CN116969469A

CN116969469A - Recovery method of waste quartz crucible, prepared product and application thereof

Info

Publication number: CN116969469A
Application number: CN202310797093.4A
Authority: CN
Inventors: 彭云成; 代正发
Original assignee: Longi Green Energy Technology Co Ltd
Current assignee: Longi Green Energy Technology Co Ltd
Priority date: 2023-06-30
Filing date: 2023-06-30
Publication date: 2023-10-31

Abstract

The application relates to a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, wherein the method comprises the following steps of: 1) Crushing and first screening the waste quartz crucible, and respectively collecting first undersize matters and first oversize matters; 2) Performing high-temperature roasting treatment on the first oversize product obtained in the step 1) to obtain a mixed material of a surface crystallization layer containing cristobalite sand and fused silica glass sand; 3) Performing self-grinding and second screening on the mixed material obtained in the step 2), taking second undersize to obtain first quartz sand, and taking second oversize to obtain first fused quartz glass sand; 4) Scrubbing the quartz sand of the first party in the step 3), carrying out wet screening to collect third oversize products, and then processing the third oversize products to obtain first high-purity cristobalite sand, and collecting third undersize products, and then processing the third undersize products to obtain second high-purity cristobalite sand.

Description

Recovery method of waste quartz crucible, prepared product and application thereof

Technical Field

The application relates to the field of recycling of solid wastes, in particular to a recycling method utilizing a waste quartz crucible and particularly prepared high-purity cristobalite sand or high-purity fused quartz glass sand.

Background

The quartz crucible is made of SiO ₂ The quartz glass crucible produced by taking high-purity quartz sand with the content higher than 99.997% as a raw material is widely used for preparing crystalline silicon products, and is used as a key consumable in new energy and semiconductor industry, the inner wall and the outer wall of the high-purity quartz crucible can generate crystallization layers, and the crystallization layers can lead to the breakage of the quartz crucible. In the prior art, broken quartz crucibles are generally discarded, and are piled up or buried, so that the cost of piling up or burying is high, and huge pressure is brought to the environment and space. Therefore, there is an urgent need for a more environmentally friendly treatment method.

Disclosure of Invention

In order to solve the technical problems, the application aims to provide the following scheme:

1. a method for preparing cristobalite sand and fused silica glass sand using a waste quartz crucible, wherein the method comprises the steps of:

1) Crushing and first screening the waste quartz crucible, and respectively collecting first undersize matters and first oversize matters; acid washing the first undersize obtained in the step 1) to obtain first quartz sand;

2) Performing high-temperature roasting treatment on the first oversize product obtained in the step 1) to obtain a mixed material of a surface crystallization layer containing cristobalite sand and fused silica glass sand;

3) Performing self-grinding and second screening on the mixed material obtained in the step 2), taking second undersize to obtain first quartz sand, and taking second oversize to obtain first fused quartz glass sand;

4) Scrubbing the quartz sand of the first party in the step 3), carrying out wet screening to collect third oversize products, and then processing the third oversize products to obtain first high-purity cristobalite sand, and collecting third undersize products, and then processing the third undersize products to obtain second high-purity cristobalite sand.

2. A method for preparing cristobalite sand and fused silica glass sand using a waste quartz crucible, wherein the method comprises the steps of:

4) Scrubbing the first fused silica glass sand in the step 3), carrying out wet screening to collect fourth oversize products, and then processing to obtain first high-purity fused silica glass sand, and collecting fourth undersize products, and then processing to obtain second high-purity fused silica glass sand.

3. A method for preparing cristobalite sand and fused silica glass sand using a waste quartz crucible, wherein the method comprises the steps of:

4) Scrubbing the first quartz sand in the step 3), carrying out wet screening to collect third oversize materials, processing to obtain first high-purity cristobalite sand, collecting third undersize materials, processing to obtain second high-purity cristobalite sand, scrubbing the first fused silica glass sand in the step 3), carrying out wet screening to collect fourth oversize materials, processing to obtain first high-purity fused silica glass sand, and collecting fourth undersize materials, processing to obtain second high-purity fused silica glass sand.

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

the waste quartz crucible is a quartz crucible used in the production of crystalline silicon products by adopting a pulling method.

5. The method according to any one of claims 1 to 3, wherein the waste quartz crucible is crushed to particles having a particle size of less than 10mm by crushing in step 1);

the crushing in step 1) is preferably carried out using a hammer crusher or a twin roll crusher.

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

the first screening is carried out by adopting a screen with the diameter of 0.7-0.9 mm, preferably 0.80-0-85 mm, more preferably 0.83mm, and preferably the screen is a square hole screen or a round hole screen.

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

the baking treatment in step 2) is performed at a temperature of 300 to 500 ℃, preferably for a period of 1 minute or more, preferably for 1 minute to 1 hour, and more preferably for 1 minute to 20 minutes.

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

step 2) of the method further comprises water-cooling the calcined first undersize and recovering as the mixed material after drying, preferably by precipitating the cooling water for self-grinding after removing impurities.

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

the autogenous grinding in step 3) is selected from dry autogenous grinding or wet autogenous grinding, preferably autogenous grinding is carried out under the condition that grinding balls are not added and the rotating speed is 300-500 r/min, more preferably the autogenous grinding time is more than 1 minute, still more preferably the autogenous grinding is 1 minute to 30 minutes, still more preferably the autogenous grinding is 1 minute to 20 minutes.

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

the second screening is carried out by adopting a screen with the diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm, and the screen is preferably a square hole screen or a round hole screen.

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

the scrubbing in the step 4) is that the first party quartz sand or the first fused silica sand obtained in the step 3) is scrubbed by ultrasonic, preferably the ultrasonic frequency is 10-40 kHz, more preferably the ultrasonic temperature is 20-80 ℃, still more preferably the ultrasonic time is 10-20 min,

it is further preferable that the amount of the scrubbing liquid to be added for scrubbing is 5 to 10 times the mass of the first party silica sand or the first fused silica glass sand,

further preferably, the scrubbing liquid for scrubbing the first quartz sand comprises the following components in parts by mass: 1-20 parts of glacial acetic acid and 100-200 parts of water; or the scrubbing liquid for scrubbing the first fused silica glass sand comprises the following components in parts by mass: oxalic acid 1-20 parts and water 100-200 parts.

12. The method according to any one of items 1 to 3, wherein,

the wet screening in the step 4) is to screen the scrubbed material by adopting a screen with the diameter of 0.1-0.2 mm, preferably 0.15-0.18 mm, and the screen is preferably a square hole screen or a round hole screen.

13. The method according to any one of items 1 to 3, wherein,

the third oversize product, the third undersize product or the fourth undersize product after wet screening are treated by washing with ultrapure water until the pH value of the flushing liquid is 7; and drying to obtain the first high-purity cristobalite, the second high-purity cristobalite or the first high-purity fused silica glass sand and the second high-purity fused silica glass sand.

14. The method according to any one of claims 1 to 3, wherein the pickling is performed with a nitric acid solution having a concentration of 0.1 to 2mol/L, preferably an addition amount of the nitric acid solution to the first undersize product of 1 to 6L/Kg by volume, more preferably a stirring rotation speed of 200 to 500r/min for the pickling, and a stirring pickling time of 1 to 3 hours.

15. The method according to any one of items 1, 3 to 14, wherein,

the granularity of the prepared first high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the sand ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

The granularity of the prepared second high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the second high-purity cristobalite sand ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the prepared first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%;

the granularity of the prepared first fused silica sand is more than 0.18mm, and the amorphous content accounts for more than 95 percent.

16. The method according to any one of items 2, 3 to 14, wherein,

the granularity of the prepared first high-purity fused silica glass sand is more than 0.18mm, and SiO is contained in the sand ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the prepared second high-purity fused silica glass sand is less than 0.18mm, and SiO is contained in the second high-purity fused silica glass sand ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the prepared first quartz sand is smaller than 0.18mm, and the crystalline phase content is more than 98%.

17. The method according to any one of items 3 to 14, wherein,

the granularity of the prepared first high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the sand ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the prepared second high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the second high-purity cristobalite sand ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

first high purity molten stone preparedThe granularity of the quartz glass sand is more than 0.18mm, and the SiO is ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the prepared first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%.

18. A graded cristobalite sand and fused silica glass sand, comprising:

the granularity of the first high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the second high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

The granularity of the first quartz sand is smaller than 0.83mm, and the amorphous content accounts for more than 95%;

the granularity of the first fused silica sand is more than 0.18mm, and the amorphous content is more than 95%.

19. The graded cristobalite sand and fused silica glass sand of item 18, prepared by the method of any one of items 1, 3 to 14.

