concentrated sulfuric acid was added to maintain the acidity of the reaction system at 4M. The mixture was stirred for 2 hours to achieve preliminary impurity removal. The mixture was then filtered to obtain a coarse precipitate of scandium ammonium sulfate double salt. The scandium concentration in the supernatant of the precipitate was approximately 52 mg / L, and the scandium precipitation rate was calculated to be >99%.

[0047] S3. Using 6M sulfuric acid as the washing solution, the obtained scandium ammonium sulfate coarse precipitate was washed three times at a solid-liquid mass ratio of 1:2 to further remove the entrained metallic impurities U, Th, Fe, Na, and Cu. The impurity removal rate was calculated to be >99%, and rare earth scandium products were obtained.

[0048] Example 2

[0049] This embodiment provides a rare earth scandium recycling process, which includes the following steps:

[0050] S1. The crude scandium extract obtained by hydrometallurgical treatment of laterite nickel ore, with a scandium content of 15wt% and containing metallic impurities U, Th, Fe, Na and Cu, is treated as scandium-containing waste residue. Sulfuric acid is used as the acid solution, and the crude scandium extract is acid-leached with sulfuric acid under the conditions of solid-liquid mass ratio of 1:2, temperature of 50℃ and pH of 1, and stirred for 3 hours to obtain acid leaching mother liquor.

[0051] S2. At a temperature of 60℃, ammonium sulfate with a mass of 4 times that of scandium was added to the acid leaching mother liquor, with an ammonium ion concentration of 6M. Then, concentrated sulfuric acid was added to maintain the acidity of the reaction system at 2M. The mixture was stirred for 2 hours to achieve preliminary impurity removal. The mixture was then filtered to obtain a coarse precipitate of scandium ammonium sulfate double salt. The scandium concentration in the supernatant of the precipitate was approximately 87 mg / L, and the scandium precipitation rate was calculated to be >99%.

[0052] S3. Using 6M sulfuric acid as the washing solution, the obtained scandium ammonium sulfate coarse precipitate was washed three times at a solid-liquid mass ratio of 1:1 to further remove the entrained metallic impurities U, Th, Fe, Na, and Cu. The impurity removal rate was calculated to be >99%, and rare earth scandium product was obtained.

[0053] Example 3

[0054] This embodiment provides a rare earth scandium recycling process, which includes the following steps:

[0055] S1. The crude scandium extract obtained by hydrometallurgical treatment of laterite nickel ore, with a scandium content of 15wt% and containing metallic impurities U, Th, Fe, Na and Cu, is treated as scandium-containing waste residue. Sulfuric acid is used as the acid solution. Under the conditions of solid-liquid mass ratio of 1:3, temperature of 50℃ and pH of 0.8, the crude scandium extract is acid-leached with sulfuric acid and stirred for 3 hours to obtain acid leaching mother liquor.

[0056] S2. At a temperature of 70℃, ammonium sulfate with a mass of 1.5 times that of scandium was added to the acid leaching mother liquor, with an ammonium ion concentration of 0.1M. Then, concentrated sulfuric acid was added to maintain the acidity of the reaction system at 6M. The mixture was stirred for 2 hours to achieve preliminary impurity removal. The mixture was then filtered to obtain a coarse precipitate of scandium ammonium sulfate double salt. The scandium concentration in the supernatant of the precipitate was approximately 56 mg / L, and the scandium precipitation rate was calculated to be >99%.

[0057] S3. Using 6M sulfuric acid as the washing solution, the obtained scandium ammonium sulfate coarse precipitate was washed three times at a solid-liquid mass ratio of 1:3 to further remove the entrained metallic impurities U, Th, Fe, Na, and Cu. The impurity removal rate was calculated to be >99%, and rare earth scandium product was obtained.

[0058] Example 4

[0059] This embodiment provides a rare earth scandium recovery process. In step S2 of the recovery process, the amount of sulfuric acid added is adjusted so that the acidity in the reaction system is adjusted from 4M to 1M. Except for the above, the other conditions are exactly the same as in Example 1.

[0060] Example 5

[0061] This embodiment provides a rare earth scandium recovery process. In step S2 of the recovery process, the amount of sulfuric acid added is adjusted so that the acidity in the reaction system is adjusted from 4M to 2M. Except for the above, the other conditions are exactly the same as in Example 1.

[0062] Example 6

[0063] This embodiment provides a rare earth scandium recovery process. In step S2 of the recovery process, the amount of ammonium sulfate added is adjusted from 3 times the mass of scandium in the acid leaching mother liquor to 1 time. Except for the above, the other conditions are exactly the same as in Example 1.

[0064] Example 7

[0065] This embodiment provides a rare earth scandium recovery process. In step S2 of the recovery process, the amount of ammonium sulfate added is adjusted from 3 times the mass of scandium in the acid leaching mother liquor to 2 times. Except for the above, the other conditions are exactly the same as in Example 1.

[0066] Comparative Example 1

[0067] This comparative example provides a rare earth scandium recycling process. In step S2 of the recycling process, sulfuric acid is not added. Except for the above, the other conditions are exactly the same as in Example 1.

