A production device and production method for preparing 6N high-purity tellurium by horizontal vacuum distillation

Abstract

A production device and method for preparing 6N high-purity tellurium by horizontal vacuum distillation. The production device includes a horizontal tube; a first heater, a second heater, and a heat-insulating cover are provided outside the horizontal tube, corresponding to a first heating zone, a second heating zone, and a heat-insulating zone, respectively; a graphite sleeve, a first-stage condenser, and a second-stage condenser are provided in sequence inside the horizontal tube; a graphite boat is located in the first heating zone; and a tellurium material is loaded in the graphite boat. The present invention also includes a production method. The present invention achieves efficient separation of metallic tellurium from low-boiling impurities and high-boiling impurity elements, thereby achieving the preparation of 6N high-purity tellurium; the use of horizontal vacuum distillation to prepare high-purity tellurium has a driving force that is less affected by gravity, weakening the influence of the gravitational field, resulting in a short process and high impurity removal efficiency; the test process is convenient for loading and removing samples, and the operation is easy.

Description

Technical Field

[0001] The present invention relates to a production device and a production method for preparing high-purity tellurium by vacuum distillation, and in particular to a production device and a production method for preparing high-purity tellurium by horizontal vacuum distillation. Background Art

[0002] Tellurium is a typical rare earth metal, found in the Earth's crust at a concentration of only 0.001 to 0.005 g / t. Despite its limited reserves, it has a wide range of applications in infrared detection, solar technology, semiconductors, 5G communications, and military applications. For example, CdTe is a key solar cell material, Bi2Te3 and PbTe are excellent refrigeration materials, and HgCdTe, ZnCdTe, and PbSnTe are primarily used in infrared detection and military applications. Trace impurities in tellurium can directly affect material properties. For example, in infrared detection and guidance for military weapons, the presence of impurities can reduce detection accuracy, thereby shortening the combat radius and accuracy of advanced weapons. Therefore, high-purity tellurium is crucial.

[0003] Tellurium purification techniques include chemical and physical methods. Chemical purification methods include extraction, precipitation, and electrolysis, while physical purification methods include vacuum distillation, zone melting, and Czochralski purification. Chemical methods generally only purify tellurium to 4N. Tellurium is a metal with a low melting point and high saturated vapor pressure. Vacuum distillation can effectively remove most impurities from tellurium, yielding high-purity distilled tellurium. Tellurium has a melting point of approximately 452°C and a boiling point of approximately 1390°C. It begins to volatilize at 400°C under vacuum conditions. The saturated vapor pressures of tellurium impurities at various temperatures are shown in Table 1 below.

[0004] Table 1 Saturated vapor pressure of tellurium and impurities at various temperatures

[0005]

[0006] When the temperature reaches 500°C, the saturated vapor pressure difference between tellurium and impurities is large. At this time, metallic tellurium and impurities are easier to separate during the vacuum distillation process. Therefore, the actual experimental and production processes are generally controlled at around 500°C. However, as can be seen from the above table, at around 500°C, the saturated vapor pressure of impurities such as Se, S, As, and Mg is relatively close to that of tellurium, making them difficult to remove through conventional vacuum distillation. Existing vertical vacuum distillation technology mostly uses 2N-4N metals as raw materials, and 5N high-purity tellurium is prepared through multiple distillations. It is difficult to further purify 5N tellurium to 6N, and the preparation process is long, production efficiency is low, and impurity removal rate is low.

[0007] Traditional vacuum distillation technology mostly uses vertical vacuum furnaces. During the distillation process, the migration of impurities in tellurium is affected by gravity, thereby reducing the separation efficiency of impurities and main metals. In addition, the sampling and sampling processes in the test and production processes are relatively cumbersome and inconvenient to operate.

[0008] CN101892496A discloses a method for producing 5N high-purity tellurium using 3N crude tellurium as a raw material. This method first uses 3N crude tellurium to prepare a crude tellurium anode. Then, tellurium dioxide is used to prepare an electrolyte. Electrolytic refining is performed in an alkaline electrolytic cell using a titanium plate as a cathode for 3-5 days to produce 5N tellurium. The electrolytic process for producing high-purity tellurium is long, complex, consumes a lot of reagents, has a high risk of contamination during the operation, and has low current efficiency.

[0009] CN107313063A discloses a method for smelting 5N high-purity tellurium. This method combines electrolytic refining and vacuum distillation. First, 4N tellurium is prepared by low-current density electrowinning. Then, the 4N tellurium ingot is subjected to low-temperature vacuum distillation to produce distilled tellurium. Finally, the distilled tellurium is crushed into small particles, and the ingot is heated under the action of hydrogen flow to obtain 5N high-purity tellurium. The process is long and the operation is cumbersome.

[0010] CN107585745A discloses a 5N tellurium production process, which significantly reduces the content of some impurities in the raw materials through pretreatment, thereby significantly reducing the content of impurities in the raw materials that are difficult to separate. Vacuum distillation, hydrogenation and selenium reduction, and medium-frequency ingot casting are then performed to obtain 5N high-purity tellurium. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a horizontal vacuum distillation production device and a production method capable of preparing 6N high-purity tellurium.