20. A graded cristobalite sand and fused silica glass sand, comprising:

the granularity of the first high-purity fused silica glass sand is more than 0.18mm, and SiO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the second high-purity fused silica glass sand is less than 0.18mm, siO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the first quartz sand is smaller than 0.18mm, and the crystalline phase content is more than 98%.

21. The graded cristobalite sand and fused silica glass sand of item 20, prepared by the method of any one of items 2, 3 to 14.

22. A graded cristobalite sand and fused silica glass sand, comprising:

The granularity of the first high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the second high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

the granularity of the first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%.

23. The graded cristobalite sand and fused silica glass sand of item 22, prepared by the method of any one of items 3 to 14.

24. Use of the classified cristobalite sand and fused silica glass sand as defined in any one of claims 18 to 23, wherein the first high purity cristobalite sand and the second high purity cristobalite sand are used as metallurgical raw materials, the first cristobalite sand, the first high purity fused silica glass sand and the second high purity fused silica glass sand metallurgical additives, for producing silicon compounds, as blanks for porcelain and refractory materials, the first cristobalite sand and the first cristobalite sand are used as fillers for construction machinery.

Effects of the application

The raw materials of the application are from the waste quartz crucible, and are different from the traditional method for preparing the high-purity fused quartz glass sand by using quartz ore, so that the application not only can realize the recycling of solid wastes, but also is convenient for improving the economic benefit of enterprise production and saves the production cost.

The application adopts high temperature to peel off the crystallization layer, reduces the labor cost, and can remove the organic impurities attached on the surface in the high temperature process.

The application comprehensively utilizes the waste quartz crucible, so that the utilization rate of the waste quartz crucible is more than 95%, the high-purity fused silica glass sand with different particle sizes can be prepared to meet the requirements of different industries, and meanwhile, the crystallization layer is recycled, and the requirements of other industries can be met through grinding and screening.

The high-purity fused silica glass sand and the high-purity fused silica glass sand SiO containing cristobalite produced by the application ₂ The purity can reach 98 percent.

The high-purity cristobalite sand SiO produced by the application ₂ The purity can reach 98% or above, and the recovery rate can reach 96% or above.

The high-purity cristobalite sand SiO produced by the application ₂ The purity can reach 98% and above, the recovery rate can reach 96% and the high-purity cristobalite sand with the particle size smaller than 0.18mm can be used as a raw material or an additive for metallurgy and can also be used for producing silicon compounds in the chemical industry by classifying the high-purity cristobalite sand. The high-purity fused silica glass sand with the grain diameter of 0.18-0.83 mm can be used as a blank of porcelain and refractory materials. The high-purity cristobalite sand with the grain diameter of more than 0.83mm can be used as a filler in construction machinery.

Drawings

Fig. 1 shows a picture of a waste quartz crucible;

FIGS. 2A and 2B show pictures of a spent quartz crucible at a firing temperature of 200 ℃;

FIGS. 3A and 3B show pictures of a spent quartz crucible at a firing temperature of 300 ℃;

FIGS. 4A and 4B show pictures of a spent quartz crucible at a firing temperature of 400 ℃;

fig. 5A and 5B show pictures of a waste quartz crucible at a firing temperature of 450 ℃.

Detailed Description

The following embodiments of the application are merely illustrative of specific embodiments for carrying out the application and are not to be construed as limiting the application. Any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the application are intended to be equivalent arrangements which are within the scope of the application.

Specific embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While specific embodiments of the application are shown in the drawings, it should be understood that the application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

It should be noted that certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will understand that a person may refer to the same component by different names. The description and claims do not identify differences in terms of components, but rather differences in terms of the functionality of the components. As used throughout the specification and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description hereinafter sets forth a preferred embodiment for practicing the application, but is not intended to limit the scope of the application, as the description proceeds with reference to the general principles of the description. The scope of the application is defined by the appended claims.

As used herein, "substantially free" with respect to a particular component is used herein to mean that the particular component is not purposefully formulated into the composition and/or is present as a contaminant or in trace amounts only. Thus, the total amount of the specific components resulting from any accidental contamination of the composition is less than 0.05%, preferably less than 0.01%. Most preferred are compositions wherein the amount of a particular component is undetectable using standard analytical methods.

As used in this specification, "a" or "an" may mean one or more. As used in the claims, the word "a" or "an" when used with the word "comprising" may mean one or more than one.

The term "or" is used in the claims to mean "and/or" unless explicitly indicated to refer to only alternatives or alternatives are mutually exclusive, although the disclosure supports definitions of only alternatives and "and/or". As used herein, "another" may mean at least a second or more.

The application provides a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, wherein the method comprises the following steps of: 1) Crushing and first screening the waste quartz crucible, and respectively collecting first undersize matters and first oversize matters; acid washing the first undersize obtained in the step 1) to obtain first quartz sand; 2) Performing high-temperature roasting treatment on the first oversize product obtained in the step 1) to obtain a mixed material of a surface crystallization layer containing cristobalite sand and fused silica glass sand; 3) Performing self-grinding and second screening on the mixed material obtained in the step 2), taking second undersize to obtain first quartz sand, and taking second oversize to obtain first fused quartz glass sand; 4) Scrubbing the quartz sand of the first party in the step 3), carrying out wet screening to collect third oversize products, and then processing the third oversize products to obtain first high-purity cristobalite sand, and collecting third undersize products, and then processing the third undersize products to obtain second high-purity cristobalite sand.

The application provides a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, wherein the method comprises the following steps of: 1) Crushing and first screening the waste quartz crucible, and respectively collecting first undersize matters and first oversize matters; acid washing the first undersize obtained in the step 1) to obtain first quartz sand; 2) Performing high-temperature roasting treatment on the first oversize product obtained in the step 1) to obtain a mixed material of a surface crystallization layer containing cristobalite sand and fused silica glass sand; 3) Performing self-grinding and second screening on the mixed material obtained in the step 2), taking second undersize to obtain first quartz sand, and taking second oversize to obtain first fused quartz glass sand; 4) Scrubbing the first fused silica glass sand in the step 3), carrying out wet screening to collect fourth oversize products, and then processing to obtain first high-purity fused silica glass sand, and collecting fourth undersize products, and then processing to obtain second high-purity fused silica glass sand.

The application provides a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, wherein the method comprises the following steps of: 1) Crushing and first screening the waste quartz crucible, and respectively collecting first undersize matters and first oversize matters; acid washing the first undersize obtained in the step 1) to obtain first quartz sand; 2) Performing high-temperature roasting treatment on the first oversize product obtained in the step 1) to obtain a mixed material of a surface crystallization layer containing cristobalite sand and fused silica glass sand; 3) Performing self-grinding and second screening on the mixed material obtained in the step 2), taking second undersize to obtain first quartz sand, and taking second oversize to obtain first fused quartz glass sand; 4) Scrubbing the first quartz sand in the step 3), carrying out wet screening to collect third oversize materials, processing to obtain first high-purity cristobalite sand, collecting third undersize materials, processing to obtain second high-purity cristobalite sand, scrubbing the first fused silica glass sand in the step 3), carrying out wet screening to collect fourth oversize materials, processing to obtain first high-purity fused silica glass sand, and collecting fourth undersize materials, processing to obtain second high-purity fused silica glass sand.

The method can comprehensively utilize the waste quartz crucible, and the utilization rate of the waste quartz crucible can reach 100 percent.

In the present application, high purity cristobalite sand refers to a high purity nonmetallic raw material of a certain particle size having a cristobalite crystal phase, and specifically may refer to a high quality quartz raw material having a silica content of 95.0% or preferably 96.0% or preferably 97.0% or more or preferably 98.0% or more.

In the present application, high purity fused silica glass sand refers to high quality amorphous glass having a silica (e.g., quartz, silica) content of 95.0% or preferably 96.0% or preferably 97.0% or preferably 98.0% or more, which has an atomic structure which is long-range disordered, providing its high service temperature and low coefficient of thermal expansion through three-dimensional structural cross-linking.

In the present application, particle size refers to the pore size of the screen through which it can pass during sieving. For example, a particle having a size of greater than 0.83mm, i.e., when screened using a screen having a diameter of 0.83mm, cannot pass through the screen and remain as oversize, while particles having a size of less than 0.83mm can pass through the screen. In the present application, the average particle size is a particle size parameter that characterizes the entire powder. It is generally considered that the average particle size of the undersize obtained when sieving with a sieve having a diameter of 0.83mm is less than 0.83mm, and the average particle size of the undersize is more than 0.83mm.

In the present application, the waste quartz crucible may be derived from any process-generated waste quartz crucible, for example, may be a waste quartz crucible broken due to crystallization, breakage and other stresses in the course of producing a crystalline silicon product by the Czochralski method.

