阅读说明：本技术 一种制备高纯碲的设备及方法 (Equipment and method for preparing high-purity tellurium ) 是由 郭学益 张磊 田庆华 李栋 许志鹏 于 2019-12-18 设计创作，主要内容包括：一种制备高纯碲的设备及方法,包括真空蒸馏装置、抽真空装置、氢气净化循环装置、高频感应加热装置和产品收集装置,所述抽真空装置用于提供真空环境,包括单孔真空抽滤机和双孔真空抽滤机,所述单孔真空抽滤机与真空蒸馏釜上的抽气口相连接；所述氢气净化循环装置用于给收集装置提供氢气还原环境。利用本发明设备制备高纯碲,流程短,能耗低,减去了常规制备高纯碲过程中碲复熔工序,避免复熔过程中所带来的高能耗和装料过程引起的局部氧化问题。(The equipment and the method for preparing the high-purity tellurium comprise a vacuum distillation device, a vacuumizing device, a hydrogen purification circulating device, a high-frequency induction heating device and a product collecting device, wherein the vacuumizing device is used for providing a vacuum environment and comprises a single-hole vacuum suction filter and a double-hole vacuum suction filter, and the single-hole vacuum suction filter is connected with a suction opening on a vacuum distillation kettle; the hydrogen purification circulating device is used for providing a hydrogen reduction environment for the collecting device. The equipment for preparing high-purity tellurium has short flow and low energy consumption, omits the tellurium remelting process in the conventional process of preparing high-purity tellurium, and avoids the problems of high energy consumption in the remelting process and local oxidation caused by the charging process.)

1. The utility model provides an equipment of preparation high-purity tellurium, includes vacuum distillation device, evacuating device, hydrogen purification circulating device and high frequency induction heating device and product collection device, its characterized in that:

the vacuum distillation device comprises a vacuum distillation kettle, more than two layers of graphite evaporation vessels, a conical condenser, an aggregate funnel and a vertical sampling detection pipe, wherein the conical condenser is fixed on the inner top wall of the vacuum distillation kettle, the aggregate funnel is positioned below the conical condenser, the graphite evaporation vessels are arranged at the bottom of the vacuum distillation kettle, the vertical sampling detection pipe penetrates through each graphite evaporation vessel, the upper end of the vertical sampling detection pipe is connected with the aggregate funnel, the lower end of the vertical sampling detection pipe penetrates through the bottom of the vacuum distillation kettle and is exposed to the outside, and an air suction port and a steam outlet are respectively formed in two side walls of the vacuum distillation kettle;

the vacuum pumping device is used for providing a vacuum environment and comprises a single-hole vacuum pumping filter and a double-hole vacuum pumping filter, wherein the single-hole vacuum pumping filter is connected with a pumping hole on the vacuum distillation kettle; preferably, a buffer tank is arranged between the vacuum suction filter and the vacuum distillation kettle;

the hydrogen purification circulating device is used for providing a hydrogen reduction environment for the product collecting device;

the product collecting device comprises a molten metal buffer kettle and a hydrogen reducing furnace, wherein the molten metal buffer kettle is connected with the steam outlet and the hydrogen reducing furnace through a molten metal conveying pipe, a graphite valve is arranged on the molten metal conveying pipe, the molten metal buffer kettle is connected with a double-hole vacuum suction filter, and the hydrogen reducing furnace is respectively connected with the double-hole vacuum suction filter and a hydrogen purifying device;

the high-frequency induction heating devices are distributed on the two sides and the top end of the vacuum distillation kettle, the inner side of the sampling monitoring pipe, the inner side of the molten metal buffer kettle and the inner side of the hydrogen reduction furnace.

2. The apparatus for producing high purity tellurium as claimed in claim 1, wherein: and a transparent observation window is arranged on the vacuum distillation kettle.

3. The apparatus for producing high-purity tellurium as claimed in claim 1 or 2, wherein: the hydrogen purification device comprises a hydrogen purifier, a gas collection steel cylinder and a rotary gas valve.

4. The apparatus for producing high-purity tellurium as claimed in claim 1 or 2, wherein: and a weight sensor is arranged at the bottom of the vacuum distillation kettle.

5. The apparatus for producing high purity tellurium as claimed in claim 3, wherein: and a weight sensor is arranged at the bottom of the vacuum distillation kettle.

6. The apparatus for producing high-purity tellurium as claimed in claim 1 or 2, wherein: the vacuum distillation kettle is internally provided with a graphite tower plate with a round hole at the middle part, and the collecting funnel is fixed in the vacuum distillation kettle through the graphite tower plate.

