A method for selectively producing telluric acid

Abstract

The application discloses a method for selectively preparing telluric acid, which comprises the following steps: mixing tellurium dioxide material with a sodium hydroxide solution to perform an alkali leaching reaction, gradiently adding a sulfuric acid solution to perform a neutralization reaction, mixing obtained tellurous acid precipitate with a hydrogen peroxide solution to perform an oxidation reaction, mixing obtained telluric acid solution with concentrated nitric acid, stirring, precipitating telluric acid, placing obtained telluric acid precipitate in distilled water to perform recrystallization, filtering, drying, and obtaining telluric acid products. According to the method, the tellurium dioxide material is used as a raw material, a synergistic process of selective leaching, directional precipitation, mild oxidation, selective tellurium precipitation and recrystallization is adopted, high-purity telluric acid can be efficiently prepared, the purification of tellurium and the preparation of telluric acid can be integrally completed, the traditional synthesis path of telluric acid, i.e., 'purification first and then synthesis', is overturned, and the method has the characteristics of low cost, simple process, high preparation efficiency, high product purity, high yield, environmental friendliness and the like, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology and relates to a method for selectively preparing telluric acid. Background Technology

[0002] The existing technologies for preparing telluric acid (molecular formula H6TeO6) suffer from several major drawbacks that restrict its large-scale application: (1) Limitations of raw material routes: Traditional methods rely on high-priced raw materials such as pure tellurium powder and barium tellurate (purity ≥99%), with raw material costs accounting for more than 60% of the total cost. Moreover, the sources are scarce, resulting in high production costs for telluric acid.

[0003] (2) Indirectness and complexity of the process: In the existing technology, crude tellurium slag is used as raw material to recover metallic tellurium or refined tellurium. However, the methods involved cannot directly obtain telluric acid and have problems such as harsh reaction conditions, incomplete removal of impurities, and serious secondary pollution. At the same time, the method of recovering metallic tellurium or refined tellurium using crude tellurium slag as raw material also has problems such as lengthy process (more than 8 steps), large tellurium loss rate (more than 15%), and high wastewater production.

[0004] (3) Contradiction between purity and yield: The purity of telluric acid products prepared by existing methods is ≤98%, the impurity content is too high, and the yield is less than 70%, which is difficult to meet the strict requirements of high-end fields such as semiconductor materials and biomedicine for impurity content (≤0.005%).

[0005] Therefore, developing a telluric acid preparation technology that is low-cost, simple, efficient, produces high-purity products, has high yield, and is environmentally friendly has significant economic and social value.

[0006] For the reasons stated above, this invention is proposed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for selectively preparing telluric acid that is low in cost, simple in process, high in preparation efficiency, high in product purity, high in yield, and environmentally friendly, in order to address the shortcomings of the existing technology.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for selectively preparing telluric acid includes the following steps: (1) The tellurium dioxide material is mixed with sodium hydroxide solution for alkaline leaching reaction to obtain sodium tellurite solution; (2) A neutralization reaction was carried out by gradually adding sulfuric acid solution to sodium tellurite solution to obtain tellurite precipitate; (3) The tellurite precipitate was mixed with hydrogen peroxide solution to carry out an oxidation reaction, resulting in a telluric acid solution; (4) Mix the telluric acid solution with concentrated nitric acid, stir, and telluric acid precipitate will be obtained; (5) The telluric acid precipitate was placed in distilled water for recrystallization, filtered, and dried to obtain the telluric acid product.

[0009] The above method is further improved in step (2) by adding sulfuric acid solution in a gradient manner as follows: first, add sulfuric acid solution at an acid addition rate of 5 mL / min to 10 mL / min to adjust the pH of the system to 7.0 to 8.0, and then add sulfuric acid solution at an acid addition rate of 2 mL / min to 5 mL / min to adjust the pH of the system to 6.0 to 7.0; the mass concentration of the sulfuric acid solution is 10% to 70%; and the neutralization reaction time is 0.1 h to 0.6 h.