[0012] The technical solution adopted by the present invention to solve the technical problem is as follows: a production device for preparing 6N high-purity tellurium by horizontal vacuum distillation, comprising a horizontal tube; one end of the horizontal tube is closed and the other end is sealed by a sealing valve, and one end of the sealing valve is provided with an air outlet; the horizontal tube is connected to a vacuum pumping system through the air outlet;

[0013] Outside the horizontal pipe, from the closed end to the sealing valve end, there are sequentially provided a first heater, a second heater, and a heat preservation cover, corresponding to the first heating zone, the second heating zone, and the heat preservation zone respectively;

[0014] Inside the horizontal tube, from the closed end to the sealed valve end, there are a graphite sleeve, a primary condenser, and a secondary condenser in sequence; the graphite sleeve is located in the first heating zone, the secondary condenser is located in the insulation zone, and the primary condenser extends from the first heating zone to the insulation zone;

[0015] The graphite boat is located in the first heating zone; the tellurium material is loaded in the graphite boat.

[0016] By adopting the above technical solution, multiple sections of independent temperature control and segmented condensation can be achieved to realize the efficient separation of metallic tellurium from low-boiling impurities and high-boiling impurity elements.

[0017] Preferably, there is a gap of less than 20 mm between the first heater and the second heater, corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser extends from the first heating zone to the insulation zone, or from the transition zone to the insulation zone.

[0018] The present invention is provided with two heaters, wherein a graphite boat is placed in a first heating zone corresponding to the first heater, and the first heater mainly plays the role of controlling the temperature of the distillation zone; a first condenser is placed in a second heating zone corresponding to the second heater, and the second heater mainly plays the role of controlling the condensation effect of the first condenser.

[0019] Insulation materials may also be provided around the first heater 1 - 1 and the second heater 1 - 2 , as well as the corresponding first heating zone and the second heating zone, in a conventional manner, which is beneficial to energy saving.

[0020] Preferably, the horizontal tube is further provided with an air inlet, through which the horizontal tube is connected to an air inlet system providing an inert atmosphere; an air inlet valve is provided between the air inlet and the air inlet system, and an air outlet valve is provided between the air outlet and the vacuum system.

[0021] The adoption of the above technical solution helps to remove air and prevent air from contaminating the sample.

[0022] Preferably, there is a gap of 5 to 10 mm between the first heater and the second heater; the graphite sleeve is 50 to 100 mm longer than the graphite boat; and the first-level condenser is 700 to 800 mm long.

[0023] By adopting the above technical solution, a better distillation effect is achieved.

[0024] Preferably, the secondary condenser is 700-800 mm long; and the graphite boat is 500-600 mm long.

[0025] By adopting the above technical solution, a better distillation effect is achieved.

[0026] The tellurium product is condensed in the primary condenser, and the secondary condenser mainly serves to collect low-boiling products.

[0027] Preferably, the vacuum system is connected to an exhaust gas treatment system. The exhaust gas treatment system is primarily used to treat exhaust gas containing tellurium and impurities. Filter cotton can be installed in the exhaust gas treatment system to remove volatilized selenium, tellurium, and other gas particles.

[0028] Preferably, the impurity content of the graphite boat and the graphite sleeve is below 5 ppm.

[0029] Adopting the above technical solution helps to obtain high-purity tellurium.

[0030] Preferably, the inert gas provided by the air intake system has a purity of 6N or above.

[0031] Adopting the above technical solution helps to obtain high-purity tellurium.

[0032] The present invention provides a method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation, characterized in that:

[0033] Before starting vacuum distillation, control the vacuum degree in the horizontal tube to 10 -2 Below Pa;

[0034] Two-stage distillation is adopted: the temperature of the first heater in the first distillation is 400-450°C, and the temperature of the second heater is 350-400°C; the time of the first distillation is 1-2 hours; the temperature of the first heater in the second distillation is 480-530°C, and the temperature of the second heater is 300-350°C; the time of the second distillation is 2-4 hours.

[0035] Because tellurium impurities such as Se, S, and As are highly volatile and have a saturated vapor pressure close to that of metallic tellurium, effective condensation during distillation is difficult. Therefore, a lower-temperature distillation stage is initially set up to initially volatilize the Se, S, and As impurities. The gaseous tellurium, which contains a higher concentration of these impurities, passes through the primary condenser and condenses in the secondary condenser, achieving a preliminary separation of the tellurium metal from the impurities in the high-purity graphite boat. In the second stage of distillation, the temperature of the first heater is raised to 480-530°C, while the temperature of the second heater remains unchanged or appropriately lowered, allowing the tellurium metal to fully volatilize and condense in the primary condenser. Ultimately, high-purity tellurium is fully condensed in the primary condenser, low-boiling substances are condensed in the secondary condenser, and high-boiling substances remain in the high-purity graphite boat, effectively separating tellurium from impurity elements.