In the present application, crushing may be any crushing means conceivable to those skilled in the art, not limited to machine crushing or manual crushing, and machine crushing may be performed in any commercially available or self-processed mechanical crusher, for example, a hammer crusher, a jaw crusher, a twin roll crusher or a cone crusher, for example, a hammer crusher, a twin roll crusher may be employed to crush the waste quartz crucible to particles having a particle size of less than 10 mm. In the crushing process, the particle materials can be crushed into quartz sand with the particle size of about 0.83mm through crushing, and particles with the particle size lower than the particle size are collected, because the main acting force in the crushing process is extrusion shearing, and the crusher is provided with a fixed ore discharge opening size, and the fused quartz layer can meet normal distribution. So that the particle size distribution range of the target material is mainly concentrated between 0.83 mm.

In the application, screening is to collect fine powder of a devitrified layer peeled and crushed in the crushing process by adopting a pore sieve with a certain diameter. The shape of the hole is not limited as long as the function is satisfied, and for example, the hole may be square, round, triangular or polygonal, or may be a cylindrical hole, a conical hole, a shaped hole, a splined hole or other special holes. In some preferred embodiments of the application, a 0.83mm square or round hole screen or a 0.15 to 0.18mm square or round hole screen is used.

In the application, the first undersize obtained in the step 1) is subjected to acid washing to obtain first quartz sand.

In some specific modes, the pickling is performed by using a nitric acid solution with the concentration of 0.1-2 mol/L, preferably the volume-mass ratio of the added nitric acid solution to the first undersize is 1-6L/Kg, further preferably the stirring rotation speed of the pickling is 200-500 r/min, and the stirring pickling time is 1-3 h; for example, the nitric acid solution concentration may be 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L, 0.9mol/L, 1mol/L, 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L, 1.5mol/L, 1.6mol/L, 1.7mol/L, 1.8mol/L, 1.9mol/L, 2mol/L, or any range therebetween; the volume to mass ratio can be 1L/Kg, 2L/Kg, 3L/Kg, 4L/Kg, 5L/Kg, 6L/Kg or any range therebetween; the stirring rotation speed of the pickling can be 200r/min, 210r/min, 220r/min, 230r/min, 240r/min, 250r/min, 260r/min, 270r/min, 280r/min, 290r/min, 300r/min, 310r/min, 320r/min, 330r/min, 340r/min, 350r/min, 360r/min, 370r/min, 380r/min, 390r/min, 400r/min or any range between the two, and the stirring pickling time can be 1h, 2h, 3h or any range between the two.

In some embodiments, the first screening is performed using a screen having a diameter of 0.7 to 0.9mm, preferably 0.80 to 0-85mm, more preferably 0.83mm, preferably the screen is a square or round hole screen. For example, the first screening diameter may be 0.7mm, 0.71mm, 0.72mm, 0.73mm, 0.74mm, 0.75mm, 0.76mm, 0.78mm, 0.79mm, 0.80mm, 0.81mm, 0.82mm, 0.83mm, 0.84mm, 0.85mm, 0.86mm, 0.88mm, 0.89mm, 0.90mm, or any range therebetween.

In some embodiments, the roasting treatment is to place the obtained waste quartz crucible particles in a high temperature roasting kiln to roast, and the roasting treatment in step 2) is to roast at a temperature of 300-500 ℃, preferably for a time of 1 minute or more, preferably for 1 minute to 1 hour, more preferably for 1 minute to 20 minutes. For example, the baking treatment temperature may be 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 410 ℃, 420 ℃, 430 ℃, 440 ℃, 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, 500 ℃, or any range therebetween; the firing time may be 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.

In the application, the temperature range of high-temperature roasting is that the temperature can meet the minimum temperature condition of falling of a cristobalite layer, and the two substances can be separated by adopting high-temperature roasting and then are separated by sieving because the two substances are different in hardness and body expansion, and the excessive falling temperature can increase unnecessary energy consumption.

In some embodiments, step 2) of the method further comprises water-cooling the calcined first oversize and recovering the calcined first oversize as the mixture after drying, preferably by precipitation of the cooled water for self-grinding. Taking out, quickly cooling in water, recovering hot air as granule for preheating, or precipitating hot water to remove impurities, and using as water for wet self-grinding.

In some embodiments, the autogenous grinding in step 3) is selected from dry autogenous grinding or wet autogenous grinding, preferably autogenous grinding is performed without adding grinding balls at a rotational speed of 300 to 500r/min, more preferably the autogenous grinding time is 1 minute or more, still more preferably the autogenous grinding is 1 minute to 30 minutes, still more preferably the autogenous grinding is 1 minute to 20 minutes. For example, the rotational speed of the self-grinding may be 300r/min, 310r/min, 320r/min, 330r/min, 340r/min, 350r/min, 360r/min, 370r/min, 380r/min, 390r/min, 400r/min, 410r/min, 420r/min, 430r/min, 440r/min, 450r/min, 460r/min, 470r/min, 480r/min, 490r/min, 500r/min, or any range therebetween; the self-milling time may 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.

In the present application, the self-grinding may be classified as dry or wet self-grinding. The self-grinding without grinding balls is selected to reduce the introduction of impurities due to abrasion on the one hand, and on the other hand, the grinding balls are spherical, and under the high-speed rotation, the grinding peeling acting force mainly generated is unfavorable for the dissociation of high-hardness materials, the shapes of the samples are different, the special-shaped structures collide with each other under the high-speed movement, so that the materials are preferentially broken from the stress concentration areas, the stress points of the materials are concentrated in bubbles, the materials are broken along the edges of the bubbles, and the better grinding effect can be achieved. Meanwhile, as the target materials in the application are the cristobalite crystallization layer and the fused quartz, the hardness and the brittleness of the cristobalite crystallization layer are greatly different, and the selection of the self-grinding process can enable the fused quartz with high hardness to form a selective grinding effect on the cristobalite crystallization layer with low hardness, so that the cristobalite crystallization layer sample is preferentially ground to finer granularity, and the subsequent treatment is convenient.

In the application, a stirring tank is adopted for dry self-grinding, the rotating speed is 300-500 r/min, and the self-grinding time is 1-15 min. The purpose of selecting the range of the dry self-grinding is to not only meet the effect of selective grinding, but also avoid the excessively long grinding time to reduce the yield of fused quartz on the screen.

In the application, a stirring tank is adopted for wet self-grinding, the rotating speed is 300-500 r/min, the self-grinding time is 10-30 min, and self-grinding water is adopted as tap water. The self-grinding water is used as tap water, and the purpose of selecting the range is to not only meet the effect of selective grinding, but also avoid the excessively long grinding time to reduce the yield of fused quartz on the screen.

In some embodiments, the second screening is performed using a screen having a diameter of 0.1 to 0.2mm, preferably 0.15 to 0.18mm, preferably the screen is a square or round mesh screen; for example, the diameter may be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, or any range therebetween.

In the present application, the scrubbing is any scrubbing means known to those skilled in the art, as long as the purpose is achieved. The scrubbing mode can be ultrasonic scrubbing, mechanical scrubbing or other scrubbing modes. In the parameter selection of scrubbing, the person skilled in the art can choose according to the actual situation, as long as the purpose is achieved.

In some specific modes, the scrubbing in the step 4) is that the first quartz sand or the first fused silica sand obtained in the step 3) is scrubbed by ultrasonic, preferably the ultrasonic frequency is 10-40 kHz, further preferably the ultrasonic temperature is 20-80 ℃, further preferably the ultrasonic time is 10-20 min; for example, the ultrasonic frequency may be 10kHz, 11kHz, 12kHz, 13kHz, 14kHz, 15kHz, 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz, 25kHz, 26kHz, 27kHz, 28kHz, 29kHz, 30kHz, 31kHz, 32kHz, 33kHz, 34kHz, 35kHz, 36kHz, 37kHz, 38kHz, 39kHz, 40kHz or any range therebetween; the ultrasonic temperature may be 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ or any range therebetween; the ultrasound time may be 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min, or any range therebetween.

In the present application, the frequency and temperature selection of the ultrasound in step 4) is based on a combination of related experiments and in view of a better implementation in industry. Scrubbing has the effect of preliminary purification, and can remove impurities introduced in the self-grinding process or impurities carried by the materials. The ultrasound can be used to remove suspended impurities and dust therein. The scrubbing and ultrasonic cleaning are synchronously carried out, so that a better removing effect can be achieved. The purpose of glacial acetic acid is to adopt weak organic acid to reduce environmental pollution, and on the other hand, glacial acetic acid has a dissolving effect on iron, calcium, barium and the like, so that certain impurity removing effect can be achieved.

