Process for producing high-purity tellurium

Abstract

The application provides a high-purity tellurium production process, which comprises the following steps: S1, placing crude tellurium in a distillation container for vacuum distillation, collecting the distilled tellurium and crushing the collected tellurium into powder with a fineness of 30-200 meshes; S2, adding the crushed tellurium powder into a reaction kettle, adding hydrogen peroxide and ferrous chloride solution for leaching, ensuring that the hydrogen peroxide is completely consumed, and performing liquid-solid separation on the solution in the reaction kettle to obtain a high-tellurium acid filtrate; S3, cooling the high-tellurium acid filtrate obtained in step S2 to room temperature, then taking supernatant for freeze crystallization, filtering again after the temperature of the supernatant is less than 1 DEG C, and drying and reducing the obtained solid to obtain high-purity tellurium. In the application, the crude tellurium is purified by combining a physical method of vacuum distillation with a chemical method of oxidation and reduction, and various impurity metals in the crude tellurium can be effectively removed through the cooperation of multiple processes, and the removal efficiency is high.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of purification, in particular to a high-purity tellurium production process. BACKGROUND

[0002] High-purity tellurium is an important semiconductor material, has excellent photoelectric performance and thermal stability, and is widely used in the fields of solar cells, infrared detectors, lasers and the like. Since a very small amount of impurities can also cause the electrical performance of the material to deteriorate, the purity of tellurium is an important factor directly affecting the performance of the material.

[0003] The preparation method of high-purity tellurium mainly includes a chemical method and a physical method. The chemical method separates tellurium from impurities through oxidation and reduction chemical reactions, and the method has strong flexibility and great selectivity. The physical method removes impurities through physical processes such as evaporation, solidification, crystallization and diffusion, and mostly adopts multiple vacuum distillation and zone melting to form a physical purification process to prepare high-purity tellurium. For example, patent No. CN202210060094.6 uses zone melting to purify 5N high-purity tellurium into 6N high-purity tellurium; patent No. CN202110660805.9 uses hydrogen to purify 4N refined tellurium into 5N high-purity tellurium, and the adaptability of the raw materials is not wide, and the purity of the products can only be improved by one order of magnitude, and the purification efficiency is not high. SUMMARY

[0004] In view of the above problems, the application provides a high-purity tellurium production process. In the application, a physical method of vacuum distillation and low-temperature crystallization is combined with an oxidation-reduction chemical method to purify crude tellurium. Through the cooperation of multiple processes, various impurity metals in the crude tellurium can be effectively removed, and the removal efficiency is high.

[0005] To solve the above problems, the technical scheme adopted by the application is as follows:

[0006] A high-purity tellurium production process includes the following steps:

[0007] S1, crude tellurium is placed in a distillation container for vacuum distillation, and the distilled tellurium is collected and crushed into powder with a fineness of 30-200 meshes; physical distillation of the crude tellurium can separate tellurium from most high-melting-point impurities, greatly improving the purity of the tellurium; and the tellurium is crushed to a predetermined size, which facilitates grinding and processing, and facilitates subsequent oxidation reaction, improving the efficiency of tellurium purification processing.

[0008] S2, the tellurium powder in a broken powder state is added to a reaction kettle, hydrogen peroxide and ferrous chloride solution are added for leaching, it is ensured that the hydrogen peroxide is completely consumed, and the solution in the reaction kettle is subjected to liquid-solid separation, and high telluric acid filtrate is obtained; compared with the traditional hydrogen peroxide oxidation, the combination of hydrogen peroxide and ferrous chloride can improve the overall oxidation efficiency, and the hydrogen peroxide can be completely consumed, thereby saving resource loss.

[0009] S3, the high telluric acid filtrate obtained in step S2 is cooled to room temperature, and then the supernatant is subjected to freeze crystallization, the supernatant is cooled to a temperature of less than 1 ℃, and then filtered again, and the solid obtained by filtering is dried and reduced to obtain high-purity tellurium; through twice filtering, the purity of high telluric acid in the supernatant can be further ensured, the efficient separation of Se and Te is promoted, and the low-temperature crystallization method can separate the high telluric acid which is insoluble at low temperature from the high selenic acid and other impurities which are easily dissolved at low temperature, thereby effectively purifying tellurium and further ensuring the purity of tellurium.

[0010] Preferably, the distillation container in step S1 is a vertical distillation furnace, the vacuum degree in the distillation process is less than 10 Pa, the distillation temperature is 650-750 ℃, and the distillation time is 3-6 h; the vertical distillation furnace is used for distillation, the distillation operation is simple, the addition and discharge of raw materials are convenient, the overall time of tellurium purification is shortened, and the 2N crude tellurium can be fully distilled and discharged under the above conditions, thereby avoiding the loss of tellurium.

