Crystal quartz sand making method without magnetic separation, flotation and acid washing

Abstract

The application provides a method for preparing crystal quartz sand without magnetic separation, flotation and pickling, which uses artificial quartz crystal as raw material to prepare sand, and the purity of the artificial quartz crystal reaches 4N8 or above; the whole sand preparation process can be divided into four procedures of once water quenching, twice water quenching, roller and screening; in the sand preparation process, water quenching is used to replace crushing, so that the pollution caused by crushing is avoided; synthetic quartz roller is used to replace steel roller, so that the metal pollution caused by the steel roller is avoided; Teflon plate is used as lining, so that the pollution caused by the friction between the quartz sand and the steel inner wall is avoided; nylon screen is used to replace stainless steel screen, so that the pollution caused by the friction between the quartz sand and the stainless steel screen is avoided; the application effectively avoids the problem of introducing other impurities in the processing process, realizes sand preparation without pickling, magnetic separation and flotation, and also avoids the problems of acid pollution and difficult treatment of acid liquid in the sand preparation process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quartz sand processing, and particularly relates to a crystal quartz sand preparation method without magnetic separation, flotation and pickling. BACKGROUND

[0002] High-purity quartz sand is a kind of pure mineral resource, and its main component is silicon dioxide, and a small amount of aluminum oxide, calcium, magnesium and the like. Since the high-purity quartz sand is highly pure and chemically stable, it is mainly applied in the integrated circuit (IC) and quartz glass industries. The high-purity quartz sand is a consumable in the semiconductor industry and the photovoltaic industry. In the process of preparing high-purity single crystal silicon, a crucible prepared from the high-purity quartz sand is used to heat raw polycrystalline silicon. The high-purity quartz sand is also a raw material for high-end glass, and is widely applied in many civilian and military fields such as lighting, radar cover, sterilization and disinfection. At present, the traditional preparation method of quartz sand is to prepare quartz sand through the processes of cleaning raw ore, crushing, water quenching, hammering, impact breaking, roller, screening, permanent magnet, pickling, flotation, drying and magnetic separation.

[0003] In the traditional preparation method of quartz sand, no matter what purity of raw material is adopted, the quartz sand raw material is directly contacted with manganese steel, stainless steel and other ferrous alloys throughout the preparation process, and other metal impurities are inevitably mixed, thereby causing pollution of the quartz sand. After the sand is prepared, the impurities in the raw ore and the impurities in the processing process need to be removed through magnetic separation, pickling, flotation and the like. In the pickling process, a large amount of volatile chemicals such as hydrochloric acid, hydrofluoric acid and nitric acid are used, which causes air pollution in the workshop, is not conducive to environmental protection, and after the waste acid is discharged, a complex waste acid treatment process is needed to achieve the purpose of harmless discharge. The recovery and treatment process is complex and high in cost. In the flotation process, a certain amount of organic substances are used, thereby introducing organic impurities. In addition, whether pickling or flotation, a large amount of pure water is used, which causes water consumption and increases the difficulty of sewage treatment. Therefore, the application provides a quartz sand preparation method without magnetic separation, pickling and flotation, and without introducing other impurities in the processing process. SUMMARY

[0004] In view of the problems in the prior art, the application provides a crystal quartz sand preparation method without magnetic separation, pickling and flotation. Through the processes of one-time water quenching, two-time water quenching, roller and screening, synthetic quartz rollers, nylon screen meshes and Teflon plates are effectively used, three process steps of magnetic separation, flotation and pickling are avoided, and the problem that the quartz sand is contacted with traditional steel materials and thereby other impurity elements are introduced is solved.

[0005] The application provides a crystal quartz sand preparation method without magnetic separation, pickling and flotation, and the method comprises the following steps.

[0006] (1) preparing a synthetic quartz crystal;

[0007] (2) first water quenching: the artificial quartz crystal is put into a heating furnace, and after heat preservation for 30 min, water quenching is carried out, and after water quenching, quartz blocks with a particle size of less than 5 cm are obtained, and the quartz blocks containing iron wires are removed and dried;

[0008] (3) second water quenching: the quartz blocks are put into a heating furnace, and after heat preservation for 20 min, water quenching is carried out, and after water quenching, quartz particles with a particle size of less than 5 mm are obtained, and dried;

[0009] (4) sand making by roller: the quartz particles are put into a roller machine to make quartz sand, the roller machine adopts synthetic quartz rollers, and the part of the roller machine contacting the quartz particles is lined with a Teflon plate;

[0010] (5) screening: the quartz sand is put into a vibrating screen for screening, the vibrating screen adopts a nylon screen mesh, and the part of the inner layer of the vibrating screen contacting the quartz sand is attached to a Teflon plate, and after screening, high-purity quartz sand is obtained.

[0011] Preferably, the purity of the artificial quartz crystal in step (1) reaches 4N8 and above;

[0012] Preferably, the heating furnace in step (2) is a box-type resistance heating furnace, and the temperature in the furnace is 200-300℃;

[0013] Preferably, the water quenching in steps (2) and (3) both uses pure water with a temperature of <80℃;

[0014] Preferably, the heating furnace in step (3) is a quartz tube rotary heating furnace, and the temperature in the furnace is 1145-1155℃;

[0015] Preferably, the synthetic quartz rollers in step (4) adopt synthetic quartz with a purity of 6N or above;

[0016] Preferably, the thickness of the Teflon plate is 1mm;

[0017] Preferably, the particle size of the nylon screen mesh in step (5) is 100-200 mesh.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] 1. In the sand making process of the present application, water quenching is used instead of crushing to eliminate the pollution caused by crushing; synthetic quartz rollers are used instead of steel rollers to eliminate the metal pollution caused by steel rollers; Teflon plates are used for lining to eliminate the pollution caused by the friction between quartz sand and steel inner wall; nylon screen meshes are used instead of stainless steel screen meshes to eliminate the pollution caused by the friction between quartz sand and stainless steel screen meshes; the above methods effectively avoid the problem of introducing other impurities in the processing process.

[0020] 2. This invention, while ensuring the production of high-purity quartz sand, can eliminate the magnetic separation, flotation, and acid washing processes in the sand making process, thus simplifying the process flow.

[0021] By eliminating the flotation process, the addition of organic substances such as kerosene and sodium petroleum sulfonate can be avoided, making the sand production line more environmentally friendly and increasing the yield.

[0022] Eliminating the magnetic separation process prevents the introduction of other metallic impurities and avoids contamination from foreign impurities such as iron.

[0023] By eliminating the pickling process, volatile acids such as hydrochloric acid, hydrofluoric acid, and nitric acid are no longer used, thus eliminating the environmental pollution and safety risks associated with pickling. Furthermore, since approximately 10 tons of pure water are required for each ton of sand pickling process, eliminating pickling significantly reduces water consumption. Detailed Implementation

[0024] To better understand the content of this invention, specific embodiments will be used to further illustrate the invention below. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps; however, the scope of protection of this invention is not limited to the following embodiments.

[0025] This invention discloses a method for producing crystal quartz sand without magnetic separation, flotation, or acid washing. It utilizes artificial quartz crystals as raw material, with the artificial quartz crystals achieving a purity of 4N8 or higher. The entire sand-making process can be divided into four steps: primary water quenching, secondary water quenching, roller quenching, and screening. Anti-pollution measures are implemented for these four steps to prevent impurities from entering during processing, achieving sand production without acid washing, magnetic separation, or flotation. This also eliminates the problems of acid pollution and difficult-to-treat acid solutions during the sand-making process. The sand-making workshop undergoes simple dust control measures and uses ventilation devices with air filtration.

[0026] This invention discloses a method for producing crystal quartz sand without magnetic separation, flotation, or acid washing, specifically comprising the following steps:

[0027] (1) Preparation of artificial quartz crystals: Based on the composition of the final high-purity quartz sand, select artificial quartz crystals that match it and have a purity of 4N8 or higher.

[0028] (2) First water quenching: The selected artificial quartz crystals are placed in a box-type resistance heating furnace at a temperature of 200-300℃ and kept at that temperature for 30 minutes (the temperature change in the furnace is controlled within ±1℃). Then, pure water is used for water quenching. The temperature of the pure water is <80℃. The particle size of the quartz blocks after water quenching is within 5cm. Quartz blocks containing iron wire are removed, and quartz blocks without iron wire are air-dried naturally.

[0029] (3) secondary water quenching: the dried quartz block is put into a quartz tube rotary heating furnace with a temperature of 1145-1155℃, and after 20 minutes of heat preservation, the quartz block is water quenched with pure water, and then naturally dried; the temperature of the pure water is <80℃, the particle size of the quartz particles after water quenching is within 5mm, and the whole body is white;

[0030] (4) sand making by a pair of rollers: the quartz particles after secondary water quenching are put into a pair of rollers for sand making, the pair of rollers are all made of synthetic quartz rollers, and the purity of the synthetic quartz is more than 6N; and the part of the pair of rollers that contacts the quartz particles is all lined with 100% new Teflon plate, so as to avoid the contact between the quartz particles and iron; the thickness of the Teflon plate is preferably 1mm;

[0031] (5) screening: the quartz sand after the pair of rollers is put into a vibrating screen for screening, the vibrating screen is provided with a nylon screen with a particle size of 100-200 mesh, and the part of the inner layer of the vibrating screen that contacts the quartz sand is attached with a Teflon plate, and the thickness of the Teflon plate is preferably 1mm; and high-purity quartz sand is obtained after screening.

[0032] In the present application, the high-purity quartz sand obtained is subjected to component detection by ICP-MS; the quartz sand is made of artificial quartz crystals, the impurity content in the crystals is low, the inclusions are few, and the crystals are fully transparent; and in the whole sand making process, water quenching is used instead of crushing, so as to eliminate the pollution caused by crushing; synthetic quartz rollers are used instead of steel rollers, so as to eliminate the metal pollution caused by the steel rollers; the Teflon plate is used for lining, so as to eliminate the pollution caused by the friction between the quartz sand and the steel inner wall; the nylon screen is used instead of the stainless steel screen, so as to eliminate the pollution caused by the friction between the quartz sand and the stainless steel screen, and the foregoing sand making method effectively avoids the problem of introducing other impurities in the processing process, so that the magnetic separation, flotation and acid washing processes in the sand making process are omitted, and the high-purity quartz sand can still be obtained.

[0033] The present application will be further understood through specific examples:

[0034] Example 1

[0035] (1) preparation of artificial quartz crystals: 10kg of Z0° artificial quartz crystals are selected, the thickness of the Z direction is 25±5mm, the length of the Y direction is 210mm, and the total width of the X direction is 60-70mm, and the component detection of the artificial quartz crystals is shown in Table 1 (unit: ppm);

[0036] Table 1

[0037] No. Impurity element Content No. Impurity element Content 1 Li 0.66 8 Ti 0 2 Na 0.48 9 Cr 0 3 K 0.09 10 Ni 0 4 Al 6.36 11 Cu 0 5 Fe 0.12 12 Co 0 6 Ca 0.13 13 B 0 7 Mn 0 14 Mg 0.09

[0038] (2) first water quenching: the selected artificial quartz crystal is placed into a box type resistance heating furnace with a temperature of 300°C, and after heat preservation for 30 min (the temperature change in the furnace is controlled within ±1°C), water quenching is performed by using pure water at 25°C, the particle size of the quartz block after water quenching is about 5 cm, the quartz block containing iron wires is removed, and then the quartz block without iron wires is naturally dried to obtain 9.1 kg of quartz blocks;

[0039] (3) second water quenching: the dried quartz block is placed into a quartz tube rotary heating furnace with a temperature of 1155°C, and after heat preservation for 20 min, water quenching is performed by using pure water at 25°C, the particle size of the quartz particles after water quenching is about 5 mm, and the whole body is white, the obtained quartz particles are naturally dried, and the weight is 9 kg;

[0040] (4) roll-to-roll sanding: the quartz particles after the second water quenching are placed into a roll-to-roll machine for sanding, the roll-to-roll machine is entirely provided with synthetic quartz rollers with a diameter of 200 mm and a length of 300 mm, and the part of the roll-to-roll machine that contacts the quartz particles is entirely attached with a Teflon plate, and 8.82 kg of quartz sand is obtained;

[0041] (5) screening: the quartz sand after the roll-to-roll sanding is placed into a linear vibration screen for screening, the linear vibration screen is provided with a nylon screen mesh with a particle size of 100-200 mesh, and the part of the linear vibration screen that contacts the quartz sand is entirely attached with a Teflon plate, and high-purity quartz sand is obtained after screening; the quartz sand with a particle size of less than 100 mesh is 6.1 kg, the quartz sand with a particle size of 100-200 mesh is 1.9 kg, and the quartz sand with a particle size of more than 200 mesh is 0.73 kg;

[0042] The 100-200 mesh high-purity quartz sand prepared in Example 1 is detected for impurity content by using an ICP-MS method, and the detection results are shown in Table 2 (unit: ppm):

[0043] Table 2

[0044] No. Impurity element Content No. Impurity element Content 1 Li 0.64 8 Ti 0 2 Na 0.52 9 Cr 0 3 K 0.08 10 Ni 0 4 Al 6.71 11 Cu 0 5 Fe 0.22 12 Co 0 6 Ca 0.39 13 B 0 7 Mn 0 14 Mg 0.12

[0045] As can be seen from Table 1 and Table 2, no other impurity elements are introduced in the process of preparing high-purity quartz sand by using artificial quartz crystals, that is, the crystal quartz sand preparation method of the present application does not introduce other impurities, and can avoid the pollution of high-purity quartz sand.

[0046] Example 2

[0047] (1) preparation of artificial quartz crystal: 10 kg of Z0° artificial quartz crystal is selected, the Z-direction thickness is 25±5 mm, the Y-direction length is 210 mm, and the X-direction total width is 60-70 mm, and the composition of the artificial quartz crystal is detected as shown in Table 1 (same as Example 1);

[0048] (2) first water quenching: the selected artificial quartz crystal is placed into a box type resistance heating furnace with a temperature of 200°C, and after heat preservation for 30 min (the temperature change in the furnace is controlled within ±1°C), water quenching is performed using pure water at 25°C, and the particle size of the quartz block after water quenching is about 5 cm. The quartz block containing iron wires is removed, and the quartz block without iron wires is naturally dried to obtain 8.6 kg of quartz block;

[0049] (3) second water quenching: the dried quartz block is placed into a quartz tube rotary heating furnace with a temperature of 1145°C, and after heat preservation for 20 min, water quenching is performed using pure water at 25°C. The particle size of the quartz particles after water quenching is about 5 mm, and the whole body is white. The obtained quartz particles are naturally dried, and the weight is 8.55 kg;

[0050] (4) roll-to-roll sanding: the quartz particles after the second water quenching are placed into a roll-to-roll machine for sanding. The roll-to-roll machine is entirely made of synthetic quartz rollers with a diameter of 200 mm and a length of 300 mm. The part of the roll-to-roll machine that contacts the quartz particles is entirely attached with Teflon plates, and 8.4 kg of quartz sand is obtained;

[0051] (5) screening: the quartz sand after roll-to-roll sanding is placed into a linear vibration screen for screening. The linear vibration screen is made of nylon screen mesh with a particle size of 100-200 mesh, and the part that contacts the quartz sand is entirely attached with Teflon plates. After screening, high-purity quartz sand is obtained. The quartz sand with a particle size of less than 100 mesh is 5.7 kg, the quartz sand with a particle size of 100-200 mesh is 2.0 kg, and the quartz sand with a particle size of more than 200 mesh is 0.6 kg;

[0052] The impurity content of the 100-200 mesh high-purity quartz sand prepared in Example 2 is detected by ICP-MS method, and the detection results are shown in Table 3 (unit: ppm):

[0053] Table 3

[0054] No. Impurity element Content No. Impurity element Content 1 Li 0.66 8 Ti 0 2 Na 0.56 9 Cr 0 3 K 0.1 10 Ni 0 4 Al 6.54 11 Cu 0 5 Fe 0.2 12 Co 0 6 Ca 0.17 13 B 0 7 Mn 0 14 Mg 0.11

[0055] As can be seen from the comparison between Table 1 and Table 3, no other impurity elements are introduced in the process of preparing high-purity quartz sand from artificial quartz crystal, i.e., the crystal quartz sand preparation method of the present application without magnetic separation, flotation and acid washing does not introduce other impurities, and can avoid pollution to high-purity quartz sand.

[0056] Comparative example (using traditional sand preparation process)

[0057] (1) preparation of artificial quartz crystal: 10 kg of Z0° artificial quartz crystal is selected, with a Z-direction thickness of 25±5 mm, a Y-direction length of 210 mm, and an X-direction total width of 60-70 mm. The composition of the artificial quartz crystal is detected as shown in Table 1 (same as Example 1);

[0058] (2) Breaking: the breaking machine is made of high manganese steel, and the artificial quartz crystal is broken into crystal blocks with a volume of ≤8 mm, and 9.9 kg of crystal blocks are obtained;

[0059] (3) High-temperature water quenching: the crystal blocks are water quenched at 1145℃, and the circulating water temperature is 25℃;

[0060] (4) Hammer breaking: the hammer breaking machine is made of high manganese steel, and the crystal blocks after water quenching are broken by hammering, so that the particle size of the crystal blocks becomes quartz sand with a particle size of ≤3 mm;

[0061] (5) Impact breaking and roller breaking: the quartz sand after hammer breaking is passed through an impact breaking and roller breaking machine, and is broken into quartz sand with a finer particle size;

[0062] (6) Acid pickling: a mixed acid of hydrochloric acid and hydrofluoric acid is used for acid pickling, and the acid is of analytical purity, 0.132 kg of 37% concentrated hydrochloric acid, 0.03 kg of 70% concentrated hydrofluoric acid, and 0.438 kg of ultrapure water with an electrical conductivity of <5 us / mm are added per kg of sand; the acid pickling time is 24 h, and the acid pickling temperature is 60℃;

[0063] (7) Washing: after the acid solution is discharged, pure water with an electrical conductivity of 5 us / mm is used for washing until the electrical conductivity of the water reaches within 10 us / mm;

[0064] (8) Drying: the quartz sand after acid pickling and washing is placed in a rotary furnace for drying, the drying temperature is 1000℃, and the quartz sand stays in the tube for 15 min;

[0065] (9) Screening and detection: after the high-purity quartz sand with a particle size of 100-200 is screened out by using a screen, ICP-MS composition detection is performed, as shown in Table 4;

[0066] Table 4

[0067] No. Impurity element Content No. Impurity element Content 1 Li 0.63 8 Ti 0 2 Na 0.46 9 Cr 0 3 K 0.09 10 Ni 0 4 Al 6.38 11 Cu 0 5 Fe 0.12 12 Co 0 6 Ca 0.17 13 B 0 7 Mn 0 14 Mg 0.10

[0068] As can be seen from Example 1, Example 2 and the comparative example, by using the same artificial quartz crystal under the same conditions, the impurity elements in the high-purity quartz sand prepared by the new process of the application and the traditional process are not much different; therefore, when artificial quartz crystal with a purity of 4N8 or above is used to prepare sand, the steps of magnetic separation, flotation, acid pickling and the like are omitted in the application, other impurities are not introduced, the purity of the high-purity quartz sand can be ensured, and the process flow is more simplified and easy to operate.

[0069] The above merely describes preferred embodiments of the present application, and the present application can have other forms of embodiments according to the above preparation method, which are not listed one by one. Therefore, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application without departing from the technical solution range of the present application, all still belong to the technical solution range of the present application.

Claims

1. A method for producing crystal quartz sand without magnetic separation, flotation, or acid washing, characterized in that, Includes the following steps: (1) Prepare artificial quartz crystals with a purity of 4N8 or higher; (2) First water quenching: The artificial quartz crystal is placed in a box-type resistance heating furnace. The furnace temperature is 200-300℃. After holding for 30 minutes, it is water quenched. After water quenching, quartz blocks with a particle size of less than 5cm are obtained. Quartz blocks containing iron wire are removed and dried. (3) Secondary water quenching: The quartz block is placed in a quartz tube rotary heating furnace. The furnace temperature is 1145-1155℃. After holding for 20 minutes, water quenching is performed. After water quenching, quartz particles with a particle size of less than 5mm are obtained and then dried. (4) Roller sand making: Quartz particles are put into the roller mill to make quartz sand. The roller mill uses synthetic quartz rollers, and the part of the roller mill that comes into contact with the quartz particles is lined with Teflon plates. (5) Screening: The quartz sand is put into a vibrating screen for screening. The vibrating screen is made of nylon screen mesh, and the part of the inner layer of the vibrating screen that contacts the quartz sand is attached with Teflon plate. After screening, high-purity quartz sand is obtained. In both steps (2) and (3), pure water with a temperature of <80℃ is used for water quenching.

2. The method for producing crystal quartz sand without magnetic separation, flotation, and acid washing as described in claim 1, characterized in that, The synthetic quartz used in step (4) has a purity of 6N or higher.

3. The method for producing crystal quartz sand without magnetic separation, flotation, and acid washing as described in claim 1, characterized in that, The Teflon sheet has a thickness of 1 mm.

4. The method for producing crystal quartz sand without magnetic separation, flotation, and acid washing as described in claim 1, characterized in that, In step (5), the particle size of the nylon screen is 100-200 mesh.