Method for extracting scandium from scandium-containing solid waste produced by chlorination method for extracting titanium

Abstract

The application discloses a method for extracting scandium from scandium-containing solid waste produced in the process of extracting titanium by chlorination, and the method comprises the following steps: water leaching the scandium-containing solid waste produced in the process of extracting titanium by chlorination to separate the leaching solution, reducing and precipitating the leaching solution, repeatedly performing the acid leaching-reduction-scandium precipitation process according to the scandium content in the scandium-containing precipitate, and obtaining a final scandium-rich material, wherein the number of repetitions is greater than or equal to 1; after the acid leaching, soluble phosphate is used for impurity removal, multi-stage countercurrent extraction and elution impurity removal are performed on the impurity removal liquid, the back-extraction substance is countercurrently washed by oxalic acid and high-temperature calcination, and finally, scandium oxide products with a purity greater than or equal to 99.9% are obtained. The method has the advantages of convenient operation, simple process flow, low production cost, good environmental protection benefit, easy industrialization, and efficient recovery of the valuable element scandium in the scandium-containing solid waste produced in the process of extracting titanium by chlorination.

Description

Technical Field

[0001] This invention belongs to the field of valuable resource recycling technology, specifically relating to a method for extracting scandium from scandium-containing solid waste generated from titanium extraction by the chlorination process. Background Technology

[0002] Scandium is a rare earth element and a strategic resource. Globally, scandium resources are abundant, with reserves of approximately 2 million tons. my country's scandium reserves are approximately 650,000 tons. However, more than 75% of scandium is associated with other minerals. The complex extraction process, low overall recovery rate, and high cost are the main reasons for the high price of scandium products. Scandium is known as one of the most expensive metals in the world. Domestic scandium resources are mainly distributed in bauxite and phosphate rock (including weathered leaching phosphate deposits), vanadium-titanium magnetite, tungsten, and rare earth minerals. Currently, scandium extraction raw materials mainly come from secondary resources such as waste liquid or solid waste generated during the comprehensive utilization of associated minerals. Existing secondary resources that can be used as scandium extraction raw materials include by-products of uranium ore, tungsten smelting slag, hydrolyzed acidic waste liquid generated from the sulfuric acid process for titanium dioxide production, chlorinated dust generated from boiling chlorination for titanium extraction, titanium-containing blast furnace slag, red mud, ion-adsorption type rare earth minerals, and Bayan Obo tailings. Different scandium-containing raw materials have different physicochemical properties, especially in terms of chemical composition and solubility in different leaching agents, which leads to different scandium extraction processes. Existing traditional scandium element extraction processes have technical defects such as complex processes, low recovery rates, and high costs. Summary of the Invention

[0003] To address the bottlenecks in traditional scandium extraction processes, this invention aims to provide a method for extracting scandium from scandium-containing solid waste generated during the titanium chlorination process. This method is convenient to operate, has a simple process flow, high efficiency, low production cost, and good environmental benefits. It is easily industrialized and can efficiently recover valuable scandium from the scandium-containing solid waste generated during the titanium chlorination process. The raw material for scandium extraction involved in this invention is primarily scandium-containing solid waste generated during the titanium chlorination process.

[0004] To achieve the above-mentioned invention, the present invention provides a method for extracting scandium from scandium-containing solid waste generated during titanium extraction by chlorination, the method comprising the following steps:

[0005] S1 uses water to pulp and dissolve scandium-containing solid waste, and after filtration, obtains scandium-containing leachate and residue. The residue is washed and filtered with water to obtain washed residue and wash water. The wash water is recycled for pulping and leaching.