[0036] Preferably, the steps include:

[0037] (S1) Charging: Weigh the tellurium material, put it into the graphite boat, and place the graphite boat into the graphite sleeve; close the sealing valve;

[0038] (S2) Vacuuming: Introduce inert gas into the horizontal tube through the air intake system to replace the air in the horizontal tube; close the air intake valve, open the air outlet valve, and control the vacuum degree in the horizontal tube to 10 -2 Below Pa;

[0039] (S3) distillation: performing the two-stage distillation;

[0040] (S4) Sampling; After the distillation is completed, the heating power is turned off, and after the temperature drops to room temperature, the crystallized tellurium located in the primary condenser is obtained.

[0041] By adopting the above technical solution, a better distillation effect is achieved.

[0042] More preferably, in step (S2), process (a) and process (b) are alternately performed to replace the air in the horizontal tube with an inert gas:

[0043] (a) Close the outlet valve and vacuum system, and open the inlet valve and air intake system;

[0044] (b) Close the air inlet valve and the air inlet system, and open the air outlet valve and the vacuum system.

[0045] By adopting the above technical solution, a better air removal effect is achieved, which can prevent air from contaminating the sample.

[0046] More preferably, in step (S4), after turning off the heating power supply, wait until the temperature drops below 200°C, turn off the vacuum system, open the air intake system and the air intake valve to form an inert atmosphere with a slightly positive pressure in the horizontal tube.

[0047] The above technical solution is helpful to obtain high-purity tellurium and can prevent air from entering to avoid contamination of the sample.

[0048] Traditional vertical vacuum distillation can generally only purify tellurium metal to 5N, and it also involves a long process, low recovery rates, and inconsistent product quality. The horizontal vacuum distillation apparatus of the present invention connects one side to a vacuum pump, providing a driving force for the migration of tellurium and impurities. The gravity field is directed vertically downward, so the driving force is not offset by gravity. Compared to vertical distillation, this weakens the influence of the gravity field, increases the metal vapor migration rate, strengthens the mass transfer process during distillation, and improves the separation efficiency of impurities and the main metal, capable of purifying tellurium metal to 6N. Furthermore, the sample loading and removal process is convenient.

[0049] The present invention adopts two heaters and two-stage condenser tubes to realize multi-stage independent temperature control and segmented condensation, and can separate impurities such as Se, S, As, Mg, etc. whose saturated vapor pressure is close to that of tellurium, and realize the preparation of 6N high-purity tellurium.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) Achieve efficient separation of tellurium metal from low-boiling impurities and high-boiling impurity elements, and achieve the preparation of 6N high-purity tellurium;

[0052] (2) The horizontal vacuum distillation method is used to prepare high-purity tellurium. The driving force is less affected by gravity, which weakens the influence of the gravity field, shortens the process, and has high impurity removal efficiency.

[0053] (3) The test process is convenient for loading and sampling and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a schematic diagram of the structure of the production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation in Example 1.

[0055] Description of reference numerals:

[0056] 1-1: First heater; 1-2: Second heater; 2: Tellurium material; 3: Graphite boat; 4: Graphite sleeve; 5: Horizontal tube; 6: Primary condenser; 7: Secondary condenser; 8-2: Inlet valve; 8-3: Outlet valve; 9: Inlet system; 10: Sealing valve; 12: Inlet port; 13: Outlet port; 16: Vacuuming system; 17: Exhaust gas treatment system; 18: Furnace body; 19: Insulation cover. DETAILED DESCRIPTION

[0057] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0058] The raw materials used in the examples of the present invention were all obtained through conventional commercial channels.

[0059] The following are merely preferred embodiments, and the invention can be implemented in many different ways as defined and covered by the claims.

[0060] Example 1

[0061] refer to Figure 1 The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes a horizontal tube 5; one end of the horizontal tube 5 is closed, and the other end is sealed by a sealing valve 10, and one end of the sealing valve 10 is provided with an air outlet 13; the horizontal tube 5 is connected to a vacuum system 16 through the air outlet 13;

[0062] Outside the horizontal pipe 5, from the closed end to the sealing valve 10 end, there are sequentially provided a first heater 1-1, a second heater 1-2, and a heat preservation cover 19, which correspond to the first heating zone, the second heating zone, and the heat preservation zone respectively;

[0063] Inside the horizontal tube 5, from the closed end to the sealing valve 10 end, there are sequentially provided a graphite sleeve 4, a primary condenser 6, and a secondary condenser 7; the graphite sleeve 4 is located in the first heating zone, and the secondary condenser 7 is located in the insulation zone;

[0064] In this embodiment, the first heater 1-1 and the second heater 1-2 are located in the same furnace body 18, and the two heaters are 10 mm apart, corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser 6 extends from the transition zone to the insulation zone.

