A regional melting furnace and a method for preparing 7N high-purity tellurium

Abstract

The present invention provides a zone melting furnace and a method for preparing 7N high-purity tellurium, comprising: a zone melting boat unit, a transmission and heating unit, a temperature control unit and a vacuum unit; wherein the zone melting boat unit is composed of a plurality of annular zone melting boats, the transmission and heating unit comprises a transmission mechanism and a heating mechanism, the transmission mechanism is composed of a plurality of force transmission rods and a transmission shaft, and the heating mechanism is composed of a plurality of semicircular resistance coils; one end of the force transmission rod is fixed on the transmission shaft; the other end is connected to the semicircular resistance coil, and the semicircular resistance coil is located below the bottom of the annular zone melting boat; the present invention uses the design of the transmission and heating unit in conjunction with the zone melting boat unit, and when the zone melting boat is stationary, the transmission shaft is used to drive the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a unidirectional circular motion along the bottom of the annular zone melting boat, so as to continuously zone melt the material in the annular zone melting boat; compared with traditional zone melting equipment, it saves more space, and multi-layer and multi-melting zone zone melting can greatly improve the melting output.

Description

Technical Field

[0001] The present invention relates to the technical field of zone smelting, and in particular to a zone smelting furnace and a method for preparing 7N high-purity tellurium. Background Art

[0002] Tellurium metal is an important strategic rare metal, which is widely used in modern industry and national defense construction, and is known as the "vitamin of modern industry, national defense and cutting-edge technology". With the continuous development of society and the continuous advancement of science and technology, the purity requirements of tellurium metal are getting higher and higher. The purity of high-purity tellurium materials is an important factor that directly affects the performance of materials.

[0003] 7N high-purity tellurium is mainly used in the preparation of cadmium telluride solar thin-film battery materials. The purification methods of 7N high-purity tellurium mainly include electron beam melting, zone melting and other technologies. Among them, the zone melting equipment plays a key role in the purification of metallic tellurium. It has many advantages such as good purification effect and high impurity removal content. It is of great significance to the development of industrial production of high-purity metals. The principle is that there is a difference in the solubility of impurity elements in the solidified and molten states of tellurium, which changes the precipitation and distribution of impurity elements in tellurium, thereby realizing the separation of impurities and tellurium. Zone melting is a common purification method for preparing ultra-high purity materials. However, the existing zone melting furnaces have the problems of slow purification efficiency and low recovery rate, which need to be improved. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides a regional melting furnace and a method for preparing 7N high-purity tellurium, which greatly improves the purification efficiency and output.

[0005] The specific content of the invention is as follows:

[0006] In a first aspect, the present invention provides a zone melting furnace, comprising: a zone melting boat unit, a transmission heating unit, a temperature control unit and a vacuum unit; wherein:

[0007] The zone melting boat unit is composed of a plurality of annular zone melting boats, and the annular zone melting boats are vertically distributed in the furnace body from top to bottom;

[0008] The transmission heating unit includes a transmission mechanism and a heating mechanism, wherein the transmission mechanism is composed of a plurality of force transmission rods and a transmission shaft, and the heating mechanism is composed of a plurality of semicircular resistance coils; the transmission shaft is located on the axis where the centers of the plurality of annular zone melting boats are located; one end of the force transmission rod is fixed to the transmission shaft; the other end is connected to the semicircular resistance coil, and the semicircular resistance coil is located below the bottom of the annular zone melting boat, and the transmission shaft drives the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a circular motion along the bottom of the annular zone melting boat, so as to continuously zone melt the material in the annular zone melting boat; each of the annular zone melting boats corresponds to no less than one semicircular resistance coil;

[0009] The temperature control unit is composed of a plurality of thermocouples, which are located at the bottom of the semicircular resistance coil and are used for temperature control and temperature measurement;

[0010] The vacuum unit is provided with a vacuum pump for adjusting the vacuum degree in the zone smelting furnace.

[0011] Optionally, the number of the semicircular resistance coils and the force transmission rods corresponding to each of the annular zone melting boats is the same.

