A method for recovering scandium from a fused salt chlorination dusting residue

Abstract

The application discloses a method for recovering scandium from a molten salt chlorination dust collection residue, which comprises the following steps: water immersion is performed on the molten salt chlorination dust collection residue to obtain a leaching solution, scandium in the leaching solution is precipitated by using an alkali liquor containing a strong oxidizing substance, a scandium-rich residue is obtained, the scandium-rich residue is subjected to high-temperature conversion and fine grinding, and then the scandium is leached by using a sulfuric acid / hydrochloric acid-phosphoric acid solution, a scandium-rich liquid is obtained, scandium in the scandium-rich liquid is countercurrently extracted by using a composite extractant, a loaded organic phase and a raffinate are obtained, residual impurities in the loaded organic phase are eluted by using a hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid mixed solution, and scandium in the eluted loaded organic phase is subjected to multistage countercurrently reverse extraction by using an alkali liquor, scandium hydroxide with an impurity content less than 1% is obtained, the scandium hydroxide is dissolved by using hydrochloric acid, precipitated by using oxalic acid and high-temperature roasted, and finally, scandium oxide with a purity greater than 99.9% is obtained. The method is convenient to operate, simple in technological process, low in production cost, good in environmental protection benefit, easy to realize industrialization, and can efficiently recover the valuable element scandium in the molten salt chlorination dust collection residue.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a method for recovering scandium from molten salt chlorination dust collection residue. Background Technology

[0002] Scandium is an important rare earth element, and its oxides and alloys are attracting increasing attention due to their promising applications in aerospace, electric light source materials, and clean energy, as well as their scarcity. Currently, scandium resources are mainly found in waste acid from the sulfuric acid process for titanium dioxide production, dust collected during the chlorination of high-titanium slag, tungsten slag, red mud from the alumina industry, and hydrochloric acid waste liquid from the zirconium oxychloride production process. Among these, the dust collected during the molten salt chlorination process for titanium extraction contains a certain amount of valuable scandium, primarily in the form of a soluble salt. Molten salt chlorination and boiling chlorination are the two main methods for producing titanium tetrachloride, with molten salt chlorination accounting for 40% of the global annual production. Fluidized bed chlorination requires high-quality titanium slag raw materials (Ca+Mg<1.0%) and produces less pollution, while molten salt chlorination has lower requirements for raw materials (it is also suitable for titanium slag raw materials with high calcium and magnesium content), but produces more pollution. There is no economically effective treatment technology for pollutants such as molten salt chlorination dust slag emitted during the production process, both domestically and internationally. They are all treated by mixing with lime and then dumping in wasteland or landfilling in professional slag yards, which wastes valuable scandium resources.

[0003] Therefore, there is a need in the prior art to improve the methods for recovering scandium from molten salt chlorination dust collection residue. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for recovering scandium from molten salt chlorination dust collection residue. This method is easy to operate, has a simple process flow, low production cost, good environmental benefits, and is easy to industrialize. It can efficiently recover valuable element scandium from molten salt chlorination dust collection residue.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for recovering scandium from molten salt chlorination dust collection residue, comprising the following steps:

[0006] a. The molten salt chlorination dust collector residue is leached with water to obtain leachate and first leaching residue. The first leaching residue is washed and recycled as a titanium extraction raw material. The wash water is recycled for leaching the molten salt chlorination dust collector residue.

[0007] b. Use an alkaline solution containing strong oxidizing substances to precipitate scandium in the leachate to obtain scandium-rich residue and brine. The brine is then recovered as a raw material for the preparation of sodium, magnesium, and calcium salts.

[0008] c. After high-temperature conversion and fine grinding, scandium-rich residue is leached with sulfuric acid / hydrochloric acid-phosphoric acid to obtain scandium-rich solution and second leaching residue. The second leaching residue is recycled as raw material for manganese extraction and iron smelting.

