Process and system for preparing ultra-pure quartz sand from quartz material

Abstract

The invention relates to the technical field of quartz sand preparation processes, and particularly discloses a process and system for preparing ultra-pure quartz sand from a quartz material, and the process comprises the following steps: pretreatment, decontamination, soaking, rinsing, growth, crushing, acid pickling, drying and warehousing. The invention solves the problem that the high-purity quartz sand cannot be produced in China at present, so that the fields of photovoltaic quartz sand, semiconductor quartz sand, high-end optics and the like can only depend on import. According to the preparation technology, impurities and inclusions in the quartz ore can be removed through a crystal growth method, the technology is simple, energy consumption is low, the purity of the quartz ore product is high (4N8 or above), and mass production is easy to achieve.

Description

Technical Field

[0001] The invention belongs to the technical field of quartz sand preparation technology, and specifically relates to a process and system for preparing ultra-high purity quartz sand by using quartz material. Background Art

[0002] Silicon dioxide is an inorganic substance with the chemical formula SiO2. Silicon atoms and oxygen atoms are arranged in a long-range orderly manner to form crystalline silicon dioxide, and short-range orderly or long-range disordered arrangements form amorphous silicon dioxide. In silicon dioxide crystals, silicon atoms are located at the center of a regular tetrahedron, and four oxygen atoms are located at the four vertices of the regular tetrahedron. Many such tetrahedrons are connected by oxygen atoms at the vertices, and each oxygen atom is shared by two tetrahedrons, that is, each oxygen atom is combined with two silicon atoms. The simplest formula of silicon dioxide is SiO2, but SiO2 does not represent a simple molecule (it only represents the ratio of the number of silicon and oxygen atoms in the silicon dioxide crystal). Pure natural silicon dioxide crystals are a hard, brittle, insoluble, colorless and transparent solid, commonly used in the manufacture of optical instruments, etc.

[0003] The quartz industry is a materials and products industry with silicon dioxide as the main component. Due to its very stable physical and chemical properties, it is widely used in high-tech fields such as new energy solar energy, optical fibers, information technology, lasers, aerospace, national defense and military industry. It is an irreplaceable important raw material for high-end equipment manufacturing.

[0004] At present, the process technologies for preparing high-purity quartz sand include physical method, chemical method, physical and chemical method, etc. Unimin uses quartz produced in North Carolina, USA, and produces high-purity quartz sand through specific process treatment and chemical purification, which is at the world's leading level (specific technology is not disclosed to the public); the quartz products of Norway's TQC company are mainly used to meet the standard requirements of the semiconductor and solar energy industries, as well as to provide tailor-made products for the optical and lighting industries. However, with the continuous development of the market, the demand for high-purity quartz sand with a purity higher than 4N5 and above is increasing, which has led to the current output of high-purity quartz sand, which has greatly hindered the development of industries such as photovoltaics, chips, and high-end optics. Based on this, the high-purity quartz sand industry is in urgent need of technological breakthroughs.

[0005] The existing quartz sand technology can only solve the mass production of quartz sand below 4N. The selection of 3N5 quartz sand with higher purity can reach 4N3 purity in laboratory tests, but it is difficult to reach 5N and above purity, which cannot meet the needs of domestic semiconductor, photovoltaic, and high-end optical fields. The ultra-high purity quartz sand prepared by silicon tetrachloride dry method is too expensive, and the size cannot meet the needs of high-end customers.

[0006] For example, the prior art CN110510620A discloses a "method for purifying high-purity quartz sand tailings", wherein the high-purity quartz sand tailings are purified into high-purity quartz sand of more than 99.9% by processes including grinding, ball mill screening, strong magnetic separation, acid leaching, calcination, water quenching, secondary acid leaching, and cleaning, which cannot meet the purity requirements of photovoltaic quartz sand above 4N8. CN112624124 A discloses a "process for preparing high-purity and highly hydrophobic quartz sand", which uses processes such as classification and water washing, crushing and screening, magnetic separation, flotation, acid washing, surface modification, and hydrophobic treatment to prepare vein quartz ore into high-purity and highly hydrophobic quartz sand above 4N2, which also cannot meet the purity requirements of photovoltaic quartz sand above 4N8. CN106917142 A discloses a "method for growing high-purity quartz crystals", which is mainly used to grow bulk quartz crystals and ensure that the impurity content of aluminum Al is less than 15ppm. Summary of the invention

