Method for recovering scandium oxide from scandium slag, scandium oxide and application of scandium oxide

Abstract

The invention relates to the technical field of hydrometallurgy, in particular to a method for recycling scandium oxide from scandium slag, scandium oxide and application of the scandium oxide. According to the method, the scandium residues obtained from MHP are subjected to acid leaching, then pass through an N1923 extraction section, then pass through a P350 extraction section and then pass through an N235 extraction section, and finally a scandium chloride solution is subjected to scandium precipitation treatment and roasting, so that high-purity scandium oxide is obtained. The method has the advantages that an alkali reverse flow required by a scandium-containing loaded organic phase is avoided, the whole extraction section can be performed in an extraction tank without filtering operation, the automation degree is high, the continuity is good, the flow is short, and the acid consumption is greatly reduced, meanwhile, the amine extraction agent N1923 is firstly used and has strong selectivity on scandium, and when the amine extraction agent N1923 is used for separating most impurities in the first extraction section, the scandium content is greatly reduced; the temperature required by extraction and reverse extraction is lower than the temperature required by an acidic phosphine extraction agent, so that aging and deterioration of an organic phase are avoided, the stage number of the reverse extraction stage is greatly reduced, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for recovering scandium oxide from scandium slag, scandium oxide and applications thereof. Background Art

[0002] Scandium metal, scandium oxide and scandium alloy are widely used in aerospace, metallurgy, chemical industry and clean energy. In the process of pressure acid leaching (HPAL) of laterite nickel ore, scandium is mainly distributed in the production of nickel cobalt hydroxide intermediate product (MHP). Due to the huge amount of MHP processing in recent years, the output of scandium as a by-product has also increased. In the prior art, after acid leaching of MHP, the pH of the leaching solution is adjusted and then a reducing agent is added to precipitate scandium. After filter pressing, a scandium-rich slag is obtained, and the scandium-rich slag is then acid-dissolved to obtain a scandium liquid. Compared with tungsten, titanium or rare earth metal deposits or metallurgical waste slag as scandium-containing raw materials, the scandium liquid obtained from MHP basically does not contain rare earth elements, so the purification process of scandium is relatively simple.

[0003] At present, most of the domestic industrial processes for purifying scandium in MHP use acidic phosphine extractants, such as P204 extractant, P507 extractant, etc., because they have high selectivity for scandium at a specific pH value and can effectively separate scandium from impurity elements and are widely used.

[0004] However, the scandium-loaded organic phase obtained by extraction with an acidic phosphine extractant needs to be stripped with liquid alkali, and then dissolved and adjusted in hydrochloric acid, which consumes a lot of acid. The scandium-rich solution obtained after stripping is a suspension, which needs to be filtered and has poor continuity. Liquid alkali requires a series of post-treatments, which is long and costly. In addition, most impurities are separated first with an acidic phosphine extractant, and the organic phase is easily aged or deteriorated due to high-temperature stripping, and the stripping stages are relatively large.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for recovering scandium oxide from scandium slag, which does not use an acidic phosphine extractant, avoids the alkaline backflow process required for the scandium-loaded organic phase, and the entire extraction process can be carried out in an extraction tank without filtering operation, with high automation, good continuity, short process and low cost; at the same time, the present invention fully considers the characteristics of the extractant, and in addition to the back-extraction operation, it is not necessary to add acid to adjust the acidity of the extraction liquid, so the acid consumption is greatly reduced. In addition, the present invention first uses an amine extractant N1923, which has a strong selectivity for scandium. When used as the first extraction process to separate most impurities, the temperature required for extraction and back-extraction is lower than the temperature required for the acidic phosphine extractant, and there is basically no problem of aging or deterioration of the organic phase due to high temperature, and the number of stages in the back-extraction stage is also greatly reduced, which is more conducive to saving production costs.

[0007] A second object of the present invention is to provide scandium oxide having high purity.

[0008] The third object of the present invention is to provide applications of scandium oxide in the fields of aerospace, information technology, metallurgy and chemical industry, and clean energy.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] The present invention first provides a method for recovering scandium oxide from scandium slag, comprising the following steps:

[0011] (a), mixing the scandium slag obtained from MHP with sulfuric acid and leaching, and then separating the solid and liquid to obtain a leachate; using N1923 extractant to perform a first extraction on the leachate to obtain an N1923 organic phase and an N1923 aqueous phase; wherein the N1923 extractant is mainly composed of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene; and after washing the N1923 organic phase, performing a first stripping with hydrochloric acid to obtain an N1923 stripping solution;

[0012] (b), using a P350 extractant to perform a second extraction on the N1923 stripping solution to obtain a P350 organic phase and a P350 aqueous phase; wherein the P350 extractant is mainly composed of dimethylheptyl methylphosphonate and sulfonated kerosene; and using hydrochloric acid to perform a second stripping on the P350 organic phase to obtain a P350 stripping solution;

[0013] (c), performing a third extraction on the P350 stripping solution using an N235 extractant to obtain an N235 organic phase and an N235 aqueous phase; wherein the N235 extractant is mainly composed of trioctyldecyl tertiary amine, secondary octanol and sulfonated kerosene;

[0014] (d) adjusting the pH of the N235 aqueous phase and adding a precipitant to precipitate scandium, obtaining a precipitate containing scandium after solid-liquid separation, and calcining the precipitate containing scandium to obtain scandium oxide.

[0015] Furthermore, in step (a), the volume ratio of the secondary carbon primary amine, the isooctyl alcohol and the sulfonated kerosene in the N1923 extractant is 15-25:5-15:60-80.

[0016] Furthermore, in step (a), the volume ratio of the N1923 extractant to the leaching solution is 2 to 5:1.

[0017] Furthermore, in step (a), the first extraction is 2 to 5 stages of extraction.

[0018] Furthermore, in step (a), the temperature of the first extraction is 40-55°C.

[0019] Furthermore, in step (a), the N1923 organic phase is washed using a sulfuric acid solution having a molar concentration of 0.5 to 2 mol / L; preferably, the volume ratio of the sulfuric acid solution used for washing to the N1923 organic phase is 2 to 4:1; preferably, the washing is a 5 to 12-stage washing.

[0020] Furthermore, in step (a), the first stripping is carried out using a hydrochloric acid solution with a molar concentration of 3 to 5 mol / L.