7. The apparatus for producing high purity tellurium as claimed in claim 3, wherein: the vacuum distillation kettle is internally provided with a graphite tower plate with a round hole at the middle part, and the collecting funnel is fixed in the vacuum distillation kettle through the graphite tower plate.

8. The apparatus for producing high purity tellurium as claimed in claim 4, wherein: the vacuum distillation kettle is internally provided with a graphite tower plate with a round hole at the middle part, and the collecting funnel is fixed in the vacuum distillation kettle through the graphite tower plate.

9. A method for producing high-purity tellurium by using the apparatus for producing high-purity tellurium set forth in claim 8, characterized in that: the method comprises the following steps:

placing a crude tellurium raw material in a clean graphite evaporation vessel, recording display data of a weight sensor, and sequentially fixing and sealing a vertical sampling detection tube, a graphite tower plate, an aggregate funnel and a conical condenser;

step two, starting a single-hole vacuum suction filter and a double-hole vacuum suction filter for vacuum treatment, so that the vacuum distillation kettle, the molten metal buffer kettle, the hydrogen reduction furnace and the connected molten metal conveying pipe are all in a vacuum state, and the vacuum degree in a set range is achieved;

step three, starting a high-frequency induction heating device, entering a primary distillation process, controlling the temperature of the interior of the vacuum distillation kettle, the conical condenser and the vertical sampling detection tube to be set temperature, keeping the temperature for set time, gradually melting the crude tellurium raw material in the process, preferentially evaporating impurity elements with saturated steam pressure higher than that of tellurium, condensing and dripping the impurity elements on the conical condenser into the vertical sampling detection tube, and detecting the content of main impurities of arsenic and selenium in a sample;

step four, when the content of the impurities arsenic and selenium in the sample is low, a secondary distillation process is carried out, the temperature of the vacuum distillation kettle, the conical condenser and the vertical sampling detection tube is adjusted, the temperature is kept for a set time, and the main impurities detected by the vertical sampling detection tube are the content of magnesium and sodium;

step five, when the content of impurities such as arsenic, selenium, magnesium and sodium in the sample is low, a three-stage distillation process is carried out, the temperature of a vacuum distillation kettle, a conical condenser and a vertical sampling detection tube is adjusted, the temperature is kept for a set time, the evaporation speed of tellurium is accelerated, impurities such as copper, lead, aluminum and silicon which are lower than the saturation vapor pressure of tellurium are enriched at the bottom of a graphite evaporation vessel, the vertical sampling detection tube product is detected, and the next step is started when the purity of tellurium reaches 6N;

step six, controlling the molten metal buffer kettle to a set temperature, opening a graphite valve between the distillation kettle and the molten metal buffer kettle, condensing tellurium vapor into liquid molten tellurium metal at the temperature, and staying in the molten metal buffer kettle;

controlling the hydrogen reduction furnace to a set temperature, opening a graphite valve between the hydrogen reduction furnace and the molten metal buffer kettle, enabling liquid molten tellurium metal to flow into the hydrogen reduction furnace, closing the graphite valve after a set amount is reached, opening a rotary air valve, introducing hydrogen to normal pressure, and stopping introducing the hydrogen after a set pressure is reached; cooling the tellurium, and taking out;

step eight, after the liquid molten tellurium in the hydrogen reduction furnace is cooled and taken out, starting a double-hole vacuum suction filter, carrying out vacuum-pumping treatment on the hydrogen reduction furnace, and waiting for next discharging of the molten metal buffer kettle; and after the completion of distillation is confirmed, cooling, opening the top cover of the vacuum distillation kettle, taking out residues for uniform storage, cleaning the equipment, collecting 6N high-purity tellurium, drying under an inert atmosphere, packaging and sealing.

Technical Field

The invention relates to a technology for preparing high-purity tellurium, in particular to equipment and a method for industrially preparing high-purity tellurium.

Background

Tellurium, having an atomic number of 52 in the periodic table, is located between selenium and polonium of main group VI of period 5, has more pronounced metallic properties than sulfur and selenium. With the continuous development of the current science and technology, the rapid progress of metallurgy, particularly the top-end science and technology fields such as the steel industry, military and the like, the purity requirement on tellurium is more and more strict, and the demand is more and more large. At present, methods for preparing high-purity tellurium include a zone melting method, a chemical method, a vacuum distillation method and the like, but the purity of tellurium is difficult to be improved to 6N by using the chemical method alone, and the method needs to be used together with a physical method. The method for purifying the tellurium metal by the zone melting method has the advantages of long period, more cycle times, high melting temperature and high energy consumption; the vacuum distillation method has simple operation, high production efficiency and small equipment investment, and is a method for efficiently preparing high-purity tellurium.

