Method and device for removing gas-liquid inclusion in quartz sand

Abstract

The invention discloses a method and a device for removing gas-liquid inclusion in quartz sand, the device comprises: an outer cylinder, the axis of which forms an included angle greater than 0 degree with the horizontal plane; the feeding pipe is arranged in the outer cylinder body in a penetrating manner, and the axis of the feeding pipe is parallel to the axis of the outer cylinder body; the inner cylinder body is positioned between the outer cylinder body and the feeding pipe, and the inner cylinder body is arranged outside the feeding pipe in a sleeving manner; a liquid nitrogen inlet is formed in the inner barrel; a microwave generator is arranged on the inner wall of the outer barrel, and microwave energy generated by the microwave generator radiates from the outer barrel to the feeding pipe. The microwave generator is arranged on the inner wall of the outer barrel, the liquid nitrogen inlet is formed in the inner barrel, microwave heating and liquid nitrogen cooling are combined, more gas-liquid inclusions are promoted to burst, the gas-liquid inclusions in quartz sand are effectively removed, and therefore the high-purity quartz sand needed by the semiconductor product industry and other industries is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity quartz sand purification, and particularly to a method and device for removing gas-liquid inclusions in quartz sand. Background Art

[0002] High-purity quartz sand is closely related to new-generation information technology, new materials industry and other strategic emerging industries in China. It has the characteristics of high temperature resistance, corrosion resistance, high hardness, stable chemical properties and strong light transmittance. Quartz products such as quartz glass, quartz crucibles, and quartz tubes produced therefrom are important supporting raw materials for the silicon-based strategic emerging industries.

[0003] The main raw material of high-purity quartz sand is crystal resources. With the gradual depletion of crystal resources, low-quality quartz ore has gradually become the main raw material of high-purity quartz sand. At present, the resources of high-purity quartz deposits for photovoltaic use are scarce and are mainly monopolized by enterprises such as Unimin in the United States and TQC in Norway. China is a large consumer of high-purity quartz, but there are many fluid inclusion impurities and poor ore quality in domestic quartz ore sources. There are many gas-liquid inclusions that are difficult to remove by conventional beneficiation processes, which seriously affect the quality and service life of quartz products and cannot meet the purity requirements of the semiconductor industry for high-purity quartz sand. High-end products rely heavily on imports, which is a severe challenge currently faced by China's high-purity quartz sand industry.

[0004] Gas-liquid inclusions are gas-liquid-containing fluids that accompany the crystallization and growth of minerals. These inclusions trapped in mineral crystals are sealed in the host mineral and have a phase boundary with the host mineral. Gas-liquid inclusions are generally present in domestic quartz ore, and their size ranges from 2 to 50 µm. Some trace impurity elements such as Ca, Mg, and Na are present in the quartz particle inclusions. Common impurity removal processes include crushing and screening, magnetic separation, flotation, roasting and water quenching, acid leaching, chlorination roasting, etc. The ability to remove internal inclusions in quartz is limited, which severely restricts the high-quality development of domestic high-purity quartz sand. Summary of the Invention

[0005] Aiming at the above deficiencies, the purpose of the present invention is to provide a method and device for removing gas-liquid inclusions in quartz sand to solve the technical problem that it is difficult to remove gas-liquid inclusion impurities inside quartz sand by existing processes.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions: In the first aspect, the present invention provides a device for removing gas-liquid inclusions in quartz sand, and the device includes: An outer cylinder, and an angle greater than 0° is provided between the axis of the outer cylinder and the horizontal plane; A feed pipe, the feed pipe penetrates through the inside of the outer cylinder, and the axis of the feed pipe is parallel to the axis of the outer cylinder; The inner cylinder is located between the outer cylinder and the feed pipe, and the inner cylinder is sleeved outside the feed pipe. The liquid nitrogen inlet is arranged on the inner cylinder. The microwave generator is arranged on the inner wall of the outer cylinder, and the microwave energy generated by the microwave generator radiates from the outer cylinder towards the feed pipe.

