Method and equipment for purifying high-purity quartz sand from granite pegmatite

Abstract

The present invention discloses a method and apparatus for purifying high-purity quartz sand from granite pegmatite. The process of the present invention can deeply remove impurities from quartz sand concentrate made from granite pegmatite, effectively removing both fluid inclusion impurities and lattice impurities, which are difficult to remove in quartz. The process is particularly effective in removing interstitial ions such as alkali metals, and also has a certain degree of removal effect on stubborn impurity elements such as aluminum and titanium. This method can enable the purity of high-purity quartz sand to break through the bottleneck of 5N. The present invention has the advantages of simple operation, a short process, and good impurity removal effect.

Description

Technical Field

[0001] The invention belongs to the technical field of quartz sand purification, and particularly relates to a method and equipment for purifying high-purity quartz sand from granite pegmatite. Background Art

[0002] High-purity quartz sand plays a vital role in many high-tech industries due to its unique physical and chemical properties. Currently, the raw materials for high-purity quartz sand suitable for industrial mass production mainly include vein quartz and granite pegmatite. Granite pegmatite quartz is formed by the slow crystallization of high-temperature magma. Due to the high magma temperature and long cooling time, impurities in the quartz system are easily precipitated. As a result, the quartz in granite pegmatite, a magmatic rock, is extremely pure and contains very few gas-liquid inclusions. Although the quartz content in granite pegmatite is only about 30%, the quartz grains are extremely coarse (d>5mm), completely dissociated from the gangue after grinding, and the impurity content of individual quartz is extremely low, making it an ideal raw material for processing high-purity quartz into mid- to high-end products.

[0003] Impurities in granite pegmatite ore can be divided into three categories based on their size, distribution, and formation characteristics: gangue mineral impurities, inclusion impurities, and crystal structure impurities. While existing high-purity quartz purification processes have achieved near-perfect removal of gangue mineral impurities, inclusion impurities and crystal structure impurities are the main impurities that hinder further improvement in the purity of high-purity quartz sand. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method and equipment for purifying high-purity quartz sand from granite pegmatite.

[0005] The method for purifying high-purity quartz sand from granite pegmatite of the present invention comprises the following steps:

[0006] S1. The quartz sand concentrate is fed into the furnace tube of the purification equipment, the quartz sand is heated by microwave heating, chlorinated gas is introduced into the furnace tube under vacuum, and then maintained at the crystal transition temperature of the quartz and the pressure in the furnace chamber is repeatedly switched between positive and negative pressures;

[0007] S2 continues to heat to the final chlorination temperature and heat, during which the pressure in the furnace chamber is repeatedly switched between positive and negative pressures; after the insulation is completed, the temperature is naturally cooled to room temperature;

[0008] During the reaction process of steps S1 and S2, the furnace tube is always kept rotating. The rotation of the furnace tube and the disturbance of the lines on the inner wall of the furnace tube are used to promote full contact between the quartz sand concentrate and the chlorination gas, thereby improving the reaction efficiency.

[0009] The crystal transition temperature of S1 is 573° C., and maintaining the crystal transition temperature of quartz means keeping the temperature at 573° C. for 10 min-1 h.

[0010] The final chlorination temperature in S2 refers to 1000°C-1500°C, and continuing to heat to the final chlorination temperature and keeping it warm refers to heating to 1000°C-1500°C and keeping it warm for 60min-240min.

[0011] The repeated switching of the gas pressure in the furnace cavity between positive and negative pressures means that the gas pressure in the furnace cavity is repeatedly switched between -0.4 MPa and 0.1 MPa.

[0012] The chlorinated gas is chlorine gas, hydrogen chloride gas or a mixed gas of the two, and the ratio of the mixed gas is chlorine gas: hydrogen chloride = 1: (0.1-10).

[0013] The volume ratio of the filling amount of the quartz sand concentrate to the furnace cavity of the roasting furnace is (0.5-5):10, and the rotation speed of the furnace tube is 1-10rmp / min.

[0014] The dielectric constant difference between the fluid inclusions and the quartz matrix is ​​large. In a microwave field, the inclusions quickly absorb electromagnetic waves and heat up rapidly, thereby generating a large temperature difference between them and the quartz matrix, prompting the inclusions to thermally crack and produce microcracks, creating favorable conditions for the chlorination reaction. Simultaneously, during the roasting and heating process, the quartz crystal undergoes a crystal phase transformation, accompanied by changes in the lattice volume, which further promotes the migration and chlorination of lattice impurities. Therefore, the microwave chlorination process can simultaneously reduce the content of inclusion impurities and lattice impurities, further improving the purity of high-purity quartz sand. The present invention has the advantages of simple operation, short process, and good impurity removal effect.

[0015] The device for purifying high-purity quartz sand from granite pegmatite of the present invention comprises: a microwave main body, which is installed on a base; a furnace tube, which is installed in the microwave main body, is spindle-shaped, and has two ends connected to an air inlet pipe and an air outlet pipe respectively; a chlorination gas generator, which is located inside the base and connected to the air inlet pipe; a micro vacuum pump, which is located inside the base and connected to the air outlet pipe; a drive assembly, which is located above the base and connected to the air inlet pipe; a rotating support, which is located above the base and rotatably connected to the air inlet pipe and the air outlet pipe respectively; a microwave generator, which is located inside the base and connected to the microwave main body; and a sampler, which is spoon-shaped.

[0016] The two ends of the furnace tube are respectively connected to the air inlet pipe and the air outlet pipe through flanges. The air inlet pipe and the air outlet pipe are both connected to the bearing seat. The bottom of the bearing seat is connected to the fixed support through a vibrator. The fixed support is located above the base. The ends of the two bearing seats away from the furnace tube are the feed port and the discharge port respectively. The air inlet is set on the bearing seat close to the feed port, and the air outlet is set on the bearing seat close to the discharge port.

[0017] The inner wall of the furnace tube is provided with discontinuous and staggered spiral convex strips extending from the midpoint to both ends, and the midpoint of the furnace tube is recessed outwards to form a collecting groove.

[0018] The sampler includes a handle and a spoon body. The width and height of the spoon body are smaller than the inner diameter of the openings at both ends of the furnace tube. Release paper is placed inside the spoon body. The length and width of the spoon body are larger than the length and width of the collection tank.

[0019] The beneficial effects of the present invention are as follows: the present invention uses granite pegmatite with a small number of inclusions and a low impurity content as raw material, and carries out deep impurity removal on the basis of quartz sand concentrate; microwave heating is used, and due to the large difference in dielectric constants between fluid inclusions and the quartz matrix, the inclusions absorb heat rapidly, causing microcracks or even thermal explosions, exposing impurities; during the heating process, the quartz crystal transformation temperature is kept at a temperature for a period of time, and the displacement transformation of the quartz crystal is used to promote the exposure of more impurities; the air pressure oscillation method is used to repeatedly switch the air pressure between positive and negative pressures during the insulation process, thereby promoting the rupture of more inclusions; a rotatable furnace tube with an uneven inner wall is used to greatly increase the reaction area between quartz sand and chlorinated gas; experimental results show that the present invention has a good removal effect on inclusion impurities and lattice impurities that are difficult to remove in quartz, especially the best removal effect on interstitial ions such as alkali metals, and also has a certain removal effect on stubborn impurity elements such as aluminum and titanium, which can further improve the purity of high-purity quartz sand and break through the bottleneck of 5N. After the chlorination is completed, the method does not require acid leaching and sand washing, has a short process flow, a simple operation process and a good impurity removal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a schematic structural diagram of an apparatus for purifying high-purity quartz sand from granite pegmatite.

[0021] Figure 2 It is a structural schematic diagram of a furnace tube of the present invention.

[0022] Figure 3 It is a schematic diagram of the internal structure of the furnace tube of the present invention.

[0023] Figure 4 It is a schematic structural diagram of the cooperation between the sampler and the collecting tank of the present invention.

[0024] Figure 5 It is a structural schematic diagram of the sampler of the present invention.

[0025] Figure 6 This is a picture of quartz particles under a microscope before chlorination. The particles appear smooth.

[0026] Figure 7 This is a picture of quartz particles after chlorination observed under a microscope. There are many microcracks on the surface of the particles.

[0027] Figure 8 This is a picture of quartz particles after chlorination observed under a microscope, with the edges of the particles cracked.

[0028] Reference numerals:

[0029] Base 1; microwave body 2; furnace tube 3; collecting tank 301; convex strip 302; air inlet pipe 4; air outlet pipe 5; drive assembly 6; rotating support 7; bearing seat 8; air inlet 9; feed port 10; air outlet 11; discharge port 12; vibrator 13; fixed support 14; chlorinated gas generator 15; microwave generator 16; micro vacuum pump 17; sampler 18. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0031] The method for purifying high-purity quartz sand from granite pegmatite of the present invention comprises the following steps:

[0032] S1. quartz sand fine material is sent in the furnace tube of purification equipment, the loading amount of quartz sand fine material and the volume ratio of furnace tube lumen are (0.5-5): 10, utilize the mode of microwave heating to heat up quartz sand, microwave power is 100-4000W, furnace tube feeds chlorinated gas under vacuum state, then i.e. 573 ℃ of insulation 10min-1h at the crystal form transition temperature of quartz, the air intake of chlorinated gas is 50-600Ml / min, keeps furnace tube rotation in the reaction process, and quartz furnace tube rotation rate is 1-10rmp / min; During the insulation period, the air pressure in the furnace chamber is repeatedly switched between positive and negative pressure, and the air pressure oscillation range is-0.4-0.1MPa, and from the perspective of safety, positive pressure should not be too high;

[0033] Quartz undergoes a reversible displacement transformation at 573°C. This transformation occurs rapidly, with the crystal's surface and interior changing instantly, accompanied by a 0.82% volume change. Holding the quartz near this temperature for a period of time allows impure metallic elements to break free from the constraints of the quartz lattice and diffuse out of the quartz crystal interface. Repeatedly switching between positive and negative pressures promotes the rupture of inclusions during this displacement transformation, exposing impurities within them.

[0034] S2. Continue to raise the temperature to the final chlorination temperature of 1000°C-1500°C and keep it warm for 60min-240min. During the insulation period, the pressure in the furnace chamber is repeatedly switched between positive and negative pressures. The furnace tube is kept rotating during the reaction, and the rotation rate of the quartz furnace tube is 1-10rmp / min. The rotating furnace tube and the convex strips on the inner wall of the furnace tube are used to promote the continuous stirring of the quartz sand and the full reaction with the gas. After the insulation is completed, the temperature is naturally lowered until the entire reaction is completed.

[0035] The temperature of high-temperature chlorination roasting is crucial. If the temperature is not high enough, the diffusion rate of the metal elements to the quartz surface / interface will be too low, limiting the reaction rate of the chlorination reaction. If the temperature is too high, the quartz sand will melt to form a solid solution, reducing the total porosity and significantly increasing the bulk density of the quartz particles. At this point, although the metal elements have been activated, the active interfaces in the solid solution quartz that allow lattice impurities to react with Cl ions are greatly reduced, which also reduces the chlorination rate of impurities. Therefore, the equilibrium temperature between the diffusion rate and reaction rate of lattice impurities in quartz under high temperature conditions is one of the most critical issues in the chlorination roasting process.

[0036] Example 1

[0037] This example uses Indian pegmatite quartz concentrate.

[0038] (1) 100 g of quartz sand concentrate was fed into the roasting furnace, and the initial microwave power was set to 1500 W and the rotation rate was set to 4 rpm.

[0039] (2) Hydrogen chloride gas was introduced into the furnace chamber under vacuum at a rate of 200 ml / min. The temperature was kept at 573°C for 10 min, and the pressure was switched between positive and negative pressures once to cause the inclusions to rupture.

[0040] (3) Continue to raise the temperature to 1100 °C and keep it at that temperature for 1 hour. During the heat preservation process, switch the air pressure state between positive and negative pressure 4 times. After the heat preservation is completed, the temperature is naturally lowered to complete the entire reaction.

[0041] The quartz sand after chlorination and roasting was tested by inductively coupled plasma optical emission spectrometry (ICP-OES). The test results are as follows:

[0042]

[0043] Table 1 ICP-OES test results of finished sand obtained in Example 1 (ppm)

[0044] By comparing the two sets of data, it can be seen that the impurities exposed by the method of the present invention have all participated in the reaction, and the interstitial charge compensation impurity atoms in the silicon-oxygen tetrahedron network after chlorination: alkali metals and divalent iron (Li + 、Na + , K+ 、Fe 2+ ) removal rate was high; alkaline earth metal elements Ca and Mg also decreased somewhat; transition metal elements Mn, Cu, Cr, and Ni, whose contents are inherently low, are not discussed here; and stubborn elements Al and Ti also decreased slightly, by 14.2% and 28.1%, respectively. The remaining 10 PPM of impurities likely resided deep within the quartz grains, unexposed and unable to participate in the chlorination reaction. They can be divided into two main components: lattice impurities bound to the tetrahedral lattice and impurities within inclusions.

[0045] Example 2

[0046] This example uses pegmatite concentrate from a place in Henan.

[0047] (1) 200 g of quartz sand concentrate was fed into the roasting furnace, and the initial microwave power was set to 2500 W and the rotation rate was set to 8 rpm.

[0048] (2) Chlorine gas was introduced into the furnace chamber under vacuum and the air flow rate was adjusted to 300 ml / min. The temperature was kept at 573°C for 20 min, and the pressure was switched between positive and negative pressure once to cause the inclusions to rupture.

[0049] (3) Continue to raise the temperature to 1200 ° C and keep it at this temperature for 1.5 hours. During the heat preservation process, switch the air pressure state between positive and negative pressure 5 times. After the heat preservation is completed, the temperature is naturally lowered to complete the entire reaction.

[0050]

[0051] The quartz sand after chlorination and roasting was tested by inductively coupled plasma optical emission spectrometry (ICP-OES). The test results are as follows:

[0052] Table 2 ICP-OES test results of finished sand obtained in Example 2 (ppm)

[0053] By comparing the two sets of data, it can be seen that the impurities exposed by the method of the present invention have all participated in the reaction, and the interstitial charge compensation impurity atoms alkali metals and divalent iron (Li+, Na+, K+, Fe 2+ ) removal rate was high, with all K removed in this experiment; alkaline earth metals Ca and Mg were slightly reduced; transition metals Mn, Cu, and Cr also saw corresponding decreases, and Ni was completely removed. The stubborn elements Al and Ti also saw slight decreases, by 35.4% and 5.2%, respectively. The small amount of impurities remaining in the quartz grains, unexposed and unable to participate in the chlorination reaction, are primarily divided into two categories: lattice impurities bound to the tetrahedral lattice and impurities within inclusions.

[0054] Figure 6 This is a picture of quartz particles under a microscope before chlorination. The particles appear smooth. Figure 7 This is a picture of quartz particles after chlorination observed under a microscope. There are many microcracks on the surface of the particles. Figure 8 This is a picture of quartz particles after chlorination observed under a microscope, with the edges of the particles cracked.

