Vacuum sintering device

Abstract

The utility model belongs to the technical field of quartz sand preparation, and particularly relates to a vacuum sintering device. The vacuum sintering device provided by the utility model can provide a vacuum environment for quartz sand preparation, impurities in gas-liquid inclusion can be more effectively removed in a high-temperature vacuum state, the purity of the quartz sand is improved, the vacuum environment has no pollution source, and the quality of the quartz sand can be effectively controlled. Meanwhile, the vacuum environment is beneficial to inhibiting volatilization and diffusion of some impurities and preventing the impurities from entering the quartz sand again; the high-temperature vacuum state is beneficial to removal of hydroxyl in the quartz sand. According to the vacuum sintering device provided by the utility model, quartz sand can be prepared by adopting single equipment, the prepared quartz sand is high in purity which is more than 99.998%, the hydroxyl content is low, the hydroxyl content is less than 1ppm, the granularity is 0.1-0.3 mm, the quartz sand can be used as a raw material of inner-layer sand of a photovoltaic or semiconductor quartz crucible, meanwhile, the production efficiency is improved, and the vacuum sintering device is green and environment-friendly.

Description

Technical Field

[0001] This utility model belongs to the field of quartz sand preparation technology, specifically relating to a vacuum sintering device. Background Technology

[0002] Currently, the main methods for preparing quartz sand include the low-temperature freeze-thaw-microwave assisted method and the sol-gel method. However, these methods require multiple pieces of equipment to remove impurities and hydroxyl groups. Even slight changes in any parameter, such as the microwave exposure time, freeze-thaw temperature, and time, can affect the quality and performance of the product. This places high demands on the operators' technical skills and experience, increasing the difficulty and cost of large-scale industrial production. Furthermore, these equipments have shortcomings in precision, reliability, and stability, leading to imprecise temperature or pressure control, which affects the removal of impurities and hydroxyl groups during quartz sand preparation, resulting in a product purity that does not reach 99%. Utility Model Content

[0003] The purpose of this invention is to provide a vacuum sintering device. The device provided by this invention has good precision, reliability and stability, and can complete the preparation of quartz sand in an integrated manner with a quartz sand purity of over 99.998%.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] This utility model provides a vacuum sintering apparatus, including a sealing system; a heating system for heating the sealing system; and a vacuum system connected to the sealing system.

[0006] The sealing system includes a chamber; a cap that covers the chamber, the top of the cap having an opening; a guide rod extending into the chamber through the opening; and a container connected to one end of the guide rod extending into the chamber.

[0007] Preferably, the guide rod moves up and down reciprocally; the guide rod rotates around its own central axis.

[0008] Preferably, the cap moves up and down reciprocally; the cap rotates around its own central axis; and the central axis of the cap coincides with the central axis of the guide rod.

[0009] Preferably, the diameter of the hole is the same as the diameter of the guide rod.

[0010] Preferably, the container moves synchronously with the guide rod; the container moves up and down reciprocally with the guide rod.

[0011] Preferably, the container rotates around its own central axis with the guide rod; the central axis of the container coincides with the central axis of the guide rod.

[0012] Preferably, the container is made of high-purity graphite; the ash content of the high-purity graphite is ≤20ppm and the metal impurity content is ≤0.5ppm.

[0013] Preferably, the central axis of the chamber coincides with the central axis of the guide rod; the chamber is sealed to the cover via a flange.

[0014] Preferably, the heating system is a heating chamber; the central axis of the heating chamber coincides with the central axis of the guide rod.

[0015] Preferably, the vacuum system includes a vacuum pump; the vacuum pump is connected to the chamber via a vacuum pipe.

