Screening method of granite pegmatite ore source for high-purity quartz sand and application of screening method

Abstract

The invention provides a screening method of granite pegmatite ore resources for high-purity quartz sand and application of the screening method, and relates to the technical field of preparation of 4N8-grade high-purity quartz sand. Systematic analysis is conducted on the granite pegmatite ore resources according to a purified product test result and microscopic morphology observation, whether the ore resources have the potential of purifying the high-purity quartz sand or not is judged, and whether the ore resources have the potential of purifying the high-purity quartz sand or not is judged. Whether the granite pegmatite ore source can be used as a potential raw material for preparing 4N8-grade high-purity quartz sand or not can be effectively screened out. According to the method, purification and observation are carried out synchronously and supplement each other, and the quartz ore and the embedded minerals and fluid inclusion in the quartz sand are observed and identified, so that the technical effects of efficiently evaluating the feasibility of preparing the 4N8-grade high-purity quartz sand from the granite pegmatite ore source on the whole and reducing time and other cost investments are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of 4N8 grade high-purity quartz sand, in particular to a method for screening a granite pegmatite source for high-purity quartz sand and application thereof. Background Art

[0002] For the efficient purification and comprehensive evaluation of granite pegmatite, the common purification process in the industry includes raw material pretreatment, physical separation, chemical purification, thermal treatment and fine separation, combined with chemical analysis (such as ICP-OES and XRF), physical property testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and other analytical methods to ensure that the final product meets the industry standards for high-purity silicon materials.

[0003] A Chinese invention patent with authorization publication number CN114804129B discloses a method for purifying quartz sand by completing steps such as scrubbing, flotation, cleaning, pickling, and acid washing in a single reactor, thereby avoiding secondary contamination caused by multiple purification processes during material transportation. However, while this method reduces the number of quartz sand material transfers, it also reduces the material output rate.

[0004] Chinese invention patent application publication number CN118183764A discloses a method for efficiently removing iron and impurities from the mineral surface through conventional magnetic separation, flotation, microwave acid leaching, and microwave calcination explosion under the action of ultrasound, removing impurities from the cleavage gaps between particles, and simultaneously utilizing shock waves or collision and friction between particles to increase the contact area of the reaction, thereby improving the acid leaching and impurity removal effect. After explosion pickling, high-purity quartz sand is purified. However, this method is not suitable for actual production.

[0005] In short, the high-purity quartz sand products purified in the existing technology must be put into actual use before their feasibility can be evaluated, which significantly increases the investment of resources such as time and cost; therefore, the industry urgently needs a method that can efficiently evaluate the feasibility of preparing 4N8 grade high-purity quartz sand from a holistic perspective, thereby reducing the investment of time and other costs.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] One of the purposes of the present invention is to provide a method for screening granite pegmatite sources for high-purity quartz sand, which can effectively evaluate the feasibility of preparing 4N8 grade high-purity quartz sand from granite pegmatite sources as a whole, thereby reducing time and other cost investment.

[0008] The second object of the present invention is to provide an application of a method for screening granite pegmatite sources for high-purity quartz sand, which is beneficial to improving the purity of quartz sand to meet the demand for high-purity silicon materials in the electronics, optics and chemical industries.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] In a first aspect, a method for screening a granite pegmatite source for high-purity quartz sand comprises the following steps:

[0011] Performing rock and mineral identification on a granite pegmatite ore source, sequentially performing magnetic separation and flotation on quartz sand prepared from the granite pegmatite ore source to obtain flotation-extracted quartz sand, performing microscopic morphology observation and impurity content detection on the flotation-extracted quartz sand, performing acid leaching on the flotation-extracted quartz sand to obtain acid-leached quartz sand, and performing microscopic morphology observation and impurity content detection on the acid-leached quartz sand;

[0012] The granite pegmatite ore source, as the raw material of 4N8 grade high-purity quartz sand, meets the following conditions:

[0013] When the number of embedded mineral types in the rock and mineral identification is ≤3 and the physical structure is clear, the transmittance of the quartz sand particles in the microscopic morphology observation exceeds 50% and the area of gas-liquid inclusions in the visible area does not exceed 5%, and at the same time, the SiO2 purity in the quartz sand after flotation is ≥99.9%, and at the same time, the SiO2 purity in the quartz sand after acid leaching is ≥99.998%.

[0014] Furthermore, the rock and mineral identification method includes observing the state of embedded minerals and the distribution of quartz grain size in a thin section of a granite pegmatite source rock and mineral using a polarizing microscope;

[0015] The thickness of the rock mineral slice is 28 microns to 32 microns.

[0016] Furthermore, when a polarizing microscope is used to observe that the particle size distribution of at least 70% of the quartz grains in each field of view of a rock and mineral thin section is such that the ratio of the average maximum size of the grains to the average minimum size of the grains is greater than 3, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

[0017] Furthermore, the particle size of the quartz sand made from the granite pegmatite source is between 70 mesh and 200 mesh;

[0018] The granite pegmatite ore source is made into quartz sand through the processes of crushing, grinding, roasting and water quenching.