[0007] Preferably, the liquid nitrogen inlet is arranged at one end away from the feed port of the feed pipe, and the liquid nitrogen inlet includes a switching valve for controlling the introduction of liquid nitrogen.

[0008] Preferably, the above device further includes a liquid nitrogen pressure reducing valve, and the liquid nitrogen pressure reducing valve is arranged at one end of the inner cylinder away from the liquid nitrogen inlet.

[0009] Preferably, the feed pipe is a spiral pipe or a serpentine pipe.

[0010] Preferably, the included angle between the axis of the outer cylinder and the horizontal plane is 5 - 30°.

[0011] Preferably, the above device further includes an acid quenching unit, and the acid quenching unit is communicated with the discharge port of the feed pipe.

[0012] In a second aspect, the present invention also provides a method for removing gas-liquid inclusions in quartz sand, which is implemented by using the device described in the first aspect, and includes the following steps: Perform pretreatment on the quartz sand to obtain pretreated quartz sand. Feed the pretreated quartz sand into the feed pipe, and introduce liquid nitrogen into the inner cylinder through the liquid nitrogen inlet. Adjust the microwave power of the microwave generator and the inclination angle of the outer cylinder, and perform microwave heating-liquid nitrogen cooling treatment on the pretreated quartz sand to obtain high-purity quartz sand.

[0013] Preferably, adjust the microwave power of the microwave generator to 10 - 30 kW.

[0014] Preferably, adjust the inclination angle of the outer cylinder until the residence time of the pretreated quartz sand in the feed pipe is 5 - 15 min.

[0015] Preferably, the above method further includes introducing the quartz sand after microwave heating-liquid nitrogen cooling treatment into the acid quenching unit for acid quenching treatment to obtain high-purity quartz sand.

[0016] The beneficial effects of the present invention are: 1. By arranging a microwave generator on the inner wall of the outer cylinder and a liquid nitrogen inlet on the inner cylinder, the present invention enables the quartz sand to be selectively heated by microwave radiation during the process of passing through the feed pipe. At the same time, the liquid nitrogen introduced into the inner cylinder can ensure that there is a large temperature difference and pressure difference for the gas-liquid inclusions in the microwave environment. Through the combination of microwave heating and liquid nitrogen cooling, more gas-liquid inclusions are promoted to burst, thereby effectively removing the gas-liquid inclusions inside the quartz sand.

[0017] 2. The device provided by the present invention combines microwave radiation with liquid nitrogen cooling, simplifies and optimizes the process flow for removing gas-liquid inclusions inside quartz sand, avoids repeated operations of microwave radiation and liquid nitrogen cooling, saves time cost, improves production efficiency, and makes the removal of gas-liquid inclusions more convenient, environmentally friendly, and energy-efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly introduced below.

[0019] Figure 1 It is a schematic diagram of a device for removing gas-liquid inclusions in quartz sand according to an embodiment of the present invention; In the figure, 1. Outer cylinder; 2. Feed pipe; 21. Feed inlet; 22. Discharge outlet; 23. Bearing connection; 3. Inner cylinder; 31. Liquid nitrogen inlet; 32. Liquid nitrogen pressure reducing valve; 4. Microwave generator; 5. Acid quenching unit; 6. Liquid nitrogen switch valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] Conventional ore dressing methods can effectively remove gangue minerals and surface impurities in quartz sand, but it is difficult to remove gas-liquid inclusion impurities inside quartz sand, and it cannot meet the requirements of semiconductor products for high-purity quartz sand, seriously restricting the development of strategic emerging industries such as quartz glass and optical fibers. Aiming at the technical difficulty that the purity of existing high-purity quartz sand after purification is insufficient to meet the requirements of semiconductor products, the purpose of the present invention is to propose a method and device for removing gas-liquid inclusions in quartz sand by microwave-liquid nitrogen cooling, significantly improving the removal rate of gas-liquid inclusions, and the prepared high-purity quartz sand meets the requirements of semiconductor products.

[0022] In the first aspect, please refer to Figure 1, an embodiment of the present application provides a device for removing gas-liquid inclusions in quartz sand, including: an outer cylinder 1, a feed pipe 2, an inner cylinder 3, a microwave generator 4, a liquid nitrogen inlet 31, and a liquid nitrogen switch valve 6. There is an angle greater than 0° between the axis of the outer cylinder 1 and the horizontal line, preferably 5-30°. By setting it obliquely, the quartz sand can freely fall from the feeding place to the discharging place by its own gravity. The feed pipe 2 penetrates inside the outer cylinder 1, and the axis of the feed pipe 2 is parallel to the axis of the outer cylinder 1. The feed port 21 of the feed pipe 2 is located at the top (high end) of the feed pipe 2, and the discharge port 22 is located at the bottom (low end) of the feed pipe 2, so that the quartz sand continuously falls in the feed pipe 2, feeding from the feed port 21 and discharging from the discharge port 22. The feed pipe 2 is a spiral pipe or a serpentine pipe to increase the contact area between the quartz sand particles and the feed pipe 2 and extend the microwave radiation time. The microwave generator 4 is arranged on the inner wall of the outer cylinder 1 for generating microwave energy, and the generated microwave energy is radiated from the outer cylinder towards the feed pipe direction, thereby microwave heating the quartz particles in the feed pipe 2.

[0023] To avoid the quartz particles being heated up by heat conduction and ensure a large temperature difference and thermal stress in the gas-liquid inclusions of the quartz sand particles in the microwave environment, an inner cylinder 3 is sleeved outside the feed pipe 2, and the inner cylinder 3 is located between the outer cylinder 1 and the feed pipe 2. A liquid nitrogen inlet 31 is provided at one end of the inner cylinder 3 away from the feed port 21 of the feed pipe 2, that is, the liquid nitrogen inlet 31 is provided at the bottom (low end) of the inner cylinder 3. A liquid nitrogen pressure reducing valve 32 is provided at one end of the inner cylinder 3 away from the liquid nitrogen inlet 31, that is, the liquid nitrogen pressure reducing valve 32 is provided at the top (high end) of the inner cylinder 3. The inner cylinder 3 serves as a liquid nitrogen channel. Liquid nitrogen is fed in from the liquid nitrogen inlet 31 until the liquid level height exceeds the bottom of the feed pipe 2 to ensure that the quartz sand in the feed pipe 2 can be fully cooled in the liquid nitrogen environment. By controlling the gap between the valve core and the valve seat of the liquid nitrogen pressure reducing valve 32, the flow rate of liquid nitrogen and the pressure in the inner cylinder 3 are controlled. Liquid nitrogen continuously flows from the low end (right end) to the high end (left end), and the temperature can be as low as -196 °C, which can maximize the temperature difference inside and outside the gas-liquid inclusions. Increasing the contact area and time with the quartz sand particles in the microwave environment of the feed pipe 2 avoids the overall heating of the quartz particles caused by heat conduction, ensures that the outside of the quartz sand particles is maintained at a lower temperature, while the temperature of the internal gas-liquid inclusions is higher, thereby ensuring a large temperature difference and pressure difference inside and outside the quartz sand, promoting more gas-liquid inclusions to burst, establishing a discharge channel for the impurities of the gas-liquid inclusions inside the quartz particles, and effectively removing the gas-liquid inclusions in the quartz sand particles.

[0024] The above device further includes an acid quenching unit 5. The acid quenching unit 5 is an acid quenching pool, which is arranged below the discharge port 22 of the feed pipe 2. The quartz sand after microwave heating-liquid nitrogen cooling treatment falls into the acid quenching unit for acid quenching, and then high-purity quartz sand after removing gas-liquid inclusions can be obtained.

[0025] Second aspect, an embodiment of the present application provides a method for removing gas-liquid inclusions in quartz sand. The method is implemented by using the device described in the first aspect, and includes the following steps: (1) Pretreat the quartz sand to obtain pretreated quartz sand.

[0026] (2) Feed the pretreated quartz sand into the feed pipe 2 through the feed port 21, and introduce liquid nitrogen into the inner cylinder 3 through the liquid nitrogen inlet 31. Adjust the microwave power of the microwave generator to 10 - 30 kW. Due to the selectivity, instantaneity, and high efficiency of microwave radiation itself, the gas-liquid inclusion impurities can be rapidly heated to 600 °C - 1000 °C through their own dielectric loss, and adjust the inclination angle of the outer cylinder 3 until the residence time of the pretreated quartz sand in the feed pipe 2 is 5 - 15 min. The pretreated quartz sand rolls down in the feed pipe 2 under its own gravity and undergoes microwave heating - liquid nitrogen cooling treatment, and then discharges from the discharge port 22.

[0027] (3) The quartz sand discharged from the discharge port 22 falls into the ultrapure hydrochloric acid in the acid quenching unit 5 for acid quenching treatment, and then is washed twice with ultrapure water and dried to obtain high-purity quartz sand.

[0028] In step (1), the quartz raw ore is pretreated by using traditional quartz sand purification techniques, including: crushing and screening, magnetic separation, flotation, and acid leaching operations. Specifically: use a jaw crusher for coarse crushing and medium crushing respectively; the crushed minerals enter a roll crusher and screening machine for fine crushing, and the large particle lumps are recycled for crushing. After crushing, the sample enters the screening machine to select quartz sand particles with a mesh size of 60 - 160; use a periodic pulsating high-gradient magnetic separator to perform high-gradient magnetic separation and impurity removal on the quartz sand to be selected. After magnetic separation, the quartz sand is subjected to scrubbing and flotation operations using a flotation machine, and the scrubbed quartz sand is subjected to flotation and impurity removal until no impurity particles float out. After the flotation is completed, two de-drug treatments are carried out; use a reaction kettle to perform acid leaching operations on the flotation-treated quartz sand, and the leached quartz sand is washed and dried with ultrapure water to obtain pretreated quartz sand with relatively low impurity and gas-liquid inclusion content. The above traditional quartz sand purification process can be changed in sequence and the operation process can be added or subtracted according to the actual situation.

[0029] The principle of the present invention is as follows: The dielectric constant of quartz is 3.8 - 4.1 and it is usually not heated in a microwave field. The dielectric constant of water is 78.3 and it can be rapidly heated in a microwave radiation field. According to the difference in dielectric constants between quartz and water, microwave radiation can selectively heat the gas-liquid inclusion impurities with a high dielectric constant, and the temperature difference formed can reach 1000 °C or above. The water molecules rub against each other. As the temperature continues to rise, the pressure inside the inclusion increases, and the thermal stress generated is sufficient to cause cracks at the interface of the gas-liquid inclusion impurities, thereby effectively opening the gas-liquid inclusions and establishing a discharge channel for the internal inclusion impurities. In addition, the continuously flowing liquid nitrogen in the microwave field can synchronously cool the surface of the quartz sand treated by microwave radiation, keeping the outside of the quartz sand particles at a low temperature continuously. While the temperature of the gas-liquid inclusions inside the quartz sand particles is relatively high, resulting in an increased temperature difference between the inside and outside, promoting more fine gas-liquid inclusions to be cracked by thermal stress and generating cracks, thereby effectively removing more inclusion impurities inside the quartz sand and improving the purity of the quartz sand particles.

[0030] The device of the present invention provides a low-temperature microwave system with a large temperature difference between the inside and outside of the quartz sand particles and easy cracking of inclusions, which can efficiently remove gas-liquid inclusions in quartz sand under the conditions of pollution-free and low energy consumption.

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0032] Example 1 A method for removing gas-liquid inclusions in quartz sand uses the Figure 1 shown device. Among them, the outer cylinder 1 is a cylindrical sealed cavity made of metal material, the feed pipe 2 is a serpentine quartz glass pipe, and the microwave generator 4 is a plurality of strip-shaped microwave sources. The specific steps are as follows: (1) Pretreat the vein quartz ore using traditional quartz sand purification techniques, including: crushing and screening, magnetic separation, flotation, and acid leaching operations to obtain pretreated quartz sand.