[0065] The graphite boat 3 is located in the first heating zone, and the tellurium material 2 is loaded in the graphite boat 3. The graphite boat 3 is 500 mm long, the graphite sleeve 4 is 550 mm long, the first-stage condenser 6 is 700 mm long, and the second-stage condenser 7 is 700 mm long.

[0066] The horizontal tube 5 is also provided with an air inlet 12, through which the horizontal tube 5 is connected to an air inlet system 9 providing an inert atmosphere; an air inlet valve 8-2 is provided between the air inlet 12 and the air inlet system 9, and an air outlet valve 8-3 is provided between the air outlet 13 and the vacuum system 16.

[0067] The vacuum system 16 is connected to an exhaust gas treatment system 17. The exhaust gas treatment system 17 is equipped with filter cotton to remove volatilized gas particles such as selenium and tellurium.

[0068] The impurity content of the graphite boat 3 and the graphite sleeve 4 is below 5 ppm.

[0069] The inert gas provided by the air intake system 9 has a purity of 6N or above.

[0070] The horizontal tube 5 in this embodiment is made of stainless steel.

[0071] The method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes the following steps:

[0072] (S1) Charging: Weigh 3.5 kg of 5N tellurium material and place it into the graphite boat 3, which is then placed into the graphite sleeve 4; close the sealing valve 10;

[0073] (S2) Vacuuming: Inert gas is introduced into the horizontal tube 5 through the air intake system 9 to replace the air in the horizontal tube 5; the air intake valve 8-2 is closed, the air outlet valve 8-3 is opened, and the vacuum degree in the horizontal tube 5 is controlled to 10 by the vacuuming system 16. -2 Below Pa;

[0074] (S3) Distillation: A two-stage distillation is performed: the temperature of the first heater during the first stage of distillation is 400° C., and the temperature of the second heater is 350° C.; the time for the first stage of distillation is 1.5 hours; the temperature of the first heater during the second stage of distillation is 480° C., and the temperature of the second heater is 300° C.; the time for the second stage of distillation is 3.5 hours; after distillation, the tellurium in the graphite boat 3 is fully volatilized, the tellurium is fully condensed in the first condenser 6, the low-boiling substances are condensed in the second condenser 7, and the high-boiling substances remain in the graphite boat 3, thereby achieving effective separation of tellurium and impurity elements;

[0075] (S4) Sampling; after the distillation is completed, turn off the heating power supply; when the temperature drops below 200°C, turn off the vacuum system, open the air intake system 9 and the air intake valve 8-2 to form an inert atmosphere with a slightly positive pressure in the horizontal tube 5; after the temperature drops to room temperature, close the air intake system 9, the air intake valve 8-2 and the air outlet valve 8-3, open the sealing valve 10, and take out the secondary condenser 7, the primary condenser 6, and the graphite sleeve 4 in turn; the crystallized tellurium is located in the primary condenser 6, and high-purity tellurium is obtained.

[0076] In step (S2), process (a) and process (b) are alternately performed three times to replace the air in the horizontal tube 5 with the inert gas; that is, (a)-(b)-(a)-(b)-(a)-(b) are performed in sequence; wherein:

[0077] (a) Close the outlet valve 8-3 and the vacuum system 16, open the inlet valve 8-2 and the inlet system 9, and ventilate for 10 minutes;

[0078] (b) Close the air inlet valve 8-2 and the air inlet system 9, open the air outlet valve 8-3 and the vacuum system 16, and evacuate the air until the pressure in the horizontal pipe 5 is below 100 Pa.

[0079] The GDMS analysis results of the tellurium product obtained in this example are shown in Table 2. It can be seen that the impurity content of the tellurium product obtained in this example is significantly reduced compared to the raw material, reaching the 6N level. The units in Table 2 are ppbw.

[0080] Table 2 Statistics of impurity content of high-purity tellurium obtained in Example 1 (unit: ppbw)

[0081] element Mg Al Ca Fe Ni Cu Zn Se Ag Cd Pb As S Tellurium raw materials 68 72 65 102 40 91 40 163 31 32 35 46 38 standard <50 <50 <100 <50 <50 <10 <100 <100 <10 <50 <50 / / Example 1 8 <5 12 <0.5 <0.5 <1 7.1 58 <1 <5 <5 3.3 4

[0082] Example 2

[0083] The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes a horizontal tube 5 ; one end of the horizontal tube 5 is closed, and the other end is sealed by a sealing valve 10 ; an air outlet 13 is provided at one end of the sealing valve 10 ; the horizontal tube 5 is connected to a vacuum pumping system 16 via the air outlet 13 ;

[0084] Outside the horizontal pipe 5, from the closed end to the sealing valve 10 end, there are sequentially provided a first heater 1-1, a second heater 1-2, and a heat preservation cover 19, which correspond to the first heating zone, the second heating zone, and the heat preservation zone respectively;

[0085] Inside the horizontal tube 5, from the closed end to the sealing valve 10 end, there are sequentially provided a graphite sleeve 4, a primary condenser 6, and a secondary condenser 7; the graphite sleeve 4 is located in the first heating zone, and the secondary condenser 7 is located in the insulation zone;

[0086] In this embodiment, the first heater 1-1 and the second heater 1-2 are spaced 5 mm apart, corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser 6 extends from the transition zone to the insulation zone.