[0006] S2 maintains the pH of the leachate ≤ 0.5, uses a reducing agent to fully reduce the target cation in the leachate, filters the obtained filtrate and residue, the residue is returned to the reduction process, uses a precipitating agent to precipitate scandium ions in the filtrate, and obtains filtrate and scandium-containing precipitate after filtration;

[0007] S3 uses an excess acid solution to leach the scandium in the scandium-containing precipitate, then uses a reducing agent to fully reduce the target cation in the leachate, filters the obtained filtrate and filter residue, and returns the filter residue to the reduction process, uses a precipitant to precipitate the scandium ions in the filtrate, filters the filtrate and scandium-containing precipitate, and repeats the acid leaching-reduction-scandium precipitation process according to the scandium content of the scandium-containing precipitate, repeating the process ≥1 time, and finally obtaining the scandium-containing precipitate as the ultimate scandium-rich material;

[0008] S4 uses an acidic solution to fully leach the scandium in the above-mentioned ultimate scandium-rich material, filters it to obtain a scandium leachate, and the leaching endpoint pH is ≤0.5. Then, a reducing agent is used to reduce the target cation in the leachate, filters it to obtain a reduced leachate, removes impurities with phosphate, and filters it to obtain a purified solution.

[0009] S5 uses a composite extractant to extract scandium ions from the above-mentioned impurity-removing solution in a multi-stage countercurrent manner, obtaining a scandium-loaded organic phase and a raffinate;

[0010] S6 uses a multi-stage countercurrent elution of a composite acid solution to remove residual metal impurities from the supported organic phase;

[0011] S7 uses sodium oxalate to perform multi-stage countercurrent back-extraction on the eluted scandium-loaded organic phase to obtain a back-extractant with a total impurity element content of <0.05%. The back-extractant is then washed with oxalic acid in a countercurrent manner and calcined at high temperature to finally obtain scandium oxide with a purity of ≥99.9%.

[0012] Furthermore, in S1, the scandium content in the scandium-containing solid waste is ≥10g / t, the liquid-solid ratio during dissolution is water volume (ml): scandium-containing waste residue mass (g) = 0.5~15:1, the pH of the leachate is maintained ≤2 throughout the dissolution process, the water used for leaching the scandium-containing waste residue and washing residue is purified industrial water, tap water, distilled water, or deionized water, the pH of the water is adjusted to 2~2.5 with hydrochloric acid before washing, the liquid-solid ratio during washing is water volume (ml): residue mass (g) = 2~10:1, the number of washing times is ≥1, preferably 3~5 times.

[0013] Furthermore, in S2, the target cation is trivalent iron or hexavalent chromium, and the reducing agent is one of iron, magnesium, zinc or aluminum metal powder or metal scrap, sodium metabisulfite, sodium sulfate, or oxalic acid. The amount of reducing agent used is 0.1–4 g / L of leachate, and the temperature of the leachate system during reduction is ≥40℃, preferably 60–95℃. The precipitant in the precipitation process is one or more of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, or ammonia water, and the pH at the precipitation endpoint is controlled at 3–6.

[0014] Furthermore, in S3, the acid used for leaching is sulfuric acid, hydrochloric acid, or nitric acid, with an acid concentration ≥1 mol / L, preferably 2–7 mol / L; the target cation is ferric iron, and the reducing agent is one of iron, magnesium, zinc, or aluminum metal powder or shavings, sodium metabisulfite, or sodium sulfate, with a reducing agent dosage of 0.01–2 g / L of leaching solution; the leaching solution system temperature during reduction is ≥40℃, preferably 60–95℃; the precipitant in the precipitation process is one or more of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, or ammonia water, with the pH at the precipitation endpoint controlled at 3–6; when the scandium content of the scandium-containing precipitate is ≥5%, the repeated acid leaching-reduction-scandium precipitation process is stopped.

[0015] Furthermore, in S4, the acid used for leaching is sulfuric acid, hydrochloric acid, or nitric acid, with an acid concentration ≥1 mol / L, preferably 2–7 mol / L; the target cation is ferric iron, and the reducing agent is one of iron, magnesium, zinc, or aluminum metal powder or shavings, sodium metabisulfite, or sodium sulfate. The amount of reducing agent used is 0.001–1 g / L of leaching solution, and the temperature of the leaching solution system during reduction is ≥40℃, preferably 60–95℃; the soluble phosphate used for impurity removal is sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, potassium monohydrogen phosphate, or potassium dihydrogen phosphate. The amount of soluble phosphate added per liter of scandium-containing leaching solution is 0.02–1 g, and a solution needs to be prepared before addition.

