Composite extractant, method for scandium extraction, and scandium oxide product

Abstract

A composite extractant for scandium extraction includes: a first extractant comprising at least one selected from an acidic extractant, a neutral extractant, and an alkaline extractant; a second extractant comprising at least one selected from a ketone compound and an ester compound; and a diluent. The first extractant has an amount of 5-20wt% based on a total weight of the composite extractant, and the second extractant has an amount of 0.5-5wt% based on a total weight of the composite extractant.

Description

[0001] P 139010-19679

[0002] COMPOSITE EXTRACTANT, METHOD FOR SCANDIUM EXTRACTION, AND

[0003] SCANDIUM OXIDE PRODUCT

[0004] FIELD

[0005] The present disclosure relates to the technical field of hydrometallurgy, and more particularly to a composite extractant for scandium extraction, a method for scandium extraction, and a scandium oxide product.

[0006] BACKGROUND

[0007] Scandium is an important metal element widely used in aerospace, electronics industry, special materials and other fields, including aluminum-scandium alloy, new electric light source material, laser material, electronic material, catalytic industry, superconducting material, optical material, ceramic material and other high-level technology fields. Scandium (Sc) has a high content in earth crust, but there are few independent scandium deposits, and the scandium mainly exists in a form of associated minerals. Secondary resources for scandium extraction include a byproduct of uranium ore, a Bayan Obo tailing, a tungsten slag, and a titanium white waste acid solution, a laterite nickel ore acid leaching solution, a mixed nickel-cobalt hydroxide precipitate (MHP) acid leaching solution, a boiling chlorination smoke, a titanium-containing blast furnace slag, and a red mud.

[0008] In related arts, a main method for producing a scandium oxide product is extraction, i.e. an extractant is used to extract the scandium from the secondary resource aforementioned. However, during the scandium extraction using the existing extractant, it is prone to forming a third phase, resulting in difficult phase separation, and ultimately leading to the scandium oxide product produced with a high impurity content and a loss of extractant.

[0009] SUMMARY

[0010] Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

[0011] According to a first aspect of the present disclosure, a composite extractant for scandium extraction is provided. The composite extractant includes: a first extractant including at least one selected from an acidic extractant, a neutral extractant, and an alkaline extractant; a second extractant including at least one selected from a ketone compound and an ester compound; and a diluent; in which, the first extractant has an amount of 5-20wt% based on a total weight of the composite extractant, and the second extractant has an amount of 0.5-5wt% based on a total weight of the composite extractant. The composite extractant of the present disclosure includes at least two different components as effective extractants, in which the first extractant serves as a main extractant during the scandium extraction, and the second extractant serves as an auxiliary extractant during the scandium extraction. An addition of the second extractant in the composite extractant can effectively avoid a generation of a third phase, so that the composite extractant of the present disclosure has an enhanced scandium extraction performance and an improved repeatability. In addition, the composite extractant has advantages of a low pollution, a low toxicity and a low cost due to a low amount of the second extractant.

[0012] In some embodiments of the present disclosure, the acidic extractant is selected from a group including di-(2-ethylhexyl)phosphoric acid (P204), 2-ethylhexyl phosphoric acid mono-2- ethylhexyl ester (P507), di(l-methyl-heptyl) methyl phosphonate (P350), diisooctylphosphinic acid (C272), 8-hydroxyquinoline and acidic phosphine (C301), and bis(2,4,4-trimethylpentyl) monothiophosphonic acid (C302); and / or, the neutral extractant is selected from a group including tributyl phosphate (TBP), trialkyl phosphine oxide (TRPO), and trialkyl phosphine oxide (TOPO); and / or, the alkaline extractant is selected from a group including secondary carbon primary amine (N 1923) and trioctyldecylamine tertiary amine (N235). The acidic extractant, the neutral extractant, and the alkaline extractant provided in the embodiments of the present disclosure are accessible.

[0013] In some embodiments of the present disclosure, the ketone compound is selected from a group including hexanone, heptanone, and octanone. For example, the ketone compound is hexanone, which has a low toxicity, a low irritating odor, and a low cost. A low amount of the hexanone doping in the composite extractant can improve the scandium extraction performance and the repeatability of the composite extractant.

[0014] In some embodiments of the present disclosure, the ester compound is selected from a group including butyl acetate, butyl propionate, and butyl butyrate. For example, butyl acetate is selected as the second extractant doping in the composite extractant to improve the scandium extraction performance and the repeatability of the composite extractant.

[0015] In some embodiments of the present disclosure, the second extractant has an amount of 0.5-

[0016] 2wt% based on a total weight of the composite extractant. For example, the second extractant has an amount of 1.0 wt%. The scandium extraction performance of the composite extractant which meets the further condition may be further improved. In addition, the composite extractant which meets the further condition is environmentally friendly.