In some embodiments, the amount of the scrubbing liquid used for scrubbing is 5 to 10 times the mass of the first party silica sand or the first fused silica glass sand, and may be, for example, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, or any range therebetween.

In the present application, the acid medium used in the scrubbing liquid is not limited at all, and may be a weak acid, for example, glacial acetic acid, oxalic acid, ascorbic acid, citric acid, hydrogen sulfate, hydrogen cyanide, hydrofluoric acid, phosphoric acid, boric acid, formic acid or other weak acids.

In some specific embodiments, the scrubbing liquid for scrubbing the first quartz sand includes, in parts by mass: 1-20 parts of glacial acetic acid and 100-200 parts of water; for example, glacial acetic acid may 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 may 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 silica glass sand comprises the following components in parts by mass: oxalic acid 1-20 parts, water 100-200 parts; for example, oxalic acid may 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 may 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.

The cleaning liquid is selected, so that the cost is more economical and the medicament waste caused by the difficulty in dissolving excessive glacial acetic acid is avoided while the cleaning condition is met, and the consumption of the glacial acetic acid can be changed according to the material quantity and the impurity content.

In some embodiments, the wet sieving in step 4) is performed by sieving the scrubbed material with a sieve having a diameter of 0.1 to 0.2mm, preferably 0.15 to 0.18mm, for example, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, or any range therebetween; preferably, the screen is a square or round mesh screen.

In some embodiments, treating the wet screened third oversize, third undersize, or fourth undersize refers to washing with ultrapure water until the rinse solution has a pH of 7; and drying to obtain the first high-purity cristobalite, the second high-purity cristobalite or the first high-purity fused silica glass sand and the second high-purity fused silica glass sand.

In a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, a first high-purity cristobalite sand having a particle size of less than 0.18mm and SiO is prepared ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared second high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the second high-purity cristobalite sand ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%; the granularity of the prepared first fused silica sand is more than 0.18mm, and the amorphous content accounts for more than 95 percent.

In a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, a first high-purity fused silica glass sand having a particle size of more than 0.18mm and SiO is prepared ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared second high-purity fused silica glass sand is less than 0.18mm, and SiO is contained in the second high-purity fused silica glass sand ₂ The content is 98 percent to 99.9 percent, the amorphous content accounts for more than 95 percent,the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%; the granularity of the prepared first quartz sand is smaller than 0.18mm, and the crystalline phase content is more than 98%.

In a method for preparing cristobalite sand and fused silica glass sand by using a waste quartz crucible, a first high-purity cristobalite sand having a particle size of less than 0.18mm and SiO is prepared ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared second high-purity cristobalite sand is less than 0.18mm, and SiO is contained in the second high-purity cristobalite sand ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared first high-purity fused silica glass sand is more than 0.18mm, and SiO is contained in the sand ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared second high-purity fused silica glass sand is less than 0.18mm, and SiO is contained in the second high-purity fused silica glass sand ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the prepared first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%.

The present application provides a graded cristobalite sand and fused silica glass sand, comprising: the granularity of the first high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the second high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is above 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the first quartz sand is smaller than 0.83mm, and the amorphous content accounts for more than 95%; the granularity of the first fused silica sand is more than 0.18mm, and the amorphous content is more than 95%. Preferably, it is prepared by a method of preparing cristobalite sand and fused silica glass sand using a waste quartz crucible.

The present application provides a graded cristobalite sand and fused silica glass sand, comprising: the first high-purity fused silica sand has a particle size of greater than 0.18mm，SiO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the second high-purity fused silica glass sand is less than 0.18mm, siO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the first quartz sand is smaller than 0.83mm, and the amorphous content accounts for more than 95%; the granularity of the first quartz sand is smaller than 0.18mm, and the crystalline phase content is more than 98%. Preferably, it is prepared by a method of preparing cristobalite sand and fused silica glass sand using a waste quartz crucible.

The present application provides a graded cristobalite sand and fused silica glass sand, comprising: the granularity of the first high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the second high-purity cristobalite sand is less than 0.18mm, and SiO ₂ The content is 98% -99.9%, the crystalline phase content is more than 98%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the first high-purity fused silica glass sand is more than 0.18mm, and SiO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the second high-purity fused silica glass sand is less than 0.18mm, siO ₂ The content is 98% -99.9%, the amorphous content accounts for more than 95%, and the content of Ba is lower than 15 mg/kg of high-purity cristobalite sand; the granularity of the first quartz sand is smaller than 0.83mm, and the amorphous content is more than 95%. Preferably, it is prepared by a method of preparing cristobalite sand and fused silica glass sand using a waste quartz crucible.

In the present application, the detection of the crystal phase ratio in the obtained cristobalite sand and fused silica sand is performed by using an X-ray diffractometer, and a person skilled in the art can perform the detection based on the instruction of the instrument.

In the present application, the detection of the amorphous phase ratio in the obtained cristobalite sand and fused silica sand is performed by using an X-ray diffractometer, and a person skilled in the art can perform the detection based on the instruction of the apparatus.

In the present application, the content of each element in the cristobalite sand and the fused silica glass sand is detected by the ICP-OES method, but other methods known to those skilled in the art may be employed.

The present application provides the use of the above classified cristobalite sand and fused silica glass sand, wherein the first high purity cristobalite sand and the second high purity cristobalite sand are used as metallurgical raw materials, the first cristobalite sand, the first high purity fused silica glass sand, and the second high purity fused silica glass sand metallurgical additives, for producing silicon compounds, as blanks for porcelain and refractory materials, and the first cristobalite sand are used as fillers for construction machinery.

The method can fully utilize the waste quartz crucible, can fully recycle more than 95% of the components of the waste quartz crucible, and really changes waste into valuable, and is fully recycled.

Examples

The materials used in the test and the test methods are described generally and/or specifically in the examples which follow,% represents wt%, i.e. weight percent, unless otherwise specified. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.

High temperature calcination experiment

In the high temperature firing experiment, as shown in fig. 1, many experiments were tried in designing the temperature of high temperature firing with respect to the waste quartz crucible. The method comprises the following steps: the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, and the main component of the crystallization layer is cristobalite phase. Firstly, placing a waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to be within 10mm, then, further crushing the waste quartz crucible by a double-roll crusher, collecting oversize materials which do not pass through a square hole or round hole sieve with the diameter of 0.83mm, peeling off the crushed oversize materials in the crushing process to obtain waste quartz crucible crystallization layer fine powder with the granularity of more than 0.83mm, placing the waste quartz crucible crystallization layer fine powder into a high-temperature roasting kiln for roasting at the temperature of 200 ℃ for 20min, rapidly taking out the waste quartz crucible crystallization layer fine powder after roasting is finished, and pouring the waste quartz crucible crystallization layer fine powder into cooling water for cooling. Applicants found that when high temperature firing was 200 ℃, the devitrified layer was not eventually separated from the fused silica as shown in fig. 2; FIG. 2A shows the temperature of the waste quartz crucible at a temperature of Wen Lugong to 200℃for 20min, and FIG. 2B shows the temperature of 200℃for 20min, without separating the devitrified layer from the fused quartz.

Similarly, applicants have found that when fired at 300 ℃ at high temperatures, the devitrified layer is eventually not separated from the fused silica, as shown in fig. 3; FIG. 3A shows the temperature of the waste quartz crucible at a temperature of Wen Lugong to 300℃for 20min, and FIG. 3B shows the temperature of 300℃for 20min, without separating the devitrified layer from the fused quartz.

Similarly, applicants have found that when fired at 400 ℃ at high temperatures, the devitrified layer can eventually be separated from the fused silica, as shown in fig. 4; FIG. 4A shows the temperature at a temperature of Wen Lugong to 400℃for 10min, and FIG. 4B shows the temperature at 400℃for 10min, with the devitrified layer of the spent quartz crucible separated from the fused quartz.

Similarly, applicants have found that when fired at a high temperature of 450 ℃, the devitrified layer can eventually be separated from the fused silica, as shown in FIG. 5; FIG. 5A shows the temperature at a height of Wen Lugong to 450℃for 5min, and FIG. 5B shows the temperature at 450℃for 5min, with the devitrified layer of the spent quartz crucible separated from the fused quartz.

Example 1 a method for preparing cristobalite sand and fused silica glass sand by separating a crystallization layer from a waste quartz crucible, comprising the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 1.

TABLE 1 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	58.97	48.3	3.13	27.71	9.5	0.34	12.54	20.1	98.13
Fused silica	47.46	41.1	2.14	25.79	8.54	0.5	17.49	13.04	98.81

Wherein SiO is removed in Table 1 and tables 2 to 20 below ₂ The units of the other elements are ppm.