[0016] Furthermore, in S5, the volume percentage of each component of the composite extractant is 5-30% P204, 5-20% TBP, 0-10% Cyanex 302, and 50-90% 260# solvent oil or sulfonated kerosene; during extraction, the volume ratio of the organic phase composite extractant to the aqueous phase reduced leachate is 1-100:10, and the number of extraction stages is ≥1; the extraction equipment is an extraction tank, a hydrocyclone extractor, or a microchannel extraction device, and the extraction temperature is ≥5℃, preferably 20-50℃.

[0017] Furthermore, in S6, the composite acid solution includes an acid solution and a strong oxidizing agent. The acid solution is composed of sulfuric acid, hydrochloric acid, or a hydrochloric acid-sulfuric acid mixture. The strong oxidizing agent is hydrogen peroxide with a concentration of 0.1–2 mol / L. The elution stage is ≥1. The elution equipment is an extraction tank, a hydrocyclone extractor, or a microchannel extraction device. The elution temperature is ≥5°C, preferably 20–50°C.

[0018] Furthermore, in S7, the sodium oxalate concentration is 1–5 mol / L, the volume ratio of the supported organic phase to the sodium oxalate solution during back-extraction is 1:1–5, the number of back-extraction stages is ≥1, preferably 3–6; the back-extraction temperature is ≥5℃, preferably 20–50℃; the oxalic acid concentration for washing is ≥0.1 mol / L, preferably 0.3–1 mol / L, and the liquid-solid ratio during washing is oxalic acid solution volume (ml): scandium oxalate (wet material) weight (g) = 1–1 The 0:1 ratio of countercurrent washing stages is ≥3, preferably 4 to 10. The scandium oxalate after washing and filtration is calcined. During calcination, the temperature is increased to 105 to 125°C at a rate of 5 to 10°C / min and kept at this temperature to dry the precipitate until its moisture content is ≤3%. The temperature is then increased to ≥700°C at a rate of 10 to 40°C / min and kept at this temperature for ≥3 hours. The preferred calcination temperature is 800 to 1000°C and the preferred holding time is 5 to 8 hours.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention involves separating the leachate from scandium-containing solid waste generated during titanium extraction via the chlorination process. The leachate is then reduced and precipitated. The acid leaching-reduction-scandium precipitation process is repeated ≥1 times based on the scandium content of the precipitate to obtain a final scandium-rich material. After acid leaching, impurities are removed with soluble phosphates. The impurity-removing solution undergoes multi-stage countercurrent extraction and elution to remove impurities. The back-extracted material is then washed countercurrently with oxalic acid and calcined at high temperature to finally obtain a scandium oxide product with a purity ≥99.9%. This method is convenient to operate, has a simple process flow, low production cost, good environmental benefits, and is easy to industrialize. It can efficiently recover valuable scandium from scandium-containing solid waste generated during titanium extraction via the chlorination process. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but this does not limit the invention in any way. To avoid redundancy, unless otherwise specified, the raw materials used in the following embodiments are commercially available products, and the methods used are conventional methods unless otherwise specified. Unless otherwise specified, the specific processing conditions, operating steps, equipment, and instruments involved in this invention are all things that those skilled in the art can learn from the prior art without creative effort.

[0022] A method for extracting scandium from scandium-containing solid waste generated during titanium extraction via the chlorination process, the method comprising the following steps:

[0023] S1 uses water to pulp and dissolve scandium-containing solid waste, and after filtration, obtains scandium-containing leachate and residue. The residue is washed and filtered with water to obtain washed residue and wash water. The wash water is recycled for pulping and leaching.

[0024] S2 maintains the pH of the leachate ≤ 0.5, uses a reducing agent to fully reduce the target cation in the leachate, filters the obtained filtrate and residue, the residue is returned to the reduction process, uses a precipitating agent to precipitate scandium ions in the filtrate, and obtains filtrate and scandium-containing precipitate after filtration;

[0025] S3 uses an excess acid solution to leach the scandium in the scandium-containing precipitate, then uses a reducing agent to fully reduce the target cation in the leachate, filters the obtained filtrate and filter residue, and returns the filter residue to the reduction process, uses a precipitant to precipitate the scandium ions in the filtrate, filters the filtrate and scandium-containing precipitate, and repeats the acid leaching-reduction-scandium precipitation process according to the scandium content of the scandium-containing precipitate, repeating the process ≥1 time, and finally obtaining the scandium-containing precipitate as the ultimate scandium-rich material;

[0026] S4 uses an acidic solution to fully leach the scandium in the above-mentioned ultimate scandium-rich material, filters it to obtain a scandium leachate, and the leaching endpoint pH is ≤0.5. Then, a reducing agent is used to reduce the target cation in the leachate, filters it to obtain a reduced leachate, removes impurities with phosphate, and filters it to obtain a purified solution.

