High-purity quartz sand and short-process heat treatment processing technology thereof

Abstract

The invention provides high-purity quartz sand and a short-process heat treatment processing technology thereof, and the technology comprises the following steps: S1, crushing to make sand to obtain a high-purity quartz sand precursor with qualified particle size; s2, performing magnetic separation and flotation to obtain high-purity quartz sand; s3, primary acid pickling is conducted, specifically, the high-purity quartz sand rough sand and acid liquor are mixed and subjected to acid pickling, and high-purity quartz sand fine sand is obtained; s4, atmosphere calcination and water quenching: putting the high-purity quartz fine sand into a container, introducing a special atmosphere, carrying out high-temperature calcination, introducing nitrogen for purging after calcination is completed, then taking out a calcined product, and carrying out rapid water quenching to obtain high-purity quartz cooked sand; s5, secondary acid pickling: performing mixed acid pickling on the high-purity quartz sand cooked sand and acid liquor to obtain secondary acid-pickled sand; and S6, sand drying and baking, wherein the secondary acid pickling sand is subjected to high-temperature baking, and a high-purity quartz sand product is obtained. The method has the beneficial effects that the technological process is shortened, the production efficiency is improved, the production cost is saved, and the product purity and stability can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity quartz separation. Specifically, it relates to a high-purity quartz sand and its short-process heat treatment processing technology. Background Art

[0002] High-purity quartz is widely used in strategic emerging industries such as semiconductor chips and solar photovoltaics, and is an indispensable and irreplaceable key basic material. In the semiconductor industry, high-purity quartz sand is one of the key raw materials for manufacturing chips, and its high purity and stability can ensure the accuracy and quality of chip production. For example, high-purity quartz sand is used to manufacture quartz crucibles, which are important containers for producing polysilicon and monocrystalline silicon, and silicon materials are the basic raw materials for semiconductor integrated circuits. In the photovoltaic industry, high-purity quartz is the key raw material for manufacturing solar panels, and its excellent high-temperature resistance and light transmission performance help to improve the conversion efficiency of solar cells, thus promoting the development of the photovoltaic industry. In short, due to its unique properties, high-purity quartz sand plays an irreplaceable role in the semiconductor and photovoltaic industries.

[0003] The processing technology of high-purity quartz sand generally includes crushing, calcination water quenching, sand making, magnetic separation, flotation, pickling, chlorination, etc. Among them, calcination water quenching and high-temperature chlorination are two crucial heat treatment processes, which each undertake different purification tasks and have a significant impact on the improvement of the final product purity. The calcination water quenching process mainly plays a pretreatment role. By heating the quartz ore to a high temperature and then quickly quenching it with water, cracks are generated inside the quartz particles using the principle of thermal expansion and contraction, effectively reducing the hardness of the quartz and exposing the impurities wrapped inside the quartz, which helps to deeply remove impurities. The high-temperature chlorination process is mainly to further improve the purity of the quartz sand. Under the action of high temperature, using chlorinating agents such as chlorine or hydrogen chloride to react with the impurity elements in the quartz sand to generate gaseous chlorides and discharge them with the gas flow, so as to achieve the purpose of deep purification.

[0004] However, these two heat treatment processes of calcination water quenching and high-temperature chlorination bring relatively high energy consumption. Driven by the price competition of high-purity quartz sand, it is urgent to develop a short-process heat treatment processing technology for high-purity quartz sand to reduce production costs and improve market competitiveness. Summary of the Invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies existing in the prior art. For example, one of the purposes of the present invention is to provide a high-purity quartz sand and its short-process heat treatment processing technology, which shortens the process flow, improves production efficiency, and can improve the product purity and stability.