[0019] Furthermore, the flotation reagent used in the flotation comprises at least one of dodecylamine, a composite collector and sodium oleate;

[0020] The adjusting agent used in the flotation comprises hydrofluoric acid.

[0021] Furthermore, the method of observing the microscopic morphology includes observing the microscopic morphology through a polarizing microscope;

[0022] When a polarizing microscope is used to observe that at least 30% of the quartz grains in the field of view of the quartz sand after flotation contain fluid inclusions with a volume percentage of more than 5%, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

[0023] Furthermore, the method for detecting the impurity content includes detecting the impurity content by ICP-OES equipment.

[0024] Furthermore, the acid solution used in the acid leaching includes a mixed acid solution consisting of hydrofluoric acid, nitric acid and hydrochloric acid.

[0025] Furthermore, the acid leaching temperature is not less than 80° C., and the acid leaching time is not less than 480 minutes.

[0026] In a second aspect, an application of any of the screening methods described above in the preparation of 4N8 grade high-purity quartz sand.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The present invention provides a method for screening granite pegmatite sources for high-purity quartz sand. The method systematically analyzes the granite pegmatite source through purified product test results and microscopic morphology observation to determine whether the source has the potential for purifying high-purity quartz sand, and can effectively screen whether the granite pegmatite source can be used as a potential raw material for preparing 4N8-grade high-purity quartz sand. In the present invention, purification and observation are carried out simultaneously, and the two complement each other. Specifically, for small-scale laboratory purification, a simple and feasible process is adopted to prepare high-purity quartz sand from the granite pegmatite source through conventional applicable means (such as crushing, scrubbing, roasting and water quenching, magnetic separation, flotation, and acid leaching). At the same time, combined with the observation and identification of the embedded minerals and fluid inclusions in the quartz ore and its quartz sand (such as observation and identification through a polarizing microscope), the feasibility of preparing 4N8-grade high-purity quartz sand from the granite pegmatite source can be efficiently evaluated from the overall perspective, and unfeasible / non-potential quartz sources can be eliminated in advance to a certain extent, thereby helping to reduce the investment of time and other costs.

[0029] The application of the screening method for granite pegmatite ore sources for high-purity quartz sand provided by the present invention is beneficial to improving the purity of quartz sand to meet the demand for high-purity silicon materials in the electronics, optics and chemical industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A physical picture of a hand specimen of India A mine provided in Example 1 of the present invention;

[0032] Figure 2 The optical slice of Indian A ore provided in Example 1 of the present invention;

[0033] Figure 3 The XRD pattern of Indian ore A provided in Example 1 of the present invention;

[0034] Figure 4 This is a microscopic observation image of Indian A ore after flotation provided in Example 1 of the present invention;

[0035] Figure 5 This is a microscopic observation image of Indian A ore after acid leaching provided in Example 1 of the present invention;

[0036] Figure 6 This is a test diagram of a glass column from an Indian mine A provided in Example 1 of the present invention;

[0037] Figure 7 A physical picture of a hand specimen of Indian B ore provided in Example 2 of the present invention;

[0038] Figure 8 The optical slice of Indian B ore provided in Example 2 of the present invention;

[0039] Figure 9 This is a microscopic observation image of Indian B ore provided in Example 2 of the present invention;

[0040] Figure 10 The XRD pattern of Indian ore B provided in Example 2 of the present invention;

[0041] Figure 11 This is a microscopic observation image of Indian B ore after flotation provided in Example 2 of the present invention;

[0042] Figure 12 A physical picture of a hand specimen of Indian C ore provided in Example 3 of the present invention;

[0043] Figure 13 The optical slice of Indian C ore provided in Example 3 of the present invention;

[0044] Figure 14 The XRD pattern of Indian C ore provided in Example 3 of the present invention;

[0045] Figure 15 This is a microscopic observation image of Indian C ore after acid leaching provided in Example 3 of the present invention;

[0046] Figure 16 This is a test diagram of the glass pillars of the Indian C mine provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] According to a first aspect of the present invention, a method for screening a granite pegmatite source for high-purity quartz sand is provided, comprising the following steps:

[0049] Performing rock and mineral identification on a granite pegmatite ore source, sequentially performing magnetic separation and flotation on quartz sand produced from the granite pegmatite ore source to obtain flotation-extracted quartz sand, performing microscopic morphology observation and impurity content testing on the flotation-extracted quartz sand, performing acid leaching on the flotation-extracted quartz sand to obtain acid-leached quartz sand, and performing microscopic morphology observation and impurity content testing on the acid-leached quartz sand;

[0050] Granite pegmatite ore sources that meet the following conditions can be used as raw materials for 4N8 grade high-purity quartz sand:

[0051] When the number of embedded mineral types in rock and mineral identification is ≤3 and the phase structure is clear (clear phase structure means that the phase is clearly visible and the type of mineral can be directly determined by observation), the transmittance of quartz sand particles in microscopic morphology observation exceeds 50% and the area of gas-liquid inclusions in the visible area does not exceed 5%, and at the same time, the SiO2 purity in quartz sand after flotation is ≥99.9%, and at the same time, the SiO2 purity in quartz sand after acid leaching is ≥99.998%.