[0011] Preferably, the reaction kettle in step S2 is a double-layer glass reaction kettle, the concentration of hydrogen peroxide is 10-25%, the concentration of ferrous chloride solution is 10-25%, and the amount of hydrogen peroxide added is 0.8-1 times the molar ratio of tellurium; the predetermined proportion of hydrogen peroxide and ferrous chloride can greatly improve the oxidation ability of tellurium, further separate tellurium from other impurities, and meet the needs of oxidation and purification.

[0012] Preferably, the reaction temperature in step S2 is 70-80 ℃, and the reaction time is 3-6 h; under this temperature, the hydrogen peroxide and ferrous chloride can cooperate with each other to the greatest extent to meet the needs of oxidation.

[0013] Preferably, the high telluric acid filtrate in step S2 is subjected to liquid-solid separation by a centrifugal machine, the separated solid is returned to the reaction kettle and reused with newly added tellurium powder by leaching with hydrogen peroxide and ferrous chloride solution, at this time, the tellurium is in an excessive state, the excess unoxidized tellurium powder is discharged and reused, and the overall utilization efficiency can be improved.

[0014] Preferably, the freezing temperature in step S3 is-5-0 ℃, and the freezing time is 3-7 h; the low-temperature freezing method can fully precipitate the high telluric acid in the form of freeze crystallization, and high-purity high telluric acid is obtained.

[0015] Preferably, the separated solid is washed with water twice and then dried in step S3, the drying temperature is 300-320 DEG C, the drying time is 3-5 h, the two times of water washing can remove the impurities in tellurium, and the tellurium is fully dried, so that the subsequent reduction process is facilitated, and the reduction efficiency is improved.

[0016] Preferably, the stainless steel stirring paddle is used for stirring during the drying process, and the rotating speed is 60-120 r / min. The above structure can assist in drying, dispersing the blocky tellurium, accelerating the drying process, and further shortening the overall processing time. At the same time, the above rotating speed can avoid the high tellurium acid solid being lifted, and ensure the cleanliness of the drying environment.

[0017] Preferably, the dried solid is placed in a tube furnace, hydrogen is introduced for reduction, the reaction temperature is 460-490 DEG C, the reaction time is 3-6 h, the hydrogen flow is 2-3 L / min, and high-purity tellurium is collected on the tube wall after the reaction.

[0018] Preferably, in step S2, the solution is treated by ultrasonic vibration during the tellurium oxidation process, and manganese dioxide is added as a catalyst to promote the further oxidation of Se and Te.

[0019] The beneficial effects of the present application are as follows:

[0020] By the present application, high-purity tellurium can be prepared by a short process, and the process route is simple. Meanwhile, the present application can effectively separate various heavy metals in 2N crude tellurium, has good separation effect, and has strong raw material adaptability. The present application is simple, reasonable, economical, practical, and convenient to use. DETAILED DESCRIPTION

[0021] The present application is further described below.

[0022] A production process for preparing high-purity tellurium from crude tellurium, comprising the following steps:

[0023] The 2N crude tellurium is loaded into a vertical distillation furnace for vacuum distillation, the vacuum degree is less than 10 Pa, the distillation temperature is 650-750 DEG C, and the distillation time is 3-6 h.

[0024] The distilled tellurium is collected and broken into powder by using a water-cooled pulverizer, and the pulverization fineness is 30-200 meshes.

[0025] The broken tellurium powder is loaded into a double-layer glass reaction kettle, 10-25 % hydrogen peroxide and 10-25 % ferrous chloride solution are added for leaching, the hydrogen peroxide addition amount is 0.8-1 times of the molar ratio of tellurium, the reaction temperature is 70-80 DEG C, and the reaction time is 3-6 h.

[0026] The reacted solution is subjected to liquid-solid separation by using a centrifuge, and the separated solid is returned to the double-layer glass reaction kettle to be leached with the newly added hydrogen peroxide and ferrous chloride solution.

[0027] After the filtrate is cooled to room temperature, the supernatant is subjected to freeze crystallization, the freezing temperature is -5-0 DEG C, the freezing time is 3-7 h, after the temperature of the supernatant is less than 1 DEG C, the supernatant is filtered again, the separated solid is washed with water for 2 times, and then is dried, the drying temperature is 300-320 DEG C, the drying time is 3-5 h, meanwhile, the 316L stainless steel stirring paddle is used for stirring in the whole process, and the rotating speed is 60-120 r / min.

[0028] The dried solid is placed into a tube furnace, hydrogen is introduced for reduction, the reaction temperature is 460-490 DEG C, the reaction time is 3-6 h, the hydrogen flow is 2-3 L / min, and high-purity tellurium is collected on the tube wall after the reaction.