[0012] Optionally, when each of the annular zone melt boats is provided with no less than one of the semicircular resistance coils, a plurality of the semicircular resistance coils are evenly distributed below the bottom of the annular zone melt boat at the same intervals.

[0013] Optionally, each of the annular zone melt boats is fixed to the furnace wall by a lock.

[0014] Optionally, the transmission heating unit further includes a driving power supply, which provides power for the transmission shaft.

[0015] Optionally, a detachable furnace cover is provided on the top of the furnace body of the zone smelting furnace to facilitate taking out the annular zone melting boat.

[0016] Optionally, the removable furnace cover is provided with a glass window for observing the smelting process of the material.

[0017] Optionally, the annular zone melting boat is made of high-purity quartz or high-purity graphite material.

[0018] In a second aspect, the present invention provides a method for preparing 7N high-purity tellurium, wherein the 7N high-purity tellurium is prepared using the zone melting furnace described in the first aspect, comprising:

[0019] Laying the 6N tellurium raw material flat in a plurality of annular zone melting boats, and fixing the annular zone melting boats vertically to the furnace wall from bottom to top using locking buckles;

[0020] Turn on the vacuum unit to evacuate the regional smelting furnace to make the vacuum degree in the furnace 0.001Pa-20Pa;

[0021] Turn on the transmission heating unit to make the semicircular resistance coil move in a circle along the bottom of the annular zone melting boat to perform continuous zone melting on the 6N tellurium raw material in the annular zone melting boat; the temperature of the continuous zone melting is 500-800°C, the rate is 0.5-5mm / min, the number of times is 10-30 times, and the width is 5-10cm;

[0022] After the zone melting work is completed, the transmission heating unit is turned off, and the temperature in the furnace is reduced to room temperature. The vacuum unit is turned off, the annular zone melting boat is taken out, and 15 cm at both ends of the annular zone melting boat is removed. After the middle part is demolded, 7N high-purity tellurium is obtained.

[0023] Optionally, the temperature of the continuous zone melting is 650-750°C, the speed is 2-5 mm / min, the number of times is 10-20 times, and the width is 8-10 cm;

[0024] The vacuum degree in the furnace is 1Pa-10Pa.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The present invention provides a zone melting furnace, comprising: a zone melting boat unit, a transmission heating unit, a temperature control unit and a vacuum unit; wherein the zone melting boat unit is composed of a plurality of annular zone melting boats, which are vertically distributed in the furnace body from top to bottom; the transmission heating unit includes a transmission mechanism and a heating mechanism, the transmission mechanism is composed of a plurality of force transmission rods and a transmission shaft, and the heating mechanism is composed of a plurality of semicircular resistance coils; the transmission shaft is located on the axis where the centers of the plurality of annular zone melting boats are located; one end of the force transmission rod is fixed to the transmission shaft; the other end is connected to the semicircular resistance coil, the semicircular resistance coil is located below the bottom of the annular zone melting boat, the transmission shaft drives the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a circular motion along the bottom of the annular zone melting boat, so as to continuously zone melt the material in the annular zone melting boat; each of the annular zone melting boats corresponds to at least one semicircular resistance coil; the temperature control unit is composed of a plurality of thermocouples, the thermocouple is located at the bottom of the semicircular resistance coil, and is used for temperature control and temperature measurement.

[0027] The zone melting furnace provided by the present invention realizes multi-layer relay resistance heating by means of the design of the transmission heating unit and the annular zone melting boat, and simultaneously performs continuous zone melting on the materials in multiple annular zone melting boats. Compared with the traditional zone melting equipment, it saves more space, and the multi-layer and multi-melting zone regional melting greatly improves the melting output. In addition, the design of the semicircular resistance coil makes the loading and unloading process of the annular zone melting boat more convenient, and the work efficiency is greatly improved.

[0028] The zone melting furnace provided by the present invention, when the zone melting boat is stationary, utilizes the transmission shaft to drive the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a unidirectional circular motion along the bottom of the annular zone melting boat until the zone melting work is completed. Compared with traditional zone melting equipment, it saves time and improves melting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A schematic diagram of the structure of a zone smelting furnace provided in an embodiment of the present invention is shown;

[0031] Figure 2 A top view of the structure of a zone smelting furnace provided by an embodiment of the present invention is shown;

[0032] Figure 3 A flow chart of a method for preparing 7N high-purity tellurium provided in an embodiment of the present invention is shown.