[0027] S5 uses a composite extractant to extract scandium ions from the above-mentioned impurity-removing solution in a multi-stage countercurrent manner, obtaining a scandium-loaded organic phase and a raffinate;

[0028] S6 uses a multi-stage countercurrent elution of a composite acid solution to remove residual metal impurities from the supported organic phase;

[0029] S7 uses sodium oxalate to perform multi-stage countercurrent back-extraction on the eluted scandium-loaded organic phase to obtain a back-extractant with a total impurity element content of <0.05%. The back-extractant is then washed with oxalic acid in a countercurrent manner and calcined at high temperature to finally obtain scandium oxide with a purity of ≥99.9%.

[0030] Example

[0031] The scandium-containing solid waste obtained from a certain sampling of titanium extraction by the chlorination process was fluidized bed chlorination dust collector residue, and its main components are shown in Table 1.

[0032] Table 1. Main components of fluidized bed chlorination dust collector residue obtained from a certain sampling.

[0033]

[0034] S1 involves pulping and dissolving a boiling chlorinated dust collector with a scandium content of 290 g / t using water. The liquid-to-solid ratio during dissolution is 3:1 (water volume ml : boiling chlorinated dust collector mass g). After filtration, a scandium-containing leachate and residue with a pH of 0.9 are obtained. The scandium leaching rate in this process is 97%, and the scandium concentration in the solution is 93.76 mg / L. The residue is then washed countercurrently with water whose pH is adjusted to 2.1 using hydrochloric acid. The liquid-to-solid ratio during washing is 2:1 (water volume ml : residue mass g), and the washing is performed four times. After filtration, the washed residue and wash water are obtained. The wash water is recycled for pulping and leaching.

[0035] S2 adjusts the pH of the above leaching solution to 0.4 with a 3 mol / L hydrochloric acid solution. Reduced iron powder is used to fully reduce trivalent iron and hexavalent chromium in the leaching solution. The amount of reduced iron powder used is 3 g / L of leaching solution. The reduction process is intensified with stirring until no solids settle at the bottom of the reactor. The reduction temperature is 60℃. Filtration yields filtrate and filter residue. The filter residue is returned to the reduction process. The pH of the filtrate is then adjusted to 4.7 with a 10% NaOH solution. Stirring is intensified again until no solids settle at the bottom of the reactor. The system temperature is 60℃. Filtration yields residual liquid and scandium-containing precipitate. The scandium recovery rate in this process is 99.91%. The precipitation rates of Mg, Fe, Mn, Ca, Zr, V, Ti, Si, Al, and Cr are 0.01%, 0.5%, 0.01%, 0.01%, 10.17%, 9.76%, 8.33%, 12.58%, 99.85%, and 99.79%, respectively.

[0036] S3 uses a 5 mol / L hydrochloric acid solution to dissolve the scandium-containing precipitate. The liquid-to-solid ratio is 2.5:1 (hydrochloric acid solution volume in ml : scandium precipitate mass in g (50% water content)). The ferric ions in the obtained solution are fully reduced using reduced iron powder at a concentration of 0.3 g / L solution. After complete reduction, the solution is filtered to obtain filtrate and residue. The residue is returned to the reduction process. The pH of the filtrate is adjusted to 4.0 using a 15% NaOH solution. The remaining liquid and scandium-rich material are then obtained. The acid leaching-reduction-scandium precipitation process is repeated four times based on the scandium enrichment of the scandium-rich material. The process is then stopped, and the final scandium-rich material is obtained. The scandium recovery rate in this process is 99.1%.