[0029] Further, the inside of the vertical distillation furnace is tray type, the material loading crucible is made of high-purity graphite, and the tray is made of high-purity graphite or high-purity quartz.

[0030] Further, the amount of the ferrous chloride solution is 0.7-1 times of the amount of the hydrogen peroxide, and H2O2 is decomposed to generate ·OH under the catalysis of Fe 2+ , so that the rapid oxidation of Se and Te into high-valence ion state is promoted, and the subsequent separation of Se and Te is facilitated.

[0031] Further, when the hydrogen peroxide and the ferrous chloride are used for leaching, 0.01-0.3% of manganese dioxide of the total amount of tellurium is added to the solution to enhance the oxidation effect, and the manganese dioxide promotes the decomposition of the hydrogen peroxide to generate oxygen.

[0032] Further, when the hydrogen peroxide and the ferrous chloride are used for leaching, an ultrasonic vibration rod is used for ultrasonic treatment of the solution. In the ultrasonic system, the ultrasonic wave provides a large amount of heat for the generation of active free radicals, and the mass transfer rate of the aqueous solution is increased through turbulent flow. When O2 exists in the reaction system, the ·OH generated by the cracking of O2 can initiate the further reaction of H2O and H2O2 to generate ·OH, and further promote the further oxidation of Se and Te.

[0033] Further, the furnace tube in the tube furnace is made of high-purity quartz.

[0034] Further, the hydrogen is prepared by using a hydrogen generator, and the purity is 99.999%.

[0035] The beneficial effects of the present application are as follows:

[0036] The present application can realize short process preparation of high-purity tellurium, and the process route is simple, and the present application can effectively separate various heavy metals in 2N crude tellurium, has good separation effect, and has strong raw material adaptability.

[0037] The application is further described below in conjunction with specific embodiments

[0038] Example 1

[0039] 2N crude tellurium is put into a vertical distillation furnace for vacuum distillation, the vacuum degree is 5 Pa, the distillation temperature is 680 DEG C, and the distillation time is 4 h. After the distillation is completed, the collected tellurium is crushed into powder by using a water-cooled pulverizer, and the crushing fineness is 30-200 meshes. The crushed tellurium powder is loaded into a double-layer glass reaction kettle, 15% hydrogen peroxide and a ferric chloride solution are added for leaching, the hydrogen peroxide is added in a molar ratio of 0.8 times that of the tellurium, the ferric chloride solution is added in a ratio of 0.8 times that of the hydrogen peroxide, 0.05% manganese dioxide of the total amount of tellurium is further added, the reaction temperature is 75 DEG C, the reaction time is 3 h, and ultrasonic treatment is simultaneously increased. The solution after the reaction is subjected to liquid-solid separation by using a centrifuge, the filtrate is cooled to room temperature after standing, and then the supernatant is subjected to freeze crystallization, the freezing temperature is -1 DEG C, the freezing time is 4 h, after the temperature of the supernatant is <1 DEG C, the solid is filtered again, the separated solid is washed with water twice and dried, the drying temperature is 310 DEG C, the drying time is 4 h, a 316L stainless steel stirring paddle is used for stirring throughout the process, and the rotating speed is 80 r / min. The dried solid is put into a tube furnace, hydrogen is introduced for reduction, the reaction temperature is 470 DEG C, the reaction time is 4 h, the hydrogen flow rate is 2.2 L / min, after the reaction is completed, high-purity tellurium is collected on the tube wall, and the test results are shown in Table 1.

[0040] Example 2

[0041] The 2N crude tellurium was put into a vertical distillation furnace for vacuum distillation, vacuum degree 5 Pa, distillation temperature 690°C, distillation time 4 h. After the distillation was completed, the collected tellurium was broken into powder by using a water-cooled pulverizer, and the pulverization fineness was 30-200 mesh. The broken tellurium powder was loaded into a double-layer glass reaction kettle, 17% hydrogen peroxide and ferric chloride solution were added for leaching, the hydrogen peroxide was added in a molar ratio of 0.82 times that of tellurium, the ferric chloride solution was added in a ratio of 0.85 times that of the hydrogen peroxide, 0.09% manganese dioxide was further added, the reaction temperature was 75°C, the reaction time was 3 h, and ultrasonic treatment was simultaneously increased. The solution after the reaction was subjected to liquid-solid separation by using a centrifuge, the filtrate was cooled to room temperature after standing, and then the supernatant was taken for freeze crystallization, the freezing temperature was -2°C, the freezing time was 4 h, and after the temperature of the supernatant was <1°C, the solid was separated again, washed with water twice, and dried, the drying temperature was 310°C, the drying time was 4 h, and a 316L stainless steel stirring paddle was used for stirring throughout the process, and the rotating speed was 90 r / min. The dried solid was put into a tube furnace, hydrogen was introduced for reduction, the reaction temperature was 480°C, the reaction time was 3.5 h, the hydrogen flow rate was 2.4 L / min, and after the reaction was completed, high-purity tellurium was collected on the tube wall, and the test results are shown in Table 1.