[0033] Description of reference numerals:

[0034] 1-furnace body; 2-annular zone melting boat; 3-semicircular resistance coil; 4-lock; 5-transmission shaft; 6-vacuum pump; 7-driving power supply; 8-glass window; 9-thermocouple; 10-force transmission rod. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work belong to the scope of protection of the present invention.

[0036] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0037] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0038] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0039] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The following is a detailed description of the zone melting furnace provided in the embodiment of the present application in conjunction with the accompanying drawings:

[0041] The purpose of the present invention is to provide a zone melting furnace, comprising: a zone melting boat unit, a transmission heating unit, a temperature control unit and a vacuum unit; Figure 1 The schematic diagram of the structure of the zone smelting furnace provided by the embodiment of the present invention is shown as follows: Figure 1 As shown, the zone melt boat unit is composed of a plurality of annular zone melt boats 2, and the annular zone melt boats 2 are made of high-purity quartz or high-purity graphite material; the annular zone melt boats 2 are distributed in the furnace body 1 from bottom to top at a certain interval, and the centers of the plurality of annular zone melt boats 2 coincide in the vertical direction; the multi-layer structure zone melt boat unit formed by the plurality of annular zone melt boats 2 effectively increases the output and efficiency of zone smelting, and the zone melt boats arranged in multiple layers in the vertical direction have the advantages of small footprint and low energy consumption.

[0042] The transmission heating unit comprises a transmission mechanism and a heating mechanism, wherein the transmission mechanism is composed of a plurality of force transmission rods 10 and a transmission shaft 5, and the heating mechanism is composed of a plurality of semicircular resistance coils 3; Figure 2 FIG. 4 shows a top view of the structure of the zone smelting furnace provided by an embodiment of the present invention. Figure 2 As shown, the transmission shaft 5 is located on the axis where the centers of the multiple annular zone melt boats 2 are located; one end of the force transmission rod 10 is fixed on the transmission shaft 5; the other end is connected to the semicircular resistance coil 3; the semicircular resistance coil 3 is located below the bottom of the annular zone melt boat 2.

[0043] It should be noted that the number of force transmission rods 10 matches the number of semicircular resistance coils 3, and the number of semicircular resistance coils 3 is in a multiple relationship with the number of annular zone melt boats 2; in specific implementation, the number of semicircular resistance coils 3 can be determined based on the number of annular zone melt boats 2, thereby determining the number of semicircular resistance coils 3; each annular zone melt boat 2 corresponds to no less than one semicircular resistance coil 3.

[0044] It should also be noted that the annular zone melt boat 2 is not in contact with the semicircular resistance coil 3. In the vertical direction, the semicircular resistance coil 3 is set at a certain distance from the bottom of the annular zone melt boat 2. The semicircular resistance coil 3 is connected to the force transmission rod, and the force transmission rod is fixed on the transmission shaft 5 to fix and support the semicircular resistance coil 3. The rotation of the transmission shaft 5 drives the force transmission rod 10 to rotate, thereby driving the semicircular resistance coil 3 to make a circular motion along the bottom of the annular zone melt boat 2. With the help of the continuous movement of the resistance coil, continuous zone melting of the material in the annular zone melt boat 2 is achieved.

[0045] The temperature control unit is specifically composed of a plurality of thermocouples 9, see Figure 1 The thermocouple 9 is located at the bottom of the semicircular resistance coil 3 and is in contact with the semicircular resistance coil 3 for temperature control and temperature measurement. A thermocouple 9 is provided at the bottom of each semicircular resistance coil 3 to increase the accuracy of temperature control and temperature measurement.

[0046] The vacuum unit is provided with a vacuum pump 6, which can adjust the vacuum degree in the regional melting furnace as required.

