Impurity and hydroxyl removal method and equipment for quartz sand

Abstract

The method comprises the following steps: feeding a quartz sand raw material into a vertical glass tube in a vertical high-temperature furnace through a feeding device, heating the room temperature in the vertical glass tube to 1000-1100 DEG C, carrying out heat preservation on the quartz sand in the vertical glass tube, and cooling to prepare the quartz sand with low hydroxyl and low metal impurities. Wherein the heating and heat preservation processes are both in the atmosphere, and the raw material heating stage is in the gas atmosphere, so that the quartz sand is prevented from being bonded into blocks in the heating process; nitrogen and helium are used for removing hydroxyl in the quartz sand, and hydrogen chloride and chlorine are used for removing metal impurities and hydroxyl; in the front heat preservation section, nitrogen or helium drives hydrogen chloride / chlorine to make full contact with quartz sand, the metal impurity removal efficiency is higher, and meanwhile the chloride consumption is reduced; according to the equipment, gas is in full contact with quartz sand in a lower ventilation mode, the impurity removal and hydroxyl removal efficiency is higher, and meanwhile, the quartz sand is prevented from being bonded into blocks in a high-temperature environment.

Description

Technical Field

[0001] The invention relates to the technical field of quartz sand impurity removal, and in particular to a quartz sand impurity removal and dehydroxylation method and equipment thereof. Background Art

[0002] Most of the existing high-purity quartz sand raw materials for semiconductors are imported. The purity of natural sand depends on the quality of the ore. Due to the limited high-quality ore sources, the quality of quartz sand is unstable and it is difficult to meet the requirements of the semiconductor industry. In addition to the influence of the raw ore, the main reason is that the key impurity removal process in the production process is not advanced.

[0003] Since synthetic sand is prepared by chemical methods, quartz sand with a total impurity content of less than 10ppm can be prepared by optimizing raw materials, but it is difficult to stably produce high-purity synthetic quartz sand in large quantities. Currently, synthetic sand production is in the pilot stage. In addition to optimizing raw materials to reduce impurity content, the impurity content of synthetic sand can also be reduced through other production links.

[0004] In addition to high requirements for metal impurities, quartz glass products for semiconductors also have certain requirements for hydroxyl content. The sources of hydroxyl in quartz glass products mainly include two parts: one part is the hydroxyl contained in the quartz sand itself, and the other part is the hydroxyl generated during the high-temperature melting process. The former accounts for a higher proportion. High hydroxyl content seriously limits the quality of high-quality quartz glass and its products.

[0005] Therefore, a quartz sand impurity removal and dehydroxylation method and equipment are proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a quartz sand impurity removal and dehydroxylation method and equipment to solve the technical problems of low quality and high hydroxyl content of quartz sand for semiconductors. Quartz sand for semiconductors with a total amount of metal impurities as low as 1ppm and a hydroxyl content as low as 1ppm can be prepared by the method and equipment of the present invention.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A quartz sand impurity removal and dehydroxylation method comprises the following steps:

[0009] S1. Feeding synthetic or natural quartz sand into a vertical glass tube in a vertical high-temperature furnace through a feeding device, so that the room temperature in the vertical glass tube is heated to 1000-1100° C.;

[0010] S2, heat-insulating the synthetic or natural quartz sand in the vertical glass tube in step S1, and then cooling it down, wherein the heating and heat-insulating processes are both carried out under atmosphere;

[0011] S3, discharging the synthetic or natural quartz sand in step S2 from a discharging device to obtain quartz sand with low hydroxyl group and low metal impurities.

[0012] As a further solution of the present invention, the insulation time in step S2 is 2 to 4 hours.

[0013] As a further embodiment of the present invention, the atmosphere in step S2 is one or two of nitrogen, helium, hydrogen chloride and chlorine.

[0014] As a further solution of the present invention, one of nitrogen or helium is introduced during the temperature rising stage in step S2.

[0015] As a further scheme of the present invention, the ventilation process in the insulation stage in step S2 is divided into a front insulation section and a rear insulation section based on a ventilation time ratio of 1:0.8 to 1.5, and one of hydrogen chloride and nitrogen, or chlorine and nitrogen, or hydrogen chloride and helium is introduced into the front insulation section, and one of nitrogen or helium is introduced into the rear insulation section.

