Method for determining total amount of impurity elements in natural high-purity quartz mineral

Abstract

The invention relates to a method for determining the total amount of impurity elements in a natural high-purity quartz mineral, which comprises the following steps of: preparing a laser sheet of the quartz mineral, observing and photographing by using a polarizing microscope, designing an analysis test point on a picture, and carrying out point-by-point analysis and determination on a laser ablation and inductively coupled plasma spectrum according to the design point. Accurate determination of impurity elements of quartz minerals in a natural high-purity quartz raw material is realized, comprehensive analysis and evaluation are carried out, and grade characteristics of the quartz minerals in the high-purity quartz raw material are further determined. The method is suitable for analysis and determination of impurity elements in natural quartz minerals, has the advantages of low detection limit, high sensitivity, wide linear range and the like, can be applied to effective and rapid evaluation, quality monitoring and the like of high-purity quartz raw materials, and provides quartz mineral raw materials with stable grades for the high-purity quartz sand industry.

Description

Technical Field

[0001] This invention relates to a method for determining the total amount of impurity elements in natural high-purity quartz minerals. The method involves obtaining samples through in-situ micro-area ablation using a laser ablation system, followed by analysis and determination of elemental content using plasma mass spectrometry. Combined with microscopic petrographic observation of fluid inclusions in quartz minerals, the grade of the quartz mineral raw materials is comprehensively evaluated. Background Technology

[0002] LA-ICP-MS in-situ micro-area analysis technology has a wide range of applications, including materials science, mineralogy, ore deposit geology, and isotope geochronology. In materials science, LA-ICP-MS obtains the elemental distribution characteristics of micro-areas. In mineralogy, it analyzes the trace element content characteristics of mineral growth zones. In ore deposit geology, it obtains the occurrence state and other characteristics of ore-forming elements. In isotope geochronology, it obtains isotopic dating information from terrestrial, meteorite, and extraterrestrial rock samples.

[0003] GB / T 32649-2016 "High-purity quartz sand for photovoltaic use" stipulates that the total content of impurity elements in high-purity quartz sand for photovoltaic use should be less than or equal to 25 μg / g, of which the total content of potassium, lithium and sodium should be less than 2.5 μg / g, and the content of each impurity element should comply with the provisions of Table 1.

[0004] Table 1 shows the content of each impurity element in micrograms per gram (μg / g).

[0005] impurity elements Permissible content Aluminum (Al) ＜20 Calcium (Ca) ＜1 Iron (Fe) ＜0.5 Sodium(Na) ＜1 Potassium (K) ＜1 Lithium (Li) ＜1 Magnesium (Mg) ＜0.5 Cadmium (Cr) ＜0.1 Nickel (Ni) ＜0.1 Boron (B) ＜0.1 Manganese (Mn) ＜0.2 Copper (Cu) ＜0.1 Titanium (Ti) ＜1.5

[0006] The particle size of high-purity quartz sand for photovoltaic applications should be in the range of 70μm to 350μm, and the cumulative mass fraction within this particle size range should be greater than or equal to 90%. The cumulative mass fraction of particles smaller than 100μm or larger than 300μm should be less than 1%.

[0007] While there are recommended testing methods for determining the content of impurity elements in high-purity quartz sand, namely ICP-MS (inductively coupled plasma optical microscopy), there is currently no effective method for determining the content of impurity elements in natural quartz minerals, the raw material for high-purity quartz sand. This hinders breakthroughs in the exploration of high-purity quartz raw material deposits and further impedes the mineral exploration and evaluation of high-purity quartz mineral raw materials. Therefore, an effective and rapid method for determining and comprehensively evaluating the impurity elements in high-purity quartz minerals is needed.

[0008] Therefore, developing an accurate, efficient, and applicable technique for the analysis and testing of lithium, boron, sodium, magnesium, aluminum, phosphorus, potassium, calcium, scandium, titanium, cadmium, manganese, iron, nickel, copper, zinc, germanium, rubidium, zirconium, tin, barium, tungsten, thallium, bismuth, and uranium in natural massive quartz minerals has become an urgent problem for analysts and evaluators. Summary of the Invention

[0009] The purpose of this invention is to develop an analytical method for determining lithium, boron, sodium, magnesium, aluminum, phosphorus, potassium, calcium, scandium, titanium, cadmium, manganese, iron, nickel, copper, zinc, germanium, rubidium, zirconium, tin, barium, tungsten, thallium, bismuth, and uranium in natural massive quartz minerals. This method involves preparing laser slides of quartz minerals, observing and photographing them using a polarizing microscope, designing analytical test points on the photographs, and conducting point-by-point analysis and determination using laser ablation and inductively coupled plasma spectroscopy (ICP-SPS). This allows for the accurate determination of impurity elements in quartz minerals from natural high-purity quartz raw materials, comprehensive analysis and evaluation, and further determination of the grade characteristics of quartz minerals in high-purity quartz raw materials.