[0047] In some embodiments, when each annular zone melting boat is provided with at least one semicircular resistance coil, a plurality of semicircular resistance coils are evenly distributed below the bottom of the annular zone melting boat at the same intervals. Figure 1 , Figure 2 In the zone melting furnace shown, the zone melting boat unit consists of three annular zone melting boats 2 distributed in the furnace body 1 at a certain interval; the transmission shaft is located on the axis where the centers of the three annular zone melting boats are located, and each annular zone melting boat is correspondingly provided with three semicircular resistance coils 3, and the three semicircular resistance coils 3 are evenly distributed below the bottom of the annular zone melting boat with the same interval, and the semicircular resistance coils are fixed to one end of a force transmission rod, and the other end of the force transmission rod is fixed to a transmission shaft 5. With the support of the force transmission rod 10 by the transmission shaft 5, the semicircular resistance coils 3 are fixed and supported; the force transmission rod 10 connected thereto is driven to rotate by the rotation of the transmission shaft 5, thereby driving the semicircular resistance coils 3 to make a circular motion along the bottom of the annular zone melting boat 2. Since each annular zone melting boat is correspondingly provided with three semicircular resistance coils 3, the material in the annular zone melting boat 2 is heated more evenly, and during the zone melting process, the annular zone melting boat 2 always remains motionless, and the material in the annular zone melting boat 2 is continuously zone melted by the movement of the semicircular resistance coils, and the zone melting efficiency is greatly increased.

[0048] In some embodiments, the annular zone melt boat 2 is fixed to the furnace wall of the zone melting furnace by a lock 4. When loading materials, the lock is opened and the annular zone melt boats 2 fixed to the furnace wall are taken out one by one. After the material filling is completed, the annular zone melt boat 2 filled with materials is placed into the zone melting furnace and fixed to the furnace wall in layers from bottom to top by connecting the lock 4. Since the transmission heating unit does not contact the annular zone melt boat 2 and the design of the semicircular resistance coil 2 makes the loading and unloading process of the annular zone melt boat more convenient, and the work efficiency is greatly improved.

[0049] In some embodiments, the transmission heating unit also includes a driving power supply 7, which serves as a power device of the transmission heating unit to provide power for the transmission shaft 5 to drive the force transmission rod 10 to rotate, thereby driving the semicircular resistance coil 3 to make a circular motion along the bottom of the annular zone melting boat 2.

[0050] In some embodiments, the zone smelting furnace is further provided with a detachable furnace cover to facilitate the removal of the annular zone melting boat. Further, a glass window 8 is provided on the furnace cover to facilitate observation of the smelting process of the material.

[0051] Another object of the present invention is to provide a method for preparing 7N high-purity tellurium, wherein the 7N high-purity tellurium is prepared by using the zone melting furnace described in the first aspect. Figure 3 The flowchart of the method for preparing 7N high purity tellurium provided in the embodiment of the present invention is shown as follows: Figure 3 As shown, including:

[0052] S1. Spread 6N tellurium raw material flat in a plurality of annular zone melting boats, and fix the annular zone melting boats vertically to the furnace wall from bottom to top using lock buckles;

[0053] S2, start the vacuum unit to vacuum the regional melting furnace to make the vacuum degree in the furnace 0.001Pa-20Pa;

[0054] S3, turning on the transmission heating unit to make the semicircular resistance coil move in a circular motion along the bottom of the annular zone melting boat, so as to continuously zone melt the 6N tellurium raw material in the annular zone melting boat;

[0055] S4. After the zone melting work is completed, turn off the transmission heating unit, wait until the temperature in the furnace drops to room temperature, turn off the vacuum unit, take out the annular zone melting boat, remove 15 cm from both ends of the annular zone melting boat, demold the middle part, and obtain 7N high-purity tellurium.

[0056] In specific implementation, the material of the annular zone melting boat is made of high-purity quartz or high-purity graphite material; the transmission shaft in the transmission heating unit is rotated to drive the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a circular motion along the bottom of the annular zone melting boat, so that the 6N tellurium raw material in the annular zone melting boat is heated by resistance, and continuous zone melting occurs; the zone melting temperature is monitored and controlled in real time by a temperature control unit (thermocouple); for the preparation of 7N high-purity tellurium, the zone melting temperature is between 500-800°C; the zone melting rate and the number of zone melting times are controlled by a driving power supply, and the zone melting rate is between 0.5-5mm / min; the number of zone melting times is between 10-30 times; and the zone melting width is between 5-10cm.