[0087] The graphite boat 3 is located in the first heating zone, and the tellurium material 2 is loaded in the graphite boat 3. The graphite boat 3 is 600 mm long, the graphite sleeve 4 is 700 mm long, the first-level condenser 6 is 800 mm long, and the second-level condenser 7 is 800 mm long.

[0088] The horizontal tube 5 is also provided with an air inlet 12, through which the horizontal tube 5 is connected to an air inlet system 9 providing an inert atmosphere; an air inlet valve 8-2 is provided between the air inlet 12 and the air inlet system 9, and an air outlet valve 8-3 is provided between the air outlet 13 and the vacuum system 16.

[0089] The vacuum pumping system 16 is connected to the tail gas treatment system 17 .

[0090] The impurity content of the graphite boat 3 and the graphite sleeve 4 is below 5 ppm.

[0091] The inert gas provided by the air intake system 9 has a purity of 6N or above.

[0092] The horizontal tube 5 in this embodiment is a quartz tube.

[0093] The method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes the following steps:

[0094] (S1) Charging: Weigh 3.8 kg of 5N tellurium material and place it into the graphite boat 3, which is then placed into the graphite sleeve 4; close the sealing valve 10;

[0095] (S2) Vacuuming: Inert gas is introduced into the horizontal tube 5 through the air intake system 9 to replace the air in the horizontal tube 5; the air intake valve 8-2 is closed, the air outlet valve 8-3 is opened, and the vacuum degree in the horizontal tube 5 is controlled to 10 by the vacuuming system 16. -2 Below Pa;

[0096] (S3) Distillation: A two-stage distillation is performed: the temperature of the first heater during the first distillation is 400° C., and the temperature of the second heater is 400° C.; the time for the first distillation is 1.5 hours; the temperature of the first heater during the second distillation is 500° C., and the temperature of the second heater is 300° C.; the time for the second distillation is 2.5 hours; after distillation, the tellurium in the graphite boat 3 is fully volatilized, the tellurium is fully condensed in the first condenser 6, the low-boiling substances are condensed in the second condenser 7, and the high-boiling substances remain in the graphite boat 3, thereby achieving effective separation of tellurium and impurity elements;

[0097] (S4) Sampling; after the distillation is completed, turn off the heating power supply; when the temperature drops below 200°C, turn off the vacuum system, open the air intake system 9 and the air intake valve 8-2 to form an inert atmosphere with a slightly positive pressure in the horizontal tube 5; after the temperature drops to room temperature, close the air intake system 9, the air intake valve 8-2 and the air outlet valve 8-3, open the sealing valve 10, and take out the secondary condenser 7, the primary condenser 6, and the graphite sleeve 4 in turn; the crystallized tellurium is located in the primary condenser 6, and high-purity tellurium is obtained.

[0098] In step (S2), process (a) and process (b) are alternately performed three times to replace the air in the horizontal tube 5 with the inert gas; that is, (a)-(b)-(a)-(b)-(a)-(b) are performed in sequence; wherein:

[0099] (a) Close the outlet valve 8-3 and the vacuum system 16, open the inlet valve 8-2 and the inlet system 9, and ventilate for 8 minutes;

[0100] (b) Close the air inlet valve 8-2 and the air inlet system 9, open the air outlet valve 8-3 and the vacuum system 16, and evacuate the air until the pressure in the horizontal pipe 5 is below 100 Pa.

[0101] The GDMS analysis results of the tellurium product obtained in this example are shown in Table 3. It can be seen that the impurity content of the tellurium product obtained in this example is significantly reduced compared to the raw material, reaching the 6N level. The units in Table 3 are ppbw.

[0102] Table 3 Statistics of impurity content of high-purity tellurium obtained in Example 2 (unit: ppbw)

[0103] element Mg Al Ca Fe Ni Cu Zn Se Ag Cd Pb As S Tellurium raw materials 51 82 61 113 36 131 28 283 31 20 55 54 43 standard <50 <50 <100 <50 <50 <10 <100 <100 <10 <50 <50 / / Example 2 2 <5 10 <0.5 <0.5 <1 1.1 79 <1 <5 <5 5 4.6

[0104] Example 3

[0105] The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes a horizontal tube 5 ; one end of the horizontal tube 5 is closed, and the other end is sealed by a sealing valve 10 ; an air outlet 13 is provided at one end of the sealing valve 10 ; the horizontal tube 5 is connected to a vacuum pumping system 16 via the air outlet 13 ;

[0106] Outside the horizontal pipe 5, from the closed end to the sealing valve 10 end, there are sequentially provided a first heater 1-1, a second heater 1-2, and a heat preservation cover 19, which correspond to the first heating zone, the second heating zone, and the heat preservation zone respectively;

[0107] Inside the horizontal tube 5, from the closed end to the sealing valve 10 end, there are sequentially provided a graphite sleeve 4, a primary condenser 6, and a secondary condenser 7; the graphite sleeve 4 is located in the first heating zone, and the secondary condenser 7 is located in the insulation zone;

[0108] In this embodiment, the first heater 1-1 and the second heater 1-2 are spaced 15 mm apart, corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser 6 extends from the transition zone to the insulation zone.

