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

Abstract

The invention discloses a method and equipment for purifying high-purity quartz sand from granite pegmatite, which can be used for deeply removing impurities from quartz sand concentrate taking granite pegmatite as a raw material, and has a better removal effect on fluid inclusion impurities and lattice impurities which are difficult to remove in quartz. Particularly, the removal effect on interstitial ions such as alkali metal is the best, a certain removal effect on stubborn impurity elements such as aluminum and titanium is also achieved, and the purity of the high-purity quartz sand can break through the bottleneck of 5N. The method has the advantages of simplicity in operation, short flow, good impurity removal effect and the like.

Description

Technical Field

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

[0002] High-purity quartz sand plays an important role in many high-tech industries due to its unique physical and chemical properties. At present, the raw materials of high-purity quartz sand that can be industrialized and applied in large quantities mainly include vein quartz and granite pegmatite. Granite pegmatite quartz is formed by slow crystallization of high-temperature magma. The magma temperature is high and the cooling time is long. Impurities in the quartz system are easy to precipitate. Therefore, the quartz in the magmatic rock type granite pegmatite is extremely pure and has very few gas-liquid inclusions. Although the quartz content in granite pegmatite is only about 30%, the quartz grains are extremely coarse (d>5mm), and they are completely dissociated from the gangue after grinding. The impurity content of monomer quartz is very low, which is an ideal raw material for processing high-purity quartz mid-to-high-end products.

[0003] Impurities in granite pegmatite ore can be divided into three categories according to their size, distribution and formation characteristics, namely gangue mineral impurities, inclusion impurities and crystal structure impurities. In the existing high-purity quartz purification process, the removal of gangue mineral impurities has been perfected, while inclusion impurities and crystal structure impurities are the constraints to further improve 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 the crystal transition temperature of the quartz is maintained and the pressure in the furnace chamber is repeatedly switched between positive and negative pressures;

[0007] S2. Continue to heat up to the final chlorination temperature and keep warm, 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 lowered to room temperature;

[0008] During the reaction process of steps S1 and S2, the furnace tube is always kept rotating, and the rotating effect of the furnace tube and the disturbing effect of the lines on the inner wall of the furnace tube are utilized to promote the quartz sand concentrate to fully contact with the chlorinated gas, thereby improving the reaction efficiency.

[0009] The crystal transition temperature in 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 up to the final chlorination temperature and keeping it warm refers to heating up 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 -0.4-0.1 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 chamber 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 inclusion and the quartz matrix is ​​large. In the microwave field, the inclusion quickly absorbs electromagnetic waves and heats up rapidly, thereby generating a large temperature difference between it and the quartz matrix, prompting the thermal cracking of the inclusion and the generation of microcracks, creating favorable conditions for the chlorination reaction. At the same time, during the roasting and heating process, the quartz crystal will undergo a crystal phase transformation, accompanied by changes in the lattice volume, which will further promote the migration and chlorination of lattice impurities. Therefore, the microwave chlorination process can simultaneously reduce the content of inclusion impurities and lattice impurities, so that the purity of high-purity quartz sand is further improved. 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 shuttle-shaped, and two ends of the furnace tube are respectively connected to an air inlet pipe and an air outlet pipe; 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 driving component, which is located above the base and connected to the air inlet pipe; a rotating support, which is located above the base and is 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 in the shape of a spoon.

[0016] The two ends of the furnace tube are connected to the air inlet pipe and the air outlet pipe through flanges respectively. 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 arranged on the bearing seat close to the feed port, and the air outlet is arranged 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 outward 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, and the length and width of the spoon body are larger than the length and width of the collecting 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 a 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 quartz matrix, the inclusions absorb heat quickly to produce microcracks or even thermal explosions, exposing impurities; during the heating process, the quartz crystal transformation temperature is kept warm 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 is repeatedly switched between positive and negative pressures during the insulation process by using the air pressure oscillation method, so as to promote the rupture of more inclusions; a rotatable furnace tube with an uneven inner wall is used, which can 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 need 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 the equipment 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 schematic structural diagram of the sampler of the present invention.

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

[0026] Figure 7 This is a picture of quartz particles after chlorination observed under a microscope. There are many micro cracks 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; driving assembly 6; rotating support 7; bearing seat 8; air inlet 9; feed inlet 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] 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 volume ratio of the loading amount of quartz sand fine material and furnace tube lumen is (0.5-5): 10, the mode of microwave heating is utilized to heat up quartz sand, microwave power is 100-4000W, chlorinated gas is passed into furnace tube under vacuum state, then at the crystal transformation temperature of quartz i.e. 573 ℃ of insulations for 10min-1h, the air intake of chlorinated gas is 50-600Ml / min, and furnace tube is kept rotating all the time in the reaction process, and the 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 pressures, 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 surface and inside of the crystal changing instantly, accompanied by a 0.82% volume change. Keeping the temperature near the crystal transformation temperature for a certain period of time is conducive to the impurity metal elements in the quartz to break free from the constraints of the quartz lattice and diffuse and migrate out of the quartz crystal interface. Repeated switching between positive and negative pressure is conducive to promoting the rupture of inclusions when the crystal undergoes a displacement transformation, exposing the impurities inside the inclusions.

