Process for producing fused and synthetic quartz sand from spent quartz crucibles and products

Abstract

The application relates to a method for preparing high-purity cristobalite sand and / or high-purity fused quartz glass sand by using waste quartz crucible, which comprises the following steps: 1) crushing and first screening the waste quartz crucible; 2) high-temperature roasting the first screening residue to obtain a mixture material in which a surface crystallization layer containing cristobalite sand is separated from fused quartz glass sand; 3) self-grinding and second screening the mixture material; 4) scrubbing the first crude cristobalite sand, removing the third screening residue by wet screening, taking the third screening residue to obtain high-purity cristobalite sand after treatment, and scrubbing the first fused quartz glass sand, removing the fourth screening residue by wet screening, and taking the fourth screening residue to obtain high-purity fused quartz glass sand after treatment. The application also relates to high-purity cristobalite sand and / or high-purity fused quartz glass sand prepared by using the above method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystal growth, in particular, to a method for preparing high-purity quartz sand or high-purity fused quartz glass sand by using waste quartz crucibles, and also relates to a method for simultaneously preparing high-purity quartz sand and high-purity fused quartz glass sand by using waste quartz crucibles, and high-purity quartz sand or high-purity fused quartz glass sand prepared by the method. BACKGROUND

[0002] The quartz crucible is a quartz glass crucible produced by using high-purity quartz sand with a SiO2 content higher than 99.997%, and is widely used for preparing crystal silicon products, as a key consumable in the new energy and semiconductor industries. In the preparation process of crystal silicon, the inner and outer walls of the high-purity quartz crucible will generate a crystallization layer, which will cause the quartz crucible to break. In the prior art, the broken quartz crucible is generally discarded and treated by stacking or landfill. The cost of stacking or landfill is not only high, but also brings great pressure on the environment and space.

[0003] Quartz has high whiteness, high scattering ability, good extinction effect, corrosion resistance, scratch resistance, and high temperature resistance. In recent years, it has been widely used in precision casting, electronic materials, biological chemical industry, aerospace, etc. At present, the preparation of quartz sand is mainly through high-temperature calcination of quartz ore. High-quality quartz ore is rare in China, and the import price is very high. With the continuous expansion and development of China's high-tech industry, the demand for quartz is also increasing.

[0004] High-purity fused quartz glass sand has high purity and low expansion coefficient, and is an important industrial mineral raw material. It is used in glass, casting, ceramics, fireproof materials, smelting silicon iron, metallurgical flux metallurgical building, chemical industry, plastic, rubber, abrasive, filter material, etc. With the development of China's high-tech industry, there is also a certain demand for high-purity quartz glass sand. SUMMARY

[0005] The present application aims to provide the following solutions:

[0006] 1. A method for preparing high-purity quartz sand by using waste quartz crucibles, wherein the method comprises the following steps:

[0007] 1) crushing and first screening the waste quartz crucibles, removing the first undersize, and taking the first oversize;

[0008] 2) performing high-temperature calcination treatment on the first oversize obtained in step 1) to obtain a mixture material in which the surface crystallization layer containing quartz sand is separated from the fused quartz glass sand;

[0009] 3) performing self-milling and second screening on the mixture obtained in step 2), removing the second screen undersize, and taking the second screen oversize to obtain first quartz sand;

[0010] 4) performing scrubbing on the first quartz sand of step 3), and removing the third screen undersize by wet screening, and taking the third screen oversize to obtain high-purity quartz sand after processing.

[0011] 2. A method for preparing high-purity fused quartz glass sand using waste quartz crucibles, wherein the method comprises the following steps:

[0012] 1) performing crushing and first screening on the waste quartz crucibles, removing the first screen undersize, and taking the first screen oversize;

[0013] 2) performing high-temperature calcination on the first screen oversize obtained in step 1) to obtain a mixture in which a surface crystallization layer containing quartz sand is separated from fused quartz glass sand;

[0014] 3) performing self-milling and second screening on the mixture obtained in step 2), removing the second screen undersize, and taking the second screen oversize to obtain first fused quartz glass sand;

[0015] 4) performing scrubbing on the first fused quartz glass sand of step 3), and removing the fourth screen undersize by wet screening, and taking the fourth screen oversize to obtain high-purity fused quartz glass sand after processing.

[0016] 3. A method for preparing high-purity quartz sand and high-purity fused quartz glass sand using waste quartz crucibles, wherein the method comprises the following steps:

[0017] 1) performing crushing and first screening on the waste quartz crucibles, removing the first screen undersize, and taking the first screen oversize;

[0018] 2) performing high-temperature calcination on the first screen oversize obtained in step 1) to obtain a mixture in which a surface crystallization layer containing quartz sand is separated from fused quartz glass sand;

[0019] 3) performing self-milling and second screening on the mixture obtained in step 2), taking the second screen undersize to obtain first quartz sand, and taking the second screen oversize to obtain first fused quartz glass sand;

[0020] 4) performing scrubbing on the crude first quartz sand of step 3), and removing the third screen undersize by wet screening, and taking the third screen undersize to obtain high-purity quartz sand after processing, and performing scrubbing on the first fused quartz glass sand of step 3), and removing the fourth screen undersize by wet screening, and taking the fourth screen oversize to obtain high-purity fused quartz glass sand after processing.

[0021] 4. The method according to any one of items 1 to 3, wherein,

[0022] The waste quartz crucible is a quartz crucible used in the production of crystalline silicon products by the Czochralski method.

[0023] 5. The method according to any one of items 1 to 3, wherein the waste quartz crucible is crushed to a particle size of less than 10 mm by crushing in step 1).

[0024] Preferably, the crushing in step 1) is carried out using a hammer crusher or a roll crusher.

[0025] 6. The method according to any one of items 1 to 3, wherein

[0026] The first screening is carried out using a screen having a diameter of 0.7 to 0.9 mm, preferably 0.80 to 0.85 mm, further preferably 0.83 mm, and preferably the screen is a square hole screen or a round hole screen.

[0027] 7. The method according to any one of items 1 to 3, wherein

[0028] The calcination treatment in step 2) is carried out at a temperature of 300 to 500°C, and preferably the calcination time is 1 minute or more, preferably 1 minute to 1 hour, further preferably 1 minute to 20 minutes.

[0029] 8. The method according to any one of items 1 to 3, wherein

[0030] The method of step 2) further comprises water cooling the first screening residue after calcination, and recovering the cooled and dried residue as the mixture, and preferably the cooling water is used for the self-milling after impurity removal by precipitation.

[0031] 9. The method according to any one of items 1 to 3, wherein

[0032] The self-milling in step 3) is selected from dry self-milling or wet self-milling, and preferably the self-milling is carried out without grinding balls at a rotation speed of 300 to 500 r / min, further preferably the self-milling time is 1 minute or more, further preferably the self-milling is 1 minute to 30 minutes, further preferably the self-milling is 1 minute to 20 minutes.

[0033] 10. The method according to any one of items 1 to 3, wherein

[0034] The second screening is carried out using a screen having a diameter of 0.1 to 0.2 mm, preferably 0.15 to 0.18 mm, and preferably the screen is a square hole screen or a round hole screen.

[0035] 11. The method according to any one of items 1 to 3, wherein

[0036] The scrubbing in step 4) is performed by ultrasonic scrubbing of the first angular quartz sand or the first fused quartz glass sand obtained in step 3), preferably with an ultrasonic frequency of 10-40 kHz, further preferably with an ultrasonic temperature of 20-80°C, and further preferably for an ultrasonic time of 10-20 min.

[0037] Further preferably, the scrubbing liquid used for the scrubbing is added in an amount of 5-10 times the mass of the first angular quartz sand or the first fused quartz glass sand.

[0038] Further preferably, the scrubbing liquid used for the scrubbing of the first angular quartz sand comprises, by mass fraction: 1-20 parts of glacial acetic acid and 100-200 parts of water; or the scrubbing liquid used for the scrubbing of the first fused quartz glass sand comprises, by mass fraction: 1-20 parts of oxalic acid and 100-200 parts of water.

[0039] 12. The method of any one of items 1-3, wherein the wet screening in step 4) is performed by using a screen with a diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm.

[0040] The wet screening in step 4) is performed by using a screen with a diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm.

[0041] 13. The method of any one of items 1-3, wherein the treatment of the third undersize or the fourth oversize after the wet screening is performed by washing with ultrapure water until the pH of the washing liquid is 7, and by drying to obtain the high-purity angular quartz sand or the high-purity fused quartz glass sand.

[0042] The treatment of the third undersize or the fourth oversize after the wet screening is performed by washing with ultrapure water until the pH of the washing liquid is 7, and by drying to obtain the high-purity angular quartz sand or the high-purity fused quartz glass sand.

[0043] 14. A high-purity angular quartz sand, wherein the average particle size of the high-purity angular quartz sand is less than 0.18 mm, the SiO2 content is 98%-99.9%, and the Ba content is less than 15 mg per kg of the angular quartz sand, and the high-purity angular quartz sand is preferably prepared by the method of any one of items 1, 3-13.

[0044] 15. A high-purity angular quartz sand prepared by the method of any one of items 1, 3-13.

[0045] 16. A high-purity fused quartz glass sand, wherein the average particle size of the high-purity fused quartz glass sand is 0.18-0.83 mm, the SiO2 content is 98%-99.9%, and the Ba content is less than 15 mg per kg of the fused quartz glass sand, and the high-purity fused quartz glass sand is preferably prepared by the method of any one of items 2, 3-13.

[0046] 17. A high-purity fused quartz glass sand prepared by the method of any one of items 2, 3-13.

[0047] 18. A method for preparing high purity cristobalite sand from waste quartz crucible, wherein the method comprises the following steps:

[0048] 1) crushing and fifthly sieving the waste quartz crucible, removing the fifthly undersize, and taking the fifthly oversize;

[0049] 2) subjecting the fifthly oversize obtained in step 1) to high temperature calcination treatment to obtain a mixture of surface crystallization layer containing cristobalite sand and fused quartz glass sand separated;

[0050] 3) subjecting the mixture obtained in step 2) to autogenous grinding and sixthly sieving, removing the sixthly undersize, and taking the sixthly oversize to obtain first crude fused quartz glass sand;

[0051] 4) subjecting the first crude fused quartz glass sand obtained in step 3) to rubbing and drying to obtain second crude fused quartz glass sand;

[0052] 5) subjecting the second crude fused quartz glass sand obtained in step 4) to high temperature crystalline phase conversion to obtain the first crude cristobalite sand;

[0053] 6) obtaining high purity cristobalite sand after subjecting the first crude cristobalite sand obtained in step 5) to acid leaching treatment.

[0054] 19. The method according to item 18, wherein,

[0055] the waste quartz crucible is a quartz crucible used in the production of crystalline silicon products using the Czochralski method.

[0056] 20. The method according to item 18 or 19, wherein the waste quartz crucible is crushed to a particle size of less than 10 mm by crushing in step 1), preferably the crushing in step 1) is carried out using a hammer crusher or a roll crusher.

[0057] 21. The method according to any one of items 18 to 20, wherein,

[0058] the first sieving is carried out using a sieve having a diameter of 0.1-0.3 mm, preferably 0.15-0.25 mm, further preferably 0.18 mm, preferably the sieve is a square hole sieve or a round hole sieve.

[0059] 22. The method according to any one of items 18 to 21, wherein,

[0060] the calcination treatment in step 2) is carried out at a temperature of 300-500 °C, preferably for a period of more than 1 minute, preferably for a period of 1 minute to 1 hour, further preferably for a period of 1 minute to 20 minutes.

[0061] 23. The method according to any one of items 18 to 22, wherein,

[0062] The step 2) of the method further comprises water cooling the first sieve residue after roasting, and recovering the mixture after drying, preferably after removing impurities by precipitation of the cooling water, for the autogenous grinding.

[0063] 24. The method according to any one of items 18-23, wherein,

[0064] The autogenous grinding in step 3) is selected from dry autogenous grinding or wet autogenous grinding, preferably the autogenous grinding is carried out without grinding balls at a rotation speed of 300-500 r / min, further preferably the autogenous grinding time is more than 1 minute, further preferably the autogenous grinding is 1-30 minutes, further preferably the autogenous grinding is 1-20 minutes.

[0065] 25. The method according to any one of items 18-24, wherein,

[0066] The second sieving is carried out using a sieve with a diameter of 0.1-0.3 mm, preferably 0.15-0.25 mm, further preferably 0.15 mm, preferably the sieve is a square hole sieve or a round hole sieve.

[0067] 26. The method according to any one of items 18-25, wherein,

[0068] The scrubbing in step 4) is carried out by ultrasonic scrubbing of the first crude fused quartz glass sand obtained in step 3), preferably the ultrasonic frequency is 10-40 kHz, further preferably the ultrasonic temperature is 20-80 °C, further preferably the ultrasonic time is 10-20 min,

[0069] Further preferably, the amount of the scrubbing liquid used for the scrubbing is 5-10 times the mass of the first crude high-purity quartz sand or the first crude fused quartz glass sand,

[0070] Further preferably, the scrubbing liquid used for the scrubbing of the first crude fused quartz glass sand comprises, by mass fraction: oxalic acid 1-20 parts, water 100-200 parts.

[0071] 27. The method according to any one of items 18-26, wherein,

[0072] The high-temperature crystalline phase conversion in step 5) is carried out using a high-temperature roasting furnace at a temperature of 1470 °C-1700 °C, preferably the roasting time is more than 1 hour, further preferably the roasting time is 1-20 h.

[0073] 28. The method according to any one of items 18-27, wherein,

[0074] Step 6) The acid leaching treatment is to use a hydrochloric acid solution with a concentration of 0.1-2 mol / L to leach the first crude cristobalite sand of step 5), preferably at a stirring speed of 200-500 r / min, and the stirring leaching time is more than 1 hour;

[0075] Further preferably, the volume mass ratio of the added amount of the hydrochloric acid solution to the first crude cristobalite sand is 3-6 L / Kg.

[0076] 29. The method of any one of items 18-28, wherein,

[0077] After the acid leaching treatment of the first crude high-purity cristobalite sand obtained in step 5), the product of the acid leaching reaction is filtered, washed with ultrapure water until the pH of the washing liquid is 7, dried by baking, and refined high-purity cristobalite sand is obtained.

[0078] 30. A high-purity cristobalite sand, wherein the average particle size of the high-purity cristobalite sand is greater than 0.15 mm, the SiO2 content is 99%-99.9%, and the Ba content is less than 10 mg per kg of cristobalite sand, and the high-purity cristobalite sand is preferably prepared by the method of any one of items 18-29.

[0079] 31. A high-purity cristobalite sand prepared by the method of any one of items 18-29.

[0080] Inventive Effects

[0081] The raw material of the present application is derived from waste quartz crucibles, and the crystallization layer of the waste quartz crucibles is stripped by high-temperature treatment, which reduces the cost of manual work and also removes the organic impurities attached to the surface.

[0082] In the present application, the waste quartz crucibles are recycled by high-temperature treatment to prepare high-purity fused quartz glass sand and high-purity cristobalite sand with different particle sizes, which can be prepared without using quartz ore, greatly saving the waste of resources and achieving effective recycling of waste materials.