[0109] The graphite boat 3 is located in the first heating zone, and the tellurium material 2 is placed in the graphite boat 3. The graphite boat 3 is 600 mm long, the graphite sleeve 4 is 700 mm long, the first-stage condenser 6 is 700 mm long, and the second-stage condenser 7 is 700 mm long.

[0110] The horizontal tube 5 is also provided with an air inlet 12, through which the horizontal tube 5 is connected to an air inlet system 9 providing an inert atmosphere; an air inlet valve 8-2 is provided between the air inlet 12 and the air inlet system 9, and an air outlet valve 8-3 is provided between the air outlet 13 and the vacuum system 16.

[0111] The vacuum pumping system 16 is connected to the tail gas treatment system 17 .

[0112] The impurity content of the graphite boat 3 and the graphite sleeve 4 is below 5 ppm.

[0113] The inert gas provided by the air intake system 9 has a purity of 6N or above.

[0114] The horizontal tube 5 in this embodiment is a quartz tube.

[0115] The method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes the following steps:

[0116] (S1) Charging: Weigh 4.2 kg of 5N tellurium material and place it into the graphite boat 3, which is then placed into the graphite sleeve 4; close the sealing valve 10;

[0117] (S2) Vacuuming: Inert gas is introduced into the horizontal tube 5 through the air intake system 9 to replace the air in the horizontal tube 5; the air intake valve 8-2 is closed, the air outlet valve 8-3 is opened, and the vacuum degree in the horizontal tube 5 is controlled to 10 by the vacuuming system 16. -2 Below Pa;

[0118] (S3) Distillation: A two-stage distillation is performed: during the first stage of distillation, the temperature of the first heater is 450° C., and the temperature of the second heater is 350° C.; the time of the first stage of distillation is 1.2 hours; during the second stage of distillation, the temperature of the first heater is 530° C., and the temperature of the second heater is 300° C.; the time of the second stage of distillation is 3 hours. After distillation, the tellurium in the graphite boat 3 is fully volatilized and fully condensed in the first condenser 6, the low-boiling substances are condensed in the second condenser 7, and the high-boiling substances remain in the graphite boat 3, thereby achieving effective separation of tellurium and impurity elements;

[0119] (S4) Sampling; after the distillation is completed, turn off the heating power supply; when the temperature drops below 200°C, turn off the vacuum system, open the air intake system 9 and the air intake valve 8-2 to form an inert atmosphere with a slightly positive pressure in the horizontal tube 5; after the temperature drops to room temperature, close the air intake system 9, the air intake valve 8-2 and the air outlet valve 8-3, open the sealing valve 10, and take out the secondary condenser 7, the primary condenser 6, and the graphite sleeve 4 in turn; the crystallized tellurium is located in the primary condenser 6, and high-purity tellurium is obtained.

[0120] In step (S2), process (a) and process (b) are alternately performed twice to replace the air in the horizontal tube 5 with the inert gas; that is, (a)-(b)-(a)-(b) are performed in sequence; wherein:

[0121] (a) Close the outlet valve 8-3 and the vacuum system 16, open the inlet valve 8-2 and the inlet system 9, and ventilate for 5 minutes;

[0122] (b) Close the air inlet valve 8-2 and the air inlet system 9, open the air outlet valve 8-3 and the vacuum system 16, and evacuate the air until the pressure in the horizontal pipe 5 is below 100 Pa.

[0123] The GDMS analysis results of the tellurium product obtained in this example are shown in Table 4. It can be seen that the impurity content of the tellurium product obtained in this example is significantly reduced compared to the raw material, reaching the 6N level. The units in Table 4 are ppbw.

[0124] Table 4 Statistics of impurity content of high-purity tellurium obtained in Example 3 (unit: ppbw)

[0125] element Mg Al Ca Fe Ni Cu Zn Se Ag Cd Pb As S Tellurium raw materials 57 96 72 107 28 125 38 179 36 34 53 37 45 standard <50 <50 <100 <50 <50 <10 <100 <100 <10 <50 <50 / / Example 3 <1 <5 6 <0.5 <0.5 <1 2.6 56 <1 <5 <5 <1 4.5

[0126] Example 4

[0127] The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes a horizontal tube 5 ; one end of the horizontal tube 5 is closed, and the other end is sealed by a sealing valve 10 ; an air outlet 13 is provided at one end of the sealing valve 10 ; the horizontal tube 5 is connected to a vacuum pumping system 16 via the air outlet 13 ;

[0128] Outside the horizontal pipe 5, from the closed end to the sealing valve 10 end, there are sequentially provided a first heater 1-1, a second heater 1-2, and a heat preservation cover 19, which correspond to the first heating zone, the second heating zone, and the heat preservation zone respectively;

[0129] Inside the horizontal tube 5, from the closed end to the sealing valve 10 end, there are sequentially provided a graphite sleeve 4, a primary condenser 6, and a secondary condenser 7; the graphite sleeve 4 is located in the first heating zone, and the secondary condenser 7 is located in the insulation zone;

[0130] In this embodiment, the first heater 1-1 and the second heater 1-2 are spaced 10 mm apart, corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser 6 extends from the transition zone to the insulation zone.