[0033] (2) Feed the pretreated quartz sand into the feed pipe 2 through the feed port 21, and introduce liquid nitrogen into the inner cylinder 3 through the liquid nitrogen inlet 31. Adjust the microwave power of the microwave generator to 10 kW, and adjust the inclination angle of the outer cylinder 3 until the residence time of the pretreated quartz sand in the feed pipe 2 is 5 min. During the process of the pretreated quartz sand rolling down in the feed pipe 2 by its own gravity, it undergoes microwave heating - liquid nitrogen cooling treatment, and then discharges from the discharge port 22.

[0034] (3) The quartz sand particles discharged from the discharge port 22 fall into the ultrapure hydrochloric acid in the acid quenching unit 5 for acid quenching treatment, and after being washed twice with ultrapure water, they are placed in an oven at 80 °C and dried for 5 h to obtain high-purity quartz sand.

[0035] Example 2 A method for removing gas-liquid inclusions in quartz sand uses the Figure 1 device shown. Among them, the outer cylinder 1 is a cylindrical sealed cavity made of metal material, the feed pipe 2 is a serpentine quartz glass pipe, and the microwave generator 4 is a plurality of strip-shaped microwave sources. The specific steps are as follows: (1) Pretreat the vein quartz ore by using traditional quartz sand purification techniques, including: crushing and screening, magnetic separation, flotation, and acid leaching operations to obtain pretreated quartz sand.

[0036] (2) Feed the pretreated quartz sand into the feed pipe 2 through the feed port 21, and introduce liquid nitrogen into the inner cylinder 3 through the liquid nitrogen inlet 31. Adjust the microwave power of the microwave generator to 20 kW, and adjust the inclination angle of the outer cylinder 3 until the residence time of the pretreated quartz sand in the feed pipe 2 is 5 minutes. During the process of the pretreated quartz sand rolling down in the feed pipe 2 by its own gravity, it undergoes microwave heating-liquid nitrogen cooling treatment, and then discharges from the discharge port 22.

[0037] (3) The quartz sand particles discharged from the discharge port 22 fall into the ultrapure hydrochloric acid in the acid quenching unit 5 for acid quenching treatment, and after being washed twice with ultrapure water, they are placed in an oven at 80 °C and dried for 5 hours to obtain high-purity quartz sand.

[0038] Example 3 A method for removing gas-liquid inclusions in quartz sand uses the Figure 1 device shown. Among them, the outer cylinder 1 is a cylindrical sealed cavity made of metal material, the feed pipe 2 is a serpentine quartz glass pipe, and the microwave generator 4 is a plurality of strip-shaped microwave sources. The specific steps are as follows: (1) Pretreat the vein quartz ore by using traditional quartz sand purification techniques, including: crushing and screening, magnetic separation, flotation, and acid leaching operations to obtain pretreated quartz sand.

[0039] (2) Feed the pretreated quartz sand into the feed pipe 2 through the feed port 21, and introduce liquid nitrogen into the inner cylinder 3 through the liquid nitrogen inlet 31. Adjust the microwave power of the microwave generator to 20 kW, and adjust the inclination angle of the outer cylinder 3 until the residence time of the pretreated quartz sand in the feed pipe 2 is 10 minutes. During the process of the pretreated quartz sand rolling down in the feed pipe 2 by its own gravity, it undergoes microwave heating-liquid nitrogen cooling treatment, and then discharges from the discharge port 22.

[0040] (3) The quartz sand particles discharged from the discharge port 22 fall into the ultrapure hydrochloric acid in the acid quenching unit 5 for acid quenching treatment, and after being washed twice with ultrapure water, they are placed in an oven at 80 °C and dried for 5 hours to obtain high-purity quartz sand.

[0041] Comparative Example 1 The raw quartz ore is purified by using traditional quartz sand purification technology, including: crushing and screening, magnetic separation, flotation, and acid leaching operations, to obtain quartz sand particles purified by the traditional process.