[0016] As a further embodiment of the present invention, the flow rate of nitrogen and helium in the front insulation section is 0.16-1m 3 / h, the flow rate of hydrogen chloride and chlorine is 5~30L / h, and the flow rate of nitrogen and helium in the rear insulation section is 0.16~1m 3 / h.

[0017] The present invention provides a quartz sand impurity removal and dehydroxylation equipment, comprising the vertical high-temperature furnace, the vertical glass tube, the discharging device and the feeding device as described above;

[0018] Vertical high temperature furnaces are used to heat synthetic or natural quartz sand to the required temperature;

[0019] The vertical glass tube is used to contain synthetic or natural quartz sand, and a plurality of the vertical glass tubes are evenly distributed inside the vertical high-temperature furnace;

[0020] The discharging device is used to discharge low-hydroxyl and low-metal impurity quartz sand, and the bottoms of several vertical glass tubes are equipped with a discharging device;

[0021] The feeding device is used for feeding synthetic or natural quartz sand, and the tops of several vertical glass tubes are equipped with the feeding device.

[0022] As a further solution of the present invention, the vertical glass tube includes a glass tube placed inside a vertical high-temperature furnace, and a quartz glass plug is provided at the bottom end of the glass tube;

[0023] The glass tube vertically penetrates the interior of the vertical high-temperature furnace, a conical tube is provided at the bottom of the glass tube, a connecting tube is provided at the bottom of the conical tube, a second convex ring is integrally formed at the bottom of the connecting tube, and the top of the quartz glass plug is detachably connected to the second convex ring through a buckle;

[0024] A rubber ring gasket is embedded at the bottom of the second convex ring, and the bottom of the rubber ring gasket contacts the top of the quartz glass plug;

[0025] The discharging device includes a feeding tube that can be assembled on the bottom end of the connecting tube. The top of the feeding tube is provided with a third convex ring that matches the second convex ring. The top of the third convex ring contacts the bottom of the rubber ring pad. The outer peripheral surface of the feeding tube is provided with two symmetrical hanging ears.

[0026] As a further solution of the present invention, the feeding device includes a material guiding assembly, a funnel is provided on the top of the material guiding assembly, and a support rod is provided on the bottom of the material guiding assembly;

[0027] The material guiding assembly includes a bent tube that can be sleeved on the top of the vertical glass tube. The upper end of the bent tube away from the vertical glass tube is integrally formed with an inclined tube that is inclined upward. The bottom end of the funnel is connected to the top of the inclined tube. The support rod is located at the bottom of the inclined tube, and the bottom end of the support rod can contact the top of the vertical high-temperature furnace.

[0028] As a further solution of the present invention, a quartz sand impurity removal and dehydroxylation equipment of the present invention further includes a vent pipe, an air suction mechanism and a glass cover;

[0029] The ventilation pipe is connected to the connecting pipe for ventilation of nitrogen, helium, hydrogen chloride and chlorine;

[0030] A glass cover is provided at the upper end of a plurality of glass tubes; the glass cover comprises a glass cover body which is sleeved on the top end of the glass tube, the glass cover body is in a semi-hollow spherical shape, and an air outlet pipe is connected at the center of the top of the glass cover body;

[0031] The suction mechanism is used to cooperate with an external suction fan to perform suction operations, and the suction mechanism is located above the vertical high-temperature furnace;

[0032] The air suction mechanism comprises an air suction pipe connected with an external suction fan, the bottom of the air suction pipe is connected with a plurality of arc-shaped pipes, and the arc-shaped pipes are arranged in a one-to-one correspondence with the plurality of air outlet pipes.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. A quartz sand impurity removal and dehydroxylation method of the present invention allows the quartz sand to be in a gas atmosphere during the entire heating stage, thereby preventing the quartz sand from sticking together during the heating process and ensuring that the contact environment of the quartz sand is sufficiently clean; nitrogen and helium are used to remove hydroxyl groups in the quartz sand, and hydrogen chloride and chlorine are used to remove metal impurities and hydroxyl groups; in the front insulation stage, the two gases are simultaneously introduced into a glass tube, so that nitrogen or helium drives hydrogen chloride / chlorine to fully contact the material, thereby achieving high efficiency in removing metal impurities, while reducing the amount of chloride used, reducing environmental pollution, and reducing production costs.