[0017] According to a second aspect of the present disclosure, a method for scandium extraction is provided. The method includes: mixing a scandium-containing acid solution with the composite extractant, according to the first aspect of the present disclosure, for extraction, and obtaining an extract solution after phase separation; adding a first alkali solution into the extract solution for back-extraction to obtain a scandium-rich slag; adding an acid solution into the scandium-rich slag for acid dissolution to obtain a scandium-rich aqueous solution; adding a second alkali solution into the scandium-rich aqueous solution for precipitation to obtain a scandium hydroxide; and performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product. With a usage of the composite extractant for extraction, the problem of generating the third phase during scandium extraction can be solved, and the phase separation is easier to operate, which achieved the scandium extraction from the scandium-containing acid solution with a simple process and a high scandium extraction rate, reducing a loss of extractant and lowing an extraction cost. Benefiting from the enhanced scandium extraction performance of the composite extractant, the scandium oxide product produced according to the method for scandium extraction of the present disclosure has a low impurity content and a high purity, which contributes to a high-value utilization of scandium.

[0018] In some embodiments of the present disclosure, the scandium-containing acid solution is selected from a group including titanium white waste acid solution, mixed nickel-cobalt hydroxide precipitate acid leaching solution and laterite nickel ore acid leaching solution; and / or, the scandium-containing acid solution includes a scandium with a concentration ranging from 10 to 10000 ppm. The method for scandium extraction of the present disclosure can extract the scandium from the scandium-containing acid solution in the high scandium extraction rate.

[0019] In some embodiments of the present disclosure, a volume ratio of the scandium-containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1; and / or, the extraction has an extraction temperature ranging from 20 to 60°C. It can be noted that the extraction temperature of the method of the present disclosure is relatively mild, which further simplifies the operation for scandium extraction.

[0020] In some embodiments of the present disclosure, the first alkali solution is selected from a group including sodium hydroxide solution, and potassium hydroxide solution; and / or, the first alkali solution has a concentration of 0.4 mol / L-2 mol / L; and / or, a volume ratio of the first alkali solution to the extract solution is in a range from 1 :3 to 3 : 1 ; and / or, the back-extraction has a back- extraction temperature ranging from 50 to 100°C. After the back-extraction, the scandium is enriched in the scandium-rich slag, the scandium-rich slag is obtained by solid-liquid separation, and the composite extractant is reused after oil-water separation.

[0021] In some embodiments of the present disclosure, the acid solution is selected from a group including sulfuric acid solution, hydrochloric acid solution and nitric acid solution; and / or, the acid solution has a concentration of 0.5mol / L -3mol / L. After the acid dissolution, scandium ion dissolves in the scandium-rich aqueous solution, and impurities may be removed.

[0022] In some embodiments of the present disclosure, the second alkali solution is selected from a group including sodium hydroxide solution and potassium hydroxide solution, and / or, the second alkali solution has a concentration of 0.4mol / L -2mol / L; and / or, a volume ratio of the second alkali solution to the scandium-rich aqueous solution is in a range from 1 :3 to 3: 1; and / or, the precipitation process has a precipitation temperature ranging from 10 to 40 °C.

[0023] In some embodiments of the present disclosure, the pyrolysis process has a pyrolysis temperature ranging from 400 to 900 °C, and / or, a pyrolysis duration ranging from 0.5 to 5.0 h. The scandium oxide product with the high purity is generated through a high-temperature pyrolysis of the scandium hydroxide.

[0024] According to a third aspect of the present disclosure, a method for scandium extraction is provided. The method includes: mixing a scandium-containing acid solution with the composite extractant, according to the first aspect of the present disclosure, and obtaining an extract solution after phase separation; and, adding a third alkali solution into the extract solution for back- extraction to obtain a scandium hydroxide; and, performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product. Benefiting from the enhanced scandium extraction performance of the composite extractant, the scandium hydroxide obtained after the back- extraction has a low impurity content and a high purity, the scandium oxide product can be thus obtained directly by performing the pyrolysis on the scandium hydroxide, which further simplifies the extraction process, and the scandium oxide product has a desirable purity.

[0025] In some embodiments of the present disclosure, the scandium-containing acid solution is selected from a group including titanium white waste acid solution and mixed nickel-cobalt hydroxide precipitate acid leaching solution; and / or, the scandium-containing acid solution including a scandium with a concentration ranging from 10 to 10000 ppm. The method for scandium extraction of the present disclosure can extract the scandium from the scandium- containing acid solution in the high scandium extraction rate.

[0026] In some embodiments of the present disclosure, a volume ratio of the scandium-containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1; and / or, the extraction has an extraction temperature ranging from 20 to 60°C. It can be noted that the extraction temperature of the method of the present disclosure is relatively mild, which further simplifies the operation for scandium extraction.

[0027] In some embodiments of the present disclosure, the third alkali solution is selected from a group including sodium hydroxide solution andpotassium hydroxide solution; and / or, the third alkali solution has a concentration of 0.4mol / L-2mol / L; and / or, a volume ratio of the third alkali solution to the extract solution is in a range from 1 :3 to 3 : 1 ; and / or, the back-extraction has a back- extraction temperature ranging from 50 to 100°C. After the back-extraction, the scandium is enriched in the scandium-rich slag, the scandium-rich slag is obtained by solid-liquid separation, and the composite extractant is reused after oil-water separation.