[0037] S4 uses a 3 mol / L hydrochloric acid solution to dissolve the above-mentioned ultimate scandium-enriched material. The liquid-to-solid ratio is 2.5:1 (hydrochloric acid solution volume in ml : ultimate scandium-enriched material mass in g, water content 50%). The ferric ions in the obtained solution are fully reduced using reduced iron powder at a rate of 0.3 g / L solution. After complete reduction, the solution is filtered to obtain filtrate and residue. The scandium leaching rate in this process is 99.6%. The obtained residue is returned to the reduction process, and then potassium dihydrogen phosphate is used to remove zirconium from the reduced solution at a rate of 0.4 g / L solution. After filtration, zirconium phosphate and impurity removal solution are obtained. Before removing zirconium, potassium dihydrogen phosphate is prepared into a solution. The zirconium precipitation rate in this process is 99.93%, and the scandium precipitation rate is <0.01%.

[0038] S5 uses a multi-stage countercurrent extraction process with a composite extractant to extract scandium ions from the above-mentioned impurity-removing solution. The extractant consists of 10% P2O4, 2.5% TBP, 2.5% Cyanex 3O2, and 85% sulfonated kerosene. The volume ratio of the composite extractant in the organic phase to the aqueous phase is 1:1. The number of countercurrent extraction stages is 2, the extraction temperature is 20℃, the single-stage extraction time is 6 min, the phase separation time is 2 min, the extraction equipment is a hydrocyclone extractor, and the phase separation time between the organic phase and the aqueous phase is 2 min. After phase separation, a scandium-loaded organic phase and raffinate are obtained. The scandium extraction rate in this process reaches 99.99%, and the extraction rates of other impurity elements are all <0.01%.

[0039] S6 used a sulfuric acid-hydrogen peroxide composite acid solution to elute S5 and obtain residual metallic impurities of iron, magnesium, calcium, manganese, titanium, and zirconium from the scandium-loaded organic phase. The sulfuric acid concentration was 20%, the hydrogen peroxide concentration was 1 mol / L, the volume ratio of the loaded organic phase to the aqueous phase was 1:1, the countercurrent elution impurity removal stage was 3, the temperature was 30℃, the elution time was 10 min, and the phase separation time was 1 min. In this process, the scandium recovery rate was 99.98%, and the removal rates of other impurity elements were all >95%.

[0040] S7 uses sodium oxalate with a mass concentration of 1.5 mol / L to perform multi-stage countercurrent back-extraction on the eluted scandium-loaded organic phase. During back-extraction, the volume ratio of the loaded organic phase to the sodium oxalate solution is 1:1, the number of back-extraction stages is 2, the back-extraction temperature is 30℃, and the phase separation time is 5 min. After phase separation and filtration, scandium oxalate is obtained with a scandium back-extraction rate of 99.2%. Scandium oxalate is washed with oxalic acid solution with a concentration of 0.5 mol / L. During washing, the liquid-solid ratio is oxalic acid solution volume (ml): scandium oxalate (wet material) weight (g) = 1:1, and the number of countercurrent washing stages is 3. The washed and filtered scandium oxalate is then calcined. During calcination, the temperature is increased to 105℃ at a rate of 8℃ / min and held at this temperature until the moisture content is 2.6%. The temperature is then increased to 850℃ at a rate of 25℃ / min and held at this temperature for 5 h. Finally, scandium oxide with a purity ≥99.97% is obtained.

[0041] Matters not covered in this invention are common knowledge.

[0042] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A method for extracting scandium from scandium-containing solid waste generated during titanium extraction via chlorination, characterized in that, The method includes the following steps: S1 uses water to pulp and dissolve scandium-containing solid waste with a scandium content of 290 g / t. The liquid-to-solid ratio during dissolution is water volume (ml): scandium-containing solid waste mass (g) = 3:

1. After filtration, a scandium-containing leachate with a pH of 0.9 and residue are obtained. The residue is then washed countercurrently with water whose pH is adjusted to 2.1 using hydrochloric acid. The liquid-to-solid ratio during washing is water volume (ml): residue mass (g) = 2:

