A method and equipment for preparing high-purity tellurium using 4N high-selenium distilled tellurium.

Abstract

This invention discloses a method and equipment for preparing high-purity tellurium from 4N high-selenium distilled tellurium. The method uses 4N high-selenium distilled tellurium as raw material and proceeds through seven steps: raw material preparation, gas replacement, hydrogen distillation, directional solidification, purging and cooling, product unloading, and sampling and packaging to obtain 6N high-purity tellurium. This invention addresses the problem of high selenium (approximately 20 ppm) and high sodium (approximately 10 ppm) content in 4N high-selenium distilled tellurium. Utilizing the structural characteristics of a horizontal furnace, it integrates atmospheric distillation, hydrogen deselenization, and directional solidification into a single process by modifying the traditional condenser structure, demonstrating a novel approach. The condenser boat structure design, combined with the "secondary vaporization-condensation" process, achieves a "gas-gas" reaction effect, effectively expanding the contact area for the hydrogenation reaction compared to conventional "gas-liquid" reactions. This reduces both selenium and sodium impurities to <0.01 ppm, effectively improving the direct recovery rate of the high-purity tellurium preparation system from high-selenium tellurium raw materials. This invention offers advantages such as short production cycle, large single-furnace capacity, wide applicability, and high economic value.

Description

Technical Field

[0001] This application relates to the field of high-purity material preparation, and in particular to a method and equipment for preparing high-purity tellurium from 4N high-selenium distilled tellurium. Background Technology

[0002] Tellurium is a rare and dispersed metallic element with atomic number 52, located in the fifth period, group VI, and its element symbol is Te. It constitutes only 0.00005% of the Earth's crust and is a good semiconductor material. In the metallurgical field, it is mainly used as an alloying additive; in the petrochemical field, it is mainly used as a petroleum cracking catalyst; in the optoelectronic field, it can be used to prepare solar cells and infrared detectors; and in the optical field, it can be used to prepare infrared optical materials.

[0003] High-purity tellurium refers to elemental tellurium with a tellurium mass fraction of not less than 99.999%. High-purity tellurium is mainly used in the preparation of: cadmium telluride (CdTe) thin-film solar cells, cadmium zinc telluride (CdZnTe, CZT) room-temperature nuclear radiation detectors, mercury cadmium telluride (MCT) far-infrared detectors, thermoelectric refrigeration (or thermoelectric power generation) materials, and infrared optical materials. The current People's Republic of China nonferrous metals industry standard YS / T 817-2012 classifies high-purity tellurium into two grades based on its chemical composition: Te99.999 and Te99.9999.

[0004] The preparation processes for high-purity tellurium mainly include chemical and physical methods. The chemical method primarily employs electrolytic refining, which utilizes the difference in chemical potential between the main element tellurium and impurity elements to purify tellurium. However, due to limitations in the process principle, impurities are introduced during preparation, making it difficult to achieve a product purity higher than the 5N level.

[0005] Physical methods mainly employ vacuum distillation and hydrogen-bearing zone melting. Vacuum distillation utilizes the difference in saturated vapor pressure and volatilization rate between the main element tellurium and impurity elements to enrich the impurity elements in the distillation head and tail, thereby achieving tellurium purification. This method has a wide range of applications and high production efficiency, but it is less effective at separating impurity elements with similar physical properties to tellurium or those in the same group as tellurium.

[0006] The hydrogen-assisted zone melting method utilizes the difference in solubility of various impurity elements in solid and liquid tellurium to alter their distribution within the zone-melted tellurium ingot. This is supplemented by introducing high-purity hydrogen gas into the molten zone, thereby reducing the selenium content and producing high-purity tellurium. This method is commonly used to prepare 7N ultra-high-purity tellurium and 6N high-purity tellurium, but it suffers from high energy consumption, long production cycles, and particularly high requirements for raw materials (generally requiring 5N or higher). Limited by the zone melting principle, the molten zone capable of contacting hydrogen gas and participating in the hydrogenation reaction is relatively narrow, and it is a gas-liquid interface reaction, resulting in limited actual deselection efficiency.

[0007] Hydrogen selenide can be prepared by the direct combination of hydrogen and selenium at temperatures ranging from 523.15 K to 843.15 K. The amount of hydrogen selenide in the reaction mixture is highest (over 50%) at 843.15 K; above this temperature, the proportion of hydrogen selenide decreases. The reaction equation is as follows:

[0008]

[0009] 4N high-selenium distilled tellurium refers to the byproduct of vacuum distillation for producing 5N and 6N high-purity tellurium from 4N tellurium ingots. This distilled tellurium is enriched with low-boiling impurities such as selenium and sodium, typically around 20 ppm selenium and 10 ppm sodium, while the tellurium content is at the 4N5 level. Due to its high selenium and sodium content, it is unsuitable for conventional processing methods such as vacuum distillation and hydrogen-bearing zone melting in production. Therefore, it must be returned to the upstream tellurium smelting system for further processing.