[0083] The SiO2 purity of the high-purity fused quartz glass sand produced by the present application can reach 98%. The SiO2 purity of the high-purity cristobalite sand produced by the present application can reach 98% or more. BRIEF DESCRIPTION OF DRAWINGS

[0084] Figure 1 Pictures showing waste quartz crucibles are shown;

[0085] Figure 2 Pictures A and B show the waste quartz crucibles at a baking temperature of 200℃;

[0086] Figure 3 Pictures A and B show the waste quartz crucibles at a baking temperature of 300℃;

[0087] Figure 4 A and B show pictures of waste quartz crucible at calcination temperature 400°C;

[0088] Figure 5 A and B show pictures of waste quartz crucible at calcination temperature 450°C;

[0089] Figure 6 XRD patterns of waste quartz crucible of Example 9 before and after crystallization treatment are shown;

[0090] Figure 7 XRD patterns of waste quartz crucible of Example 10 before and after crystallization treatment are shown;

[0091] Figure 8 XRD patterns of waste quartz crucible of Example 11 before and after crystallization treatment are shown;

[0092] Figure 9 XRD patterns of waste quartz crucible of Example 12 before and after crystallization treatment are shown;

[0093] Figure 10 XRD patterns of waste quartz crucible of Comparative Example 5 before and after crystallization treatment are shown;

[0094] Figure 11 XRD patterns of waste quartz crucible of Comparative Example 6 before and after crystallization treatment are shown. DETAILED DESCRIPTION

[0095] The following embodiments of the present application are merely used to illustrate the specific embodiments of realizing the present application, and these embodiments cannot be understood as the limitation of the present application. Any other changes, modifications, substitutions, combinations, simplifications, which are made without departing from the spirit and principle of the present application, are regarded as the equivalent replacement mode, and fall within the protection scope of the present application.

[0096] The specific embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present application can be more thoroughly understood and the scope of the present application can be fully conveyed to those skilled in the art.

[0097] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It is further understood that the use of certain terminology or words within the specification in no way limits the scope of the application to the specific terminology or words but rather is to be interpreted in the context of the specification as a whole.

[0098] As used herein, "substantially free of," with respect to a particular component, is used to denote that the particular component has not been deliberately formulated into the composition and / or is present only as a contaminant or in trace amounts. Thus, the total amount of a particular component resulting from any inadvertent contamination of the composition is less than 0.05%, preferably less than 0.01%. Most preferably, compositions are contemplated wherein the amount of a particular component is not detectable by standard analytical methods.

[0099] As used in this specification, "a" or "an" can mean one or more. As used in the claims, the word "a" or "an" when used in the context of a list of elements or steps can mean one or more than one.

[0100] The term "or" is used in the claims to mean "and / or" unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and "and / or." As used herein, "another" can mean at least a second or more.

[0101] The application provides a method for preparing high-purity cristobalite sand from waste quartz crucible, wherein the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) subjecting the first oversize obtained in step 1) to high-temperature calcination treatment to obtain a mixture material in which a surface crystallization layer containing cristobalite sand is separated from fused quartz glass sand; 3) subjecting the mixture material obtained in step 2) to self-milling and second screening, removing the second oversize, and taking the second undersize to obtain first cristobalite sand; 4) scrubbing the first cristobalite sand obtained in step 3), removing the third oversize by wet screening, and taking the third undersize to obtain high-purity cristobalite sand after processing. The method of the application can effectively utilize waste quartz crucibles and prepare high-purity cristobalite sand from waste quartz crucibles.

[0102] The application provides a method for preparing high-purity fused quartz glass sand by using waste quartz crucible, wherein the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) performing high-temperature calcination treatment on the first oversize obtained in step 1) to obtain a mixture material in which a surface crystallization layer containing cristobalite sand is separated from fused quartz glass sand; 3) performing self-milling and second screening on the mixture material obtained in step 2), removing the second undersize, and taking the second oversize to obtain first fused quartz glass sand; 4) performing scrubbing on the first fused quartz glass sand in step 3), and removing the fourth undersize by wet screening, and taking the fourth oversize to obtain high-purity fused quartz glass sand after treatment. The method can effectively utilize the waste quartz crucible, and the high-purity fused quartz glass sand prepared by using the waste quartz crucible meets the needs of different industries, and the crystallization layer can be recycled and utilized.

[0103] The application provides a method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand by using waste quartz crucible, wherein the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) performing high-temperature calcination treatment on the first oversize obtained in step 1) to obtain a mixture material in which a surface crystallization layer containing cristobalite sand is separated from fused quartz glass sand; 3) performing self-milling and second screening on the mixture material obtained in step 2), taking the second undersize to obtain first cristobalite sand, and taking the second oversize to obtain first fused quartz glass sand; 4) performing scrubbing on the crude first cristobalite sand in step 3), and removing the third oversize by wet screening, and taking the third undersize to obtain high-purity cristobalite sand after treatment, and performing scrubbing on the first fused quartz glass sand in step 3), and removing the fourth undersize by wet screening, and taking the fourth oversize to obtain high-purity fused quartz glass sand after treatment. The method can comprehensively utilize the waste quartz crucible, and the high-purity fused quartz glass sand and the high-purity fused quartz glass sand containing cristobalite produced by the method can both have a SiO2 purity of 98%, and the utilization rate of the waste crucible can be more than 95%.

[0104] In the application, the high-purity cristobalite sand refers to high-purity non-metal raw materials of a certain particle size specification having a cristobalite crystal phase, and specifically refers to high-quality quartz raw materials with a silicon dioxide content of 95.0% or preferably 96.0% or preferably 97.0% or preferably 98.0% or more.

[0105] In the application, the high-purity fused quartz glass sand refers to high-quality non-crystalline glass with a silicon oxide (for example, quartz, silica stone) content of 95.0% or preferably 96.0% or preferably 97.0% or preferably 98.0% or more, which has long-range disorder in atomic structure and provides high service temperature and low thermal expansion coefficient through three-dimensional structure cross-linking.

[0106] In the present application, particle size refers to the size of the aperture of the screen through which the particle can pass during the screening process. For example, a particle having a particle size greater than 0.83 mm is one that cannot pass through a screen having a diameter of 0.83 mm and is retained as oversize, while a particle having a particle size less than 0.83 mm can pass through the screen. In the present application, average particle size is a parameter used to characterize the entire powder body. It is generally considered that the undersize obtained by screening with a screen having a diameter of 0.83 mm has an average particle size less than 0.83 mm, while the oversize has an average particle size greater than 0.83 mm.

[0107] In the present application, the waste quartz crucible can be derived from any process, such as a waste quartz crucible that is broken due to crystallization, cracking and other stresses during the production of crystalline silicon products using the Czochralski method.

[0108] In the present application, crushing can be any crushing method that can be conceived by those skilled in the art, and is not limited to machine crushing or manual crushing. Machine crushing can be performed in any commercially available or self-made mechanical crusher, such as a hammer crusher, a jaw crusher, a roll crusher or a cone crusher. For example, a hammer crusher or a roll crusher can be used to crush the waste quartz crucible to a particle size of less than 10 mm. During the crushing process, the particle material can be crushed to quartz sand having a particle size of about 0.83 mm by crushing, and the particles having a particle size less than this can be collected, because the main force during crushing is extrusion shear, and the crusher has a fixed discharge size, and the fused quartz layer will satisfy a normal distribution. Thus, the particle size distribution range of the target material is mainly concentrated between 0.83 mm.

[0109] In the present application, screening is the collection of the fine powder of the crystallization layer stripped and crushed during the crushing process using a screen having a certain diameter. The shape of the aperture is not limited, as long as it meets its function, such as a square, circular, triangular and polygonal shape, or a cylindrical aperture, a conical aperture, a shaped aperture, a spline aperture and other special-shaped apertures. In some preferred embodiments of the present application, a square or circular aperture screen having a diameter of 0.83 mm or a square or circular aperture screen having a diameter of 0.15-0.18 mm is used.

[0110] In some embodiments, the first screening is performed using a sieve with a diameter of 0.7-0.9 mm, preferably 0.80-0.85 mm, and more preferably 0.83 mm. The sieve can be a square hole sieve or a round hole sieve. For example, the first screening can be performed using a sieve with a diameter of 0.7 mm, 0.71 mm, 0.72 mm, 0.73 mm, 0.74 mm, 0.75 mm, 0.76 mm, 0.76 mm, 0.78 mm, 0.79 mm, 0.80 mm, 0.81 mm, 0.82 mm, 0.83 mm, 0.84 mm, 0.85 mm, 0.86 mm, 0.86 mm, 0.88 mm, 0.89 mm, 0.90 mm, or any range therebetween.

[0111] In some embodiments, the roasting process is performed by placing the obtained waste quartz crucible particles in a high-temperature roasting furnace. The roasting process of step 2) is performed at a temperature of 300-500°C, preferably for 1 minute or more, preferably for 1 minute to 1 hour, and more preferably for 1 minute to 20 minutes. For example, the roasting process can be performed at a temperature of 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, or any range therebetween; and for a time period of 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or any range therebetween.

[0112] In this application, the temperature range for high-temperature roasting is because this temperature can meet the minimum temperature condition for the detachment of the cristobalite layer. Due to the difference in two types of phases, hardness, and volume expansion, high-temperature roasting can be used to separate the two substances, which are then separated by screening. Excessive detachment temperature will increase unnecessary energy consumption.

[0113] In some embodiments, step 2) of the method further comprises water cooling the first sieve residue after roasting, and recovering the cooled and dried material as the mixture. The cooling water is preferably used for the self-grinding after impurity removal by precipitation. The hot air is recovered for preheating of the particle material, and the hot water is used for wet self-grinding after impurity removal by precipitation.

[0114] In some embodiments, the self-milling in step 3) is selected from dry self-milling or wet self-milling, preferably the self-milling is carried out at a rotation speed of 300-500 r / min without adding grinding balls, further preferably the self-milling time is more than 1 minute, further preferably the self-milling is carried out for 1-30 minutes, further preferably the self-milling is carried out for 1-20 minutes. For example, the rotation speed of the self-milling can be 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min, 350 r / min, 360 r / min, 370 r / min, 380 r / min, 390 r / min, 400 r / min, 410 r / min, 420 r / min, 430 r / min, 440 r / min, 450 r / min, 460 r / min, 470 r / min, 480 r / min, 490 r / min, 500 r / min, or any range therebetween; the self-milling time can be 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, or any range therebetween.

[0115] In the present application, the self-milling can be dry or wet self-milling. The self-milling without adding grinding balls reduces the introduction of impurities due to wear of the grinding balls, and the grinding balls are spherical, which generates a grinding force under high-speed rotation, and is not conducive to the dissociation of high-hardness materials. The sample itself has different shapes, and the collision of the different shapes under high-speed motion makes the material preferentially break from the stress concentration area. The stress point of the material is concentrated on the bubble, and the material breaks along the bubble edge, which can achieve better grinding effect. At the same time, the target material in the present application is cristobalite crystallization layer and fused quartz, which have a large difference in hardness and brittleness. The self-milling process can make the high-hardness fused quartz form a selective grinding effect on the low-hardness cristobalite crystallization layer, and preferentially grind the cristobalite crystallization layer to a finer particle size, which is convenient for subsequent processing.

[0116] In the present application, the dry self-milling adopts a stirring tank, the rotation speed is 300-500 r / min, and the self-milling time is 1-15 min. The purpose of selecting this range of dry self-milling is to achieve the effect of selective grinding, and to avoid a too long grinding time to reduce the yield of the fused quartz on the screen.

[0117] In the present application, the wet autogenous grinding adopts a stirring tank, the rotation speed is 300-500 r / min, the autogenous grinding time is 10-30 min, and tap water is used for autogenous grinding. The purpose of using tap water for autogenous grinding and selecting the range is to meet the effect of selective grinding and avoid reducing the yield of the on-screen fused quartz due to too long grinding time.

[0118] In some specific manners, the second screening is performed by using a screen mesh with a diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm, and the screen mesh is preferably a square hole screen or a round hole screen; for example, the diameter can be 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm or any range therebetween.

[0119] In the present application, the scrubbing is any scrubbing manner known to those skilled in the art as long as the purpose is achieved. The scrubbing manner can be ultrasonic scrubbing, mechanical scrubbing or other scrubbing manners. Those skilled in the art can select the parameters of the scrubbing according to the actual situation as long as the purpose is achieved.

[0120] In some specific manners, the scrubbing in step 4) is performed by ultrasonic scrubbing on the first square quartz sand or the first fused quartz glass sand obtained in step 3), preferably the ultrasonic frequency is 10-40 kHz, further preferably the ultrasonic temperature is 20-80°C, and further preferably the ultrasonic time is 10-20 min; for example, the ultrasonic frequency can be 10 kHz, 11 kHz, 12 kHz, 13 kHz, 14 kHz, 15 kHz, 16 kHz, 17 kHz, 18 kHz, 19 kHz, 20 kHz, 21 kHz, 22 kHz, 23 kHz, 24 kHz, 25 kHz, 26 kHz, 27 kHz, 28 kHz, 29 kHz, 30 kHz, 31 kHz, 32 kHz, 33 kHz, 34 kHz, 35 kHz, 36 kHz, 37 kHz, 38 kHz, 39 kHz, 40 kHz or any range therebetween; the ultrasonic temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or any range therebetween; and the ultrasonic time can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min or any range therebetween.

[0121] In the present application, the frequency and temperature of the ultrasonic in step 4) are selected according to relevant experiments and considering better implementation in industry. The scrubbing has a preliminary purification effect and can remove impurities introduced in the attrition process or impurities carried by the material itself. The ultrasonic can remove suspended impurities and dust therein. The simultaneous scrubbing and ultrasonic cleaning can achieve better removal effect. The purpose of using glacial acetic acid is to reduce environmental pollution by using an organic weak acid, and glacial acetic acid also has a certain impurity removal effect on iron, calcium, barium and the like.

[0122] In some specific modes, the amount of the scrubbing liquid added for scrubbing is 5-10 times the mass of the first quartz sand or the first fused quartz glass sand, for example, can be 5 times, 6 times, 7 times, 8 times, 9 times, 10 times or any range therebetween.

[0123] In the present application, the acid medium used in the scrubbing liquid is not limited and can be a weak acid, for example, can be glacial acetic acid, oxalic acid, ascorbic acid, citric acid, hydrogen sulfide, hydrogen cyanide, hydrofluoric acid, phosphoric acid, boric acid, formic acid or other weak acids.

[0124] In some specific modes, the scrubbing liquid for scrubbing the first quartz sand includes, in mass parts, 1-20 parts of glacial acetic acid and 100-200 parts of water; for example, the glacial acetic acid can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts or any range therebetween; the water can be 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, 200 parts or any range therebetween; or the scrubbing liquid for scrubbing the first fused quartz glass sand includes, in mass parts, 1-20 parts of oxalic acid and 100-200 parts of water; for example, the oxalic acid can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts or any range therebetween; the water can be 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, 200 parts or any range therebetween.