[0009] d. Scandium in the scandium-rich solution was extracted using a composite extractant via countercurrent cyclone extraction to obtain a loaded organic phase and raffinate;

[0010] e. Use a hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid mixed solution to elute residual impurities such as titanium, manganese, calcium, zirconium, iron, magnesium, and vanadium in the supported organic phase, with an elution stage number ≥ 1;

[0011] f. Scandium in the eluted loaded organic phase is subjected to multi-stage countercurrent cyclone back-extraction using alkaline solution to obtain scandium hydroxide with an impurity content of <1%. The scandium hydroxide is then dissolved in hydrochloric acid, precipitated with oxalic acid, and calcined at high temperature to finally obtain scandium oxide with a purity of >99.9%.

[0012] In some embodiments, in step a, the scandium content in the molten salt chlorination dust collector is 10-150 g / t, the liquid-to-solid ratio (volume:mass) during water leaching is (1-10):1, the solution pH is kept <2 during leaching to prevent scandium ions from hydrolyzing and entering the solid leaching residue, the leaching process is strengthened by stirring, and the leaching time is 2-5 h to ensure that scandium is fully leached out, the washing water is kept at pH <2 to prevent scandium ion hydrolysis, and the first leaching residue is washed until the salt content (mass percentage) is <0.05%.

[0013] In some embodiments, in step b, the alkaline solution is a highly oxidizing, alkaline waste brine produced by the purification of molten salt chlorination tail gas or a waste liquid absorbed by chlor-alkali chemical tail gas. The alkaline concentration in the alkaline solution is 5% to 15%, and the alkaline solution and the leachate are mixed at a ratio of (1 to 1.5): 1. The reaction time is 1.5 to 3 hours.

[0014] In some embodiments, in step c, the scandium-rich slag is calcined at 700–900°C for 3–6 hours to transform into oxides. The calcined product is then ground to a particle size of less than 250 mesh and leached with sulfuric acid / hydrochloric acid-phosphoric acid. The sulfuric acid concentration is 1–5 mol / L, the hydrochloric acid concentration is 1–5 mol / L, and the phosphoric acid concentration is 0.5–2 mol / L. The leaching time is 2–5 hours to obtain a scandium-rich solution with low impurity content and a second leaching residue. The second leaching residue includes elements such as titanium, manganese, zirconium, and iron.

[0015] In some embodiments, in step d, the composite extractant comprises, by volume percentage: TBP (5%–30%), P204 (5%–30%), cyanex572 (0%–10%), and 260# solvent oil (50%–90%). The volume ratio of the organic phase composite extractant to the aqueous phase reduced leachate during extraction is 1:(1–30). The extraction equipment is an acid and alkali resistant cyclone extractor with an extraction stage ≥1.

[0016] In some embodiments, in step e, the concentration of sulfuric acid or hydrochloric acid in the hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid / phosphate mixed solution is 1-5 mol / L, the concentration of hydrogen peroxide is 1-2 mol / L, the amount of phosphoric acid or phosphate added is 1-1.5 times the theoretical amount required to completely remove titanium and zirconium from the organic phase, the elution time is 10-30 min, and the elution stage number is ≥1.

[0017] In some embodiments, in step f, the alkaline solution is NaOH solution or ammonia water with a concentration of 1.5-3 mol / L. During back-extraction, the volume ratio of the loaded organic phase to the alkaline solution is 1:(0.5-2). The back-extraction equipment is an acid- and alkali-resistant cyclone extractor with ≥1 back-extraction stage. The back-extraction product is dissolved in hydrochloric acid to remove silicon-containing impurities with a concentration of 1-5 mol / L. Then, scandium ions are precipitated with oxalic acid or sodium oxalate. The amount of oxalic acid or sodium oxalate added is 1-1.5 times the theoretical mass required to completely precipitate scandium ions. After centrifugation, filtration, and dehydration, the precipitate is calcined at 600-900℃ for 3-6 hours for dehydration and transformation, finally obtaining a scandium oxide product with a purity of ≥99.9%.