[0021] Furthermore, in step (a), during the first stripping process, the volume ratio of the hydrochloric acid to the washed N1923 organic phase is 3 to 5:1.

[0022] Furthermore, in step (a), the first stripping is 3 to 5 stages of stripping.

[0023] Furthermore, in step (a), the temperature of the first stripping is 40-55°C.

[0024] Furthermore, in step (a), the sulfuric acid used for leaching includes 0.5 to 3 mol / L dilute sulfuric acid.

[0025] Furthermore, in step (a), the endpoint acidity of the leaching is 0.2 to 1.0 mol / L.

[0026] Furthermore, in step (b), the volume ratio of the dimethylheptyl methylphosphonate to the sulfonated kerosene in the P350 extractant is 30-50:50-70.

[0027] Furthermore, in step (b), the volume ratio of the P350 extractant to the N1923 stripping solution is 2 to 4:1.

[0028] Furthermore, in step (b), the second extraction is 5 to 12 stages of extraction.

[0029] Furthermore, in step (b), the temperature of the second extraction is 40-55°C.

[0030] Furthermore, in step (b), the second stripping is carried out using hydrochloric acid with a molar concentration of 1 to 2 mol / L.

[0031] Furthermore, in step (b), during the second stripping process, the volume ratio of the hydrochloric acid to the P350 organic phase is 1 to 2:1.

[0032] Furthermore, in step (b), the second stripping is 2 to 4 stages of stripping.

[0033] Furthermore, in step (b), the temperature of the second stripping is 40-55°C.

[0034] Furthermore, in step (c), the volume ratio of the trioctyldecyl tertiary amine, the secondary octanol and the sulfonated kerosene in the N235 extractant is 5-25:5-15:60-90.

[0035] Furthermore, in step (c), the volume ratio of the N235 extractant to the P350 stripping solution is 1 to 4:1.

[0036] Furthermore, in step (c), the third extraction is 1 to 3 levels of extraction.

[0037] Furthermore, in step (d), the pH of the N235 aqueous phase is adjusted to 1.0-2.0.

[0038] Furthermore, in step (d), a neutralizing agent is used to adjust the pH of the N235 aqueous phase, and the neutralizing agent includes at least one of an aqueous ammonia solution, an ammonium carbonate solution and an ammonium bicarbonate solution.

[0039] Furthermore, in step (d), the precipitant comprises an oxalic acid solution with a mass fraction of 5% to 10%.

[0040] Furthermore, in step (d), the temperature of the scandium precipitation treatment is 45-90°C.

[0041] Furthermore, in step (d), the scandium precipitation treatment time is 0.5 to 1 hour.

[0042] Furthermore, in step (d), the reaction pH of the scandium precipitation treatment is 1.0 to 2.0.

[0043] Furthermore, in step (d), the calcination temperature is 1000-1100°C.

[0044] Furthermore, in step (d), the calcination holding time is 4 to 6 hours.

[0045] The present invention further provides scandium oxide prepared by the method for recovering scandium oxide from scandium slag, wherein the purity of the scandium oxide is greater than 99.9%.

[0046] The present invention also provides the application of the scandium oxide in the fields of aerospace, information technology, metallurgy and chemical industry, and clean energy.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The method for recovering scandium oxide from scandium slag provided by the present invention does not use an acidic phosphine extractant, thus avoiding the alkaline backflow process required for the scandium-loaded organic phase. The entire extraction process can be carried out in the extraction tank without the need for filtering operations, with a high degree of automation, good continuity, a short process, and low cost. At the same time, the present invention fully considers the characteristics of the extractant, and in addition to the back-extraction operation, no additional acid needs to be added to adjust the acidity of the extraction liquid, so the acid consumption is greatly reduced. In addition, the present invention first uses an amine extractant N1923, which has a strong selectivity for scandium. When used as the first extraction process to separate most impurities, the temperature required for extraction and back-extraction is lower than that required for an acidic phosphine extractant, and there is basically no problem of aging or deterioration of the organic phase due to high temperature, and the number of stages in the back-extraction stage is also greatly reduced, which is more conducive to saving production costs.

[0049] (2) Compared with the conventional P204 extraction process, the method for recovering scandium oxide from scandium slag provided by the present invention fully considers the characteristics of the raw materials and the characteristics of the extractant, and avoids the disadvantages of high-temperature stripping of loaded organic using liquid alkali through the optimized combination of the extractant and the metal extraction performance, thereby greatly improving the production processing efficiency and safety.

[0050] (3) The method for recovering scandium oxide from scandium slag provided by the present invention fully considers the specific acidity values ​​required for extraction and stripping of N1923, P350 and N235 extractants, and does not need to adjust the acidity with acid or alkali before entering the next extraction stage. The method requires fewer total stages for extraction, shorter process, excellent recyclability of the extractant, and low production cost.

[0051] (4) The method for recovering scandium oxide from scandium slag provided by the present invention has a high scandium recovery rate, and the purity of the scandium oxide obtained is above 99.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A schematic flow chart of a method for recovering scandium oxide from scandium slag provided by the present invention. DETAILED DESCRIPTION

[0054] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0055] In a first aspect, the present invention provides a method for recovering scandium oxide from scandium slag, and also a method for extracting and purifying scandium from scandium slag, comprising the following steps:

[0056] (a) The scandium slag obtained from MHP is mixed with sulfuric acid and leached, and then the solid and liquid are separated to obtain a leachate, which is the N1923 extraction liquid.

[0057] It is understood that the leaching solution obtained after acid leaching of the MHP raw material is subjected to reduction precipitation and filtration to obtain the scandium slag obtained from the MHP.

[0058] The leachate is subjected to a first extraction using an N1923 extractant to obtain an N1923 organic phase and an N1923 aqueous phase; wherein the N1923 extractant is mainly composed of secondary carbon primary amines, isooctyl alcohol and sulfonated kerosene; the N1923 organic phase is washed and then subjected to a first stripping using hydrochloric acid to obtain an N1923 stripping solution, which is the P350 extraction feed solution and also the scandium chloride solution.

[0059] (b) performing a second extraction on the N1923 stripping solution with a P350 extractant to obtain a P350 organic phase and a P350 aqueous phase; wherein the P350 extractant is mainly composed of dimethylheptyl methylphosphonate and sulfonated kerosene; and performing a second stripping on the P350 organic phase with hydrochloric acid to obtain a P350 stripping solution, which is the N235 extraction feed solution and also the scandium chloride solution.