[0010] In a further improvement to the above method, in step (2), the mass concentration of the sulfuric acid solution is 20% to 30%; the neutralization reaction time is 0.2 h to 0.5 h; after the neutralization reaction is completed, the method further includes: filtering the product of the neutralization reaction, collecting the precipitate, washing the precipitate with distilled water, the washing is performed 2 to 4 times, to obtain tellurite precipitate; the amount of distilled water used is 1 to 2 times that of the precipitate.

[0011] In a further improvement to the above method, in step (3), the mass ratio of the hydrogen peroxide solution to the tellurite precipitate is 3.0 to 5.0:1; the mass concentration of the hydrogen peroxide solution is 10% to 50%; the oxidation reaction is carried out at a temperature of 80°C to 110°C; and the oxidation reaction takes 0.1 h to 1 h.

[0012] In a further improvement to the above method, in step (3), the mass concentration of the hydrogen peroxide solution is 20% to 40%; the oxidation reaction is carried out at a temperature of 90°C to 100°C; and the oxidation reaction takes 0.5 to 0.6 hours.

[0013] In a further improvement to the above method, in step (4), the amount of concentrated nitric acid added is 1 to 1.5 times that of the telluric acid solution; the mass concentration of the concentrated nitric acid is 40% to 70%; and the stirring time is 0.2 h to 0.5 h.

[0014] In a further improvement to the above method, in step (4), the mass concentration of the concentrated nitric acid is 50% to 70%; and the stirring time is 0.3 h to 0.4 h.

[0015] In a further improvement to the above method, in step (1), the ratio of tellurium dioxide material to sodium hydroxide solution is 0.6 g~1.4 g∶1 mL; the tellurium dioxide material is waste residue containing tellurium dioxide; the purity of the tellurium dioxide material is ≥50%; the particle size of the tellurium dioxide material is ≤500 μm; the concentration of the sodium hydroxide solution is 300 g / L~700 g / L; the alkaline leaching reaction is carried out at a temperature of 25℃~35℃; the alkaline leaching reaction time is 0.5 h~1 h; after the alkaline leaching reaction is completed, the product is filtered using a ceramic membrane to remove the filter residue and obtain sodium tellurite solution; the filtration accuracy of the ceramic membrane is 0.1 μm~1.0 μm.

[0016] The above method is further improved in step (5), wherein the recrystallization is carried out as follows: firstly, the first crystallization is carried out at a temperature of 100℃~110℃ for 1 h~2 h, and then the second crystallization is carried out at a temperature of 90℃~95℃ for 1 h~2 h; the drying is carried out at a temperature of 60℃~80℃; the drying time is 2 h~4 h; the mother liquor generated during the recrystallization process is concentrated and then mixed with telluric acid precipitate for further recrystallization.

[0017] In a further improvement to the above method, in step (1), the ratio of tellurium dioxide material to sodium hydroxide solution is 0.8 g to 1.3 g: 1 mL; the particle size of tellurium dioxide material is 100 μm to 500 μm; and the concentration of sodium hydroxide solution is 400 g / L to 600 g / L.

[0018] In a further improvement to the above method, in step (5), the purity of the telluric acid product is ≥99%.

[0019] The method for selectively preparing telluric acid according to the present invention involves the following five core steps: (1) Selective leaching of tellurium: Tellurium dioxide material (such as crude tellurium dioxide slag, a by-product of smelting) is selected as raw material. By controlling the particle size of the raw material and the concentration of sodium hydroxide solution, the selective leaching of tellurium element is achieved, and sodium tellurite solution is generated. Most heavy metal impurities (Cu, Pb, As, etc.) remain in the leaching residue. The single leaching rate of tellurium can reach more than 95%.

[0020] (2) Directional neutralization and precipitation of tellurium: By precisely controlling the addition rate of sulfuric acid solution and the reaction pH value, tellurium acid is precipitated in a directional manner, effectively separating soluble impurities and ensuring that the purity of tellurium acid precipitation is ≥98%.