[0042] Take the quartz sand particles purified in Examples 1 to 3 and Comparative Example 1 respectively on a glass slide, drop an appropriate amount of clove oil, cover with a cover glass, and then observe under a polarized light microscope. Observe the internal impurity content of the quartz sand through a polarized light microscope, and the results are shown in Table 1.

[0043] Table 1 Detection results of the number of microscopic inclusions in the products of Examples and Comparative Examples

[0044] As can be seen from Table 1, the traditional process does not establish a discharge channel for gas-liquid inclusions, and there are still many gas-liquid inclusion impurities remaining, indicating that the traditional purification method cannot completely remove gas-liquid inclusions. Compared with the high-temperature heating condition, the quartz sand after microwave radiation and then acid quenching proposed in the present invention can form a greater thermal stress and pressure difference through the continuously flowing liquid nitrogen and the instantaneous microwave of the internal gas-liquid inclusions, and can burst the gas-liquid inclusions inside the quartz sand particles with lower energy consumption and high efficiency, and then through acid quenching, so as to better remove the gas-liquid inclusions on the surface and inside of the quartz sand.

[0045] It should be noted that the above embodiments all belong to the same inventive concept. The descriptions of the embodiments have their own emphases. For the parts not described in detail in individual embodiments, reference can be made to the descriptions in other embodiments.

[0046] The above embodiments only express the implementation manners of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An apparatus for removing gas-liquid inclusions in quartz sand, characterized in that, Comprising: An outer cylinder, wherein there is an angle greater than 0° between the axis of the outer cylinder and the horizontal plane; A feed pipe, which penetrates inside the outer cylinder, and the axis of the feed pipe is parallel to the axis of the outer cylinder; An inner cylinder, which is located between the outer cylinder and the feed pipe, and the inner cylinder is sleeved outside the feed pipe; A liquid nitrogen inlet, which is arranged on the inner cylinder; A microwave generator, which is arranged on the inner wall of the outer cylinder, and the microwave energy generated by the microwave generator radiates from the outer cylinder towards the feed pipe; 2. The device for removing gas-liquid inclusions in quartz sand according to claim 1, characterized in that, The liquid nitrogen inlet is arranged at one end away from the feed port of the feed pipe.

3. The device for removing gas-liquid inclusions in quartz sand according to claim 1, characterized in that, It further includes a liquid nitrogen pressure reducing valve, which is arranged at one end of the inner cylinder away from the liquid nitrogen inlet.

4. The device for removing gas-liquid inclusions in quartz sand according to claim 1, wherein, The feed pipe is a spiral pipe or a serpentine pipe.

5. The device for removing gas-liquid inclusions in quartz sand according to claim 1, characterized in that, The angle between the axis of the outer cylinder and the horizontal plane is 5 - 30°.

6. The device for removing gas-liquid inclusions in quartz sand according to claim 1, characterized in that, It further includes an acid quenching unit, which is communicated with the discharge port of the feed pipe.

7. A method for removing gas-liquid inclusions in quartz sand, characterized in that, Implementing by using the device for removing gas-liquid inclusions in quartz sand according to any one of claims 1 - 6, including the following steps: Pre-treating the quartz sand to obtain pre-treated quartz sand; Feeding the pre-treated quartz sand into the feed pipe, and introducing liquid nitrogen into the inner cylinder through the liquid nitrogen inlet, adjusting the microwave power of the microwave generator and the inclination angle of the outer cylinder, and performing microwave heating - liquid nitrogen cooling treatment on the pre-treated quartz sand to obtain high-purity quartz sand.

8. The method for removing gas-liquid inclusions in quartz sand according to claim 7, characterized in that, Adjusting the microwave power of the microwave generator to 10 - 30 kW.

9. The method for removing gas-liquid inclusions in quartz sand according to claim 7, characterized in that, Adjusting the inclination angle of the outer cylinder until the residence time of the pre-treated quartz sand in the feed pipe is 5 - 15 min.

10. The method for removing gas-liquid inclusions in quartz sand according to claim 7, characterized in that, It further includes introducing the quartz sand after microwave heating - liquid nitrogen cooling treatment into the acid quenching unit for acid quenching treatment to obtain the high-purity quartz sand.

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