[0006] To achieve the above purpose, the present invention provides a short-process heat treatment processing technology for high-purity quartz sand, including the following steps:

[0007] S1. Crushing and sand making

[0008] Crush and make sand from high-purity quartz raw ore to obtain a high-purity quartz sand precursor with a qualified particle size;

[0009] S2. Magnetic separation and flotation

[0010] Perform magnetic separation and flotation on the high-purity quartz sand precursor to obtain high-purity quartz sand rough sand;

[0011] S3. First pickling

[0012] Mix and pickle the high-purity quartz sand rough sand with acid solution to obtain high-purity quartz sand fine sand;

[0013] S4. Calcination in atmosphere and water quenching

[0014] Place the high-purity quartz sand fine sand in a container, introduce a special atmosphere, perform high-temperature calcination, purge with nitrogen after calcination is completed, then take out the calcination product and quickly water quench it to obtain high-purity quartz sand mature sand;

[0015] S5. Second pickling

[0016] Mix and pickle the high-purity quartz sand mature sand with acid solution to obtain second pickled sand;

[0017] S6. Drying and roasting sand

[0018] Dry and roast the second pickled sand to obtain high-purity quartz sand products.

[0019] In a preferred embodiment of this solution, in step S1, the crushing and sand making adopts any one of dry method or wet method for sand making.

[0020] In a preferred embodiment of this solution, in step S1, the qualified particle size is 60 - 200 mesh.

[0021] In a preferred embodiment of this solution, in step S2, the magnetic separation is one of continuous magnetic separation or intermittent magnetic separation; and / or the flotation is one of continuous flotation or intermittent flotation.

[0022] In a preferred embodiment of this solution, in step S2, the SiO2 content in the high-purity quartz sand rough sand is not less than 99.9%.

[0023] In a preferred embodiment of this solution, the acid solutions in steps S3 and S4 are both mixed acid solutions of hydrochloric acid and hydrofluoric acid; in the mixed acid solution, the weight ratio of hydrochloric acid to hydrofluoric acid is 5:5 - 9:1, and the concentration of the mixed acid solution is 10 - 30%.

[0024] In a preferred embodiment of this solution, in step S3, the solid-to-liquid ratio of the pickling solution for the first pickling is 2:1 to 5:1, the pickling temperature is 80 to 100 °C, and the pickling time is 12 to 48 h.

[0025] In a preferred embodiment of this solution, in step S5, the solid-to-liquid ratio of the pickling solution for the second pickling is 2:1 to 5:1, the pickling temperature is 80 to 100 °C, and the pickling time is 6 to 12 h.

[0026] In a preferred embodiment of this solution, in step S3, the acid solution is the waste acid from the second pickling. The acid solution in step S3 can use fresh acid or the waste acid after the second pickling in step S5 to achieve efficient resource utilization.

[0027] In a preferred embodiment of this solution, in step S4, the special atmosphere is any one of Cl2 and HCl gases. Preferably HCl gas.

[0028] In a preferred embodiment of this solution, in step S4, the calcination temperature for the high-temperature calcination is 1100 to 1400 °C, and the calcination time is 20 to 60 min.

[0029] A high-purity quartz sand is obtained by the above short-process heat treatment processing technology, and the purity of the high-purity quartz sand is greater than 99.99%.

[0030] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0031] (1) A high-purity quartz sand and its short-process heat treatment processing technology proposed in this solution shorten the process flow, improve production efficiency, save production costs, and at the same time, through the final pickling check, the product purity and stability can be further improved;

[0032] (2) In the process of this solution, the first pickling can use the waste liquid from the second pickling, realizing the recycling of waste acid and thus achieving efficient resource utilization. Description of the Drawings

[0033] Through the following description with reference to the drawings, the above and other objects and / or features of the present invention will become clearer, where:

[0034] Figure 1 Shows a schematic flow diagram of an exemplary embodiment of a high-purity quartz sand and its short-process heat treatment processing technology of the present invention. Detailed Embodiments

[0035] In the following, a high-purity quartz sand and its short-process heat treatment processing technology of the present invention will be described in detail in conjunction with exemplary embodiments.

[0036] Exemplary Embodiment 1

[0037] Reference Figure 1 As shown, a short-process heat treatment processing technology of high-purity quartz sand, its characteristic steps include:

[0038] S1. Crushing and sand making: Crushing and sand making the high-purity quartz raw ore to obtain a high-purity quartz sand precursor with a qualified particle size. This step is mainly to provide raw materials with a qualified particle size for the next separation and purification.