[0010] Chinese patent CN107313063A discloses a method for smelting 5N high-purity tellurium. This method first uses a low-current-density electrodeposition method to produce 4N tellurium ingots conforming to the YS / T222-2010 standard. Then, the 4N tellurium is subjected to low-temperature vacuum distillation. Finally, the distilled tellurium is crushed into small particles, which are then placed in a pure quartz crucible and heated in a hydrogen atmosphere to cast 5N high-purity tellurium ingots. This technical solution has limited deselection efficiency. Chinese patent CN106517106A discloses a highly efficient purification method for high-purity tellurium. This method first uses a chemical method to purify industrial tellurium powder to 3N-4N, then melts it in a hydrogen atmosphere, and finally uses a Czochralski purification method to obtain 5N-6N high-purity tellurium. This technical solution relies on a gas-liquid interface reaction for hydrogen deselection, which has a low reaction rate and limited practical effect. The chemical method generates a significant amount of waste, and the Czochralski purification method is difficult to operate and has poor purification results.

[0011] Chinese patent CN212832850U discloses a high-efficiency laboratory refining apparatus for removing selenium in tellurium refining. This apparatus includes a refining furnace, crucible, stirring paddle, air inlet pipe, casting chamber, condenser, vacuum device, and exhaust gas absorption device. In this high-efficiency laboratory refining apparatus, the components in contact with molten tellurium extensively use 316L stainless steel and Hastelloy alloys, which can lead to contamination of the liquid tellurium by various impurity elements, reducing product quality. Furthermore, this equipment suffers from complex assembly, high failure rate, and reliance on a single source of raw materials.

[0012] Chinese patent CN113387336B discloses a method for removing selenium from tellurium ingots. This method employs a three-stage, precisely temperature-controlled process to remove selenium from tellurium ingots, featuring a short process cycle and minimal tellurium loss. This method uses 4N tellurium (Se≤20ppm) as raw material to prepare 5N tellurium, with a processing capacity of 4 kg / furnace and a processing efficiency of approximately 0.5 kg / h, reducing selenium from 20ppm to below 2ppm. However, it claims to simultaneously reduce impurities such as lead, bismuth, sodium, and silicon to below 1ppm and impurities such as copper, magnesium, and arsenic to below 0.5ppm by simply placing the tellurium ingot in a graphite boat for melting and hydrogen permeation to remove selenium. The author believes this is difficult to achieve under the disclosed process conditions. Furthermore, the selenium removal relies on a gas-liquid interface reaction, resulting in relatively low actual efficiency.

[0013] Chinese patent CN116121847A discloses a method and production apparatus for preparing ultra-high purity tellurium by zone melting, as well as other similar process schemes for preparing high purity tellurium using hydrogen-driven zone melting. These processes have high requirements for raw materials, generally not lower than 5N and Se≤1ppm. Hydrogen-driven deselection relies on the "gas-liquid" interface reaction, and the melting zone that can contact hydrogen and participate in the hydrogenation reaction is relatively narrow. The actual reaction rate is low, the deselection effect is limited, the production cycle is long, the cost is high, and it is not suitable for processing low-quality materials.

[0014] Chinese patent CN217458841U discloses a device for deselenization and purification of high-selenium tellurium to prepare high-purity tellurium. This device employs an induction heating coil array, coupled with a control system, to simulate multi-zone series melting, directional solidification, and hydrogen deselenization processes, enabling efficient removal of selenium from tellurium. Specifically, it can prepare 6N high-purity tellurium from 5N tellurium (Se≤10ppm) as raw material. However, limited by the melt purification principle, it has high allowable upper limits for the content of impurities other than selenium in the input raw material, generally not lower than the 5N standard; otherwise, the purification effect cannot be guaranteed. Therefore, this device cannot efficiently remove sodium from 4N high-selenium distilled tellurium.

[0015] Chinese patent CN107585745A discloses a process for producing 5N tellurium. This process first screens the raw materials, selecting only 4N tellurium with a selenium content ≤15ppm. Then, it pre-treats the raw materials using hydrogenation to reduce selenium and slag formation to reduce sodium, controlling the selenium content to <3ppm and the sodium content to <0.8ppm. The raw materials then undergo vacuum distillation to ultimately produce high-purity 5N tellurium, i.e., Se≤2ppm and Na≤0.5ppm. While this process is capable of processing 4N high-selenium distilled tellurium, it also suffers from problems such as a complex process flow, long processing cycle, and low and incomplete selenium removal efficiency.