[0007] The object of the present invention is to provide a process and system for preparing ultra-high purity quartz sand using quartz material to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A process for preparing ultra-high purity quartz sand from quartz material comprises the following steps:

[0010] S1. Pretreatment: Select quartz ore and remove the sand, oil and impurities attached to the surface of quartz ore (5-100mm);

[0011] S2, soaking and rinsing: soak the pre-treated quartz ore in mixed acid for 2 to 10 days; then, take it out, put it in a deionized water tank, and rinse it 3 to 5 times to remove impurities on the surface of the quartz ore;

[0012] The mixed acid includes nitric acid and hydrochloric acid, the ratio of nitric acid to hydrochloric acid is 3-0.5, the concentration of nitric acid is 10%-25%, the concentration of hydrochloric acid is 5%-15%, and both nitric acid and hydrochloric acid are analytically pure;

[0013] S3, growth: the rinsed quartz ore is placed in a high-pressure reactor (the maximum capacity of the quartz ore is 1 / 2 to 2 / 3 of the volume of the autoclave), and then a mixture of a 0.5-5M NaOH solution and a 0.3-3M Na2CO3 solution is added to the autoclave;

[0014] Put a rack in the autoclave, hang a plurality of 300-600 seed wafers on the rack, control the height of the rack to be ≥ the liquid level, and close the autoclave;

[0015] Heat the autoclave to 350-400°C, control the bottom temperature of the autoclave to be 20-30°C higher than the top temperature, and at the same time, control the pressure in the autoclave to be 70-150MPa, react, stop the furnace, cool to room temperature, and obtain high-purity quartz ore (crystal); open the autoclave, take out the rack, and take out the crystal;

[0016] In addition, for the autoclave, heat to 350-400°C at a rate of 1-5°C / min and keep warm for 2-15 days;

[0017] Among them, the purity of high-purity quartz ore is above 3N.

[0018] S4, crushing: crushing and sieving the obtained crystal to obtain 80-230 μm crystal powder;

[0019] S5, pickling: put the crystal powder into the pickling tank, soak it for 0.5 to 2 days under the condition of bubbling or stirring with compressed air; then take it out, put it in the deionized water tank, rinse it 3-5 times to remove impurities on the surface of the powder;

[0020] S6, drying: the rinsed crystal powder is passed through a quartz tube into an oven and dried at 120-150°C; then it is discharged to a magnetic separation device through a quartz tube, and after magnetic separation, the powder is bagged, tested and stored;

[0021] Among them, according to actual needs, powders with a particle size of 80-200μm are screened for bagging, and purity and inclusion density tests are carried out, and powders that meet product requirements are put into storage.

[0022] A system for preparing ultra-high purity quartz sand from quartz material, comprising a cleaning tank, a soaking tank, a high-pressure reactor, a crusher, a screening device, a pickling tank and an oven, wherein the cleaning tank is arranged at the front side of the station of the soaking tank, the high-pressure reactor is arranged at the rear side of the station of the soaking tank, and a first deionized water tank is arranged between the soaking tank and the high-pressure reactor; the crusher is arranged at the rear side of the station of the high-pressure reactor, the screening device is arranged at the rear side of the station of the high-pressure reactor, the pickling tank is arranged at the rear side of the station of the screening device, the oven is arranged at the rear side of the station of the pickling tank, and a second deionized water tank is arranged between the pickling tank and the oven;

[0023] A continuous passage for preparing ultra-high purity quartz sand from quartz ore is formed between the cleaning tank, the soaking tank, the first deionized water tank, the high-pressure reactor, the crusher, the screening device, the pickling tank, the second deionized water tank and the oven; a rack is arranged in the high-pressure reactor, the rack includes a bracket and a partition, and a pressure detector and a temperature detector are arranged on the inner wall of the high-pressure reactor for regrowth of silicon dioxide crystals.

[0024] Preferably, the cleaning tank is provided with a detergent inlet for removing mud, sand, oil and other impurities attached to the surface of the quartz raw material.

[0025] Preferably, the soaking tank is provided with a mixed acid inlet.

[0026] Preferably, the screening device is used to screen the crystal powder.