[0052] In the present invention, purification and observation are carried out simultaneously, and the two complement each other. For small-scale purification in the laboratory, a simple and feasible process is adopted to prepare high-purity quartz sand from granite pegmatite quartz ore sources through conventional applicable means (such as crushing, scrubbing, roasting and water quenching, magnetic separation, flotation and acid leaching). At the same time, combined with the observation and identification of the embedded minerals and fluid inclusions in the quartz ore and its quartz sand (such as observation and identification through polarizing microscope), the feasibility of preparing 4N8 grade high-purity quartz sand from granite pegmatite ore sources can be efficiently evaluated from the overall perspective, and unfeasible / non-potential quartz ore sources can be eliminated in advance to a certain extent, thereby helping to reduce the investment of time and other costs.

[0053] In a preferred embodiment, the method of rock and mineral identification includes but is not limited to observing the state of embedded minerals and the distribution of quartz grain size in rock and mineral thin sections of granite pegmatite sources through a polarizing microscope.

[0054] In the present invention, the selected granite pegmatite ore (i.e., ore source) can be first observed by hand specimen, and then the palm-sized ore is sliced and ground to form rock and mineral thin sections, and then the rock and mineral thin sections are subjected to rock and mineral identification under a polarizing microscope.

[0055] It should be noted that by observing the granite pegmatite hand specimens, morphological features such as iron impregnation, dark mineral embedding, and oily luster distribution can be observed on its surface. The specific scrubbing or crushing process can be selected according to the observation situation. For example, when obvious iron impregnation is observed, oxalic acid can be used for scrubbing. If severe weathering is observed or the mud content on the ore surface is high, multiple rounds of scrubbing can be performed to avoid affecting the efficiency of subsequent magnetic separation or flotation processes.

[0056] In a preferred embodiment, the thickness of the rock mineral slice can be 28 microns to 32 microns, and its typical but non-limiting thickness is, for example, 28 microns, 29 microns, 30 microns, 31 microns, and 32 microns. The distribution and type of embedded minerals and the distribution of quartz grain size are observed by polarizing microscopy.

[0057] It should be noted that if the impurity minerals are in or dispersed inside the quartz grains, other crushing methods (such as roller sand making) should be considered; when observing the particle size of quartz grains, if the particle size difference between different particles in the same field of view is large, the possibility of a low sand making yield should be considered, and multiple rounds of small-scale sand making-screening-re-sand making process can be selected to save materials.

[0058] In a preferred embodiment, when a polarizing microscope is used to observe the entire rock and mineral thin section, it is found that at least 70% of the quartz grains in each field of view have a large difference in particle size, that is, the ratio of the average maximum size of the grains to the average minimum size of the grains is greater than 3. In this case, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

[0059] In the present invention, granite pegmatite ore can be subjected to XRD and XRF analysis to obtain its chemical composition and phase structure. The SiO2 content in granite pegmatite is generally between 60% and 70%, and the quartz content is generally between 25% and 40%. Through the combined analysis of XRD and XRF, the content of common impurity minerals can be detected within a certain range, thereby establishing the process parameters for subsequent magnetic separation and flotation. For example, when the mica content accounts for more than 50% of the total impurity mineral content, mica should be used as the main reverse flotation mineral. When the feldspar content accounts for more than 50% of the total impurity mineral content, in order to avoid the feldspar from becoming clay-forming during the roasting process, the specific process sequence needs to be adjusted to implement a process flow of crushing and scrubbing - magnetic separation - flotation - roasting and water quenching - acid washing.

[0060] In a preferred embodiment, the granite pegmatite source can be made into quartz sand particles through the processes of crushing, grinding, roasting and water quenching.

[0061] In the present invention, granite pegmatite ore (i.e., ore source) can be processed into quartz sand particles with a particle size of 70-200 meshes by a jaw crusher, a vertical mill, and a roasting and water quenching device. The quartz sand particles are then magnetically separated by a magnetic field strength of 2T. The process can be circulated twice to remove the concentrate, thereby obtaining magnetically separated quartz sand. The magnetically separated quartz sand is then flotated, and hydrofluoric acid, dodecylamine, a composite collector, and sodium oleate can be selected as reagents for the flotation to obtain flotated quartz sand.