[0010] To achieve the above objectives, the present invention provides a method for determining the total amount of impurity elements in natural high-purity quartz minerals, comprising the following steps:

[0011] S1, a localized section of a rock specimen, yielded three sections with thicknesses of T1 = 30 ± 5 μm, T2 = 80 ± 5 μm, and T3 = 150 ± 10 μm, all of which were single-sided polished.

[0012] S2. Using a polarizing microscope, the rock and mineral identification and petrographic observation of fluid inclusions were first performed on the T1 thin section. Then, the electron probe microanalysis (EMPA) of the T2 thin section, which is the probe section, was combined with the T3 thin section, which is the laser section, to quantitatively analyze the quartz minerals. The area where the quartz minerals are located in the T3 thin section, which is the laser section, was then circled and photographed.

[0013] S3, the field of view circled on the T3 thin section, the test points designed for use on the laser ablation inductively coupled plasma mass spectrometer on the reflected light photograph obtained by the image, with the center of the quartz mineral on the image as the center and the test points symmetrically arranged with an interval of 88-200 μm from the edge of the quartz mineral, the design radius of the test points is 44 μm, the number of test points is 5-12, and the design test points are evenly distributed throughout the quartz mineral particles on the image;

[0014] S4. The T3 thin film was placed in the sample chamber of the laser ablation inductively coupled plasma mass spectrometer for testing.

[0015] S5 processes the LA-ICP-MS test data of quartz minerals and outputs a report;

[0016] S6, further refine the trace element content of the output report, where the B and P content is corrected by dividing by 100, and the Ca content is corrected by dividing by 10;

[0017] S7. Calculate the total amount (μg / g) of the thirteen elements in GB / T 32649-2016 "High-purity Quartz Sand for Photovoltaics" or the fifteen elements in IOTA based on the corrected content data to determine the total amount of quartz mineral impurities.

[0018] Furthermore, this invention provides a method for determining the impurity elements lithium, boron, sodium, magnesium, aluminum, phosphorus, potassium, calcium, scandium, titanium, cadmium, manganese, iron, nickel, copper, zinc, germanium, rubidium, zirconium, tin, barium, tungsten, thallium, bismuth, and uranium in natural high-purity quartz minerals. The specific determination steps are as follows:

[0019] First, using a red marker, draw a red line segment centered on the quartz mineral to mark the slicing position on the block sample of high-purity quartz mineral. Then, using a cutting machine, cut out three rectangular rock samples (3.5cm (length) × 2.5cm (width) × 0.5cm (thickness)) along the red line segment. After polishing one side, use Canadian resin to attach the samples to a glass slide (5.0cm (length) × 2.5cm (width) × 0.2cm (thickness)). Number the samples on the three glass slides as T1, T2, and T3, respectively. Polish them to a uniform thickness, with T1 having a thickness of 30±5μm, T2 having a thickness of 80±5μm, and T3 having a thickness of 150±10μm.

[0020] The second step involves using a polarizing microscope to first identify the rock and mineral composition and observe the petrographic features of fluid inclusions on the T1 and T3 thin sections. Then, combined with electron probe microanalysis (EMPA) quantitative analysis of the T2 thin section, the distribution characteristics of quartz on the thin section and the nature of its associated minerals are determined. Detailed micro-petrographic analysis of fluid inclusions is performed on the T3 thin section, as the petrographic features of quartz fluid inclusions are crucial for determining the necessity of LA-ICP-MS analysis. Based on the first two steps, a fine (approximately 0.5 mm) delineator is used to circle the quartz mineral area on the T3 thin section (laser section). Generally, 2-3 test circles are drawn on one laser section (and numbered, e.g., 1, 2, 3). The test circles are generally 2.0-3.0 mm in diameter; too large a circle will make it difficult to find test points, while too small a circle will not provide enough test points. The laser section is then placed on the stage of the polarizing microscope and fixed. The objective stage of the polarizing microscope is then switched to a 10x objective lens. Align the objective lens with the center of the numbered test circle on the laser sheet. Rotate the stage and the focusing knob of the polarizing microscope until the center of the field of view under the microscope is basically aligned with the center of the test circle and the mineral in the field of view is clear. Keep the stage still, switch the light source to reflected light, and the optical type to single polarized light. Fine-tune the focus knob until the mineral in the center of the field of view is clearest. Click to take a picture and save. Keep the stage still, switch the light source to transmitted light, and the optical type to crossed polarized light. Fine-tune the focus until the mineral in the field of view is clearest. Click to take a picture and save.