[0027] Preferably, a stirring mechanism is provided in the pickling tank or a compressed air pipe is provided in the pickling tank, and air jets are evenly distributed on the compressed air pipe, thereby increasing the contact area between the crystal powder and the acid and improving the quality and efficiency of impurity removal; the pickling tank is a pickling tank made of strong acid-resistant material and is used for pickling the crystal powder.

[0028] Preferably, the oven is used to dry the rinsed crystal powder to facilitate subsequent storage and transportation.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention solves the problem that the country cannot produce high-purity quartz sand, which has led to the quartz sand for photovoltaics, semiconductors, high-end optics and other fields relying on imports. The preparation process can remove impurities and inclusions in quartz ore by the method of crystal growth. The process is simple, the energy consumption is low, the quartz ore product is high in purity (4N8 or above), and it is easy to achieve mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0032] Figure 2 This is a schematic diagram of the station allocation of the preparation device of the present invention;

[0033] Figure 3 This is a schematic diagram of the structure of the rack of the present invention;

[0034] Figure 4 It is a schematic diagram of the stirring type and the air compression pipe opening method in the pickling tank of the present invention;

[0035] Figure 5 This is an electron microscope image of the first liquid-rich gas-liquid two-phase brine inclusion of the present invention;

[0036] Figure 6 This is an electron microscope image of the second liquid-rich gas-liquid two-phase brine inclusion of the present invention;

[0037] Figure 7 This is an electron microscope image of the third liquid-rich gas-liquid two-phase brine inclusion of the present invention;

[0038] Figure 8 This is an electron microscope image of the fourth liquid-rich gas-liquid two-phase brine inclusion of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] See also Figure 1 - Figure 8 As shown, a process for preparing ultra-high purity quartz sand from quartz material comprises the following steps:

[0042] Pretreatment: remove impurities such as sand, oil and so on attached to the surface of quartz ore 50mm thick;

[0043] Soaking and rinsing: Soak the pre-treated quartz ore in mixed acid for 7 days; then take it out, put it in a deionized water tank, and rinse it 5 times to remove impurities on the surface of the quartz ore;

[0044] The mixed acid includes nitric acid and hydrochloric acid, the ratio between nitric acid and hydrochloric acid is 1.5, the concentration of nitric acid is 20%, the concentration of hydrochloric acid is 10%, and both nitric acid and hydrochloric acid are analytically pure;

[0045] Growth: Place the rinsed quartz ore in a high-pressure reactor (the maximum capacity of the quartz ore is 1 / 2 to 2 / 3 of the volume of the autoclave), then add a mixture of a 1M NaOH solution and a 0.3 Na2CO3 solution into the autoclave;

[0046] Put a rack in the autoclave, hang a plurality of 400 seed wafers on the rack, control the rack height ≥ liquid level, and close the autoclave;

[0047] Heat the autoclave to 350-400°C, control the bottom temperature of the autoclave to be 20-30°C higher than the top temperature, and at the same time, control the pressure in the autoclave to be 120MPa, react, stop the furnace, cool to room temperature, and obtain high-purity quartz ore (crystal); open the autoclave, take out the rack, and take out the crystal;

[0048] In addition, for the autoclave, heat to 350-400°C at a rate of 1-5°C / min and keep it for 15 days;

[0049] Among them, the purity of high-purity quartz ore is above 3N.

[0050] Crushing: crush and sieve the obtained crystal to obtain 200μm crystal powder;

[0051] Pickling: Put the crystal powder into the pickling tank and soak it for 2 days under the condition of bubbling or stirring with compressed air; then take it out and put it in the deionized water tank, rinse it 5 times to remove impurities on the surface of the powder;

[0052] Drying: The rinsed crystal powder is passed through a quartz tube into an oven and dried at 120°C; then it is discharged through a quartz tube into a magnetic separation device. After magnetic separation, the powder is bagged, tested and stored;

[0053] Among them, according to actual needs, powders with a particle size of 200μm can be screened for bagging, and purity and inclusion density tests can be carried out, and powders that meet product requirements can be put into storage;

[0054] When conducting purity and inclusion density tests, samples are randomly taken from the bagged high-purity quartz crystals to ensure the representativeness of the samples.

[0055] Purity test: Select an appropriate test method (such as I CP-MS, GDMS or EMPA) according to laboratory conditions to test the purity of the sample.