Firstly, placing the waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to 10mm, then passing through a double-roller crusher, further crushing, and collecting oversize materials which are not stripped and crushed in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm, thereby obtaining waste quartz crucible crystallization layer fine powder with the particle size of more than 0.83 mm.

Acid washing the waste quartz crucible crystallization layer fine powder with the grain diameter smaller than 0.83mm, namely acid washing the undersize material, placing the waste quartz crucible crystallization layer fine powder into an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid washing while stirring, wherein the volume mass ratio of the adding amount of the nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid washing time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain quartz sand.

Placing the waste quartz crucible crystallization layer fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 300 ℃, the roasting time is 20min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible crystallization layer fine powder into cooling water for cooling. Carrying out dry self-grinding on the waste quartz crucible crystallization layer fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible cristobalite sand into a stirring tank, setting the rotating speed to be 300r/min, and after the self-grinding time is over, enriching the crystallization layer fine powder stripped and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18 mm;

A first part:

taking undersize with the diameter smaller than 0.18mm after self-grinding, namely 550g of crude high-purity cristobalite sand. Placing coarse high-purity cristobalite sand into an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of oxalic acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the coarse high-purity cristobalite sand, the temperature is set to be 60 ℃, the scrubbing time is set to be 10min, the ultrasonic power is set to be 10Khz, and after the ultrasonic cleaning is finished, the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes is enriched by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the undersize is extracted, thus 500g of refined cristobalite sand is obtained.

Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying with hot air to obtain 498g of finished cristobalite sand and SiO of the finished cristobalite sand ₂ The content of Ba is 98.71%, and the content of Ba is 9.51mg/kg.

Placing the oversize product which is subjected to ultrasonic cleaning and sieving and has the diameter of more than 0.18mm into an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize product is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain quartz sand.

A second part: the oversize product with the diameter of more than 0.18mm after self-grinding is taken, and 450g of crude fused silica sand is obtained. Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of oxalic acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the crude fused silica sand, the temperature is set to be 60 ℃, the scrubbing time is set to be 10min, the ultrasonic power is set to be 10Khz, after the ultrasonic cleaning is finished, the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes is enriched by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the oversize is extracted, thus 447g of the refined fused silica sand is obtained.

Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 445g of finished fused silica sand and SiO of the finished fused silica sand ₂ The content is 98.91 percent and the Ba content is 11.11mg/kg.

Placing the undersize material which is subjected to ultrasonic cleaning and has the diameter of less than 0.18mm in an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

The impurity levels detected using the ICP-OES method are shown in Table 2.

TABLE 2 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Cristobalite sand	30.41	21.5	0.43	17.3	4.47	0.32	12.18	9.51	99.71
Fused silica glass sand	35.98	24.91	0.69	11.43	6.71	0.51	13.44	11.11	98.91

Example 2 method for preparing cristobalite sand and fused silica glass sand by separating crystallization layer from waste quartz crucible

The method comprises the following steps:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 3.

TABLE 3 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	43.2	38.13	4.23	30.01	6.37	1.91	13.94	19.71	98.43
Fused silica	36.7	30.11	2.13	27.71	5.01	1	9.95	10.2	98.87

Firstly, placing a waste quartz crucible in a hammer crusher, crushing most of the waste quartz crucible to 10mm, then passing through a double-roller crusher, further crushing, separating and crushing the fine powder of the crystallization layer in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm, enriching, and taking oversize to obtain waste quartz crucible sand with the particle size of more than 0.83 mm.

Acid washing the waste quartz crucible crystallization layer fine powder with the grain diameter smaller than 0.83mm, namely acid washing the undersize material, placing the waste quartz crucible crystallization layer fine powder into an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid washing while stirring, wherein the volume mass ratio of the adding amount of the nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid washing time is 1-3 h; after acid leaching reaction, filtering the reaction product, flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7, putting the flushed sample into a baking oven for drying at 100-120 ℃ for 6-10h, and obtaining quartz sand.

Placing the waste quartz crucible crystallization layer fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 320 ℃, the roasting time is 15min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible crystallization layer fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible crystallization layer fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible cristobalite sand into a stirring tank, setting the rotating speed to be 300r/min, and after the self-grinding time is over, enriching the crystallization layer fine powder stripped and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18 mm;

a first part:

taking undersize products with the diameter smaller than 0.18mm after self-grinding,i.e. 545g of crude high-purity cristobalite sand. Placing coarse high-purity cristobalite sand into an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of citric acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the coarse high-purity cristobalite sand, the temperature is set to 65 ℃, the scrubbing time is 12min, the ultrasonic power is 10Khz, after the ultrasonic cleaning is finished, the coarse high-purity cristobalite sand is subjected to enrichment of fine powder of a crystallization layer stripped and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the undersize is taken to obtain 543g of refined high-purity cristobalite sand. Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying with hot air to obtain 540g of finished cristobalite sand and SiO of the finished cristobalite sand ₂ The content is 98.78%, and the Ba content is 9.13mg/kg.

Placing the oversize material with the diameter being larger than 0.18mm after ultrasonic cleaning in an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

A second part:

the screen material with the diameter larger than 0.18mm after self-grinding is taken to obtain 455g of crude fused silica sand. Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of citric acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the crude fused silica sand, the temperature is set to 65 ℃, the scrubbing time is set to 12min, the ultrasonic power is set to 10Khz, after the ultrasonic cleaning is finished, the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes is enriched by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the oversize is extracted, namely 452g of refined fused silica sand. Washing the refined fused silica sand with ultrapure water until the pH of the washing liquid is neutral, and drying the washing liquid with hot air to obtain the finished product of fused stone 450g of quartz glass sand and high-purity fused quartz glass sand ₂ The content is 99.15 percent, and the content of Ba is 12.52mg/kg.

Taking undersize products with the diameter smaller than 0.18mm after ultrasonic cleaning, obtaining undersize products with the diameter smaller than 0.18mm, placing the undersize products into an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume mass ratio of the added nitric acid solution to the undersize products is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

The impurity levels detected using the ICP-OES method are shown in Table 4.

TABLE 4 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Cristobalite sand	24.98	17.45	0.4	14.07	3.47	0.83	8.14	9.51	98.78
Fused silica glass sand	23.9	17.91	0.4	9.99.	4.41	0.47	9.91	11.11	99.15

Example 3 method for preparing cristobalite sand and fused silica glass sand by separating crystallization layer from waste quartz crucible

The method comprises the following steps:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 5.

TABLE 5 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	47.3	37.13	2.2	23.91	6	0.99	14.88	17.98	98.37
Fused silica	36.7	32.32	2.4	19.41	4.99	0.99	11.01	11.41	98.79

Firstly placing the waste quartz crucible in a hammer crusher, crushing most of the waste quartz crucible to 10mm, then passing through a double-roller crusher, further crushing, enriching the fine powder of the devitrified layer peeled and crushed in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm, taking the oversize material, obtaining the sand fine powder of the waste quartz crucible with the particle diameter of more than 0.83mm,

acid washing is carried out on waste quartz crucible crystallization layer fine powder with the grain diameter smaller than 0.83mm, namely undersize products, undersize products with the diameter smaller than 0.18mm are taken and placed in an acid-resistant reaction kettle, nitric acid solution with the concentration of 0.1-2 mol/L is added while stirring for acid leaching, the volume mass ratio of the adding amount of the nitric acid solution to the undersize products is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after acid leaching reaction, filtering the reaction product, flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7, putting the flushed sample into a baking oven for drying at 100-120 ℃ for 6-10h, and obtaining quartz sand.

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 400 ℃, the roasting time is 10min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out wet self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, adding 5000mL of water into a stirring tank, setting the rotating speed to 600r/min, and carrying out self-grinding for 18min, wherein after the self-grinding is finished, the fine powder of a crystallization layer stripped and ground in the heating roasting and self-grinding processes is enriched by adopting a square hole or round hole sieve with the diameter of 0.18 mm;

a first part:

taking undersize with the diameter smaller than 0.18mm after self-grinding, namely 570g of coarse high-purity cristobalite sand. The cristobalite sand was transferred to an ultrasonic cleaner. Placing coarse high-purity cristobalite sand into an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of glacial acetic acid and 2000mL of water, adding the wiping solution, immersing a sample in the wiping solution, setting the temperature to 80 ℃, the wiping time to 15min, and the ultrasonic power to 20Khz, enriching the fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking screen bottoms, namely 567g of refined high-purity cristobalite sand. Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying with hot air to obtain 565g of finished cristobalite sand, which is SiO ₂ The content of Ba is 99.61% and the content of Ba is 8.71mg/kg.

