Tellurium ingot casting method

Abstract

The present invention belongs to the field of metal casting technology and discloses a tellurium ingot casting method, comprising the following steps: Step 1: pouring liquid tellurium into a mold; Step 2: conveying the mold, and using flowing nitrogen to protect and cool it during the conveying process; Step 3: removing the tellurium ingot from the mold. In Step 1, the tellurium in the mold has a temperature of 300-400°C; in Step 2, the conveying time T is 15-25 minutes, the nitrogen flow rate is 12-20 m / s, and the tellurium in the mold cools down at a rate of 16-20°C / min during the first 15 minutes. The present invention limits the nitrogen flow rate, thereby controlling the cooling rate of the tellurium ingot before it reaches the demolding temperature, resulting in a smooth, crack-free surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal casting, and more specifically, relates to a tellurium ingot casting method. Background Art

[0002] Metal ingots are widely used in high-purity metal preparation, organic metal vapor deposition, organic metal preparation and other fields. The lock products made from them are widely used in aerospace, semiconductors, infrared and other high-tech fields. As an essential semi-finished raw material, the quality of metal ingots is particularly important.

[0003] Among them, tellurium ingots, as the raw material source for thermoelectric materials, refrigeration materials, and infrared materials, have relatively high quality requirements.

[0004] In industrial production, metal ingots are cast through a casting process. Chinese patent 201420515733.4 discloses an automatic metal silicon casting production line, which includes a tilting device, a frame, a conveying system, a cooling system and several ingot molds. The conveying system is supported on the frame, and both sides of each ingot mold are respectively connected to the conveying system. A flow channel is provided below the tilting device, and the outlet end of the flow channel corresponds to the inner cavity of at least one ingot mold; the cooling system includes a spraying device and several cooling rollers, the spraying device includes several first cooling pipes and several second cooling pipes, and the cooling rollers are arranged above the conveying system; a post-demolding conveying device is provided on the side of the conveying system away from the tilting device, and a finished product silo is provided at the discharge port of the post-demolding conveying device. A level meter, a thermometer and a third cooling pipe are provided in the finished product silo, and a fully automatic weighing and packaging machine is provided below the finished product silo.

[0005] The above patent uses a combination of a pouring device, a conveying system, a cooling system and an ingot mold to allow the molten metal liquid to be poured into the ingot mold and then cooled step by step to form a metal ingot. It has a high degree of automation and requires fewer people, effectively reducing the labor intensity of workers. In addition, the shape and size of the products are consistent, and it is a casting production line with excellent casting effect. In addition, the above patent also introduces the cooling of the molten metal liquid in the ingot mold by accelerating the cooling by air cooling, nitrogen, water cooling, etc., and the cooling effect is good.

[0006] However, when the technical solution of the above patent is used in the production of tellurium ingots, since the tellurium liquid in a high-temperature state easily forms an oxide layer when it comes into contact with external oxygen, the above patent, while cooling the tellurium liquid, also causes multiple layers of oxide layers to exist inside the formed tellurium ingot, causing the interior of the tellurium ingot to be brittle and prone to cracking, seriously affecting the quality of the tellurium ingot.

[0007] In response to this technical problem, Chinese patent 202123266142.7 discloses a nitrogen-oxygen-free cooling system for casting products, including: an anaerobic environment box and a main body support. The anaerobic environment box is installed on the main body support, and has a first accommodating chamber inside. The main body support has a second accommodating chamber inside. The first accommodating chamber and the second accommodating chamber are connected to form a through chamber. Two groups of cooling structures are provided in the through chamber, and the bottoms of the two groups of cooling structures are respectively installed on the two side walls of the main body support; at least one oxygen overflow valve is provided on the top of the anaerobic environment box; the anaerobic environment box is used to provide an anaerobic environment for the cast product to prevent the product from reacting with oxygen in the air during the cooling process, causing oxidation of the product surface.

[0008] The above patent uses nitrogen to keep the entire casting box in an oxygen-free environment, and the nitrogen flow rate can be adjusted according to the cast product. It is flexible to operate and can avoid the formation of an oxide layer during the cooling process of the tellurium ingot, effectively ensuring the quality of the tellurium ingot.

[0009] However, the above patent does not disclose the specific method of nitrogen cooling. In actual production, when a large number of tellurium ingots are cast, the cooling rate of the tellurium ingot is a very critical factor: if the surface of the tellurium ingot is cooled too quickly, the surface of the tellurium ingot will begin to solidify during the cooling process but the internal temperature of the tellurium ingot will be too high. The temperature difference between the inside and outside of the tellurium ingot will be too large, causing stress on the surface of the tellurium ingot during cooling, resulting in surface cracks; but if the surface of the tellurium ingot is cooled too slowly, it will seriously affect the production efficiency of the tellurium ingot.