[0016] Chinese patent CN110894065B discloses an apparatus and method for preparing high-purity tellurium. The apparatus includes a vacuum distillation unit, a vacuum pumping unit, a hydrogen purification and circulation unit, a high-frequency induction heating unit, and a product collection unit. This method uses 5N tellurium (Se≤1.5ppm) as raw material to prepare 6N high-purity tellurium, with a processing capacity of 5 kg / furnace and a processing efficiency of approximately 0.2 kg / h, reducing selenium concentration from 1.5 ppm to below 0.2 ppm. However, this technology involves complex equipment combinations, low single-furnace processing capacity, and relies on a gas-liquid interface reaction for low selenium removal efficiency, making it unsuitable for industrial production.

[0017] Currently, there are no publicly available methods or equipment in the industry that can efficiently process 4N high-selenium distilled tellurium, which is enriched with a large amount of low-boiling impurities such as selenium and sodium, and prepare high-purity tellurium. Summary of the Invention

[0018] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method and equipment for preparing high-purity tellurium that can efficiently remove selenium and sodium from 4N high-selenium distilled tellurium, with a simple process flow and a large single-furnace processing capacity.

[0019] The technical solution adopted by this invention to solve its technical problem is: a method for preparing high-purity tellurium from 4N high-selenium distilled tellurium, comprising the following process steps:

[0020] Step 1: Load an appropriate amount of 4N high-selenium distilled tellurium raw material, which has been crushed to a suitable particle size, into the raw material boat, place it in the designated process position inside the hydrogen distillation tube, and load it into the condenser boat and push it to the constriction of the hydrogen distillation tube. Place a quartz gasket below the narrow end of the condenser boat and install the cap of the hydrogen distillation tube onto the flange at the head of the hydrogen distillation tube.

[0021] Step 2: Adjust the output partial pressure of high-purity argon and high-purity hydrogen to 0.1MPa~0.2MPa, adjust the high-purity argon float flowmeter to make the flow rate of high-purity argon gas 10L / min~20L / min, purge for 1 hour, then turn off the high-purity argon float flowmeter, adjust the high-purity hydrogen float flowmeter to make the flow rate of high-purity hydrogen gas 15L / min~20L / min, and purge for 1 hour.

[0022] Step 3: Set the temperature of each zone to 500K and turn on the heating switch. After reaching the temperature, maintain the temperature for 0.5 hours. Set the temperatures of the first, second, third, and fourth zones to 550K~800K, 800K~1000K, 1000K~1300K, and 650K~750K, respectively. After reaching the temperature, maintain the temperature for 0.5 hours. Set the temperature of the fourth zone to 900K~1300K. After reaching the temperature, start the hydrogen distillation process and maintain the temperature for 12 hours~16 hours.

[0023] The distillation process utilizes the difference in saturated vapor pressure between the main element tellurium and various impurity elements. Impurities with a higher saturated vapor pressure than tellurium preferentially evaporate into the gas phase and then condense in a lower temperature region; impurities with a lower saturated vapor pressure enter the gas phase in small quantities, but the majority remain in the distillation feed. This allows for the distillation purification of tellurium. Specifically, during distillation, tellurium in the feed boat is heated and vaporized, entering the gas phase and mixing with hydrogen. It then passes through a transition section and condenses into a liquid in a condensation boat; this process is known as "single vaporization-condensation." However, because the temperatures in the feed section (fourth temperature zone) and the transition section (third temperature zone) are much higher than 843.15 K, the yield of hydrogen selenide is low during this process, resulting in minimal actual selenium removal. It primarily serves to separate high-boiling-point impurities and non-selenium low-boiling-point impurities.

[0024] The condensed liquid tellurium in the condenser boat, primarily composed of low-boiling-point compounds in the high-temperature zone (second temperature zone), re-vaporizes and enters the gas phase to fully mix with hydrogen, achieving a gas-gas reaction and effectively expanding the contact area for the hydrogenation reaction. This is supplemented by the contact between hydrogen and the upper surface of the liquid tellurium at the vapor-liquid interface within the condenser boat. Both factors jointly promote the reaction of selenium in tellurium with hydrogen to generate hydrogen selenide, which leaves the system with the exhaust gas. The re-vaporized tellurium then re-condenses into a liquid state in the low-temperature zone (first temperature zone) within the condenser boat. Unreacted selenium in the liquid tellurium diffuses to the high-temperature zone and the vapor-liquid interface to participate in the aforementioned reactions, forming a small-scale deselenization cycle within the condenser. This process, known as "secondary vaporization-condensation," plays a crucial role in achieving the deselenization effect of this process equipment.