[0055] like Figure 1-Figure 5 As shown, the device for purifying high-purity quartz sand from granite pegmatite of the present invention comprises: a microwave body 2, a furnace tube 3, a chlorine gas generator 15, a micro vacuum pump 17, a drive assembly 6, a rotating support 7, a microwave generator 16 and a sampler 18, wherein the microwave body 2 is mounted on a base 1; the microwave generator 16 is disposed inside the base 1 and connected to the microwave body 2, and a temperature sensor is also installed in the microwave body 2; the furnace tube 3 is mounted in the microwave body 2, the furnace tube 3 is shuttle-shaped, and the two ends of the furnace tube 3 are respectively connected to an air inlet pipe 4 and an air outlet pipe 5; the air inlet pipe 4 It is connected to the air inlet 9, and the air outlet pipe 5 is connected to the air outlet 11; the chlorination gas generator 15 is located inside the base 1, and the chlorination gas generator 15 is connected to the air inlet pipe 4 through the air inlet 9; the micro vacuum pump 17 is located inside the base 1, and the micro vacuum pump 17 is connected to the air outlet pipe 5 through the air outlet 11; the driving component 6 is located above the base 1, and the driving component 6 is connected to the air inlet pipe 4, and the driving component 6 is used to rotate the furnace tube 3; the rotating support 7 is located above the base 1, and the rotating support 7 is rotatably connected to the air inlet pipe 4 and the air outlet pipe 5 respectively; the sampler 18 is in the shape of a spoon.

[0056] The equipment for purifying quartz sand also includes a controller (not shown), which is installed in the base 1 and is respectively connected to the microwave body 2, the drive component 6, the microwave generator 16, the chlorination gas generator 15, the micro vacuum pump 17, the vibrator 13, and the temperature sensor.

[0057] The two ends of the furnace tube 3 are connected to the air inlet pipe 4 and the air outlet pipe 5 through flanges respectively. The air inlet pipe 4 and the air outlet pipe 5 are both connected to the bearings in the bearing seat 8. The ends of the two bearing seats 8 away from the furnace tube 3 are the feed port 10 and the discharge port 12 respectively. The feed port 10 and the discharge port 12 are provided with a cover plate. The feed port 10 and the discharge port 12 are detachably connected to the cover plate by snap buckles. The feed port 10 and the discharge port 12 are both fixedly connected to the bearing seat 8.

[0058] An air inlet 9 is provided on the bearing seat 8 near the feed port 10, and an air outlet 11 is provided on the bearing seat 8 near the discharge port 12. The bearing seat 8 is connected to the air inlet pipe 4 and the air outlet pipe 5 by a rotary seal. The rotary seal connection adopts the existing technology and will not be repeated here. The width of the bearing seat 8 is greater than the width of the bearing inside the bearing seat 8. The bearing is connected to the air inlet pipe 4 and the air outlet pipe 5. The air inlet 9 or the air outlet 11 is opened on one side of the bearing at the top of the bearing seat 8.

[0059] The bottom of the bearing seat 8 is connected to the fixed support 14 through the vibrator 13, and the fixed support 14 is located above the base 1.

[0060] The gas outlet 11 is connected to a micro vacuum pump 17 , the gas inlet 9 is connected to a chlorination gas generator 15 , and valves are installed at both the gas inlet 9 and the gas outlet 11 .

[0061] The driving device 6 includes a motor, and the output port of the motor is engaged with the gear on the outer wall of the air inlet pipe 4 through a chain. When the output shaft of the motor rotates, the air inlet pipe 4 is driven to rotate through the chain and the gear. The rotation of the air inlet pipe 4 drives the furnace tube 3 and the air outlet pipe 5 to rotate.

[0062] The top of the rotating support 7 is a groove-shaped slide rail, and circular rings are fixed at positions corresponding to the rotating support 7 on the air inlet pipe 4 and the air outlet pipe 5. The circular rings cooperate with the groove-shaped slide rails. When the air inlet pipe 4 and the air outlet pipe 5 rotate, the circular rings can rotate relative to the groove-shaped slide rails, and the rotating support 7 plays the role of supporting the air inlet pipe 4 and the air outlet pipe 5.