The larger the saturated vapor pressure value, the easier the evaporation. The vapor pressure of pure metals is only temperature dependent and conforms to the Clausius-Claebelon relationship:

in the formula, p is the vapor pressure of pure metal; t is the metal temperature; l is latent heat of metal evaporation; v_GIs the molar volume of the metal in the gaseous state; v_LIs the molar volume of the metal in the liquid state. Under the general conditions, V_LMuch less than V_GSo it is negligible, as defined by the ideal gas law:

V_G＝RT/p (4)

the saturated vapor pressure values of tellurium and each impurity metal at different temperatures were calculated by substituting the formula (4) for the integral in the formula (3). The calculation results of the saturated vapor pressures of the different metals at 500 ℃ and 550 ℃ are shown in the following tables 1 and 2:

TABLE 1500 saturated vapor pressure values of various metals

TABLE 2550 ℃ saturated vapor pressure values of different metals

As is clear from tables 1 and 2, the vapor pressure at which the impurity elements of Cu, Pb and Bi are saturated is much lower than that of Te, and therefore, they hardly volatilize during the distillation and remain in the liquid phase. Although the saturation vapor pressure of the impurity magnesium is smaller than that of tellurium, the saturation vapor pressure is relatively close, and part of magnesium enters a gas phase in the vacuum distillation process. The saturation vapor pressure of selenium, arsenic and sodium is higher than that of tellurium, and will exit into the gas phase in preference to tellurium during vacuum. When the temperature is increased from 500 ℃ to 550 ℃, the difference between the saturated vapor pressure of the impurity elements and the saturated vapor pressure of tellurium is obvious, the distillation temperature is continuously increased, the pressure difference value of the impurity elements and the saturated vapor is reduced, the separation of tellurium and impurities is not facilitated, and the purification effect of tellurium is influenced.

The Master thesis "research on vacuum distillation-zone melting purification of tellurium, Liu Si Qi" discloses a tower type vacuum distillation tellurium purification furnace, which can purify and prepare high-purity tellurium, but has the problems of low vacuum distillation efficiency, tellurium purity lower than 4N, easy pipeline blockage of distillation products and the like. CN201720015085.X discloses a vacuum distillation apparatus for refining high-purity metal, which is a one-stage distillation apparatus for preparing high-purity metal through purification, and has poor purification effect on metal raw materials with various impurity contents, and an inverted trapezoid raw material kettle is arranged at the bottom of the apparatus, so that the distillation efficiency is low, and the period is long. CN 201720594376.9 discloses a device for preparing high-purity crops by distillation and separation, which has good effect on gallium purification and high evaporation efficiency, but the device is designed according to the property of gallium and is not suitable for tellurium purification, and in addition, the device has poor controllability, and the temperature control accuracy without a cooling system is not high, and meanwhile, the evaporation condition inside the distillation device cannot be monitored.

CN201110439767.0 discloses a preparation device and a preparation method of high-purity selenium, the device can prepare 6N high-purity selenium, but the device adopts a traditional charging mode, and the distillation efficiency is low; the device is designed according to the property of selenium and is not suitable for separating impurities with saturated vapor pressure similar to that of metal tellurium, such as selenium and the like, and the tellurium purification effect is poor; the device adopts a traditional coil temperature controller, and the temperature control precision in the distillation process is low; the device has no observation hole, and the vacuum distillation process cannot be monitored; the device defective material discharge gate is not equipped with heating device, and the defective material easily cools off and blocks up the discharge gate, influences the distillation process and normally goes on. CN 201110456181.5 discloses a preparation equipment and a method of high-purity selenium, the device can prepare 5N high-purity zinc, the device has the problems of low distillation efficiency, low temperature control precision, incapability of monitoring the purity of a distillation product in real time and the like, and the method is designed according to the property of zinc and is not suitable for vacuum distillation of tellurium. CN 201821265882.4 discloses an apparatus for large-scale preparation of high-purity tellurium pills, which can realize batch preparation of high-purity tellurium pills, but the apparatus can only shape the tellurium material, and cannot realize efficient purification of tellurium, and has poor raw material adaptability.

Therefore, the prior high-purity tellurium or high-purity tellurium preparation device is still difficult to solve the problems of low distillation efficiency, poor distillation temperature control precision, poor impurity removal effect in metal tellurium, incapability of monitoring the distillation process in real time, long flow, high production cost, high energy consumption, low preparation efficiency and the like in industrial production of preparing high-purity tellurium in a large scale by vacuum distillation of tellurium.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects in the prior art and provide the equipment for preparing high-purity tellurium, which has high temperature control precision, high distillation purity and low energy consumption.

The invention further aims to solve the technical problem of providing a method for preparing high-purity tellurium by using the equipment for preparing high-purity tellurium.