[0028] In some embodiments of the present disclosure, the pyrolysis process has a pyrolysis temperature ranging from 400 to 900 °C, and / or a pyrolysis duration ranging from 0.5 to 5.0 h. The scandium oxide product with the high purity is generated through a high-temperature pyrolysis of the scandium hydroxide.

[0029] According to a fourth aspect of the present disclosure, a scandium oxide product is provided. The scandium oxide product is prepared by the method according to the second aspect of the present disclosure, or by the method according to the third aspect of the present disclosure. The scandium oxide product has a low impurity content and a high purity.

[0030] It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and shall not be construed to limit the present disclosure.

[0031] DETAILED DESCRIPTION

[0032] Reference will now be made in detail to embodiments. The implementations set forth in the following description of the embodiments do not represent all implementations consistent with the present disclosure.

[0033] Terms used herein in embodiments of the present disclosure are only for the purpose of describing specific embodiments, but should not be construed to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, “a / an”, and “the” in singular forms are intended to include plural forms, unless clearly indicated in the context otherwise. It should also be understood that, the term “and / or” used herein represents and contains any or all possible combinations of one or more associated listed items.

[0034] When term “about” is used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

[0035] Term “range” disclosed in the present disclosure is defined in the form of a lower limit and an upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range defined in this way can be inclusive or exclusive, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60-110 and 80-120 are also obtained. In addition, if the listed minimum values are 1 and 2, and if the listed maximum values are 3, 4 and 5, the ranges of 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may be obtained. In the present disclosure, unless otherwise specified, the numerical range “a-b” means the abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range “0-5” means that all the real numbers between “0-5” have been listed, and “0-5” is only the abbreviated representation of these numerical combinations. In addition, when a parameter is an integer >2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] Composite extractant for scandium extraction

[0037] The embodiments of the present disclosure provides a composite extractant for scandium extraction. Compared with an extractant with an individual effective component, the composite extractant, with at least two types of extractants, in the embodiments of the present disclosure displays an enhanced scandium extraction performance and an improved repeatability during the scandium extraction.

[0038] In the embodiments of the present disclosure, the composite extractant includes a first extractant, a second extractant, and a diluent. The first extractant has an amount of 5-20wt% based on a total weight of the composite extractant, and the second extractant has an amount of 0.5-5wt% based on a total weight of the composite extractant. In an example, except for the first extractant and the second extractants, the rest in the composite extractant may be the diluent. The first extractant includes at least one selected from an acidic extractant, a neutral extractant, and an alkaline extractant. The second extractant includes at least one selected from a ketone compound and an ester compound. The ketone compound refers to a compound in which a carbonyl group (C=O, an organic functional group formed by connecting carbon atom and oxygen atom through a double bond) is connected to two alkyl groups (i.e. a hydrocarbon group formed by losing one hydrogen atom from an alkane molecule), and the ester compound refers to a compound with a general formula of R-COO-R’, where R can be a hydrocarbon group or a hydrogen atom, and R’ cannot be a hydrogen atom.

[0039] The composition extractant in the embodiments of the present disclosure includes the first extractant selected from common scandium extractants, such as the acidic extractant, the neutral extractant and the alkaline extractant, and the second extractant selected from the ketone compound and the ester compound. The addition of the second extractant in the composite can effectively avoid a generation of a third phase during extraction, which causes an enhanced scandium extraction performance and an improved repeatability of the composite extractant.

[0040] In some embodiments of the present disclosure, the amount of the first extractant is equal to or generally greater than that of the second extractant, in which, the amount of the first extractant is ranged from 5wt% to 20wt%, and the amount of the second extractant is ranged from 0.5wt% to 5wt%. For example, the amount of the first extractant can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, llwt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, or 20wt%, and the amount of the second extractant can be 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, or 5.0wt%. During the scandium extraction, the first extractant serves as a main extractant while the second extractant serves as an auxiliary extractant, or in other words, as a modifier in the composite extractant. The composite extractant further has advantages of a low pollution, a low toxicity and a low cost due to a low amount of the second extractant.

[0041] In some embodiments of the present disclosure, the second extractant has an amount of 0.5- 2wt% based on the total weight of the composite extractant. For example, the second extractant has an amount of 1.0wt%. The scandium extraction performance of the composite extractant which meets the further condition may be further improved. In addition, the composite extractant which meets the further condition is more environmentally friendly.

[0042] In some embodiments of the present disclosure, the acidic extractant is selected from a group including di-(2-ethylhexyl)phosphoric acid (P204), 2-ethylhexyl phosphoric acid mono-2- ethylhexyl ester (P507), di(l-methyl-heptyl) methyl phosphonate (P350), diisooctylphosphinic acid (C272), 8-hydroxyquinoline and acidic phosphine (C301), and bis(2,4,4-trimethylpentyl) monothiophosphonic acid (C302); and / or, the neutral extractant is selected from a group including tributyl phosphate (TBP), trialkyl phosphine oxide (TRPO), and trialkyl phosphine oxide (TOPO); and / or, the alkaline extractant is selected from a group including secondary carbon primary amine (N 1923) and trioctyldecylamine tertiary amine (N235). The acidic extractant, the neutral extractant, and the alkaline extractant provided in the embodiments of the present disclosure are readily accessible.