[0057] As a preferred result, the zone melting temperature is between 650-750°C; the zone melting rate is between 2-5 mm / min; the number of zone melting is between 10-20 times; the zone melting width is between 8-10 cm; and the vacuum degree in the furnace is between 1 Pa-10 Pa.

[0058] In order to enable those skilled in the art to more clearly understand the present invention, a zone melting furnace and a method for preparing 7N high-purity tellurium according to the present invention are now described in detail through the following examples.

[0059] The following examples are Figure 1 , Figure 2 The zone melting furnace shown is used to prepare 7N high purity tellurium.

[0060] Embodiment 1:

[0061] Spread the 6N tellurium raw material flat in the clean annular zone melting boat 2, connect the annular zone melting boat 2 to the furnace body 1 from bottom to top using the lock 4, and close the furnace cover. Turn on the vacuum pump 6 to evacuate the vacuum to 10 -1 pa, turn on the driving power supply 7, use the driving power supply 7 to drive the transmission shaft 5, the rotation of the transmission shaft 5 drives the force transmission rod 10 connected to it to rotate, thereby driving the semicircular resistance coil 3 to make a circular motion along the bottom of the annular zone melting boat 2, and the annular zone melting boat 2 is heated to 550℃ by the semicircular resistance coil 3, and the material is continuously zone melted to form multiple zone melting intervals. Set the zone melting rate to 0.5mm / min; the number of zone melting is 30 times; the zone melting width is 5cm. After the zone melting work is completed, turn off the driving power supply 7 first, wait until the temperature reaches room temperature, turn off the vacuum pump 6, open the furnace cover, take out the upper, middle and lower three layers of the annular zone melting boat 2, remove 15cm at both ends of the annular zone melting boat 2, and demold the middle part, which is 7N high-purity tellurium, and then collect it.

[0062] Embodiment 2:

[0063] Spread the 6N tellurium raw material flat in the clean annular zone melting boat 2, connect the annular zone melting boat 2 to the furnace body 1 from bottom to top in sequence with the lock 4, and close the furnace cover. Turn on the vacuum pump 6 to evacuate to 1pa, turn on the driving power supply 7, use the driving power supply 7 to drive the transmission shaft 5, and the rotation of the transmission shaft 5 drives the force transmission rod 10 connected to it to rotate, thereby driving the semicircular resistance coil 3 to make a circular movement along the bottom of the annular zone melting boat 2, and the annular zone melting boat 2 is heated to 650℃ by the semicircular resistance coil 3, and the material is continuously zone melted to form multiple zone melting intervals. Set the zone melting rate to 2mm / min; the number of zone melting is 20 times; the zone melting width is 8cm. After the zone melting work is completed, turn off the driving power supply 7 first, turn off the vacuum pump 6 when the temperature reaches room temperature, open the furnace cover, take out the upper, middle and lower three layers of the annular zone melting boat 2, remove 15cm at both ends of the annular zone melting boat 2, and demold the middle part to obtain 7N high-purity tellurium for collection.

[0064] Embodiment 3:

[0065] Spread the 6N tellurium raw material flat in the clean annular zone melting boat 2, connect the annular zone melting boat 2 to the furnace body 1 from bottom to top in sequence with the lock 4, and close the furnace cover. Turn on the vacuum pump 6 to evacuate to 10pa, turn on the driving power supply 7, use the driving power supply 7 to drive the transmission shaft 5, and the rotation of the transmission shaft 5 drives the force transmission rod 10 connected to it to rotate, thereby driving the semicircular resistance coil 3 to make a circular movement along the bottom of the annular zone melting boat 2, and the annular zone melting boat 2 is heated to 750℃ by the semicircular resistance coil 3, and the material is continuously zone melted to form multiple zone melting intervals. Set the zone melting rate to 5mm / min; the number of zone melting is 10 times; the zone melting width is 10cm. After the zone melting work is completed, turn off the driving power supply 7 first, turn off the vacuum pump 6 when the temperature reaches room temperature, open the furnace cover, take out the upper, middle and lower three layers of the annular zone melting boat 2, remove 15cm from both ends of the annular zone melting boat 2, and demold the middle part to obtain 7N high-purity tellurium for collection.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0067] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0068] The above is a detailed introduction to a zone melting furnace and a method for preparing 7N high-purity tellurium provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A zone smelting furnace, characterized in that: include: Zone melting boat unit, transmission heating unit, temperature control unit and vacuum unit; among them, The zone melt boat unit is composed of a plurality of annular zone melt boats, which are vertically distributed in the furnace body from top to bottom, and each of the annular zone melt boats is fixed to the furnace wall by a lock; The transmission heating unit includes a transmission mechanism and a heating mechanism, wherein the transmission mechanism is composed of a plurality of force transmission rods and a transmission shaft, and the heating mechanism is composed of a plurality of semicircular resistance coils; the transmission shaft is located on the axis where the centers of the plurality of annular zone melting boats are located; one end of the force transmission rod is fixed to the transmission shaft; the other end is connected to the semicircular resistance coil, and the semicircular resistance coil is located below the bottom of the annular zone melting boat, and the transmission shaft drives the force transmission rod to rotate, thereby driving the semicircular resistance coil to make a circular motion along the bottom of the annular zone melting boat, so as to continuously zone melt the material in the annular zone melting boat; each of the annular zone melting boats corresponds to no less than one semicircular resistance coil; The temperature control unit is composed of a plurality of thermocouples, which are located at the bottom of the semicircular resistance coil and are used for temperature control and temperature measurement; The vacuum unit is provided with a vacuum pump for adjusting the vacuum degree in the zone smelting furnace.

2. The zone smelting furnace according to claim 1, characterized in that: The number of the semicircular resistance coils and the force transmission rods corresponding to each of the annular zone melting boats is the same.

3. The zone smelting furnace according to claim 2, characterized in that: When each of the annular zone melting boats is provided with no less than one semicircular resistance coil, a plurality of the semicircular resistance coils are evenly distributed below the bottom of the annular zone melting boat at the same intervals.

4. The zone smelting furnace according to claim 1, characterized in that: The transmission heating unit also includes a driving power supply, which provides power for the transmission shaft.

5. The zone smelting furnace according to claim 1, characterized in that: A detachable furnace cover is arranged on the furnace body wall of the zone smelting furnace to facilitate taking out the annular zone melting boat.

6. The zone smelting furnace according to claim 5, characterized in that: The detachable furnace cover is provided with a glass window for observing the smelting process of the material.

7. The zone smelting furnace according to claim 1, characterized in that: The annular zone melting boat is made of high-purity quartz or high-purity graphite material.

8. A method for preparing 7N high-purity tellurium, characterized in that: The 7N high-purity tellurium is prepared by using the zone melting furnace described in any one of claims 1 to 7, comprising: Laying the 6N tellurium raw material flat in a plurality of annular zone melting boats, and fixing the annular zone melting boats vertically to the furnace wall from bottom to top using locking buckles; Turn on the vacuum unit to evacuate the regional smelting furnace to a vacuum degree of 0.001 Pa-20 Pa; Turn on the transmission heating unit to make the semicircular resistance coil move in a circle along the bottom of the annular zone melting boat to perform continuous zone melting on the 6N tellurium raw material in the annular zone melting boat; the temperature of the continuous zone melting is 500-800 °C, the rate is 0.5-5 mm / min, the number of times is 10-30 times, and the width is 5-10 cm; After the zone melting work is completed, the transmission heating unit is turned off, and the temperature in the furnace is reduced to room temperature. The vacuum unit is turned off, the annular zone melting boat is taken out, and 15 cm at both ends of the annular zone melting boat is removed. After the middle part is demolded, 7N high-purity tellurium is obtained.

9. The method for preparing 7N high-purity tellurium according to claim 8, characterized in that: The temperature of the continuous zone melting is 650-750°C, the speed is 2-5 mm / min, the number of times is 10-20 times, and the width is 8-10 cm; The vacuum degree in the furnace is 1 Pa-10 Pa.

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