[0068] Comparative Example 2

[0069] This comparative example provides a rare earth scandium recycling process, wherein step S2 of the recycling process uses ammonium bicarbonate instead of ammonium sulfate of the same molar mass, and all other conditions are exactly the same as in Example 1.

[0070] Characterization and testing:

[0071] I. Figure 2 The image shown is the XRD pattern of the rare earth scandium product from Example 1, which confirms that its phase is scandium ammonium sulfate.

[0072] II. Similar to Examples 1 to 3, in Examples 4 to 11, as well as Comparative Examples 1 and 2, the scandium concentration in the supernatant of the crude precipitate of scandium ammonium sulfate double salt obtained by filtration in step S2 was tested, the scandium precipitation rate was calculated, and the impurity removal rate in step S3 was tested and calculated. The results are recorded in Table 1.

[0073] Table 1

[0074]

[0075] like Figure 4A as well as Figure 4B As shown, the scandium precipitation rate is negatively correlated with sulfuric acid acidity and ammonium ion concentration. Higher acidity and higher ammonium ion concentration inhibit the reverse precipitation reaction, resulting in a higher scandium precipitation rate. Conversely, excessively low acidity and low ammonium ion concentration promote the dissolution of scandium ammonium sulfate, leading to a low scandium precipitation rate. (Referring to Table 1 and...) Figure 3 It can be seen that replacing ammonium sulfate with ammonium bicarbonate not only leads to a decrease in scandium precipitation rate because it cannot provide sulfate ions, but also poses a risk of reactor failure during the production process due to the large amount of CO2 generated during the reaction. In addition, ammonium bicarbonate is an alkaline salt, and the pH of the solution increases during the reaction process, which can easily cause impurities such as U and Th to precipitate out as hydroxides, resulting in a decrease in the impurity removal rate.

[0076] In summary, the recycling process described in this invention uses ammonium sulfate and an acid solution for precipitation, which facilitates control of the acidity and ammonium ion concentration in the reaction system, thereby further controlling the solubility of scandium sulfate. This effectively increases the precipitation rate of scandium sulfate to over 99% and effectively removes impurities such as U, Th, Fe, Na, and Cu, thus producing a high-purity rare earth scandium intermediate product. This achieves efficient recovery of scandium resources and effectively solves the problem in existing technologies where ammonium sulfate, as a soluble precipitate, is not conducive to the efficient recovery of scandium.

[0077] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A rare earth scandium recycling process, characterized in that, Includes the following steps: Scandium-containing waste residue is acid-leached to obtain acid leaching mother liquor; Ammonium sulfate, acid solution, and the acid leaching mother liquor are mixed to obtain a crude precipitate of scandium ammonium sulfate double salt; The crude precipitate of scandium sulfate double salt was acid-washed to remove metallic impurities, yielding rare earth scandium products.

2. The rare earth scandium recycling process according to claim 1, characterized in that, The scandium-containing waste residue includes crude scandium extract obtained from laterite nickel ore hydrometallurgy, with a scandium content of 10wt%~20wt%, and also contains at least one metallic impurity element selected from U, Th, Fe, Na or Cu.

3. The rare earth scandium recycling process according to claim 1 or 2, characterized in that, The In acid leaching, the solid-liquid mass ratio of scandium-containing waste residue to acid solution is 1:(1~3); Preferably, the acid solution used in the acid leaching includes sulfuric acid.

4. The rare earth scandium recycling process according to any one of claims 1-3, characterized in that, The pH of the acid leaching is 0.5~1.

5. The rare earth scandium recycling process according to any one of claims 1-4, characterized in that, The acid leaching temperature is 40~80℃.

6. The rare earth scandium recycling process according to any one of claims 1-5, characterized in that, The acid leaching is carried out under stirring for 1 to 3 hours.

7. The rare earth scandium recycling process according to any one of claims 1-6, characterized in that, The process of mixing ammonium sulfate with the acid leaching mother liquor is carried out at 40-80°C.

8. The rare earth scandium recycling process according to any one of claims 1-7, characterized in that, The mass ratio of the ammonium sulfate to the scandium in the acid leaching mother liquor is (2~5):1; Preferably, after mixing ammonium sulfate, acid solution, and the acid leaching mother liquor, the concentration of ammonium ions in the reaction system is 0.1~6M.

9. The rare earth scandium recycling process according to any one of claims 1-8, characterized in that, The ammonium sulfate is first mixed with the acid leaching mother liquor, and then acid solution is added to supplement it; Preferably, acid solution is added to maintain the acidity of the reaction system at 2-6 M; Preferably, after adding the acid solution, the mixture is stirred for 1 to 3 hours; Preferably, the acid solution includes sulfuric acid.

10. The rare earth scandium recycling process according to any one of claims 1-9, characterized in that, In the pickling process, the solid-liquid mass ratio of the scandium ammonium sulfate double salt coarse precipitate to the washing solution is 1:(1~3); Preferably, the pickling solution used includes sulfuric acid with a concentration of 4-8M; Preferably, the pickling is repeated at least three times.

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