The technical scheme adopted by the invention for solving the technical problems is as follows: the equipment for preparing high-purity tellurium comprises a vacuum distillation device, a vacuumizing device, a hydrogen purification circulating device, a high-frequency induction heating device and a product collecting device:

vacuum distillation device includes vacuum distillation cauldron, graphite evaporating dish more than two-layer, conical condenser, the funnel that gathers materials and vertical sampling test tube, conical condenser fixes vacuum distillation cauldron's inboard roof, the funnel that gathers materials is located conical condenser's below, graphite evaporating dish is located vacuum distillation cauldron's bottom, vertical sampling test tube runs through every graphite evaporating dish, vertical sampling test tube's upper end with the funnel that gathers materials is connected, and its lower extreme passes vacuum distillation cauldron's bottom and exposure in the outside, vacuum distillation cauldron's both sides wall is equipped with extraction opening and steam outlet respectively.

The vacuum pumping device is used for providing a vacuum environment and comprises a single-hole vacuum pumping filter and a double-hole vacuum pumping filter, wherein the single-hole vacuum pumping filter is connected with a pumping hole in the vacuum distillation kettle.

Preferably, a buffer tank is arranged between the vacuum suction filter and the vacuum distillation kettle.

The hydrogen purification circulating device is used for providing a hydrogen reduction environment for the collecting device.

The product collecting device comprises a molten metal buffer kettle and a hydrogen reducing furnace, wherein the molten metal buffer kettle is connected with the steam outlet and the hydrogen reducing furnace through a molten metal conveying pipe, a graphite valve is arranged on the molten metal conveying pipe, the molten metal buffer kettle is connected with a double-hole vacuum suction filter, and the hydrogen reducing furnace is respectively connected with the double-hole vacuum suction filter and a hydrogen purifying device;

the high-frequency induction heating devices are distributed on the two sides and the top end of the vacuum distillation kettle, the inner side of the vertical sampling detection pipe, the inner side of the molten metal buffer kettle and the inner side of the hydrogen reduction furnace.

Further, a transparent observation window is arranged on the vacuum distillation kettle.

Furthermore, the hydrogen purification device comprises a hydrogen purifier, a gas collection steel cylinder and a rotary gas valve.

Furthermore, the bottom of the vacuum distillation kettle is provided with a weight sensor which can monitor the weight of the multilayer graphite evaporation pan in real time.

Further, a graphite tower plate with a round hole in the middle is arranged in the vacuum distillation kettle, and the collecting funnel is fixed in the vacuum distillation kettle through the graphite tower plate.

The technical scheme adopted by the invention for further solving the technical problems is that the method for preparing high-purity tellurium by using the equipment for preparing high-purity tellurium comprises the following steps:

placing a crude tellurium raw material in a clean graphite evaporation vessel, recording display data of a weight sensor, and sequentially fixing and sealing a vertical sampling detection tube, a graphite tower plate, an aggregate funnel and a conical condenser;

at normal temperature and pressure, because the air pressure in the air is greater than the saturated vapor pressure of the molten metal in the furnace, tellurium and impurities in the crude tellurium are not easily volatilized in a gaseous state. Like the reaction at atmospheric pressure, the vacuum distillation process of tellurium also follows the laws of thermodynamics of materials.

According to the Gibbs law of thermodynamics free energy obtained by single phase transition reaction:

in the formula P_MTo a real partial pressure, P⁰At atmospheric pressure, a Gibbs free energy of less than zero, Δ G, is required for the vacuum distillation reaction to proceed smoothly_r<0, converted to obtain:

in the formula P_EFor the residual pressure in the vacuum distillation kettle, the formula shows that the residual pressure in the vacuum distillation kettle is necessarily smaller than the actual partial pressure of the metal, and the metal is volatilized into a gas phase from a molten state, so that the control of proper vacuum degree is crucial to the vacuum distillation process of tellurium;

step two, starting a single-hole vacuum suction filter and a double-hole vacuum suction filter for vacuum pumping treatment, wherein the vacuum distillation kettle, the molten metal buffer kettle, the hydrogen reduction furnace and the connected molten metal conveying pipe are all in a vacuum state, the vacuum pumping time is 4-8 hours, and the vacuum degree is controlled to be 10^-2～10^-5pa; the vacuum distillation of tellurium can be smoothly carried out under the vacuum degree condition;

step three, starting a high-frequency induction heating device, entering a primary distillation process, controlling the temperature of the interior of the vacuum distillation kettle, the conical condenser and the vertical sampling detection tube to be set temperature, keeping the temperature for set time, gradually melting the crude tellurium raw material in the process, preferentially evaporating impurity elements with saturated steam pressure higher than that of tellurium, condensing and dripping the impurity elements on the conical condenser into the vertical sampling detection tube, and detecting the content of main impurities such as arsenic, selenium and the like of a sample;