[0043] In some embodiments of the present disclosure, the ketone compound is selected from a group including hexanone, heptanone, and octanone. That is, the ketone compound is any one of exanone, heptanone, and octanone or any combinations thereof. As an example, hexanone is selected as the second extractant doping in the composite extractant as its low toxicity, low irritating odor, and low cost. A low amount of the hexanone doping in the composite extractant can improve the scandium extraction performance and the repeatability of the composite extractant.

[0044] In some embodiments of the present disclosure, the ester compound is selected from a group including butyl acetate, butyl propionate, and butyl butyrate. That is, the ester compound is any one of butyl acetate, butyl propionate, and butyl butyrate or any combinations thereof. As an example, butyl acetate is selected as the second extractant doping in the composite extractant, so as to improve the scandium extraction performance and the repeatability of the composite extractant.

[0045] It is understandable that the second extractant can include any combinations of the ketone compound and the ester compound above. For example, the second extractant comprises heptanone and butyl propionate, and the total amount of heptanone and butyl propionate is in a range of 0.5wt% to 5wt% based on the total weight of the composite extractant.

[0046] In some embodiments of the present disclosure, sulphonated kerosene (or refers to 260# solvent oil) can be selected to be the diluent for the composite extractant. Method for scandium extraction

[0047] The embodiments of the present disclosure also provides a method for scandium extraction based on using the composite extractant in the above embodiments of the present disclosure. The method for scandium extraction includes:

[0048] 5101, mixing a scandium-containing acid solution with the composite extractant, according to the embodiments of the present disclosure, for extraction, and obtaining an extract solution after phase separation;

[0049] 5102, adding a first alkali solution into the extract solution for back-extraction to obtain a scandium-rich slag;

[0050] 5103, adding an acid solution into the scandium-rich slag for acid dissolution to obtain a scandium-rich aqueous solution;

[0051] 5104, adding a second alkali solution into the scandium -rich aqueous solution for precipitation to obtain a scandium hydroxide; and

[0052] 5105, performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product.

[0053] It should be noted that the above steps may be performed in sequence or not. That is, the steps may be performed in the sequence as the numbering of the steps, or in any other suitable sequence.

[0054] According to the method for scandium extraction in the embodiments of the present disclosure, with a usage of the composite extractant for extraction, the problem of generating the third phase during scandium extraction is solved, and the phase separation is easier to operate, which achieved the scandium extraction from the scandium-containing acid solution with a simple process and a high scandium extraction rate, reducing a loss of extractant and lowing an extraction cost. Benefiting from the enhanced scandium extraction performance of the composite extractant, the scandium oxide product produced according to the method for scandium extraction of the present disclosure has a low impurity content and a high purity, which contributes to a high-value utilization of scandium.

[0055] In some embodiments of the present disclosure, the scandium-containing acid solution in SlOlis selected from a group including titanium white waste acid solution, mixed nickel-cobalt hydroxide precipitate acid leaching solution and laterite nickel ore acid leaching solution.

[0056] In some embodiments, the scandium-containing acid solution include the scandium with a concentration ranging from 10 to 10000 ppm. The method for scandium extraction of the present disclosure can extract the scandium from the scandium-containing acid solution in the high scandium extraction rate.

[0057] In some embodiments of the present disclosure, in S101, a volume ratio of the scandium- containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1, such as 1 :3, 1 :2, 1 : 1, 2: 1, 3: 1, and 4: 1. In some embodiments, in S 101, the extraction has an extraction temperature ranging from 20 to 60°C. It can be noted that the extraction temperature of the method of the present disclosure is relatively mild, which further simplifies the operation for scandium extraction.

[0058] In some embodiments of the present disclosure, in SI 02, the first alkali solution is selected from a group including sodium hydroxide solution and potassium hydroxide solution. In some embodiments, the first alkali solution has a concentration ranging from 0.4mol / L to 2mol / L, such as 0.4mol / L, 0.8mol / L, l.Omol / L, 1.5mol / L and 2.0mol / L. In some embodiments, a volume ratio of the first alkali solution to the extract solution is in a range from 1 :3 to 3 : 1, such as 1 :3, 1:2, 1 : 1, 2: 1, and 3 : 1. In some embodiments, the back-extraction has a back-extraction temperature ranging from 50 to 100°C. After the back-extraction, the scandium is enriched in the scandium-rich slag, the scandium-rich slag is obtained by solid-liquid separation, and the composite extractant is reused after oil-water separation.

[0059] In some embodiments of the present disclosure, in S103, the acid solution is selected from a group including sulfuric acid solution, hydrochloric acid solution and nitric acid solution. In some embodiments, the acid solution has a concentration ranging from 0.5mol / L to 3mol / L, such as 0.5mol / L, l.Omol / L, 1.5mol / L, 2.0mol / L, 2.5mol / L and 3.0mol / L. After the acid dissolution, scandium ion dissolves in the scandium-rich aqueous solution, and impurities may be removed.

[0060] In some embodiments of the present disclosure, in SI 04, the second alkali solution is selected from a group including sodium hydroxide solution and potassium hydroxide solution. It should be noted that the first alkali solution can be the same or different with the second alkali solution, which is not limited in the present disclosure.