[0021] (3) Mild oxidation conversion: Hydrogen peroxide is used as a green oxidant to achieve efficient conversion of tellurite to telluric acid under mild temperature conditions of 80~110℃, with an oxidation conversion rate of ≥99%, avoiding equipment damage and safety risks caused by high temperature and high pressure.

[0022] (4) Selective tellurium precipitation purification: Taking advantage of the low solubility of telluric acid in concentrated nitric acid, deep separation of telluric acid from trace impurities is achieved, with a tellurium precipitation rate ≥90%.

[0023] (5) Recrystallization refining: Through a secondary recrystallization process and precise temperature-controlled drying, the purity of the product is further improved, and finally high-purity telluric acid with a purity of ≥99.5% is obtained.

[0024] Compared with conventional techniques, the method for selectively preparing telluric acid of this invention is innovative in the following aspects: (1) Product route innovation: In response to the indirect mode of "extracting tellurium first and then producing telluric acid" in the existing technology, this invention constructs an integrated direct preparation route of "selective leaching - directional precipitation - mild oxidation - selective precipitation of tellurium - recrystallization". The process is shortened from 8 to 10 steps in the existing technology to 5 steps, the tellurium loss rate is reduced to ≤8%, and telluric acid can be obtained directly without additional oxidation steps, improving the process efficiency by more than 40%.

[0025] (2) Innovation in impurity separation: For the complex system containing multiple heavy metal impurities such as Cu, Pb, As, Zn and Sn in crude tellurium slag, a three-stage synergistic impurity removal process of "alkali leaching to remove heavy metals + neutralization to remove soluble impurities + nitric acid precipitation to remove trace impurities" was designed, which solved the limitation of existing technologies that can only remove selenium impurities, and the total impurity removal rate is ≥96%.

[0026] (3) Green process innovation: Hydrogen peroxide is used as a green oxidant. No toxic or harmful gases are generated during the reaction process. Compared with conventional oxidant chloric acid (which is highly corrosive and easily produces toxic gases), the environmental friendliness is significantly improved. At the same time, nitric acid is recycled and reused, reagent consumption is reduced by more than 20%, and wastewater discharge is reduced by more than 30%.

[0027] (4) Parameter synergistic optimization innovation: By systematically optimizing process parameters such as "liquid-solid ratio-reaction temperature-reagent concentration-reaction time", the direct yield of telluric acid is stabilized at over 75.7%, which is 10-15 percentage points higher than the traditional process, and the product purity is increased to over 99.5%.

[0028] Compared with the prior art, the advantages of the present invention are as follows: To address the shortcomings of existing telluric acid preparation methods, such as high cost, complex processes, low efficiency, low product purity, low yield, and poor environmental friendliness, this invention creatively proposes a selective telluric acid preparation method. Using tellurium dioxide as raw material, a synergistic process of selective leaching, directional precipitation, mild oxidation, selective tellurium precipitation, and recrystallization is employed to achieve high-purity telluric acid production. Simultaneously, the purification of tellurium and the preparation of telluric acid are completed in an integrated manner, overturning the traditional "purification first, then synthesis" telluric acid synthesis route. This method features low cost, simple process, high efficiency, high product purity, high yield, and environmental friendliness, making it suitable for large-scale industrial production. Details are as follows: ① Raw material cost advantage: Using tellurium dioxide materials as raw materials, especially crude tellurium dioxide slag, a by-product of smelting, significantly reduces costs compared to pure tellurium powder, barium tellurate, and other raw materials. At the same time, it realizes the resource utilization of industrial waste residue, which is in line with the concept of green development.

[0029] ② Product advantages: Telluric acid purity ≥99.5%, up to 99.8%, and heavy metal impurities such as Cu, Pb, and As are all ≤0.005%, meeting the requirements of high-end fields such as semiconductor materials and biomedicine.