[0060] (c) performing a third extraction on the P350 stripping solution using an N235 extractant to obtain an N235 organic phase and an N235 aqueous phase, i.e., a scandium-rich solution. The N235 extractant is mainly composed of trioctyldecyl tertiary amine, sec-octanol, and sulfonated kerosene.

[0061] (d) adjusting the pH of the N235 aqueous phase and adding a precipitant to precipitate scandium, obtaining a precipitate containing scandium after solid-liquid separation, and calcining the precipitate containing scandium to obtain scandium oxide.

[0062] The present invention uses an extraction process to recover scandium oxide from the scandium slag obtained from MHP, wherein the process first passes through an N1923 extraction section, then passes through a P350 extraction section, and then passes through an N235 extraction section.

[0063] Specifically, the present invention uses sulfuric acid to leach the scandium slag obtained from MHP, and then inputs the leachate into the N1923 extraction section. At this time, the pH of the system is appropriate, and the scandium, iron, calcium, sodium, silicon, etc. in the leachate enter the N1923 organic phase, while most of the impurity elements remain in the solution to form the N1923 aqueous phase. Subsequently, the N1923 organic phase is washed to separate sodium and silicon from the organic phase. Then, the N1923 organic phase is stripped with hydrochloric acid to separate scandium from the organic phase to obtain a crude scandium chloride solution containing a small amount of iron and calcium (i.e., N1923 stripping solution). The remaining organic phase from the stripping can be recycled as an extractant for N1923 extraction.

[0064] Further, the obtained scandium chloride crude solution (i.e., N1923 stripping solution) is input into the P350 extraction section, at which time the system pH is suitable, scandium and iron enter the P350 organic phase, and most of the calcium remains in the solution to form the P350 aqueous phase. The P350 organic phase is then stripped with hydrochloric acid to obtain a further impurity-free scandium chloride solution (i.e., P350 stripping solution). The stripped P350 organic phase is further washed, and the remaining organic phase can be recycled as a P350 extractant.

[0065] Furthermore, the scandium chloride solution (i.e., P350 stripping solution) that has been further decontaminated is input into the N235 extraction section. At this time, the system pH is suitable, iron enters the N235 organic phase, and most of the scandium remains in the solution to form the N235 aqueous phase, that is, a refined scandium chloride solution is obtained. The organic phase is then stripped with pure water, and the remaining organic phase can be recycled as an extractant for N235 extraction.

[0066] Furthermore, the obtained refined scandium chloride solution is subjected to scandium precipitation treatment, which can leave trace impurity elements in the solution in the aqueous phase, and the scandium-containing precipitate is calcined at high temperature to obtain high-purity scandium oxide.

[0067] The method for recovering scandium oxide from scandium slag provided by the present invention does not use an acidic phosphine extractant, thus avoiding the alkaline back-extraction process required for the scandium-loaded organic phase. The entire extraction process can be carried out in an extraction tank without the need for filtering operations, and has a high degree of automation, good continuity, a short process, and low costs. At the same time, the present invention fully considers the characteristics of the extractant, and except for the back-extraction operation, does not need to add acid to adjust the acidity of the extraction liquid, thereby greatly reducing acid consumption.

[0068] In addition, the present invention first uses the amine extractant N1923, which has a strong selectivity for scandium. When used as the first extraction stage to separate most impurities, the temperature required for extraction and stripping is lower than the temperature required for the acidic phosphine extractant, and there is basically no problem of aging or deterioration of the organic phase due to high temperature, and the number of stages in the stripping stage is also greatly reduced, which is more conducive to saving production costs.

[0069] The process flow of the present invention fully considers the extraction principles of N1923 extractant, P350 extractant and N235 extractant, wherein N1923 extractant needs an extraction liquid of a sulfuric acid system to react, P350 extractant and N235 extractant need an extraction liquid of a hydrochloric acid system to react, and the organic load after N1923 extracts scandium needs to be stripped off with hydrochloric acid, which just completes the system conversion of the extraction liquid from sulfuric acid to hydrochloric acid. However, the extraction and back extraction of the P350 and N235 sections cannot achieve the conversion of the extraction liquid from hydrochloric acid to sulfuric acid system. If the extraction section of P350 or N235 is carried out first, the obtained hydrochloric acid back extraction liquid cannot be extracted after entering N1923. The extraction and back extraction of the N1923 section is the only system conversion means of this process, so the extraction operation sequence of the first step using the N1923 extractant in the present invention cannot be replaced by P350 and N235. On the other hand, in addition to the ability to extract iron ions, the N235 extractant also has the ability to extract hydrochloric acid. If the stripping solution obtained after the N1923 stripping is first subjected to the N235 extraction, the acidity of the extract will decrease, affecting the subsequent P350 extractant's ability to extract scandium. Therefore, the extraction operation sequence of the process flow N1923-P350-N235 of the present invention cannot be adjusted.

[0070] like Figure 1 Shown is a schematic flow chart of the method for recovering scandium oxide from scandium slag provided by the present invention.

[0071] In some specific embodiments, in step (a), the volume ratio of the secondary carbon primary amine, the isooctyl alcohol and the sulfonated kerosene in the N1923 extractant is 15-25 (including but not limited to any one of 15, 16, 18, 20, 22, 23, 25 or any range between two): 5-15 (including but not limited to any one of 5, 6, 7, 8, 9, 10, 12, 13, 15 or any range between two): 60-80 (including but not limited to any one of 60, 63, 65, 68, 70, 72, 75, 77, 80 or any range between two). By controlling the ratio of the secondary carbon primary amine, it is beneficial to improve the extraction rate of scandium; by controlling the ratio of isooctyl alcohol, the phase separation time of the extraction process can be significantly reduced.

[0072] In some specific embodiments, in step (a), the volume ratio of the N1923 extractant to the leaching solution is 2 to 5:1, including but not limited to any point value of 2:1, 3:1, 4:1, 5:1 or a range value between any two of them. When the volume ratio of the N1923 extractant to the leaching solution is 2 to 5:1, the extraction rate of scandium is high and the utilization efficiency of the extractant is high.