[0018] The present invention has at least the following beneficial technical effects:

[0019] This invention provides a method for recovering scandium from molten salt chlorination dust collector residue. The method involves repeatedly leaching the molten salt chlorination dust collector residue with water, alkali, and acid, followed by extraction, elution, and back-extraction to remove impurities and purify the scandium element. The products from the recovery process can be recycled or further applied. The recovery process is environmentally friendly, efficient, low-cost, and easy to implement for industrial-scale recycling. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an embodiment of the method for recovering scandium from molten salt chlorination dust collection residue provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0023] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0024] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] like Figure 1 The present invention illustrates a method for recovering scandium from molten salt chlorination dust collection residue, comprising the following steps:

[0026] a. The molten salt chlorination dust collector residue is leached with water to obtain leachate and first leaching residue. The first leaching residue is washed and recycled as a titanium extraction raw material. The wash water is recycled for leaching the molten salt chlorination dust collector residue.

[0027] b. Use an alkaline solution containing strong oxidizing substances to precipitate scandium in the leachate to obtain scandium-rich residue and brine. The brine is then recovered as a raw material for the preparation of sodium, magnesium, and calcium salts.

[0028] c. After high-temperature conversion and fine grinding, scandium-rich residue is leached with sulfuric acid / hydrochloric acid-phosphoric acid to obtain scandium-rich solution and second leaching residue. The second leaching residue is recycled as raw material for manganese extraction and iron smelting.

[0029] d. Scandium in the scandium-rich solution was extracted using a composite extractant via countercurrent cyclone extraction to obtain a loaded organic phase and raffinate;

[0030] e. Use a hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid mixed solution to elute residual impurities such as titanium, manganese, calcium, zirconium, iron, magnesium, and vanadium in the supported organic phase, with an elution stage number ≥ 1;

[0031] f. Scandium in the eluted loaded organic phase is subjected to multi-stage countercurrent cyclone back-extraction using alkaline solution to obtain scandium hydroxide with an impurity content of <1%. The scandium hydroxide is then dissolved in hydrochloric acid, precipitated with oxalic acid, and calcined at high temperature to finally obtain scandium oxide with a purity of >99.9%.

[0032] Further, in step a, the scandium content in the molten salt chlorination dust collector residue is 10-150 g / t, and the water leaching liquid-to-solid ratio (volume:mass) is (1-10):1. During the leaching process, the solution pH must be maintained <2 to prevent scandium ions from hydrolyzing and entering the solid phase leaching residue. If the pH does not meet the requirements, acid can be added appropriately to adjust the pH to <2. Stirring should be strengthened during the leaching process, and the leaching time is 2-5 hours to ensure that scandium is fully leached. The washing water used during washing must also be kept at pH <2 to prevent scandium ion hydrolysis. The washing water can be returned to the water leaching process. The leaching residue is washed until the salt content (mass percentage) is <0.05%. The washed leaching residue can be further recycled for titanium recovery. The washing water can be used for recycling or as a leaching agent for the next leaching of the molten salt chlorination dust collector residue, depending on the amount of washing water. The washing water is reused throughout the process and is not discharged. The leaching liquid is used as a raw material for scandium extraction.

[0033] Further, in step b, the alkaline solution containing strong oxidizing substances can be the strong oxidizing and alkaline waste brine produced by the purification of molten salt chlorination tail gas or the waste liquid absorbed by chlor-alkali chemical tail gas. To ensure that the alkali concentration in the strong oxidizing and alkaline solution is 5% to 15%, caustic soda can be added appropriately. The alkaline solution and the above leachate are mixed at (1 to 1.5): 1 and reacted for 1.5 to 3 hours. The solution is filtered to obtain scandium-rich residue and brine. The brine can be recovered as a raw material for the preparation of sodium salt, magnesium salt and calcium salt, and the scandium-rich residue is used as a raw material for the next step of scandium extraction.