[0025] Step 4: Set the process temperatures for the first, second, third, and fourth temperature zones to 350K~550K, 700K~900K, 700K~900K, and 350K~550K respectively. After the temperatures in the first and fourth zones drop to 550K, turn off the heating switch to start the directional solidification process. After the temperatures in the second and third temperature zones drop to 650K, remove the removable insulation material between the two heating furnace jackets.

[0026] Finally, a directional solidification process is adopted during the cooling process, so that impurities such as magnesium and iron are concentrated in the head region of the product tellurium ingot, and impurities such as selenium and sodium are concentrated in the tail region of the product tellurium ingot, thereby further improving product quality.

[0027] Step 5: After the temperature readings of each temperature zone are all less than 550K, turn off the high-purity hydrogen float flow meter and adjust the high-purity argon float flow meter so that the flow rate of high-purity argon gas is 10L / min to 20L / min to help the hydrogen distillation device cool down naturally.

[0028] Step 6: After the temperature of each zone drops to room temperature, turn off the high-purity argon float flow meter, remove the cap of the hydrogen distillation tube, first take out the condenser boat and place it in the product transfer box, then take out the raw material boat and place it in the distillation bottom material transfer box.

[0029] Step 7: Take out the 6N high-purity tellurium product from the condensation boat, and according to the grain boundary pattern on the surface of the produced tellurium ingot, remove the head and tail and take samples, weigh them, vacuum pack them, number them and store them.

[0030] A device for preparing high-purity tellurium from 4N high-selenium distilled tellurium includes a hydrogen distillation unit connected to a gas source unit and a tail gas collection unit. The hydrogen distillation unit contains two sets of heating furnace sleeves, with a hydrogen distillation tube between them. The heating furnace sleeves contain removable insulation material. The outer wall of the hydrogen distillation unit is equipped with a heating switch and a temperature control switch. Multiple thermocouples are spaced apart from left to right on the heating furnace sleeves. A transformer is located at the bottom of the hydrogen distillation unit. The cap of the hydrogen distillation tube is connected to the flange at the head of the hydrogen distillation tube. The cap of the hydrogen distillation tube has an outlet, and the tail of the hydrogen distillation tube has an inlet. A condenser boat is located on one side of the head of the hydrogen distillation tube, with a quartz gasket below the narrow end of the condenser boat. High-purity tellurium product is placed inside the condenser boat. A raw material boat is located on one side of the tail of the hydrogen distillation tube, containing 4N high-selenium distilled tellurium raw material.

[0031] Preferably, the gas source device is used to provide an oxygen-free environment and a hydrogen reduction environment for the production process, including an external high-purity gas delivery pipeline. The high-purity gas delivery pipeline connects the external high-purity gas source to the inlet ports of the hydrogen float flow meter and the argon float flow meter. The hydrogen float flow meter and the argon float flow meter are fixed to the outer wall of the tail end of the hydrogen distillation device. The gas source tee connects the outlet ports of the hydrogen float flow meter and the argon float flow meter to the inlet of the hydrogen distillation pipe.

[0032] Preferably, the exhaust gas collection device is used to collect process exhaust gas generated during the production process, including a hydrogen distillation exhaust gas pipe, the hydrogen distillation exhaust gas pipe connecting the outlet of the hydrogen distillation pipe cap to the inlet of the gas washing bottle, the gas washing bottle containing pure water, the gas washing bottle exhaust gas pipe connecting the outlet of the gas washing bottle to the port of the exhaust gas main pipe, and the port of the exhaust gas main pipe connecting to the external process exhaust gas main pipe.

[0033] Preferably, the heating furnace jacket adopts resistance heating or electromagnetic induction heating;

[0034] Preferably, the removable insulation material is made of aluminum silicate or insulation cotton.

[0035] Preferably, the heating furnace jacket has four temperature zones, and each temperature zone is equipped with a thermocouple;

[0036] Preferably, the hydrogen distillation tube, the hydrogen distillation tube cap, the condenser boat, and the raw material boat are made of high-purity quartz.

[0037] Preferably, the high-purity gas delivery pipeline is made of 316L stainless steel;

[0038] Preferably, the hydrogen distillation tailpipe and the gas washing bottle tailpipe are made of polytetrafluoroethylene propylene.