[0039] S2. Magnetic separation and flotation: Conducting magnetic separation and flotation on the high-purity quartz sand precursor to obtain crude high-purity quartz sand. This step is mainly to thoroughly separate impurity minerals such as feldspar, mica, magnetite, and hematite as much as possible, providing qualified raw materials for the next chemical purification.

[0040] S3. Primary pickling: Mixing and pickling the crude high-purity quartz sand with acid solution to obtain high-purity quartz sand concentrate. This step is mainly to dissolve and remove the associated impurity minerals and shallow impurity inclusions as much as possible, reducing the influence of impurity minerals on subsequent purification, and increasing the specific surface area of the quartz sand by increasing the degree of dissolution of the quartz sand, providing active sites for the next atmosphere calcination and water quenching.

[0041] S4. Atmosphere calcination and water quenching: Placing the high-purity quartz sand concentrate in a container, introducing a special atmosphere, and performing high-temperature calcination. When the reaction time ends, purging with nitrogen, taking out the calcination product and quickly quenching it with water to obtain high-purity quartz sand mature sand. This step is mainly to remove impurity elements such as Al, K, Na, and Ti by the action of high-temperature chlorination to form volatile chlorides. Water quenching mainly uses the principle of thermal expansion and contraction to further generate cracks inside the quartz particles, exposing the impurities that are not reacted and wrapped inside the quartz. At the same time, it can cause the gas-liquid inclusions to burst, creating convenient conditions for secondary pickling.

[0042] S5. Secondary pickling: Mixing and pickling the high-purity quartz sand mature sand with acid solution to obtain high-purity quartz sand products. This step is mainly to remove two aspects of impurity elements. One is the chlorides that are not completely volatilized and adhere to the surface of the quartz sand particles, and the other is the impurity minerals that are exposed after bursting due to water quenching.

[0043] S6. Drying and roasting: Drying and roasting the secondary pickled sand at a temperature of 800 - 1100 °C (such as 850 °C, 900 °C, 1000 °C, 1050 °C) to obtain high-purity quartz sand products.

[0044] Further, in this exemplary embodiment, in step S1, sand making can adopt either dry or wet sand making method, and the qualified particle size is controlled within 60 - 200 mesh. Dry sand making has the advantages of high flexibility and convenient material turnover, etc., but at the same time has disadvantages such as large dust and difficulty in cleaning residual impurities in equipment, which is not conducive to replacing materials; wet sand making has the advantages of small dust and uniform particles, etc., but there are problems such as relatively more material loss and the need to rely on pumps for material turnover, which is prone to blockage. It is necessary to reasonably select the sand making method according to the material properties and process requirements.

[0045] In this exemplary embodiment, in step S2, magnetic separation and flotation can each adopt either continuous or batch type. The SiO2 content in the raw quartz sand of high-purity quartz sand is not less than 99.9%. Continuous flotation has the advantages of large processing capacity and low operation intensity, but the production indexes are prone to fluctuate; batch flotation has the advantages of stable index control and flexible operation, etc., but the labor intensity is high and it is not conducive to intelligent control.

[0046] Further, in this exemplary embodiment, in step S3, the acid solution is either the waste acid or the new acid from secondary pickling. The acid solution is a mixed acid solution with a weight ratio of hydrochloric acid to hydrofluoric acid of 5:5 - 9:1 (such as 6:5, 7:3, 8:1, etc.), the mixed acid concentration of the mixed acid solution is 10 - 30% (such as 15%, 20%, 25%, etc.), the liquid-solid ratio of pickling is 2:1 - 5:1 (such as 3:1, 5:2, 4:1, etc.), the pickling temperature is 80 - 100 °C (such as 85 °C, 90 °C, 95 °C, etc.), and the pickling time is 12 - 48 h (such as 15 h, 30 h, 45 h, etc.).

[0047] Further, in this exemplary embodiment, in step S4, the special atmosphere is either Cl2 or HCl gas, preferably HCl gas, with a dosage of 20 - 30 kg / t (such as 22 kg / t, 25 kg / t, 28 kg / t, etc.). HCl gas has the characteristic of relatively low toxicity, and the production operation is relatively safe. HCl gas reacts chemically with the exposed impurities under high-temperature conditions to generate gaseous chlorides and escape, thereby removing elements such as Na, K, and Fe.