[0030] ③ Advantages in process efficiency: No high temperature and high pressure equipment is required (reaction temperature ≤110℃, normal pressure operation), equipment investment is reduced, the process flow is short and the operation is simple, making it suitable for large-scale industrial production.

[0031] ④ Environmental advantages: Processing 1,000 tons of coarse tellurium slag annually can reduce solid waste emissions by 1,000 tons and recover more than 500 tons of tellurium resources; the nitric acid recycling rate is ≥85%, and wastewater discharge is reduced by 30%, which meets environmental protection requirements. Attached Figure Description

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0033] Figure 1 This is a process flow diagram of selectively preparing telluric acid in Example 1 of the present invention.

[0034] Figure 2 The image shows the XRD pattern of the crude tellurium dioxide slag raw material used in Example 1 of this invention.

[0035] Figure 3 This is a photograph of the telluric acid product synthesized in Example 1 of the present invention.

[0036] Figure 4 The image shows the XRD pattern of the telluric acid product synthesized in Example 1 of this invention. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0038] In the following embodiments of the present invention, unless otherwise specified, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of two or more repeated experiments.

[0039] This invention provides a method for selectively preparing telluric acid, comprising the following steps: Tellurium dioxide material (such as crude tellurium dioxide slag) is mixed with sodium hydroxide solution, and after alkaline leaching, it is filtered to obtain sodium tellurite solution. Sulfuric acid solution is added to the sodium tellurite solution in a gradient to cause a neutralization reaction and directionally generate tellurite precipitate. The tellurite is mixed with hydrogen peroxide solution to oxidize and generate telluric acid solution. The telluric acid solution is mixed with concentrated nitric acid to generate telluric acid precipitate, which is then recrystallized with distilled water to obtain telluric acid.

[0040] In this invention, tellurium dioxide material (such as crude tellurium dioxide slag from smelting) is used as raw material. Tellurium purification and telluric acid preparation are integrated, proposing a new route for telluric acid preparation. Impurities in the raw material remain in the slag after alkaline leaching, or in the solution after neutralization, or in the solution after nitric acid precipitation. Through three simple filtrations, the impurities can be separated and telluric acid can be prepared, as detailed below: (1) Mix tellurium dioxide material (such as crude tellurium dioxide slag) with sodium hydroxide solution and carry out alkaline leaching reaction. Tellurium element is leached out to form sodium tellurite in the solution, while impurities remain in the alkaline leaching residue. The first filtration separates the impurities that are insoluble in alkali, and a transparent sodium tellurite solution is obtained.

[0041] (2) Add sulfuric acid solution to sodium tellurite solution to neutralize it and generate white tellurite precipitate. Impurities remain in the solution. Filter the solution a second time to separate the impurities and obtain tellurite precipitate.

[0042] (3) Mix the tellurite precipitate with hydrogen peroxide solution, heat and oxidize to produce telluric acid solution, precipitate telluric acid with concentrated nitric acid, and leave the impurities in the solution. Filter the solution for the third time to separate the impurities and obtain telluric acid precipitate. Recrystallize the telluric acid precipitate with distilled water to obtain telluric acid product.

[0043] The telluric acid prepared by this invention has a purity greater than 99% and a product yield of up to 75.7%. This method is low in cost, simple to operate, and suitable for large-scale preparation of telluric acid.

[0044] In this invention, the purity of the tellurium dioxide material (such as coarse tellurium dioxide slag) is greater than 50%, and the particle size is less than 500 micrometers.

[0045] In this invention, there is no particular limitation on the order of adding crude tellurium dioxide slag and sodium hydroxide solution. Preferredly, the crude tellurium dioxide slag is added to the sodium hydroxide solution under stirring conditions. There are no particular limitations on the stirring method in this invention.

[0046] In this invention, the concentration of sodium hydroxide solution is preferably 300-700 g / L, more preferably 400-600 g / L, and specifically, in the embodiments of this invention, 500 g / L can be used.