[0073] In some specific embodiments, in step (a), the first extraction is 2 to 5 stage extraction, such as 2 stage extraction, 3 stage extraction, 4 stage extraction or 5 stage extraction.

[0074] In some specific embodiments, in step (a), the temperature of the first extraction is 40-55°C, including but not limited to any one of 40°C, 42°C, 43°C, 44°C, 45°C, 46°C, 48°C, 50°C, 53°C, and 55°C, or a range between any two of them.

[0075] In some specific embodiments, in step (a), the N1923 organic phase is washed with a sulfuric acid solution having a molar concentration of 0.5 to 2 mol / L, wherein the molar concentration of the sulfuric acid solution includes but is not limited to any one of 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, and 2 mol / L or a range between any two of them.

[0076] In some specific embodiments, the volume ratio of the sulfuric acid solution used for washing to the N1923 organic phase is 2 to 4:1, including but not limited to any point value of 2:1, 3:1, 4:1 or a range value between any two of them.

[0077] In some specific embodiments, the washing is 5 to 12 stages of washing; for example, 5 stages of washing, 6 stages of washing, 7 stages of washing, 8 stages of washing, 9 stages of washing, 10 stages of washing, 11 stages of washing, 13 stages of washing or 15 stages of washing.

[0078] In some specific embodiments, in step (a), the first stripping is carried out using a hydrochloric acid solution with a molar concentration of 3 to 5 mol / L; wherein the molar concentration of the hydrochloric acid solution includes but is not limited to any point value of 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L or a range value between any two of them.

[0079] In some specific embodiments, in step (a), during the first stripping process, the volume ratio of the hydrochloric acid to the washed N1923 organic phase is 3 to 5:1, including but not limited to any one of 3:1, 4:1, 5:1 or a range between any two of them.

[0080] In some specific embodiments, in step (a), the first stripping is 3 to 5 stage stripping, for example, 3 stage stripping, 4 stage stripping or 5 stage stripping.

[0081] Traditionally, the number of stripping stages using acidic phosphine extractants is relatively large, usually more than 10 stages. However, the number of stages of the first stripping of the present invention is relatively small, which is beneficial to reducing production costs.

[0082] The invention has fewer stripping stages, which is beneficial to shortening the process time and reducing the cost.

[0083] In some specific embodiments, in step (a), the temperature of the first stripping is 40-55°C, including but not limited to any one of 40°C, 42°C, 43°C, 44°C, 45°C, 46°C, 48°C, 50°C, 53°C, and 55°C, or a range between any two of them.

[0084] The stripping temperature of the scandium-loaded organic phase obtained by the conventional process using an acidic phosphine extractant is 70-80° C., which is relatively high and easily causes the extractant to age or deteriorate. However, the first stripping temperature of the present invention is low, which can avoid the problem of aging or deterioration of the extractant.

[0085] In some specific implementations, in step (a), the sulfuric acid used for leaching includes 0.5-3 mol / L dilute sulfuric acid.

[0086] In some specific embodiments, in step (a), the acidity of the endpoint of the leaching is 0.2-1.0 mol / L, including but not limited to any one of 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L or any range between two thereof. Wherein, acidity refers to hydrogen ion concentration. The endpoint acidity of the leaching is the molar concentration of hydrogen ions in the leaching endpoint reaction system. As the acidity of the endpoint increases, scandium can be better leached from the raw material, but too high an endpoint acidity will increase the cost of treating wastewater. Therefore, the present invention selects 0.2-1.0 mol / L as the endpoint acidity of the leaching, taking into account both the leaching effect and the cost.

[0087] In some specific embodiments, in step (a), if the acidity at the leaching end point is too high, water may be added to the leaching solution for dilution.

[0088] In some specific embodiments, in step (b), the volume ratio of the dimethylheptyl methylphosphonate and the sulfonated kerosene in the P350 extractant is 30-50 (including but not limited to any one of 30, 32, 35, 38, 40, 42, 45, 47, 50 or a range between any two): 50-70 (including but not limited to any one of 50, 53, 55, 58, 60, 63, 65, 68, 70 or a range between any two). The above ratio of dimethylheptyl methylphosphonate and sulfonated kerosene can reduce the phase separation time during stripping.

[0089] In some specific embodiments, in step (b), the volume ratio of the P350 extractant to the N1923 stripping solution is 2 to 4:1, including but not limited to any point value of 2:1, 3:1, 4:1 or a range value between any two of them.

[0090] In some specific embodiments, in step (b), the second extraction is 5 to 12 stage extraction; for example, 5 stage extraction, 6 stage extraction, 7 stage extraction, 8 stage extraction, 10 stage extraction or 12 stage extraction.

[0091] In some specific embodiments, in step (b), the temperature of the second extraction is 40-55°C, including but not limited to any one of 40°C, 42°C, 43°C, 44°C, 45°C, 46°C, 48°C, 50°C, 53°C, and 55°C, or a range between any two of them.

[0092] In some specific embodiments, in step (b), the second stripping is carried out using hydrochloric acid with a molar concentration of 1 to 2 mol / L. The molar concentration of hydrochloric acid includes, but is not limited to, any one of 1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, and 2 mol / L, or a range between any two of them.

[0093] In some specific embodiments, in step (b), during the second stripping process, the volume ratio of the hydrochloric acid to the P350 organic phase is 1 to 2:1.

[0094] In some specific embodiments, in step (b), the second stripping is 2 to 4 stage stripping, for example, 2 stage stripping, 3 stage stripping or 4 stage stripping.

[0095] In some specific embodiments, in step (b), the temperature of the second stripping is 40-55°C, including but not limited to any one of 40°C, 42°C, 43°C, 44°C, 45°C, 46°C, 48°C, 50°C, 53°C, and 55°C, or a range between any two of them.

[0096] In some specific embodiments, in step (c), the volume ratio of the trioctyl decyl tertiary amine, the secondary octanol and the sulfonated kerosene in the N235 extractant is 5-25 (including but not limited to any one of 5, 7, 8, 9, 10, 12, 13, 15, 18, 20, 23, 25 or any range between two): 5-15 (including but not limited to any one of 5, 7, 8, 9, 10, 12, 13, 15 or any range between two): 60-90 (including but not limited to any one of 60, 63, 65, 68, 70, 72, 75, 77, 80, 82, 85, 87, 90 or any range between two). The present invention has a good extraction effect on iron ions and a high utilization efficiency of the extractant by controlling the ratio of the trioctyl decyl tertiary amine; by controlling the ratio of the secondary octanol, the phenomenon of the third phase appearing during phase separation during the extraction process can be effectively avoided.