[0062] In a preferred embodiment, after flotation, the quartz sand can be tested for various impurity contents using an ICP-OES device, and its microscopic morphology can be observed using a polarizing microscope. In this case, the quartz sand particles under the polarizing microscope are the main reference objects for the mineral source. Under the polarizing microscope, it can be seen whether the quartz sand carries other impurity minerals, the distribution of fluid inclusions, and the aspect ratio of the quartz sand particles.

[0063] In a preferred embodiment, when it is observed through a polarizing microscope that at least 30% of the quartz grains in the field of view of the quartz sand after flotation contain fluid inclusions with a volume percentage of more than 5%, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

[0064] In the present invention, the quartz sand after flotation is subjected to high-purity acid leaching to obtain acid-leached quartz sand.

[0065] In a preferred embodiment, after high-purity acid leaching, high-purity quartz sand after acid leaching is obtained, and its impurity content can be detected by ICP-OES equipment, and its microscopic morphology can be observed by polarizing microscope.

[0066] In a preferred embodiment, the acid solution used in high-purity acid leaching can be a mixed acid solution of hydrofluoric acid, nitric acid and hydrochloric acid, but is not limited to it; at the same time, the equipment used in high-purity acid leaching can be a reciprocating shaking reactor, but is not limited to it.

[0067] In a preferred embodiment, the temperature of the high-purity acid leaching may be no less than 80° C., and the time of the high-purity acid leaching may be no less than 480 minutes.

[0068] In summary, the present invention mainly focuses on small-scale purification in the laboratory, adopts a simple and feasible process, and targets high-purity quartz ore sources. While purifying and preparing high-purity quartz sand, it combines rock and mineral identification methods such as polarizing microscopy, and efficiently evaluates (screens) the feasibility of preparing 4N8 grade high-purity quartz sand from quartz ore sources as a whole. Therefore, it can eliminate unfeasible / non-potential quartz ore sources in advance to a certain extent, reducing the investment of time and other costs.

[0069] According to a second aspect of the present invention, there is provided an application of any of the above-mentioned screening methods in the preparation of 4N8 grade high-purity quartz sand.

[0070] The application of the screening method for granite pegmatite ore sources for high-purity quartz sand provided by the present invention is beneficial to improving the purity of quartz sand to meet the demand for high-purity silicon materials in the electronics, optics and chemical industries.

[0071] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0072] Example 1

[0073] A method for screening a granite pegmatite source for high-purity quartz sand, wherein the source is an Indian A mine, comprises the following steps:

[0074] (1) Observation and identification of rocks and minerals:

[0075] Rock and mineral observation: Hand specimens are observed mainly with the naked eye and a handheld microscope, mainly focusing on observing dark mineral embedding, iron impregnation and weathering phenomena, such as Figure 1 As shown, through observation of hand specimens, it can be found that the Indian A mine as a whole has ring-shaped iron disseminated layers, large sheets of layered mica and feldspar with an oily luster, and is partially weathered;

[0076] Identification of rock and minerals: The quartz grains of Indian ore A are intact, and the intercrystalline cracks of quartz are mainly filled with mica and feldspar. The rock and mineral thin sections are observed by polarizing microscope, such as Figure 2As shown, quartz exhibits wavy extinction, and the embedded minerals are mainly feldspar and mica. Feldspar is mainly embedded between quartz grains, and mica mainly fills the gaps between quartz and feldspar or is replaced at the edges of quartz. There are a small amount of columnar minerals and black opaque minerals. Fluid inclusions have beaded, striped, and diffuse shapes depending on their distribution.

[0077] (2) Physical structure:

[0078] The gangue minerals in India A mine are quartz, mica and feldspar, such as Figure 3 As shown, the content of muscovite is about 7.03%, phlogopite is about 1.22%, feldspar is about 4.5%, and magmacite is about 4.98%. The subsequent operation is the process of crushing and scrubbing - grinding and sand making - roasting and water quenching - magnetic separation - flotation - acid leaching.

[0079] (3) Physical selection:

[0080] Crushing process: Use a small jaw crusher (the crusher is made of zirconia) to crush the ore source. The particle size after crushing is about 0.5cm-1cm;

[0081] Scrubbing process: Use scrubbing process to remove weathered materials on the surface. The scrubbing medium is 5% oxalic acid solution and the scrubbing time is 2 minutes.