[0048] Further, in this exemplary embodiment, in step S4, the temperature of the atmosphere calcination is 1100 - 1400 °C (such as 1150 °C, 1200 °C, 1300 °C, etc.), and the calcination time is 20 - 60 min (such as 30 min, 40 min, 50 min, etc.).

[0049] Further, in this exemplary embodiment, in step S5, the acid solution ratio, concentration, liquid-solid ratio, and temperature are the same as those in step S3, and the pickling time is 6 - 12 h (such as 7 h, 9 h, 11 h, etc.). To save the pickling cost, the acid solution in step S5 can also be returned to S3 for reuse because the purity of the quartz sand entering step S5 is relatively high, and after pickling, the impurity content in the acid solution is also relatively low. Therefore, it can be returned to S3 to treat the quartz sand with a relatively high impurity content. Additionally, this pickling can not only further deeply clean the newly exposed impurity elements after cracking but also wash away the chloride that has not completely volatilized and adhered to the surface of the quartz particles.

[0050] The basic principle by which the present invention can achieve deep purification of high-purity quartz sand and shorten the heat treatment process flow is as follows:

[0051] By adopting the process of calcining in an atmosphere and quenching with water, the synergistic effect of physical and chemical processes is achieved. During the atmosphere calcination, the high temperature causes the quartz lattice to expand, the inclusions to burst, and at the same time, certain micro-channels will be formed. At this time, in the high-temperature environment, it is more conducive for HCl or Cl2 gas to penetrate into the quartz interior through the micro-channels and react with the exposed impurities. The reaction equation is MO + 2HCl → MCl2 + H2O (M is an impurity element), and the low-boiling-point chloride is generated and volatilized. Then, during the water quenching process, the quartz particles can be further cracked to generate more micro-cracks, which is convenient for subsequent pickling operations to remove. By adopting the technical process of the present invention, the traditional multi-stage process flows such as calcining and quenching with water and chlorination roasting are combined, shortening the process flow, improving the production efficiency, and saving the production cost.

[0052] To better understand the above exemplary embodiment of the present invention, it is further described below with examples.

[0053] Example 1

[0054] Select a high-purity quartz raw material from a certain granite in Henan. After being crushed by a jaw crusher and a pair-roll crusher, a rod mill is used for grinding. After screening by a standard sieve, 60 - 200 mesh coarse sand is obtained; the coarse sand is magnetically separated 3 times in a high-gradient magnetic separator with a magnetic field intensity of 1.6 T. After magnetic separation, flotation is carried out, and the SiO2 purity in the flotation concentrate is 99.962%; under the conditions of a weight ratio of hydrochloric acid to hydrofluoric acid of 9:1, a mixed acid concentration of 10%, a liquid-solid ratio of 2:1, a pickling temperature of 80 °C, and a pickling time of 12 h, primary pickled sand is obtained; calcining and water quenching are carried out under the conditions of an HCl atmosphere, a calcining temperature of 1100 °C, a calcining time of 20 min, and an HCl gas consumption of 20 kg / t; secondary pickling is carried out under the conditions consistent with those of the primary pickling; after being washed to neutral and dehydrated, roasting is carried out at 800 °C to obtain a high-purity quartz sand product. The test results of this high-purity quartz sand product are shown in Table 1.

[0055] Table 1 Chemical analysis results of the high-purity quartz sand product in Example 1

[0056] Al B Ca Cr Cu Fe K Li Mg 14.54 0.10 1.41 <0.01 0.05 1.27 1.72 0.11 0.28 Mn Na Ni P Ti Zn Total impurities Purity / % 0.10 1.06 <0.01 1.44 1.90 0.12 25.11 99.9976

[0057] Note: The unit of each element content in the table is ppm.