[0042] Example 3

[0043] The 2N crude tellurium was put into a vertical distillation furnace for vacuum distillation, vacuum degree 5 Pa, distillation temperature 680°C, distillation time 4 h. After the distillation was completed, the collected tellurium was broken into powder by using a water-cooled pulverizer, and the pulverization fineness was 30-200 mesh. The broken tellurium powder was loaded into a double-layer glass reaction kettle, 19% hydrogen peroxide and ferric chloride solution were added for leaching, the hydrogen peroxide was added in a molar ratio of 0.86 times that of tellurium, the ferric chloride solution was added in a ratio of 0.93 times that of the hydrogen peroxide, 0.07% manganese dioxide was further added, the reaction temperature was 75°C, the reaction time was 3 h, and ultrasonic treatment was simultaneously increased. The solution after the reaction was subjected to liquid-solid separation by using a centrifuge, the filtrate was cooled to room temperature after standing, and then the supernatant was taken for freeze crystallization, the freezing temperature was -1°C, the freezing time was 5 h, and after the temperature of the supernatant was <1°C, the solid was separated again, washed with water twice, and dried, the drying temperature was 315°C, the drying time was 4 h, and a 316L stainless steel stirring paddle was used for stirring throughout the process, and the rotating speed was 70 r / min. The dried solid was put into a tube furnace, hydrogen was introduced for reduction, the reaction temperature was 490°C, the reaction time was 4 h, the hydrogen flow rate was 2.3 L / min, and after the reaction was completed, high-purity tellurium was collected on the tube wall, and the test results are shown in Table 1.

[0044] Table 1 Component analysis / ppm

[0045]

[0046] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the production of high purity tellurium, characterized in that, It comprises the following steps: S1, the crude tellurium is placed in a distillation vessel for vacuum distillation, and the distilled tellurium is collected and crushed into powder with a fineness of 30-200 mesh; S2, the crushed tellurium powder is added to a reaction kettle, hydrogen peroxide and ferrous chloride solution are added for leaching, the hydrogen peroxide is completely consumed, and the solution in the reaction kettle is subjected to liquid-solid separation to obtain a high tellurium acid filtrate; In the process of step S2, the solution is treated by ultrasonic vibration rod, and manganese dioxide is added as a catalyst to promote the further oxidation of Se and Te; S3, the high tellurium acid filtrate obtained in step S2 is cooled to room temperature, and the supernatant is then frozen and crystallized, and after the temperature of the supernatant is <1℃, the filtrate is filtered, and the obtained solid is dried and reduced to obtain high-purity tellurium.

2. The process for producing high purity tellurium according to claim 1, wherein, The distillation vessel in step S1 is a vertical distillation furnace, the vacuum degree during distillation is less than 10 Pa, the distillation temperature is 650-750℃, and the distillation time is 3-6h.

3. The process for producing high purity tellurium according to claim 1, wherein The reaction kettle in step S2 is a double-layer glass reaction kettle, the concentration of hydrogen peroxide is 10-25%, the concentration of ferrous chloride solution is 10-25%, and the amount of hydrogen peroxide added is 0.8-1 times the molar ratio of tellurium.

4. The process for producing high purity tellurium according to claim 1, wherein The reaction temperature in step S2 is 70-80℃, and the reaction time is 3-6h.

5. The process for producing high purity tellurium according to claim 1, wherein The tellurium filtrate in step S2 is subjected to liquid-solid separation by a centrifuge, and the separated solid is returned to the reaction kettle for re-leaching with hydrogen peroxide and ferrous chloride solution.

6. The process for producing high purity tellurium according to claim 1, wherein The freezing temperature in step S3 is -5-0℃, and the freezing time is 3-7h.

7. The process for producing high purity tellurium according to claim 1, wherein The separated solid in step S3 is washed with water for 2 times and then dried, the drying temperature is 300-320℃, and the drying time is 3-5h.

8. The process for producing high purity tellurium according to claim 7, wherein During the drying process, stainless steel stirring paddles are used for full-time stirring at a speed of 60-120r / min.

9. The process for producing high purity tellurium according to claim 1, wherein The dried solid is placed in a tube furnace, hydrogen is introduced for reduction, the reaction temperature is 460-490℃, the reaction time is 3-6h, the hydrogen flow rate is 2-3L / min, and high-purity tellurium is collected on the tube wall after the reaction is completed.

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