[0021] The third step involves designing test points on the laser ablation inductively coupled plasma mass spectrometer (LASIK) based on the quartz mineral field of view circled on the T3 thin section and the corresponding reflected light photograph. The test points are approximately 44 μm in diameter.

[0022] The fourth step involved placing the T3 thin section into the sample chamber of a laser ablation inductively coupled plasma mass spectrometer (ICP-MS) for testing. The testing instrument consisted of a GeoLasHD 193nm laser ablation system and an Agilent 7900ICP-MS ICP-MS spectrometer, with a laser energy of 9±2 J / cm². 2 The laser frequency is 4±2Hz and the laser beam diameter is 44μm;

[0023] The fifth step is to process the LA-ICP-MS test data of quartz minerals using the software ICPMSDataCal 11.0, with the glass standard material NISTRAM 610 as an external standard to correct trace elements, and then output a report.

[0024] The sixth step is to further refine the trace element content of the output report, where the Be and P content is corrected by dividing by 100, and the Ca content is corrected by dividing by 10.

[0025] The seventh step involves calculating the total amount (μg / g) of the thirteen elements in GB / T 32649-2016 "High-purity Quartz Sand for Photovoltaics" or the fifteen elements in IOTA from the corrected content data. This determines the total amount of impurity elements in the quartz mineral. By comparing the data with domestic and international high-purity quartz industry standards and combining this with observation under a polarizing microscope to obtain the petrographic characteristics of fluid inclusions, the grade of the quartz mineral is comprehensively determined and evaluated.

[0026] The above-mentioned thin sections are localized sections of rock specimens, each a polished section of a specific thickness, without a cover glass.

[0027] Taking one photograph each of reflected light and crossed polarized light from the same field of view using a 10x objective lens is a key step in the design of quartz measuring points.

[0028] The operating conditions of the instruments used in the fourth step of the measurement are as follows:

[0029] Instrumentation: GeoLasHD 193nm laser ablation system + Agilent 7900ICP-MS inductively coupled plasma spectroscopy, laser energy 9±2J / cm² 2 The laser frequency is 4±2Hz and the laser beam diameter is 44μm. Helium is used as the carrier gas and argon as the compensation gas during the test. The two are mixed and enter the mass spectrometer through a T-shaped glass interface. A signal smoothing device is configured between the T-shaped glass interface and the laser ablation system.

[0030] The standard sample used in the fourth step of the determination is NISTRAM 610, while NISTRAM 612 and NISTRAM 614 are used as monitoring samples.

[0031] The fifth step of the determination is as follows: the elemental content calculation adopts the multiple external standard and no internal standard method (total normalization method), and Si of NISTRAM 610 standard is selected as the normalization element to eliminate the influence of laser ablation amount change on sensitivity drift.

[0032] The advantages of this invention are as follows:

[0033] 1. For the first time, the optimal thickness (150±10μm) of the probe sheet T3 for laser ablation plasma mass spectrometry analysis of quartz minerals was explored and clarified. This is superior to normal probe sheets, which are prone to being penetrated or broken by the laser. The use of T3 is also better than using a light plate (thickness>0.5cm). A light plate that is too thick will not be penetrated or broken, but because it is opaque, it is difficult to accurately locate and design test points, which can easily lead to a low success rate in selecting and locating quartz minerals at the test points.

[0034] 2. For the first time, reflected light photographs taken with a 10x objective polarizing microscope were used as film, and transmitted light photographs of orthogonally polarized light from the same 10x objective were compared to design measurement points. This allows for rapid and accurate location of quartz and its designed measurement points during instrument testing, while clearly distinguishing quartz zoning and even quartz phases. It also avoids hitting adjacent non-quartz minerals. Most importantly, it enables the rapid and accurate location of designed points during instrument testing. Compared to conventional methods such as finding minerals after starting the test, which often takes an hour to find one quartz mineral and test one point, this method greatly improves testing efficiency. The number of test points per day can generally reach 110-200, which saves on the consumption of instrument operation resources, obtains more test data, and significantly reduces energy consumption per point.

[0035] 3. For the first time, the size of the laser spot and energy of laser ablation plasma mass spectrometry (T3 thin section) of natural massive quartz minerals were determined, as well as the range of laser ablation frequency. This reduced the failure rate of LA-ICP-MS testing of quartz minerals and improved the success rate of effective test points, with the effective test point rate reaching over 98%.