[0039] The beneficial effects of this invention are:

[0040] 1) Compared with existing high-purity tellurium preparation technologies, this invention can achieve efficient sodium removal and deep selenium removal from 4N high-selenium distilled tellurium materials to directly prepare 6N high-purity tellurium, thereby improving the direct recovery rate of the high-purity tellurium preparation system and reducing the waste of tellurium materials.

[0041] 2) Compared with existing process technologies that can process 4N high-selenium distilled tellurium materials, this invention has advantages such as simple process flow, simple equipment, short production cycle, large single furnace processing capacity (processing capacity is 20kg / furnace, processing efficiency is about 1kg / h), and less waste.

[0042] 3) This invention addresses the problem of high selenium (approximately 20 ppm) and high sodium (approximately 10 ppm) tellurium in 4N high-selenium distillate. By utilizing the structural characteristics of a horizontal furnace and improving the traditional condenser structure, this invention integrates three high-purity material preparation processes—atmospheric distillation, hydrogen deselenization, and directional solidification—through three main processes: two "vaporization-condensation" steps and cooling. This approach is novel.

[0043] 4) This invention relates to a "secondary vaporization-condensation" process, which enables high-selenium tellurium to enter the gas phase in the condenser and mix fully with hydrogen to achieve a "gas-gas" reaction effect. Compared with conventional methods, which simply make hydrogen and liquid tellurium interface contact each other, this method can effectively expand the contact area of ​​the hydrogenation reaction, thereby achieving deep removal of selenium and reducing selenium from 20 ppm to below 0.01 ppm.

[0044] 5) This invention has low requirements for raw materials, a wide range of applications, and can also meet the requirements for preparing high-purity tellurium or other high-purity materials from other types of raw materials. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0046] Parts Description: 1. Hydrogen distillation apparatus; 101. Gas inlet; 102. Raw material; 103. Hydrogen distillation tube; 104. Heating furnace jacket; 105. Raw material boat; 106. Thermocouple; 1061. First temperature zone; 1062. Second temperature zone; 1063. Third temperature zone; 1064. Fourth temperature zone; 107. Temperature control switch; 108. Condensation boat; 109. Removable insulation material; 110. Product; 111. Stone 1. Gasket; 112. Hydrogen distillation tube cap; 113. Gas outlet; 114. Heating switch; 115. Transformer; 2. Gas source device, 201. High-purity gas delivery pipeline; 202. Argon float flowmeter; 203. Hydrogen float flowmeter; 204. Gas source tee; 3. Tail gas collection device, 301. Hydrogen distillation tail gas pipe; 302. Gas washing bottle; 303. Gas washing bottle tail gas pipe; 304. Tail gas main pipe port. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] Example 1:

[0049] A device for preparing high-purity tellurium by distilling 4N high-selenium tellurium includes a hydrogen distillation apparatus 1. The hydrogen distillation apparatus 1 includes a heating furnace sleeve 104, removable insulation material 109, a heating switch 114, a thermocouple 106, a transformer 115, a temperature control switch 107, a hydrogen distillation tube 103, a hydrogen distillation tube cap 112, a condenser boat 108, a quartz gasket 111, and a raw material boat 105. The furnace body of the hydrogen distillation apparatus 1 is placed horizontally on the ground. The two heating furnace sleeves 104 are fixed to the furnace body of the hydrogen distillation apparatus 1. The removable insulation material 109 is located between the two heating furnace sleeves 104. The heating switch 114 is fixed to the outer wall of the furnace body of the hydrogen distillation apparatus 1. The thermocouple 106 penetrates the outer wall of the heating furnace sleeve 104. The transformer 115 is fixed to the outer wall of the furnace body. The temperature control switch 107 is fixed to the outer wall of the hydrogen distillation apparatus 1 at the bottom of the furnace body. The hydrogen distillation tube 103 is located in two heating furnace sleeves 104. The hydrogen distillation tube 103 has a flange at the head and an air inlet 101 at the tail. The hydrogen distillation tube cap 112 is connected to the flange at the head of the hydrogen distillation tube 103 by a rubber sealing ring and bolts. The head of the hydrogen distillation tube cap 112 has an air outlet 113. The condenser boat 108 is placed inside the hydrogen distillation tube 103 on one side of the head and contains high-purity tellurium 110. The quartz gasket 111 is placed below the narrow end of the condenser boat 108. The raw material boat 105 is placed inside the hydrogen distillation tube 103 on one side of the tail and contains 4N high-selenium distilled tellurium 102.