[0097] In some specific embodiments, in step (c), the volume ratio of the N235 extractant to the P350 stripping solution is 1 to 4:1, including but not limited to any point value of 1:1, 2:1, 3:1, 4:1 or a range value between any two of them.

[0098] In some specific embodiments, in step (c), the third extraction is 1 to 3 stage extraction, such as 1, 2 or 3 stage.

[0099] In some specific embodiments, in step (c), the temperature of the third extraction is room temperature, for example, 10-30°C, including but not limited to any point value of 10°C, 15°C, 20°C, 25°C, 30°C or a range value between any two of them.

[0100] In some specific embodiments, in step (d), the pH of the N235 aqueous phase is adjusted to 1.0-2.0; including but not limited to any point value of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 2.0 or any range value between two of them. In the present invention, when the pH of the N235 aqueous phase is 1.0-2.0, a higher extraction rate of iron ions is achieved.

[0101] In some specific embodiments, in step (d), a neutralizing agent is used to adjust the pH of the N235 aqueous phase, wherein the neutralizing agent comprises at least one of an aqueous ammonia solution, an ammonium carbonate solution and an ammonium bicarbonate solution.

[0102] In some specific embodiments, in step (d), the precipitant comprises an oxalic acid solution having a mass fraction of 5% to 10%. The mass fraction of the oxalic acid solution includes, but is not limited to, any one of 5%, 6%, 7%, 8%, 9%, and 10%, or a range of values ​​between any two of them.

[0103] In some specific embodiments, in step (d), the temperature of the scandium precipitation treatment is 45-90°C, including but not limited to any point value of 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or any range value between two of them.

[0104] In some specific implementations, in step (d), the scandium precipitation treatment time is 0.5 to 1 h, such as 0.6 h or 0.8 h.

[0105] In some specific embodiments, in step (d), the reaction pH of the scandium precipitation treatment is 1.0-2.0, that is, the pH of the reaction system during the scandium precipitation treatment is 1.0-2.0, including but not limited to any point value of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 2.0 or a range value between any two of them.

[0106] In some specific embodiments, in step (d), the calcination temperature is 1000-1100°C, including but not limited to any point value of 1000°C, 1010°C, 1020°C, 1030°C, 1050°C, 1060°C, 1080°C, 1100°C or a range between any two of them.

[0107] In some specific implementations, in step (d), the calcination holding time is 4 to 6 hours, for example, 5 hours.

[0108] In a second aspect, the present invention provides a scandium oxide obtained by the above method for recovering scandium oxide from scandium slag, wherein the purity of the scandium oxide is >99.9%.

[0109] The method for recovering scandium oxide from scandium slag provided by the present invention can obtain high-purity scandium oxide, which is beneficial to the wide application of scandium metal, scandium alloy and the like.

[0110] In a third aspect, the present invention provides applications of the scandium oxide in the fields of aerospace, information technology, metallurgy and chemical industry, and clean energy.

[0111] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0112] The scandium slag obtained from MHP used in the following examples and comparative examples is obtained by reducing, precipitating and filtering the leaching liquid obtained by acid leaching the MHP raw material.

[0113] Example 1

[0114] The method for recovering scandium oxide from scandium slag provided in this embodiment comprises the following steps:

[0115] (1) 1000 g of scandium slag obtained from MHP was leached with 1 mol / L dilute sulfuric acid and filtered to obtain a leachate with an acidity (i.e., hydrogen ion concentration) of 0.91 mol / L. The acidity of the leachate was then adjusted to 0.5 mol / L with water to serve as the extraction feed solution for N1923;

[0116] (2) The volume ratio of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is 20:15:65 to prepare N1923 extractant.

[0117] (3) performing a three-stage extraction (i.e., the first extraction) with the N1923 extractant and the N1923 extractant obtained in step (1) at a volume ratio of 4:1 to obtain an N1923 organic phase and an N1923 aqueous phase;

[0118] 2 mol / L sulfuric acid and N1923 organic phase were used for 7-stage washing at a volume ratio of 3.6:1 to remove other impurities except scandium, iron and calcium.

[0119] The washed N1923 organic phase was subjected to three-stage stripping (i.e., the first stripping) using 3 mol / L hydrochloric acid at a volume ratio of 4:1 to obtain a crude scandium chloride solution as the P350 extraction feed solution (i.e., N1923 stripping solution).

[0120] (4) preparing P350 extractant with a volume ratio of dimethylheptyl methylphosphonate to sulfonated kerosene of 40:60;

[0121] (5) subjecting the P350 extractant and the P350 extract solution obtained in step (3) to five-stage extraction (i.e., the second extraction) at a volume ratio of 2:1 to obtain a P350 organic phase and a P350 aqueous phase;

[0122] The P350 organic phase was subjected to three-stage stripping (i.e., the second stripping) with a volume ratio of 2:1 using 1 mol / L hydrochloric acid, and the phase separation time during stripping was within 5 minutes, thereby obtaining a further impurity-free scandium chloride solution, i.e., N235 extract solution (i.e., P350 stripping solution);

[0123] (6) preparing N235 extractant with trioctyldecyl tertiary amine, sec-octanol, and sulfonated kerosene in a volume ratio of 5:10:85;

[0124] (7) The N235 extractant and the N235 extractant obtained in step (5) are subjected to a second-stage extraction (i.e., the third extraction) at a volume ratio of 2:1 to obtain an N235 organic phase and an N235 aqueous phase, wherein the N235 aqueous phase is a scandium chloride solution.

[0125] (8) Using ammonia water as a neutralizing agent, the pH of the scandium chloride solution in step (7) is adjusted to 1.5, and then 10% oxalic acid solution is added to the scandium chloride solution as a precipitant, and ammonia water is continuously added during the reaction to control the pH at 1.5, and the reaction is carried out at 80° C. for 1 hour. After the scandium precipitation treatment, the solution is filtered to obtain a scandium-containing precipitate.

[0126] The scandium-containing precipitate in step (8) is calcined at 1000° C. for 4 hours to obtain scandium oxide.