Placing the oversize material which is subjected to ultrasonic cleaning and has the diameter of more than 0.18mm in an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

A second part:

the oversize product with the diameter larger than 0.18mm after self-grinding is taken to obtain 430g of crude fused silica sand. Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a cleaning solution, adding 200g of glacial acetic acid and 2000mL of water, adding the cleaning solution, immersing the sample in the cleaning solution, setting the temperature to 80 ℃, cleaning for 15min, performing ultrasonic power to 20Khz, concentrating the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking the oversize product, namely 425g of refined fused silica sand. The refined fused silica sand is fed with ultrapure water Flushing until the pH value of flushing liquid is neutral, and drying the flushing liquid by hot air to obtain 418g of finished fused silica glass sand, namely SiO of the finished fused silica glass sand ₂ The content of Ba is 99.81 percent and the content of Ba is 11.71mg/kg.

Placing undersize products with the diameter smaller than 0.18mm after ultrasonic cleaning in an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize products is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

The impurity levels detected using the ICP-OES method are shown in Table 6.

TABLE 6 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Cristobalite sand	25.31	21.55	0.43	20.07	4.47	0.8	10	8.71	99.61
Fused silica glass sand	23.9	17.91	0.4	9.99.	4.41	0.47	9.91	11.11	99.15

Example 4 method for preparing cristobalite sand and fused silica glass sand by separating crystallization layer from waste quartz crucible

The method comprises the following steps:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 7.

TABLE 7 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	47	32.1	2.12	20.92	5.1	1.02	14.1	16.99	98.66
Fused silica	35.41	29.74	2	17.41	4.78	0.87	9.01	10	98.81

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 500 ℃, the roasting time is 3min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible cristobalite sand into a stirring tank, setting the rotating speed to be 300r/min, carrying out self-grinding for 20min, and enriching the fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished;

a first part:

taking undersize with the diameter smaller than 0.18mm after self-grinding, namely 570g of coarse high-purity cristobalite sand. Wet self-grinding is carried out on coarse high-purity cristobalite sand, 5000mL of water is added into a stirring tank, the rotating speed is set to be 500r/min, the self-grinding time is set to be 20min, and after the self-grinding time is finished, the cristobalite sand is transferred into an ultrasonic cleaning instrument. Placing the waste quartz crucible in an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of glacial acetic acid and 2000mL of water, adding the wiping solution, immersing the sample, setting the temperature to 80 ℃, scrubbing for 20min, enabling the ultrasonic power to be 30Khz, removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking screen residues, namely 574g of refined high-purity cristobalite sand. Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying with hot air to obtain 570g of finished cristobalite sand and SiO of the finished cristobalite sand ₂ The content of Ba is 99.96%, and the content of Ba is 8.13mg/kg.

Placing the oversize material with the diameter larger than 0.18mm after ultrasonic cleaning in an acid-resistant reaction kettle, adding nitric acid solution with the concentration of 0.1-2 mol/L for acid leaching while stirring, wherein the volume-mass ratio of the added nitric acid solution to the undersize material is 1-6L/Kg, the stirring rotating speed is 100-300 r/min, and the stirring acid leaching time is 1-3 h; after the acid leaching reaction, filtering the reaction product, and flushing filter residues with ultrapure water until the pH value of flushing liquid is 6.5-7; and (3) placing the washed sample into an oven for drying at 100-120 ℃ for 6-10 hours to obtain a high-purity quartz glass sand filter cake containing cristobalite.

A second part:

oversize material with the diameter of more than 0.18mm after self-grinding is taken to be coarse fused silica sand) 420g. Wet self-grinding the crude fused silica sand, adding 5000mL of water into a stirring tank, setting the rotating speed to be 500r/min, and transferring the crude fused silica sand into an ultrasonic cleaning instrument after the self-grinding time is over, wherein the self-grinding time is 20 min. A scrub solution was prepared, 200g of glacial acetic acid and 2000mL of water were added, the scrub solution was added without passing through the sample,setting the temperature at 80 ℃, scrubbing for 20min, carrying out ultrasonic power at 30Khz, removing fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking oversize materials, namely 415g of refined fused silica sand. Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 413g of finished fused silica sand and SiO of the finished fused silica sand ₂ The content is 99.98 percent and the Ba content is 8mg/kg.

The impurity levels detected by the ICP-OES method are shown in Table 8.

TABLE 8 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Cristobalite sand	20.31	19.78	0.37	14.71	2.71	0.51	5	8.13	99.96
Fused silica glass sand	24.9	18.91	0.14	6.19	2.31	0.31	7.1	8	99.98

Example 5 a method for preparing cristobalite sand and fused silica glass sand by separating a crystallization layer from a waste quartz crucible,

the method comprises the following steps:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 9.

TABLE 9 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	58.2	47.3	3	28	8.95	0.3	9.9	18.1	99.39
Fused silica	44.7	42.4	1	25.8	8.65	0.5	17.69	11.1	99.85

Firstly, placing a waste quartz crucible in a hammer crusher, crushing most of the waste quartz crucible to 10mm, then, further crushing the waste quartz crucible by a double-roller crusher, removing fine powder of a crystallization layer which is peeled and crushed in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm, and taking oversize materials to obtain waste quartz crucible sand fine powder with the particle size of more than 0.83 mm.

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 300 ℃, the roasting time is 20min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible quartz glass sand into a stirring tank, setting the rotating speed to be 200r/min, carrying out self-grinding for 5min, and removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished;

a first part:

the oversize product with the diameter of more than 0.18mm after self-grinding is taken to obtain 950g of crude fused silica sand. Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of citric acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the crude fused silica sand, the temperature is set to be 60 ℃, the scrubbing time is set to be 15min, the ultrasonic power is set to be 10Khz, after the ultrasonic cleaning is finished, the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes is removed by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the oversize is obtained to obtain 930g of refined fused silica sand. Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 925g of finished fused silica sand, namely SiO of the finished fused silica sand ₂ The content of Ba is 99.91% and the content of Ba is 9.5mg/kg.

A second part:

and taking undersize with the diameter smaller than 0.18mm after self-grinding, namely 50g of crude high-purity cristobalite sand. Placing coarse high-purity cristobalite sand into an ultrasonic cleaning instrument, preparing wiping liquid, adding 200g of citric acid and 2000mL of water, addingThe adding amount of the cleaning liquid is 5 times of the mass of the coarse high-purity cristobalite sand, the temperature is set at 60 ℃, the scrubbing time is set at 15min, the ultrasonic power is set at 10Khz, after the ultrasonic cleaning is finished, the fine powder of the crystallization layer peeled and ground in the heating roasting and self-grinding processes is removed by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the screen residue is taken out, namely 48g of refined high-purity cristobalite sand. Washing the refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying the washing liquid with hot air to obtain 46g of finished cristobalite sand and SiO of the finished cristobalite sand ₂ The content of Ba is 99.83 percent and the content of Ba is 14.78mg/kg.

The impurity levels detected using the ICP-OES method are shown in Table 10.

TABLE 10 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Fused silica glass sand	35.10	27.5	0.53	20.30	6.45	0.49	13.33	9.50	99.91
Cristobalite sand	36.98	30.56	1.19	24.61	7.98	0.77	14.92	12.10	99.83

Example 6 a method for preparing cristobalite sand and fused silica glass sand by separating a crystallization layer from a waste quartz crucible, the method comprising the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 11.

TABLE 11 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	52.20	46.13	2.71	28.13	8.55	0.60	10.97	17.45	99.16
Fused silica	46.70	39.92	1.71	23.78	8.77	0.53	16.95	11.20	99.85

Firstly placing the waste quartz crucible in a hammer crusher, crushing most of the waste quartz crucible to 10mm, then passing through a double-roller crusher, further crushing, removing fine powder of a crystallization layer peeled and crushed in the crushing process through a square hole or round hole sieve with the diameter of 0.83mm, taking oversize materials, obtaining waste quartz crucible sand fine powder with the particle size of more than 0.83mm,

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 300 ℃, the roasting time is 15min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible quartz glass sand into a stirring tank, setting the rotating speed to be 200r/min, carrying out self-grinding for 10min, and removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished;

a first part:

the oversize product with the diameter of more than 0.18mm after self-grinding is 975g of crude fused silica sand. Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a wiping solution, adding 200g of oxalic acid and 2000mL of water, wherein the adding amount of the wiping solution is 5 times the mass of the crude fused silica sand, the temperature is set to be 70 ℃, the scrubbing time is set to be 15min, the ultrasonic power is set to be 10Khz, after the ultrasonic cleaning is finished, the fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes is removed by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the oversize is extracted, thus 955g of the refined fused silica sand is obtained. Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 950g of finished fused silica sand and SiO of the finished fused silica sand ₂ The content of Ba is 99.93 percent and the content of Ba is 9.11mg/kg.

