Purification method for removing quartz inclusion

Abstract

The invention discloses a purification method for removing quartz inclusion, which comprises the following steps: calcining a quartz sand raw material at high temperature for a certain time, then taking out and quickly putting into cold water for cold quenching; dehydrating quartz sand, feeding into a microwave reactor, heating to a set temperature, and keeping for a period of time; after the reaction is finished, cleaning the quartz sand with ultrapure water; filling the quartz sand into a high-temperature and high-pressure reactor, introducing supercritical carbon dioxide and hydrogen fluoride mixed gas, and keeping the temperature and the pressure for a period of time; and after the reaction is finished, discharging gas to obtain the high-purity quartz. Through two-stage heat treatment, a channel between gas-liquid inclusions in quartz particles and the outside can be efficiently opened, and meanwhile, the supercritical method ensures that impurities in the inclusions can be effectively dissolved out; the treatment time is short, the required temperature is low, the acid consumption is less than 10%, and the method has the advantages of high efficiency and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quartz processing and relates to a processing method of ultra-high-purity quartz. BACKGROUND

[0002] Quartz is an important raw material in industrial production, and high-purity quartz is an irreplaceable product in strategic emerging fields such as semiconductors, photovoltaics, chips, communications and aerospace. With the rapid development of China's high-tech industries such as solar energy, the demand and quality requirements for quartz products are continuously improving. At present, the domestic quartz processing technology has not made a significant breakthrough in the removal of inclusion impurities, which limits the improvement of product quality, resulting in that most of the high-purity quartz products rely on imports, which seriously threatens the safety of China's strategic emerging industries.

[0003] In the prior art, the limitation of quartz purification lies in the gas-liquid inclusion impurities in quartz particles. At present, the process of acid leaching and chlorination roasting is mainly used for treatment, which usually has large acid dosage (> 30%), high temperature (1200℃), long time (> 16h), heavy environmental pollution, high production cost, and limited purification efficiency.

[0004] Therefore, it is of great significance to actively explore the quartz inclusion removal technology and break through the ultra-high-purity quartz processing technology. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the application is to provide a purification method for removing quartz inclusions.

[0006] To achieve the above purpose, a purification method for removing quartz inclusions, characterized in that it comprises the following steps:

[0007] (1) One-stage heat treatment: calcine the quartz sand raw material at high temperature for a certain time, and then take it out and quickly put it into cold water for quenching;

[0008] (2) Two-stage heat treatment: after the quartz sand in step (1) is dehydrated, it is sent into a microwave reactor, heated to a set temperature and kept for a period of time; after the reaction is completed, the quartz sand is washed with ultrapure water;

[0009] (3) Leaching: the quartz sand in step (2) is loaded into a high-temperature and high-pressure reactor, and a mixed gas of supercritical carbon dioxide and hydrogen fluoride is introduced, and the temperature and pressure are kept for a period of time; after the reaction is completed, the gas is discharged, and a high-purity quartz is obtained.

[0010] Preferably, in step (1), the SiO2 in the quartz sand raw material is ≥ 99.9%; the calcination temperature is 800-1000℃, and the time is 1-3h.

[0011] Preferably, in step (2), the temperature is 1000-1200℃, and the time is 1-2h.

[0012] Preferably, in step (3), the temperature is 40-100℃, the pressure is 75-100atm, and the time is 30-120min.

[0013] The present application pre-treats the quartz sand raw material through two-stage heat treatment. The first stage of heat treatment causes the quartz crystal form to change, improving its brittleness and weakening the strength of the quartz particles. The second stage of heat treatment uses microwaves to heat the inclusions. Under the action of thermal expansion, the force is transmitted from the inside of the inclusions to the outside, thereby causing cracks to occur and forming openings that are connected to the outside. Finally, the high diffusivity and solubility of supercritical gas enable it to enter the interior of the inclusions through very small gaps and dissolve the impurities such as salts therein, thereby achieving the removal of the inclusions.

[0014] Through the use of the above technical solution, the present application has the following beneficial effects:

[0015] (1) The two-stage heat treatment can efficiently open the channels of the gas-liquid inclusions in the quartz particles to the outside, and the supercritical method ensures that the impurities in the inclusions can be effectively dissolved out.

[0016] (2) The technical solution of the present application has the advantages of short processing time, low required temperature, and acid usage <10%, high efficiency, and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The purification process flow chart for removing inclusions.

[0018] Figure 2 The schematic diagram of the inclusion impurity removal process.

[0019] Figure 3 SEM photo of quartz particles. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the specific content of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0021] Embodiment 1

[0022] The present embodiment provides a purification method for removing quartz inclusions, comprising the following steps:

[0023] (1) One-stage heat treatment: SiO2 content 99.98% quartz sand raw material is calcined at 900°C for 2h, then quickly taken out and put into cold water for quenching;

[0024] (2) Two-stage heat treatment: After step (1) of quartz sand dehydration, it is sent into a microwave reactor, heated to 1000°C and kept for 1h; after the reaction is completed, the quartz sand is washed with ultrapure water;

[0025] (3) Leaching: The quartz sand in step (2) is loaded into a high-temperature and high-pressure reactor, and a mixed gas of supercritical carbon dioxide and hydrogen fluoride is introduced, kept at 50°C and 80atm pressure for 60min; after the reaction is completed, the gas is discharged, and a high-purity quartz is obtained.