[0127] Example 2

[0128] The method for recovering scandium oxide from scandium slag provided in this embodiment comprises the following steps:

[0129] (1) 1000 g of scandium slag obtained from MHP was leached with 1 mol / L dilute sulfuric acid and filtered to obtain a leachate with an acidity of 0.91 mol / L. The acidity of the leachate was then adjusted to 0.5 mol / L with water as the extraction feed solution for N1923;

[0130] (2) The volume ratio of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is 25:15:60 to prepare N1923 extractant.

[0131] (3) extracting the N1923 extractant and the N1923 extractant obtained in step (1) in a volume ratio of 4:1 to perform five-stage extraction to obtain an N1923 organic phase and an N1923 aqueous phase;

[0132] 2 mol / L sulfuric acid and N1923 organic phase were used for 7-stage washing at a volume ratio of 3.6:1 to remove other impurities except scandium, iron and calcium.

[0133] The washed N1923 organic phase was subjected to three-stage stripping using 3 mol / L hydrochloric acid at a volume ratio of 4:1 to obtain a crude scandium chloride solution as the P350 extraction feed solution.

[0134] (4) preparing P350 extractant with a volume ratio of dimethylheptyl methylphosphonate to sulfonated kerosene of 40:60;

[0135] (5) extracting the P350 extractant and the P350 extract solution obtained in step (3) at a volume ratio of 2:1 for 10 steps to obtain a P350 organic phase and a P350 aqueous phase;

[0136] The P350 organic phase was stripped in three stages with 1 mol / L hydrochloric acid at a volume ratio of 2:1. The phase separation time during stripping was within 5 minutes, and a further impurity-free scandium chloride solution, namely, N235 extraction solution, was obtained.

[0137] (6) preparing N235 extractant with a volume ratio of 10:10:80 of trioctyldecyl tertiary amine, sec-octanol, and sulfonated kerosene;

[0138] (7) The N235 extractant and the N235 extractant obtained in step (5) are subjected to a second-stage extraction at a volume ratio of 3:1 to obtain an N235 organic phase and an N235 aqueous phase, wherein the N235 aqueous phase is a scandium chloride solution.

[0139] (8) Using an aqueous ammonia solution as a neutralizing agent, the pH of the scandium chloride solution in step (7) is adjusted to 1.5, and then a 10% oxalic acid solution is added to the scandium chloride solution as a precipitant, and the aqueous ammonia solution is continuously added during the reaction to control the pH at 1.8, and the reaction is carried out at 80° C. for 1 hour. After the scandium precipitation treatment, the solution is filtered to obtain a precipitate containing scandium.

[0140] The scandium-containing precipitate in step (8) is calcined at 1000° C. for 4 hours to obtain scandium oxide.

[0141] Example 3

[0142] The method for recovering scandium oxide from scandium slag provided in this embodiment comprises the following steps:

[0143] (1) 1000 g of scandium slag obtained from MHP was leached with 1 mol / L dilute sulfuric acid and filtered to obtain a leachate with an acidity of 0.91 mol / L. The acidity of the leachate was then adjusted to 0.5 mol / L with water as the extraction feed solution for N1923;

[0144] (2) The volume ratio of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is 20:15:65 to prepare N1923 extractant.

[0145] (3) extracting the N1923 extractant and the N1923 extractant obtained in step (1) in a volume ratio of 4:1 to perform five-stage extraction to obtain an N1923 organic phase and an N1923 aqueous phase;

[0146] 2 mol / L sulfuric acid and N1923 organic phase were washed in 12 stages at a volume ratio of 3.6:1 to remove impurities other than scandium, iron and calcium.

[0147] The washed N1923 organic phase was subjected to three-stage stripping using 3 mol / L hydrochloric acid at a volume ratio of 4:1 to obtain a crude scandium chloride solution as the P350 extraction feed solution.

[0148] (4) preparing P350 extractant with a volume ratio of dimethylheptyl methylphosphonate to sulfonated kerosene of 30:70;

[0149] (5) extracting the P350 extractant and the P350 extract solution obtained in step (3) at a volume ratio of 2:1 for 12 steps to obtain a P350 organic phase and a P350 aqueous phase;

[0150] The P350 organic phase was stripped in three stages with 1 mol / L hydrochloric acid at a volume ratio of 2:1. The phase separation time during stripping was within 5 minutes, and a further impurity-free scandium chloride solution, namely, N235 extraction solution, was obtained.

[0151] (6) preparing N235 extractant with trioctyldecyl tertiary amine, sec-octanol, and sulfonated kerosene in a volume ratio of 5:10:85;

[0152] (7) The N235 extractant and the N235 extractant obtained in step (5) are subjected to a second-stage extraction at a volume ratio of 4:1 to obtain an N235 organic phase and an N235 aqueous phase, wherein the N235 aqueous phase is a scandium chloride solution.

[0153] (8) Using ammonia water as a neutralizing agent, the pH of the scandium chloride solution in step (7) is adjusted to 1.5, and then 5% oxalic acid solution is added to the scandium chloride solution as a precipitant, and ammonia water is continuously added during the reaction to control the pH at 1.3, and the reaction is carried out at 80° C. for 1 hour. After the scandium precipitation treatment, the solution is filtered to obtain a scandium-containing precipitate.

[0154] The scandium-containing precipitate in step (8) is calcined at 1000° C. for 4 hours to obtain scandium oxide.

[0155] Example 4

[0156] The method for recovering scandium oxide from scandium slag provided in this embodiment is basically the same as that in embodiment 1, except that in step (2), the volume ratio of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is replaced with 15:5:80.

[0157] Example 5

[0158] The method for recovering scandium oxide from scandium slag provided in this embodiment is basically the same as that in Example 1, except that in step (3), the volume ratio of N1923 extractant to N1923 extract solution is replaced with 2:1; and the volume ratio of hydrochloric acid to washed N1923 organic phase is replaced with 5:1.

[0159] Example 6

[0160] The method for recovering scandium oxide from scandium slag provided in this embodiment is basically the same as that in embodiment 1, except that in step (4), the volume ratio of dimethylheptylphosphonate to sulfonated kerosene is replaced with 50:50.