[0034] S2. Continue to raise the temperature to the final chlorination temperature, i.e., 1000°C-1500°C, and keep it warm for 60min-240min. During the warm-keeping period, the gas pressure in the furnace chamber is repeatedly switched between positive and negative pressures. The furnace tube is always 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 to fully react with the gas. After the warm-keeping 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 metal elements to the quartz surface / interface is too low, which will limit the reaction rate of the chlorination reaction. If the temperature is too high, the quartz sand will melt to form a solid solution, which will reduce the total porosity and greatly increase the volume density of the quartz particles. At this time, although the metal elements have been activated, the active interface in the solid solution quartz that allows lattice impurities to react with Cl ions is greatly reduced, which will also reduce 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 a roasting furnace, and the initial microwave power was set to 1500 W and the rotation rate to 4 rpm.

[0039] (2) Hydrogen chloride gas is supplied into the furnace chamber under vacuum at a rate of 200 ml / min. The temperature is kept at 573°C for 10 min, and the pressure is 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 roasting was tested by inductively coupled plasma optical emission spectrometer (ICP-OES), and 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. The interstitial charge compensation impurity atoms in the silicon-oxygen tetrahedral network after chlorination: alkali metals and divalent iron (Li + 、Na + , K+ , Fe 2+ ) removal rate is high; alkaline earth metal elements Ca and Mg are also reduced; transition metal elements Mn, Cu, Cr, Ni have low contents and are not discussed; stubborn elements Al and Ti also slightly decreased, by 14.2% and 28.1% respectively. The remaining 10PPM impurities that have not been completely removed should be located deep inside the quartz particles. Because they are not exposed and cannot participate in the chlorination reaction, they are mainly divided into two parts, namely, lattice impurities bound to the tetrahedral lattice and impurities inside the 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 a roasting furnace, and the initial microwave power was set to 2500 W and the rotation rate to 8 rpm.

[0048] (2) Chlorine gas is delivered into the furnace chamber under vacuum and the air intake is adjusted to 300 ml / min. The temperature is kept at 573°C for 20 minutes and the pressure is switched between positive and negative pressures 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 for 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 roasting was tested by inductively coupled plasma optical emission spectrometer (ICP-OES), and 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+) in the silicon-oxygen tetrahedral network after chlorination 2+ ) removal rate is high, all K elements in this experiment were removed; alkaline earth metal elements Ca and Mg were slightly reduced; transition metal elements Mn, Cu, Cr were also reduced accordingly, and Ni element was completely removed. Stubborn elements Al and Ti also decreased slightly, by 35.4% and 5.2% respectively. The remaining small amount of impurities that were not completely removed should be located deep inside the quartz particles. Because they are not exposed and cannot participate in the chlorination reaction, they are mainly divided into two parts, namely lattice impurities bound to the tetrahedral lattice and impurities inside the inclusions.

[0054] Figure 6 This is a picture of quartz particles before chlorination observed under a microscope. The particles appear flat. Figure 7 This is a picture of quartz particles after chlorination observed under a microscope. There are many micro cracks 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 chlorinated gas generator 15, a micro vacuum pump 17, a driving 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 arranged inside the base 1, and the microwave generator 16 is 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 driving 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 respectively connected to the air inlet pipe 4 and the air outlet pipe 5 through flanges. 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 cover plates. The feed port 10 and the discharge port 12 are detachably connected to the cover plates through buckles, and the feed port 10 and the discharge port 12 are both fixedly connected to the bearing seat 8.

[0058] An air inlet 9 is arranged on the bearing seat 8 near the feed port 10, and an air outlet 11 is arranged 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. An air inlet 9 or an 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 a fixed support 14 via a 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 meshed with the gear on the outer wall of the air inlet pipe 4 through a chain, so that when the output shaft of the motor rotates, the air inlet pipe 4 will be driven to rotate through the chain and the gear, and the rotation of the air inlet pipe 4 will drive 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, the inner wall of the furnace tube 3 is extended from the midpoint to both ends with discontinuous and misplaced spiral convex strips 302, and the spiral convex strips 302 are driven to rotate while the furnace tube 3 rotates, thereby breaking up the quartz sand sample, making the quartz sand powder evenly dispersed from the middle to both ends in the furnace tube 3 along the convex strips 302, and under the continuous rotation of the furnace tube, the quartz sand moves back and forth between different spiral convex strips, which helps the quartz sand to fully contact with the chlorinated gas, so that the reaction is more sufficient. The convex strips 302 in the inner wall of the furnace tube 3 can be spread all over the whole furnace tube 3, and can also cover half or three quarters of the inner wall of the furnace tube 3. In addition, since the furnace tube 3 is shuttle-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 convex strips 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 convex strips 302 extend discontinuously, leaving randomness for the quartz sand sample to return to the middle direction at the discontinuity. The two tendencies act together on the quartz sand during the reaction process to avoid aggregation and improve the degree of stirring in the horizontal direction.