[0061] In some embodiments, in SI 04, the second alkali solution has a concentration ranging from 0.4mol / L to 2mol / L, such as 0.4mol / L, 0.8mol / L, l.Omol / L, 1.5mol / L and 2.0mol / L. It should be noted that the concentration of the first alkali solution can be the same or different with that of the second alkali solution, which is not limited in the present disclosure.

[0062] In some embodiments, in SI 04, a volume ratio of the second alkali solution to the scandium - rich aqueous solution is in a range from 1 :3 to 3: 1, such as 1 :3, 1 :2, 1 : 1, 2: 1, and 3: 1. In some embodiments, the precipitation process has a precipitation temperature ranging from 10 to 40 °C. After the precipitation, the refined scandium hydroxide can be obtained

[0063] In some embodiments of the present disclosure, in SI 05, the pyrolysis process has a pyrolysis temperature ranging from 400 to 900 °C. In some embodiments, a pyrolysis duration ranging from 0.5h to 5. Oh. The scandium oxide product with the high purity is generated through a high- temperature pyrolysis of the scandium hydroxide

[0064] Another method for scandium extraction

[0065] The embodiments of the present disclosure provides another method for scandium extraction based on using the composite extractant in the above embodiments of the present disclosure. The method for scandium extraction includes:

[0066] 5201, mixing a scandium-containing acid solution with the composite extractant, according to the embodiments of the present disclosure, and obtaining an extract solution after phase separation;

[0067] 5202, adding a third alkali solution into the extract solution for back-extraction to obtain a scandium hydroxide; and

[0068] 5203, performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product.

[0069] According to the method for scandium extraction in the embodiments of the present disclosure, benefiting from the enhanced scandium extraction performance of the composite extractant, the scandium hydroxide obtained after the back-extraction has a low impurity content and a high purity, the scandium oxide product can be thus obtained directly by performing the pyrolysis on the scandium hydroxide, which further simplifies the extraction process, and the scandium oxide product has a desirable purity.

[0070] In some embodiments of the present disclosure, the scandium-containing acid solution in S201 is selected from a group including titanium white waste acid solution, mixed nickel-cobalt hydroxide precipitate acid leaching solution and laterite nickel ore acid leaching solution.

[0071] In some embodiments, the scandium-containing acid solution include the scandium with a concentration ranging from 10 to 10000 ppm. The method for scandium extraction of the present disclosure can extract the scandium from the scandium-containing acid solution in the high scandium extraction rate.

[0072] In some embodiments of the present disclosure, in S201, a volume ratio of the scandium- containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1, such as 1 :3, 1 :2, 1 : 1, 2: 1, 3: 1, and 4: 1. In some embodiments, in S201, the extraction has an extraction temperature ranging from 20 to 60°C. It can be noted that the extraction temperature of the method of the present disclosure is relatively mild, which further simplifies the operation for scandium extraction.

[0073] In some embodiments of the present disclosure, in S202, the third alkali solution is selected from a group including sodium hydroxide solution and potassium hydroxide solution. In some embodiments, the third alkali solution has a concentration ranging from 0.4mol / L to 2mol / L, such as 0.4mol / L, 0.8mol / L, l.Omol / L, 1.5mol / L and 2.0mol / L. In some embodiments, a volume ratio of the third alkali solution to the extract solution is in a range from 1 :3 to 3 : 1, such as 1 :3, 1:2, 1 : 1, 2: 1, and 3 : 1. In some embodiments, the back-extraction has a back-extraction temperature ranging from 50 to 100°C. After the back-extraction, the scandium is enriched in the scandium-rich slag, the scandium-rich slag is obtained by solid-liquid separation, and the composite extractant is reused after oil-water separation.

[0074] In some embodiments of the present disclosure, in S203, the pyrolysis process has a pyrolysis temperature ranging from 400 to 900 °C. In some embodiments, a pyrolysis duration ranging from 0.5 to 5.0 h. The scandium oxide product with the high purity is generated through a high- temperature pyrolysis of the scandium hydroxide

[0075] Scandium oxide product

[0076] The embodiments of the present disclosure provides a scandium oxide product is provided. The scandium oxide product is prepared by the method for scandium extraction according to any embodiment of the present disclosure. The scandium oxide product of the embodiments of the present disclosure has a low impurity content and a high purity.

[0077] Experimental Section

[0078] The following Examples are included to demonstrate certain aspects and embodiments of the present disclosure. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the present disclosure.

[0079] Test methods

[0080] Metal content in a solution and the purity of the product are quantitatively analyzed by an inductively coupled plasma (ICP) spectrometer, and the following are an instrument model and detailed instrument parameters.

[0081] Table 1, Metal content ICP analysis conditions Model Agilent ICP 715

[0082] Power: 1.10 Kw

[0083] Plasma gas flow rate: 15.0 L / min

[0084] Auxiliary gas flow rate: 1.50 L / min Observation height: 10 mm Parameters One reading time: 5 S

[0085] Instrument stability delay: 15 S

[0086] Sample injection delay: 30 S Pump rate: 15 rpm Cleaning period: IO S

[0087] It should be noted that the present disclosure only describes some test method and conditions.