[0050] The gas source device 2 is used to provide an oxygen-free environment and a hydrogen reduction environment for the production process. It includes an external high-purity gas delivery pipeline 201, a hydrogen float flowmeter 203, an argon float flowmeter 202, and a gas source tee 204. The high-purity gas delivery pipeline 201 connects the external high-purity gas source to the inlet ports of the hydrogen float flowmeter 203 and the argon float flowmeter 202. The hydrogen float flowmeter 203 and the argon float flowmeter 202 are fixed to the outer wall of the tail end of the hydrogen distillation device 1. The gas source tee 204 connects the outlet ports of the hydrogen float flowmeter 203 and the argon float flowmeter 202 to the inlet port 101 at the tail end of the hydrogen distillation pipe 103.

[0051] The exhaust gas collection device 3 is used to collect the process exhaust gas generated during the production process. It includes a hydrogen distillation exhaust gas pipe 301, a gas washing bottle 302, a gas washing bottle exhaust gas pipe 303, and an exhaust gas main pipe port 304. The hydrogen distillation exhaust gas pipe 301 connects the outlet 113 of the hydrogen distillation pipe to the inlet of the gas washing bottle 302. The gas washing bottle 302 is filled with pure water. The gas washing bottle exhaust gas pipe 303 connects the outlet of the gas washing bottle 302 to the exhaust gas main pipe port 304. The exhaust gas main pipe port 304 is connected to an external process exhaust gas main pipe.

[0052] A method for preparing high-purity tellurium from 4N high-selenium distilled tellurium includes the following process steps:

[0053] 20 kg of 4N high-selenium distilled tellurium 102, crushed to a suitable particle size, is loaded into the raw material boat 105 and placed in the designated process position inside the hydrogen distillation tube 103. The material is then loaded into the condenser boat 108 and pushed to the constriction point of the hydrogen distillation tube 103. A quartz gasket 111 is placed below the narrow end of the condenser boat 108. The cap 112 of the hydrogen distillation tube is installed at the flange at the head of the hydrogen distillation tube 103. The output partial pressures of high-purity argon and high-purity hydrogen are adjusted to 0.2 MPa, and the high-purity argon float flowmeter 202 is adjusted to ensure a high-purity argon gas flow rate of 15 L. After purging for 1 hour, turn off the high-purity argon float flowmeter 202 and adjust the high-purity hydrogen float flowmeter 203 to make the high-purity hydrogen gas flow rate 20 L / min. Purge for 1 hour. Set the temperature of each zone to 500 K, turn on the heating switch 114, and hold the temperature for 0.5 hours after reaching the set temperature. Set the temperatures of the first, second, third, and fourth zones to 620 K, 920 K, 1150 K, and 720 K, respectively. Hold the temperature for 0.5 hours after reaching the set temperature. Set the temperature of the fourth zone to 1150 K, and start purging after reaching the set temperature. The hydrogen distillation process was operated at a constant temperature for 16 hours. The process temperatures for the first, second, third, and fourth temperature zones were set to 400K, 800K, 800K, and 400K, respectively. After the first and fourth temperature zones dropped to 550K, the heating switch 114 was turned off, and the directional solidification process began. After the second and third temperature zones dropped to 650K, the removable insulation material 109 between the two heating furnace jackets 104 was removed. After the temperature readings of each temperature zone were all below 550K, the high-purity hydrogen float flowmeter 203 was turned off, and the high-purity argon float flowmeter was adjusted. Set the flow rate of high-purity argon gas to 15 L / min to allow the furnace body of the auxiliary hydrogen distillation device 1 to cool naturally. Once the temperature of each zone has dropped to room temperature, turn off the high-purity argon gas float flowmeter 202, remove the cap 112 of the hydrogen distillation tube, first take out the condenser boat 108 and place it in the product transfer box, then take out the raw material boat 105 and place it in the distillation bottom material transfer box. Take out the 6N high-purity tellurium product 110 from the condenser boat 108, and according to the grain boundary pattern on the surface of the produced tellurium ingot, remove the head and tail and take samples. Weigh them, vacuum package them, number them and store them.

[0054] The current People's Republic of China nonferrous metals industry standard YS / T 817-2012 classifies high-purity tellurium into two grades based on its chemical composition: Te99.999 and Te99.9999.

[0055] The table below compares the main impurity element content requirements for the two grades Te99.999 and Te99.9999 in the current People's Republic of China nonferrous metals industry standard YS / T 817-2012 with the test results of the raw material 4N high-selenium distilled tellurium and the product 6N high-purity tellurium ingot in Example 1. Both the raw material and the product were tested by inductively coupled plasma mass spectrometry (ICP-MS) (unit: ppm).