[0016] This invention provides a vacuum sintering apparatus. The vacuum sintering apparatus provided by this invention is low in cost, easy to operate, and has good stability. The vacuum sintering apparatus provides a vacuum environment for the preparation of quartz sand. Under high-temperature vacuum conditions, a huge pressure difference is formed between the inside and outside of the gas-liquid inclusions, causing them to burst. Simultaneously, the gas-liquid inclusions in the quartz sand expand due to heat, and as the quartz sand lattice deforms, it ruptures with the change in lattice volume, exposing the impurities inside the inclusions. These impurities are then vaporized and diffused out due to the concentration difference between the inside and outside, thus more effectively removing impurities from the gas-liquid inclusions and improving the purity of the quartz sand. Furthermore, the preparation of quartz sand in a vacuum environment is free of pollution sources, avoiding contact with oxygen, water vapor, and other impurities in the air, reducing the possibility of impurities adsorbing on the quartz sand surface or reacting chemically with the quartz sand, and effectively controlling the quality of the quartz sand. At the same time, the vacuum environment helps to suppress the volatilization and diffusion of some impurities, preventing them from re-entering the interior of the quartz sand. High temperature and vacuum conditions are beneficial for removing hydroxyl groups from quartz sand. Hydroxyl groups in quartz can affect the transparency, softening temperature, viscosity and other properties of quartz glass. Removing hydroxyl groups is crucial for improving the quality of quartz sand.

[0017] The vacuum sintering device provided by this invention can complete the preparation of quartz sand with a single device. The prepared quartz sand has high purity, above 99.998%, low hydroxyl content, below 1 ppm, and particle size of 0.1-0.3 mm. It can be used as raw material for the inner layer sand of photovoltaic or semiconductor quartz crucibles, while improving production efficiency and being environmentally friendly. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 An exploded view of the vacuum sintering apparatus provided by this utility model;

[0020] Figure 2 A schematic diagram of the vacuum sintering device provided by this utility model after it is closed;

[0021] Reference numerals: 1 is the guide rod, 2 is the cap, 3 is the container, 4 is the chamber, 5 is the heating chamber, 6 is the vacuum pipe, 7 is the vacuum pump, 8 is the hole, 10 is the sealing system, 20 is the heating system, 30 is the vacuum system, 51 is the heating component, 52 is the heat preservation component, and 53 is the temperature control component. Detailed Implementation

[0022] This utility model provides a vacuum sintering apparatus, including a sealing system 10; a heating system 20 for heating the sealing system 10; and a vacuum system 30 connected to the sealing system 10.

[0023] The sealing system 10 includes a chamber 4; a cover 2 that closes to the chamber 4, the top of the cover 2 having a hole 8; a guide rod 1 that extends into the chamber 4 through the hole 8; and a container 3 connected to one end of the guide rod 1 that extends into the chamber 4.

[0024] The vacuum sintering apparatus provided by this utility model includes a sealing system 10; the guide rod 1 can move up and down reciprocally, and the moving speed can be adjusted; the guide rod 1 can rotate around its own central axis, and the rotation speed can be adjusted; the rotation speed of the guide rod 1 can be no more than 5 rpm, specifically 1 rpm or 3 rpm.

[0025] In this invention, the guide rod 1 is made of 316L stainless steel, has a water-cooled structure, and a mirror-polished surface. By employing the aforementioned rust-resistant materials and surface treatment process, this invention ensures that the silica powder is not contaminated during the dehydroxylation and calcination processes, thus maintaining the final purity of the quartz sand and effectively guaranteeing product quality.

[0026] In this invention, the cover 2 can move up and down reciprocally, and the moving speed can be adjusted; the cover 2 can rotate around its own central axis, and the rotation speed can be adjusted; the central axis of the cover 2 can coincide with the central axis of the guide rod 1.

[0027] In this invention, the diameter of the hole 8 can be the same as the diameter of the guide rod 1.

[0028] In this invention, the cap 2 is made of 316L stainless steel, has a water-cooled structure, and a mirror-polished surface. By employing the aforementioned rust-resistant materials and surface treatment process, this invention ensures that the silica powder is not contaminated during the dehydroxylation and calcination processes, thus maintaining the final purity of the quartz sand and effectively guaranteeing product quality.

[0029] In this invention, the container 3 and the guide rod 1 can move synchronously; the container 3 can move up and down with the guide rod 1, and the moving speed can be adjusted; the container 3 can rotate around its own central axis with the guide rod 1, and the rotation speed can be adjusted; the central axis of the container 3 can coincide with the central axis of the guide rod 1.

[0030] In this invention, the container 3 can be made of high-purity graphite; the ash content of the high-purity graphite can be ≤20ppm, and the content of metallic impurities can be ≤0.5ppm. By using the above-mentioned high-purity materials, this invention can ensure that the silica powder is not contaminated during the dehydroxylation and calcination process, and does not affect the final purity of the quartz sand, thus effectively guaranteeing product quality.