[0058] Example 2

[0059] Select a high-purity quartz raw material from a certain granite in Henan. After being crushed by a jaw crusher and a pair-roll crusher, a rod mill is used for grinding. After screening by a standard sieve, 60-200 mesh coarse sand is obtained; the coarse sand is magnetically separated 3 times in a high-gradient magnetic separator with a magnetic field strength of 1.6 T, and then flotation is carried out after magnetic separation. The SiO2 purity in the flotation concentrate is 99.931%; under the conditions of a weight ratio of hydrochloric acid to hydrofluoric acid of 5:5, a mixed acid concentration of 30%, a liquid-solid ratio of 5:1, an acid pickling temperature of 100 °C, and an acid pickling time of 48 h, primary acid pickled sand is obtained; calcination and water quenching are carried out under the conditions of an HCl atmosphere, a calcination temperature of 1400 °C, a calcination time of 60 min, and an HCl gas consumption of 30 kg / t; secondary acid pickling is carried out under the same conditions as the primary acid pickling; after being washed to neutral and dehydrated, roasting is carried out at 1100 °C to obtain a high-purity quartz sand product. The chemical analysis results of this high-purity quartz sand product are shown in Table 2.

[0060] Table 2 Chemical analysis results of the high-purity quartz sand product in Example 2

[0061] Al B Ca Cr Cu Fe K Li Mg 10.55 0.12 0.77 0.05 <0.01 0.44 0.62 0.03 0.19 Mn Na Ni P Ti Zn Total impurities Purity / % <0.01 0.35 0.02 0.35 1.02 0.05 14.56 99.9985

[0062] Note: The unit of each element content in the table is ppm.

[0063] Example 3

[0064] Select a high-purity quartz raw material from a certain granite in Henan. After being crushed by a jaw crusher and a pair-roll crusher, a rod mill is used for grinding. After screening by a standard sieve, 60-200 mesh coarse sand is obtained; the coarse sand is magnetically separated 3 times in a high-gradient magnetic separator with a magnetic field strength of 1.6 T, and then flotation is carried out after magnetic separation. The SiO2 purity in the flotation concentrate is 99.942%; under the conditions of a weight ratio of hydrochloric acid to hydrofluoric acid of 7:3, a mixed acid concentration of 15%, a liquid-solid ratio of 4:1, an acid pickling temperature of 90 °C, and an acid pickling time of 24 h, primary acid pickled sand is obtained; calcination and water quenching are carried out under the conditions of an HCl atmosphere, a calcination temperature of 1200 °C, a calcination time of 40 min, and an HCl gas consumption of 25 kg / t; secondary acid pickling is carried out under the same conditions as the primary acid pickling; after being washed to neutral and dehydrated, roasting is carried out at 1000 °C to obtain a high-purity quartz sand product. The chemical analysis results of this product are shown in Table 3.

[0065] Table 3 Chemical analysis results of the high-purity quartz sand product in Example 3

[0066] Al B Ca Cr Cu Fe K Li Mg 11.53 0.05 1.07 0.02 <0.01 0.85 1.26 0.03 0.04 Mn Na Ni P Ti Zn Total impurities Purity / % 0.05 1.10 <0.01 0.82 1.12 0.05 18.70 99.9981

[0067] Note: The unit of the content of each element in the table is ppm.

[0068] Example 4

[0069] Select a high-purity quartz raw material from a certain white granite in Henan. After crushing by a jaw crusher and a pair-roll crusher, a rod mill is selected for grinding. After screening by a standard sieve, 60-200 mesh coarse sand is obtained; the coarse sand is magnetically separated 3 times in a high-gradient magnetic separator with a magnetic field intensity of 1.6 T. After magnetic separation, flotation is carried out, and the purity of SiO2 in the flotation concentrate is 99.942%; under the conditions that the weight ratio of hydrochloric acid to hydrofluoric acid is 7:3, the concentration of the mixed acid is 15%, the liquid-solid ratio is 4:1, the pickling temperature is 90 °C, and the pickling time is 24 h, primary pickled sand is obtained. It should be noted here that the acid used this time is the waste acid from the secondary pickled sand; calcination and water quenching are carried out under the conditions of HCl atmosphere, a calcination temperature of 1200 °C, a calcination time of 40 min, and an HCl dosage of 25 kg / t; secondary pickling is carried out under the conditions consistent with the primary pickling conditions; after washing to neutral and dehydrating, roasting is carried out at 1000 °C to obtain a high-purity quartz sand product. After the waste acid is reused, under the same test parameters, the impurity elements such as Al, Ca, K, Na, P, and Ti in the product all increase, but a 4N8 grade high-purity quartz sand can still be obtained. The test results of the product are shown in Table 4.