[0047] In this invention, the liquid-solid ratio of crude tellurium slag to sodium hydroxide solution is preferably 1:0.6 to 1.4, more preferably 1:0.8 to 1.3, and specifically, in the embodiments of this invention, 1:1 can be used.

[0048] In this invention, the mass concentration of the sulfuric acid solution is preferably 10% to 70%, more preferably 20% to 30%, and specifically, in the embodiments of this invention, 25% can be used.

[0049] In this invention, the mass concentration of hydrogen peroxide solution is preferably 10% to 50%, more preferably 20% to 40%, and specifically, in the embodiments of this invention, 30% can be used.

[0050] In this invention, the reaction temperature of the oxidation reaction is preferably 80-110 °C, and more preferably 90-100 °C.

[0051] In this invention, the mass concentration of concentrated nitric acid is preferably 40% to 70%, more preferably 60% to 70%, and specifically, in the embodiments of this invention, 68% can be used.

[0052] In this invention, the alkaline leaching reaction time is preferably 0.5 to 1 h, more preferably 0.5 to 0.6 h.

[0053] In this invention, the neutralization reaction time is preferably 0.1 to 0.5 h, more preferably 0.2 to 0.3 h.

[0054] In this invention, the oxidation reaction time is preferably 0.5 to 1 h, more preferably 0.5 to 0.6 h.

[0055] In this invention, the reaction time for nitric acid precipitation of tellurium is preferably 0.2 to 0.5 h, more preferably 0.3 to 0.4 h.

[0056] In this invention, the recrystallization temperature of telluric acid is preferably 90 ℃~110 ℃, more preferably 95 ℃~105 ℃. After recrystallization and cooling, telluric acid precipitates from the mother liquor and is filtered to obtain the telluric acid product. The obtained telluric acid also needs to be dried in a drying oven at normal pressure, and the drying temperature is preferably 60 ℃~80 ℃.

[0057] To further illustrate the present invention, the following detailed description of a method for preparing telluric acid provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1 A method for selectively preparing telluric acid, the preparation process flow is as follows: Figure 1 As shown, it includes the following steps: (1) Selective leaching of tellurium: Under stirring, 1000 g of crude tellurium slag with a purity greater than 50% and a particle size less than 500 micrometers (crude tellurium slag from smelting crude product) was added to a 5 L quartz beaker containing 1000 mL of sodium hydroxide solution with a concentration of 500 g / L. The alkaline leaching reaction was carried out at a temperature of 30℃. After stirring for 1 h, the product solution was filtered by a ceramic membrane with a filtration accuracy of 0.5 μm to remove insoluble matter, resulting in 158 g of alkaline leaching residue and a transparent sodium tellurite solution. The amount of tellurium leached was 842 g.

[0059] (2) Directional neutralization and precipitation of tellurium: Under stirring, a 25% sulfuric acid solution was slowly added to the sodium tellurite solution obtained above. Specifically, the sulfuric acid solution was added first at an acid addition rate of 8 mL / min to adjust the pH of the system to 8.0, and then the sulfuric acid solution was added at an acid addition rate of 3 mL / min to adjust the pH of the system to 6.5. A neutralization reaction occurred and a large amount of heat was released, generating a white tellurite precipitate. After stirring the reaction for 0.5 h, the solution was filtered off, and the tellurite precipitate was washed with distilled water.

[0060] (3) Mild oxidation conversion: Under heating and stirring, the white tellurite precipitate obtained above was slowly added to a 3 L quartz beaker containing 600 mL of hydrogen peroxide with a mass concentration of 30% for oxidation reaction. The reaction temperature was 100℃ and the oxidation reaction time was 0.5 h. Heating was stopped after the tellurite was completely dissolved in the hydrogen peroxide solution to obtain telluric acid solution.

[0061] (4) Selective precipitation purification of tellurium: After the telluric acid solution is cooled, 1500 mL of 68% concentrated nitric acid is added to a 3 L quartz beaker. Since telluric acid is insoluble in concentrated nitric acid, telluric acid precipitates out of the solution. After stirring the reaction for 0.5 h, the solution is filtered off to obtain the telluric acid precipitate.