[0031] In this invention, the central axis of the chamber 4 can coincide with the central axis of the guide rod 1; the chamber 4 can be sealed to the cover 2 via a flange.

[0032] In this invention, the chamber 4 is made of 316L stainless steel, has a water-cooled structure, and a mirror-polished surface. The rust-resistant material and surface treatment process ensure that the silica powder is not contaminated during the dehydroxylation and calcination process, and does not affect the final purity of the quartz sand, thus effectively guaranteeing product quality.

[0033] The vacuum sintering apparatus provided by this utility model includes a heating system 20; the heating system 20 can be a heating chamber 5; the central axis of the heating chamber 5 can coincide with the central axis of the guide rod 1; the heating chamber 5 can be provided with a heating component 51; the heating chamber 5 can be provided with a heat preservation component 52; the heating chamber 5 can be provided with a temperature control component 53; the temperature range of the heating chamber 5 can be 0~1800℃.

[0034] In this invention, the heating component 51 can be made of high-purity graphite; the ash content of the high-purity graphite can be ≤20ppm, and the content of metallic impurities can be ≤0.5ppm. By using the above-mentioned high-purity materials, this invention can ensure that the silica powder is not contaminated during the dehydroxylation and calcination process, and does not affect the final purity of the quartz sand, thus effectively guaranteeing product quality.

[0035] The vacuum sintering apparatus provided by this invention includes a vacuum system 30; the vacuum system 30 may include a vacuum pump 7; the vacuum pump 7 may be connected to the chamber 4 via a vacuum pipe 6. This invention uses the vacuum system 30 to evacuate the sealing system 10, thus placing the silica powder in a vacuum environment.

[0036] The disassembled structure of the vacuum sintering device provided by this utility model is as follows: Figure 1 As shown, the device includes a sealing system 10, a heating chamber 5 (heating system 20) for heating the sealing system 10, and a vacuum pump 7 (vacuum system 30) connected to the sealing system 10 via a vacuum pipe 6. The sealing system 10 includes a chamber 4, a cover 2 that closes to the chamber 4, a hole 8 at the top of the cover 2, a guide rod 1 extending into the chamber 4 through the hole 8, and a container 3 connected to one end of the guide rod 1 extending into the chamber 4. Both the guide rod 1 and the cover 2 can move independently up and down along the central axis. As the guide rod 1 descends, the container 3 first enters the chamber 4, then the cover 2 contacts the chamber 4 and stops moving, forming a sealed chamber. The guide rod 1 and the container 3 continue to descend to a set position in the chamber 4 that surrounds the heating chamber 5 and then stop. The guide rod 1 then rotates to heat the raw material evenly. The closed vacuum sintering device is as follows: Figure 2 As shown.

[0037] To further illustrate this utility model, the following detailed description of the utility model's solution is provided in conjunction with the accompanying drawings and embodiments, but these descriptions should not be construed as limiting the scope of protection of this utility model.

[0038] Example 1

[0039] This embodiment provides a vacuum sintering apparatus, including a sealing system 10. The sealing system 10 includes a chamber 4, a cover 2 that covers the chamber 4, a hole 8 on the top of the cover 2, a guide rod 1 that extends into the chamber 4 through the hole 8, the diameter of the hole 8 being the same as the diameter of the guide rod 1, and a container 3 connected to one end of the guide rod 1 that extends into the chamber 4.

[0040] The guide rod 1, the cap 2, and the chamber 4 are made of 316L stainless steel, have a water-cooled structure, and a mirror-polished surface. The guide rod 1 and the cap 2 can move up and down and rotate around their own central axis. The container 3 moves synchronously with the guide rod 1. The container 3 moves up and down with the guide rod 1 and rotates around its own central axis. The chamber 4 is sealed to the cap 2 via a flange. The central axes of the cap 2, the container 3, and the chamber 4 coincide with the central axis of the guide rod 1. The container 3 is made of high-purity graphite.

[0041] The heating system 20 heats the sealing system 10. The heating system 20 is a heating chamber 5. The central axis of the heating chamber 5 coincides with the central axis of the guide rod 1. The heating chamber 5 is provided with a heating component 51, a heat preservation component 52 and a temperature control component 53. The heating component 51 is made of high-purity graphite. The temperature range of the heating chamber 5 is 0 to 1800°C.