[0034] Further, in step c, the scandium-rich slag is roasted at 700–900℃ for 3–6 hours. After roasting, it is basically transformed into oxides. The purpose of roasting is to convert the compounds of elements such as iron, manganese, titanium, and zirconium into oxides that are insoluble, slightly soluble, or slowly soluble in dilute acid at room temperature, so as to facilitate the separation of scandium from impurities during subsequent dilute acid leaching at room temperature. The roasted product needs to be ground to a particle size range of less than 250 mesh, and then leached with sulfuric acid / hydrochloric acid-phosphoric acid, with a sulfuric acid concentration of 1–5 mol / L or hydrochloric acid of 1–5 mol / L and phosphoric acid of 0.5–2 mol / L, for a leaching time of 2–5 hours, to obtain a scandium-rich solution with low impurity content and a leaching residue containing the main impurities such as titanium, manganese, zirconium, and iron. This leaching residue can be reused as a raw material for manganese extraction and iron smelting.

[0035] Further, in step d, the composite extractant includes the following components by volume percentage: TBP (5%–30%) + P2O4 (5%–30%) + cyanex572 (0%–10%) + 260# solvent oil (50%–90%). Before extraction, the organic phase of the composite extractant does not need to be saponified. The increased acidity during extraction has virtually no effect on the extraction of scandium ions but helps to inhibit the extraction of other ions. During extraction, the volume ratio of the organic phase composite extractant to the aqueous phase leachate after reduction is 1:(1–30). The extraction equipment is an acid- and alkali-resistant hydrocyclone extractor. The model and operating parameters of the hydrocyclone extractor can be adjusted according to the feed solution conditions, and the number of extraction stages is ≥1.

[0036] Further, in step e, impurities such as titanium, manganese, calcium, zirconium, iron, magnesium, and vanadium in the loaded organic phase are eluted with a hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid / phosphate mixed solution. The concentration of sulfuric acid or hydrochloric acid is 1-5 mol / L, the concentration of hydrogen peroxide is 1-2 mol / L, the amount of phosphoric acid or phosphate added is 1-1.5 times the theoretical amount required to completely remove titanium and zirconium from the organic phase, the elution time is 10-30 min, and the elution stage number is ≥1.

[0037] Further, in step f, the alkaline solution used for back-extraction can be NaOH solution or ammonia water with a concentration of about 1.5 to 3 mol / L. The volume ratio of the loaded organic phase to the alkaline solution during back-extraction is 1:(0.5 to 2). The back-extraction equipment is an acid and alkali resistant hydrocyclone extractor (which is beneficial for the separation of back-extracted material). The model and operating parameters of the hydrocyclone extractor can be adjusted according to the feed liquid conditions. The number of back-extraction stages is ≥1. The back-extraction product is post-processed to obtain scandium oxide. The post-processing includes hydrochloric acid dissolution, oxalic acid precipitation, and high-temperature calcination. Specifically, the back-extraction product is dissolved in hydrochloric acid at a concentration of 1–5 mol / L. The hydrochloric acid dissolution process removes silicon-containing impurities. The scandium-containing impurity-removed solution is then precipitated with oxalic acid or sodium oxalate. The amount of oxalic acid and sodium oxalate added is 1–1.5 times the theoretical mass required for complete precipitation of scandium ions. After centrifugation, filtration, and dehydration, the precipitate is calcined at 600–900℃ for 3–6 hours for further dehydration and transformation, finally obtaining scandium oxide with a purity ≥99.9%.

[0038] The following example, using molten salt chlorination dust collector residue obtained from a certain sampling, will be used to illustrate in detail the method for recovering scandium from molten salt chlorination dust collector residue disclosed in the embodiments of the present invention.

[0039] Example 1

[0040] The main components of the molten salt chlorination dust collector obtained from the sampling are shown in Table 1.

[0041] Table 1. Main components of the molten salt chlorination dust collected from samples.