step four, when the arsenic and selenium content in the sample is low, a secondary distillation process is carried out, the temperature of the vacuum distillation kettle, the conical condenser and the vertical sampling detection tube is adjusted, the temperature is kept for a set time, and at the moment, the content of main impurities such as magnesium and sodium monitored by the vertical sampling detection tube is monitored;

step five, when the content of impurities such as arsenic, selenium, magnesium, sodium and the like in the sample is low, a three-stage distillation process is carried out, the temperature of a vacuum distillation kettle, a conical condenser and a vertical sampling detection tube is adjusted, the temperature is kept for a set time, the evaporation speed of tellurium is accelerated, impurities such as copper, lead, aluminum, silicon and the like which are lower than the saturation vapor pressure of tellurium are enriched at the bottom of a graphite evaporation vessel, the vertical sampling detection tube product is detected, and the next step is carried out when the purity of tellurium reaches 6N;

controlling the molten metal buffer kettle to a set temperature, opening a graphite valve between the vacuum distillation kettle and the molten metal buffer kettle, condensing tellurium vapor to liquid molten tellurium metal at the temperature, and staying in the molten metal buffer kettle;

controlling the hydrogen reduction furnace to a set temperature, opening a graphite valve between the hydrogen reduction furnace and the molten metal buffer kettle, enabling liquid molten tellurium metal to flow into the hydrogen reduction furnace, closing the graphite valve after a set amount is reached, opening a rotary gas valve to introduce hydrogen to normal pressure, and stopping introducing the hydrogen after a set pressure is reached; cooling the tellurium, and taking out;

step eight, after the liquid molten tellurium is cooled and taken out from the hydrogen reduction furnace, starting a double-hole vacuum suction filter, vacuumizing the double-hole vacuum suction filter, and waiting for next discharging of the molten metal buffer kettle; after the completion of distillation is confirmed, cooling, opening a top cover of the vacuum distillation kettle, taking out residues for uniform storage, and cleaning the equipment; drying the collected 6N high-purity tellurium in inert atmosphere, packaging and sealing.

Compared with the prior art, the invention has the advantages that:

1. the equipment for preparing high-purity tellurium has short flow and low energy consumption, omits the tellurium remelting process in the conventional process of preparing high-purity tellurium, and avoids the problems of high energy consumption in the remelting process and local oxidation caused by the charging process;

2. the vacuum distillation kettle of the equipment is provided with more than two layers of graphite evaporation vessels, so that the distillation efficiency can be greatly accelerated, and the preparation efficiency of high-purity tellurium can be improved; the preferred scheme is additionally provided with a transparent observation window, so that the distillation process can be observed at any time; a buffer tank is additionally arranged between the vacuum suction filter and the vacuum distillation kettle, so that the back suction is prevented, and part of tellurium residues can be collected in the process of multiple times of vacuum suction;

3. according to the equipment, a weight sensor is introduced in the preferred scheme, and the weight change trend of the crude tellurium raw material in the graphite evaporation vessel is monitored and recorded, so that the equipment can be used as a basis for controlling the temperature of each stage in the vacuum distillation process, and the impurity removal rate is improved; the equipment provided by the invention is provided with the vertical sampling detection tube, so that the purity of the high-purity tellurium product in the distillation process can be detected at any time, and the aim of flexibly regulating and controlling the vacuum distillation process is fulfilled.

4. The equipment is provided with the molten metal buffer kettle and is matched with the hydrogen reduction furnace, so that impurities such as selenium, arsenic and the like in high-purity tellurium can be efficiently removed in a hydrogen atmosphere, and the purity of the high-purity tellurium is improved; the equipment is provided with the hydrogen purifier, so that the hydrogen can be recycled, and the hydrogen resource is saved.

The method for preparing high-purity tellurium has short flow and low energy consumption, omits the high-purity tellurium remelting process in the conventional high-purity tellurium preparation process, and avoids the problems of high energy consumption in the remelting process and local oxidation caused by the charging process.

The method of the invention obtains the saturated vapor pressure data of each element through early calculation, strictly controls the distillation temperature, and implements sectional temperature control to separate tellurium from impurity elements such as selenium, arsenic, sodium, magnesium and the like in different temperature areas, thereby achieving the purpose of separation and purification. Based on the principle, a three-stage multi-section distillation process is designed, and meanwhile, a hydrogen reduction furnace is additionally arranged, so that selenium, arsenic and the like which are impurities which are close to tellurium saturated vapor pressure and difficult to remove and separate can be deeply removed in a hydrogenation deep reduction stage, impurity removal is further enhanced, and hydrogen recycling can be realized.