[0035] 2. The quartz sand impurity removal and dehydroxylation equipment of the present invention adopts a downward ventilation method through a ventilation pipe, so that the atmosphere gas fully contacts the quartz sand, the impurity removal and dehydroxylation efficiency is higher, and at the same time, the quartz sand is prevented from sticking together and blocking the connecting pipe under a high temperature environment; the exhaust gas is completely sucked into the spray tower by an oblique suction method through the suction mechanism, so as to prevent impurities from falling into the glass tube at a low temperature and polluting the material.

[0036] 3. The quartz sand impurity removal and dehydroxylation equipment of the present invention connects the glass tube and the discharging device through a quartz glass plug, thereby solving the technical problem that the glass tube is too brittle to be hard-connected; in order to ensure a smooth connection between the discharging device and the glass tube, symmetrical hanging ears are designed on the outer peripheral surface of the discharge tube to facilitate connection; a glass cover is provided at the upper end of the glass tube to reduce the air outlet and prevent impurities from falling and contaminating the material; in the continuous production process, a feeding device is provided to facilitate feeding, and a funnel is used for feeding, and a support rod is provided for positioning to prevent shaking during the feeding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only examples of the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a flow chart of a method for removing impurities and dehydroxylation from quartz sand according to an embodiment of the present invention;

[0039] Figure 2 It is a schematic diagram of the structure of the equipment of the embodiment of the present invention;

[0040] Figure 3 It is a schematic cross-sectional structure diagram of the equipment according to the embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of a partial explosion structure of the equipment of an embodiment of the present invention;

[0042] Figure 5 for Figure 4 The enlarged structural diagram at A in the middle;

[0043] Figure 6 It is a structural schematic diagram of a feeding device in an embodiment of the present invention;

[0044] Figure 7 It is a schematic diagram of the cross-sectional structure of the feeding device in the equipment of an embodiment of the present invention.

[0045] Reference numerals: 100, vertical high temperature furnace;

[0046] 200, vertical glass tube; 210, glass tube; 211, first convex ring; 212, tapered tube; 213, connecting tube; 2131, second convex ring; 220, quartz glass plug; 230, rubber ring gasket;

[0047] 300, ventilator;

[0048] 400, suction mechanism; 410, suction pipe; 420, arc pipe;

[0049] 500, discharging device; 510, feeding pipe; 511, third convex ring; 520, hanging ear;

[0050] 600, glass cover; 610, glass cover body; 620, air outlet pipe;

[0051] 700, feeding device; 710, material guiding assembly; 711, elbow; 712, inclined pipe; 720, funnel; 730, support rod. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the embodiments of the present invention.

[0054] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can be the internal connection of two components; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0055] See also Figure 2-7 As shown, a quartz sand impurity removal and dehydroxylation equipment according to an embodiment of the present invention includes a vertical high-temperature furnace 100, a vertical glass tube 200, and a discharging device 500.

[0056] The vertical high temperature furnace 100 is used to heat synthetic or natural quartz sand.

[0057] The vertical glass tube 200 is used to contain synthetic or natural quartz sand, and a plurality of vertical glass tubes 200 are evenly distributed inside the vertical high-temperature furnace 100 .

[0058] The discharging device 500 is used to discharge the quartz sand after impurity removal and dehydroxylation, and the bottom of several vertical glass tubes 200 is equipped with the discharging device 500.

[0059] See also Figure 3-4 As shown, the vertical glass tube 200 includes a glass tube 210 located inside the vertical high-temperature furnace 100, and a quartz glass plug 220 is provided at the bottom end of the glass tube 210. The glass tube 210 vertically penetrates the inside of the vertical high-temperature furnace 100, and a tapered tube 212 is provided at the bottom end of the glass tube 210, and a connecting tube 213 is provided at the bottom end of the tapered tube 212, and a second convex ring 2131 is integrally formed at the bottom end of the connecting tube 213, and the top end of the quartz glass plug 220 is detachably connected to the second convex ring 2131 through a buckle, and a rubber ring gasket 230 is embedded at the bottom of the second convex ring 2131, and the bottom of the rubber ring gasket 230 is in contact with the top end of the quartz glass plug 220.