[0042] A vacuum system 30 is connected to the sealing system 10, and the vacuum system 30 includes a vacuum pump 7; the vacuum pump 7 is connected to the chamber 4 through a vacuum pipe 6.

[0043] Application Example 1

[0044] (1) 100 kg of silica powder with a particle size of 0.1-0.3 mm and a purity of 99.99985% is filled into container 3 and sent to heating chamber 5.

[0045] (2) Start vacuum pump 7 to draw a vacuum until the vacuum degree is ≤0.01Pa.

[0046] (3) Start heating chamber 5 to start heating and temperature rise from 0℃ to 800℃. The heating rate at this stage is 200℃ / h, which is used to preheat the entire chamber 4 and remove water vapor molecules from the sealing system 10 and heating system 20.

[0047] (4) Keep the temperature at 800℃ for 4 hours to further preheat the entire chamber 4, and adjust the vacuum degree of the preheated chamber 4 to a stable state, with a vacuum degree ≤0.01Pa.

[0048] (5) Heat to 1100℃ at a heating rate of 100℃ / h.

[0049] (6) Keep at 1100℃ for 12 hours to allow the silica powder to be fully dehydroxylated.

[0050] (7) Stir the silica powder in container 3 evenly, and simultaneously heat it to the calcination temperature of 1600℃ at a heating rate of 200℃ / h.

[0051] (8) Keep warm at 1600℃ for 3 hours.

[0052] (9) Cool down to 1100℃ and keep warm for 3 hours.

[0053] (10) Stop heating, cool down to room temperature, and introduce high-purity nitrogen gas to obtain low-hydroxyl, high-purity quartz sand.

[0054] Application Example 2

[0055] (1) 100 kg of silica powder with a particle size of 0.1-0.3 mm and a purity of 99.99985% is filled into container 3 and sent to heating chamber 5.

[0056] (2) Start vacuum pump 7 to draw a vacuum until the vacuum degree is ≤0.01Pa.

[0057] (3) Start heating chamber 5 to start heating and temperature rise from 0℃ to 800℃. The heating rate at this stage is 200℃ / h, which is used to preheat the entire chamber 4 and remove water vapor molecules from the sealing system 10 and heating system 20.

[0058] (4) Keep the temperature at 800℃ for 4 hours to further preheat the entire chamber 4, and adjust the vacuum degree of the preheated chamber 4 to a stable state, with a vacuum degree ≤0.01Pa.

[0059] (5) Heat to 1200℃ at a heating rate of 100℃ / h.

[0060] (6) Keep at 1200℃ for 6 hours to allow the silica powder to be fully dehydroxylated.

[0061] (7) Stir the silica powder in container 3 evenly, and simultaneously heat it to the calcination temperature of 1600℃ at a heating rate of 200℃ / h.

[0062] (8) Keep warm at 1600℃ for 2 hours.

[0063] (9) Cool down to 1100℃ and keep warm for 2 hours.

[0064] (10) Stop heating, cool down to room temperature, and introduce high-purity nitrogen gas to obtain low-hydroxyl, high-purity quartz sand.

[0065] Application Example 3

[0066] 1) Fill container 3 with 100 kg of silica powder with a particle size of 0.1-0.3 mm and a purity of 99.99985% and send it to heating chamber 5.

[0067] (2) Start vacuum pump 7 to draw a vacuum until the vacuum degree is ≤0.01Pa.

[0068] (3) Start heating chamber 5 to start heating and temperature rise from 0℃ to 800℃. The heating rate at this stage is 200℃ / h, which is used to preheat the entire chamber 4 and remove water vapor molecules from the sealing system 10 and heating system 20.

[0069] (4) Keep the temperature at 800℃ for 4 hours to further preheat the entire chamber 4, and adjust the vacuum degree of the preheated chamber 4 to a stable state, with a vacuum degree ≤0.01Pa.

[0070] (5) Heat to 1200℃ at a heating rate of 50℃ / h.

[0071] (6) Keep at 1200℃ for 12 hours to allow the silica powder to be fully dehydroxylated.

[0072] (7) Stir the silica powder in container 3 evenly, and simultaneously heat it to the calcination temperature of 1700℃ at a heating rate of 100℃ / h.

[0073] (8) Keep warm at 1700℃ for 4 hours.

[0074] (9) Cool down to 1100℃ and keep warm for 3 hours.

[0075] (10) Stop heating, cool down to room temperature, and introduce high-purity nitrogen gas to obtain low-hydroxyl, high-purity quartz sand.

[0076] Comparative Application Example 1

[0077] The preparation method of this comparative application example is the same as that of application example 1, except that conventional high-temperature resistant equipment is used and the vacuum degree is adjusted to 5 Pa.

[0078] Comparative Application Example 2

[0079] The preparation method of this comparative application example is the same as that of application example 1, except that conventional atmospheric pressure high temperature resistant equipment is used, and steps (6), (8) and (9) are carried out under atmospheric pressure conditions.

[0080] Test Example 1

[0081] The quartz sand corresponding to Example 1 and Comparative Application Examples 1-2 was subjected to purity detection by inductively coupled plasma mass spectrometry (ICP-MS) and hydroxyl content detection by Fourier transform infrared spectroscopy. The results are shown in Tables 1 and 2.

[0082] Table 1. Parameters of quartz sand in Application Example 1

[0083]

[0084] Table 2 compares the quartz sand parameters in Application Examples 1 and 2.

[0085] project purity Particle size Hydroxyl content Comparative Application Example 1 No change No change 100ppm Comparative Application Example 2 No change No change 2000ppm

[0086] As can be seen from Tables 1 and 2, compared with Application Example 2, under normal pressure conditions, some quartz powder is still in an amorphous state and has not been completely transformed into a crystalline state. However, the device of this invention can achieve high vacuum conditions, and the quartz sand prepared has the advantages of high purity, low hydroxyl content and large particle size.

[0087] As can be seen from the above embodiments, the device provided by this utility model can prepare high-purity, low-hydroxyl-content quartz sand with large particle size, which is suitable for preparing quartz sand.

[0088] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. Other embodiments can be obtained based on the present embodiments without creative intent, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A vacuum sintering apparatus, characterized in that, Includes a sealing system (10); a heating system (20) for heating the sealing system (10); and a vacuum system (30) connected to the sealing system (10); The sealing system (10) includes a chamber (4); a cover (2) that closes to the chamber (4), the top of the cover (2) having a hole (8); a guide rod (1) that extends into the chamber (4) through the hole (8); and a container (3) connected to one end of the guide rod (1) that extends into the chamber (4).

2. The vacuum sintering apparatus according to claim 1, characterized in that, The guide rod (1) moves up and down reciprocally; the guide rod (1) rotates around its own central axis.

3. The vacuum sintering apparatus according to claim 1, characterized in that, The cover (2) moves up and down repeatedly; the cover (2) rotates around its own central axis; the central axis of the cover (2) coincides with the central axis of the guide rod (1).

4. The vacuum sintering apparatus according to claim 1 or 2, characterized in that, The diameter of the hole (8) is the same as the diameter of the guide rod (1).

5. The vacuum sintering apparatus according to claim 1, characterized in that, The container (3) moves synchronously with the guide rod (1); the container (3) moves up and down back and forth with the guide rod (1).

6. The vacuum sintering apparatus according to claim 1 or 5, characterized in that, The container (3) rotates around its own central axis with the guide rod (1); the central axis of the container (3) coincides with the central axis of the guide rod (1).

7. The vacuum sintering apparatus according to claim 1 or 5, characterized in that, The container (3) is made of high-purity graphite; the ash content of the high-purity graphite is ≤20ppm and the metal impurity content is ≤0.5ppm.

8. The vacuum sintering apparatus according to claim 1, characterized in that, The central axis of the chamber (4) coincides with the central axis of the guide rod (1); the chamber (4) is sealed to the cover (2) through a flange.

9. The vacuum sintering apparatus according to claim 1, characterized in that, The heating system (20) is a heating chamber (5); the central axis of the heating chamber (5) coincides with the central axis of the guide rod (1).

10. The vacuum sintering apparatus according to claim 1, characterized in that, The vacuum system (30) includes a vacuum pump (7); the vacuum pump (7) is connected to the chamber (4) via a vacuum pipe (6).

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