[0161] Example 7

[0162] The method for recovering scandium oxide from scandium slag provided in this embodiment is basically the same as that in Example 1, except that in step (5), the volume ratio of P350 extractant to P350 extract solution is replaced with 4:1; and the volume ratio of hydrochloric acid to P350 organic phase is replaced with 1:1.

[0163] Example 8

[0164] The method for recovering scandium oxide from scandium slag provided in this embodiment is basically the same as that in embodiment 1, except that in step (6), the volume ratio of trioctyldecyl tertiary amine, secondary octanol and sulfonated kerosene is replaced with 25:5:60.

[0165] Comparative Example 1

[0166] The method for recovering scandium oxide from scandium slag provided in this comparative example is basically the same as that in Example 1, except that in step (2), the volume ratio of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is replaced with 30:20:50.

[0167] Comparative Example 2

[0168] The method for recovering scandium oxide from scandium slag provided in this comparative example is basically the same as that in Example 1, except that in step (4), the volume ratio of dimethylheptylphosphonate to sulfonated kerosene is replaced with 60:40. The phase separation time during stripping in step (5) of this comparative example is more than 1 hour.

[0169] Comparative Example 3

[0170] The method for recovering scandium oxide from scandium slag provided in this comparative example is basically the same as that in Example 1, except that in step (6), the volume ratio of trioctyldecyl tertiary amine, secondary octanol and sulfonated kerosene is replaced with 30:20:50.

[0171] The chemical composition of the leaching solution obtained after leaching the scandium slag with dilute sulfuric acid in each embodiment and each comparative example is shown in Table 1.

[0172] Table 1 Chemical composition of the leachate

[0173] element Sc Ni Cu Fe Ca Mg Na Al Si Content (g / L) 22.42 5.84 11.12 1.42 0.045 0.033 2.69 1.68 0.039

[0174] In each embodiment and each comparative example, step (3) uses N1923 extractant for the first extraction, and the extraction rate of each element is shown in Table 2.

[0175] Table 2 Extraction rate of each element in the first extraction using N1923 extractant (%)

[0176] element Sc Ni Cu Fe Ca Mg Na Al Si Example 1 99.36 0.21 0.0032 5.42 1.56 0.043 0.087 0.35 0.059 Example 2 99.64 0.25 0.0054 5.68 1.55 0.036 0.098 0.42 0.057 Example 3 99.07 0.2 0.0028 5.33 1.47 0.028 0.047 0.28 0.018 Example 4 98.28 0.17 0.0034 5.28 1.36 0.041 0.080 0.31 0.055 Example 5 93.87 0.18 0.0030 5.34 1.38 0.039 0.074 0.33 0.054 Example 6 99.28 0.20 0.0031 5.44 1.59 0.041 0.090 0.34 0.058 Example 7 99.34 0.21 0.0038 5.38 1.59 0.043 0.081 0.34 0.049 Example 8 99.28 0.19 0.0041 5.48 1.58 0.041 0.079 0.35 0.051 Comparative Example 1 99.68 0.27 0.0055 5.89 1.58 0.036 0.092 0.47 0.042 Comparative Example 2 99.32 0.21 0.0031 5.48 1.57 0.041 0.084 0.27 0.053 Comparative Example 3 99.48 0.21 0.0048 5.34 1.51 0.044 0.075 0.34 0.048

[0177] In each embodiment and each comparative example, step (5) uses P350 extractant for the second extraction, and the extraction rate of each element is shown in Table 3.

[0178] Table 3 Extraction rate of each element in the second extraction using P350 extractant (%)

[0179]

[0180]

[0181] In each embodiment and each comparative example, step (7) uses N235 extractant for the third extraction, and the extraction rate of each element is shown in Table 4.

[0182] Table 4 Extraction rate of each element in the third extraction using N235 extractant (%)

[0183] element Sc Ni Cu Fe Ca Mg Na Al Si Example 1 1.59 0.0084 0.0005 >99.9 0.0079 0.0078 0.0005 30.78 1.32 Example 2 2.04 0.012 0.0008 >99.9 0.010 0.0087 0.0008 45.89 2.48 Example 3 1.89 0.0079 0.0006 >99.9 0.0082 0.0063 0.0005 37.84 1.08 Example 4 1.48 0.0087 0.0005 >99.9 0.0075 0.0077 0.0005 33.78 1.34 Example 5 1.53 0.0079 0.0005 >99.9 0.0077 0.0080 0.0005 32.45 1.29 Example 6 1.57 0.0087 0.0005 >99.9 0.0097 0.0084 0.0006 47.66 2.37 Example 7 1.48 0.0078 0.0008 >99.9 0.0099 0.0087 0.0009 46.36 2.84 Example 8 2.31 0.0110 0.0008 >99.9 0.0120 0.0077 0.0008 49.33 2.43 Comparative Example 1 1.59 0.0074 0.0006 >99.9 0.0074 0.0082 0.0006 30.24 1.39 Comparative Example 2 1.42 0.0092 0.0004 >99.9 0.0076 0.0084 0.0005 33.47 1.29 Comparative Example 3 2.98 0.0190 0.0008 >99.9 0.0130 0.0083 0.0008 44.57 2.38

[0184] The scandium yield and the purity of the scandium oxide obtained in the scandium precipitation treatment in step (8) in each embodiment and each comparative example are shown in Table 5.

[0185] Table 5 Scandium precipitation treatment scandium yield and the purity of the resulting scandium oxide

[0186]

[0187]

[0188] From the results of Tables 1 to 5, it can be seen that the total scandium recovery rate of each embodiment (total scandium recovery rate = first extraction scandium recovery rate × second extraction scandium recovery rate × (1-third extraction scandium recovery rate) × scandium recovery rate of precipitation scandium treatment) is > 90%, the impurity element separation effect is good, and the final scandium oxide purity is > 99.9%. It can be seen that the technical solution of the present invention can efficiently separate scandium from impurity elements while maintaining a high scandium recovery rate, and can obtain high-purity scandium oxide.

[0189] In Comparative Example 1, the volume ratio of the secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene is not suitable. Although the extraction rate of scandium in the first extraction is not much different from that in Example 1, the amount of extractant is increased by 50%, the utilization rate of the extractant is low, and the production cost is increased.

[0190] In Comparative Example 2, the volume ratio of dimethylheptylphosphonate to sulfonated kerosene is not suitable. Although the extraction rate of scandium in the second extraction is not much different from that in Example 1, the phase separation time during stripping in Comparative Example 2 reaches more than 1 hour, which is significantly longer than the phase separation time during stripping in Example 1, which is not conducive to actual production operation.