[0060] See also Figure 5 As shown, the discharge device 500 includes a discharge tube 510 assembled at the bottom end of the connecting tube 213, and a third convex ring 511 matched with the second convex ring 2131 is provided at the top of the discharge tube 510, and the top of the third convex ring 511 contacts the bottom of the rubber ring gasket 230, and two symmetrical hanging ears 520 are provided on the outer peripheral surface of the discharge tube 510 to ensure a smooth connection between the discharge device and the glass tube to avoid the inability to perform hard connection due to the high brittleness of the glass.

[0061] During the continuous production process, a feeding device 700 is provided in the embodiment of the present invention for the convenience of feeding. The feeding device 700 is used to feed synthetic or natural quartz sand, and the tops of several vertical glass tubes 200 are equipped with the feeding device 700.

[0062] See also Figure 6-7 As shown, the feeding device 700 includes a material guide assembly 710, a funnel 720 is provided at the top of the material guide assembly 710, and a support rod 730 is provided at the bottom of the material guide assembly 710. The material guide assembly 710 includes a curved tube 711, and an inclined tube 712 arranged upwardly tilted is integrally formed at the upper end of the curved tube 711, the bottom end of the funnel 720 is connected to the top of the inclined tube 712, and the support rod 730 is located at the bottom of the inclined tube 712; wherein the funnel 720 serves as a feeding port, and the support rod 730 is used to prevent the feeding device 700 from shaking. When the above-mentioned feeding device 700 is located on the vertical high-temperature furnace 100, a feeding device 700 that moves to a plurality of vertical glass tubes 200 for feeding can be provided, and a plurality of vertical glass tubes 200 can also be equipped with a plurality of feeding devices 700 corresponding to each other.

[0063] In order to make the chloride and quartz sand fully contact and react, and to use the fluidity of the gas to prevent the quartz sand from sticking together at high temperature, a quartz sand impurity removal and dehydroxylation equipment according to an embodiment of the present invention further includes a vent pipe 300, an air suction mechanism 400 and a glass cover 600.

[0064] See also Figure 5 As shown, the ventilation pipe 300 is connected to the connecting pipe 213; and the ventilation pipe 300 is connected to the atmospheric gas.

[0065] See also Figure 3-4 As shown, in order to reduce the air outlet and prevent impurities from falling and contaminating the quartz sand, a glass cover 600 is provided on the upper end of several glass tubes 210; the glass cover 600 includes a glass cover body 610 sleeved on the top of the glass tube 210, the glass cover body 610 is semi-hollow spherical, and an air outlet pipe 620 is connected to the center of the top of the glass cover body 610.

[0066] The suction mechanism 400 cooperates with an external suction fan to perform suction operation, and the suction mechanism 400 is located above the vertical high-temperature furnace 100. Figure 2 As shown, the air suction mechanism 400 includes an air suction pipe 410 connected to an external suction fan, and the bottom of the air suction pipe 410 is connected to a plurality of arc tubes 420 , and the plurality of arc tubes 420 correspond one-to-one to a plurality of air outlet pipes 620 .

[0067] Embodiment 1:

[0068] like Figure 1 As shown, a method for removing impurities and dehydroxylation from quartz sand according to an embodiment of the present invention uses synthetic quartz sand as a raw material, and comprises the following steps:

[0069] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and synthetic quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0070] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 200. A gas flow rate of 0.6 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of nitrogen, start the vertical high temperature furnace and raise the temperature to 1100℃ from 100℃, keep it at this temperature for 5h, of which the mixed gas of hydrogen chloride and nitrogen is passed in the first 2h, and the nitrogen flow rate is 0.6m 3 / h, the hydrogen chloride flow rate is 10L / h, and the gas flow rate in the last 3h is 0.6m 3 / h of nitrogen; during the heating and insulation process, start the external suction fan to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0071] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0072] The hydroxyl content in the synthetic quartz sand raw material of the above embodiment 1 is 150ppm, and the content of 13 typical metal impurities is 4ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 1 is 0.5ppm, and the obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The quartz ingot is sliced ​​and tested, and the hydroxyl content in the quartz ingot is 0.2ppm.