[0131] The graphite boat 3 is located in the first heating zone, and the tellurium material 2 is placed in the graphite boat 3. The graphite boat 3 is 550 mm long, the graphite sleeve 4 is 650 mm long, the first-stage condenser 6 is 750 mm long, and the second-stage condenser 7 is 800 mm long.

[0132] The horizontal tube 5 is also provided with an air inlet 12, through which the horizontal tube 5 is connected to an air inlet system 9 providing an inert atmosphere; an air inlet valve 8-2 is provided between the air inlet 12 and the air inlet system 9, and an air outlet valve 8-3 is provided between the air outlet 13 and the vacuum system 16.

[0133] The vacuum pumping system 16 is connected to the tail gas treatment system 17 .

[0134] The impurity content of the graphite boat 3 and the graphite sleeve 4 is below 5 ppm.

[0135] The inert gas provided by the air intake system 9 has a purity of 6N or above.

[0136] The horizontal tube 5 in this embodiment is made of stainless steel.

[0137] The method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation in this embodiment includes the following steps:

[0138] (S1) Charging: Weigh 5.0 kg of 5N tellurium material and place it into the graphite boat 3, which is then placed into the graphite sleeve 4; close the sealing valve 10;

[0139] (S2) Vacuuming: Inert gas is introduced into the horizontal tube 5 through the air intake system 9 to replace the air in the horizontal tube 5; the air intake valve 8-2 is closed, the air outlet valve 8-3 is opened, and the vacuum degree in the horizontal tube 5 is controlled to 10 by the vacuuming system 16. -2 Below Pa;

[0140] (S3) Distillation: A two-stage distillation is performed: during the first stage of distillation, the temperature of the first heater is 430° C., and the temperature of the second heater is 350° C.; the first stage of distillation lasts for 2 hours; during the second stage of distillation, the temperature of the first heater is 520° C., and the temperature of the second heater is 350° C.; the second stage of distillation lasts for 3.5 hours. After distillation, the tellurium in the graphite boat 3 is fully volatilized and fully condensed in the primary condenser 6, low-boiling substances are condensed in the secondary condenser 7, and high-boiling substances remain in the graphite boat 3, thereby achieving effective separation of tellurium from impurity elements.

[0141] (S4) Sampling; after the distillation is completed, turn off the heating power supply; when the temperature drops below 200°C, turn off the vacuum system, open the air intake system 9 and the air intake valve 8-2 to form an inert atmosphere with a slightly positive pressure in the horizontal tube 5; after the temperature drops to room temperature, close the air intake system 9, the air intake valve 8-2 and the air outlet valve 8-3, open the sealing valve 10, and take out the secondary condenser 7, the primary condenser 6, and the graphite sleeve 4 in turn; the crystallized tellurium is located in the primary condenser 6, and high-purity tellurium is obtained.

[0142] In step (S2), process (a) and process (b) are alternately performed twice to replace the air in the horizontal tube 5 with the inert gas; that is, (a)-(b)-(a)-(b) are performed in sequence; wherein:

[0143] (a) Close the outlet valve 8-3 and the vacuum system 16, open the inlet valve 8-2 and the inlet system 9, and ventilate for 10 minutes;

[0144] (b) Close the air inlet valve 8-2 and the air inlet system 9, open the air outlet valve 8-3 and the vacuum system 16, and evacuate the air until the pressure in the horizontal pipe 5 is below 100 Pa.

[0145] The GDMS analysis results of the tellurium product obtained in this example are shown in Table 5. It can be seen that the impurity content of the tellurium product obtained in this example is significantly reduced compared to the raw material, reaching the 6N level. The units in Table 5 are ppbw.