[0062] (5) Recrystallization purification: The above-obtained telluric acid precipitate was recrystallized in 1000 mL of distilled water. Specifically, the first crystallization was carried out at 100℃ for 2 hours, and then the second crystallization was carried out at 90℃ for 2 hours. After cooling, the mixture was filtered. The recrystallization mother liquor could be recovered. Specifically, the mother liquor was concentrated and then mixed with the telluric acid precipitate for further recrystallization. After filtration, the telluric acid was dried in an oven at 70℃ to obtain 917 g of telluric acid product. Based on the leached tellurium dioxide mass of 842 g, the telluric acid yield was 75.7%.

[0063] In this embodiment, the XRD pattern of the crude tellurium dioxide slag used is shown in [reference needed]. Figure 2 The results showed that its main component was tellurium dioxide.

[0064] In this embodiment, a physical image of the obtained telluric acid product is shown below. Figure 3 .

[0065] The obtained telluric acid product was characterized by XRD, see [see figure]. Figure 4 .Depend on Figure 4 It can be seen that the obtained telluric acid product has a typical telluric acid phase and no impurity peaks were observed.

[0066] In addition, the present invention performs elemental analysis on the obtained telluric acid product. S and N elements were determined by spectrophotometry, and other elements were determined by inductively coupled plasma atomic emission spectrometry. The results are shown in Table 1. "-" indicates that the element content is below the detection limit. As can be seen from Table 1, the telluric acid content of the telluric acid product obtained in this embodiment is 55.4%, corresponding to a telluric acid purity of 99.6%.

[0067] Table 1. Elemental analysis results of telluric acid products obtained in the embodiments of the present invention.

[0068] In this invention, 100 g of the telluric acid product obtained in the examples was dissolved in 300 mL of distilled water and stirred until fully dissolved to obtain a colorless and transparent solution, with trace amounts remaining insoluble.

[0069] Based on the above experimental results, it can be seen that, compared with the prior art, the present invention has the following significant advantages: (1) Low raw material cost: Using coarse tellurium slag, a by-product of smelting, as raw material, the cost is reduced by more than 40% compared with traditional high-priced raw materials, while realizing the resource utilization of industrial waste residue.

[0070] (2) High product purity: Through three-stage synergistic impurity removal and secondary recrystallization, the product purity reaches more than 99.5%, and the impurity content is controlled below 0.001%, which meets the requirements of high-end fields.

[0071] (3) High tellurium yield: After optimizing the process parameters, the total tellurium yield is stable at over 75.7%, which is 10-15 percentage points higher than the traditional process.

[0072] (4) Green and safe process: Hydrogen peroxide is used as a green oxidant, the reaction conditions are mild and no toxic or harmful gases are generated; nitric acid can be recycled and reused, reagent consumption is reduced by 20% and wastewater discharge is reduced by 30%.

[0073] (5) Simple operation and easy to scale up: The entire process does not require high temperature and high pressure equipment, the operation process is simple, each process is easy to control, and it is suitable for large-scale industrial production.

[0074] Therefore, the high-purity telluric acid prepared by this invention can be widely used in semiconductor material preparation, antiviral drug synthesis, and precision analytical reagents, possessing significant economic value and market prospects. Simultaneously, this method provides a new pathway for the high-value utilization of smelting byproducts, which is of great significance for promoting resource recycling and green chemical development.

[0075] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for selectively preparing telluric acid, characterized in that, Includes the following steps: (1) The tellurium dioxide material is mixed with sodium hydroxide solution for alkaline leaching reaction to obtain sodium tellurite solution; (2) A neutralization reaction was carried out by gradually adding sulfuric acid solution to sodium tellurite solution to obtain tellurite precipitate; (3) The tellurite precipitate was mixed with hydrogen peroxide solution to carry out an oxidation reaction, resulting in a telluric acid solution; (4) Mix the telluric acid solution with concentrated nitric acid, stir, and telluric acid precipitate will be obtained; (5) The telluric acid precipitate was placed in distilled water for recrystallization, filtered, and dried to obtain the telluric acid product.