[0063] like Figure 3 As shown, on the inwall of furnace tube 3, extend and be arranged with discontinuous and dislocated spiral ridge 302 from midpoint to two ends, drive spiral ridge 302 to rotate when furnace tube 3 rotates, thereby quartz sand sample is broken up, quartz sand powder is evenly dispersed to two ends from the centre along ridge 302 in furnace tube 3, under the continuous rotation effect of furnace tube, quartz sand moves back and forth between different spiral ridges, helps quartz sand to fully contact with chlorinated gas, makes reaction more abundant.The ridge 302 in furnace tube 3 inwall can be covered with whole furnace tube 3, also can cover half or three-quarters of furnace tube 3 inwall. In addition, since the furnace tube 3 is spindle-shaped, low in the middle and high at both ends, the quartz sand sample has a tendency to gather toward the middle of the furnace tube 3 during the rotation of the furnace tube 3. Conversely, the spiral ridges 302 can drive the quartz sand sample to have a tendency to disperse toward the two ends of the furnace tube 3. Moreover, the spiral ridges 302 extend discontinuously, leaving the quartz sand sample with randomness to return to the middle direction at the discontinuity. These two tendencies act together on the quartz sand during the reaction process, avoiding aggregation and improving the degree of stirring in the horizontal direction.

[0064] like Figure 2 and Figure 3As shown, the bottom center of the furnace tube 3 is recessed downward to form a collection trough 301, which is used to collect the purified quartz sand sample after the reaction is completed, making it easier to collect and remove. Specifically, after the reaction is completed, under the action of the vibrator 13, the purified sample moves toward the collection trough 301 while vibrating, and is finally collected in the collection trough 301. The position of the collection trough 301 is staggered with the position of the ridge 302, so that the ridge 302 does not affect the collection of quartz sand powder by the collection trough 301. That is, if the ridge 302 covers half or three-quarters of the inner wall of the furnace tube 3, the collection trough 301 is located at the bottom of the side of the inner wall of the furnace tube 3 where the ridge 302 is not present.

[0065] When the vibrator 13 is used to finally collect the purified sample, the vibrator 13 drives the air inlet pipe 4 , the air outlet pipe 5 and the furnace tube 3 to vibrate, so that the sample in the furnace tube 3 is gradually concentrated in the collection tank 301 .

[0066] The sampler 18 includes a handle and a spoon. The width and height of the spoon are both smaller than the inner diameter of the openings at both ends of the furnace tube 3. Release paper is placed inside the spoon, and the length and width of the spoon are both larger than the length and width of the collection tank 301. When the reaction is completed and sampling is required, a layer of release paper is first placed in the spoon of the sampler 18. The sampler 17 is then inserted into the furnace tube 3, with the spoon of the sampler 18 covering the collection tank 301 so that the spoon completely covers the collection tank 301. The furnace tube 3 is then rotated, and the sampler 18 rotates 180° along with the furnace tube 3, allowing the sample in the collection tank 301 to completely fall into the spoon of the sampler 18, completing the sampling.

[0067] When using the apparatus for purifying high-purity quartz sand from granite pegmatite, the apparatus first opens a feed port 10 to feed a quartz sand sample into a furnace tube 3, then seals the feed port 10; activates a drive assembly 6 to rotate the furnace tube 3, activates a microwave generator 16 to heat the microwave main body 2, evacuates the furnace tube 3 using a micro vacuum pump 17, then activates a chlorination gas generator 15 to inject chlorination gas into the furnace tube 3; when the temperature reaches 573°C, the apparatus is kept warm for 20 minutes, and the positive and negative pressures in the furnace tube 3 are adjusted by controlling the valves of the air inlet 9 and the air outlet 11, completing one positive and negative pressure switching operation; when the temperature is further increased to 1200°C, the apparatus is kept warm for 1.5 hours, and during the holding process, the positive and negative pressures in the furnace tube 3 are adjusted five times by controlling the valves of the air inlet 9 and the air outlet 11. The temperature is then naturally lowered, and the entire reaction is completed. After the reaction is completed, the discharge port 12 is opened, and a sampler 18 is used to penetrate into the furnace tube 3 to take a sample.