[0036] 4. Polarizing microscopy and laser ablation plasma mass spectrometry (LA-ICP-MS) are mature analytical instruments widely used in geology, mineral resources, and environmental fields. They have advantages such as low detection limits, high sensitivity, and wide linear range. They are particularly suitable for the effective and rapid evaluation of high-purity quartz mineral raw materials. The LA-ICP-MS analytical method used in this invention can simultaneously determine lithium, boron, sodium, magnesium, aluminum, phosphorus, potassium, calcium, scandium, titanium, cadmium, manganese, iron, nickel, copper, zinc, germanium, rubidium, zirconium, tin, barium, tungsten, thallium, bismuth, and uranium in natural massive quartz minerals. The method detection limits for each element are far lower than those in GB / T 32649-2016 "High-purity Quartz Sand for Photovoltaics" and the minimum content standards for high-purity quartz in the Unimin IOTA standard, which can meet the needs of daily production.

[0037] 5. The present invention has simple operation steps, low reagent consumption, fast analysis speed, stable analysis results, and no sample contamination (avoiding the drawbacks of ICP-MS testing methods using powdered quartz sand samples, where the impurities adsorbed by the quartz sand are not completely removed, resulting in high test impurity content and inaccuracy). It can accurately determine the total amount of impurity elements in natural quartz minerals. Further comprehensive research can also effectively determine the quality and product grade of natural quartz minerals. Attached Figure Description

[0038] Figure 1 Location diagram of a slice of a blocky sample of natural high-purity quartz mineral.

[0039] Figure 2 Fluid inclusions in natural high-purity quartz minerals under a polarizing microscope.

[0040] Figure 3 Location map of LA-ICP-MS measurement points for natural high-purity quartz minerals. Detailed Implementation

[0041] Example 1: The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to the present invention comprises the following steps:

[0042] The first step was to select sample No. 5, a high-purity quartz massive rock of grade 4N5 from the eastern Qinling Mountains. On this massive rock sample, the quartz mineral was selected and a line segment was drawn around the center. Figure 1 Using a cutting machine, three rectangular rock samples were cut from the marked lines. After smoothing the samples, Canadian resin was applied to glass slides. The samples on the glass slides were then polished to produce thin sections without coverslips, with thicknesses of 35μm, 85μm, and 160μm. The corresponding thin section numbers are No.5-T1, No.5-T2, and No.5-T3.

[0043] The second step involves using a polarizing microscope to identify the rock and mineral composition and fluid inclusions in thin sections No. 5-T1 and No. 5-T3. Figure 2 Petrographic observations, combined with electron probe microanalysis (EMPA) quantitative analysis of the No.5-T2 thin section (probe section), were used to determine the distribution characteristics of the No.5 quartz mineral on the thin section and the nature of its associated minerals. Furthermore, the petrographic characteristics of the fluid inclusions in the quartz minerals were used to determine whether LA-ICP-MS analysis of No.5 was necessary. Based on the previous two studies, three test circles for the quartz minerals were drawn on the No.5-T3 thin section (laser section) using an extremely fine (approximately 0.5 mm) oil-based pen. Figure 3Write 1, 2, and 3 next to the test circles on the three thin slices with a fine-tipped pen, and number the three test circles on the thin slices one by one as No.5-T3-1, No.5-T3-2, and No.5-T3-3, and record them in the notebook.

[0044] Then place No. 5-T3 on the stage of the polarizing microscope and fix it in place. At the same time, rotate the objective lens of the polarizing microscope to switch to 10x objective lens and align the 10x objective lens with the center of the test circle of No. 5-T3-1. By rotating the stage and the focusing knob of the polarizing microscope, make the center of the field of view under the microscope basically coincide with the center of the test circle until the mineral in the test circle of No. 5-T3-1 is clear. Keep the stage still, switch the light source to reflected light, and the optical type to single polarized light. Fine-tune the focus knob to make the mineral in the center of the field of view under the microscope as clear as possible. Click to take a picture and save the photo as No. 5-T3-1-(R); keep the stage still, switch the light source to transmitted light, and the optical type to crossed polarized light. Fine-tune the focus to make the mineral in the field of view under the microscope as clear as possible. Click to take a picture and save the photo as No. 5-T3-1-(+).

[0045] Next, import the two images, No. 5-T3-1-(R) and No. 5-T3-1-(+), into a CorelDRAW or PowerPoint presentation. Referring to the boundary between quartz and other minerals in the crossed polarized No. 5-T3-1-(+) image, design test points on the No. 5-T3-1-(R) image for use on a laser ablation inductively coupled plasma mass spectrometer. Figure 3 The test points are indicated by dashed circles. Seven test points are designed, and their distribution is approximately in a cross shape. The same operation is performed on No.5-T3-2-(R) and No.5-T3-3-(R) to obtain the corresponding test point design and the location map of the test points.