[0088] Materials, measurements and processes that are known in the art are not described herein.

[0089] Examples

[0090] Inventive Example 1 (IE1)

[0091] A scandium-containing acid solution with a scandium concentration of 500ppm was mixed with a composite extractant for extraction. The composite extractant contained P204 (lOwt %), hexanone (2.0wt %) and sulphonated kerosene (the rest). A volume ratio of the scandium- containing acid solution to the composite extractant was 1 :4, and the extraction had an extraction temperature of 20°C. An extract solution was obtained after phase separation.

[0092] Sodium hydroxide aqueous solution (the first alkali solution) with a concentration of 0.4mol / L was added into the extract solution for back-extraction. A volume ratio of the sodium hydroxide solution to the extract solution was 1 :3, and the back-extraction had a back-extraction temperature of 50°C. After the back-extraction, a scandium-rich slag was obtained by solid-liquid separation, and the composite extractant was reused after oil-water separation.

[0093] Sulfuric acid solution with a concentration of 0.5mol / L was added into the scandium-rich slag for acid dissolution, so as to dissolve the scandium ion into a scandium-rich aqueous solution.

[0094] Sodium hydroxide aqueous solution (the second alkali solution) with a concentration of 0.4mol / L was added into the scandium-rich aqueous solution for precipitation. A volume ratio of the sodium hydroxide solution to the scandium-rich aqueous solution was 1 :3, and the precipitation process had a precipitation temperature of 10°C. After the precipitation process, a scandium hydroxide was obtained by solid-liquid separation.

[0095] The scandium hydroxide was pyrolyzed at a pyrolysis temperature of 400 °C for 2h, and a scandium oxide product was obtained.

[0096] Inventive Example 2 (IE2)

[0097] Scandium oxide product for IE2 was extracted in the same way as IE1 expect that a composite extractant containing butyl acetate as the second extractant was used for extraction.

[0098] Inventive Example 3 (TE3)

[0099] Scandium oxide product for IE3 was extracted in the same way as IE1 expect that hexanone contained in the composite extractant had an amount of 0.5wt % based on a total weight of the composite extractant.

[0100] Inventive Example 4 (IE4)

[0101] Scandium oxide product for IE4 was extracted in the same way as IE1 expect that hexanone contained in the composite extractant had an amount of l.Owt % based on a total weight of the composite extractant.

[0102] Inventive Example 5

[0103] Scandium oxide product for IE5 was extracted in the same way as IE1 expect that hexanone contained in the composite extractant had an amount of 3.0wt % based on a total weight of the composite extractant.

[0104] Inventive Example 6 (IE6)

[0105] Scandium oxide product for IE6 was extracted in the same way as IE1 expect that hexanone contained in the composite extractant had an amount of 4.0wt % based on a total weight of the composite extractant.

[0106] Inventive Example 7 (IE7)

[0107] Scandium oxide product for IE7 was extracted in the same way as IE1 expect that hexanone contained in the composite extractant had an amount of 5.0wt % based on a total weight of the composite extractant.

[0108] Inventive Example 8 (IE8)

[0109] Scandium oxide product for IE8 was extracted in the same way as IE1 expect that TRPO acted as the first extractant is added in the composite extractant with an amount of 15wt % based on a total weight of the composite extractant, and heptanone acted as the second extractant is added in the composite extractant with an amount of 2.0wt % based on a total weight of the composite extractant.

[0110] Inventive Example 9 (IE9)

[0111] Scandium oxide product for IE9 was extracted in the same way as IE1 expect that N1923 acted as the first extractant is added in the composite extractant with an amount of 5wt % based on a total weight of the composite extractant, and butyl acetate acted as the second extractant is added in the composite extractant with an amount of 5.0wt % based on a total weight of the composite extractant.

[0112] Inventive Example 10 (IE 10)

[0113] A scandium-containing acid solution with a scandium concentration of 500ppm was mixed with a composite extractant for extraction. The composite extractant contained P350 (lOwt %), butyl propionate (4.0wt %) and sulphonated kerosene (the rest). A volume ratio of the scandium- containing acid solution to the composite extractant was 1 : 1, and the extraction had an extraction temperature of 40°C. An extract solution was obtained after phase separation.

[0114] Sodium hydroxide aqueous solution (the third alkali solution) with a concentration of l.Omol / L was added into the extract solution for back-extraction. A volume ratio of the sodium hydroxide solution to the extract solution was 1 : 1, and the back-extraction had a back-extraction temperature of 80°C. After the back-extraction, a scandium hydroxide was obtained by solid-liquid separation, and the composite extractant was reused after oil-water separation.

[0115] The scandium hydroxide was pyrolyzed at a pyrolysis temperature of 600 °C for 5h, and a scandium oxide product was obtained.

[0116] Inventive Example 11 (IE11)

[0117] Scandium oxide product for IE11 was extracted in the same way as IE10 expect that P204 acted as the first extractant in the composite extractant has an amount of 5wt % based on a total weight of the composite extractant, and octanone acted as the second extractant is added in the composite extractant with an amount of 3.0wt % based on a total weight of the composite extractant.