A second part:

the undersize product with the diameter smaller than 0.18mm after self-grinding is taken, and 25g of crude high-purity cristobalite sand is obtained. Placing coarse high-purity cristobalite sand into an ultrasonic cleaning instrument, preparing wiping liquid, and adding 200g of grassAcid and 2000mL of water, the addition amount of the wiping solution is 5 times of the mass of the coarse high-purity cristobalite sand, the temperature is set at 70 ℃, the scrubbing time is set at 15min, the ultrasonic power is set at 10Khz, after the ultrasonic cleaning is finished, the ultrasonic cleaning is carried out, the fine powder of the crystallization layer peeled and ground in the heating roasting and self-grinding processes is removed by adopting a square hole or round hole sieve with the diameter of 0.18mm, and the screened product is taken out, namely 23g of refined high-purity cristobalite sand. Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying the washing liquid with hot air to obtain 22g of finished cristobalite sand and SiO of finished fused quartz glass sand ₂ The content is 99.74 percent and the Ba content is 13.16mg/kg.

The impurity levels detected using the ICP-OES method are shown in Table 12.

TABLE 12 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Fused silica glass sand	36.11	25.45	0.48	20.3	5.47	0.47	12.44	9.5	99.93
Cristobalite sand	37.98	27.7	0.78	21.11	6.98	0.77	13.93	13.16	99.74

Example 7 a method for preparing cristobalite sand and fused silica glass sand by separating a crystallization layer from a waste quartz crucible, the method comprising the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 13.

TABLE 13 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	48.2	45.77	3.13	27.91	7.77	1	11.37	18.45	99.17
Fused silica	44.7	37.44	2.22	24.01	5.34	0.7	17.44	11.2	99.79

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 400 ℃, the roasting time is 10min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling. Carrying out wet self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible quartz glass sand into a stirring tank, adding 2000mL of tap water, setting the rotating speed to be 500r/min, and carrying out self-grinding for 15min, wherein after the self-grinding is finished, the waste quartz crucible sand fine powder is removed through a square hole or round hole sieve with the diameter of 0.18mm, and stripping and grinding the fine powder of a crystallization layer in the heating roasting and self-grinding processes;

A first part:

the oversize product with the diameter larger than 0.18mm after self-grinding is 960g of crude fused silica sand (namely first fused silica sand). Placing the crude fused silica sand in an ultrasonic cleaning instrument, preparing a cleaning solution, adding 200g of glacial acetic acid and 2000mL of water, adding the cleaning solution, immersing the sample in the cleaning solution, setting the temperature to 80 ℃, cleaning for 15min, performing ultrasonic power to 20Khz, removing fine powder of a devitrified layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking oversize products, namely 950g of refined fused silica sand. Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 940g of finished fused silica sand and SiO of the finished fused silica sand ₂ The content is 99.94 percent, and the content of Ba is 10.75mg/kg.

A second part:

the undersize product with the diameter smaller than 0.18mm after self-grinding is taken to obtain 40g of crude high-purity cristobalite sand (namely first-party quartz sand). Placing coarse high-purity cristobalite sand in an ultrasonic cleaning instrument, and preparingPlacing wiping liquid, adding 200g of glacial acetic acid and 2000mL of water, adding the wiping liquid, immersing the sample, setting the temperature to 80 ℃, scrubbing for 15min, performing ultrasonic power to 20Khz, removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking the undersize, namely 39g of refined high-purity cristobalite sand. Washing refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying with hot air to obtain finished cristobalite sand 37g and SiO of the finished cristobalite sand ₂ The content of Ba is 99.83% and the content of Ba is 9.61mg/kg.

The impurity levels detected using the ICP-OES method are shown in Table 14.

TABLE 14 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Fused silica glass sand	33.43	20.94	0.5	17.43	3.12	0.51	9.71	10.75	99.94
Cristobalite sand	29.11	19.51	0.15	18.1	5.41	0.77	10.71	9.61	99.83

Example 8 a method for preparing cristobalite sand fused silica glass sand by separating a crystallization layer from a waste quartz crucible, the method comprising the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements detected by an ICP-OES method is shown in table 15.

TABLE 15 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	41.2	40.77	2.51	24.13	5.41	1	12.1	17.3	99.73
Fused silica	39.7	37.41	1.79	20.43	3.91	0.68	15.44	11.12	99.91

Firstly, placing a waste quartz crucible in a hammer crusher, crushing most of the waste quartz crucible to 10mm, then passing through a double-roller crusher, further crushing, and removing fine powder of a crystallization layer peeled and crushed in the crushing process through a square hole or round hole sieve with the diameter of 0.83mm to obtain waste quartz crucible sand fine powder with the particle size of more than 0.83 mm.

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 500 ℃, the roasting time is 5min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 1000g of waste quartz crucible quartz glass sand into a stirring tank, setting the rotating speed to be 200r/min, carrying out self-grinding for 15min, and removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished;

a first part:

the oversize product with the diameter of more than 0.18mm after self-grinding is taken to be 980g of crude fused silica sand (namely first fused silica sand). Wet self-grinding is carried out on the crude fused silica sand, 5000mL of water is added into a stirring tank, the rotating speed is set to be 500r/min, the self-grinding time is set to be 20min, and after the self-grinding time is over, the quartz glass sand is transferred into an ultrasonic cleaning instrument. Preparing a wiping solution, adding 200g of oxalic acid and 2000mL of water, adding the wiping solution, immersing the sample, setting the temperature to 80 ℃, scrubbing for 20min, performing ultrasonic power to 20Khz, removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking oversize products, namely 970g of refined fused silica sand. Rinsing the refined fused silica sand with ultrapure water until the pH of the rinsing liquid is neutral, and drying the rinsing liquid with hot air to obtain 965g of finished fused silica sand and SiO of the finished fused silica sand ₂ The content of Ba is 99.98%, and the content of Ba is 6.73mg/kg.

A second part:

the diameter of the product is smaller than 0.18m after self-grindingThe undersize of m is 21g of crude high-purity cristobalite sand. Wet self-grinding the coarse high-purity cristobalite sand, adding 5000mL of water into a stirring tank, setting the rotating speed to be 500r/min, and transferring the quartz sand into an ultrasonic cleaning instrument after the self-grinding time is over, wherein the self-grinding time is 20 min. Preparing a wiping solution, adding 200g of oxalic acid and 2000mL of water, adding the wiping solution, immersing the sample, setting the temperature to 80 ℃, scrubbing for 20min, performing ultrasonic power to 20Khz, removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after ultrasonic cleaning is finished, and taking undersize, namely 20g of refined high-purity cristobalite sand. Washing the refined high-purity cristobalite sand with ultrapure water until the pH of the washing liquid is neutral, and drying the washing liquid with hot air to obtain 19g of finished cristobalite sand and SiO of the finished cristobalite sand ₂ The content of Ba is 99.96%, and the content of Ba is 9.51mg/kg.

The impurity levels detected using the ICP-OES method are shown in Table 16.

TABLE 16 impurity element content (ppm) of cristobalite sand and fused silica glass sand

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Fused silica glass sand	29.47	15.91	0.44	15	2.13	0.31	7.52	6.73	99.98
Cristobalite sand	29.11	19.51	0.15	18.1	5.41	0.77	10.71	9.51	99.96

Comparative example 1 the method comprises the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements is shown in table 17 (detected by using an ICP-OES method).

TABLE 17 impurity element content (ppm) of waste quartz crucible

Firstly, placing a waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to 15mm, then passing through a double-roller crusher, further crushing, collecting fine powder of a crystallization layer which is peeled and crushed in the crushing process through a square hole or round hole sieve with the diameter of 0.83mm, and taking oversize materials to obtain waste quartz crucible sand fine powder with the particle size of more than 0.83 mm; taking the undersize to obtain waste quartz crucible sand fine powder with the particle size smaller than 0.83 mm.

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 200 ℃, the roasting time is 60 minutes, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling. The method comprises the steps of carrying out dry self-grinding on waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 500g of waste quartz crucible quartz glass sand into a stirring tank, setting the rotating speed to be 200r/min, carrying out self-grinding for 5min, collecting fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished, sieving and analyzing the fine powder, wherein most of glass sand is still contained on the sieve, and the complete separation of the crystallization layer and fused quartz cannot be realized.

Comparative example 2 the method comprises the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements is shown in table 18 (detected by using an ICP-OES method).