[0046] Fourth, No. 5-T3 was moved to the ultra-clean laboratory and placed in the sample chamber for LA-ICP-MS analysis. The testing instruments were a GeoLasHD 193nm laser ablation system and an Agilent 7900ICP-MS inductively coupled plasma mass spectrometer, with the laser energy set to 11 J / cm². 2The laser frequency was 4Hz, and the laser beam diameter was 44μm. According to the test point map, the laser was aimed at the designed points for analysis and testing. Before starting the analysis of the No.5-T3 design points, a set of standard samples (NISTRAM 610, NISTRAM 612 and NISTRAM 614) were analyzed first. Then, a set of standard samples was analyzed for every 10 test points before starting the test points of No.5-T3. After testing all the design points, another set of standard samples was tested for monitoring. The test cycle for each point was 90 seconds, of which the first 20 seconds were for preparing the test points, and the laser ablation was started for 20 seconds, lasting for 40 seconds. Throughout the process, helium gas was continuously flushed, and ICP-MS continuously received and recorded the count values ​​of elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U). The first 20 seconds are the background integration interval, and 25 of the remaining 40 seconds are selected as the test integration interval.

[0047] The fifth step involved analyzing three test zones for sample No. 5-T3, testing a total of 19 test points and 9 standard samples. The signal files of the test point and standard sample data were processed using ICPMSDataCal 11.0 software. The elemental content was calculated using the multiple external standard, no internal standard method, i.e., the total normalization method. Si from the NISTRAM 610 standard was selected as the normalization element to eliminate the influence of laser ablation amount variation on sensitivity drift.

[0048] Step 6: Use ICPMSDataCal 11.0 software No.5-T3 and standard sample processing to obtain results and output a report. If the element values ​​(Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U) of the standard samples (NISTRAM 610, NISTRAM 612, and NISTRAM 614) in the report are consistent with the known standard values ​​within the error range, then the test values ​​of the 19 points tested by No.5-T3 are valid.

[0049] The seventh step involves further processing the data from the 19 points of the No.5-T3 test. The contents of B and P elements are corrected by dividing by 100, and Ca is corrected by dividing by 10. The total amount of impurity elements in this batch of natural quartz mineral samples is 36.42±7.21μg / g. The specific element test results are shown in Table 2, No.5-T3.

[0050] Table 2. LA-ICP-MS Analysis Results of Impurity Elements in Typical High-Purity Quartz Samples

[0051]

[0052] "-" indicates the value is below the detection line; ∑ 12 =Al+K+Na+Li+Ca+Mg+Fe+Mn+Cu+Cr+Ni+B; ∑

[0053] 0=Sc+Ge+Zr+Sn+Ba+W+Tl+Bi+U; ∑ total (Total amount of impurity elements) = ∑ 12 +∑0.

[0054] Example 2, the method for determining the total amount of impurity elements in natural high-purity quartz minerals according to the present invention, comprises the following steps:

[0055] The first step involved selecting a 4N5 grade high-purity quartz block rock sample (SP) from Spruce-Pine, USA. On this block rock sample, a line segment was drawn centered on the selected quartz mineral. Three rectangular rock sections were then cut from this line using a cutting machine. After smoothing the sections, Canadian resin was applied to glass slides. The samples on the slides were then polished to create thin sections of 30μm, 80μm, and 150μm thickness without coverslips. These thin sections were designated SP-T1, SP-T2, and SP-T3.

[0056] The second step involves first using a polarizing microscope to identify the rock and mineral composition and observe the petrographic features of fluid inclusions on SP-T1 and SP-T3 thin sections. Then, combined with electron probe microanalysis (EMPA) quantitative analysis of the SP-T2 thin section (probe section), the distribution characteristics of the SP quartz minerals on the thin section and the nature of its associated minerals are determined. Furthermore, the petrographic features of the quartz fluid inclusions are the basis for determining whether LA-ICP-MS analysis of SP is necessary. Based on the first two steps, three test circles for the quartz minerals were drawn on the SP-T3 thin section (laser section) using an extremely fine (approximately 0.5 mm) oil-based pen. The three test circles were then labeled 1, 2, and 3 with the pen, and assigned corresponding numbers: SP-T3-1, SP-T3-2, and SP-T3-3, and recorded in a notebook.