[0125] The selection of the scrubbing liquid meets the scrubbing conditions, at the same time, makes the cost more economical and avoids the waste of excessive glacial acetic acid which is difficult to dissolve, and the amount of glacial acetic acid can be changed according to the amount of the material and the impurity content.

[0126] In some specific embodiments, the wet screening in step 4) is to screen the scrubbed material using a screen with a diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm, for example, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm or any range therebetween; preferably, the screen is a square hole screen or a round hole screen.

[0127] In some specific embodiments, the treatment of the third undersize or the fourth oversize after wet screening is to wash with ultrapure water until the pH of the rinse solution is 7; and to obtain high-purity quartz sand or high-purity fused quartz glass sand by drying.

[0128] The application provides a high-purity quartz sand, wherein the average particle size of the high-purity quartz sand is less than 0.18 mm, the SiO2 content is 98%-99.9%, and the Ba content is less than 15 mg per kg of quartz sand, and the high-purity quartz sand is preferably prepared by the method for preparing high-purity quartz sand from waste quartz crucibles mentioned in the application.

[0129] The application provides a high-purity quartz sand, which is prepared by the method for preparing high-purity quartz sand from waste quartz crucibles mentioned in the application.

[0130] The application provides a high-purity fused quartz glass sand, wherein the particle size of the high-purity fused quartz glass sand is 0.18-0.83 mm, the SiO2 content is 98%-99.9%, and the Ba content is less than 15 mg per kg of fused quartz glass sand, and the high-purity fused quartz glass sand is preferably prepared by the method for preparing high-purity fused quartz glass sand from waste quartz crucibles mentioned in the application.

[0131] The application provides a high-purity fused quartz glass sand, which is prepared by the method for preparing high-purity fused quartz glass sand from waste quartz crucibles mentioned in the application.

[0132] The application provides a method for preparing high-purity cristobalite sand from waste quartz crucible, wherein the method comprises the following steps: 1) crushing and fifthly screening the waste quartz crucible, removing the fifthly screened undersize, and taking the fifthly screened oversize; 2) subjecting the fifthly screened oversize obtained in step 1) to high-temperature calcination treatment to obtain a mixture of a surface crystallization layer containing cristobalite sand and fused quartz glass sand; 3) subjecting the mixture obtained in step 2) to self-milling and sixthly screening, removing the sixthly screened undersize, and taking the sixthly screened oversize to obtain first crude fused quartz glass sand; 4) subjecting the first crude fused quartz glass sand to rubbing and drying to obtain second crude fused quartz glass sand; 5) subjecting the second crude fused quartz glass sand obtained in step 4) to high-temperature crystal phase conversion to obtain the first crude cristobalite sand; and 6) obtaining high-purity cristobalite sand after subjecting the first crude cristobalite sand obtained in step 5) to acid immersion treatment.

[0133] Steps 1) to 4) can refer to the previous description, except that: the first screening is performed by using a screen with a diameter of 0.1-0.3 mm, preferably 0.15-0.25 mm, and further preferably a square-hole screen or a round-hole screen; the second screening is performed by using a screen with a diameter of 0.1-0.3 mm, preferably 0.15-0.25 mm, and further preferably 0.18 mm, and preferably a square-hole screen or a round-hole screen; and the rubbing liquid for rubbing the first crude fused quartz glass sand comprises, by mass fraction, 1-20 parts of oxalic acid and 100-200 parts of water.

[0134] The first screening is performed by using a screen with a diameter of 0.18 mm, and the quartz sand with a particle size of 0.18-10 mm is broken, and the particles below the particle size range are directly screened and discarded, because the main force in the crushing process is extrusion shear, and the crusher has a fixed discharge port size, and the fused quartz layer meets the normal distribution, so that the particle size distribution range of the target material is mainly concentrated in 0.25-10 mm. In this process, the broken product below the particle size range is mainly the cristobalite crystallization layer, which is different from the target material in the embodiment, so the undersize product is discarded, and the crushing to the particle size range is observed by an optical microscope, which can effectively remove most of the large-size bubbles in the fused quartz layer.

[0135] The rubbing liquid considers the purpose of oxalic acid, which is to reduce environmental pollution by using an organic weak acid, and the other purpose is that oxalic acid also has a dissolving effect on the main alkali metal impurities in the waste quartz crucible, such as aluminum, iron, calcium, etc., which can play a certain effect of removing impurities.

[0136] In some embodiments, the high temperature crystalline phase transformation of step 5) is performed using a high temperature calcination furnace at a temperature of 1470 °C to 1700 °C, preferably for a time period of 1 hour or more, and further preferably for a time period of 1 to 20 hours. For example, the high temperature calcination temperature can be 1470 °C, 1480 °C, 1490 °C, 1500 °C, 1510 °C, 1520 °C, 1530 °C, 1540 °C, 1550 °C, 1560 °C, 1570 °C, 1580 °C, 1590 °C, 1600 °C, 1610 °C, 1620 °C, 1630 °C, 1640 °C, 1650 °C, 1660 °C, 1670 °C, 1680 °C, 1690 °C, 1700 °C, or any range therebetween; and the calcination time period can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, or any range therebetween.

[0137] The high temperature transformation process, on one hand, can cause the bubbles to break, exposing the impurities in the bubbles, and the migration of other metal impurities from the inside to the outside, so that they are enriched on the surface or expelled, which is beneficial for subsequent removal. On the other hand, at high temperatures, the crystallization of the quartz crucible can be promoted, including the nucleation and crystal growth stages. The nucleation is caused by the promotion of crystallization by alkali metals or other impurities. At the same time, there is a certain similarity between the medium-range order structure of amorphous SiO2 and the dynamic disorder structure of cristobalite, which is more pronounced at high temperatures, thereby promoting the phase change behavior of SiO2 from amorphous to cristobalite. This temperature range is chosen because the quartz mineral transforms to cristobalite at a transformation point of 1470 °C. Below this range, the crystalline phase transformation is not achieved, and above this range, the quartz melts, which is not conducive to crystallization and also consumes too much unnecessary energy. Within this range, the crystalline phase transformation rate of the waste quartz crucible can reach 95% or more with different holding times.

[0138] In some specific embodiments, the acid leaching treatment of step 6) is acid leaching the first crude cristobalite sand of step 5) using a hydrochloric acid solution with a concentration of 0.1-2 mol / L, preferably under stirring at a stirring speed of 200-500 r / min for 1 hour or more; for example, the concentration of the hydrochloric acid solution can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, or any range therebetween; further preferably, the volume-to-mass ratio of the amount of the hydrochloric acid solution added to the first crude cristobalite sand is 3-6 L / Kg, for example, 3 L / Kg, 4 L / Kg, 5 L / Kg, 6 L / Kg, or any range therebetween. In the acid leaching treatment, an acid-resistant reaction kettle is used as the reaction container.

[0139] In some specific embodiments, after the acid leaching treatment of the first crude high-purity cristobalite sand obtained in step 5), the product of the acid leaching reaction is filtered and washed with ultrapure water until the pH of the washing liquid is 7; and the refined high-purity cristobalite is obtained by drying.

[0140] The present application provides a high-purity cristobalite sand, wherein the average particle size of the high-purity cristobalite sand is greater than 0.15 mm, the SiO2 content is 99%-99.9%, and the Ba content is less than 10 mg per kg of cristobalite sand, and the high-purity cristobalite sand is preferably prepared by the method for preparing high-purity cristobalite sand from waste quartz crucibles described above.

[0141] The present application provides a high-purity cristobalite sand, which is prepared by the method for preparing high-purity cristobalite sand from waste quartz crucibles described above.

[0142] In the present application, the materials or products obtained in each step can be detected by X-ray powder diffraction (XRD) to determine the category and crystal form of the materials or products; and the purity of the products obtained in the present application can be determined by the ICP-OES method.

[0143] In one specific embodiment of the present application, a method for preparing high-purity cristobalite sand from a separated crystallization layer of a waste quartz crucible, the method comprising the following steps: the waste quartz crucible is a quartz crucible that is discarded due to crystallization, cracking, and stress damage, and the SiO2 purity of the waste quartz crucible is above 97%; the crystallization layer is mainly cristobalite phase, and the other is amorphous phase fused quartz.

[0144] S1: the waste quartz crucible is placed in a mechanical crusher, and the waste quartz crucible is crushed to less than 0.83 mm.

[0145] Optionally, the mechanical crusher can be a hammer crusher, a jaw crusher, a cone crusher, etc.

[0146] S2: the waste quartz crucible is placed in a high-temperature roasting furnace, and the crystallization layer is completely separated from the fused quartz, the temperature is set to 300-500°C, and the holding time is 1-20 min.

[0147] Optionally, the high-temperature roasting furnace can be replaced by other high-temperature furnaces, high-temperature kilns, etc. The temperature is set to 300-500°C, for example, 300, 350, 400, 450°C, and the holding time is 1-20 min, for example, 1, 5, 10, 15, 20 min.

[0148] S3: the waste quartz crucible is self-ground, which can be dry self-ground or wet self-ground. Dry self-ground is to place the waste quartz crucible sand in a stirring tank, use centrifugal force to drive the low-hardness crystallization layer tridymite to rub against the high-hardness fused quartz, and then screen to obtain 0.18 mm coarse high-purity tridymite sand. The stirring tank is set to rotate at 300-500 r / min, and the self-grinding time is 1-20 min.

[0149] Optionally, the stirring tank can be replaced by other devices with stirring and self-rotation functions, and the self-grinding time is 1-20 min, for example, 1, 5, 10, 15, 20 min.

[0150] Wet self-grinding is to place the waste quartz crucible in a stirring tank, add a centrifugal force to further rub the low-hardness crystallization layer tridymite against the high-hardness fused quartz, and then obtain 0.18 mm refined high-purity tridymite sand. The rotation speed is set to 600 r / min, and the self-grinding time is 10-30 min.

[0151] Optionally, the stirring tank can be replaced by other devices with stirring and self-rotation functions, and the self-grinding time is 10-30 min, for example, 10, 15, 20, 30 min.

[0152] S4: the waste quartz crucible is ultrasonically scrubbed, and the scrubbing liquid used is 5-10 parts of glacial acetic acid and 100-200 parts of water. The waste quartz crucible is soaked in the scrubbing liquid and placed in an ultrasonic cleaner, which can loosen the interface between the crystallization layer and the fused quartz. The ultrasonic frequency is 10-40 KHZ, the ultrasonic temperature is 20-80°C, the ultrasonic time is 10-20 min, and after the scrubbing is finished, the crystallization layer fine powder ground and cleaned during the scrubbing and cleaning process is collected through a 0.18 mm square hole or round hole screen.

[0153] Optionally, the glacial acetic acid in the scrubbing liquid can be replaced by a weak organic acid such as oxalic acid or ascorbic acid. The ultrasonic scrubbing can also be replaced by mechanical scrubbing. The scrubbing time can be 10-20 min, for example, 10, 15, or 20 min; the ultrasonic frequency can be 10-40 kHz, and the temperature can be 20-80°C, for example, 20, 40, or 80°C.

[0154] S5: The refined high-purity quartz sand that has been scrubbed is rinsed until the rinsing liquid is neutral, and then the rinsed high-purity quartz sand is obtained as a finished product after being dried by hot air. The finished high-purity quartz sand has an average particle size of 0.1-0.15 mm, a SiO2content of 99%-99.9%, and a Ba content of less than 15 mg / kg.

[0155] In the present application, the detection of the proportion of crystalline phase in the quartz sand and the fused quartz glass sand is performed by using an X-ray diffractometer. Those skilled in the art can perform the detection based on the instruction manual of the instrument.

[0156] In the present application, the detection of the proportion of amorphous phase in the quartz sand and the fused quartz glass sand is performed by using an X-ray diffractometer. Those skilled in the art can perform the detection based on the instruction manual of the instrument.

[0157] In the present application, the content of each element in the quartz sand and the fused quartz glass sand is detected by using the ICP-OES method. Of course, other methods known to those skilled in the art can also be used.

[0158] The method of the present application can recycle waste quartz crucibles at a very low cost. Preliminary calculations show that the energy consumption cost per day of operation can be controlled within 150 yuan. The method can effectively achieve the transformation of waste into treasure, and produce high-purity fused quartz glass sand and high-purity quartz sand with a SiO2purity of more than 98%. The problem of needing to use quartz ore to prepare high-purity fused quartz glass sand and high-purity quartz sand is solved. In addition, it is unexpectedly found in the present application that controlling the calcination temperature within a reasonable range can separate the crystallization layer of the waste quartz crucible from the fused quartz, thereby making it possible to quickly and fully recover the waste quartz crucible.

[0159] Examples

[0160] The materials used in the tests and the test methods are generally and / or specifically described in the present application. In the following examples, % means wt%, i.e., weight percent, unless otherwise specified. The reagents or instruments used are not specified by the manufacturer, and are all conventional reagent products that can be obtained commercially.

[0161] High-temperature calcination experiment

[0162] In the high-temperature calcination experiment, the waste quartz crucible, for example,Figure 1 As shown in the design of high-temperature roasting temperature, many experiments were tried. Specifically as follows: the selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main component of the crystallization layer is cristobalite phase. First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to less than 10 mm, and then it is further crushed by a roll crusher, and the screen oversize stripped and crushed during the crushing process that does not pass through a square hole or round hole screen with a diameter of 0.83 mm is collected to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm. The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 200°C, the roasting time is 20 min, and after roasting, it is quickly taken out and poured into cooling water for cooling. Figure 2 As shown in the design of high-temperature roasting temperature, many experiments were tried. Specifically as follows: the selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main component of the crystallization layer is cristobalite phase. First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to less than 10 mm, and then it is further crushed by a roll crusher, and the screen oversize stripped and crushed during the crushing process that does not pass through a square hole or round hole screen with a diameter of 0.83 mm is collected to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm. The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 200°C, the roasting time is 20 min, and after roasting, it is quickly taken out and poured into cooling water for cooling. Figure 2 A represents working in a high-temperature furnace to 200°C, holding for 20 min, Figure 2 B represents holding for 20 min at 200°C, and the crystallization layer of the waste quartz crucible is not separated from the fused quartz.

[0163] Similarly, the applicant found that when the high-temperature roasting is 300°C, the crystallization layer and the fused quartz are not finally separated, as shown in Figure 3 As shown in the design of high-temperature roasting temperature, many experiments were tried. Specifically as follows: the selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main component of the crystallization layer is cristobalite phase. First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to less than 10 mm, and then it is further crushed by a roll crusher, and the screen oversize stripped and crushed during the crushing process that does not pass through a square hole or round hole screen with a diameter of 0.83 mm is collected to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm. The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 200°C, the roasting time is 20 min, and after roasting, it is quickly taken out and poured into cooling water for cooling. Figure 3 A represents working in a high-temperature furnace to 300°C, holding for 20 min, Figure 3 B represents holding for 20 min at 300°C, and the crystallization layer of the waste quartz crucible is not separated from the fused quartz.