[0082] Grinding sand making process: Use zirconia vibrating mill for 30s, grind and screen through plastic frame and nylon screen standard sieve, and cycle grinding until the particle size is between 70 mesh and 200 mesh;

[0083] Roasting and water quenching process: The obtained grinding product is calcined at 900℃ for 1 hour to activate the dark impurity minerals to reduce the difficulty of subsequent impurity removal and obtain quartz sand particles;

[0084] Magnetic separation process: The obtained quartz sand particles are subjected to a magnetic separation process to remove magnetic minerals to obtain magnetically separated quartz sand;

[0085] Flotation process: The quartz sand after magnetic separation is subjected to flotation process, and hydrofluoric acid is used as an adjusting agent to adjust the pH of the flotation system to 2-3, and dodecylamine is added for reverse flotation. The dosage of dodecylamine is 200g / t, and 4ml is added until no obvious impurities float out; hydrofluoric acid is used as an adjusting agent to adjust the pH of the flotation system to 2-3, and composite collector A (prepared by propylene diamine, sodium petroleum sulfonate and sodium dodecyl sulfonate in a mass ratio of 1:1:1) is added for reverse flotation. The dosage is 200g / t, and 2ml is added; the composite collector A is added. Collector A is added in an amount of 100 g / t and 1 ml; hydrofluoric acid is used as a regulator to adjust the pH of the flotation system to 2-3, and composite collector B (prepared from sodium petroleum sulfonate and sodium α-olefin sulfonate in a mass ratio of 1:1) is added in an amount of 200 g / t and 2 ml for reverse flotation; composite collector B is added in an amount of 100 g / t and 1 ml; the system is diluted with deionized water to a pH of 4-5, and sodium oleate is added in an amount of 200 g / t and 2 ml; quartz sand after flotation is obtained;

[0086] (4) Microscopic morphology observation and impurity content detection of quartz sand after flotation:

[0087] Microscopic morphology observation: The microscopic morphology was observed through a polarizing microscope. Under the microscope, it was observed that more than half of the quartz sand particles were transparent particles, such as Figure 4 As shown, the particles have good light transmittance, and about 20% appear as white slightly translucent particles. The particles with well-developed single crystals and few internal impurities usually appear as highly transparent quartz particles. Some particles appear non-transparent, which may be because the gas-liquid inclusions affect the light transmittance of this area.

[0088] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after flotation are shown in Table 1. The purity of SiO2 in the quartz sand after flotation is greater than 99.9%;

[0089] Table 1 Impurity content of India A ore after flotation

[0090]

[0091] (5) Chemical separation-acid leaching process:

[0092] The acid leaching conditions are as follows:

[0093] The solid-liquid ratio of acid leaching is 1:5;

[0094] The acid solution used for acid leaching is a mixed acid solution of HF 0.5mol / L, HCl 1mol / L and HNO3 1mol / L;

[0095] The acid leaching temperature is 80°C and the acid leaching time is 6 hours;

[0096] A constant temperature oscillator was used to ensure sufficient reaction;

[0097] (6) Microscopic morphology observation and impurity content detection of quartz sand after acid leaching:

[0098] Microscopic morphology observation: The inclusions in the quartz sand after acid leaching were observed and analyzed using a polarizing microscope. The quartz grains were not stained in color, and the number of gas-liquid inclusions visible inside the grains was small. Figure 5 As shown;

[0099] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after acid leaching are shown in Table 2. The purity of SiO2 in the quartz sand after acid leaching is greater than 99.998%, that is, the purity is greater than 4N8;

[0100] Table 2 Impurity content of Indian A ore after acid leaching

[0101]

[0102] (7) Vitreous column test:

[0103] The Indian A ore contains quartz, feldspar and mica minerals. After purification, the quartz sand particles are transparent, with good inclusions and good size. It has high potential for preparing crucible sand. The purity of the measured sample after purification is as high as 4N8, and the molten glass column is close to the standard sample, such as Figure 6 As shown, the left is the standard sample, and the right is the purified sample from India A mine;

[0104] (8) Conclusion:

[0105] In the rock and mineral identification of India A Mine, the types of embedded minerals are ≤3 and the phase structure is clear. In the microscopic morphology observation, the transmittance of quartz sand particles exceeds 50% and the area of gas-liquid inclusions in the visible area does not exceed 5%. At the same time, the SiO2 purity in the quartz sand after flotation is ≥99.9%, and the SiO2 purity in the quartz sand after acid leaching is ≥99.998%. Therefore, India A Mine can be used as a raw material for 4N8 grade high-purity quartz sand.

[0106] Example 2

[0107] A method for screening a granite pegmatite source for high-purity quartz sand, wherein the source is an Indian B ore, comprises the following steps:

[0108] (1) Observation and identification of rocks and minerals:

[0109] Rock and mineral observation: India B mine is a granite pegmatite type quartz raw material, such as Figure 7 As shown, through observation of hand specimens, it can be seen that there are a lot of feldspar and some layered mica minerals embedded, and some quartz is weathered;

[0110] Rock and mineral identification: The quartz grains of Indian B ore are intact, and the associated gangue minerals are mainly feldspar; the rock and mineral thin sections are observed by polarizing microscope, such as Figure 8 As shown, quartz exhibits wavy extinction, and most feldspars are independent minerals. Some feldspars and mica are filled in the quartz cracks or replaced at the edges of quartz. The aspect ratio of quartz grains is reasonable.