2. The method according to claim 1, characterized in that, In step (2), the sulfuric acid solution is added in a gradient manner as follows: first, sulfuric acid solution is added at an acid addition rate of 5 mL / min to 10 mL / min to adjust the pH of the system to 7.0 to 8.0; then, sulfuric acid solution is added at an acid addition rate of 2 mL / min to 5 mL / min to adjust the pH of the system to 6.0 to 7.0; the mass concentration of the sulfuric acid solution is 10% to 70%; and the neutralization reaction time is 0.1 h to 0.6 h.

3. The method according to claim 2, characterized in that, In step (2), the mass concentration of the sulfuric acid solution is 20% to 30%; the neutralization reaction time is 0.2 h to 0.5 h; after the neutralization reaction is completed, the following steps are also included: filtering the product of the neutralization reaction, collecting the precipitate, washing the precipitate with distilled water, the washing is performed 2 to 4 times, to obtain tellurite precipitate; the amount of distilled water used is 1 to 2 times that of the precipitate.

4. The method according to claim 3, characterized in that, In step (3), the mass ratio of the hydrogen peroxide solution to the tellurite precipitate is 3.0 to 5.0:1; the mass concentration of the hydrogen peroxide solution is 10% to 50%; the oxidation reaction is carried out at a temperature of 80°C to 110°C; and the oxidation reaction takes 0.1 h to 1 h.

5. The method according to claim 4, characterized in that, In step (3), the mass concentration of the hydrogen peroxide solution is 20% to 40%; the oxidation reaction is carried out at a temperature of 90℃ to 100℃; and the oxidation reaction takes 0.5h to 0.6h.

6. The method according to claim 5, characterized in that, In step (4), the amount of concentrated nitric acid added is 1 to 1.5 times that of the telluric acid solution; the mass concentration of the concentrated nitric acid is 40% to 70%; and the stirring time is 0.2 h to 0.5 h.

7. The method according to claim 6, characterized in that, In step (4), the mass concentration of the concentrated nitric acid is 50% to 70%; the stirring time is 0.3 h to 0.4 h.

8. The method according to any one of claims 1 to 7, characterized in that, In step (1), the ratio of tellurium dioxide material to sodium hydroxide solution is 0.6 g~1.4 g∶1 mL; the tellurium dioxide material is waste residue containing tellurium dioxide; the purity of the tellurium dioxide material is ≥50%; the particle size of the tellurium dioxide material is ≤500 μm; the concentration of the sodium hydroxide solution is 300 g / L~700 g / L; the alkaline leaching reaction is carried out at a temperature of 25℃~35℃; the alkaline leaching reaction time is 0.5 h~1 h; after the alkaline leaching reaction is completed, the product is filtered using a ceramic membrane to remove the filter residue and obtain sodium tellurite solution; the filtration accuracy of the ceramic membrane is 0.1 μm~1.0 μm; In step (5), the recrystallization is carried out as follows: first, a first crystallization is carried out at a temperature of 100℃~110℃ for 1 h~2 h, and then a second crystallization is carried out at a temperature of 90℃~95℃ for 1 h~2 h; the drying is carried out at a temperature of 60℃~80℃ for 2 h~4 h; the mother liquor generated during the recrystallization process is concentrated and then mixed with telluric acid precipitate for further recrystallization.

9. The method according to claim 8, characterized in that, In step (1), the ratio of tellurium dioxide material to sodium hydroxide solution is 0.8 g to 1.3 g: 1 mL; the particle size of tellurium dioxide material is 100 μm to 500 μm; and the concentration of sodium hydroxide solution is 400 g / L to 600 g / L.

10. The method according to claim 9, characterized in that, In step (5), the purity of the telluric acid product is ≥99%.

Images