In conclusion, the invention has the advantages of high distillation efficiency, accurate temperature control, high controllability of the distillation process, low energy consumption, high hydrogen utilization rate, high tellurium purity, high impurity removal rate, low production cost and the like.

The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural view of an embodiment of the apparatus for producing high purity tellurium in accordance with the present invention;

FIG. 2 is a schematic view showing the internal structure of the vacuum distillation still of the embodiment shown in FIG. 1;

FIG. 3 is a top view of the graphite boat and vertical sampling and detection tube of the embodiment shown in FIG. 1.

Illustration of the drawings:

1. an air hose; 2. a buffer tank; 3. a vacuum distillation kettle; 4. a transparent viewing window; 5. a distillation header; 6. a graphite valve; 7. a molten metal delivery conduit; 8. a molten metal buffer kettle; 9. a double-hole vacuum suction filter; 10. a hydrogen purifier; 11. a hydrogen reduction furnace; 12. rotating the air valve; 18. a gas collection steel cylinder; 19. a vertical sampling detection tube; 20. a weight sensor; 21. a base; 22. a central controller; 23. a single-hole vacuum suction filter; 31. a heat insulation layer; 32. a spiral red copper coil; 33. an insulating protective layer; 34. a left side air extraction opening; 35. a cooling water pipe; 36. a conical condenser; 37. a right metal vapor outlet; 38. an aggregate funnel; 39. a graphite evaporating dish; 40. a hollow graphite tube; 41. graphite column plates; 42. and a secondary spiral hollow red copper coil.

Detailed Description

The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.

In this embodiment, the transparent observation windows 4 are uniformly distributed outside the vacuum distillation still 3 at fixed intervals, and the internal conditions of the vacuum distillation still 5 can be observed from a plurality of angles. Be equipped with buffer tank 2 between vacuum distillation cauldron 3 and the haplopore vacuum suction filter 23, the left extraction opening 34 of vacuum distillation cauldron 3 links to each other with buffer tank 2, is equipped with graphite valve 6 on the pipeline that left side extraction opening 34 and buffer tank 2 are connected, can close graphite valve 6 after the evacuation step is accomplished, isolates vacuum distillation cauldron 3 and buffer tank 2 and comes. Molten metal conveying pipeline 7 links to each other with right side metal steam outlet 37 and molten metal buffering cauldron 8, and molten metal buffering cauldron 8 and molten metal conveying pipeline 7 skin parcel spiral red copper coil 32 and condenser tube 35 are favorable to realizing accurate accuse temperature, but utilize graphite valve 6 accurate control feeding and ejection of compact. The molten metal buffer kettle 8 is connected with the hydrogen reducing furnace 11 through a molten metal conveying pipe 7, a graphite valve 6 is arranged in the middle, and the discharging of the molten metal buffer kettle 8 can be freely controlled. The right side of the molten metal buffer kettle 8 is connected with a double-hole vacuum suction filter 9 which can vacuumize the inside of the molten metal buffer kettle 8. Two ends of the hydrogen reducing furnace 11 are respectively connected with a double-hole vacuum pumping filter 9 and a hydrogen purification circulating device, and the hydrogen purification device comprises a hydrogen purifier 10, a gas collection steel cylinder 18 and a rotary gas valve 12. The double-hole vacuum pumping filter 9 provides a vacuum environment for the hydrogen reduction furnace 11 before hydrogen is introduced, the gas collection steel cylinder 18 is used for storing hydrogen, the interface is provided with the rotary gas valve 12, the flow rate of the hydrogen introduced into the hydrogen reduction furnace can be accurately controlled, an inert environment is provided for the hydrogen reduction furnace 11, the hydrogen purifier 10 can purify the hydrogen, the pollution of impurities such as carbon, nitrogen, oxygen, hydrogen selenide and the like in the hydrogen is removed, and the hydrogen is recycled.

In this embodiment, the top of the vacuum distillation still 3 is provided with a distillation top cover 5 which can be freely detached. The inner side of the vacuum distillation still 3 is provided with a heat insulation layer 31. And a cooling water pipe 35 is arranged adjacent to the heat insulation layer 31, cooling water can be introduced to cool the interior of the vacuum distillation kettle 3, and the cooling water pipe 35 is coated on the periphery of the spiral red copper coil 32. A high-temperature resistant insulating protective layer 33 is arranged between the inner wall of the vacuum distillation kettle 3 and the spiral red copper coil 32. The conical condenser 36 at the top of the vacuum still 3 performs the condensation function. The graphite tower plate 41 is used for fixing the collecting funnel 38, a round hole is arranged in the middle of the graphite tower plate 41, and the collecting funnel 38 is clamped in the middle of the graphite tower plate 41. The vertical sampling detection tube 19 is connected with the aggregate funnel 38, the periphery of the vertical sampling detection tube 19 is provided with a heat insulation layer, the inside of the vertical sampling detection tube 19 is provided with a secondary spiral hollow red copper coil 42, and the secondary spiral hollow red copper coil 42 can be introduced with cooling water for accurate temperature control. The secondary spiral hollow red copper coil 42 is covered with an insulating protective layer to protect the inner wall of the vertical sampling detection tube 19.