[0068] In the description of the present invention, it should be understood that the terms "center", "length", "width", "thickness", "up", "down", "left", "right", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0069] In addition, in the description of the present invention, “a plurality of” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0070] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0071] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0072] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0073] Although the above embodiments have been shown and described, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those skilled in the art are all within the scope of protection of the present invention.

Claims

1. A method for purifying high-purity quartz sand from granite pegmatite, characterized in that: The following steps are involved: S1. The quartz sand concentrate is fed into the furnace tube of the purification equipment, the quartz sand is heated by microwave heating, chlorinated gas is introduced into the furnace tube under vacuum, and then the crystal transition temperature of the quartz is maintained and the pressure in the furnace chamber is repeatedly switched between positive and negative pressures; the crystal transition temperature is 573 ° C, and maintaining the crystal transition temperature of the quartz means keeping it at 573 ° C for 10 min-1 h; S2 continues to heat to the final chlorination temperature and heat, during which the pressure in the furnace chamber is repeatedly switched between positive and negative pressures; after the insulation is completed, the temperature is naturally cooled to room temperature; The repeated switching of the gas pressure in the furnace cavity between positive and negative pressures means that the gas pressure in the furnace cavity is repeatedly switched between -0.4 and 0.1 MPa; During the reaction process of steps S1 and S2, the furnace tube is always kept rotating, and the rotation of the furnace tube and the disturbance of the lines on the inner wall of the furnace tube are used to promote full contact between the quartz sand concentrate and the chlorinated gas, thereby improving the reaction efficiency; The purification equipment comprises: A microwave body, wherein the microwave body is installed on a base; The furnace tube is installed in the microwave body, is shuttle-shaped, and has two ends connected to the air inlet pipe and the air outlet pipe respectively; the inner wall of the furnace tube is provided with intermittent and staggered spiral convex strips extending from the midpoint to the two ends, and the midpoint of the furnace tube is concave outward to form a collection groove; a chlorinated gas generator, the chlorinated gas generator being located inside the base and connected to the air inlet pipe; A micro vacuum pump, the micro vacuum pump is located inside the base and connected to the air outlet pipe; A drive assembly, the drive assembly being located above the base and connected to the air inlet pipe; A rotating support, the rotating support is located above the base and is rotatably connected to the air inlet pipe and the air outlet pipe respectively; A microwave generator is disposed inside the base and connected to the microwave body; The sampler is in the shape of a spoon.

2. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, wherein: The final chlorination temperature in S2 refers to 1100° C. or 1200° C., and continuing to heat to the final chlorination temperature and keeping it warm means heating to 1100° C. or 1200° C. and keeping it warm for 60 min-240 min.

3. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, wherein: The chlorination gas is chlorine gas, hydrogen chloride gas or a mixture of the two, and the ratio of the mixed gas is chlorine gas: hydrogen chloride = 1: (0.1-10).

4. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, wherein: The volume ratio of the filling amount of the quartz sand concentrate to the furnace cavity of the roasting furnace is (0.5-5):10, and the rotation speed of the furnace tube is 1-10rmp / min.

5. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, wherein: The two ends of the furnace tube are respectively connected to the air inlet pipe and the air outlet pipe through flanges. The air inlet pipe and the air outlet pipe are both connected to the bearing seat. The bottom of the bearing seat is connected to the fixed support through a vibrator. The fixed support is located above the base. The ends of the two bearing seats away from the furnace tube are the feed port and the discharge port respectively. The air inlet is set on the bearing seat close to the feed port, and the air outlet is set on the bearing seat close to the discharge port.

6. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, wherein: The sampler includes a handle and a spoon body. The width and height of the spoon body are smaller than the inner diameter of the openings at both ends of the furnace tube. Release paper is laid inside the spoon body. The length and width of the spoon body are larger than the length and width of the collection tank.

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