TABLE 18 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	53.64	43.57	2.78	21.36	5.31	0.44	18.42	16.35	99.47
Fused silica	42.37	36.59	1.67	23.75	5.96	0.37	16.77	19.67	99.51

Firstly, placing a waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to 10mm, then, further crushing the waste quartz crucible by a double-roller crusher, and collecting fine powder of a crystallization layer which is peeled and crushed in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm, and taking oversize materials to obtain waste quartz crucible sand fine powder with the particle size of more than 0.83 mm; taking the undersize to obtain waste quartz crucible sand fine powder with the particle size smaller than 0.83 mm.

Performing wet ball milling on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 500g of waste quartz crucible sand into a stirring tank, adding 100g of agate balls, setting the rotating speed to be 230r/min, performing ball milling for 15min, and after the ball milling is finished, stripping and grinding the devitrified layer fine powder in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm, collecting the devitrified layer fine powder 347g.

The fine powder of the crystallization layer which is screened out cannot separate the crystallization layer from the fused quartz.

Comparative example 3 the method comprises the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements is shown in table 19 (detected by using an ICP-OES method).

TABLE 19 impurity element content (ppm) of waste quartz crucible

Composition of the components	Al	Ca	Cu	Fe	K	Li	Mg	Ba	SiO ₂ (％)
										Crystallization layer	54.5	42.21	2.45	25.4	9.34	0.22	19.43	15.67	99.36
Fused silica	41.34	45.65	1.73	24.04	5.61	0.36	17.67	17.95	99.55

Firstly, placing a waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to 15mm, then passing through a double-roller crusher, further crushing, and removing fine powder of a crystallization layer peeled and crushed in the crushing process through a square hole or round hole sieve with the diameter of 0.83mm to obtain waste quartz crucible sand fine powder with the particle size of more than 0.83 mm; taking the undersize to obtain waste quartz crucible sand fine powder with the particle size smaller than 0.83 mm.

Placing the waste quartz crucible sand fine powder with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 200 ℃, the roasting time is 30min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible sand fine powder into cooling water for cooling.

Carrying out dry self-grinding on the waste quartz crucible sand fine powder subjected to high-temperature roasting, putting 500g of waste quartz crucible quartz glass sand into a stirring tank, setting the rotating speed to be 200r/min, carrying out self-grinding for 5min, removing the fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding processes by adopting a square hole or round hole sieve with the diameter of 0.18mm after the self-grinding time is finished, and taking a screen-top substance to obtain 420g of coarse high-purity fused quartz glass sand containing cristobalite; the undersize was taken as 420g of coarse cristobalite sand containing fused silica glass sand.

The screen still contains partial cristobalite sand, the separation of the crystallization layer and the fused quartz can not be realized, and the screen still contains partial cristobalite glass sand, and the separation of the crystallization layer and the cristobalite can not be realized.

Comparative example 4 the method comprises the steps of:

the selected waste quartz crucible is mainly fused quartz, the outer wall of the waste quartz crucible is provided with a crystallization layer, the crystallization layer is mainly cristobalite phase, and the content of main impurity elements is shown in a table 20 (detected by an ICP-OES method).

TABLE 20 impurity element content (ppm) of waste quartz crucible

Firstly, placing a waste quartz crucible in a jaw crusher, crushing most of the waste quartz crucible to 10mm, then, further crushing the waste quartz crucible by a double-roll crusher, and removing fine powder of a crystallization layer which is peeled and crushed in the crushing process by a square hole or round hole sieve with the diameter of 0.83mm to obtain waste quartz crucible glass sand with the particle size of more than 0.83 mm; taking the undersize to obtain waste quartz crucible sand fine powder with the particle size smaller than 0.83 mm.

Placing the waste quartz crucible glass sand with the particle size of more than 0.83mm into a high-temperature roasting kiln for roasting, wherein the roasting temperature is 400 ℃, the roasting time is 10min, rapidly taking out after the roasting is finished, and pouring the waste quartz crucible glass sand into cooling water for cooling.

Performing dry ball milling on the waste quartz crucible glass sand, putting 500g of the waste quartz crucible glass sand into a stirring tank, adding 200g of agate balls, setting the rotating speed to be 200r/min, performing ball milling for 15min, removing fine powder of a crystallization layer peeled and ground in the heating roasting and self-grinding process by adopting a square hole or round hole sieve with the diameter of 0.18mm after the ball milling time is over, and taking the oversize to obtain 347g of coarse high-purity fused quartz glass sand containing cristobalite. The method comprises the steps of carrying out a first treatment on the surface of the The undersize was taken as 420g of coarse cristobalite sand containing fused silica glass sand.

The screen still contains partial cristobalite sand, the separation of the crystallization layer and the fused quartz can not be realized, and the screen still contains partial cristobalite glass sand, and the separation of the crystallization layer and the cristobalite can not be realized. And contains coarse cristobalite high-purity fused quartz glass sand SiO ₂ The purity was reduced to 98.94%.

TABLE 21 list of the main conditions of examples 1-8 and comparative examples 1-4

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Experimental example trial purification process cost calculation

The equipment used in the process of treating the waste quartz crucible is as follows: the amount, the treatment capacity and the power of the horizontal ore dressing fine grinding machine, the ultrasonic cleaner/scrubbing machine, the jaw crusher, the ball mill, the vibrating screen, the plate-and-frame filter press, the high-temperature furnace and the reaction kettle can be referred to the parameters of the equipment commonly used in the current market.

The reagent costs (reference to the commercially available drug information) are as follows:

calculated by treating 1 ton of waste quartz crucible per day (the treatment amount of each step differs depending on the yield of the previous step, and the conversion of Table 45 is carried out):

table 45 uses the medicine and cost conditions

Note that: the purity of the selected medicines is different, and the dosage, price and actual condition of the medicines are in and out to a certain extent.

The energy consumption is as follows:

according to the power references of the equipment, the energy consumption of one operation is about 115-145.2 kW calculated according to 8 hours of daily operation, and the energy consumption of one operation is about 117.875-148.83 yuan calculated according to the price of 1.025 yuan per kilowatt hour. It can be seen that by using the above-described method of the present application for estimation, the waste quartz crucible can be recycled in a very economical and energy-saving manner.

Although the embodiments of the present application have been described above in connection with the above, the present application is not limited to the above-described specific embodiments and fields of application, which are merely illustrative, instructive, and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous forms of the application without departing from the scope of the application as claimed.

Claims

4. The method according to claim 1 to 3, wherein,

5. A method according to any one of claims 1 to 3, wherein the waste quartz crucible is crushed by crushing in step 1) to particles having a particle size of less than 10 mm;

6. The method according to claim 1 to 3, wherein,

7. The method according to claim 1 to 3, wherein,

8. The method according to claim 1 to 3, wherein,

9. The method according to claim 1 to 3, wherein,

10. The method according to claim 1 to 3, wherein,

11. The method according to claim 1 to 3, wherein,

12. The method according to claim 1 to 3, wherein,

13. The method according to claim 1 to 3, wherein,

14. A process according to any one of claims 1 to 3, wherein the pickling is carried out with a nitric acid solution having a concentration of 0.1 to 2mol/L, preferably the ratio of the addition of nitric acid solution to the volume mass of the first undersize is 1 to 6L/Kg, more preferably the stirring speed of the pickling is 200 to 500r/min, and the stirring pickling time is 1 to 3h.

15. The method according to any one of claims 1, 3 to 14, wherein,

16. The method according to any one of claims 2, 3 to 14, wherein,

17. The method according to any one of claims 3 to 14, wherein,

the granularity of the prepared second high-purity fused silica glass sand is less than 0.18mm, and SiO is contained in the second high-purity fused silica glass sand ₂ The content is 98-99.9%, the amorphous content is 95%The content of Ba is lower than 15 mg/kg of high-purity cristobalite sand;

18. A graded cristobalite sand and fused silica glass sand, comprising:

19. Graded cristobalite sand and fused silica glass sand according to claim 18, which are prepared by the method of any one of claims 1, 3 to 14.

20. A graded cristobalite sand and fused silica glass sand, comprising:

21. Graded cristobalite sand and fused silica glass sand according to claim 20, which are prepared by the method of any one of claims 2, 3 to 14.

22. A graded cristobalite sand and fused silica glass sand, comprising:

23. Graded cristobalite sand and fused silica glass sand according to claim 22, which are prepared by the method of any one of claims 3 to 14.

24. Use of the graded cristobalite sand and fused silica glass sand according to any one of claims 18 to 23, wherein the first and second high purity cristobalite sand are used as metallurgical raw materials, first party quartz sand, first high purity fused silica glass sand and second high purity fused silica glass sand metallurgical additives, for the production of silicon compounds, as blanks for porcelain and refractory materials, the first and first party quartz sand being used as a filler for construction machinery.