[0057] Then place the SP-T3 on the stage of the polarizing microscope and fix it in place. At the same time, rotate the objective lens of the polarizing microscope to switch to the 10x objective lens and align the 10x objective lens with the center of the test circle of SP-T3-1. By rotating the stage and the focusing knob of the polarizing microscope, make the center of the field of view under the microscope basically coincide with the center of the test circle, until the mineral in the test circle of SP-T3-1 is clear under the microscope. Keep the stage still, switch the light source to reflected light, and the optical type to single polarized light. Fine-tune the focus knob to make the mineral in the center of the field of view under the microscope the clearest. Click to take a picture and save the photo as SP-T3-1-(R); keep the stage still, switch the light source to transmitted light, and the optical type to crossed polarized light. Fine-tune the focus to make the mineral in the field of view under the microscope the clearest. Click to take a picture and save the photo as SP-T3-1-(+).

[0058] Next, import the SP-T3-1-(R) and SP-T3-1-(+) images into CorelDRAW or PowerPoint. Referring to the boundary between quartz and other minerals in the crossed-polarized SP-T3-1-(+) image, design 10 test points for laser ablation inductively coupled plasma mass spectrometry (ICP-MS) on the SP-T3-1-(R) image, arranged in an approximate "×" shape. Perform the same operation on SP-T3-2-(R) and SP-T3-3-(R) images to obtain the corresponding test point design and a map showing the location of the designed test points.

[0059] The fourth step involved transferring the SP-T3 sample to a cleanroom environment and placing it in the sample chamber for LA-ICP-MS analysis. The testing instruments were a GeoLasHD 193nm laser ablation system and an Agilent 7900ICP-MS inductively coupled plasma mass spectrometer, with the laser energy set to 9 J / cm². 2The laser frequency was 6Hz, and the laser beam diameter was 44μm. According to the test point map, the laser was aimed at the designed points for analysis and testing. Before starting the analysis of the SP-T3 design points, a set of standard samples (NISTRAM 610, NISTRAM 612 and NISTRAM 614) were analyzed first. Then, a set of standard samples was analyzed every 10 test points before starting the test points of SP-T3. After testing all the design points, another set of standard samples was tested for monitoring. The test cycle for each point was 90 seconds, of which the first 20 seconds were for preparing the test points, and the laser ablation was started for 20 seconds, lasting for 40 seconds. Throughout the process, helium gas was continuously flushed, and ICP-MS continuously received and recorded the count values ​​of elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U). The first 20 seconds are the background integration interval, and 25 of the remaining 40 seconds are selected as the test integration interval.

[0060] The fifth step involved three analytical test circles for sample SP-T3, testing a total of 28 test points and 12 standard samples. The signal files of the test point and standard sample point data were processed using ICPMSDataCal 11.0 software. The elemental content was calculated using the multiple external standard, no internal standard method, also known as the total normalization method. Si from the NISTRAM 610 standard was selected as the normalization element to eliminate the influence of laser ablation amount variation on sensitivity drift.

[0061] Step 6: The ICPMSDataCal 11.0 software SP-T3 and standard sample processing are used to obtain results and output a report. If the element values ​​(Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U) of the standard samples (NISTRAM 610, NISTRAM 612, and NISTRAM 614) in the report are consistent with the known standard values ​​within the error range, then the test values ​​of the 19 points tested by SP-T3 are valid.

[0062] Step 7: Further processing of the data from the 28 points of the SP-T3 test. The contents of B and P elements were corrected by dividing by 100, and Ca was corrected by dividing by 10. The total impurity element content of this batch of natural quartz mineral samples was obtained as 24.93 ± 12.74 μg / g. Specific elemental test results are shown in Table 2 (SP-T3). Example 3: The steps of the method for determining the total impurity element content of natural high-purity quartz minerals provided by this invention are as follows:

[0063] The first step involved selecting a massive quartz rock sample (YD) of grade 4N8 from India. On this massive rock sample, a line segment was drawn centered on the selected quartz mineral. Three rectangular rock sections were then cut from this line using a cutting machine. After smoothing the sections, Canadian resin was applied to glass slides. The samples on the slides were then polished to create thin sections of 25μm, 75μm, and 140μm thickness without coverslips. These thin sections were designated YD-T1, YD-T2, and YD-T3.

[0064] The second step involved first using a polarizing microscope to identify the rock and mineral composition and observe the petrographic features of fluid inclusions on the YD-T1 and YD-T3 thin sections. Then, combined with electron probe microanalysis (EMPA) quantitative analysis of the YD-T2 thin section (probe section), the distribution characteristics of the quartz minerals on the thin section and the nature of any associated minerals were determined. Furthermore, the petrographic features of the fluid inclusions in the quartz minerals were used to determine whether LA-ICP-MS analysis of YD was necessary. Based on the first two steps, three test circles for the quartz minerals were drawn on the YD-T3 thin section (laser section) using a fine (approximately 0.5 mm) oil-based pen. The numbers 1, 2, and 3 were written next to these three test circles, assigning them one-to-one correspondences: YD-T3-1, YD-T3-2, and YD-T3-3, and recorded in a notebook.