[0073] Embodiment 2:

[0074] Using natural quartz sand as raw material, the impurity removal and dehydroxylation method comprises the following steps:

[0075] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and natural quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0076] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 210. A gas flow rate of 0.5 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of nitrogen, start the vertical high temperature furnace and raise the temperature to 1100℃ from 100℃, and keep it at this temperature for 3h, of which the mixed gas of hydrogen chloride and nitrogen is passed in the first 1.5h, and the nitrogen flow rate is 0.5m 3 / h, the hydrogen chloride flow rate is 20L / h, and the gas flow rate in the last 1.5h is 0.5m 3 / h of nitrogen, during the heating and insulation process, the external suction fan is started to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0077] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0078] The hydroxyl content in the natural quartz sand raw material of the above embodiment 2 is 50ppm, and the content of 13 typical metal impurities is 100ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 2 is 10.8ppm, and the obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The quartz ingot is sliced ​​and tested, and the hydroxyl content in the quartz ingot is 3.9pm.

[0079] Embodiment 3:

[0080] Using natural quartz sand as raw material, the impurity removal and dehydroxylation method comprises the following steps:

[0081] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and natural quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0082] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 210. A gas flow rate of 0.2 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of helium, start the vertical high temperature furnace and raise the temperature to 1000℃, keep it at this temperature for 3h, of which the mixed gas of hydrogen chloride and helium is passed in the first 1.5h, and the helium flow rate is 0.2m 3 / h, the hydrogen chloride flow rate is 15L / h, and the gas flow rate in the last 1.5h is 0.2m 3 / h of helium, during the heating and insulation process, the external suction fan is started to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0083] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0084] The hydroxyl content in the natural quartz sand raw material of the above embodiment 3 is 50ppm, and the content of 13 typical metal impurities is 100ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 3 is 15.6ppm, and the obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The quartz ingot is sliced ​​and tested, and the hydroxyl content in the quartz ingot is 8.4ppm.

[0085] Embodiment 4:

[0086] Using natural quartz sand as raw material, the impurity removal and dehydroxylation method comprises the following steps:

[0087] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and natural quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0088] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 210. A gas flow rate of 0.5 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of nitrogen, start the vertical high temperature furnace and raise the temperature to 1100℃ from 100℃, and keep it at this temperature for 3h, of which the mixed gas of chlorine and nitrogen is passed in the first 1.5h, and the nitrogen flow rate is 0.5m 3 / h, the chlorine flow rate is 20L / h, and the gas flow rate in the last 1.5h is 0.5m 3 / h of nitrogen, during the heating and insulation process, the external suction fan is started to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0089] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0090] The hydroxyl content in the natural quartz sand raw material of the above embodiment 4 is 50ppm, and the content of 13 typical metal impurities is 100ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 4 is 8.3ppm, and the obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The quartz ingot is sliced ​​and tested, and the hydroxyl content in the quartz ingot is 2.4ppm.

[0091] Embodiment 5:

[0092] Using synthetic quartz sand as raw material, the impurity removal and dehydroxylation method comprises the following steps:

[0093] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and synthetic quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0094] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 200. A gas flow rate of 0.6 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of nitrogen, start the vertical high temperature furnace and raise the temperature to 1100℃ from 100℃, keep it at this temperature for 5h, of which the mixed gas of hydrogen chloride and nitrogen is passed in the first 2h, and the nitrogen flow rate is 0.6m 3 / h, the hydrogen chloride flow rate is 5L / h, and the gas flow rate in the last 2h is 0.6m 3 / h of nitrogen; during the heating and insulation process, start the external suction fan to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0095] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0096] The hydroxyl content in the raw material of the above embodiment 5 is 150ppm, and the content of 13 typical metal impurities is 4ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 5 is 1.2ppm. The obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The slice test shows that the hydroxyl content in the quartz ingot is 0.8ppm.