[0146] Table 5 Statistics of impurity content of high-purity tellurium obtained in Example 4 (unit: ppbw)

[0147] element Mg Al Ca Fe Ni Cu Zn Se Ag Cd Pb As S Tellurium raw materials 62 91 65 109 38 118 29 191 28 36 48 38 36 standard <50 <50 <100 <50 <50 <10 <100 <100 <10 <50 <50 / / Example 4 5 <5 9 <0.5 <0.5 4 <1 68 <1 <5 <5 <1 2.8

Claims

1. A production device for preparing 6N high-purity tellurium by horizontal vacuum distillation, characterized in that: It comprises a horizontal tube (5); one end of the horizontal tube (5) is closed, and the other end is sealed by a sealing valve (10); one end of the sealing valve (10) is provided with an air outlet (13); the horizontal tube (5) is connected to a vacuum pumping system (16) via the air outlet (13); Outside the horizontal tube (5), from the closed end to the sealing valve (10) end, a first heater (1-1), a second heater (1-2), and a heat preservation cover (19) are sequentially provided, corresponding to the first heating zone, the second heating zone, and the heat preservation zone, respectively; Inside the horizontal tube (5), from the closed end to the sealing valve (10) end, a graphite sleeve (4), a first-level condenser (6), and a second-level condenser (7) are sequentially provided; the graphite sleeve (4) is located in the first heating zone, the second-level condenser (7) is located in the heat preservation zone, and the first-level condenser (6) extends from the first heating zone to the heat preservation zone; the graphite sleeve (4) is 50-100 mm longer than the graphite boat (3); the first-level condenser (6) is 700-800 mm long; A graphite boat (3) is placed in the first heating zone corresponding to the first heater (1-1), and the first heater (1-1) mainly plays the role of controlling the temperature of the distillation zone; a first-stage condenser is placed in the second heating zone corresponding to the second heater (1-2), and the second heater mainly plays the role of controlling the condensation effect of the first-stage condenser There is a gap of less than 20 mm between the first heater (1-1) and the second heater (1-2), corresponding to the transition zone between the first heating zone and the second heating zone; the first-level condenser (6) extends from the first heating zone to the heat preservation zone, or extends from the transition zone to the heat preservation zone; The graphite boat (3) is located in the first heating zone; the tellurium material (2) is loaded in the graphite boat (3); The horizontal tube (5) is further provided with an air inlet (12), and the horizontal tube (5) is connected to an air inlet system (9) providing an inert atmosphere through the air inlet (12); an air inlet valve (8-2) is provided between the air inlet (12) and the air inlet system (9), and an air outlet valve (8-3) is provided between the air outlet (13) and the vacuum pumping system (16).

2. The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation according to claim 1, characterized in that: There is a gap of 5 to 10 mm between the first heater (1-1) and the second heater (1-2).

3. The production apparatus for preparing 6N high-purity tellurium by horizontal vacuum distillation according to claim 1 or 2, characterized in that: The secondary condenser (7) is 700-800 mm long; the graphite boat (3) is 500-600 mm long.

4. The production device for preparing 6N high-purity tellurium by horizontal vacuum distillation according to any one of claims 1 to 3, characterized in that: The vacuum pumping system (16) is connected to the tail gas treatment system (17); the graphite boat (3) and the graphite sleeve (4) have an impurity content of less than 5 ppm; the inert gas provided by the air intake system (9) has a purity of more than 6N.

5. A method for producing 6N high-purity tellurium by horizontal vacuum distillation using the production apparatus for producing 6N high-purity tellurium by horizontal vacuum distillation according to any one of claims 1 to 4, characterized in that: Before starting vacuum distillation, the vacuum degree in the horizontal tube (5) is controlled to 10 -2 Below Pa; Two-stage distillation is adopted: the temperature of the first heater in the first distillation is 400~450℃, and the temperature of the second heater is 350~400℃; the time of the first distillation is 1~2 hours; the temperature of the first heater in the second distillation is 480~530℃, and the temperature of the second heater is 300~350℃; the time of the second distillation is 2~4 hours.

6. The method for preparing 6N high-purity tellurium by horizontal vacuum distillation according to claim 5, characterized in that: The following steps are involved: (S1) Charging: Weigh the tellurium material, put it into the graphite boat (3), and place the graphite boat (3) into the graphite sleeve (4); close the sealing valve (10); (S2) Vacuuming: Introduce inert gas into the horizontal tube (5) through the air intake system (9) to replace the air in the horizontal tube (5); close the air intake valve (8-2), open the air outlet valve (8-3), and control the vacuum degree in the horizontal tube (5) to 10 by the vacuum system (16). -2 Below Pa; (S3) distillation: performing the two-stage distillation; (S4) Sampling; After the distillation is completed, the heating power is turned off, and after the temperature drops to room temperature, the crystallized tellurium located in the first-stage condenser (6) is obtained.

7. The method for preparing 6N high-purity tellurium by horizontal vacuum distillation according to claim 6, characterized in that: In step (S2), process (a) and process (b) are alternately performed to replace the air in the horizontal tube (5) with an inert gas: (a) Close the outlet valve (8-3) and the vacuum system (16), and open the inlet valve (8-2) and the inlet system (9); (b) Close the air inlet valve (8-2) and the air inlet system (9), and open the air outlet valve (8-3) and the vacuum system (16).

8. The method for preparing 6N high-purity tellurium by horizontal vacuum distillation according to claim 6 or 7, characterized in that: In step (S4), after the heating power is turned off, the temperature is lowered to below 200°C, the vacuum system is turned off, and the air intake system (9) and the air intake valve (8-2) are opened to form a slightly positive pressure inert atmosphere in the horizontal tube (5).

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