[0026] Example 2

[0027] The embodiment provides a purification method for removing quartz inclusions, comprising the following steps:

[0028] (1) One-stage heat treatment: SiO2 content 99.98% quartz sand raw material is calcined at 900°C for 2h, then quickly taken out and put into cold water for quenching;

[0029] (2) Two-stage heat treatment: After step (1) of quartz sand dehydration, it is sent into a microwave reactor, heated to 1000°C and kept for 2h; after the reaction is completed, the quartz sand is washed with ultrapure water;

[0030] (3) Leaching: The quartz sand in step (2) is loaded into a high-temperature and high-pressure reactor, and a mixed gas of supercritical carbon dioxide and hydrogen fluoride is introduced, kept at 50°C and 80atm pressure for 45min; after the reaction is completed, the gas is discharged, and a high-purity quartz is obtained.

[0031] Example 3

[0032] The embodiment provides a purification method for removing quartz inclusions, comprising the following steps:

[0033] (1) One-stage heat treatment: SiO2 content 99.96% quartz sand raw material is calcined at 1000°C for 1h, then quickly taken out and put into cold water for quenching;

[0034] (2) Two-stage heat treatment: After step (1) of quartz sand dehydration, it is sent into a microwave reactor, heated to 1100°C and kept for 1h; after the reaction is completed, the quartz sand is washed with ultrapure water;

[0035] (3) Leaching: The quartz sand in step (2) is loaded into a high-temperature and high-pressure reactor, and a mixed gas of supercritical carbon dioxide and hydrogen fluoride is introduced, kept at 50°C and 80atm pressure for 60min; after the reaction is completed, the gas is discharged, and a high-purity quartz is obtained.

[0036] Example 4

[0037] The present example provides a purification method for removing quartz inclusions, comprising the following steps:

[0038] (1) One-stage heat treatment: SiO2 content 99.99% quartz sand raw material is calcined at 900°C for 2h, then quickly taken out and put into cold water for quenching;

[0039] (2) Two-stage heat treatment: the quartz sand of step (1) is dehydrated and then sent into a microwave reactor, heated to 1000°C and kept for 1h; after the reaction is completed, the quartz sand is washed with ultrapure water;

[0040] (3) Leaching: the quartz sand in step (2) is loaded into a high-temperature and high-pressure reactor, and a mixture of supercritical carbon dioxide and hydrogen fluoride gas is introduced, keeping 50°C and 80atm pressure for 60min; after the reaction is completed, the gas is discharged, and a high-purity quartz is obtained.

[0041] Comparative Example 1

[0042] The difference between the present comparative example 1 and example 1 is only that step (2) is absent, and the others are the same.

[0043] Comparative Example 2

[0044] The raw material of the present comparative example is the same as that of example 1, and the following process is used for purification: the quartz sand raw material is added with 30% mixed acid and reacted at 70°C for 16h, washed with ultrapure water; after dehydration, it is baked at 1000°C, and then hydrogen chloride is introduced and baked at 1200°C to obtain a high-purity quartz product.

[0045] The high-purity quartz indexes of examples 1-4 and comparative examples 1-2 above are tested, and the test results are shown in Table 1.

[0046] Table 1 Test results

[0047]

[0048] As can be seen from examples 1-4, the impurity content of the quartz can be significantly reduced by using the technical solution of the present application, and a high-purity quartz product is obtained.

[0049] As can be seen from example 1 and comparative example 1, the impurity content of the purified product is significantly increased due to the absence of step (2) microwave heat treatment.

[0050] As can be seen from examples 1, 2 and comparative example 2, the impurity content of the product purified by the present technical solution is lower than that of the existing process, and the effect is better than that of the existing process.

[0051] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A purification method for removing quartz inclusions, characterized in that: The preparation method comprises the following steps: (1) One-stage heat treatment: calcining the quartz sand raw material at high temperature for a certain period of time, then taking it out and quickly immersing it in cold water for cold quenching; (2) Second stage heat treatment: the quartz sand from step (1) is dehydrated and then fed into a microwave reactor, heated to a set temperature and maintained for a period of time; after the reaction is completed, the quartz sand is washed with ultrapure water; (3) Leaching: The quartz sand in step (2) is placed in a high-temperature and high-pressure reactor, a mixture of supercritical carbon dioxide and hydrogen fluoride is introduced, and the temperature and pressure are maintained for a period of time; after the reaction is completed, the gas is discharged to obtain a high-purity quartz.

2. The purification method according to claim 1, wherein In step (1), SiO2 in the quartz sand raw material is ≥99.9%; the calcination temperature is 800-1000°C, and the calcination time is 1-3h.

3. The purification method according to claim 1, wherein In step (2), the set temperature is 1000-1200° C., and the time is 1-2 hours.

4. The purification method according to claim 1, wherein In step (3), the temperature is 40-100° C., the pressure is 75-100 atm, and the time is 30-120 min.

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