[0097] Embodiment 6:

[0098] Using natural quartz sand as raw material, the impurity removal and dehydroxylation method comprises the following steps:

[0099] First, the feeding device 700 is assembled on the top of the vertical glass tube 200 so that the bottom end of the support rod 730 contacts the top of the vertical high-temperature furnace 100 , and natural quartz sand is added into the vertical glass tube 200 through the cooperation of the funnel 720 and the material guide assembly 710 .

[0100] Next, the feed device 700 is removed, and the glass cover 600 is assembled on the top of the vertical glass tube 210. A gas flow rate of 0.5 m / s is introduced into the glass tube 210 through the butt joint 310 and the connecting tube 213. 3 / h of nitrogen, start the vertical high temperature furnace and raise the temperature to 1100℃ from 100℃, keep it at this temperature for 5h, of which the mixed gas of hydrogen chloride and nitrogen is passed in the first 2.5h, and the nitrogen flow rate is 0.5m 3 / h, the hydrogen chloride flow rate is 20L / h, and the gas flow rate in the last 2.5h is 0.5m 3 / h of nitrogen, during the heating and insulation process, the external suction fan is started to suck the exhaust gas into the spray tower through the arc pipe 420 and the suction pipe 410.

[0101] After cooling, the quartz glass plug 220 is removed, and the discharge device 500 is assembled at the bottom end of the connecting pipe 213 to collect the quartz sand.

[0102] The hydroxyl content in the natural quartz sand raw material of the above embodiment 6 is 50ppm, and the content of 13 typical metal impurities is 100ppm; the content of 13 typical metal impurities in the quartz sand obtained after impurities removal in the above embodiment 6 is 8.6ppm, and the obtained quartz sand is melted into a quartz ingot by a high-frequency plasma flame method according to conventional processes. The quartz ingot is sliced ​​and tested, and the hydroxyl content in the quartz ingot is 2.7ppm.

[0103] In summary, the quartz sand impurity removal and dehydroxylation method and equipment of the present invention are suitable for the removal of metal impurities and hydroxyl groups of natural quartz sand and synthetic quartz sand, and have obvious purification effects on the two types of sand. The total amount of metal impurities in synthetic quartz sand can be reduced to 0.5ppm, and the hydroxyl group can be reduced to within 0.2ppm. The total amount of metal impurities in natural quartz sand can be reduced to 8ppm, and the hydroxyl group can be reduced to within 2ppm. Compared with Example 1 and Example 5, the larger the chloride flow rate, and the longer the chloride ventilation time in Comparative Example 2 and Example 6, the better the impurity removal effect.

[0104] The above shows and describes the basic principles of the present invention. The above are only preferred embodiments of the present invention and are not intended to limit the present invention. The above embodiments and descriptions in the specification are only intended to illustrate the principles of the present invention. Without departing from the scope of the present invention, any modifications, equivalent substitutions and improvements made within the spirit and scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for removing impurities and dehydroxylation from quartz sand, characterized in that: The steps include: S1, feeding synthetic or natural quartz sand into a vertical glass tube (200) in a vertical high-temperature furnace (100) through a feeding device (700), so that the room temperature in the vertical glass tube (200) is raised to 1000-1100° C.; S2, heat-insulating the synthetic or natural quartz sand in the vertical glass tube (200) in step S1, and then cooling it down, wherein the heating and heat-insulating processes are both carried out under atmosphere; S3. The synthetic or natural quartz sand in step S2 is discharged from the discharging device (500) to obtain quartz sand with low hydroxyl group and low metal impurities.

2. The quartz sand impurity removal and dehydroxylation method according to claim 1, characterized in that: The insulation time in step S2 is 2 to 4 hours.

3. The quartz sand impurity removal and dehydroxylation method according to claim 2, characterized in that: The atmosphere of step S2 is one or two of nitrogen, helium, hydrogen chloride and chlorine.

4. The quartz sand impurity removal and dehydroxylation method according to claim 3, characterized in that: In the step S2, one of nitrogen and helium is introduced during the heating stage.

5. The quartz sand impurity removal and dehydroxylation method according to claim 4, characterized in that: The ventilation process in the insulation stage in step S2 is divided into a front insulation section and a rear insulation section based on a ventilation time ratio of 1:0.8-1.5, wherein one of hydrogen chloride and nitrogen, or chlorine and nitrogen, or hydrogen chloride and helium is introduced into the front insulation section, and one of nitrogen or helium is introduced into the rear insulation section.

