Efficient preparation method of rare earth niobium polymetallic ore standard substance

Abstract

The invention provides an efficient preparation method of a rare earth niobium polymetallic ore standard substance, belongs to the technical field of preparation of standard substances for geological mineral detection, and aims to solve the problems that the existing three-rare-earth mineral standard substance is few in variety, concentrated in numerical value distribution and difficult to adapt to newly added 16 element assessment. The method comprises the following steps: selecting rare-earth niobium polymetallic ore of the foregi nationflag grey stone mountain in the Inner Mongolia as a candidate, and naturally airing, crushing, drying, finely crushing and uniformly mixing and processing the rare-earth niobium polymetallic ore; an exclusive analysis method is established for 21 elements, uniformity is evaluated through a single factor variance analysis method, stability is evaluated through a regression curve method and t test, a characteristic value and uncertainty are determined through cooperation of a multi-qualification laboratory and a constant value, and the rare earth niobium polymetallic ore component analysis standard substance is prepared. The standard substance can realize detection result value traceability, guarantee the detection accuracy, meet a new round of geological prospecting detection requirements, and promote laboratory transformation and industry technology improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of standard substance preparation for geological mineral detection, in particular to a high-efficiency preparation method of rare earth niobium polymetallic ore standard substance. BACKGROUND

[0002] Three-rare mineral resources refer to rare earth, rare and rare mineral resources, and the safe supply of three-rare mineral resources is directly related to the development of China's strategic emerging industry. In recent years, China has made progress in the field of three-rare mineral prospecting, such as the project team in 2023 discovered a fluorocarbon cerium ore-fluorite-barite-calcite vein with high grade and large thickness in the periphery of the super-large rare earth ore deposit in Maoniang, Ejin Banner, Sichuan Province, which provides resource guarantee for industrial development, but key rare metals (lithium, niobium, tantalum) still rely on imports, and it is urgent to improve the development and utilization level of three-rare mineral resources through comprehensive research.

[0003] The current country is promoting a new round of geological prospecting action, and three-rare mineral detection work is fully carried out, but the existing three-rare mineral standard substance has obvious shortcomings: the type is less and the numerical distribution is concentrated, which cannot meet the diversified detection demand; at the same time, the new 16-element examination is added in "China Geological Survey Bureau Geochemical Survey Project Sample Analysis Quality Monitoring Management Requirements", and the existing standard substance is difficult to cover the examination range. Under this background, the development of rare earth niobium polymetallic ore component analysis standard substance has become a key requirement to support three-rare mineral detection work and help new round of prospecting breakthrough strategic action.

[0004] Therefore, a high-efficiency preparation method of rare earth niobium polymetallic ore standard substance is proposed. SUMMARY

[0005] The present application provides a high-efficiency preparation method of rare earth niobium polymetallic ore standard substance to solve the problems in the background art.

[0006] The specific technical solutions are as follows: A high-efficiency preparation method of rare earth niobium polymetallic ore standard substance, comprising the following steps: (1) Candidate selection: selecting the rare earth niobium polymetallic ore in Huishishan, Ejin Banner, Inner Mongolia as the standard substance candidate; (2) Candidate processing and preparation: placing the candidate in a clean and ventilated environment for natural drying, crushing the dried candidate by using a jaw crusher, drying the crushed material in a drying equipment, finely crushing the dried material by using a high-aluminum ball mill, and finally uniformly mixing the finely crushed material; (3) