Ultrahigh-temperature chlorination process and device for low-hydroxyl high-purity quartz sand

Abstract

The invention discloses an ultrahigh-temperature chlorination process and device for low-hydroxyl high-purity quartz sand, the process and device can realize chlorination roasting of the quartz sand at the highest temperature of 1600 DEG C, a chlorinating agent is dry Cl2, the chlorination time is adjustable, and the problems that a traditional chlorination process and equipment for the quartz sand are short in chlorination time, low in impurity element removal efficiency, high in hydroxyl content and the like are solved. The quartz sand is subjected to high-temperature chloridizing roasting and is combined with a high-frequency ultrasonic strengthening washing process, the content of impurity elements in the quartz sand is smaller than or equal to 15 ppm, the content of hydroxyl in the quartz sand is greatly reduced (smaller than or equal to 10 ppm) compared with a traditional chloridizing process, and the quartz sand is high-quality low-hydroxyl ultra-high-purity quartz sand for quartz crucibles and high-temperature-resistant quartz glass in the photovoltaic and semiconductor industries.

Description

Technical Field

[0001] The invention belongs to the field of high-purity quartz sand material preparation, and specifically relates to an ultra-high temperature chlorination process and device for low-hydroxyl high-purity quartz sand. Background Art

[0002] High-purity quartz sand is the key raw material for quartz products such as quartz glass, quartz crucibles and quartz ceramics, and is widely used in high-tech manufacturing fields such as photovoltaics and semiconductors. The impurity content and hydroxyl content in quartz sand determine the performance of quartz products.

[0003] The impurity elements in quartz sand mainly include Fe, Al, Mg, Ca, Na, K, Ti, Li, etc. These impurities exist in the quartz raw stone in various forms such as bauxite, feldspar, mica, iron, etc., and some impurity elements also exist in the lattice of quartz crystals. The presence of these impurities, on the one hand, affects the high-temperature performance of quartz products, and at the same time, it is easy to contaminate crystalline silicon during the preparation of photovoltaic and semiconductor crystalline silicon, affecting its light conversion efficiency and semiconductor performance. On the one hand, because there are a large number of liquid phase, gas phase and other inclusions in the quartz raw stone, if they cannot be effectively removed, these inclusions are easy to produce numerous small bubbles in the quartz crucible or quartz glass during the preparation process, affecting the high-temperature performance or optical properties of these products.

[0004] At present, the purification of high-purity quartz sand generally adopts water quenching, pickling, flotation, magnetic separation and other processes to remove most of the impurities such as feldspar, mica, iron, etc. in the quartz sand, and in order to further remove the small amount of impurity elements such as Na, K, Fe, Mg, etc. remaining in the inclusions or crystals, the chlorination roasting process will be used in the end. To a certain extent, the chlorination roasting process determines the quality of the final high-purity quartz sand. At present, the chlorination roasting process mainly uses a rotating quartz glass tube as a carrier, and the quartz sand is added from the head to the tail for continuous processing. The chlorinating agent used is mainly one or two of HCl and Cl2. The gas is introduced from the tail and discharged from the head, contacts with the quartz sand, and reacts with the impurities in the quartz sand to produce chlorides of the impurity elements. These chlorides are partially discharged through the gas to achieve the effect of impurity removal.

[0005] There are five main problems in the current quartz sand chlorination roasting process: First, the roasting temperature is not enough, generally 900-1200℃, and some impurity elements are difficult to react with the chlorinating agent. In addition, the gasification temperature of some chlorides produced by the reaction, such as calcium chloride, magnesium chloride, sodium chloride, potassium chloride, etc., is relatively high, and they cannot be removed through the gas phase and remain in the quartz sand; second, the quartz sand roasting time is short, and some impurity elements are difficult to migrate to the surface of the quartz sand in time, so they cannot be removed by chlorination; third, the chlorinating agent currently used is mainly a mixture of HCl and Cl2. HCl reacts with impurity elements to generate chlorides and also produces a certain amount of water. The Cl2 used in industry also contains a certain amount of water. These waters produce a large amount of hydroxyl groups in the quartz sand at high temperatures. These hydroxyl groups are prone to produce a large amount of gas when the quartz sand is melted at high temperature, thereby generating microbubbles in the quartz crucible or quartz glass, affecting the performance of these products. Fourth, the quartz sand is a finished product of high-purity quartz sand after the chlorination process, and some chlorination products produced by chlorination roasting remain in the quartz sand, affecting the product quality. Fifth, the amount of chlorination agent used is large, and most chlorination gas usage exceeds 5L / kg, and some reach 9L / kg (ZL 202411248549.2). The use of a large amount of chlorination agent not only increases the chlorination cost, but also increases the difficulty and cost of tail gas treatment. Summary of the invention

[0006] The first object of the present invention is to provide a high-purity quartz sand chlorination process to solve the problems of low temperature, short time, low efficiency of impurity element removal and large amount of hydroxyl groups generated in the traditional quartz sand chlorination process.

[0007] The second object of the present invention is to provide a high-purity quartz sand chlorination process equipment to provide a key guarantee for the industrialization of the preparation of low-hydroxyl ultra-high purity quartz sand.

[0008] In order to achieve the above first purpose, the technical solution adopted by the present invention is as follows: A low-hydroxyl high-purity quartz sand ultra-high temperature chlorination process comprises the following steps: (1) Put quartz sand into a quartz crucible and then send it into a closed roasting furnace; (2) Preheat the temperature in the furnace to 100-200°C, and then evacuate the gas in the furnace; (3) Continue to raise the temperature in the furnace to 1400~1600℃, and then inject dry Cl2 into the furnace for chlorination roasting; (4) After chlorination roasting for 30 to 120 minutes, stop supplying Cl2 and then evacuate the gas in the furnace; (5) The calcined quartz sand is rapidly cooled to below 50°C, washed with high-frequency ultrasonic waves, and dried to obtain the quartz sand.

[0009] Specifically, the total impurity content of the low-hydroxyl high-purity quartz sand prepared by the present invention is ≤15ppm, and the hydroxyl content is ≤10ppm, which are significantly lower than those in the prior art.

[0010] Specifically, in step (2), the quartz sand and the water in the furnace can be evaporated and discharged by preheating, thereby reducing the hydroxyl component.

[0011] Specifically, in step (3), before Cl2 enters the furnace, water is removed from it by concentrated sulfuric acid to avoid increasing the hydroxyl content of quartz sand during the high-temperature chlorination process.

[0012] Specifically, in step (3), the purity of Cl2 is not less than 99.9%, the volume ratio of Cl2 introduced to the mass of the quartz sand raw material is 0.5-2L / kg, and the flow rate of introduction is controlled at 1-10L / min. The roasting time and Cl2 concentration are freely adjusted according to the characteristics of the quartz sand entering the chlorination roasting furnace and the impurity content, which can ensure that the impurity elements are fully chlorinated and removed.

[0013] Specifically, in step (2) and step (4), the gas in the furnace is evacuated until the gas pressure in the furnace is ≤0.1 atm.

[0014] Specifically, in step (3), the calcination temperature is ultra-high temperature chlorination calcination of up to 1600°C. On the one hand, impurities in the lattice, grain boundaries and inclusions in the quartz sand can quickly migrate to the surface, thereby enhancing the reaction with Cl2; on the other hand, the high temperature can make the high-boiling point chlorides such as calcium chloride, magnesium chloride, sodium chloride and lithium chloride produced by chlorination be vaporized and discharged, thereby improving the removal rate of these impurities.

[0015] Specifically, in step (5), the calcined quartz sand is rapidly cooled to below 50° C. by air cooling, and the introduced cold air is purified.

[0016] Specifically, in step (5), the ultrasonic frequency of the high-frequency ultrasonic enhanced water washing is ≥40 Hz, and the water washing time is 5-20 minutes. Ultrasonic enhanced cleaning can not only fully remove the chlorination products that are not fully vaporized and have not reached the vaporization temperature and remain in the solid state on the quartz surface, but also remove the impurity elements in the cracks of the quartz particles.

[0017] In order to achieve the above second purpose, the technical solution adopted by the present invention is as follows: A device for ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand comprises a roasting furnace, a quartz crucible, an air distribution plate, a cover plate, an air guide pipe and a chlorine gas channel; the quartz crucible can be placed in the furnace of the roasting furnace; the air distribution plate is arranged at the bottom of the quartz crucible, one end of the chlorine gas channel passes through the bottom of the quartz crucible and is connected to the air distribution plate, and the other end is led out of the roasting furnace and connected to an external Cl2 gas supply system, so as to inject dry Cl2 into the quartz crucible; the cover plate is closed at the top opening of the quartz crucible, one end of the air guide pipe passes through the cover plate and is connected to the inside of the quartz crucible, and the other end is led out of the roasting furnace and is connected to an external exhaust system, so as to extract the waste gas in the quartz crucible and discharge it after treatment.

[0018] Furthermore, the bottom of the roasting furnace is configured as a movable base, and a track is provided below the movable base; the quartz crucible is placed on the movable base through a group of support blocks and can slide along the track direction to enter or move out of the furnace of the roasting furnace.

[0019] Furthermore, the air guide pipe and the chlorine gas channel located in the roasting furnace are both quartz tubes; the air distribution plate is a quartz plate with air distribution holes evenly opened in the middle. Beneficial Effects

[0020] (1) The present invention uses an ultra-high temperature chlorination process to efficiently remove the impurity elements that are difficult to remove in the quartz sand lattice, grain boundaries and inclusions, and avoids the problem of a substantial increase in the hydroxyl content of quartz sand treated by the traditional chlorination process, so that the quartz crucible or quartz glass prepared with the quartz sand has a low impurity content and a significantly reduced microbubble content, thereby improving the mechanical properties, optical properties and high temperature resistance of quartz products, and combining ultrasonic enhanced water washing to remove residual chlorination products and crack impurities. The quartz sand of the present invention is subjected to high temperature chlorination roasting and combined with an ultrasonic enhanced water washing process, and the impurity element content in the quartz sand is ≤15ppm, and the hydroxyl content in the quartz sand is also significantly reduced (≤10ppm) compared with the traditional chlorination process. It is a high-quality low-hydroxyl ultra-high purity quartz sand for quartz crucibles and high-temperature resistant quartz glass used in the photovoltaic and semiconductor industries, providing a key guarantee for the preparation of low-hydroxyl ultra-high purity quartz sand.

[0021] (2) The ultra-high temperature chlorination device for quartz sand of the present invention has a compact structure and can realize batch continuous roasting of quartz sand, thus providing basic conditions for the industrial production of ultra-high purity quartz sand. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0023] Figure 1It is a schematic diagram of the device structure of the ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand of the present invention.

[0024] Figure 2 This is a process flow chart of ultra-high temperature chlorination of low-hydroxyl high-purity quartz sand of the present invention.

[0025] Wherein, each reference numeral represents: 1-quartz crucible; 2-air distribution plate; 3-cover plate; 4-air guide tube; 5-support block; 6-chlorine gas channel; 7-roasting furnace; 8-track. DETAILED DESCRIPTION

[0026] The present invention can be better understood with reference to the following examples.

[0027] The device structure of the ultra-high temperature chlorination process of low hydroxyl high purity quartz sand of the present invention is as follows: Figure 1 As shown, it includes a roasting furnace 7, a quartz crucible 1, an air distribution plate 2, a cover plate 3, an air guide pipe 4 and a chlorine gas channel 6; the quartz crucible 1 can be placed in the furnace of the roasting furnace 7; the air distribution plate 2 is arranged at the bottom of the quartz crucible 1, one end of the chlorine gas channel 6 passes through the bottom of the quartz crucible 1 and is connected to the air distribution plate 2, and the other end is led out from the roasting furnace 7 and connected to the external Cl2 gas supply system, which is used to inject dry Cl2 into the quartz crucible 1; the cover plate 3 covers the top opening of the quartz crucible 1, one end of the air guide pipe 4 passes through the cover plate 3 and is connected to the inside of the quartz crucible 1, and the other end is led out from the roasting furnace 7 and connected to the external exhaust system, which is used to extract the exhaust gas in the quartz crucible 1 and discharge it after treatment.

[0028] In this embodiment, the bottom of the roasting furnace 7 is set as a movable base, and a track 8 is provided under the movable base; the quartz crucible 1 is placed on the movable base through a group of support blocks 5, and can slide along the track 8 to enter or move out of the furnace of the roasting furnace 7.

[0029] In this embodiment, the air guide pipe 4 and the chlorine gas channel 6 located in the roasting furnace 7 are both quartz tubes; the air distribution plate 2 is a quartz plate with air distribution holes evenly opened in the middle.

[0030] In this embodiment, the roasting chamber of the roasting furnace 7 is made of high-purity silicon bricks as a furnace, and its bottom can move on a track, and high-purity silicon bricks are laid on it as the lower furnace body of the roasting furnace 7.

[0031] The roasting furnace 7 has front and rear doors, and the rear door is connected to the cooling furnace body. The quartz sand carrier is a quartz crucible 1, and there is a gas pipeline under the quartz crucible 1. The pipeline can pass through the rail car and communicate with the external Cl2 gas supply system. The gas pipeline inside the furnace is a quartz glass tube. An air distribution plate 2 is laid at the bottom of the quartz crucible 1. The air distribution plate 2 is made of quartz ceramic or quartz glass. The air distribution plate 2 has air outlet holes with an aperture not exceeding 0.5 mm. There is a cover plate 3 on the quartz crucible 1, and the cover plate 3 has a quartz glass tube as an air guide 4. The gas in the crucible is discharged to the outside of the furnace through the exhaust system and enters the exhaust gas treatment device. The Cl2 gas supply system is a chlorine gas treatment and drying device, which mainly includes an absorption tower, a drying tank and a flow control system. Concentrated sulfuric acid is injected into the drying tank, and the absorption tower uses calcium hydroxide or hydroxide as a treatment agent. Before entering the roasting furnace, Cl2 passes through a drying tank to fully remove moisture from it; after being filtered out of the furnace, Cl2 enters an absorption tower for treatment.

[0032] The above device is used to prepare low-hydroxyl high-purity quartz sand. The ultra-high temperature chlorination process flow chart is shown in Figure 2 , mainly includes the following steps: (1) Put quartz sand into a quartz crucible and then send it into a closed roasting furnace; (2) Preheat the temperature in the furnace to 100-200°C, and then evacuate the gas in the furnace; (3) Continue to raise the temperature in the furnace to 1400~1600℃, and then inject dry Cl2 into the furnace for chlorination roasting; (4) After chlorination roasting for 30 to 120 minutes, stop supplying Cl2 and then evacuate the gas in the furnace; (5) The calcined quartz sand is rapidly cooled to below 50°C, and then ultrasonically enhanced washed and dried to obtain the quartz sand.

[0033] In this embodiment, the total impurity content of the prepared low-hydroxyl high-purity quartz sand is ≤15ppm, and the hydroxyl content is ≤10ppm, which is significantly lower than that in the prior art.

[0034] In step (2), the quartz sand and the water in the furnace can be evaporated and discharged by preheating, thereby reducing the hydroxyl component.

[0035] In step (3), before Cl2 enters the furnace, water is removed from it by concentrated sulfuric acid to avoid increasing the hydroxyl content of quartz sand during the high-temperature chlorination process.

[0036] In step (3), the purity of Cl2 is 99.99%, the volume ratio of Cl2 introduced to the mass of the quartz sand raw material is 0.5-2L / kg, and the flow rate of introduction is controlled at 1-10L / min. The roasting time and Cl2 concentration are freely adjusted according to the characteristics of the quartz sand entering the chlorination roasting furnace and the impurity content, which can ensure that the impurity elements are fully chlorinated and removed.

[0037] In step (2) and step (4), the gas in the furnace is evacuated until the gas pressure in the furnace is ≤0.1atm.

[0038] In step (3), the calcination temperature is ultra-high temperature chlorination calcination up to 1600°C. On the one hand, impurities in the lattice, grain boundaries and inclusions in the quartz sand can quickly migrate to the surface, thereby enhancing the reaction with Cl2; on the other hand, the high temperature can make the high-boiling point chlorides such as calcium chloride, magnesium chloride, sodium chloride and lithium chloride produced by chlorination be vaporized and discharged, thereby improving the removal rate of these impurities.

[0039] In step (5), the calcined quartz sand is quickly cooled to below 50° C. by air cooling, and the cold air introduced is purified.

[0040] In step (5), the ultrasonic frequency of the high-frequency ultrasonic enhanced water washing is ≥40 Hz, and the water washing time is 5-20 minutes. Ultrasonic enhanced cleaning can not only fully remove the chlorination products that are not fully vaporized and have not reached the vaporization temperature and remain in the solid state on the quartz surface, but also remove the impurity elements in the cracks of the quartz particles. Example 1

[0041] Add high-alumina quartz sand with a total impurity content of 45ppm (including Fe=6.432ppm, Mg=1.380ppm, Ca=0.673ppm, Al=18.920ppm, Na=1.315ppm, K=3.837ppm) into the quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1600℃, and dried Cl2 is introduced at a flow rate of 6L / min and the exhaust system is turned on. After keeping warm for 30 minutes, push the crucible to the cooling room for ventilation and cooling to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 14.2ppm (including Fe=0.043ppm, Mg=0.085ppm, Ca=0.309ppm, Al=13.865ppm, Na=0.448ppm, K=0.709ppm), and the hydroxyl content is 4.560ppm. Example 2

[0042] Add quartz sand with a total impurity content of 33.7ppm (including Fe=1.697ppm, Mg=0.732ppm, Ca=2.948ppm, Al=7.626ppm, Na=1.295ppm, K=2.580ppm) into a quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1450℃, and dried Cl2 is introduced at a flow rate of 5L / min and the exhaust system is turned on. After keeping warm for 45 minutes, push the crucible to the cooling room for ventilation and cooling to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 13ppm (including Fe=0.041ppm, Mg=0.063ppm, Ca=0.217ppm, Al=6.701ppm, Na=0.385ppm, K=0.516ppm), and the hydroxyl content is 8.022ppm. Example 3

[0043] Add high-magnesium quartz sand with a total impurity content of 38.4ppm (including Fe=2.956ppm, Mg=7.454ppm, Ca=2.328ppm, Al=13.003ppm, Na=1.074ppm, K=2.830ppm) into a quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1400℃, and dried Cl2 is introduced at 4L / min and the exhaust system is turned on. After keeping warm for 40 minutes, push the crucible to the cooling room for cold ventilation to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 13ppm (including Fe=0.042ppm, Mg=0.082ppm, Ca=0.656ppm, Al=11.722ppm, Na=0.467ppm, K=0.628ppm), and the hydroxyl content is 8.423ppm. Comparative Example 1

[0044] Add high-alumina quartz sand with a total impurity content of 45ppm (including Fe=6.432ppm, Mg=1.380ppm, Ca=0.673ppm, Al=18.920ppm, Na=1.315ppm, K=3.837ppm) into a quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1600℃, and dry Cl2 and HCl at a flow rate of 3L / min and 3L / min are simultaneously introduced into the roasting furnace and the exhaust system is turned on. After keeping warm for 30 minutes, push the crucible to the cooling room and cool it to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 17.2ppm (including Fe=0.048ppm, Mg=0.090ppm, Ca=0.333ppm, Al=14.312ppm, Na=0.442ppm, K=0.705ppm), and the hydroxyl content is 26.445ppm. Comparative Example 2

[0045] Add high-alumina quartz sand with a total impurity content of 45ppm (including Fe=6.432ppm, Mg=1.380ppm, Ca=0.673ppm, Al=18.920ppm, Na=1.315ppm, K=3.837ppm) into the quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1200℃, and dried Cl2 is introduced at a flow rate of 6L / min and the exhaust system is turned on. After keeping warm for 60min, push the crucible to the cooling room and cool it to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 22.3ppm (including Fe=0.065ppm, Mg=0.094ppm, Ca=0.421ppm, Al=16.679ppm, Na=0.472ppm, K=0.729ppm), and the hydroxyl content is 8.650ppm. Comparative Example 3