[0065] Then place the YD-T3 on the stage of the polarizing microscope and fix it in place. At the same time, rotate the objective lens of the polarizing microscope to switch to the 10x objective lens and align the 10x objective lens with the center of the test circle of YD-T3-1. By rotating the stage and the focusing knob of the polarizing microscope, make the center of the field of view under the microscope basically coincide with the center of the test circle, until the mineral in the test circle of YD-T3-1 is clear under the microscope. Keep the stage still, switch the light source to reflected light, and the optical type to single polarized light. Fine-tune the focus knob to make the mineral in the center of the field of view under the microscope the clearest. Click to take a picture and save the photo as YD-T3-1-(R); keep the stage still, switch the light source to transmitted light, and the optical type to crossed polarized light. Fine-tune the focus to make the mineral in the field of view under the microscope the clearest. Click to take a picture and save the photo as YD-T3-1-(+).

[0066] Next, import the YD-T3-1-(R) and YD-T3-1-(+) images into a CorelDRAW or PowerPoint presentation. Referring to the boundary between quartz and other minerals in the orthogonally polarized YD-T3-1-(+) image, design eight test points for laser ablation inductively coupled plasma mass spectrometry (ICP-MS) on the YD-T3-1-(R) image, arranged in an approximate cross shape. Perform the same operation on YD-T3-2-(R) and YD-T3-3-(R) images to obtain the corresponding test point design and a map showing the location of the designed test points.

[0067] The fourth step involved transferring the YD-T3 sample to a cleanroom environment and placing it in the sample chamber for LA-ICP-MS analysis. The testing instruments were a GeoLasHD 193nm laser ablation system and an Agilent 7900ICP-MS inductively coupled plasma mass spectrometer, with the laser energy set to 7 J / cm². 2 The laser frequency was 2Hz, and the laser beam diameter was 44μm. According to the test point map, the laser was aimed at the designed points for analysis and testing. Before starting the test analysis of the YD-T3 design points, a set of standard samples (NISTRAM 610, NISTRAM 612 and NISTRAM 614) were analyzed first. Then, a set of standard samples was analyzed every 10 test points before starting the test of the subsequent YD-T3 test points. After testing all the design points, another set of standard samples was tested for monitoring. The test cycle for each point was 90 seconds, of which the first 20 seconds were for preparing the test point, and the laser ablation was started for 20 seconds, lasting for 40 seconds. Throughout the process, helium gas was continuously flushed, and ICP-MS continuously received and recorded the count values ​​of elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U). The first 20 seconds are the background integration interval, and 25 of the remaining 40 seconds are selected as the test integration interval.

[0068] The fifth step involved three analytical test circles for sample YD-T3, testing a total of 20 test points and 9 standard samples. The signal files of the test point and standard sample point data were processed using ICPMSDataCal 11.0 software. The elemental content was calculated using the multiple external standard, no internal standard method, i.e., the total normalization method. Si from the NISTRAM 610 standard was selected as the normalization element to eliminate the influence of laser ablation amount variation on sensitivity drift.

[0069] Step 6: The ICPMSDataCal 11.0 software processes YD-T3 and standard samples to obtain results and outputs a report. If the elemental values ​​(Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U) of the standard samples (NISTRAM 610, NISTRAM 612, and NISTRAM 614) in the report are consistent with the known standard values ​​within the error range, then the test values ​​of the 20 points tested by YD-T3 are valid.

[0070] The seventh step involves further processing the data from the 20 points of the YD-T3 test. The contents of B and P elements are corrected by dividing by 100, and Ca is corrected by dividing by 10. The total amount of impurity elements in this batch of natural quartz mineral samples is 18.42±1.85μg / g. The specific element test results are shown in Table 2 of YD-T3.