[0111] Microscopic observation of raw ore: Figure 9 As shown in the figure, there are relatively few inclusions in the original ore of Indian B ore, and the fluid inclusions are in the form of beads, strips and dispersions according to their distribution state.

[0112] (2) Physical structure:

[0113] The gangue minerals in India B mine are quartz, mica and feldspar, such as Figure 10 As shown, the potassium feldspar content is about 19.48% and the sodium feldspar content is about 13.00%. The subsequent operation is the process of crushing and scrubbing - grinding and sand making - magnetic separation - flotation - roasting and water quenching - acid leaching;

[0114] (3) Physical selection:

[0115] Crushing process: Use a small jaw crusher (the crusher is made of zirconia) to crush the ore source. The particle size after crushing is about 0.5cm-1cm;

[0116] Scrubbing process: Use scrubbing process to remove weathered materials on the surface. The scrubbing medium is water and the scrubbing time is 2 minutes.

[0117] Grinding sand making process: Use zirconia vibrating mill for 30s, grind and screen through plastic frame and nylon screen standard sieve, and cycle grinding until the particle size is between 70 mesh and 200 mesh;

[0118] Magnetic separation process: The obtained quartz sand particles are subjected to a magnetic separation process to remove magnetic minerals to obtain magnetically separated quartz sand;

[0119] Flotation process: The quartz sand after magnetic separation is subjected to flotation process;

[0120] Primary flotation process: using hydrofluoric acid as a regulator, adjust the pH of the flotation system to 2-3, add dodecylamine at a dosage of 200 g / t and 4 ml for reverse flotation, until no obvious impurities float out; using hydrofluoric acid as a regulator, adjust the pH of the flotation system to 2-3, add composite collector A (prepared by propylene diamine, sodium petroleum sulfonate and sodium dodecyl sulfonate in a mass ratio of 1:1:1) at a dosage of 200 g / t and 2 ml for reverse flotation; add composite collector A at a dosage of 100 g / t and 1 ml; dilute the system to pH 4-5 with deionized water, add sodium oleate at a dosage of 200 g / t and 2 ml;

[0121] Secondary flotation process: using hydrofluoric acid as an adjusting agent, the pH of the flotation system is adjusted to 2-3, and dodecylamine is added for reverse flotation. The dosage of dodecylamine is 200g / t, and 2ml is added until no obvious impurities float out; using hydrofluoric acid as an adjusting agent, the pH of the flotation system is adjusted to 2-3, and composite collector A is added for reverse flotation. The dosage is 100g / t and 1ml is added; using hydrofluoric acid as an adjusting agent, the pH of the flotation system is adjusted to 2-3, and composite collector B (prepared by sodium petroleum sulfonate and sodium α-olefin sulfonate in a mass ratio of 1:1) is added for reverse flotation. The dosage is 100g / t and 1ml is added; and quartz sand after flotation is obtained.

[0122] (4) Microscopic morphology observation and impurity content detection of quartz sand after flotation:

[0123] Microscopic morphology observation: The microscopic morphology of quartz sand after secondary flotation under a polarizing microscope is as follows Figure 11 As shown;

[0124] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after flotation are shown in Table 3. The purity of SiO2 in the quartz sand after flotation is greater than 99.9%;

[0125] Table 3 Impurity content of Indian B ore after flotation

[0126]

[0127] Calcination and water quenching process: Most of the clay minerals, mica, feldspar, etc. have been removed in the early treatment process, so calcination is carried out at 900℃ for 1h;

[0128] (5) Chemical separation-acid leaching process:

[0129] The acid leaching conditions are as follows:

[0130] The solid-liquid ratio of acid leaching is 1:4;

[0131] The acid solution used for acid leaching is a mixed acid solution of HF 1.0mol / L, HCl 0.5mol / L and HNO3 1.0mol / L;

[0132] The acid leaching temperature is 80°C and the acid leaching time is 8h;

[0133] A constant temperature oscillator was used to ensure sufficient reaction;

[0134] (6) Microscopic morphology observation and impurity content detection of quartz sand after acid leaching:

[0135] Microscopic morphology observation: The inclusions of the quartz sand after acid leaching were observed and analyzed using a polarizing microscope. The quartz grains showed no obvious dissemination, and few solid inclusions or gas-liquid inclusions were found inside the grains. The aspect ratio of the quartz sand particles was reasonable.

[0136] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after acid leaching are shown in Table 4. The purity of SiO2 in the quartz sand after acid leaching is greater than 99.998%, that is, the purity is greater than 4N8;

[0137] Table 4 Impurity content of Indian B ore after acid leaching

[0138]

[0139] (7) Conclusion:

[0140] Indian ore B contains quartz, feldspar, and mica, with feldspar accounting for a high proportion. After purification, the quartz sand particles are transparent, with good inclusions and good size. It has high potential for producing 4N8 grade high-purity quartz sand. The purity of the measured sample after purification is as high as 5N.