[0191] In Comparative Example 3, the volume ratio of trioctyldecyl tertiary amine, sec-octanol and sulfonated kerosene is not suitable. Although the extraction rate of iron in the third extraction is basically the same as that in Example 1, the extraction rate of scandium is increased by 1.39%, resulting in the loss of scandium. In addition, the amount of extractant used is increased by 6 times, the utilization rate of the extractant is extremely low, and the production cost is significantly increased.

[0192] In summary, the present invention solves the problems that the scandium-loaded organic phase obtained by extraction with an acidic phosphine extractant needs to be stripped with liquid alkali and then dissolved with hydrochloric acid to adjust the acidity, the amount of acid consumed is very large, and the scandium-rich solution obtained after stripping is a suspension, which needs to go through a filtration process and has poor continuity, the liquid alkali requires a series of post-treatments, the process is long and the cost is high, the acidic phosphine extractant is used to first separate most impurities, the organic phase is easily aged or deteriorated due to high-temperature stripping, and the number of stripping stages is relatively large, while the present invention has a high scandium recovery rate, obtains high-purity scandium oxide, saves the production process, and significantly reduces the cost.

[0193] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for recovering scandium oxide from scandium slag, characterized in that: The steps include: (a), mixing the scandium slag obtained from MHP with sulfuric acid and leaching, and then separating the solid and liquid to obtain a leachate; using N1923 extractant to perform a first extraction on the leachate to obtain an N1923 organic phase and an N1923 aqueous phase; wherein the N1923 extractant is mainly composed of secondary carbon primary amine, isooctyl alcohol and sulfonated kerosene; and after washing the N1923 organic phase, performing a first stripping with hydrochloric acid to obtain an N1923 stripping solution; (b), using a P350 extractant to perform a second extraction on the N1923 stripping solution to obtain a P350 organic phase and a P350 aqueous phase; wherein the P350 extractant is mainly composed of dimethylheptyl methylphosphonate and sulfonated kerosene; and using hydrochloric acid to perform a second stripping on the P350 organic phase to obtain a P350 stripping solution; (c), performing a third extraction on the P350 stripping solution using an N235 extractant to obtain an N235 organic phase and an N235 aqueous phase; wherein the N235 extractant is mainly composed of trioctyldecyl tertiary amine, secondary octanol and sulfonated kerosene; (d) adjusting the pH of the N235 aqueous phase and adding a precipitant to precipitate scandium, obtaining a precipitate containing scandium after solid-liquid separation, and calcining the precipitate containing scandium to obtain scandium oxide.

2. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (a), at least one of the following conditions is met: (1) The volume ratio of the secondary carbon primary amine, the isooctyl alcohol and the sulfonated kerosene in the N1923 extractant is 15-25:5-15:60-80; (2) the volume ratio of the N1923 extractant to the leaching solution is 2 to 5:1; (3) The first extraction is 2 to 5 stages of extraction; (4) The temperature of the first extraction is 40-55°C.

3. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (a), at least one of the following conditions is met: (1) washing the N1923 organic phase with a sulfuric acid solution having a molar concentration of 0.5 to 2 mol / L; preferably, the volume ratio of the sulfuric acid solution used for washing to the N1923 organic phase is 2 to 4:1; preferably, the washing is 5 to 12 stages of washing; (2) using a hydrochloric acid solution with a molar concentration of 3 to 5 mol / L to perform the first stripping; (3) During the first stripping process, the volume ratio of the hydrochloric acid to the washed N1923 organic phase is 3 to 5:1; (4) the first stripping is 3 to 5 stages of stripping; (5) The temperature of the first stripping is 40-55°C.

4. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (a), at least one of the following conditions is met: (1) The sulfuric acid used in the leaching includes 0.5-3 mol / L dilute sulfuric acid; (2) The endpoint acidity of the leaching is 0.2-1.0 mol / L.

5. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (b), at least one of the following conditions is met: (1) The volume ratio of the dimethylheptyl methylphosphonate to the sulfonated kerosene in the P350 extractant is 30-50:50-70; (2) the volume ratio of the P350 extractant to the N1923 stripping solution is 2 to 4:1; (3) The second extraction is 5 to 12 stages of extraction; (4) The temperature of the second extraction is 40 to 55° C.; (5) using hydrochloric acid with a molar concentration of 1 to 2 mol / L to perform the second stripping; (6) During the second stripping process, the volume ratio of the hydrochloric acid to the P350 organic phase is 1 to 2:1; (7) The second stripping is 2 to 4 stages of stripping; (8) The temperature of the second stripping is 40-55°C.

6. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (c), at least one of the following conditions is met: (1) The volume ratio of the trioctyldecyl tertiary amine, the secondary octanol and the sulfonated kerosene in the N235 extractant is 5-25:5-15:60-90; (2) the volume ratio of the N235 extractant to the P350 stripping solution is 1 to 4:1; (3) The third extraction is 1 to 3 levels of extraction.

7. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (d), at least one of the following conditions is met: (1) The pH of the N235 aqueous phase is adjusted to 1.0-2.0; (2) adjusting the pH of the N235 aqueous phase using a neutralizer, wherein the neutralizer comprises at least one of an aqueous ammonia solution, an ammonium carbonate solution, and an ammonium bicarbonate solution; (3) The precipitant comprises an oxalic acid solution with a mass fraction of 5% to 10%.

8. The method for recovering scandium oxide from scandium slag according to claim 1, characterized in that: In step (d), at least one of the following conditions is met: (1) The temperature of the scandium precipitation treatment is 45 to 90° C.; (2) The scandium precipitation treatment time is 0.5 to 1 hour; (3) The reaction pH of the scandium precipitation treatment is 1.0 to 2.0; (4) The calcination temperature is 1000-1100° C.; (5) The heat preservation time of the calcination is 4 to 6 hours.

9. Scandium oxide obtained by the method for recovering scandium oxide from scandium slag according to any one of claims 1 to 8, characterized in that: The purity of the scandium oxide is >99.9%.

10. Application of scandium oxide as claimed in claim 9 in the fields of aerospace, information technology, metallurgy and chemical industry, and clean energy.

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