[0070] Table 4 Test Results of the High-Purity Quartz Sand Product in Example 4

[0071] Al B Ca Cr Cu Fe K Li Mg 11.83 0.11 1.17 0.02 <0.01 0.82 1.46 0.07 0.14 Mn Na Ni P Ti Zn Total impurities Purity / % 0.05 1.30 <0.01 0.88 1.52 0.05 20.03 99.9980

[0072] Note: The unit of the content of each element in the table is ppm.

[0073] Although the present invention has been described above in conjunction with the exemplary embodiments and the accompanying drawings, those of ordinary skill in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A short-process heat treatment processing technology for high-purity quartz sand, characterized in that, It includes the following steps: S1. Crushing and sand making Crush the high-purity quartz raw ore into sand to obtain the high-purity quartz sand precursor with qualified particle size; S2. Magnetic separation and flotation Perform magnetic separation and flotation on the high-purity quartz sand precursor to obtain the crude high-purity quartz sand; S3. Primary pickling Mix and pickle the crude high-purity quartz sand with the acid solution to obtain the refined high-purity quartz sand; S4. Calcination in atmosphere and water quenching Place the refined high-purity quartz sand in a container, introduce a special atmosphere, and conduct high-temperature calcination. After the calcination is completed, introduce nitrogen for purging, then take out the high-purity quartz sand and quickly quench it with water to obtain the mature high-purity quartz sand; S5. Secondary pickling Mix and pickle the mature high-purity quartz sand with the acid solution to obtain the sand after secondary pickling; S6. Drying and roasting the sand Dry and roast the sand after secondary pickling to obtain the high-purity quartz sand product.

2. The short-process heat treatment processing technology of a high-purity quartz sand according to claim 1, characterized in that: In the step S1, the qualified particle size is 60 - 200 mesh.

3. A short-process heat treatment processing technology for high-purity quartz sand according to claim 1, characterized in that: In the step S2, the SiO2 content in the crude high-purity quartz sand is not less than 99.9%.

4. A short-process heat treatment processing technology for high-purity quartz sand according to claim 1, characterized in that: The acid solutions in the steps S3 and S4 are both mixed acid solutions of hydrochloric acid and hydrofluoric acid; In the mixed acid solution, the weight ratio of hydrochloric acid to hydrofluoric acid is 5:5 - 9:1, and the concentration of the mixed acid solution is 10 - 30%.

5. The short-process heat treatment processing technology of high-purity quartz sand according to claim 4, characterized in that: In the step S3, the solid-to-liquid ratio of the acid pickling solution for primary pickling is 2:1 - 5:1, the pickling temperature is 80 - 100 °C, and the pickling time is 12 - 48 h.

6. The short-process heat treatment processing technology of a high-purity quartz sand according to claim 4, characterized in that: In the step S5, the solid-to-liquid ratio of the acid pickling solution for secondary pickling is 2:1 - 5:1, the pickling temperature is 80 - 100 °C, and the pickling time is 6 - 12 h.

7. A short-process heat treatment processing technology for high-purity quartz sand according to claim 4, characterized in that: In the step S3, the acid solution is the waste acid from secondary pickling.

8. The short-process heat treatment processing technology of a high-purity quartz sand according to claim 1, characterized in that: In the step S4, the special atmosphere is any one of Cl2 and HCl gases.

9. A short-process heat treatment processing technology for high-purity quartz sand according to claim 1, characterized in that: In the step S4, the calcination temperature for high-temperature calcination is 1100 - 1400 °C, and the calcination time is 20 - 60 min.

10. A high-purity quartz sand, characterized in that, The high-purity quartz sand is obtained by the short-process heat treatment processing technology described in any one of claims 1 - 9, and the purity of the high-purity quartz sand is greater than 99.99%.

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