[0064] like Figure 2 and Figure 3As shown, the middle of the bottom of the furnace tube 3 is sunken downward to form a collecting groove 301, which is used to collect the purified quartz sand samples together after the reaction is completed, so as to facilitate collection and removal. Specifically, after the reaction is completed, under the action of the vibrator 13, the purified samples move toward the collecting groove 301 while vibrating, and finally collect in the collecting groove 301. The position of the collecting groove 301 is staggered with the position of the convex strip 302, so that the convex strip 302 cannot affect the collection of quartz sand powder by the collecting groove 301, that is, if the convex strip 302 covers half or three quarters of the inner wall of the furnace tube 3, the collecting groove 301 is located at the bottom of one side of the inner wall of the furnace tube 3 without the convex strip 302.

[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 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 3, a release paper is placed inside the spoon body, and the length and width of the spoon body are larger than the length and width of the collecting tank 301. When the reaction is completed and sampling is required, a layer of release paper is first laid in the spoon body of the sampler 18, and then the sampler 17 is sent into the furnace tube 3, and the spoon body of the sampler 18 is covered above the collecting tank 301, so that the spoon body can completely cover the collecting tank 301, and then the furnace tube 3 is rotated, and the sampler 18 is rotated 180° with the furnace tube 3 at this time, so that the sample in the collecting tank 301 can completely fall into the spoon body of the sampler 18, and the sampling is completed.

[0067] When the device for purifying high-purity quartz sand from granite pegmatite of the present invention is used, first open the feed port 10 to feed the quartz sand sample into the furnace tube 3, and then seal the feed port 10; start the drive assembly 6 to rotate the furnace tube 3, start the microwave generator 16, start the microwave main body 2 to start heating, vacuumize through the micro vacuum pump 17, and then open the chlorination gas generator 15 to flush chlorination gas into the furnace tube 3; when the temperature rises to 573°C, keep it warm for 20 minutes, and adjust the positive and negative pressures in the furnace tube 3 by controlling the valves of the air inlet 9 and the air outlet 11, and complete the positive and negative pressure switching once; continue to heat up to 1200°C and keep it warm for 1.5 hours. During the heat preservation process, adjust the positive and negative pressure switching in the furnace tube 3 5 times by controlling the valves of the air inlet 9 and the air outlet 11. After the heat preservation is completed, the temperature is naturally lowered, and the entire reaction is completed. After the reaction is completed, open the discharge port 12, and use the sampler 18 to go deep into the furnace tube 3 to take samples.

[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, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0070] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0072] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0073] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill 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; S2. Continue to heat up to the final chlorination temperature and keep warm, 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 lowered to room temperature; During the reaction process of steps S1 and S2, the furnace tube is always kept rotating, and the rotating effect of the furnace tube and the disturbing effect of the lines on the inner wall of the furnace tube are utilized to promote the quartz sand concentrate to fully contact with the chlorinated gas, thereby improving the reaction efficiency.

2. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, characterized in that: The crystal transition temperature in S1 is 573° C., and maintaining the crystal transition temperature of quartz means keeping the temperature at 573° C. for 10 min-1 h.

3. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, characterized in that: The final chlorination temperature in S2 refers to 1000°C-1500°C, and continuing to heat up to the final chlorination temperature and keeping it warm refers to heating up to 1000°C-1500°C and keeping it warm for 60min-240min.

4. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, characterized in that: 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 -0.4-0.1 MPa.

5. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, characterized in that: 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).

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

7. The method for purifying high-purity quartz sand from granite pegmatite according to claim 1, characterized in that: The purification equipment comprises: A microwave body, wherein the microwave body is mounted on a base; A furnace tube, which is installed in the microwave body, is shuttle-shaped, and has two ends connected to an air inlet pipe and an air outlet pipe respectively; A chlorinated gas generator, wherein the chlorinated gas generator is located inside the base and connected to the air inlet pipe; A micro vacuum pump, wherein the micro vacuum pump is located inside the base and connected to the air outlet pipe; A driving assembly, wherein the driving assembly is located above the base and connected to the air inlet pipe; A rotating support, the rotating support is located above the base, and the rotating support is rotatably connected to the air inlet pipe and the air outlet pipe respectively; A microwave generator, wherein the microwave generator is disposed inside the base and connected to the microwave body; The sampler is in the shape of a spoon.

8. The method for purifying high-purity quartz sand from granite pegmatite according to claim 7, characterized in that: The two ends of the furnace tube are connected to the air inlet pipe and the air outlet pipe through flanges respectively. 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 arranged on the bearing seat close to the feed port, and the air outlet is arranged on the bearing seat close to the discharge port.

9. The method for purifying high-purity quartz sand from granite pegmatite according to claim 7, characterized in that: 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 outward to form a collecting groove.

10. The method for purifying high-purity quartz sand from granite pegmatite according to claim 9, characterized in that: 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, and the length and width of the spoon body are larger than the length and width of the collecting tank.

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