[0141] In the rock and mineral identification of India B ore, the types of embedded minerals are ≤3 and the phase structure is clear. In the microscopic morphology observation, the transmittance of quartz sand particles exceeds 50% and the area of gas-liquid inclusions in the visible area does not exceed 5%. At the same time, the SiO2 purity in the quartz sand after flotation is ≥99.9%, and the SiO2 purity in the quartz sand after acid leaching is ≥99.998%. Therefore, India B ore can be used as a raw material for 4N8 grade high-purity quartz sand.

[0142] Example 3

[0143] A method for screening a granite pegmatite source for high-purity quartz sand, wherein the source is Indian C ore, comprises the following steps:

[0144] (1) Observation and identification of rocks and minerals:

[0145] Rock and mineral observation: India C mine is a granite pegmatite type quartz raw material, such as Figure 12 As shown, through the observation of hand specimens, it can be seen that there are a lot of layered mica minerals and some oily feldspar inlaid;

[0146] Rock and mineral identification: The quartz grains of Indian C ore are intact, and the associated gangue minerals are mainly mica and feldspar; the rock and mineral thin sections are observed by polarizing microscope, such as Figure 13 As shown, quartz exhibits wavy extinction, and most of the mica and feldspar are independent minerals. At the same time, columnar minerals appear inside some grains, and the aspect ratio of the quartz grains is reasonable.

[0147] (2) Physical structure:

[0148] The main minerals in Indian C ore are quartz, mica and feldspar, such as Figure 14 As shown, the content of albite is about 9.38%, plagioclase is about 12.49%, muscovite is about 7.55%, and biotite is about 2.57%. The subsequent operation is the process of crushing and scrubbing - grinding and sand making - magnetic separation - flotation - roasting and water quenching - acid leaching.

[0149] (3) Physical selection:

[0150] Crushing process: Use a small jaw crusher (the crusher is made of zirconia) to crush the ore source. The particle size after crushing is about 0.5cm-1cm;

[0151] Scrubbing process: the scrubbing medium is water, and the scrubbing time is 2 minutes;

[0152] Grinding sand making process: Use zirconia vibrating mill for 30s, grind and screen through plastic frame and nylon screen standard sieve, and cycle grinding until the particle size is between 70 mesh and 200 mesh;

[0153] Magnetic separation process: The obtained quartz sand particles are subjected to a magnetic separation process to remove magnetic minerals to obtain magnetically separated quartz sand;

[0154] Flotation process: The quartz sand after magnetic separation is subjected to flotation process;

[0155] Using hydrofluoric acid as a regulating agent, the pH of the flotation system is adjusted to 2-3, and dodecylamine is added for reverse flotation at a dosage of 200 g / t and 4 ml until no obvious impurities float out; using hydrofluoric acid as a regulating agent, the pH of the flotation system is adjusted to 2-3, and composite collector A (prepared by propylene diamine, sodium petroleum sulfonate, and sodium dodecyl sulfonate in a mass ratio of 1:1:1) is added for reverse flotation at a dosage of 200 g / t and 2 ml; composite collector B (prepared by sodium petroleum sulfonate and sodium α-olefin sulfonate in a mass ratio of 1:1) is added for reverse flotation at a dosage of 200 g / t and 1 ml; the system is diluted with deionized water to a pH of 4-5, and sodium oleate is added at a dosage of 200 g / t and 2 ml;

[0156] (4) After flotation, the quartz sand is tested for impurity content:

[0157] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after flotation are shown in Table 5. The purity of SiO2 in the quartz sand after flotation is greater than 99.9%;

[0158] Table 5 Impurity content of Indian C ore after flotation

[0159]

[0160] Calcination and water quenching process: mica, feldspar, etc. have been basically removed in the early treatment process, so calcination is carried out at 900℃ for 1h;

[0161] (5) Chemical separation-acid leaching process:

[0162] The acid leaching conditions are as follows:

[0163] The solid-liquid ratio of acid leaching is 1:4;

[0164] The acid solution used for acid leaching is a mixed acid solution of HF 1.0mol / L, HCl 1.0mol / L and HNO3 1.0mol / L;

[0165] The acid leaching temperature is 80°C and the acid leaching time is 8h;

[0166] A constant temperature oscillator was used to ensure sufficient reaction;

[0167] (6) Microscopic morphology observation and impurity content detection of quartz sand after acid leaching:

[0168] Microscopic morphology observation: Use polarizing microscope to observe and analyze the inclusions of quartz sand after acid leaching, such as Figure 15 As shown, there is no obvious dissemination in the color of the quartz grains, and obvious gas-liquid inclusions can be seen inside the grains;

[0169] Impurity content detection: The impurity content was detected by ICP-OES equipment. The impurity content detection results in the quartz sand after acid leaching are shown in Table 6. The purity of SiO2 in the quartz sand after acid leaching is 99.996%, that is, the purity is ≥4N6;

[0170] Table 6 Impurity content of Indian C ore after acid leaching

[0171]

[0172] (7) Vitreous column test:

[0173] The Indian C ore contains quartz, feldspar and mica minerals. After purification, the quartz sand particles are transparent and the inclusions are average. The purity of the measured sample after purification reaches 4N6. The molten glass column has a certain gap from the standard sample, such as Figure 16 As shown, the left is the standard sample, and the right is the purified sample of Indian C ore;

[0174] (8) Conclusion:

[0175] Indian C ore contains quartz, feldspar, and mica, with feldspar accounting for a high proportion. After purification, the quartz sand particles are transparent and of good size, and have high potential for the production of 4N6 grade high-purity quartz sand.