[0164] Similarly, the applicant found that when the high-temperature roasting is 400°C, the crystallization layer and the fused quartz can be finally separated, as shown in Figure 4 As shown in the design of high-temperature roasting temperature, many experiments were tried. Specifically as follows: the selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main component of the crystallization layer is cristobalite phase. First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to less than 10 mm, and then it is further crushed by a roll crusher, and the screen oversize stripped and crushed during the crushing process that does not pass through a square hole or round hole screen with a diameter of 0.83 mm is collected to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm. The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 200°C, the roasting time is 20 min, and after roasting, it is quickly taken out and poured into cooling water for cooling. Figure 4 A represents working in a high-temperature furnace to 400°C, holding for 10 min, Figure 4 B represents holding for 10 min at 400°C, and the crystallization layer of the waste quartz crucible is separated from the fused quartz.

[0165] Similarly, the applicant found that when the high-temperature roasting is 450°C, the crystallization layer and the fused quartz can be finally separated, as shown in Figure 5 As shown in the design of high-temperature roasting temperature, many experiments were tried. Specifically as follows: the selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main component of the crystallization layer is cristobalite phase. First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to less than 10 mm, and then it is further crushed by a roll crusher, and the screen oversize stripped and crushed during the crushing process that does not pass through a square hole or round hole screen with a diameter of 0.83 mm is collected to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm. The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 200°C, the roasting time is 20 min, and after roasting, it is quickly taken out and poured into cooling water for cooling. Figure 5 A represents working in a high-temperature furnace to 450°C, holding for 5 min, Figure 5 B represents holding for 5 min at 450°C, and the crystallization layer of the waste quartz crucible is separated from the fused quartz.

[0166] Example 1 A method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible, the method comprising the following steps:

[0167] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main phase of the crystallization layer is cristobalite. The main impurity element content detected by ICP-OES method is shown in Table 1.

[0168] Table 1 Impurity element content (ppm) of waste quartz crucible

[0169] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 58.97 48.3 3.13 27.71 9.5 0.34 12.54 20.1 98.13 Fused quartz 47.46 41.1 2.14 25.79 8.54 0.5 17.49 13.04 98.81

[0170] In Table 1 and the following Tables 2-42, the units of elements other than SiO2 are ppm.

[0171] First, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to 10 mm, then passed through a roller crusher, and further crushed, and the screen oversize stripped off during the crushing process is collected through a square hole or round hole screen with a diameter of 0.83 mm, to obtain waste quartz crucible crystallization layer fine powder with a particle size greater than 0.83 mm.

[0172] The waste quartz crucible crystallization layer fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 300°C, the roasting time is 20 min, and after roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0173] The waste quartz crucible crystallization layer fine powder subjected to high-temperature roasting is dry ground, 1000g of waste quartz crucible cristobalite sand is placed in a stirring tank, the rotation speed is set to 300r / min, the self-milling time is 5min, and after the self-milling time is over, the crystallization layer fine powder stripped and ground during the heating roasting and self-milling is enriched by passing through a square hole or round hole screen with a diameter of 0.18mm;

[0174] First part:

[0175] The undersize of the diameter less than 0.18mm after self-milling is 550g of crude high-purity cristobalite sand (i.e. the first cristobalite sand).

[0176] The crude high-purity cristobalite sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of oxalic acid and 2000ml of water are added, the addition amount of the scrubbing solution is 5 times the mass of the crude high-purity cristobalite sand, the temperature is set to 60°C, the scrubbing time is 10min, the ultrasonic power is 10Khz, and after ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground during the heating roasting and self-milling is enriched by passing through a square hole or round hole screen with a diameter of 0.18mm, and the undersize is 500g of refined high-purity cristobalite sand.

[0177] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and then the high-purity quartz sand is obtained after hot air drying, and the SiO2 content of the high-purity quartz sand is 98.71%, and the Ba content is 9.51 mg / kg;

[0178] The second part: taking the oversize material with a diameter greater than 0.18 mm after self-grinding, that is, the crude fused quartz glass sand (i.e., the first fused quartz glass sand) 450 g.

[0179] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing liquid is configured, 200 g of oxalic acid and 2000 ml of water are added, the addition amount of the scrubbing liquid is 5 times the mass of the crude fused quartz glass sand, the temperature is set to 60°C, the scrubbing time is 10 min, the ultrasonic power is 10Khz, and after ultrasonic cleaning, the crystallization layer fine powder stripped and ground during the heating and calcination and self-grinding process is enriched by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the oversize material is taken, that is, the refined fused quartz glass sand 447 g.

[0180] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and then the high-purity fused quartz glass sand is obtained after hot air drying, and the SiO2 content of the high-purity fused quartz glass sand is 98.91%, and the Ba content is 11.11 mg / kg;

[0181] The impurity content detected by the ICP-OES method can be seen in Table 2.

[0182] Table 2 Impurity element content (ppm) of high-purity quartz sand and high-purity fused quartz glass sand

[0183]

[0184] Example 2 A method for preparing high-purity quartz sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible

[0185] The method comprises the following steps:

[0186] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the crystallization layer is mainly quartz phase. The main impurity element content detected by the ICP-OES method is shown in Table 3.

[0187] Table 3 Impurity element content (ppm) of waste quartz crucible

[0188] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 43.2 38.13 4.23 30.01 6.37 1.91 13.94 19.71 98.43 Fused quartz 36.7 30.11 2.13 27.71 5.01 1 9.95 10.2 98.87

[0189] Firstly, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roller crusher, and the exfoliated layer fine powder stripped in the crushing process is enriched by a square hole or circular hole screen with a diameter of 0.83 mm, the oversize is taken, and the waste quartz crucible sand with a particle size greater than 0.83 mm is obtained.

[0190] The exfoliated layer fine powder of the waste quartz crucible is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 320 DEG C, the roasting time is 15 min, after the roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0191] The exfoliated layer fine powder of the waste quartz crucible after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotating speed is set to 300r / min, the self-grinding time is 10 min, after the self-grinding time is over, the exfoliated layer fine powder stripped and ground in the heating and roasting and self-grinding processes is enriched by a square hole or circular hole screen with a diameter of 0.18 mm;

[0192] First part:

[0193] The undersize after self-grinding with a diameter less than 0.18 mm is 545g of crude high-purity quartz sand (i.e. first quartz sand).

[0194] The crude high-purity quartz sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of citric acid and 2000ml of water are added, the addition amount of the scrubbing solution is 5 times the mass of the crude high-purity quartz sand, the temperature is set to 65 DEG C, the scrubbing time is 12 min, the ultrasonic power is 10Khz, after the ultrasonic cleaning is completed, the exfoliated layer fine powder stripped and ground in the heating and roasting and self-grinding processes is enriched by a square hole or circular hole screen with a diameter of 0.18 mm, and the undersize is 543g of refined high-purity quartz sand.

[0195] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing solution shows neutral, then it is hot air dried to obtain 540g of finished high-purity quartz sand, the SiO2 content of the finished high-purity quartz sand is 98.78%, and the Ba content is 9.13mg / kg.

[0196] Second part:

[0197] The oversize after self-grinding with a diameter greater than 0.18 mm is 455g of crude fused quartz glass sand (i.e. first fused quartz glass sand).

[0198] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200 g of citric acid and 2000 ml of water are added, the amount of the scrubbing solution added is 5 times the mass of the crude fused quartz glass sand, the temperature is set to 65°C, the scrubbing time is 12 min, the ultrasonic power is 10 Khz, after the ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground during the heating roasting and self-grinding is enriched by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the sieve residue is taken, i.e. refined fused quartz glass sand 452 g.

[0199] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing solution shows neutrality, and then the product high-purity fused quartz glass sand 450 g is obtained after hot air drying. The SiO2 content of the product high-purity fused quartz glass sand is 99.15%, and the Ba content is 12.52 mg / kg.

[0200] The impurity contents detected by the ICP-OES method can be seen in Table 4.

[0201] Table 4 Impurity element contents (ppm) of high-purity cristobalite sand and high-purity fused quartz glass sand

[0202]

[0203] Example 3 A method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible

[0204] The method comprises the following steps:

[0205] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer mainly composed of cristobalite phase. The main impurity element contents detected by the ICP-OES method are shown in Table 5.

[0206] Table 5 Impurity element contents (ppm) of a waste quartz crucible

[0207] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 47.3 37.13 2.2 23.91 6 0.99 14.88 17.98 98.37 Fused quartz 36.7 32.32 2.4 19.41 4.99 0.99 11.01 11.41 98.79

[0208] First, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roll crusher, and the crystallization layer fine powder stripped and crushed during the crushing is enriched by passing through a square hole or circular hole sieve with a diameter of 0.83 mm, and the sieve residue is taken to obtain waste quartz crucible sand fine powder with a particle size greater than 0.83 mm,

[0209] The waste quartz crucible sand fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 400°C, the roasting time is 10 min, and after the roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0210] The high-temperature calcined waste quartz crucible sand fine powder is wet self-milled by adding 5000ml of water in a stirring tank, the rotating speed is set to 600r / min, and the self-milling time is 18min. After the self-milling time ends, the crystallization layer fine powder stripped and ground during the heating calcination and self-milling is enriched by passing through a square hole or circular hole sieve with a diameter of 0.18mm.

[0211] First part:

[0212] The undersize of the self-milled product with a diameter less than 0.18mm is the crude high-purity quartz sand (i.e. the first quartz sand) 570g. The quartz sand is transferred to an ultrasonic cleaning instrument.

[0213] The crude high-purity quartz sand is placed in the ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of glacial acetic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80℃, the scrubbing time is 15min, the ultrasonic power is 20Khz, after the ultrasonic cleaning ends, the crystallization layer fine powder stripped and ground during the heating calcination and self-milling is enriched by passing through a square hole or circular hole sieve with a diameter of 0.18mm, and the undersize is obtained, i.e. the refined high-purity quartz sand 567g.

[0214] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutrality, and then the high-purity quartz sand is obtained after hot air drying, i.e. the finished product high-purity quartz sand 565g, the SiO2 content of the finished product high-purity quartz sand is 99.61%, and the Ba content is 8.71mg / kg.

[0215] Second part:

[0216] The oversize of the self-milled product with a diameter greater than 0.18mm is the crude fused quartz glass sand (i.e. the first fused quartz glass sand) 430g.

[0217] The crude fused quartz glass sand is placed in the ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of glacial acetic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80℃, the scrubbing time is 15min, the ultrasonic power is 20Khz, after the ultrasonic cleaning ends, the crystallization layer fine powder stripped and ground during the heating calcination and self-milling is enriched by passing through a square hole or circular hole sieve with a diameter of 0.18mm, and the oversize is obtained, i.e. the refined fused quartz glass sand 425g.

[0218] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutrality, and then the high-purity fused quartz glass sand is obtained after hot air drying, i.e. the finished product high-purity fused quartz glass sand 418g, the SiO2 content of the finished product high-purity fused quartz glass sand is 99.81%, and the Ba content is 11.71mg / kg.

[0219] The impurity content detected by the ICP-OES method is shown in Table 6.

[0220] Table 6 Impurity element content (ppm) of high-purity cristobalite sand and high-purity fused quartz glass sand

[0221]

[0222] Example 4 Method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand from a separated crystallization layer of a waste quartz crucible

[0223] The method comprises the following steps:

[0224] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, which is mainly cristobalite phase. The main impurity element content detected by the ICP-OES method is shown in Table 7.

[0225] Table 7 Impurity element content (ppm) of waste quartz crucible

[0226] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 47 32.1 2.12 20.92 5.1 1.02 14.1 16.99 98.66 Fused quartz 35.41 29.74 2 17.41 4.78 0.87 9.01 10 98.81

[0227] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm. Then, the waste quartz crucible is further crushed by a roller crusher, and the crystallization layer fine powder stripped during the crushing process is enriched by passing through a square hole or circular hole screen with a diameter of 0.83 mm. The oversize material is taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.83 mm is obtained.

[0228] The waste quartz crucible sand fine powder is placed in a high-temperature calcination kiln for calcination. The calcination temperature is 500°C, and the calcination time is 3 min. After calcination, the waste quartz crucible sand fine powder is quickly taken out and cooled in cooling water.

[0229] The waste quartz crucible sand fine powder calcined at high temperature is dry ground. 1000 g of waste quartz crucible cristobalite sand is placed in a stirring tank, the rotation speed is set to 300 r / min, and the self-grinding time is 20 min. After the self-grinding time ends, the crystallization layer fine powder stripped and ground during the heating and calcination and self-grinding processes is enriched by passing through a square hole or circular hole screen with a diameter of 0.18 mm.

[0230] First part:

[0231] The undersize material with a diameter less than 0.18 mm after self-grinding is taken, i.e., 570 g of crude high-purity cristobalite sand (i.e., the first cristobalite sand).

[0232] The crude high-purity cristobalite sand is wet ground. 5000 ml of water is added in the stirring tank, the rotation speed is set to 500 r / min, and the self-grinding time is 20 min. After the self-grinding time ends, the cristobalite sand is transferred to an ultrasonic cleaning instrument.

[0233] The waste quartz crucible is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200 g of glacial acetic acid and 2000 ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80°C, the scrubbing time is 20 min, the ultrasonic power is 30Khz, after the ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground during heating, baking and self-grinding is removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the undersize material is taken, that is, refined high-purity quartz sand 574 g.

[0234] The refined high-purity quartz sand is washed with ultrapure water until the pH of the washing liquid shows neutral, and then the high-purity quartz sand is obtained after hot air drying, and the SiO2 content of the high-purity quartz sand is 99.96%, and the Ba content is 8.13 mg / kg.

[0235] Second part:

[0236] The oversize material with a diameter greater than 0.18 mm after self-grinding is taken, that is, crude fused quartz glass sand (i.e., first fused quartz glass sand) 420 g.

[0237] The crude fused quartz glass sand is wet self-ground, 5000 ml of water is added in the stirring tank, the rotation speed is set to 500 r / min, and the self-grinding time is 20 min. After the self-grinding time is completed, the crude fused quartz glass sand is transferred to the ultrasonic cleaning instrument.

[0238] A scrubbing solution is configured, 200 g of glacial acetic acid and 2000 ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80°C, the scrubbing time is 20 min, the ultrasonic power is 30Khz, after the ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground during heating, baking and self-grinding is removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the oversize material is taken, that is, refined fused quartz glass sand 415 g.

[0239] The refined fused quartz glass sand is washed with ultrapure water until the pH of the washing liquid shows neutral, and then the high-purity fused quartz glass sand is obtained after hot air drying, and the SiO2 content of the high-purity fused quartz glass sand is 99.98%, and the Ba content is 8 mg / kg.

[0240] The impurity content detected by the ICP-OES method can be seen in Table 8.

[0241] Table 8 Impurity element content (ppm) of high-purity quartz sand and high-purity fused quartz glass sand

[0242]

[0243] Embodiment 5 A method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand from a waste quartz crucible separation crystallization layer,

[0244] The method comprises the following steps:

[0245] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, which is mainly cristobalite phase. The main impurity element content detected by ICP-OES method is shown in Table 9.

[0246] Table 9 Impurity element content (ppm) of waste quartz crucible

[0247] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 58.2 47.3 3 28 8.95 0.3 9.9 18.1 99.39 Fused quartz 44.7 42.4 1 25.8 8.65 0.5 17.69 11.1 99.85

[0248] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm. Then, it is further crushed by a roll crusher, and the crystallization layer fine powder stripped off during the crushing process is removed through a square hole or circular hole sieve with a diameter of 0.83 mm. The sieve upper material is taken to obtain waste quartz crucible sand fine powder with a particle size greater than 0.83 mm.

[0249] The waste quartz crucible sand fine powder is placed in a high-temperature roasting furnace for roasting, and the roasting temperature is 300°C, and the roasting time is 20 min. After roasting, it is quickly taken out and cooled in cooling water.

[0250] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground. 1000g of waste quartz crucible quartz glass sand is placed in a stirring tank, the rotating speed is set to 200r / min, the self-grinding time is 5 min, and after the self-grinding time is over, the crystallization layer fine powder stripped and ground off during the heating and roasting and self-grinding processes is removed through a square hole or circular hole sieve with a diameter of 0.18 mm.

[0251] First part:

[0252] The sieve upper material with a diameter greater than 0.18 mm after self-grinding is taken, that is, 950g of crude fused quartz glass sand (i.e., the first fused quartz glass sand).

[0253] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of citric acid and 2000ml of water are added, the addition amount of the scrubbing solution is 5 times the mass of the crude fused quartz glass sand, the temperature is set to 60°C, the scrubbing time is 15 min, the ultrasonic power is 10Khz, and after the ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground off during the heating and roasting and self-grinding processes is removed through a square hole or circular hole sieve with a diameter of 0.18 mm. The sieve upper material is taken, that is, 930g of refined fused quartz glass sand,

[0254] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and the product high-purity fused quartz glass sand 925g is obtained after hot air drying. The SiO2 content of the product high-purity fused quartz glass sand is 99.91%, and the Ba content is 9.5mg / kg.

[0255] Second part:

[0256] The undersize of the diameter less than 0.18mm after self-milling is the crude high-purity cristobalite sand (i.e. the first cristobalite sand) 50g.

[0257] The crude high-purity cristobalite sand is placed in an ultrasonic cleaning instrument, and a scrubbing liquid is configured. 200g of citric acid and 2000ml of water are added. The addition amount of the scrubbing liquid is 5 times the mass of the crude high-purity cristobalite sand. The temperature is set to 60℃, the scrubbing time is 15min, and the ultrasonic power is 10Khz. After ultrasonic cleaning, the crystallization layer fine powder stripped and ground during the heating and calcination and self-milling process is removed by passing through a square hole or circular hole sieve with a diameter of 0.18mm. The undersize is taken, i.e. the refined high-purity cristobalite sand 48g,

[0258] The refined high-purity cristobalite sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and the product high-purity cristobalite sand 46g is obtained after hot air drying. The SiO2 content of the product high-purity cristobalite sand is 99.83%, and the Ba content is 14.78mg / kg.

[0259] The impurity content detected by the ICP-OES method can be seen in Table 10.

[0260] Table 10 Impurity element content (ppm) of high-purity cristobalite sand and high-purity fused quartz glass sand

[0261] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 35.10 27.5 0.53 20.30 6.45 0.49 13.33 9.50 99.91 Fused quartz 36.98 30.56 1.19 24.61 7.98 0.77 14.92 12.10 99.83

[0262] Example 6 A method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible, which method comprises the following steps:

[0263] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, which is mainly cristobalite phase. The main impurity element content detected by the ICP-OES method is shown in Table 11.

[0264] Table 11 Impurity element content (ppm) of waste quartz crucible

[0265] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) High-purity fused quartz glass sand 52.20 46.13 2.71 28.13 8.55 0.60 10.97 17.45 99.16 High-purity cristobalite sand 46.70 39.92 1.71 23.78 8.77 0.53 16.95 11.20 99.85

[0266] Firstly, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roller crusher, and the exfoliated layer fine powder stripped off during the crushing process is removed by a square hole or circular hole sieve with a diameter of 0.83 mm, the sieve upper material is taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.83 mm is obtained,

[0267] The waste quartz crucible sand fine powder is placed in a high-temperature roasting furnace for roasting, the roasting temperature is 300°C, the roasting time is 15 min, and after the roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0268] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz glass sand is placed in a stirring tank, the rotating speed is set to 200r / min, the self-grinding time is 10 min, and after the self-grinding time is over, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding is removed by a square hole or circular hole sieve with a diameter of 0.18 mm;

[0269] First part:

[0270] The sieve upper material with a diameter greater than 0.18 mm after self-grinding is taken, that is, 975g of crude fused quartz glass sand (i.e. first fused quartz glass sand).

[0271] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of oxalic acid and 2000ml of water are added, the addition amount of the scrubbing solution is 5 times the mass of the crude fused quartz glass sand, the temperature is set to 70°C, the scrubbing time is 15 min, the ultrasonic power is 10Khz, after the ultrasonic cleaning is completed, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding is removed by a square hole or circular hole sieve with a diameter of 0.18 mm, and the sieve upper material is taken, that is, 955g of refined fused quartz glass sand.

[0272] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and then it is hot air dried to obtain 950g of finished high-purity fused quartz glass sand, the SiO2 content of the finished high-purity fused quartz glass sand is 99.93%, and the Ba content is 9.11mg / kg.

[0273] Second part:

[0274] The sieve lower material with a diameter less than 0.18 mm after self-grinding is taken, that is, 25g of crude high-purity quartz sand (i.e. first quartz sand).

[0275] The crude high-purity quartz sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200 g of oxalic acid and 2000 ml of water are added, the amount of the scrubbing solution added is 5 times the mass of the crude high-purity quartz sand, the temperature is set to 70°C, the scrubbing time is 15 min, the ultrasonic power is 10 Khz, after the ultrasonic cleaning is completed, the crystallization layer fine powder stripped and ground during the heating and roasting and self-grinding processes is removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the undersize material is taken, that is, refined high-purity quartz sand 23 g.

[0276] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing solution shows neutrality, and then the high-purity quartz sand is obtained after being dried by hot air, and the SiO2 content of the finished high-purity fused quartz glass sand is 99.74%, and the Ba content is 13.16 mg / kg.

[0277] The impurity content detected by the ICP-OES method can be seen in Table 12.

[0278] Table 12 Impurity element content (ppm) of high-purity quartz sand and high-purity fused quartz glass sand

[0279]

[0280] Embodiment 7 A method for preparing high-purity quartz sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible, which comprises the following steps:

[0281] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, which is mainly composed of quartz phase. The main impurity element content detected by the ICP-OES method is shown in Table 13.

[0282] Table 13 Impurity element content (ppm) of waste quartz crucible

[0283] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 48.2 45.77 3.13 27.91 7.77 1 11.37 18.45 99.17 Fused quartz 44.7 37.44 2.22 24.01 5.34 0.7 17.44 11.2 99.79

[0284] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roll crusher, and the crystallization layer fine powder stripped and crushed during the crushing process is removed by passing through a square hole or circular hole sieve with a diameter of 0.83 mm, and the oversize material is taken to obtain waste quartz crucible sand fine powder with a particle size greater than 0.83 mm,

[0285] The waste quartz crucible sand fine powder is placed in a high-temperature roasting furnace for roasting, the roasting temperature is 400°C, the roasting time is 10 min, and after the roasting is completed, it is quickly taken out and cooled in cold water.

[0286] The high-temperature calcined waste quartz crucible sand fine powder is wet self-ground, 1000g of waste quartz crucible quartz glass sand is put into a stirring tank, 2000ml of tap water is added, the rotating speed is set to 500r / min, the self-grinding time is 15min, after the self-grinding time ends, the crystallization layer fine powder stripped and ground in the heating calcination and self-grinding process is removed by using a square hole or circular hole sieve with a diameter of 0.18mm;

[0287] The first part:

[0288] The sieve residue with a diameter greater than 0.18mm after self-grinding is the crude fused quartz glass sand (i.e. the first fused quartz glass sand) 960g.

[0289] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of glacial acetic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80℃, the scrubbing time is 15min, the ultrasonic power is 20Khz, after the ultrasonic cleaning ends, the crystallization layer fine powder stripped and ground in the heating calcination and self-grinding process is removed by using a square hole or circular hole sieve with a diameter of 0.18mm, and the sieve residue is taken, i.e. the refined fused quartz glass sand 950g.

[0290] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and then the high-purity fused quartz glass sand 940g is obtained after hot air drying, the SiO2 content of the high-purity fused quartz glass sand is 99.94%, and the Ba content is 10.75mg / kg.

[0291] The second part:

[0292] The sieve residue with a diameter greater than 0.18mm after self-grinding is the crude high-purity quartz sand (i.e. the first quartz sand) 40g.

[0293] The crude high-purity quartz sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of glacial acetic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80℃, the scrubbing time is 15min, the ultrasonic power is 20Khz, after the ultrasonic cleaning ends, the crystallization layer fine powder stripped and ground in the heating calcination and self-grinding process is removed by using a square hole or circular hole sieve with a diameter of 0.18mm, and the sieve residue is taken, i.e. the refined high-purity quartz sand 39g.

[0294] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing liquid shows neutral, and then the high-purity quartz sand 37g is obtained after hot air drying, the SiO2 content of the high-purity quartz sand is 99.83%, and the Ba content is 9.61mg / kg.

[0295] The impurity content detected by the ICP-OES method is shown in Table 14.

[0296] Table 14 Impurity element content (ppm) of high-purity cristobalite sand and high-purity fused quartz glass sand

[0297] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 33.43 20.94 0.5 17.43 3.12 0.51 9.71 10.75 99.94 Fused quartz 29.11 19.51 0.15 18.1 5.41 0.77 10.71 9.61 99.83

[0298] Example 8 A method for preparing high-purity cristobalite sand and high-purity fused quartz glass sand by separating the crystallization layer of a waste quartz crucible, the method comprising the following steps:

[0299] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, which is mainly cristobalite phase. The main impurity element content detected by the ICP-OES method is shown in Table 15.

[0300] Table 15 Impurity element content (ppm) of waste quartz crucible

[0301] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) High-purity fused quartz glass sand 41.2 40.77 2.51 24.13 5.41 1 12.1 17.3 99.73 High-purity cristobalite sand 39.7 37.41 1.79 20.43 3.91 0.68 15.44 11.12 99.91

[0302] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm. Then, it is further crushed by a roll crusher, and the stripped and crushed crystallization layer fine powder in the crushing process is removed through a square hole or circular hole sieve with a diameter of 0.83 mm to obtain waste quartz crucible sand fine powder with a particle size greater than 0.83 mm.

[0303] The waste quartz crucible sand fine powder is placed in a high-temperature roasting furnace for roasting, the roasting temperature is 500°C, the roasting time is 5 min, and after roasting, it is quickly taken out and poured into cooling water for cooling.

[0304] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz glass sand is placed in a stirring tank, the rotation speed is set to 200r / min, the self-grinding time is 15 min, and after the self-grinding time is over, the stripped and ground crystallization layer fine powder in the heating and roasting and self-grinding processes is removed through a square hole or circular hole sieve with a diameter of 0.18 mm;

[0305] First part:

[0306] The sieve residue with a diameter greater than 0.18 mm after self-grinding is taken, which is 980g of crude fused quartz glass sand (i.e., the first fused quartz glass sand).

[0307] The crude fused quartz glass sand is wet ground, 5000ml of water is added in the stirring tank, the rotation speed is set to 500r / min, and the self-grinding time is 20 min. After the self-grinding time is over, the quartz glass sand is transferred to an ultrasonic cleaning instrument.

[0308] The scrubbing solution is configured by adding 200 g of oxalic acid and 2000 ml of water. The sample is immersed in the scrubbing solution. The temperature is set to 80°C, and the scrubbing time is 20 min. The ultrasonic power is 20 kHz. After the ultrasonic cleaning, the fine powder of the crystallization layer peeled off and ground during the heating, baking and self-grinding is removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm. The sieve residue is obtained, and the refined fused quartz glass sand is 970 g.

[0309] The refined fused quartz glass sand is rinsed with ultrapure water until the pH of the rinsing solution shows neutrality. The product high-purity fused quartz glass sand is obtained after hot air drying, and the product high-purity fused quartz glass sand is 965 g. The SiO2 content of the product high-purity fused quartz glass sand is 99.98%, and the Ba content is 6.73 mg / kg.

[0310] Part II:

[0311] The sieve underflow of the self-ground quartz sand with a diameter of less than 0.18 mm is obtained, and the crude high-purity quartz sand (i.e., the first quartz sand) is 21 g.

[0312] The crude high-purity quartz sand is wet self-ground by adding 5000 ml of water in the stirring tank, and the rotation speed is set to 500 r / min. The self-grinding time is 20 min. After the self-grinding time, the quartz sand is transferred to the ultrasonic cleaning instrument.

[0313] The scrubbing solution is configured by adding 200 g of oxalic acid and 2000 ml of water. The sample is immersed in the scrubbing solution. The temperature is set to 80°C, and the scrubbing time is 20 min. The ultrasonic power is 20 kHz. After the ultrasonic cleaning, the fine powder of the crystallization layer peeled off and ground during the heating, baking and self-grinding is removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm. The sieve underflow is obtained, and the refined high-purity quartz sand is 20 g.

[0314] The refined high-purity quartz sand is rinsed with ultrapure water until the pH of the rinsing solution shows neutrality. The product high-purity quartz sand is obtained after hot air drying, and the product high-purity quartz sand is 19 g. The SiO2 content of the product high-purity quartz sand is 99.96%, and the Ba content is 9.51 mg / kg.

[0315] The impurity content detected by the ICP-OES method can be seen in Table 16.

[0316] Table 16 Impurity element content (ppm) of high-purity quartz sand and high-purity fused quartz glass sand

[0317]

[0318] Example 9 is a method for preparing high-purity quartz sand by deep processing of waste quartz crucible fused quartz, which comprises the following steps:

[0319] The selected waste quartz crucible is mainly fused quartz, the content of SiO2 is 98.61%, and the outer wall has a crystallization layer, the main phase of which is cristobalite, and the porosity of the bubble is 10.12%. The content of the main impurity elements detected by ICP-OES method is shown in Table 17.

[0320] Table 17 Impurity element content (ppm) of waste quartz crucible

[0321] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 40.7 30.4 1 18.8 8.5 0.5 18.3 11.1 98.61

[0322] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roll crusher, and the fine powder of the crystallization layer stripped off during the crushing process is removed through a square hole or circular hole screen with a diameter of 0.18 mm, to obtain waste quartz crucible sand fine powder with a particle size greater than 0.18 mm,

[0323] The waste quartz crucible sand fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 300°C, the roasting time is 20 min, and after the roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0324] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotation speed is set to 400r / min, the self-grinding time is 5 min, and after the self-grinding time is over, the fine powder of the crystallization layer stripped and ground off during the heating and roasting and self-grinding processes is removed through a square hole or circular hole screen with a diameter of 0.15 mm, and the sieve upper material is taken, that is, 960g of crude fused quartz glass sand (i.e. the first crude fused quartz glass sand).

[0325] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing liquid is configured, 200g of oxalic acid and 2000ml of water are added, the scrubbing liquid is added to cover the sample, the temperature is set to 40°C, the scrubbing time is 15 min, and the ultrasonic power is 20Khz. After the ultrasonic cleaning is completed, the fine powder of the crystallization layer stripped and ground off during the heating and roasting and self-grinding processes is removed through a square hole or circular hole screen with a diameter of 0.18 mm, and the sieve upper material is taken, that is, 955g of crude fused quartz glass sand (i.e. the second crude fused quartz glass sand), the impurity element content of the fused quartz glass sand after ultrasonic scrubbing can be seen in Table 18 (detected by ICP-OES method), and oxalic acid can be used.

[0326] Table 18 Impurity element content (ppm) of crude high-purity fused quartz glass sand

[0327] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 39.6 30.1 1 15.13 7.5 0.5 17.54 10.9 98.63

[0328] The crude fused quartz glass sand is loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, heated to 1550°C, and kept for 6 hours. After natural cooling, the crude high-purity quartz sand (i.e., the first crude quartz sand) is obtained, and the crystallization effect can be seen Fused quartz , Ingredients The XRD patterns of the fused quartz before and after phase transformation at 1550°C are shown. Before transformation, the waste quartz crucible is mainly amorphous fused quartz. After 6 hours of heat preservation at 1550°C, the fused quartz is basically transformed into quartz crystal phase, but the background of the low-angle diffraction peak is slightly high, indicating that the sample still contains a small amount of amorphous SiO2. The crystalline phase of the fused quartz in the waste quartz crucible is basically transformed, but there is a part of amorphous phase background; the impurity elements slightly increase, indicating that the internal bubbles are opened and release the contained impurities. The porosity of the first crude quartz sand is 2.66%, and the impurity elements are shown in Table 19 (detected by ICP-OES method).

[0329] Table 19 Impurity element content (ppm) of the first crude quartz sand

[0330] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 6 47.1 32.5 1.19 19.3 10.5 2.5 19.65 11.9 98.61

[0331] The crude high-purity quartz sand is placed in an acid-resistant reaction kettle, and a 0.1 mol / L hydrochloric acid solution is added while stirring for acid leaching. The stirring speed is 300 r / min, and the stirring and acid leaching time is 3 hours. After acid leaching reaction, the reaction product is filtered, and the filter residue is washed with ultrapure water until the pH of the washing liquid is neutral. The filter residue is dried to obtain high-purity quartz sand.

[0332] Table 20 Impurity element content (ppm) of high-purity quartz sand

[0333] Figure 6 Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 30.1 17..5 0.53 15..3 6.45 0.47 15.33 9.57 99.1

[0334] The filter residue is dried to obtain 950g of high-purity quartz sand. The SiO2 content of the high-purity quartz sand is 99.10%, and the Ba content is 9.57mg / kg. Different particle sizes of high-purity quartz sand products can be obtained by grinding and grading.

[0335] Example 10 A method for preparing high-purity quartz sand by crystalline phase transformation of waste quartz crucible fused quartz, which comprises the following steps:

[0336] The selected waste quartz crucible is mainly fused quartz, with a SiO2 content of 98.73%, and a crystallization layer on the outer wall, mainly quartz phase, with a bubble porosity of 10.12%. The main impurity element content is shown in Table 21 (detected by ICP-OES method).

[0337] Table 21 Impurity element content (ppm) of waste quartz crucible

[0338] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 38.57 33.7 1.66 25.3 9.4 0.87 16.39 13.1 98.73

[0339] First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10 mm, then passed through a roller crusher, further crushed, and the exfoliated layer fine powder stripped off during the crushing process is removed through a square hole or round hole screen with a diameter of 0.18 mm, and the oversize is taken to obtain waste quartz crucible sand fine powder with a particle size greater than 0.18 mm,

[0340] The waste quartz crucible sand fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 350°C, the roasting time is 15 min, and after the roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0341] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotation speed is set to 400r / min, the self-grinding time is 10 min, and after the self-grinding time is over, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed through a square hole or round hole screen with a diameter of 0.15 mm, and the oversize is taken, which is 978g of crude fused quartz glass sand (i.e., the first crude fused quartz glass sand).

[0342] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 200g of oxalic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 60°C, the scrubbing time is 12 min, and the ultrasonic power is 20Khz, after the ultrasonic cleaning is completed, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed through a square hole or round hole screen with a diameter of 0.18 mm, and the oversize is taken, which is 975g of crude fused quartz glass sand (i.e., the second crude fused quartz glass sand) high-purity fused quartz glass sand. The sample after ultrasonic scrubbing can be seen in Table 22 (detected by ICP-OES method).

[0343] Table 22 Impurity element content (ppm) of crude high-purity fused quartz glass sand

[0344] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 36.14 31.23 1.54 20.3 7.73 0.71 16.29 13.1 98.76

[0345] The crude fused quartz glass sand is loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, heated to 1600°C, and held for 3h, then taken out after natural cooling to obtain crude high-purity cristobalite sand (i.e., the first crude cristobalite sand), and the crystallization effect can be seen Fused quartz , IngredientsXRD patterns of fused quartz before and after phase transformation at 1600°C are shown. Before transformation, the waste quartz crucible is mainly amorphous fused quartz. After holding at 1600°C for 3h, the transformation effect is basically the same as that after holding at 1550°C for 6h. The fused quartz is basically transformed into cristobalite crystal phase, but the background of the low-angle diffraction peak is slightly high, indicating that the sample still contains a small amount of amorphous SiO2. The impurity element content can be seen in Table 23 (determined by ICP-OES method). The crystal phase of the fused quartz of the waste quartz crucible is basically transformed, but there is a part of amorphous phase background. It is calculated that the porosity of the cristobalite is 2.12%.

[0346] Table 23 Impurity element content (ppm) of crude high-purity cristobalite sand

[0347] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 7 39.0 33.43 1.68 21.96 7.83 0.76 16.47 12.91 98.75

[0348] The crude high-purity cristobalite sand is placed in an acid-resistant reaction kettle, and a hydrochloric acid solution with a concentration of 0.5 mol / L is added while stirring. The stirring speed is 300 r / min, and the stirring and acid immersion time is 3h. After the acid immersion reaction, the reaction product is filtered, and the filter residue is washed with ultrapure water until the pH of the washing liquid is neutral. The filter residue is dried to obtain high-purity cristobalite sand, which can be seen in Table 24 (determined by ICP-OES method).

[0349] Table 24 Impurity element content (ppm) of waste quartz crucible

[0350] Figure 7 Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 31.51 24.47 1.56 13.3 6.64 0.31 11.7 9.1 99.53

[0351] The filter residue is dried to obtain 970g of high-purity cristobalite sand. The SiO2 content of the high-purity cristobalite sand is 99.53%, and the Ba content is 9.10mg / kg. Different particle sizes of high-purity cristobalite sand products can be obtained by grinding and grading.

[0352] Example 11 is a method for preparing high-purity cristobalite sand by phase transformation of fused quartz from waste quartz crucible, which comprises the following steps: the selected waste quartz crucible is mainly fused quartz, the SiO2 content is 98.88%, the outer wall has a crystallization layer, the main phase of the crystallization layer is cristobalite, and the bubble porosity is 10.12%. The main impurity element content is shown in Table 25 (determined by ICP-OES method).

[0353] Table 25 Impurity element content (ppm) of waste quartz crucible

[0354] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 39.14 30.79 2.1 20.31 11.01 2.11 17.15 10.9 98.88

[0355] First, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roll crusher, and the exfoliated layer fine powder stripped off during the crushing process is removed by a square hole or circular hole screen with a diameter of 0.18 mm, the oversize is taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.18 mm is obtained,

[0356] The waste quartz crucible sand fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 400°C, the roasting time is 10 min, and after roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0357] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000 g of waste quartz crucible quartz sand is placed in a stirring tank, the rotating speed is set to 400 r / min, the self-grinding time is 10 min, after the self-grinding time is over, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed by a square hole or circular hole screen with a diameter of 0.15 mm, and the oversize, i.e. 980 g of crude fused quartz glass sand (i.e. the first crude fused quartz glass sand) is taken.

[0358] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 400 g of oxalic acid and 2000 ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 70°C, the scrubbing time is 10 min, and the ultrasonic power is 20 Khz, after ultrasonic cleaning is completed, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed by a square hole or circular hole screen with a diameter of 0.18 mm, and the oversize, i.e. 985 g of crude fused quartz glass sand (i.e. the second crude fused quartz glass sand) is taken. The impurity elements of the crude fused quartz glass sand can be seen in Table 26 (determined by ICP-OES method).

[0359] Table 26 Impurity element content (ppm) of crude fused quartz glass sand

[0360] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 36.04 26.5 1.48 17.76 9.01 1.12 14.1 8.91 99.1

[0361] The crude fused quartz glass sand is loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, the temperature is raised to 1600°C, and the temperature is maintained for 4 h, after natural cooling, the crude high-purity cristobalite sand (i.e. the first crude cristobalite sand) is taken out, and the crystallization effect can be seen in Fused quartz , IngredientsXRD patterns of fused quartz before and after crystallization at 1600 °C are shown. Before crystallization, the waste quartz crucible is mainly amorphous fused quartz. After holding at 1600 °C for 4 h, the crystallization effect is better than that after holding at 1600 °C for 3 h. The fused quartz is basically converted into cristobalite crystal phase. The background of the low-angle diffraction peak is slightly high, indicating that the sample still contains a small amount of amorphous SiO2. The impurity element content can be seen in Table 27 (determined by ICP-OES method). The crystalline phase of the fused quartz of the waste quartz crucible is basically converted, but there is a part of amorphous phase background. It is calculated that the porosity of the cristobalite is 2.01%.

[0362] Table 27 Impurity element content (ppm) of crude high-purity cristobalite sand

[0363] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 8 37.83 27.13 1.73 19.76 10.81 1.31 14.9 9.35 98.96

[0364] The crude high-purity cristobalite sand is placed in an acid-resistant reaction kettle, and a hydrochloric acid solution with a concentration of 1 mol / L is added while stirring. The stirring speed is 300 r / min, and the stirring and acid immersion time is 2.5 h. After the acid immersion reaction, the reaction product is filtered, and the filter residue is washed with ultrapure water until the pH of the washing liquid is neutral. The filter residue is dried to obtain high-purity cristobalite sand. The impurity element content can be seen in Table 28 (determined by ICP-OES method).

[0365] Table 28 Impurity element content (ppm) of refined high-purity cristobalite sand

[0366] Figure 8 Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 25.37 17.13 1.01 10.1 5.49 0.64 6.89 9.02 99.81

[0367] The filter residue is dried to obtain 983 g of high-purity cristobalite sand. The SiO2 content of the high-purity cristobalite sand is 99.81%, and the Ba content is 9.02 mg / kg. Different particle sizes of high-purity cristobalite sand products can be obtained by grinding and grading.

[0368] Example 12 is a method for preparing high-purity cristobalite sand by crystallizing fused quartz from waste quartz crucible, which comprises the following steps: the selected waste quartz crucible is mainly fused quartz, the SiO2 content is 98.88%, and there is a crystallization layer on the outer wall, the main phase of the crystallization layer is cristobalite, and the bubble porosity is 10.12%. The main impurity element content is shown in Table 29 (determined by ICP-OES method).

[0369] Table 29 Impurity element content (ppm) of waste quartz crucible

[0370] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 40.51 28.31 1.93 19.77 10.31 1.08 15.15 11.1 98.83

[0371] First, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then it is further crushed by a roll crusher, and the exfoliated layer fine powder stripped off during the crushing process is removed by a square hole or circular hole screen with a diameter of 0.18 mm, the oversize is taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.18 mm is obtained,

[0372] The waste quartz crucible sand fine powder is placed in a high-temperature roasting kiln for roasting, the roasting temperature is 500°C, the roasting time is 5 min, and after roasting is completed, it is quickly taken out and poured into cooling water for cooling.

[0373] The waste quartz crucible sand fine powder after high-temperature roasting is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotating speed is set to 400r / min, the self-grinding time is 10 min, after the self-grinding time is over, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed by a square hole or circular hole screen with a diameter of 0.15 mm, and the oversize is taken, that is, 990g of crude fused quartz glass sand (i.e., the first crude fused quartz glass sand).

[0374] The crude fused quartz glass sand is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 400g of oxalic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80°C, the scrubbing time is 10 min, the ultrasonic power is 40Khz, after ultrasonic cleaning is completed, the exfoliated layer fine powder stripped and ground off during the heating roasting and self-grinding process is removed by a square hole or circular hole screen with a diameter of 0.18 mm, and the oversize is taken, that is, 985g of crude fused quartz glass sand (i.e., the second crude fused quartz glass sand). The impurity elements of the crude fused quartz glass sand can be seen in Table 30 (determined by ICP-OES method).

[0375] Table 30 Impurity element content (ppm) of crude fused quartz glass sand

[0376] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 32.04 24.5 0.99 14.96 6.96 1.31 12.99 9.93 98.97

[0377] The crude fused quartz glass sand is loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, the temperature is raised to 1650°C, and the temperature is maintained for 4h, and after natural cooling, the crude high-purity cristobalite sand (i.e., the first crude cristobalite sand) is taken out, and the crystallization effect can be seen in Fused quartz , IngredientsThe XRD patterns of fused silica before and after the phase transformation at 1650℃ are shown. Before the transformation, the waste quartz crucible mainly contained amorphous fused silica. After holding at 1650℃ for 4 hours, compared with the transformation effect after holding at 1600℃ for 4 hours, the crystallization effect was more prominent, and the fused silica was almost completely transformed into the cristobalite crystalline phase. The content of impurity elements can be seen in Table 31 (detected using the ICP-OES method). The fused silica in the waste quartz crucible underwent a basic phase transformation, but some amorphous phase remained on the back. The porosity of this high-purity cristobalite sand was calculated to be 1.98%.

[0378] Table 31 Impurity element content (ppm) of crude high-purity quartz sand

[0379] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 9 34.56 27.13 1.33 17.71 7.71 1.43 13.79 9.96 98.95

[0380] The crude high-purity cristobalite sand was placed in an acid-resistant reactor, and a 2 mol / L hydrochloric acid solution was added while stirring for acid leaching. The stirring speed was 300 r / min, and the acid leaching time was 1 h. After the acid leaching reaction, the reaction product was filtered, and the filter residue was washed with ultrapure water until the pH of the washing solution was neutral. The filter residue was dried to obtain high-purity cristobalite sand. The content of impurity elements is shown in Table 32 (determined by ICP-OES method).

[0381] Table 32 Impurity element content (ppm) of high-purity crisscross quartz sand

[0382] Figure 9 Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 23.17 12.23 0.51 8.33 4.19 0.29 4.14 8.15 99.95

[0383] The filter residue was dried to obtain 983g of high-purity cristobalite sand. The high-purity cristobalite sand had a SiO2 content of 99.95% and a Ba content of 8.51mg / kg. High-purity cristobalite sand products of different particle sizes can be obtained through grinding and classification.

[0384] Analysis reveals that the crystalline phase content of waste quartz crucibles increases with increasing temperature and holding time. Therefore, appropriately increasing the high-temperature temperature and extending the holding time is beneficial for increasing the crystalline phase content of molten quartz transformed from waste quartz crucibles. This application utilizes waste quartz crucibles to prepare cristobalite through crystalline phase transformation. This method not only enables the resource utilization of waste quartz crucibles, saves space, and protects the environment, but also offers simple operation, achieving a crystalline phase transformation rate of over 90% and a SiO2 content of over 99.9%.

[0385] Comparative Example 1's method includes the following steps:

[0386] The selected waste quartz crucibles were mainly composed of fused quartz with a crystallized layer on the outer wall. The crystallized layer was mainly composed of cristobalite phase, and the contents of the main impurity elements are shown in Table 33 (detected using the ICP-OES method).

[0387] Table 33 Impurity element content (ppm) of the waste quartz crucible

[0388] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 54.5 42.21 2.45 25.4 9.34 0.22 19.43 15.67 99.36 Fused quartz 41.34 45.65 1.73 24.04 5.61 0.36 17.67 17.95 99.55

[0389] First, the waste quartz crucible was placed in a jaw crusher, most of the waste quartz crucible was crushed to 15 mm, then passed through a roll crusher, further crushing was carried out, and the exfoliated layer fine powder stripped off during the crushing process was collected through a square hole or round hole screen with a diameter of 0.83 mm, the oversize was taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.83 mm was obtained.

[0390] The waste quartz crucible sand fine powder was placed in a high-temperature roasting furnace kiln for roasting, the roasting temperature was 200°C, the roasting time was 60 min, after the roasting was completed, it was quickly taken out and poured into cooling water for cooling.

[0391] The waste quartz crucible sand fine powder after high-temperature roasting was dry ground, 500g of waste quartz crucible quartz glass sand was placed in a stirring tank, the rotating speed was set to 200r / min, the self-grinding time was 5 min, after the self-grinding time was completed, the exfoliated layer fine powder stripped off and ground during the heating roasting and self-grinding process was collected through a square hole or round hole screen with a diameter of 0.18 mm, it was screened and analyzed, most of the glass sand was still contained on the screen, and complete separation of the exfoliated layer and fused quartz was not achieved.

[0392] The method of Comparative Example 2 includes the following steps:

[0393] The selected waste quartz crucible was mainly fused quartz, and the outer wall had an exfoliated layer, the main phase of the exfoliated layer was quartz, and the main impurity element content was as shown in Table 34 (detected by ICP-OES method).

[0394] Table 34 Impurity element content (ppm) of the waste quartz crucible

[0395] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 53.64 43.57 2.78 21.36 5.31 0.44 18.42 16.35 99.47 Fused quartz 42.37 36.59 1.67 23.75 5.96 0.37 16.77 19.67 99.51

[0396] First, the waste quartz crucible was placed in a jaw crusher, most of the waste quartz crucible was crushed to 10 mm, then passed through a roll crusher, further crushing was carried out, and the exfoliated layer fine powder stripped off during the crushing process was collected through a square hole or round hole screen with a diameter of 0.83 mm, the oversize was taken, and the waste quartz crucible sand fine powder with a particle size greater than 0.83 mm was obtained.

[0397] The waste quartz crucible sand fine powder was placed in a high-temperature roasting furnace kiln for roasting, the roasting temperature was 400°C, the roasting time was 10 min, after the roasting was completed, it was quickly taken out and poured into cooling water for cooling.

[0398] The high-temperature calcined waste quartz crucible sand fine powder was subjected to wet ball milling. 500 g of waste quartz crucible quartz sand was placed in a stirring tank, 100 g of agate balls was added, the rotation speed was set to 230 r / min, and the ball milling time was 15 min. After the ball milling time ended, the crystallization layer fine powder stripped and ground off during the heating calcination and self-milling process was removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and was collected. The collected crystallization layer fine powder was 347 g.

[0399] The screened crystallization layer fine powder failed to separate the crystallization layer from the fused quartz.

[0400] The method of Comparative Example 3 includes the following steps:

[0401] The selected waste quartz crucible was mainly fused quartz, and the outer wall had a crystallization layer, which was mainly composed of cristobalite phase. The main impurity element content is shown in Table 35 (determined by ICP-OES method).

[0402] Table 35 Impurity element content (ppm) of waste quartz crucible

[0403] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 54.5 42.21 2.45 25.4 9.34 0.22 19.43 15.67 99.36 Fused quartz 41.34 45.65 1.73 24.04 5.61 0.36 17.67 17.95 99.55

[0404] First, the waste quartz crucible was placed in a jaw crusher, and most of the waste quartz crucible was crushed to 15 mm. Then, the waste quartz crucible was further crushed by a roll crusher, and the crystallization layer fine powder stripped and crushed during the crushing process was removed by passing through a square hole or circular hole sieve with a diameter of 0.83 mm. The waste quartz crucible sand fine powder with a particle size greater than 0.83 mm was obtained,

[0405] The waste quartz crucible sand fine powder was placed in a high-temperature calcination furnace for calcination. The calcination temperature was 200°C, and the calcination time was 30 min. After calcination, the waste quartz crucible sand fine powder was quickly taken out and cooled in cold water.

[0406] The high-temperature calcined waste quartz crucible sand fine powder was subjected to dry self-milling. 500 g of waste quartz crucible quartz glass sand was placed in a stirring tank, the rotation speed was set to 200 r / min, and the self-milling time was 5 min. After the self-milling time ended, the crystallization layer fine powder stripped and ground off during the heating calcination and self-milling process was removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm. The sieve residue was 420 g of cristobalite-containing crude high-purity fused quartz glass sand.

[0407] The sieve still contained part of the cristobalite sand, and failed to separate the crystallization layer from the fused quartz.

[0408] The method of Comparative Example 4 includes the following steps:

[0409] The selected waste quartz crucible is mainly fused quartz, and the outer wall has a crystallization layer, and the main impurity element content of the crystallization layer is shown in Table 36 (determined by ICP-OES method).

[0410] Table 36 Impurity element content (ppm) of waste quartz crucible

[0411] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 53.64 43.57 2.78 21.36 5.31 0.44 18.42 16.35 99.47 Fused quartz 42.37 36.59 1.67 23.75 5.96 0.37 16.77 19.67 99.51

[0412] Firstly, the waste quartz crucible is placed in a jaw crusher, and most of the waste quartz crucible is crushed to 10 mm, and then passes through a roller crusher, and the crystallization layer fine powder stripped during crushing is removed through a square hole or round hole screen with a diameter of 0.83 mm, and the waste quartz crucible glass sand with a particle size greater than 0.83 mm is obtained,

[0413] The waste quartz crucible glass sand is placed in a high-temperature calcination furnace kiln for calcination, the calcination temperature is 400°C, the calcination time is 10 min, and after the calcination is completed, it is quickly taken out and poured into cooling water for cooling.

[0414] The waste quartz crucible glass sand is dry ball milled, 500g of waste quartz crucible quartz glass sand is placed in a stirring tank, 200g of agate ball is added, the rotating speed is set to 200r / min, the ball milling time is 15min, and after the ball milling time is over, the crystallization layer fine powder stripped and ground during heating and calcination and grinding is removed through a square hole or round hole screen with a diameter of 0.18mm, and the sieve material is 347g of crude high-purity fused quartz glass sand containing cristobalite.

[0415] The screen still contains part of the cristobalite sand, and the separation of the crystallization layer and the fused quartz is not achieved. The SiO2 purity of the crude high-purity fused quartz glass sand containing cristobalite is reduced to 98.94%.

[0416] The method of Comparative Example 5 includes the following steps:

[0417] The selected waste quartz crucible is mainly fused quartz, and the SiO2 content is 98.92%, and the outer wall has a crystallization layer, and the main impurity element content of the crystallization layer is shown in Table 37 (determined by ICP-OES method).

[0418] Table 37 Impurity element content (ppm) of waste quartz crucible

[0419] Ingredients Al Ca Cu Fe K Li Mg Ba SiO2(%) Crystallized layer 45.41 38.11 2.01 20.05 11.7 2.41 17.11 12.41 98.92

[0420] (1) First, the waste quartz crucible is placed in a hammer crusher, most of the waste quartz crucible is crushed to 10 mm, then passed through a roller crusher, further crushing, and the exfoliated layer fine powder stripped off during the crushing process is removed through a square hole or round hole screen with a diameter of 0.18 mm, obtaining waste quartz crucible sand fine powder with a particle size greater than 0.18 mm,

[0421] (2) The waste quartz crucible sand fine powder is placed in a high-temperature calcination kiln for calcination, the calcination temperature is 350°C, the calcination time is 10 min, after calcination, it is quickly taken out and poured into cooling water for cooling, and part of the crystallization layer is still attached to the glass sand.

[0422] (3) The waste quartz crucible sand fine powder after high-temperature calcination is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotation speed is set to 400r / min, the self-grinding time is 10 min, after the self-grinding time is over, the exfoliated layer fine powder stripped and ground off during the heating and calcination and self-grinding process is removed through a square hole or round hole screen with a diameter of 0.15 mm, and the sieve upper material is 990g of fused quartz glass sand.

[0423] The waste quartz crucible is placed in an ultrasonic cleaning instrument, a scrubbing solution is configured, 50g of oxalic acid and 2000ml of water are added, the scrubbing solution is added to cover the sample, the temperature is set to 80°C, the scrubbing time is 10 min, the ultrasonic power is 40Khz, after ultrasonic cleaning, the exfoliated layer fine powder stripped and ground off during the heating and calcination and self-grinding process is removed through a square hole or round hole screen with a diameter of 0.18 mm, and the sieve upper material is 985g of crude fused quartz glass sand (i.e. the first crude fused quartz glass sand). The impurity elements of the crude fused quartz glass sand can be seen in Table 38 (detected by ICP-OES method).

[0424] Table 38 Impurity element content (ppm) of crude fused quartz glass sand

[0425] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 40,01 35.41 1.71 18.31 9.31 2,41 16.68 11.72 98.97

[0426] The crude fused quartz glass sand is loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, heated to 1440°C, and kept for 1h, then taken out after natural cooling, obtaining crude high-purity quartz sand (i.e. the first crude quartz sand), and the crystallization effect can be seen in Fused quartz , IngredientsXRD patterns of fused quartz before and after phase transformation at 1440℃ are shown. Before transformation, the waste quartz crucible is mainly amorphous fused quartz. After 1h at 1440℃, the sample is basically amorphous, but a characteristic peak of cristobalite appears, and the crystallization effect is poor. The impurity element content can be seen in Table 39. The fused quartz of the waste quartz crucible has not been transformed completely, and is still amorphous background, and has not been able to precipitate internal impurities, and has not been able to break the bubbles.

[0427] Table 39 Impurity element content (ppm) of crude high-purity cristobalite sand

[0428] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 10 38.44 31.44 1.61 17.71 8.13 2.03 14.92 10.31 98.99

[0429] Comparative Example 6

[0430] In this comparative example, the method for preparing cristobalite from fused quartz of the waste quartz crucible described above failed to prepare high-purity cristobalite, and the method comprises the following steps:

[0431] The selected waste quartz crucible is mainly fused quartz, with a SiO2 content of 98.81%, and a crystallization layer on the outer wall, mainly cristobalite phase. The main impurity element content is shown in Table 40 (determined by ICP-OES method).

[0432] Table 40 Impurity element content (ppm) of waste quartz crucible

[0433] Figure 10 Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 50.41 43.35 3.61 29.71 12.99 3.12 19.12 13,11 98.81

[0434] (1) First, the waste quartz crucible is placed in a hammer crusher, and most of the waste quartz crucible is crushed to 10mm, then it is further crushed by a roll crusher, and the crystallization layer fine powder stripped off during the crushing process is removed by a square hole or circular hole screen with a diameter of 0.18mm, and the oversize material is taken to obtain a waste quartz crucible sand fine powder with a particle size greater than 0.18mm,

[0435] (2) The waste quartz crucible sand fine powder is placed in a high-temperature calcination kiln for calcination, the calcination temperature is 300℃, the calcination time is 30min, after calcination, it is quickly taken out and cooled in cooling water, and most of the crystallization layer is attached to the glass sand.

[0436] (3) The waste quartz crucible sand fine powder after high-temperature calcination is dry ground, 1000g of waste quartz crucible quartz sand is placed in a stirring tank, the rotation speed is set to 400r / min, the self-grinding time is 10min, after the self-grinding time is over, the crystallization layer fine powder stripped and ground off during the heating and calcination and self-grinding process is removed by a square hole or circular hole screen with a diameter of 0.15mm, and the oversize material is taken, which is 990g of crude fused quartz glass sand (i.e. the first crude fused quartz glass sand).

[0437] The crude fused quartz glass sand was placed in an ultrasonic cleaning instrument, and a scrubbing solution was configured, 100 g of oxalic acid and 2000 ml of water were added, the scrubbing solution was added to cover the sample, the temperature was set to 25°C, the scrubbing time was 10 min, and the ultrasonic power was 40Khz. After ultrasonic cleaning, the crystallization layer fine powder peeled off and ground off during the heating and calcining and self-grinding processes was removed by passing through a square hole or circular hole sieve with a diameter of 0.18 mm, and the sieve residue was taken, i.e. 985 g of crude fused quartz glass sand (i.e. the second crude fused quartz glass sand). The impurity elements of the crude fused quartz glass sand can be seen in Table 41 (detected by ICP-OES method).

[0438] Table 41 Impurity element content (ppm) of crude fused quartz glass sand

[0439] Fused quartz Al Ingredients Ca Cu K Fe Li Mg SiO2(%) Ba 47.12 39.11 3.12 25.01 1.43 3 17.41 12.87 98.87

[0440] The crude fused quartz glass sand was loaded into a gold melting crucible and placed in a high-temperature furnace for high-temperature conversion treatment, heated to 1300°C, and held for 8h. After natural cooling, the crude high-purity cristobalite sand (i.e. the first crude cristobalite sand) was obtained, and the crystallization effect can be seen in Fused quartz , Ingredients The XRD patterns of fused quartz before and after phase conversion at 1300°C are shown. Before conversion, the waste quartz crucible was mainly amorphous fused quartz. After holding at 1300°C for 8h, the sample was basically amorphous, but three characteristic peaks of cristobalite appeared, and the crystallization effect was poor. The impurity element content can be seen in Table 42. The fused quartz of the waste quartz crucible was not completely converted, and was still amorphous background, and was unable to precipitate internal impurities and break bubbles.

