A method for producing quartz ingot by hydrogen-oxygen flame

Abstract

The application discloses a method for preparing quartz ingot by hydrogen-oxygen flame, and is based on a synthesis device, and comprises the following steps: S1, heating quartz sand raw materials by a hydrogen-oxygen flame torch and falling into a high-temperature melting area on a target holder; S2, rotating the target holder to make the melt centrifugally move outward, and using a plasma torch to perform high-temperature dehydroxy treatment on the moving melt; S3, after the melt passes through the dehydroxy area, the melt enters a cooling area to be cooled; and S4, rotating and descending the target holder to make the melt form a quartz ingot layer by layer by dehydroxyl. By integrating the hydrogen-oxygen flame torch and the plasma torch in the same furnace body, the application solves the long-existing contradiction between "large size" and "low hydroxyl", and successfully prepares a large-size quartz ingot with a diameter of 800 mm and low hydroxyl.

Description

Technical Field

[0001] This invention relates to the field of quartz glass technology, and in particular to a method for preparing quartz ingots using an oxyhydrogen flame. Background Technology

[0002] Quartz ingots (also known as quartz glass ingots, quartz blocks, or quartz glass blanks) are large-sized block-shaped intermediate products of high-purity quartz glass. They are formed by cooling and solidifying molten quartz sand at high temperatures to create a vertical cylindrical or block-shaped blank.

[0003] Currently, the mainstream methods for preparing quartz ingots fall into two main categories: the oxyhydrogen flame method and the plasma method. The oxyhydrogen flame method (also known as the gas refining method) uses an oxyhydrogen flame as a heat source to melt or hydrolyze high-purity quartz sand or silicon-containing precursors (such as SiCl4) in the flame, depositing the melt onto a substrate to form a quartz ingot. The oxyhydrogen flame temperature can reach over 3000℃, enabling the rapid melting of large quantities of quartz raw materials. The process is mature, the equipment is relatively simple, and the production cost is low, making it particularly suitable for preparing large-sized quartz ingots. However, the hydroxyl content in quartz ingots prepared by this method is generally as high as 200ppm-300ppm. High hydroxyl content significantly reduces the softening point, temperature resistance, and mechanical strength of quartz glass, limiting its application in high-end fields.

[0004] The plasma method uses a hydrogen-free flame generated by a plasma device as a heat source to melt and deposit quartz powder onto a target to form a quartz ingot. The plasma flame temperature can reach 3000℃-4000℃, which can fully melt the raw material. Since the working gas is usually dry compressed air or argon, with no hydrogen or oxygen source, the prepared quartz ingot has an extremely low hydroxyl content, only 4ppm-20ppm. However, the plasma method is limited by the heating area and energy density of the plasma flame, making it difficult to efficiently prepare large quartz ingots with a diameter of 500mm or more.

[0005] Current quartz ingot preparation technologies face a dilemma of simultaneously achieving large size and low hydroxyl content: the oxyhydrogen flame method can produce large-sized quartz ingots, but the hydroxyl content is too high; the plasma method can obtain low-hydroxyl products, but it is difficult to achieve large-size production. Therefore, there is an urgent need to develop a new method for preparing quartz ingots that can maintain the ability to produce large-size ingots while effectively reducing the hydroxyl content. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing quartz ingots using an oxyhydrogen flame, so as to solve the problem that the prior art cannot prepare large-sized quartz ingots with low hydroxyl content.

[0007] The objective of this invention is achieved through the following technical solution: a method for preparing quartz ingots using an oxyhydrogen flame, based on a synthesis apparatus, the synthesis apparatus comprising a furnace body and a target holder that rotates and descends inside, a plurality of oxyhydrogen flame torches and plasma torches being arranged above the target holder, the plurality of oxyhydrogen flame torches forming a melting focal point at the center of the target holder, the plurality of plasma torches being radially distributed along the target holder, the plurality of oxyhydrogen flame torches forming a high-temperature melting zone on the target holder, the plurality of plasma torches forming a dehydroxylation zone on the target holder, and a cooling zone being formed between the plasma torches and the edge of the target holder; The preparation method includes the following steps. S1. The quartz sand raw material is heated by an oxyhydrogen torch and falls into the high-temperature melting zone on the target holder; S2. The target holder rotates, causing the melt to move outwards in a centrifugal motion. A plasma torch is used to perform high-temperature dehydroxylation treatment on the moving melt. S3. After passing through the dehydroxylation zone, the melt enters the cooling zone for cooling; S4. The target holder rotates and descends, causing the melt to undergo dehydroxylation layer by layer to form a quartz ingot.

[0008] Preferably, a plurality of protective gas pipes are provided between the oxyhydrogen torch and the plasma torch, the protective gas pipes are arranged around the oxyhydrogen torch, a gap is provided between the protective gas pipes and the oxyhydrogen torch to form an exhaust channel, and an exhaust port matching the exhaust channel is provided on the top of the furnace body.

[0009] Preferably, the air outlet of the protective air tube faces the center of the target holder.

[0010] Preferably, the protective gas tube is filled with nitrogen or helium.

[0011] Preferably, the flow rate ratio of hydrogen to oxygen in the hydrogen-oxygen torch is (2-2.1):1.

[0012] Preferably, the target holder rotates at a constant speed of 12-15 rpm and descends at a constant speed of 0.5-1 mm / min.

[0013] Preferably, the pressure inside the furnace is controlled at 10-100 Pa.

[0014] The obtained quartz ingot has a diameter of 800 mm. The center of the ingot is a high-hydroxyl cylindrical portion with a hydroxyl content of 200-250 ppm, while the remaining portion is a low-hydroxyl cyclic portion with a hydroxyl content of 2-4 ppm. This invention has the following advantages: 1. By integrating an oxyhydrogen torch and a plasma torch into the same furnace body, the oxyhydrogen torch is responsible for melting and depositing quartz sand to form large-sized ingots, while the plasma torch is radially distributed along the target support to perform online high-temperature dehydroxylation treatment on the centrifugally moving melt. This solves the long-standing contradiction between "large size" and "low hydroxyl content", successfully producing large-sized quartz ingots with a diameter of over 800 mm. At the same time, the hydroxyl content in the outer low-hydroxyl region is reduced to 2-4 ppm, and the hydroxyl content in the central high-hydroxyl region is also controlled at 200-250 ppm. This is the first time that large size and ultra-low hydroxyl content have been achieved simultaneously in the same process, breaking through the industry's technical bottleneck. 2. By utilizing the rotation of the target holder to cause the melt to move outwards centrifugally, the plasma torch forms an annular dehydroxylation zone only in the radial half of the target holder, while the central region remains dominated by the oxyhydrogen flame. This naturally forms a concentric layered structure with a high hydroxyl center and a low hydroxyl periphery. The prepared quartz ingot exhibits a unique "dual-quality" partitioning: the central high-hydroxyl cylindrical portion can be used for ordinary quartz products, while the outer low-hydroxyl annular portion can be directly used in high-end fields such as photomask substrates and optical fiber preforms. Simple subsequent cutting allows for sorting and utilization, significantly improving the material's comprehensive utilization rate and product added value. 3. By setting up a protective gas pipe around the oxyhydrogen torch to spray nitrogen or helium to form an isolation gas wall, and opening an exhaust port at the top of the furnace body to match the exhaust channel, the water vapor generated by the oxyhydrogen flame is forcibly discharged, which greatly reduces the water vapor concentration in the furnace and significantly improves the plasma dehydroxylation efficiency. This allows the hydroxyl content in the outer low-hydroxyl area to be as low as 2.7-3.9 ppm, resulting in excellent product quality. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] In the diagram, 1. Target holder; 2. Quartz ingot; 3. Hydrogen-oxygen torch; 4. Plasma torch; 5. Protective gas pipe; 6. Exhaust port; 7. High-temperature melting zone; 8. Dehydroxylation zone; 9. Cooling zone; 10. Furnace body. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] A method for preparing quartz ingots using an oxyhydrogen flame relies on a novel synthesis apparatus, such as... Figure 1As shown, the synthesis apparatus includes a furnace body 10 and a target holder 1 that rotates and descends inside. Both the furnace body 10 and the target holder 1 are conventional structures of existing vertical deposition furnaces. Multiple oxyhydrogen torches 3 and plasma torches 4 are installed above the target holder 1. The multiple oxyhydrogen torches 3 are installed on the top of the furnace body 1 and form a melting focal point at the center of the target holder 1. Preferably, five oxyhydrogen torches 3 are installed, with one in the center and four spaced around the central one. The multiple plasma torches 4 are distributed radially along the target holder 1 in a straight line, occupying half the radius of the entire target holder 1. The multiple oxyhydrogen torches 3 form a circular high-temperature melting zone 7 at the center of the target holder 1, mainly for heating and melting the quartz raw material. The multiple plasma torches 4 form an annular dehydroxylation zone 8 radially along the target holder 1. A cooling zone 9 is formed between the edge of the target holder 1 and the 4. The oxyhydrogen torch 3 can generate a large amount of water vapor, which can bond to form hydroxyl groups after contacting quartz. It must be constrained and quickly guided out. Multiple protective gas pipes 5 are installed at the junction of the high-temperature melting zone 7 and the dehydroxylation zone 8. The protective gas pipes 5 are installed around the oxyhydrogen torch 3 at intervals. Nitrogen or helium gas is sprayed out of the protective gas pipes 5. The protective gas pipes 5 are installed at an angle so that their outlets face the center of the target holder 1. The angle between the protective gas pipes 5 and the surface of the target holder 1 is 30-45°. The protective gas sprayed out by the protective gas pipes 5 can form an isolation wall that prevents water vapor from diffusing outward. A gap is provided between the protective gas pipes 5 and the oxyhydrogen torch 3 to form an annular exhaust channel. An exhaust port 6 matching the exhaust channel is opened on the top of the furnace body 10 to quickly guide the generated gas out.

[0019] Example 1

[0020] A quartz ingot is prepared according to the following steps. S1. Start the hydrogen-oxygen torch 3 to heat the inside of the furnace body 1. The flow ratio of hydrogen to oxygen in the hydrogen-oxygen torch 3 is 2:1. After heating to 800°C, start the protective gas pipe 5 to replace the air in the furnace body 10. Open the exhaust port on the side of the furnace body 10 and control the pressure to 10-100Pa. Then, introduce the quartz sand raw material and heat it through the hydrogen-oxygen torch 3 to form a melt that falls into the high-temperature melting zone 7 on the target holder 1. S2. The target holder 1 rotates at a constant speed of 15 rpm, causing the melt to move outward centrifugally, and the plasma torch 4 is activated to perform high-temperature dehydroxylation treatment on the outward flowing melt. S3. After passing through the dehydroxylation zone 8, the melt enters the cooling zone 9 for cooling and temperature reduction; S4. The target holder 1 descends at a constant speed of 0.5 mm / min, causing the melt to undergo dehydroxylation layer by layer to form quartz ingot 2.

[0021] Performance testing: The quartz ingot prepared in this embodiment has a diameter of Φ802mm, with a diameter deviation of about 2mm. The circumferential surface is smooth and clean. According to infrared spectroscopy, the center of the quartz ingot is a high-hydroxyl cylindrical part with a diameter of 200mm and a hydroxyl content of 215ppm. The remaining part is a low-hydroxyl cyclic part with a hydroxyl content of 2.7ppm.

[0022] Example 2

[0023] A quartz ingot is prepared according to the following steps. S1. Start the hydrogen-oxygen torch 3 to heat the inside of the furnace body 1. The flow ratio of hydrogen to oxygen in the hydrogen-oxygen torch 3 is 2.1:1. After heating to 800℃, start the protective gas pipe 5 to replace the air in the furnace body 10. Open the exhaust port on the side of the furnace body 10 and control the pressure to 10-100Pa. Then, introduce the quartz sand raw material and heat it through the hydrogen-oxygen torch 3 to form a melt that falls into the high-temperature melting zone 7 on the target holder 1. S2. The target holder 1 rotates at a constant speed of 12 rpm, causing the melt to move outward centrifugally, and the plasma torch 4 is activated to perform high-temperature dehydroxylation treatment on the outward flowing melt. S3. After passing through the dehydroxylation zone 8, the melt enters the cooling zone 9 for cooling and temperature reduction; S4. The target holder 1 descends at a constant speed of 1 mm / min, causing the melt to undergo dehydroxylation layer by layer to form quartz ingot 2.

[0024] Performance testing: The quartz ingot prepared in this embodiment has a diameter of Φ803mm, with a diameter deviation of about 3mm. The circumferential surface is smooth and clean. According to infrared spectroscopy, the center of the quartz ingot is a high-hydroxyl cylindrical part with a diameter of 200mm and a hydroxyl content of 223ppm. The remaining part is a low-hydroxyl cyclic part with a hydroxyl content of 3.9ppm.

[0025] Comparative Example A quartz ingot is prepared according to the following steps. S1. Start the hydrogen-oxygen torch 3 to heat the inside of the furnace body 1. The flow ratio of hydrogen to oxygen in the hydrogen-oxygen torch 3 is 2:1. After heating to 800°C, argon gas is introduced into the side opening of the furnace body 10 to replace the internal air. The exhaust port on the side of the furnace body 10 is opened and the pressure is controlled at 10-100Pa. Then, the quartz sand raw material is introduced and heated by the hydrogen-oxygen torch 3 to form a melt that falls into the high-temperature melting zone 7 on the target holder 1. S2. The target holder 1 rotates at a constant speed of 15 rpm and descends at a constant speed of 0.5 mm / min, eventually forming a quartz ingot 2.

[0026] Performance testing: The quartz ingot prepared in this comparative example has a diameter of Φ501mm, with a diameter deviation of about 1mm. The circumferential surface is smooth and clean. The hydroxyl content was detected by infrared spectroscopy to be 268ppm.

[0027] The results above show that by adding a plasma torch treatment process to the existing oxyhydrogen flame synthesis furnace, not only can the original 500mm small quartz ingot be increased to a large 800mm quartz ingot, but the synthesized quartz ingot also has two different qualities: a quartz column with a high hydroxyl content at the center and a quartz ring with a low hydroxyl content on the periphery. The two different qualities of quartz can be cut and applied to different fields in the later stage.

[0028] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing quartz ingots using an oxyhydrogen flame, characterized in that, The synthesis device is prepared based on a furnace body (10) and a target holder (1) that rotates and descends inside. Multiple oxyhydrogen torches (3) and plasma torches (4) are arranged above the target holder (1). The multiple oxyhydrogen torches (3) form a melting focus at the center of the target holder (1). The multiple plasma torches (4) are distributed radially along the target holder (1). The multiple oxyhydrogen torches (3) form a high-temperature melting zone (7) on the target holder (1). The multiple plasma torches (4) form a dehydroxylation zone (8) on the target holder (1). A cooling zone (9) is formed between the plasma torches (4) and the edge of the target holder (1). The preparation method includes the following steps. S1. The quartz sand raw material is heated by an oxyhydrogen torch (3) and falls into the high-temperature melting zone (7) on the target holder (1); S2. The target holder (1) rotates to make the melt move outward centrifugally, and the plasma torch (4) is used to perform high-temperature dehydroxylation treatment on the moving melt; S3. After passing through the dehydroxylation zone (8), the melt enters the cooling zone (9) for cooling; S4. The target holder (1) rotates and descends while the melt is dehydroxylated layer by layer to form a quartz ingot (2).

2. The method for preparing quartz ingots using an oxyhydrogen flame according to claim 1, characterized in that: Multiple protective gas pipes (5) are provided between the hydrogen-oxygen torch (3) and the plasma torch (4). The protective gas pipes (5) are arranged around the hydrogen-oxygen torch (3). A gap is provided between the protective gas pipes (5) and the hydrogen-oxygen torch (3) to form an exhaust channel. The top of the furnace body (10) is provided with an exhaust port (6) that matches the exhaust channel.

3. The method for preparing quartz ingots using an oxyhydrogen flame according to claim 2, characterized in that: The outlet of the protective air tube (5) faces the center of the target holder (1).

4. A method for preparing quartz ingots using an oxyhydrogen flame according to any one of claims 2 or 3, characterized in that: The protective gas pipe (5) emits nitrogen or helium gas.

5. The method for preparing quartz ingots using an oxyhydrogen flame according to claim 1, characterized in that: The flow rate ratio of hydrogen to oxygen in the hydrogen-oxygen torch (3) is (2-2.1):

1.

6. The method for preparing quartz ingots using an oxyhydrogen flame according to claim 1, characterized in that: The target holder (1) rotates at a constant speed of 12-15 rpm and descends at a constant speed of 0.5-1 mm / min.

7. The method for preparing quartz ingots using an oxyhydrogen flame according to claim 1, characterized in that: The pressure inside the furnace body (10) is controlled at 10-100 Pa.

8. A quartz ingot, prepared by the method of any one of claims 1-7, characterized in that: The quartz ingot has a diameter of 800 mm. The center of the quartz ingot is a high-hydroxyl cylindrical part with a hydroxyl content of 200-250 ppm, and the remainder is a low-hydroxyl cyclic part with a hydroxyl content of 2-4 ppm.

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