[0042]

[0043] The molten salt chlorination dust collector residue was leached with water at a liquid-to-solid ratio of 5:1, with enhanced stirring during the leaching process. The leaching time was 4 hours, and the scandium leaching rate was approximately 90%, yielding a leachate with a pH of approximately 1.2. Scandium in the leachate was then precipitated using highly oxidizing and alkaline wastewater generated from the molten salt chlorination tail gas purification process, with an alkali concentration adjusted to 10%. The alkali solution and leachate were mixed at a 1:1 ratio, and the reaction time was 2 hours. The final pH was controlled at approximately 7 to ensure complete scandium ion precipitation, resulting in scandium-rich residue. In this process, almost all scandium ions entered the precipitate. The scandium-rich residue was then calcined at 750℃. High-temperature conversion and calcination for 5 hours yielded oxides, which were then finely ground to a particle size of less than 300 mesh. The oxides were then leached for 3 hours with a mixture of 3 mol / L sulfuric acid and 1 mol / L phosphoric acid to obtain a scandium-rich solution. The scandium leaching rate was approximately 96%, while the leaching rates of the main impurity elements were <1% for titanium, <2% for manganese, <1% for zirconium, and <5% for iron. A composite extractant consisting of TBP (5%), P204 (20%), cyanex572 (5%), and 260# solvent oil (70%) was used in a non-saponifiable process. Scandium in a scandium-rich solution was extracted directly using countercurrent cyclone extraction. Compared to a 1:10 extraction ratio, the scandium extraction rate reached 99.5%, while the extraction rates of other impurities in the scandium-containing solution were only about 0.1% to 1%, yielding a loaded organic phase and raffinate. Residual impurities in the loaded organic phase were eluted using a hydrogen peroxide-sulfuric acid-phosphoric acid mixed solution, with a sulfuric acid concentration of 4.5 mol / L, a hydrogen peroxide concentration of 1.3 mol / L, and the amount of phosphoric acid added being 1.1 times the theoretical amount required to completely remove titanium and zirconium from the organic phase. The elution time was 20 min, and the elution stage was 3. During this process, the scandium... The loss rate was approximately 0.3%. The supported organic phase was subjected to multi-stage countercurrent cyclone back-extraction with a 3 mol / L NaOH solution at a 1:1 ratio to obtain scandium hydroxide with an impurity content of <1%. The scandium back-extraction rate in this process was approximately 99%. The scandium hydroxide was then completely dissolved in 1 mol / L hydrochloric acid and precipitated with sodium oxalate to obtain a precipitate. The amount of sodium oxalate added was 1.1 times the theoretical mass required for complete precipitation of scandium ions. The precipitate was centrifuged, filtered, and dehydrated before being calcined at 850℃ for 5 hours to finally obtain scandium oxide with a purity of 99.92%.

[0044] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0045] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0046] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0047] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for recovering scandium from a fused salt chlorination dusting residue, characterized by, The method comprises the following steps: a. water leaching of the molten salt chlorination dust collection residue to obtain a leaching solution and a first leaching residue, the first leaching residue is recycled as a raw material for titanium extraction after washing, and the washing water is recycled for leaching of the molten salt chlorination dust collection residue; b. precipitation of scandium in the leaching solution by using an alkali liquor to obtain a scandium-rich residue and brine, the brine is recycled as a raw material for preparation of sodium salt, magnesium salt and calcium salt, the alkali liquor is a strong oxidizing and alkaline waste brine generated by purification of molten salt chlorination tail gas or a waste liquid absorbed from chlor-alkali chemical tail gas, and the alkali concentration in the alkali liquor is 5% to 15%; c. high-temperature conversion and fine grinding of the scandium-rich residue, and then leaching of scandium by using sulfuric acid / hydrochloric acid-phosphoric acid to obtain a scandium-rich liquid and a second leaching residue, the second leaching residue is recycled as a raw material for manganese extraction and iron smelting; d. countercurrent cyclonic extraction of scandium in the scandium-rich liquid by using a composite extractant to obtain a loaded organic phase and a raffinate; e. elution of residual titanium, manganese, calcium, zirconium, iron, magnesium and vanadium impurities in the loaded organic phase by using a hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid mixed solution, and the elution grade is greater than or equal to 1; f. multistage countercurrent cyclonic stripping of scandium in the loaded organic phase after elution by using an alkali liquor to obtain scandium hydroxide with an impurity content less than 1%, the scandium hydroxide is dissolved by hydrochloric acid, precipitated by oxalic acid and high-temperature roasted, and finally, scandium oxide with a purity greater than 99.9% is obtained. In step d, the composite extractant comprises, by volume percentage, TBP: 5% to 30%, P204: 5% to 30%, cyanex572: 0% to 10%, and 260# solvent oil: 50% to 90%, the volume ratio of the organic phase composite extractant to the reduced leaching solution in water phase is 1: (1 to 30) during extraction, the extraction equipment is an acid-alkali-resistant cyclonic extractor, and the extraction grade is greater than or equal to 1.