[0441] Table 42 Impurity element content (ppm) of crude high-purity cristobalite sand

[0442] Ca Al Cu Fe Li K Mg Ba Fused quartz SiO2(%) Figure 11 38.44 31.44 1.61 17.71 8.13 2.03 14.92 10.31 98.94

[0443] Table 43 List of main conditions of Examples 1-8 and Comparative Examples 1-4

[0444]

[0445]

[0446] Table 44 Examples 9-12 and Comparative Examples 5-6

[0447]

[0448] Cost calculation of experimental example purification process

[0449] The equipment used in the process of treating waste quartz crucible includes horizontal beneficiation fine grinding machine, ultrasonic cleaning machine / scouring machine, jaw crusher, ball mill, vibrating screen, plate and frame filter press, high temperature furnace and reaction kettle. The amount, processing capacity and power of the above equipment can refer to the parameters of the commonly used equipment in the market.

[0450] The reagent cost (referring to the information of commercially available drugs) is as follows:

[0451] According to the calculation of treating 1 ton of waste quartz crucible per day (the processing capacity of each step is different from the yield of the previous step, and the table 45 has been converted):

[0452] Table 45: Use of drugs and cost

[0453] Figure 11 Ingredients Ca Cu H2C2O4 5600 5 2.8 Fe 1400～1700 10 1.4～1.7 Li Mg Ba Fused quartz Medicines (industrial grade) Amount (yuan / ton) Amount (ton / week) Cost (ten thousand yuan) HCl Total 7000～7300 / 4.2～4.5

[0454] Note: Due to the difference in the purity of the selected drugs, there is a certain deviation between the amount and price of the drugs shown and the actual situation.

[0455] The energy consumption cost is as follows:

[0456] According to the above-mentioned reference of the power of each device, it is calculated that the energy consumption is about 115-145.2 kW per operation, and the energy consumption cost is about 117.875-148.83 yuan per day operation at the price of 1.025 yuan per kilowatt hour. It can be seen that the above-mentioned method of the present application can be used to estimate the recycling of waste quartz crucible in a very economical and energy-saving way.

[0457] Although the above describes the embodiments of the present application, the present application is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative and guiding, but not limiting. Those skilled in the art can make many forms under the guidance of the present application and without departing from the scope protected by the claims of the present application, which all belong to the protection of the present application.

Claims

1. A method for producing high purity cristobalite sand using waste quartz crucibles, wherein, The waste quartz crucible is a quartz crucible used in the production of crystal silicon products by using the pulling method; the main component of the waste quartz crucible is fused quartz, the inner and outer walls or the outer wall of the waste quartz crucible have a crystallization layer, and the main component of the crystallization layer is cristobalite phase; the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) high-temperature roasting the first oversize obtained in step 1) to obtain a mixed material in which the surface crystallization layer containing cristobalite sand is separated from the fused quartz glass sand; 3) self-milling and second screening the mixed material obtained in step 2), removing the second undersize, taking the second oversize to obtain first cristobalite sand, and taking the second oversize to obtain first fused quartz glass sand; 4) scrubbing the first cristobalite sand of step 3), removing the third oversize by wet screening, and taking the third undersize to obtain high-purity cristobalite sand after processing, and scrubbing the first fused quartz glass sand of step 3), removing the fourth undersize by wet screening, and taking the fourth oversize to obtain high-purity fused quartz glass sand after processing.

2. A method for producing high purity fused quartz glass sand using waste quartz crucibles, wherein, The waste quartz crucible is a quartz crucible used in the production of crystal silicon products by using the pulling method; the main component of the waste quartz crucible is fused quartz, the inner and outer walls or the outer wall of the waste quartz crucible have a crystallization layer, and the main component of the crystallization layer is cristobalite phase; the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) high-temperature roasting the first oversize obtained in step 1) to obtain a mixed material in which the surface crystallization layer containing cristobalite sand is separated from the fused quartz glass sand; 3) self-milling and second screening the mixed material obtained in step 2), removing the second undersize, taking the second oversize to obtain first cristobalite sand, and taking the second oversize to obtain first fused quartz glass sand; 4) scrubbing the first cristobalite sand of step 3), removing the third oversize by wet screening, and taking the third undersize to obtain high-purity cristobalite sand after processing, and scrubbing the first fused quartz glass sand of step 3), removing the fourth undersize by wet screening, and taking the fourth oversize to obtain high-purity fused quartz glass sand.

3. A method for producing high purity cristobalite sand and high purity fused quartz glass sand using waste quartz crucibles, wherein, The waste quartz crucible is a quartz crucible used in the production of crystal silicon products by using the pulling method; the main component of the waste quartz crucible is fused quartz, the inner and outer walls or the outer wall of the waste quartz crucible have a crystallization layer, and the main component of the crystallization layer is cristobalite phase; the method comprises the following steps: 1) crushing and first screening the waste quartz crucible, removing the first undersize, and taking the first oversize; 2) high-temperature roasting the first oversize obtained in step 1) to obtain a mixed material in which the surface crystallization layer containing cristobalite sand is separated from the fused quartz glass sand; 3) self-milling and second screening the mixed material obtained in step 2), taking the second undersize to obtain first cristobalite sand, and taking the second oversize to obtain first fused quartz glass sand; 4) scrubbing the first cristobalite sand of step 3) and removing the third oversize by wet screening, taking the third undersize to obtain high-purity cristobalite sand after processing, and scrubbing the first fused quartz glass sand of step 3) and removing the fourth undersize by wet screening, taking the fourth oversize to obtain high-purity fused quartz glass sand after processing.

4. The method of any one of claims 1-3, wherein, The waste quartz crucible is crushed to a particle size of less than 10 mm by crushing in step 1).

5. The method of claim 4, wherein, The crushing in step 1) is performed by using a hammer crusher or a roll crusher.

6. The method according to any one of claims 1-3, wherein, The first screening is performed by using a screen with a diameter of 0.7-0.9 mm.

7. The method of claim 6, wherein, The first screening is performed by using a screen with a diameter of 0.80-0.85 mm.

8. The method of claim 7, wherein, The first screening is performed by using a screen with a diameter of 0.83 mm.

9. The method of claim 6, wherein, The screen is a square hole screen or a round hole screen.

10. The method according to any one of claims 1-3, wherein, The roasting in step 2) is performed at a temperature of 300-500℃.

11. The method of claim 10, wherein, The roasting time is more than 1 minute.

12. The method of claim 11, wherein, The roasting time is 1 minute to 1 hour.

13. The method of claim 12, wherein, The roasting time is 1 minute to 20 minutes.

14. The method according to any one of claims 1-3, wherein, The step 2) of the method further comprises water cooling the first screening oversize after roasting, and recovering the first screening oversize after drying as the mixture; or The autogenous grinding in step 3) is selected from dry autogenous grinding or wet autogenous grinding.

15. The method of claim 14, wherein, The cooling water is used for the autogenous grinding after being removed of impurities by precipitation.

16. The method of claim 14, wherein, The autogenous grinding is performed without adding grinding balls at a rotation speed of 300-500 r / min.

17. The method of claim 14, wherein, The autogenous grinding time is more than 1 minute.

18. The method of claim 14, wherein, The autogenous grinding time is 1 minute to 30 minutes.

19. The method of claim 14, wherein, The autogenous grinding time is 1 minute to 20 minutes.

20. The method according to any one of claims 1-3, wherein, The second screening is performed by using a screen with a diameter of 0.1-0.2 mm.

21. The method of claim 20, wherein, The second screening is performed by using a screen with a diameter of 0.15-0.18 mm.

22. The method of claim 20, wherein, The screen is a square hole screen or a round hole screen.

23. The method according to any one of claims 1-3, wherein, The scrubbing in step 4) is performed by using ultrasonic on the first square quartz sand or the first fused quartz glass sand obtained in step 3).

24. The method of claim 23, wherein, The ultrasonic frequency is 10-40 kHz.

25. The method of claim 23, wherein, The ultrasonic temperature is 20-80℃.

26. The method of claim 23, wherein, The ultrasonic time is 10-20 min.

27. The method of claim 23, wherein, The amount of the scrubbing liquid used for the scrubbing is 5-10 times the mass of the first square quartz sand or the first fused quartz glass sand.

28. The method of claim 23, wherein, The scrubbing liquid used for the first square quartz sand comprises, by mass fraction, 1-20 parts of glacial acetic acid and 100-200 parts of water; or the scrubbing liquid used for the first fused quartz glass sand comprises, by mass fraction, 1-20 parts of oxalic acid and 100-200 parts of water.

29. The method according to any one of claims 1-3, wherein, The wet screening in step 4) is performed by using a screen with a diameter of 0.1-0.2 mm on the scrubbed material.

30. The method of claim 29, wherein, The wet screening is performed by using a screen with a diameter of 0.15-0.18 mm on the scrubbed material.

31. The method of claim 29, wherein, The screen is a square hole screen or a round hole screen.

32. The method according to any one of claims 1-3, wherein, The treatment of the third screening undersize or the fourth screening oversize after the wet screening is washing with ultrapure water until the pH of the washing liquid is 7, and drying to obtain high-purity square quartz sand or high-purity fused quartz glass sand.

33. A high purity cristobalite sand, wherein, The average particle size of the high-purity cristobalite sand is less than 0.18 mm, the SiO2 content is 98% to 99.9%, and the Ba content is less than 15 mg per kg of cristobalite sand, and the high-purity cristobalite sand is prepared by the method of claim 1 or 3.

34. A high purity fused silica glass sand, wherein, The average particle size of the high-purity fused quartz glass sand is 0.18 mm to 0.83 mm, the SiO2 content is 98% to 99.9%, and the Ba content is less than 15 mg per kg of fused quartz glass sand, and the high-purity fused quartz glass sand is prepared by the method of claim 2 or 3.

35. A method for producing high purity cristobalite sand from scrap quartz crucibles, wherein, The waste quartz crucible is a quartz crucible used in the production of crystalline silicon products by the Czochralski method; the main component of the waste quartz crucible is fused quartz, and the inner and outer walls or the outer wall of the waste quartz crucible have a crystallization layer, and the main component of the crystallization layer is cristobalite phase; the method comprises the following steps: 1) crushing and fifth screening the waste quartz crucible, removing the fifth undersize, and taking the fifth oversize; 2) high-temperature calcination treatment of the fifth oversize obtained in step 1) to obtain a mixture of the surface crystallization layer containing cristobalite sand and fused quartz glass sand separated; 3) self-milling and sixth screening of the mixture obtained in step 2), removing the sixth undersize, and taking the sixth oversize to obtain first crude fused quartz glass sand; 4) scrubbing and drying the first crude fused quartz glass sand to obtain second crude fused quartz glass sand; 5) high-temperature crystal phase conversion of the second crude fused quartz glass sand obtained in step 4) to obtain first crude cristobalite sand; 6) obtaining high-purity cristobalite sand after acid leaching treatment of the first crude cristobalite sand obtained in step 5).

36. The method of claim 35, wherein, The waste quartz crucible is crushed to a particle size of less than 10 mm by crushing in step 1).

37. The method of claim 36, wherein, The crushing in step 1) is carried out by using a hammer crusher or a roller crusher.

38. The method of any one of claims 35-37, wherein, The fifth screening is carried out by using a screen with a diameter of 0.1-0.3 mm.

39. The method of claim 38, wherein, The fifth screening is carried out by using a screen with a diameter of 0.15-0.25 mm.

40. The method of claim 38, wherein, The fifth screening is carried out by using a screen with a diameter of 0.18 mm.

41. The method of claim 38, wherein, The screen is a square hole screen or a round hole screen.

42. The method of any one of claims 35-37, wherein, The calcination treatment in step 2) is carried out at a temperature of 300-500°C.

43. The method of claim 42, wherein, The calcination time is more than 1 minute.

44. The method of claim 42, wherein, The calcination time is 1 minute to 1 hour.

45. The method of claim 42, wherein, The calcination time is 1 minute to 20 minutes.

46. The method of any one of claims 35-37, wherein, Step 2) further comprises water cooling the fifth oversize after calcination, and recovering the mixture after drying; or The self-milling in step 3) is selected from dry self-milling or wet self-milling.

47. The method of claim 46, wherein, The cooling water is used for self-milling after being precipitated and impurity-removed.

48. The method of claim 46, wherein, The self-milling is carried out without adding grinding balls at a rotation speed of 300-500 r / min.

49. The method of claim 46, wherein, The self-milling time is more than 1 minute.

50. The method of claim 46, wherein, The self-milling time is 1 minute to 30 minutes.

51. The method of claim 46, wherein, The self-milling time is 1 minute to 20 minutes.

52. The method of any one of claims 35-37, wherein, the sixth screening is performed using a screen with a diameter of 0.1-0.3 mm.

53. The method of claim 52, wherein, the sixth screening is performed using a screen with a diameter of 0.15-0.25 mm.

54. The method of claim 52, wherein, the sixth screening is performed using a screen with a diameter of 0.15 mm.

55. The method of claim 52, wherein, the screen is a square hole screen or a round hole screen.

56. The method of any one of claims 35-37, wherein, the scrubbing in step 4) is performed by ultrasonic scrubbing of the first crude fused quartz glass sand obtained in step 3).

57. The method of claim 56, wherein, the ultrasonic frequency is 10-40 kHz.

58. The method of claim 56, wherein, the ultrasonic temperature is 20-80 °C.

59. The method of claim 56, wherein, the ultrasonic time is 10-20 min.

60. The method of claim 56, wherein, the amount of scrubbing liquid added for the scrubbing is 5-10 times the mass of the first crude high-purity quartz sand or the first crude fused quartz glass sand.

61. The method of claim 60, wherein, the scrubbing liquid for the scrubbing of the first crude fused quartz glass sand comprises, by mass parts: 1-20 parts of oxalic acid, 100-200 parts of water.

62. The method of any one of claims 35-37, wherein, the high-temperature crystalline phase transformation in step 5) is performed using a high-temperature calcination furnace at a temperature of 1470 °C-1700 °C.

63. The method of claim 62, wherein, the calcination time is 1 hour or more.

64. The method of claim 62, wherein, the calcination time is 1-20 h.

65. The method of any one of claims 35-37, wherein, the acid leaching treatment in step 6) is performed using a hydrochloric acid solution with a concentration of 0.1-2 mol / L on the first crude quartz sand obtained in step 5).

66. The method of claim 65, wherein, the stirring speed is 200-500 r / min.

67. The method of claim 65, wherein, the stirring and acid leaching time is 1 hour or more.

68. The method of claim 65, wherein, the volume mass ratio of the hydrochloric acid solution to the first crude quartz sand is 3-6 L / Kg.

69. The method of any one of claims 35-37, wherein, after the acid leaching treatment of the first crude high-purity quartz sand obtained in step 5), the product of the acid leaching reaction is filtered and washed with ultrapure water until the pH of the washing liquid is 7; the refined high-purity quartz sand is obtained by drying.

70. A high purity cristobalite sand, wherein, the average particle size of the high-purity quartz sand is greater than 0.15 mm, the SiO2 content is 99%-99.9%, and the Ba content is less than 10 mg per kg of quartz sand, which is prepared by the method of any one of claims 35-69.

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