[0046] Add high-alumina quartz sand with a total impurity content of 45ppm (including Fe=6.432ppm, Mg=1.380ppm, Ca=0.673ppm, Al=18.920ppm, Na=1.315ppm, K=3.837ppm) into the quartz crucible. The thickness of the quartz sand in the quartz crucible is about 30cm. Place the crucible in a chlorination roasting furnace and connect the gas pipeline. The roasting furnace is quickly heated to 1600℃, and undried Cl2 is introduced at a flow rate of 6L / min and the exhaust system is turned on. After keeping warm for 30 minutes, push the crucible to the cooling room and cool it to below 50℃ and take it out. After 40Hz ultrasonic enhanced water washing, the impurity content in the quartz sand is 15.7ppm (including Fe=0.046ppm, Mg=0.082ppm, Ca=0.337ppm, Al=15.755ppm, Na=0.462ppm, K=0.770ppm), and the hydroxyl content is 9.703ppm.

[0047] The present invention provides a low-hydroxyl high-purity quartz sand ultra-high temperature chlorination process and device idea and method. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A low-hydroxyl high-purity quartz sand ultra-high temperature chlorination process, characterized in that: The steps include: (1) Put quartz sand into a quartz crucible and then send it into a closed roasting furnace; (2) Preheat the temperature in the furnace to 100-200°C, and then evacuate the gas in the furnace; (3) Continue to raise the temperature in the furnace to 1400~1600℃, and then inject dry Cl2 into the furnace for chlorination roasting; (4) After chlorination roasting for 30 to 120 minutes, stop supplying Cl2 and then evacuate the gas in the furnace; (5) The calcined quartz sand is rapidly cooled to below 50°C, washed with high-frequency ultrasonic waves, and dried to obtain the quartz sand.

2. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: The total impurity content of the prepared low-hydroxyl high-purity quartz sand is ≤15ppm, and the hydroxyl content is ≤10ppm.

3. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: In step (3), the water in Cl2 is removed by concentrated sulfuric acid before entering the furnace.

4. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: In step (3), the purity of Cl2 is not less than 99.9 vt%, the volume ratio of Cl2 introduced to the mass ratio of quartz sand raw material is 0.5-2 L / kg, and the flow rate of Cl2 introduced is controlled at 1-10 L / min.

5. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: In step (2) and step (4), the gas in the furnace is evacuated until the gas pressure in the furnace is ≤0.1atm.

6. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: In step (5), the calcined quartz sand is rapidly cooled to below 50° C. by air cooling, and the cold air introduced is purified.

7. The ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 1, characterized in that: In step (5), the ultrasonic frequency of the high-frequency ultrasonic enhanced water washing is ≥40KHz, and the water washing time is 5-20min.

8. A device for ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand, characterized in that: The invention comprises a roasting furnace (7), a quartz crucible (1), an air distribution plate (2), a cover plate (3), an air guide pipe (4) and a chlorine gas channel (6); the quartz crucible (1) can be placed in the furnace of the roasting furnace (7); the air distribution plate (2) is arranged at the bottom of the quartz crucible (1); one end of the chlorine gas channel (6) passes through the bottom of the quartz crucible (1) and is connected to the air distribution plate (2); the other end is led out of the roasting furnace (7) and is connected to an external Cl2 gas supply system, and is used to inject dry Cl2 into the quartz crucible (1); the cover plate (3) covers the top opening of the quartz crucible (1); one end of the air guide pipe (4) passes through the cover plate (3) and is connected to the inside of the quartz crucible (1); the other end is led out of the roasting furnace (7) and is connected to an external exhaust system, and is used to extract the waste gas in the quartz crucible (1) and discharge it to the outside after treatment.

9. The device for ultrahigh temperature chlorination process of low hydroxyl high purity quartz sand according to claim 8, characterized in that: The bottom of the roasting furnace (7) is arranged as a movable base, and a track (8) is arranged below the movable base; the quartz crucible (1) is placed on the movable base via a set of support blocks (5) and can slide along the track (8) to enter or move out of the furnace of the roasting furnace (7).

10. The device for ultra-high temperature chlorination process of low-hydroxyl high-purity quartz sand according to claim 8, characterized in that: The air guide pipe (4) and the chlorine gas channel (6) located in the roasting furnace (7) are both quartz tubes; the air distribution plate (2) is a quartz plate with air distribution holes evenly opened in the middle.

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