[0010] Therefore, during the casting process of tellurium ingots, reasonably controlling the surface cooling rate of tellurium ingots has become a technical problem. Summary of the Invention

[0011] The main purpose of the present invention is to provide a method for casting a tellurium ingot, so as to solve the problem in the prior art that during the casting process of the tellurium ingot, the cooling speed of the tellurium ingot is too fast or too slow, resulting in reduced quality of the tellurium ingot.

[0012] Based on the above objectives, the present invention provides a method for casting a tellurium ingot, comprising the following steps:

[0013] Step 1: Casting liquid tellurium into a mold;

[0014] Step 2: Transport the mold. During the transportation process, use flowing nitrogen to protect and cool it down.

[0015] Step 3: Take out the tellurium ingot from the mold;

[0016] In step 1, the temperature of the tellurium in the mold is 300-400°C;

[0017] In step 2, the conveying time T is 15 to 25 minutes, the nitrogen flow rate is 12 to 20 m / s, and the cooling rate of the tellurium in the mold in the first 15 minutes is 15 to 20° C. / min.

[0018] Preferably, in step 1, the casting speed of tellurium is 35-45 g / s; and the temperature of the tellurium solution before casting is 300-400°C.

[0019] Preferably, in step 2, when the conveying time is 1 / 2T, the temperature of the tellurium in the mold is 130-180°C.

[0020] Preferably, the mold has a draft angle; and the tellurium ingot in step 3 is demolded by flipping the mold.

[0021] More preferably, the casting is carried out using the following system:

[0022] The tellurium ingot casting system includes a pouring ladle and a cover body, wherein the pouring ladle is arranged on the cover body, a pouring port penetrating into the cover body is arranged at the bottom of the pouring ladle, a first conveyor line is arranged in the cover body, a plurality of workstations are arranged on the first conveyor line, each workstation is provided with a mold, and the pouring port is located above one of the molds at one end of the first conveyor line; a nitrogen pipe for blowing nitrogen into the cover body is provided at one end of the cover body close to the pouring port, an exhaust pipe is provided at one end of the cover body away from the pouring port, and an oxygen detector is provided in the cover body.

[0023] Furthermore, a guide plate and a second conveyor line are provided in the cover body. The guide plate and the second conveyor line are provided below an end of the first conveyor line away from the pouring port. The guide plate is used to guide the tellurium ingot to the second conveyor line.

[0024] Furthermore, a hammer for striking the edge of the mold is provided at one end of the first conveying line away from the pouring gate.

[0025] Furthermore, a cavity is provided in the pouring ladle, the top opening of the cavity is a liquid inlet, and the pouring port is provided at the bottom of the cavity.

[0026] Furthermore, a drive motor and a plug rod are provided above the cavity, and the drive motor drives the plug rod to close or open the pouring port; a liquid level probe is also provided on the pouring ladle, and the liquid level probe is set at a preset liquid level height in the cavity and is linked to the drive motor.

[0027] Furthermore, a heating wire and a temperature probe are provided in the casting ladle, the detection end of the temperature probe extends into the cavity, and the heating wire ring is provided outside the cavity.

[0028] Compared with the prior art, the present invention has at least the following advantages:

[0029] (1) The present invention limits the nitrogen flow rate, thereby controlling the cooling rate of the tellurium ingot before it reaches the demoulding temperature, so that the surface of the produced tellurium ingot is smooth and free of cracks;

[0030] (2) The present invention provides a tellurium ingot casting system. The use of the tellurium ingot casting system in conjunction with the tellurium ingot casting method of the present invention can produce tellurium ingots more quickly and continuously with a high degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0032] Figure 1 A schematic structural diagram of an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of a pouring ladle according to an embodiment of the present invention;

[0034] Figure 3 This is a front view of the internal structure of the cover body according to an embodiment of the present invention;

[0035] Figure 4 A top view of the internal structure of the cover body according to an embodiment of the present invention;

[0036] 1. Pouring ladle, 2. Drive motor, 3. Stopper rod, 4. Heating wire, 5. Liquid level probe, 6. Temperature probe, 7. Cavity, 8. Pouring gate, 9. Ladle, 10. Channel, 11. Cover, 12. First conveyor line, 13. Mold, 14. Guide plate, 15. Second conveyor line, 16. Beating hammer, 17. Nitrogen pipe, 18. Oxygen detector, 19. Exhaust pipe. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0038] The following disclosure provides many different embodiments or examples for implementing different solutions of the present invention.