2. The method of recovering scandium from a fused salt chlorination dust according to claim 1, characterized by, In step a, the scandium content in the molten salt chlorination dust collection residue is 10 to 150 g / t, the liquid-solid ratio is volume: mass (1 to 10): 1 during water leaching, the solution pH is kept less than 2 during the leaching process to avoid hydrolysis of scandium ions into the solid leaching residue, the leaching process is strengthened by stirring, the leaching time is 2 to 5 hours to ensure sufficient leaching of scandium, and the water used for washing is kept at pH less than 2 to prevent hydrolysis of scandium ions, and the first leaching residue is washed until the salt content is less than 0.05% by mass percentage.

3. The method of recovering scandium from a fused salt chlorination dust according to claim 1, characterized by, In step b, the alkali liquor is mixed with the leaching solution at a ratio of (1 to 1.5): 1, and the reaction time is 1.5 to 3 hours.

4. The method of recovering scandium from a fused salt chlorination dust according to claim 1, characterized by, In step c, the scandium-rich residue is roasted at a high temperature of 700 to 900 DEG C for high-temperature conversion, the roasting time is 3 to 6 hours, the roasted product is ground to a particle size range of 250 mesh or less, and then leached by sulfuric acid / hydrochloric acid-phosphoric acid, the sulfuric acid concentration is 1 to 5 mol / L, the hydrochloric acid concentration is 1 to 5 mol / L, the phosphoric acid concentration is 0.5 to 2 mol / L, the leaching time is 2 to 5 hours, a scandium-rich liquid with a low impurity content and a second leaching residue are obtained, and the second leaching residue contains titanium, manganese, zirconium and iron elements.

5. The method of recovering scandium from a fused salt chlorination dust according to claim 1, characterized in that, In step e, the concentration of sulfuric acid or hydrochloric acid in the hydrogen peroxide-sulfuric acid / hydrochloric acid-phosphoric acid mixed solution is 1-5 mol / L, the concentration of hydrogen peroxide is 1-2 mol / L, the amount of phosphoric acid added is 1-1.5 times the theoretical amount required for complete removal of titanium and zirconium in the organic phase, the elution time is 10-30 min, and the elution stage is ≥1.

6. The method of recovering scandium from a fused salt chlorination dust according to claim 1, wherein In step f, the alkali solution is NaOH solution or ammonia water, and the concentration is 1.5-3 mol / L; the volume ratio of the loaded organic phase to the alkali solution during back extraction is 1:(0.5-2); the back extraction equipment is an acid and alkali resistant hydrocyclone extractor; the back extraction stage is ≥1; the back extraction product is dissolved by hydrochloric acid to remove silicon impurities, the concentration of the hydrochloric acid is 1-5 mol / L; and scandium ions are precipitated by oxalic acid or sodium oxalate, the amount of the oxalic acid or sodium oxalate added is 1-1.5 times the theoretical amount required for complete precipitation of scandium ions; the precipitate is centrifuged, filtered and dehydrated, and then calcined at 600-900 ℃ for 3-6 h for dehydration and transformation, and finally, scandium oxide products with a purity of ≥99.9% are obtained.

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