1. The washing is performed 4 times. After filtration, washed residue and wash water are obtained. The wash water is recycled for pulping and leaching. S2 adjusts the pH of the leachate obtained in step S1 to 0.4 with a 3 mol / L hydrochloric acid solution. Iron powder is used to reduce the trivalent iron and hexavalent chromium in the leachate at a concentration of 3 g / L. The reduction temperature is 60°C. The filtrate and filter residue are obtained by filtration. The filter residue is returned to the reduction process. The pH of the filtrate is adjusted to 4.7 with a 10% NaOH solution. The system temperature is 60°C. After filtration, the residual liquid and scandium-containing precipitate are obtained. S3 uses 5 mol / L hydrochloric acid solution to dissolve the scandium-containing precipitate obtained in step S2. The liquid-to-solid ratio is 2.5:1 (volume of hydrochloric acid solution in ml) : mass of scandium-containing precipitate with 50% water content in g). The ferric ions in the obtained solution are fully reduced using iron powder at a concentration of 0.3 g / L solution. After complete reduction, the solution is filtered to obtain filtrate and residue. The residue is returned to the reduction process. The pH of the filtrate is adjusted to 4.0 using 15% NaOH solution. The remaining liquid and scandium-rich material are obtained by filtration. The acid leaching-reduction-scandium precipitation process is repeated 4 times according to the scandium enrichment of the scandium-rich material. The acid leaching-reduction-scandium precipitation process is then stopped. S4 uses a 3 mol / L hydrochloric acid solution to dissolve the final scandium-rich material obtained in step S3. The liquid-to-solid ratio is 2.5:1 (volume of hydrochloric acid solution in ml) : mass of the final scandium-rich material with 50% water content in g). The ferric ions in the obtained solution are fully reduced using iron powder at a rate of 0.3 g / L·solution. After complete reduction, the solution is filtered to obtain filtrate and residue. The residue is returned to the reduction process. Then, potassium dihydrogen phosphate is used to remove zirconium from the reduced solution at a rate of 0.4 g / L·reduced solution. After filtration, zirconium phosphate and impurity removal solution are obtained. Before removing zirconium, potassium dihydrogen phosphate is prepared into a solution. S5 uses a multi-stage countercurrent extraction process with a composite extractant to extract scandium ions from the impurity-removing solution obtained in step S4. The extractant consists of 10% P2O4, 2.5% TBP, 2.5% Cyanex3O2, and 85% sulfonated kerosene by volume. The volume ratio of the composite extractant in the organic phase to the aqueous phase is 1:

1. The number of countercurrent extraction stages is 2, the extraction temperature is 20℃, the single-stage extraction time is 6 min, the phase separation time is 2 min, the extraction equipment is a hydrocyclone extractor, and the phase separation time between the organic phase and the aqueous phase is 2 min. After phase separation, a scandium-loaded organic phase and raffinate are obtained. S6 uses a sulfuric acid-hydrogen peroxide composite acid solution to elute the residual metal impurities in the scandium-loaded organic phase obtained from S5. The hydrogen peroxide concentration is 1 mol / L, the volume ratio of the loaded organic phase to the aqueous phase is 1:1, the countercurrent elution impurity removal stage is 3, the temperature is 30℃, the elution time is 10 min, and the phase separation time is 1 min. S7 uses sodium oxalate with a mass concentration of 1.5 mol / L to perform multi-stage countercurrent back-extraction on the eluted scandium-loaded organic phase. During back-extraction, the volume ratio of the loaded organic phase to the sodium oxalate solution is 1:1, the number of back-extraction stages is 2, the back-extraction temperature is 30℃, and the phase separation time is 5 min. After phase separation and filtration, scandium oxalate is obtained. Scandium oxalate is washed with oxalic acid solution with a concentration of 0.5 mol / L. During washing, the liquid-solid ratio is oxalic acid solution volume (ml): scandium oxalate wet material weight (g) = 1:1, and the number of countercurrent washing stages is 3. The washed and filtered scandium oxalate is then calcined. During calcination, the temperature is increased to 105℃ at a rate of 8℃ / min and held at this temperature to dry the precipitate until its moisture content is 2.6%. The temperature is then increased to 850℃ at a rate of 25℃ / min and held at this temperature for 5 h. Finally, scandium oxide with a purity ≥99.97% is obtained.

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