In this embodiment, independently controlled high frequency induction heating devices are provided on both sides and the top of the vacuum distillation still 3, an independently controlled high frequency induction heating device is provided on the vertical sampling detection pipe 19, an independently controlled high frequency induction heating device is provided on the molten metal buffer vessel 8 and the molten metal delivery pipe 7 connected thereto, and an independently controlled high frequency induction heating device is also provided on the hydrogenation reduction furnace 11 and the molten metal delivery pipe 7 connected thereto. The high-frequency induction heating apparatuses are integrally controlled and displayed on the central controller 22. The weight sensor 20 is shown in integrated control on a central controller 22 with readings accurate to decimals. The parts directly contacting with the molten metal such as the graphite evaporating dish 39, the hydrogen reducing furnace 11, the molten metal delivery pipe 7, the molten metal buffer vessel 8 and the like are all made of 5N high-purity graphite so as to prevent impurities such as silicon and the like from being brought into the quartz tube in the long-time melting and retaining process of the high-purity tellurium.

The method for preparing high-purity tellurium by using the equipment for preparing high-purity tellurium comprises the following steps:

placing a crude tellurium raw material into a clean multilayer graphite evaporation vessel 39, recording display data of a weight sensor 20, and sequentially fixing and sealing a vertical sampling detection tube 19, a graphite tower plate 41, an aggregate funnel 38, a condenser 35 and a distillation top cover 36; recording the weight of the multilayer graphite evaporating dish 39, placing the multilayer graphite evaporating dish on the weight sensor 20, and after peeling, displaying that the weight is 0 by the central controller 22 of the weight sensor 20; taking a crude tellurium raw material by using a clean titanium spoon, uniformly placing the crude tellurium raw material in a multilayer graphite evaporating dish 39, recording the weight of the tellurium raw material, and setting the number of layers of the graphite evaporating dish 39 to be 2-10 layers according to actual requirements; the multi-layer graphite evaporation pan 39 is placed at the bottom of the vacuum distillation kettle 3, the vertical sampling detection tube 19 is fixed at the center of the graphite evaporation pan 39, the graphite tower plate 41 is fixed in the middle of the vacuum distillation kettle 3, the collecting funnel 38 is clamped in the middle of the graphite tower plate 41 and is connected with the vertical sampling detection tube 19 in an inscribed mode, the distillation top cover 5 is covered after the conical condenser 36 is installed, and sealing treatment is carried out.

Step two, starting the single-hole vacuum suction filter 23 and the double-hole vacuum suction filter 9 for vacuum treatment, wherein the vacuum distillation kettle 3, the molten metal buffer kettle 8, the hydrogen reduction furnace 11 and all connected molten metal conveying pipes are in a vacuum state, the vacuum-pumping time is 4-8 hours, and the vacuum degree is controlled at 10^-2～10^-5pa, the vacuum distillation of tellurium can be smoothly carried out under the vacuum degree condition;

step three, starting a high-frequency induction heating device, and entering a primary distillation process; controlling the internal temperature of the vacuum distillation kettle 3 to be 495-505 ℃, wherein the crude tellurium raw material is at a melting state critical point at the temperature, if the melting effect of the crude tellurium raw material is poor below the temperature, the tellurium evaporation rate in the temperature interval is 2.3-5.8%, if the melting effect of the crude tellurium raw material is higher than the temperature, the tellurium evaporation rate is greatly increased, and evaporated tellurium is mixed with impurities such as arsenic, selenium and the like, so that the yield of high-purity tellurium is reduced preferentially; controlling the temperature of the conical condenser 36 and the vertical sampling detection pipe 19 to be 250-280 ℃, condensing arsenic and selenium steam when meeting cold at the temperature, and flowing into the aggregate funnel 38 along the outer wall of the conical condenser 36 so as to enter the vertical sampling detection pipe 19; the duration time of the first-stage distillation process is 1-6 hours, and when the content of impurities such as arsenic, selenium and the like in the sample in the vertical sampling detection tube 19 is low, the next-stage distillation process is carried out;