[0039] Example 1

[0040] Reference Figures 1 to 4As shown, the present invention provides a tellurium ingot casting system, including a pouring ladle 1 and a cover body 11, the pouring ladle 1 is arranged on the cover body 11, and a pouring port 8 penetrating into the cover body 11 is provided at the bottom of the pouring ladle 1, a first conveyor line 12 is provided in the cover body 11, 45 workstations are provided on the first conveyor line 12, and a mold 13 is provided on each workstation, and the pouring port 8 is located above one of the molds 13 at one end of the first conveyor line 12; a nitrogen pipe 17 for blowing nitrogen into the cover body 11 is provided at one end of the cover body 11 close to the pouring port 8, and an exhaust pipe 19 is provided at one end of the cover body 11 away from the pouring port 8.

[0041] In actual application, before casting the tellurium ingot, it is necessary to first introduce nitrogen into the cover body 11 through the nitrogen pipe 17 to squeeze out the air in the cover body 11 from the exhaust pipe 19. After a period of nitrogen introduction, the cover body 11 is already in a low-oxygen environment or even an oxygen-free environment; then the molten tellurium liquid is poured from the pouring port 8 of the pouring ladle 1 into the mold 13 on the first station, and the first conveyor line 12 is started to move so that the mold 13 filled with tellurium liquid moves forward one station, and the above steps are repeated one by one so that the molds 13 above the first conveyor line 12 are all filled with tellurium liquid; in this process, the tellurium liquid in the mold 13 will be purged and cooled by nitrogen during the forward movement, slowly cooling the formed tellurium ingot and reaching the demolding temperature, and then the tellurium ingot already at the 21st station falls off from the mold 13 under its own weight under the turning of the first conveyor line 12; the above operations are repeated to realize the continuous production of tellurium ingot casting.

[0042] Preferably, an oxygen detector 18 is further provided in the cover 11 for confirming that the oxygen concentration inside the cover 11 is lower than the requirement for casting tellurium ingots, ensuring that the oxygen concentration is no longer sufficient to form an oxide layer during the cooling process of the tellurium liquid.

[0043] Preferably, a cavity 7 is provided in the casting ladle 1 , the top of the cavity 7 is open and serves as a liquid inlet, and the pouring port 8 is provided at the bottom of the cavity 7 .

[0044] More preferably, a drive motor 2 and a plug rod are provided above the cavity 7, and the drive motor 2 drives the plug rod 3 to close or open the pouring port 8; a liquid level probe 5 is also provided on the pouring ladle 1, and the liquid level probe 5 is set at a preset liquid level height in the cavity 7 and is linked to the drive motor 2.

[0045] In actual application, in order to ensure that the weight of the tellurium liquid on each mold 13 is consistent, the plug rod can be driven by the driving motor 2 to close the pouring gate 8, and then the molten tellurium liquid is guided from the external ladle 9 through the channel 10 and enters the cavity 7 from the liquid inlet. When the liquid level probe 5 in the cavity 7 detects that the tellurium liquid in the cavity 7 reaches the preset liquid level, the ladle 9 is stopped from pouring the tellurium liquid, and then the plug rod is driven to open the pouring gate 8, and the tellurium liquid in the cavity 7 is injected into the mold 13 from the pouring gate 8.

[0046] The following examples and comparative examples were all cast using the tellurium ingot casting system of Example 1.

[0047] Example 2

[0048] A tellurium ingot is prepared by the following steps:

[0049] Step 1: 3 kg of liquid tellurium is poured into a mold. The temperature of the tellurium in the mold is 350°C.

[0050] Step 2: The mold is transported for 25 minutes. During the transportation process, nitrogen is introduced at a rate of 12 m / s for protection and cooling so that the cooling rate of the mold in the first 15 minutes is 16°C / min;

[0051] Step 3: Take out the tellurium ingot from the mold.

[0052] Example 3

[0053] A tellurium ingot is prepared by the following steps:

[0054] Step 1: 3 kg of liquid tellurium is poured into a mold. The temperature of the tellurium in the mold is 350°C.

[0055] Step 2: The mold is transported for 15 minutes. During the transportation process, nitrogen is introduced at 20 m / s for protection and cooling so that the cooling rate of the mold is 20°C / min;

[0056] Step 3: Take out the tellurium ingot from the mold.

[0057] Example 4

[0058] A tellurium ingot is prepared by the following steps:

[0059] Step 1: 3 kg of liquid tellurium is poured into a mold. The temperature of the tellurium in the mold is 350°C.