Claims

1. A method for determining the total amount of impurity elements in natural high-purity quartz minerals, characterized in that... The measurement steps are as follows: S1. Locate and slice the rock specimens to prepare 3 single-sided polished thin slices with thicknesses of T1 = 30 ± 5 μm, T2 = 80 ± 5 μm, and T3 = 150 ± 10 μm respectively. S2. First, use a polarized light microscope to conduct petrographic identification and fluid inclusion petrographic observation on the T1 thin slice. Then, combine with the electron microprobe (EMPA) quantitative analysis of the T2 thin slice, which is the probe slice. Next, circle the area where the quartz mineral is located on the T3 thin slice, which is the laser slice, and take a photo of the laser slice. S3. Design test points on the reflected light photo obtained by taking a photo of the field of view circled on the T3 thin slice for testing on a laser ablation inductively coupled plasma mass spectrometer. With the center of the quartz mineral in the photo as the center, arrange equally spaced measurement points with an interval of 88 - 200 μm symmetrically towards the edge of the quartz mineral. Design the radius of the measurement points to be 44 μm, the number of designed measurement points to be 5 - 12, and the designed measurement points to evenly cover the quartz mineral particles in the photo. S4. Place the T3 thin slice into the sample chamber of the laser ablation inductively coupled plasma mass spectrometer to carry out the testing work. S5. Process the LA-ICP-MS test data of the quartz mineral and output a report. S6. Further organize the content of trace elements in the output report, where the content of B and P elements is corrected by dividing by 100, and the content of Ca is corrected by dividing by 10. S7. Calculate the total amount of thirteen elements in GB / T 32649-2016 《High-purity quartz sand for photovoltaic use》 or the total amount of fifteen elements in IOTA (μg / g) for the corrected content data respectively to determine the total amount of impurity elements in the quartz mineral.

2. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: Regarding the circling of the area where the quartz mineral is located on the T3 thin slice, which is the laser slice, and taking a photo of the laser slice in S2, the requirements for taking the photo are that the objective lens of the polarized light microscope is 10 times, and one reflected light photo and one orthogonal polarized light photo of the same field of view are taken respectively.

3. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: The designed distribution pattern of the measurement points in S3 is in the shape of "one", "person" or "Y", "ten" or "×".

4. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: The test instrument in S4 is a GeoLasHD 193nm laser ablation system and an Agilent 7900 ICP-MS inductively coupled plasma mass spectrometer. The laser energy is 9 ± 2 J / cm2, the laser frequency is 4 ± 2 Hz, and the laser beam spot diameter is 44 μm.

5. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: For the processing of LA-ICP-MS test data in S5, the software ICPMSDataCal 11.0 is used, and the glass standard substance NIST RAM 610 is used as an external standard to correct trace elements.

6. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: The aforementioned polarizing microscope + electron probe method is a method for observing and identifying quartz minerals and their associated minerals. Using a polarizing microscope with single-polarized, crossed, and reflected light, T1 thin sections are observed at magnifications of 25 to 500x by switching between different objective lenses. Based on optical mineralogical characteristics, the characteristics of quartz minerals are determined, and the types of associated minerals are identified. The structure and generational relationship of quartz and its associated minerals are further determined. The T3 probe section is then used to observe the melting and fluid inclusion characteristics of quartz minerals at magnifications of 25 to 500x. The distribution characteristics of quartz mineral inclusions are qualitatively determined. If there are many fluid inclusions in natural quartz minerals, and the spacing between diffusely distributed inclusions is less than 100 μm and small (1 to 10 μm), then further LA-ICP-MS analysis is not required.

7. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 5, characterized in that: The minerals associated with quartz minerals in T2 sections were identified by electron probe microanalysis, and the elemental content of the minerals was quantitatively determined.

8. The method for determining the total amount of impurity elements in natural high-purity quartz minerals according to claim 1, characterized in that: The standard sample used for the S4 determination is NISTRAM 610, while NISTRAM 612 and NISTRAM 614 are used as monitoring samples. The determination operation of the fifth step is as follows: the standard and the sample are measured sequentially. Before testing the sample, a set of standard samples (NISTRAM 610, NISTRAM 612 and NISTRAM 614) are tested first. After analyzing 10 test points, another set of standard samples is tested before starting the subsequent sample point analysis test. The test cycle for each point is 90 seconds, of which the first 20 seconds are for preparing the test point, and the laser ablation is initiated for 20 seconds, lasting for 40 seconds. Throughout the process, helium gas is continuously flushed, and ICP-MS continuously receives and records the count values ​​of elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Rb, Zr, Sn, Ba, W, Tl, Bi, U and Si). The first 20 seconds were used as the background integration interval, and 25 seconds were selected as the test integration interval within the next 40 seconds. The ICP-MS counting signal file was processed using ICPMSDataCal 11.0 software. The elemental content was calculated using the multiple external standard, no internal standard method, i.e., the total normalization method. Si from the NISTRAM 610 standard was selected as the normalization element to eliminate the influence of laser ablation variation on sensitivity drift. The measured content values ​​of the above elements were then exported, with some elements corrected by multiples. The final result is the analytical test result.

Images