step four, when the arsenic and selenium content in the sample is low, a secondary distillation process is carried out, the temperature of the vacuum distillation kettle 3, the conical condenser 36 and the vertical sampling detection pipe 19 is adjusted, the temperature is kept for a set time, and the content of main impurities such as magnesium and sodium is detected for the sample; controlling the internal temperature of a distillation kettle 3 to be 510-520 ℃, slightly accelerating the distillation rate of a tellurium raw material at the temperature, wherein the evaporation rate of tellurium in the temperature interval is 6.4-10.2%, if the temperature is lower than the temperature, impurities with saturated vapor pressure similar to that of tellurium, such as magnesium, sodium and the like are difficult to separate, if the temperature is higher than the temperature, the increase amplitude of the evaporation rate of tellurium is large, and the evaporated tellurium is mixed with impurities such as magnesium, sodium and the like, so that the yield of high-purity tellurium is reduced preferentially; controlling the temperature of the conical condenser 36 and the vertical sampling detection tube 19 to be 260-300 ℃, and enabling magnesium and sodium vapor to flow into the aggregate funnel 38 along the outer wall of the conical condenser 36 to enter the vertical sampling detection tube 19 after precooling and condensing; the duration time of the secondary distillation process is 1-4 hours, and the next-stage distillation process is carried out when the content of impurities such as magnesium, sodium and the like in the sample in the vertical sampling detection tube 19 is low;

step five, when the content of impurities such as arsenic, selenium, magnesium, sodium and the like in a sample is low, a three-stage distillation process is carried out, the internal temperature of the vacuum distillation kettle 3 is controlled to be 525-540 ℃, the distillation rate of the tellurium raw material is greatly accelerated at the temperature, the evaporation rate of tellurium in the temperature interval is high, if the temperature is lower than the temperature, the distillation rate of tellurium is lower, and if the temperature is higher than the temperature, although the increase range of the evaporation rate of tellurium is large, part of impurity elements such as lead, bismuth and the like in the tellurium raw material are evaporated together and mixed with tellurium, so that the yield of high-purity tellurium is reduced; controlling the temperature of the conical condenser 36 and the temperature of the vertical sampling detection tube to be 270-280 ℃, enabling tellurium steam to pre-cool and condense along the outer wall of the conical condenser 36 and flow into the aggregate funnel 38 to enter the vertical sampling detection tube 19 at the temperature, detecting the purity of a sample, adjusting the temperature of the conical condenser 36 and the temperature of the vertical sampling detection tube 19 to be 525-540 ℃ when the purity of the tellurium sample reaches 6N, and if the temperature is lower than the temperature, the tellurium steam is easy to condense and enters the vertical sampling detection tube 19 to block the subsequent high-purity tellurium preparation process, wherein the duration time of the three-stage distillation process is 4-20 hours.

Sixthly, controlling the temperature of the molten metal buffer kettle 8 to be 450-460 ℃, and condensing tellurium steam into molten liquid metal at the temperature; opening a graphite valve 6 between the vacuum distillation kettle 3 and the molten metal buffer kettle 8, storing molten liquid tellurium metal in the molten metal buffer kettle 8, starting discharging when the charge of the molten metal buffer kettle 8 accounts for more than 1/2-2/3 of the kettle internal volume, and easily generating the risk of flash when the charge is higher than the amount;

seventhly, controlling the temperature of the hydrogen reduction furnace 11 to 450-460 ℃, opening a graphite valve 6 between the hydrogen reduction furnace 11 and the molten metal buffer kettle 8, enabling the liquid molten tellurium metal to flow into the hydrogen reduction furnace 11, and closing the graphite valve 6 when the liquid molten tellurium metal reaches the hearth inner volume of 1/2-2/3; opening a rotary air valve 12, introducing hydrogen to normal pressure, wherein the purity of the hydrogen is 6N, the flow rate of the introduced hydrogen is 4.5-6.0L/min, and after deep reduction treatment of the hydrogen for 1-6 hours, stopping introducing the hydrogen; after the reduction is finished, taking out the tellurium after the tellurium is cooled;

step eight, after the liquid molten tellurium in the hydrogen reduction furnace 11 is cooled and taken out, sealing the hydrogen reduction furnace 11, starting the double-hole vacuum suction filter 9, vacuumizing the double-hole vacuum suction filter for 2-8 hours, and controlling the vacuum degree to be 10^-3～10^{- 4}pa, waiting for next discharging of the molten metal buffer kettle 8; when the data of the weight sensor 20 is almost unchanged, the temperature is reduced and the distillation is confirmed to be finished by observing from the transparent observation window 4, the distillation top cover 5 is opened, the residues are taken out and stored uniformly, the content of impurities such as copper, lead, aluminum, bismuth and the like in the residues is high, the residues can be further recycled and treated, the equipment is cleaned, 6N high-purity tellurium is collected and dried in an inert atmosphere environment, and then the dried residues are packaged and sealed by plastic.