[0118] Inventive Example 12 (IE 12)

[0119] Scandium oxide product for IE12 was extracted in the same way as IE10 expect that TOPO acted as the first extractant is added in the composite extractant with an amount of lOwt % based on a total weight of the composite extractant, and hexanone acted as the second extractant is added in the composite extractant with an amount of 2.0wt % based on a total weight of the composite extractant.

[0120] Inventive Example 13 (IE13)

[0121] Scandium oxide product for IE13 was extracted in the same way as IE10 expect that N235 acted as the first extractant is added in the composite extractant with an amount of lOwt % based on a total weight of the composite extractant, and butyl acetate acted as the second extractant is added in the composite extractant with an amount of 2.0wt % based on a total weight of the composite extractant.

[0122] Comparative Example 1 (CE1)

[0123] Scandium oxide product for CE1 was extracted in the same way as IE1 expect that an extractant used during extraction only contains P204 (lOwt %) and sulphonated kerosene (the rest).

[0124] Comparative Example 2 (CE2)

[0125] Scandium oxide product for CE2 was extracted in the same way as IE1 expect that an extractant used during extraction only contains TOPO (15wt %) and sulphonated kerosene (the rest).

[0126] Comparative Example 3 (CE3)

[0127] Scandium oxide product for CE3 was extracted in the same way as IE1 expect that an extractant used during extraction only contains N235 (20wt %) and sulphonated kerosene (the rest).

[0128] Comparative Example 4 (CE4)

[0129] Scandium oxide product for CE2 was extracted in the same way as IE10 expect that an extractant used during extraction only contains P204 (lOwt %) and sulphonated kerosene (the rest).

[0130] Comparative Example 5 (CE5)

[0131] Scandium oxide product for CE5 was extracted in the same way as IE1 expect that an extractant used during extraction contains P204 (lOwt %), n-octanol (2.0wt %) and sulphonated kerosene (the rest).

[0132] Comparative Example 6 (CE6)

[0133] Scandium oxide product for CE6 was extracted in the same way as IE1 expect that an extractant used during extraction contains P204 (lOwt %), n-octanol (lO.Owt %) and sulphonated kerosene (the rest). Table 2

[0134] As we can see from the results of IE1 to IE9, benefiting from the enhanced scandium extraction performance of the composite extractant, the scandium oxide product produced according to the method for scandium extraction of the present disclosure has a low impurity content and a high purity, and the purity of the scandium oxide product produced increases with the amount of the second extractant in the composited extractant. Nevertheless, an excellent purity (about 98.9%) can be obtained with a minimal amount of the second extractant according to IE3, which illustrates the enhanced scandium extraction performance of the composite extractant of the present disclosure.

[0135] By comparing the results of IE1 to IE9, with CE1 to CE3, it can be seen that with a usage of the composite extractant of the present disclosure for scandium extraction, the scandium oxide product obtained has an excellent purity, usually higher than 99%, which is significantly increased compared with the purity (less than 93.0%) of the scandium oxide product obtained in CE1 to CE3, in which the extractant used for scandium extraction only has one effective component.

[0136] Based on the results of IE1 to IE13, it can be seen that in IE10 to IE13, although a simpler method is used to obtain the scandium oxide product, in which steps of acid dissolution and precipitation are omitted, benefiting from the enhanced scandium extraction performance of the composite extractant of the present disclosure, the scandium oxide product obtained still exhibits an excellent purity (large than 95.0%).

[0137] By comparing the results of IE10 with CE4, it can be seen that with a usage of the composite extractant of the present disclosure for extraction, the scandium oxide product obtained has a significantly increased purity compared with the scandium oxide product obtained in CE4, in CE4, the extractant used for extraction only has one effective component.

[0138] By comparing the results of IE1 to IE9, CE1 to CE3, CE5, and CE6, it can be seen that with a usage of the extractant in which uses alcohol compound (for example n-octanol in CE5 and CE6) serves as a modifier, the scandium oxide product obtained has an increased purity (for example about 90.0% in CE5). However, at the same amount, a usage of the ketone compound or the ester compound as the modifier in the composite extractant of the present disclosure can further increase the purity of the scandium oxide product. Besides, according to CE6, although the purity of the scandium oxide product can be improved by increase the amount of n-octanol, it is still not as effective as the present disclosure.

[0139] Reference throughout this specification to “an embodiment,” “some embodiments,” “one embodiment”, “another example,” “an example,” “a specific example,” or “some examples,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as “in some embodiments,” “in one embodiment”, “in an embodiment”, “in another example,” “in an example,” “in a specific example,” or “in some examples,” in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0140] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed here. This application is intended to cover any variations, uses, or adaptations of the disclosure following the general principles thereof and including such departures from the present disclosure as come within known or customary practice in the art. It is intended that the specification and examples be considered as illustrative only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

CLAIMS1. A composite extractant for scandium extraction, comprising: a first extractant comprising at least one selected from an acidic extractant, a neutral extractant, and an alkaline extractant; a second extractant comprising at least one selected from a ketone compound and an ester compound; and a diluent; wherein the first extractant has an amount of 5-20wt% based on a total weight of the composite extractant, and the second extractant has an amount of 0.5-5wt% based on a total weight of the composite extractant.