[0056] Inclusion density detection: Use polarized light microscopy observation and counting or image processing technology to observe and measure the inclusions in the sample and estimate their density.

[0057] Data processing and analysis: Organize and analyze the test results to evaluate whether the purity and inclusion density of the samples meet relevant standards or customer requirements.

[0058] The high-pressure reactor used in the present invention is a common reactor on the market, and a pressure detector and a temperature detector are arranged on the inner wall of the high-pressure reactor for the regrowth of silicon dioxide crystals. The inner diameter size of the reactor used in the present invention is 330 or other models, specifically a Zhongyuan Special Steel reactor.

[0059] The inclusion density detection and data processing and analysis of the present invention are specifically as follows:

[0060] Microscopic characteristics of inclusions: Description of sand thin sections: The sand thin sections under the microscope are clean, quartz grains with clear boundaries are rare, and inclusions are rare.

[0061] Number and distribution of inclusions: Inclusions are randomly distributed in the sand slices, and there are very few inclusions. On average, only 1-2 inclusions are seen in 10 random fields (50x magnification)

[0062] Inclusion morphology: The inclusion morphology is mainly nearly circular, oval and irregular.

[0063] Inclusion size: The largest inclusion is 9.66um and the smallest is 4.07um. (50x microscope)

[0064] Inclusion phase: Under a 50x microscope, pure liquid water inclusions and liquid-rich two-phase inclusions are mainly visible, among which liquid-rich gas-liquid two-phase brine inclusions are the most numerous.

[0065] Inclusion type: Pure liquid water inclusions and liquid-rich gas-liquid two-phase NaC1-H20 inclusions can be seen in the sand thin sections, among which liquid-rich gas-liquid two-phase brine inclusions are the most numerous.

[0066] Figure 5 On the left is a 6.97um pure liquid water inclusion. On the right are three inclusions with the largest size of 7.86u, all of which are liquid-rich gas-liquid two-phase brine inclusions.

[0067] Figure 6 On the left, two liquid-rich gas-liquid brine inclusions are shown, with particle sizes of 4.07um and 9.35um respectively. On the right, a 7.06um nearly round gas-liquid two-phase brine inclusion is shown.

[0068] Figure 7 The left picture shows two nearly circular liquid-rich gas-liquid brine inclusions. The right picture shows a 9.66um liquid-rich gas-liquid two-phase brine inclusion. Figure 8 A 5.20um liquid-rich two-phase brine inclusion was seen in the middle, which was irregular in shape.

[0069] A system for preparing ultra-high purity quartz sand from quartz material: comprising a cleaning tank, a soaking tank, a high-pressure reactor, a crusher, a screening device, a pickling tank and an oven, wherein the cleaning tank is arranged at the front side of the soaking tank, the high-pressure reactor is arranged at the rear side of the soaking tank, and a first deionized water tank is arranged between the soaking tank and the high-pressure reactor; the crusher is arranged at the rear side of the high-pressure reactor, the screening device is arranged at the rear side of the high-pressure reactor, the pickling tank is arranged at the rear side of the screening device, the oven is arranged at the rear side of the pickling tank, and a second deionized water tank is arranged between the pickling tank and the oven;

[0070] A continuous passage for preparing ultra-high purity quartz sand from quartz ore is formed between the cleaning tank, the soaking tank, the first deionized water tank, the high-pressure reactor, the crusher, the screening device, the pickling tank, the second deionized water tank and the oven; a rack is arranged in the high-pressure reactor, the rack includes a bracket and a partition, and a pressure detector and a temperature detector are arranged on the inner wall of the high-pressure reactor for regrowth of silicon dioxide crystals.

[0071] The cleaning tank is provided with a detergent inlet for removing mud, sand, oil and impurities attached to the surface of the quartz raw material. The soaking tank is provided with a mixed acid inlet, a crusher for crushing the crystal, a screening device for screening the crystal powder, a stirring mechanism is provided in the pickling tank or a compressed air pipe is provided in the pickling tank, and air jets are evenly distributed on the compressed air pipe, so as to increase the contact area between the crystal powder and the acid and improve the quality and efficiency of impurity removal; the pickling tank is a pickling tank made of strong acid-resistant material and is used for pickling the crystal powder. The oven is used to dry the rinsed crystal powder for subsequent storage and transportation.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing ultra-high purity quartz sand from quartz material, characterized in that: The following steps are involved: S1. Pretreatment: Select quartz ore and remove the sand, oil and impurities attached to the surface of quartz ore (5-100mm); S2, soaking and rinsing: soak the pre-treated quartz ore in mixed acid for 2 to 10 days; then, take it out, put it in a deionized water tank, and rinse it 3 to 5 times to remove impurities on the surface of the quartz ore; The mixed acid includes nitric acid and hydrochloric acid, the ratio of nitric acid to hydrochloric acid is 3-0.5, the concentration of nitric acid is 10%-25%, the concentration of hydrochloric acid is 5%-15%, and both nitric acid and hydrochloric acid are analytically pure; S3, growth: the rinsed quartz ore is placed in a high-pressure reactor (the maximum capacity of the quartz ore is 1 / 2 to 2 / 3 of the volume of the autoclave), and then a mixture of a 0.5-5M NaOH solution and a 0.3-3M Na2CO3 solution is added to the autoclave; Put a rack in the autoclave, hang a plurality of 300-600 seed wafers on the rack, control the height of the rack to be ≥ the liquid level, and close the autoclave; Heat the autoclave to 350-400°C, control the bottom temperature of the autoclave to be 20-30°C higher than the top temperature, and at the same time, control the pressure in the autoclave to be 70-150MPa, react, stop the furnace, cool to room temperature, and obtain high-purity quartz ore (crystal); open the autoclave, take out the rack, and take out the crystal; In addition, for the autoclave, heat to 350-400°C at a rate of 1-5°C / min and keep warm for 2-15 days; Among them, the purity of high-purity quartz ore is above 3N. S4, crushing: crushing and sieving the obtained crystal to obtain 80-230 μm crystal powder; S5, pickling: put the crystal powder into the pickling tank, soak it for 0.5 to 2 days under the condition of bubbling or stirring with compressed air; then take it out, put it in the deionized water tank, rinse it 3-5 times to remove impurities on the surface of the powder; S6, drying: the rinsed crystal powder is passed through a quartz tube into an oven and dried at 120-150°C; then it is discharged to a magnetic separation device through a quartz tube, and after magnetic separation, the powder is bagged, tested and stored; Among them, according to actual needs, powders with a particle size of 80-200μm are screened for bagging, and purity and inclusion density tests are carried out, and powders that meet product requirements are put into storage.

2. A system for preparing ultra-high purity quartz sand from quartz material, characterized in that: It comprises a cleaning tank, a soaking tank, a high-pressure reactor, a pulverizer, a screening device, a pickling tank and an oven, wherein the cleaning tank is arranged at the front side of the soaking tank, the high-pressure reactor is arranged at the rear side of the soaking tank, and a first deionized water tank is arranged between the soaking tank and the high-pressure reactor; the pulverizer is arranged at the rear side of the high-pressure reactor, the screening device is arranged at the rear side of the high-pressure reactor, the pickling tank is arranged at the rear side of the screening device, the oven is arranged at the rear side of the pickling tank, and a second deionized water tank is arranged between the pickling tank and the oven; A continuous passage for preparing ultra-high purity quartz sand from quartz ore is formed between the cleaning tank, the soaking tank, the first deionized water tank, the high-pressure reactor, the crusher, the screening device, the pickling tank, the second deionized water tank and the oven; a rack is arranged in the high-pressure reactor, the rack includes a bracket and a partition, and a pressure detector and a temperature detector are arranged on the inner wall of the high-pressure reactor for regrowth of silicon dioxide crystals.

3. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: The cleaning tank is provided with a detergent inlet for removing mud, sand, oil and other impurities attached to the surface of the quartz raw material.

4. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: The soaking tank is provided with a mixed acid inlet.

5. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: The crusher is used to crush the crystal.

6. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: The screening device is used to screen the crystal powder.

7. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: A stirring mechanism is arranged in the pickling tank or a compressed air pipe is arranged in the pickling tank, and air jets are evenly distributed on the compressed air pipe, so as to increase the contact area between the crystal powder and the acid and improve the impurity removal quality and efficiency; the pickling tank is a pickling tank made of strong acid-resistant material and is used for pickling the crystal powder.

8. The system for preparing ultra-high purity quartz sand from quartz material according to claim 2, characterized in that: The oven is used to dry the rinsed crystal powder to facilitate subsequent storage and transportation.

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