6. The quartz sand impurity removal and dehydroxylation method according to claim 5, characterized in that: The flow rate of nitrogen and helium in the front insulation section is 0.16~1m 3 / h, the flow rate of hydrogen chloride and chlorine is 5-30L / h; the flow rate of nitrogen and helium in the rear insulation section is 0.16-1m 3 / h.

7. A quartz sand impurity removal and dehydroxylation equipment, characterized in that: It comprises the vertical high-temperature furnace (100), the vertical glass tube (200), the discharging device (500) and the feeding device (700) according to any one of claims 1 to 6; The vertical high temperature furnace (100) heats synthetic or natural quartz sand to a desired temperature; The vertical glass tube (200) contains synthetic or natural quartz sand, and a plurality of the vertical glass tubes (200) are evenly distributed inside the vertical high-temperature furnace (100); The discharging device (500) is used to discharge materials, and the bottoms of the plurality of vertical glass tubes (200) are each equipped with a discharging device (500); The feeding device (700) is used to feed synthetic or natural quartz sand, and the tops of a plurality of vertical glass tubes (200) are equipped with the feeding device (700).

8. The quartz sand impurity removal and dehydroxylation equipment according to claim 7, characterized in that: The vertical glass tube (200) comprises a glass tube (210) located inside the vertical high-temperature furnace (100), and a quartz glass plug (220) is provided at the bottom end of the glass tube (210); The glass tube (210) vertically penetrates the interior of the vertical high-temperature furnace (100); a conical tube (212) is provided at the bottom end of the glass tube (210); a connecting tube (213) is provided at the bottom end of the conical tube (212); a second convex ring (2131) is integrally formed at the bottom end of the connecting tube (213); and the top end of the quartz glass plug (220) is detachably connected to the second convex ring (2131) via a buckle; A rubber ring gasket (230) is embedded in the bottom of the second convex ring (2131), and the bottom of the rubber ring gasket (230) is in contact with the top of the quartz glass plug (220); The discharging device (500) comprises a discharge pipe (510) mounted on the bottom end of the connecting pipe (213); a third convex ring (511) matching the second convex ring (2131) is provided at the top end of the discharge pipe (510); the top of the third convex ring (511) contacts the bottom of the rubber ring gasket (230); and two symmetrical hanging ears (520) are provided on the outer peripheral surface of the discharge pipe (510).

9. The quartz sand impurity removal and dehydroxylation equipment according to claim 8, characterized in that: The feeding device (700) comprises a material guiding assembly (710), a funnel (720) is provided at the top of the material guiding assembly (710), and a support rod (730) is provided at the bottom of the material guiding assembly (710); The material guiding assembly (710) comprises a curved tube (711), the upper end of the curved tube (711) is integrally formed with an inclined tube (712) arranged to be inclined upward, the bottom end of the funnel (720) is connected to the top of the inclined tube (712), and the support rod (730) is located at the bottom of the inclined tube (712).

10. The quartz sand impurity removal and dehydroxylation equipment according to claim 9, characterized in that: It also includes a ventilation pipe (300), an air suction mechanism (400) and a glass cover (600); The ventilation pipe (300) is in communication with the connecting pipe (213); and the ventilation pipe (300) is in communication with the atmospheric gas; A glass cover (600) is provided at the upper end of each of the glass tubes (210); the glass cover (600) comprises a glass cover body (610) sleeved on the top end of the glass tube (210); the glass cover body (610) is in the shape of a semi-hollow sphere; and an air outlet pipe (620) is connected to the center of the top of the glass cover body (610); The air suction mechanism (400) cooperates with an external suction fan to perform suction operations, and the air suction mechanism (400) is located above the vertical high-temperature furnace (100); the air suction mechanism (400) includes an air suction pipe (410) connected to the external suction fan, and the bottom of the air suction pipe (410) is connected to a plurality of arc-shaped pipes (420), and the arc-shaped pipes (420) correspond one-to-one to a plurality of air outlet pipes (620).

Images