[0176] The SiO2 purity of quartz sand after flotation of Indian C ore is ≥99.9%, and the SiO2 purity of quartz sand after acid leaching is ≥99.996%. However, rock and mineral identification found that there are more than 3 types of embedded minerals, and microscopic morphology observation found that the area of gas-liquid inclusions in the visible area of quartz sand particles accounts for more than 5%. Combined with the results of glass column tests, Indian C ore cannot be used as a raw material for 4N8 grade high-purity quartz sand.

[0177] In summary, the present invention adopts a simple and feasible process to prepare high-purity quartz sand from granite pegmatite quartz ore sources through conventional applicable means (such as crushing, scrubbing, roasting and water quenching, magnetic separation, flotation and acid leaching). At the same time, combined with the observation and identification of the embedded minerals and fluid inclusions in the quartz ore and its quartz sand (such as observation and identification through polarizing microscope), the feasibility of preparing 4N8 grade high-purity quartz sand from granite pegmatite ore sources can be efficiently evaluated from an overall perspective, and unfeasible / non-potential quartz ore sources can be eliminated in advance to a certain extent, which is conducive to reducing the investment of time and other costs.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for screening granite pegmatite ore sources for high-purity quartz sand, characterized in that: The following steps are involved: Performing rock and mineral identification on a granite pegmatite ore source, sequentially performing magnetic separation and flotation on quartz sand prepared from the granite pegmatite ore source to obtain flotation-extracted quartz sand, performing microscopic morphology observation and impurity content detection on the flotation-extracted quartz sand, performing acid leaching on the flotation-extracted quartz sand to obtain acid-leached quartz sand, and performing microscopic morphology observation and impurity content detection on the acid-leached quartz sand; The granite pegmatite ore source, as the raw material of 4N8 grade high-purity quartz sand, meets the following conditions: When the number of embedded mineral types in the rock and mineral identification is ≤3 and the physical structure is clear, the transmittance of the quartz sand particles in the microscopic morphology observation exceeds 50% and the area of gas-liquid inclusions in the visible area does not exceed 5%, and at the same time, the SiO2 purity in the quartz sand after flotation is ≥99.9%, and at the same time, the SiO2 purity in the quartz sand after acid leaching is ≥99.998%.

2. The screening method according to claim 1, wherein The rock and mineral identification method includes observing the state of embedded minerals and the distribution of quartz grain size in the rock and mineral thin sections of the granite pegmatite ore source through a polarizing microscope; The thickness of the rock mineral slice is 28 microns to 32 microns.

3. The screening method according to claim 2, characterized in that When the particle size distribution of at least 70% of the quartz grains in each field of view of the rock and mineral thin section observed through a polarizing microscope shows that the ratio of the average maximum size of the grains to the average minimum size of the grains is greater than 3, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

4. The screening method according to any one of claims 1 to 3, characterized in that The particle size of the quartz sand made from granite pegmatite ore source is between 70 mesh and 200 mesh; The granite pegmatite ore source is made into quartz sand through the processes of crushing, grinding, roasting and water quenching.

5. The screening method according to claim 1, wherein The flotation reagent used in the flotation comprises at least one of dodecylamine, a composite collector and sodium oleate; The adjusting agent used in the flotation comprises hydrofluoric acid.

6. The screening method according to claim 1, wherein The method of observing the microscopic morphology includes observing the microscopic morphology through a polarizing microscope; When a polarizing microscope is used to observe that at least 30% of the quartz grains in the field of view of the quartz sand after flotation contain fluid inclusions with a volume percentage of more than 5%, the granite pegmatite source cannot be used as a raw material for 4N8 grade high-purity quartz sand.

7. The screening method according to claim 1, wherein The method for detecting the impurity content includes detecting the impurity content by ICP-OES equipment.

8. The screening method according to claim 1, wherein The acid solution used in the acid leaching includes a mixed acid solution consisting of hydrofluoric acid, nitric acid and hydrochloric acid.

9. The screening method according to claim 8, characterized in that The acid leaching temperature is not less than 80° C., and the acid leaching time is not less than 480 minutes.

10. Use of the screening method according to any one of claims 1 to 9 in the preparation of 4N8 grade high-purity quartz sand.

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