[0056] Based on the test results, the method and equipment for preparing high-purity tellurium using 4N high-selenium distilled tellurium as described in this invention can achieve the preparation of 6N high-purity tellurium ingots using 4N high-selenium distilled tellurium as raw material through atmospheric pressure hydrogen distillation and directional solidification cooling.

[0057]

[0058] Example 2

[0059] 15 kg of 4N high-selenium distilled tellurium 102, crushed to a suitable particle size, is loaded into the raw material boat 105 and placed in the designated process position inside the hydrogen distillation tube 103. The material is then loaded into the condenser boat 108 and pushed to the constriction point of the hydrogen distillation tube 103. A quartz gasket 111 is placed below the narrow end of the condenser boat 108. The cap 112 of the hydrogen distillation tube is installed at the flange at the head of the hydrogen distillation tube 103. The output partial pressures of high-purity argon and high-purity hydrogen are adjusted to 0.15 MPa, and the high-purity argon float flowmeter 202 is adjusted to ensure a high-purity argon gas flow rate of 20 L. After purging for 1 hour, turn off the high-purity argon float flowmeter 202 and adjust the high-purity hydrogen float flowmeter 203 to make the high-purity hydrogen gas flow rate 15 L / min. Purge for 1 hour. Set the temperature of each zone to 500 K, turn on the heating switch 114, and hold the temperature for 0.5 hours after reaching the set temperature. Set the temperatures of the first, second, third, and fourth zones to 700 K, 950 K, 1250 K, and 720 K, respectively. Hold the temperature for 0.5 hours after reaching the set temperature. Set the temperature of the fourth zone to 1120 K. After reaching the set temperature, start introducing hydrogen. The distillation process was operated at a constant temperature for 15 hours. The process temperatures for the first, second, third, and fourth temperature zones were set to 450K, 820K, 900K, and 450K, respectively. After the first and fourth temperature zones dropped to 550K, the heating switch 114 was turned off to begin the directional solidification process. After the second and third temperature zones dropped to 650K, the removable insulation material 109 between the two heating furnace jackets 104 was removed. After the temperature readings of each zone were all below 550K, the high-purity hydrogen float flowmeter 203 was turned off, and the high-purity argon float flowmeter was adjusted. The flow meter 202 is used to introduce high-purity argon gas at a flow rate of 20 L / min to help the furnace of the hydrogen distillation apparatus 1 cool down naturally. After the temperature of each zone drops to room temperature, the high-purity argon gas float flow meter 202 is turned off, the cap 112 of the hydrogen distillation tube is removed, the condenser boat 108 is taken out first and placed in the product transfer box, and then the raw material boat 105 is taken out and placed in the distillation bottom material transfer box. The 6N high-purity tellurium product 110 in the condenser boat 108 is taken out, and according to the grain boundary pattern on the surface of the produced tellurium ingot, the head and tail are removed and samples are taken. After weighing, it is vacuum packaged, numbered and stored.

[0060] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A device for preparing high-purity tellurium from 4N high-selenium distillation tellurium, comprising a hydrogen-passing distillation device (1), the hydrogen-passing distillation device (1) being connected with a gas source device (2) and a tail gas collecting device (3) respectively, characterized in that The hydrogenation distillation device (1) is provided with two heating furnace jackets (104), a hydrogenation distillation pipe (103) is arranged between the two heating furnace jackets (104), the heating furnace jacket (104) is provided with detachable heat preservation materials (109), the outer wall of the hydrogenation distillation device (1) is provided with a heating switch (114) and a temperature control switch (107), a plurality of thermocouples (106) are sequentially and spacedly arranged on the heating furnace jacket (104) from left to right, the bottom of the hydrogenation distillation device (1) is provided with a transformer (115), a hydrogenation distillation pipe cap (112) is connected with the head flange of the hydrogenation distillation pipe (103), the head of the hydrogenation distillation pipe cap (112) is provided with a gas outlet (113), the tail of the hydrogenation distillation pipe (103) is provided with a gas inlet (101), the inner head side of the hydrogenation distillation pipe (103) is provided with a condensation boat (108), the lower side of the thin diameter end of the condensation boat (108) is provided with a quartz gasket (111), high-purity tellurium products (110) are placed in the condensation boat (108), the tail side of the hydrogenation distillation pipe (103) is provided with a raw material boat (105), and 4N high-selenium distillation tellurium raw materials (102) are placed in the raw material boat (105); the gas source device (2) comprises an external high-purity gas conveying pipeline (201), the high-purity gas conveying pipeline (201) is connected with the external high-purity gas source, a hydrogen gas float flow meter (203) and an argon gas float flow meter (202) gas inlet ports, the hydrogen gas float flow meter (203) and the argon gas float flow meter (202) are fixed to the tail end outer wall of the hydrogenation distillation device (1), a gas source tee joint (204) is connected with the hydrogen gas float flow meter (203) and the argon gas float flow meter (202) gas outlet ports and the gas inlet (101) of the hydrogenation distillation pipe; the tail gas collecting device (3) comprises a hydrogenation distillation tail gas pipe (301), the hydrogenation distillation tail gas pipe (301) is connected with the gas outlet (113) of the hydrogenation distillation pipe cap and the gas inlet of a gas washing bottle (302), pure water is contained in the gas washing bottle (302), a gas washing bottle tail gas pipe (303) is connected with the gas outlet of the gas washing bottle (302) and a tail gas main pipe port (304), and the tail gas main pipe port (304) is connected with an external process tail gas main pipe.

2. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium as claimed in claim 1, wherein The heating furnace jacket (104) adopts resistance heating or electromagnetic induction heating.

3. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium according to claim 1 or 2, characterized in that The detachable heat preservation materials (109) adopt aluminum silicate or heat preservation cotton materials.

4. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium according to claim 1 or 2, characterized in that The heating furnace jacket (104) is provided with four temperature zones, and each temperature zone is provided with a thermocouple (106).

5. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium as claimed in claim 1 or 2, wherein The hydrogenation distillation pipe (103), the hydrogenation distillation pipe cap (112), the condensation boat (108) and the raw material boat (105) adopt high-purity quartz materials.

6. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium as claimed in claim 1 or 2, wherein The high-purity gas conveying pipeline (201) adopts 316L stainless steel materials.

7. The apparatus for producing high purity tellurium from 4N high selenium distillation tellurium as claimed in claim 1 or 2, wherein The hydrogenation distillation tail gas pipe (301) and the gas washing bottle tail gas pipe (303) adopt polytetrafluoroethylene materials.

8. A method for preparing high purity tellurium using the 4N high selenium distillation tellurium according to any one of claims 1-7, characterized in that The process comprises the following steps: Step one: a suitable amount of 4N high selenium distilled tellurium raw material (102) is broken to the appropriate particle size, loaded into the raw material boat (105), placed in the hydrogen distillation tube (103) at the designated process position, and loaded into the condensation boat (108) and pushed to the hydrogen distillation tube (103) neck, a quartz gasket (111) is placed below the thin end of the condensation boat (108), and the hydrogen distillation tube cap (112) is installed on the hydrogen distillation tube (103) head flange; Step two: adjust the output partial pressure of high-purity argon and high-purity hydrogen to 0.1-0.2 MPa, adjust the high-purity argon float flowmeter (202) to make the high-purity argon gas flow rate 10-20 L / min, and blow for 1 h, then close the high-purity argon float flowmeter (202), adjust the high-purity hydrogen float flowmeter (203) to make the high-purity hydrogen gas flow rate 15-20 L / min, and blow for 1 h; Step three: set the temperature of each temperature zone to 500 K, turn on the heating switch (114), and after reaching the temperature, keep it constant for 0.5 h, set the temperature of the first, second, third and fourth temperature zones to 550-800 K, 800-1000 K, 1000-1300 K and 650-750 K respectively, and after reaching the temperature, keep it constant for 0.5 h, set the temperature of the fourth temperature zone to 900-1300 K, and after reaching the temperature, start the hydrogen distillation process, and keep it constant for 12-16 h; Step four: set the process temperature of the first, second, third and fourth temperature zones to 350-550 K, 700-900 K, 700-900 K and 350-550 K respectively, after the temperature of the first and fourth temperature zones drops to 550 K, turn off the heating switch (114) and start the directional solidification process, and after the temperature of the second and third temperature zones drops to 650 K, remove the detachable insulation material (109) between the two heating furnace jackets (104); Step five: after the temperature of each temperature zone is less than 550 K, turn off the high-purity hydrogen float flowmeter (203), adjust the high-purity argon float flowmeter (202) to make the high-purity argon gas flow rate 10-20 L / min, and assist the hydrogen distillation device (1) in natural cooling; Step six: after the temperature of each temperature zone drops to room temperature, turn off the high-purity argon float flowmeter (202), remove the hydrogen distillation tube cap (112), first take out the condensation boat (108) and place it in the product transfer box, then take out the raw material boat (105) and place it in the distillation bottom material transfer box; Step seven: take out the 6N high-purity tellurium product (110) in the condensation boat (108), according to the grain boundary pattern on the top surface of the tellurium ingot, cut off the head and tail respectively and take samples, weigh them, vacuum package, number and store.

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