2. The composite extractant according to claim 1, wherein the acidic extractant is selected from a group comprising di-(2-ethylhexyl)phosphoric acid, 2-ethylhexyl phosphoric acid mono- 2-ethylhexyl ester, di(l-methyl-heptyl) methyl phosphonate, diisooctylphosphinic acid, 8- hydroxy quinoline and acidic phosphine, and bis(2,4,4-trimethylpentyl) monothiophosphonic acid; and / or the neutral extractant is selected from a group comprising tributyl phosphate, trialkyl phosphine oxide, and trialkyl phosphine oxide; and / or the alkaline extractant is selected from a group comprising secondary carbon primary amine and trioctyldecylamine tertiary amine.

3. The composite extractant according to claim 1 or 2, wherein the ketone compound is selected from a group comprising hexanone, heptanone, and octanone.

4. The composite extractant according to any one of claims 1 to 3, wherein the ester compound is selected from a group comprising butyl acetate, butyl propionate, and butyl butyrate.

5. The composite extractant according to any one of claims 1 to 4, wherein the second extractant has an amount of 0.5-2wt% based on a total weight of the composite extractant.

6. A method for scandium extraction, comprising mixing a scandium-containing acid solution with the composite extractant according to any one of claims 1 to 5 for extraction, and obtaining an extract solution after phase separation; adding a first alkali solution into the extract solution for back-extraction to obtain a scandium- rich slag; adding an acid solution into the scandium-rich slag for acid dissolution to obtain a scandium- rich aqueous solution; adding a second alkali solution into the scandium-rich aqueous solution for precipitation to obtain a scandium hydroxide; and performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product.

7. The method according to claim 6, wherein the scandium-containing acid solution is selected from a group comprising titanium white waste acid solution, mixed nickel-cobalt hydroxide precipitate acid leaching solution and laterite nickel ore acid leaching solution; and / or the scandium-containing acid solution comprises a scandium with a concentration ranging from 10 to 10000 ppm.

8. The method according to claim 6 or 7, wherein a volume ratio of the scandium-containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1; and / or the extraction has an extraction temperature ranging from 20 to 60°C.

9. The method according to any one of claims 6-8, wherein the first alkali solution is selected from a group comprising sodium hydroxide solution and potassium hydroxide solution; and / or the first alkali solution has a concentration of 0.4mol / L-2mol / L; and / or a volume ratio of the first alkali solution to the extract solution is in a range from 1 :3 to 3: 1; and / or the back-extraction has a back-extraction temperature ranging from 50 to 100°C.

10. The method according to any one of claims 6-9, wherein the acid solution is selected from a group comprising sulfuric acid solution, hydrochloric acid solution and nitric acid solution; and / orthe acid solution has a concentration of 0.5mol / L -3mol / L.

11. The method according to any one of claims 6-10, wherein the second alkali solution is selected from a group comprising sodium hydroxide solution and potassium hydroxide solution, and / or the second alkali solution has a concentration of 0.4mol / L -2mol / L; and / or a volume ratio of the second alkali solution to the scandium-rich aqueous solution is in a range from 1 :3 to 3: 1; and / or the precipitation has a precipitation temperature ranging from 10 to 40 °C.

12. The method according to any one of claims 6-11, wherein the pyrolysis has a pyrolysis temperature ranging from 400 to 900 °C, and / or a pyrolysis duration ranging from 0.5 to 5.0 h.

13. A method for scandium extraction, comprising mixing a scandium-containing acid solution with the composite extractant according to any one of claims 1 to 5 for extraction, and obtaining an extract solution after phase separation; adding a third alkali solution into the extract solution for back-extraction to obtain a scandium hydroxide; and performing a pyrolysis on the scandium hydroxide to obtain a scandium oxide product.

14. The method according to claim 13, wherein the scandium-containing acid solution is selected from a group comprising titanium white waste acid solution and mixed nickel-cobalt hydroxide precipitate acid leaching solution; and / or the scandium-containing acid solution comprising a scandium with a concentration ranging from 10 to 10000 ppm.

15. The method according to claim 13 or 14, wherein a volume ratio of the scandium- containing acid solution to the composite extractant is in a range from 1 :4 to 4: 1; and / or the extraction has an extraction temperature ranging from 20 to 60°C.

16. The method according to any one of claims 13-15, wherein the third alkali solution isselected from a group comprising sodium hydroxide solution and potassium hydroxide solution; and / or the third alkali solution has a concentration of 0.4mol / L-2mol / L; and / or a volume ratio of the third alkali solution to the extract solution is in a range from 1 :3 to 3 : 1; and / or the back-extraction has a back-extraction temperature ranging from 50 to 100°C.

17. The method according to any one of claims 13-16, wherein the pyrolysis has a pyrolysis temperature ranging from 400 to 900 °C, and / or a pyrolysis duration ranging from 0.5 to 5.0 h.

18. A scandium oxide product prepared by the method according to any one of claims 6 to 17.

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