[0060] Step 2: The mold is transported for 20 minutes. During the transportation process, nitrogen is introduced at 17 m / s for protection and cooling so that the cooling rate of the mold in the first 15 minutes is 18°C / min;

[0061] Step 3: Take out the tellurium ingot from the mold.

[0062] Comparative Example 1

[0063] A tellurium ingot is prepared by the following steps:

[0064] Step 1: 3 kg of liquid tellurium is poured into a mold. The temperature of the tellurium in the mold is 350°C.

[0065] Step 2: The mold is transported for 25 minutes. During the transportation process, nitrogen is introduced at 21 m / s for protection and cooling so that the cooling rate of the mold in the first 15 minutes is 22°C / min;

[0066] Step 3: Take out the tellurium ingot from the mold;

[0067] Result: There were cracks on the surface of the removed tellurium ingot. The reason was that during the cooling process, the surface of the tellurium ingot had begun to solidify but the internal temperature of the tellurium ingot was too high. The temperature difference between the inside and outside of the tellurium ingot was too large, which caused stress on the surface of the tellurium ingot when it cooled, resulting in surface cracks.

[0068] According to the results of Examples 2-4 and Comparative Example 1, excessively fast nitrogen purging can lead to quality problems such as cracks in the tellurium liquid in the mold during the cooling and molding process; while excessively slow nitrogen purging can affect the production efficiency of the entire production line and reduce the casting efficiency of the tellurium ingot. The technical solution adopted in the present invention controls the cooling and molding speed of the tellurium liquid in the first 15 minutes by controlling the nitrogen purging flow rate, thereby ensuring that the tellurium ingot can be smoothly demolded while also guaranteeing its quality.

[0069] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for casting a tellurium ingot, characterized in that: The steps include: Step 1: Casting liquid tellurium into a mold; Step 2: Transport the mold. During the transportation process, use flowing nitrogen to protect and cool it down. Step 3: Take out the tellurium ingot from the mold; In step 1, the temperature of the tellurium in the mold is 300-400°C; the casting speed of the tellurium is 35-45g / s; the temperature of the tellurium liquid before casting is 300-400°C, and the casting amount of the tellurium liquid in the mold is 3kg; In step 2, the conveying time T is 15-25 minutes, the nitrogen flow rate is 12-20 m / s, and the cooling rate of the tellurium in the mold in the first 15 minutes is 16-20°C / min. When the conveying time is 1 / 2T, the temperature of the tellurium in the mold is 130-180°C.

2. The tellurium ingot casting method according to claim 1, characterized in that: The mold has a draft angle; the tellurium ingot in step 3 is demoulded by flipping the mold.

3. The tellurium ingot casting method according to claim 1, characterized in that: The casting is carried out using the following system: The tellurium ingot casting system includes a pouring ladle and a cover body, wherein the pouring ladle is arranged on the cover body, a pouring port penetrating into the cover body is arranged at the bottom of the pouring ladle, a first conveyor line is arranged in the cover body, a plurality of workstations are arranged on the first conveyor line, each workstation is provided with a mold, and the pouring port is located above one of the molds at one end of the first conveyor line; a nitrogen pipe for blowing nitrogen into the cover body is provided at one end of the cover body close to the pouring port, an exhaust pipe is provided at one end of the cover body away from the pouring port, and an oxygen detector is provided in the cover body.

4. The tellurium ingot casting method according to claim 3, characterized in that: A guide plate and a second conveyor line are further provided in the cover body. The guide plate and the second conveyor line are provided below an end of the first conveyor line away from the pouring port. The guide plate is used to guide the tellurium ingot to the second conveyor line.

5. The tellurium ingot casting method according to claim 3, characterized in that: A striking hammer for striking the edge of the mold is provided at one end of the first conveying line away from the pouring gate.

6. The tellurium ingot casting method according to claim 3, characterized in that: A cavity is provided in the pouring ladle, the top opening of the cavity is a liquid inlet, and the pouring port is provided at the bottom of the cavity.

7. The tellurium ingot casting method according to claim 6, characterized in that: A drive motor and a plug rod are provided above the cavity, and the drive motor drives the plug rod to close or open the pouring port; a liquid level probe is also provided on the pouring ladle, and the liquid level probe is provided at a preset liquid level height in the cavity and is linked to the drive motor.

8. The tellurium ingot casting method according to claim 6, characterized in that: A heating wire and a temperature probe are also provided in the casting ladle. The detection end of the temperature probe extends into the cavity, and the heating wire ring is provided outside the cavity.

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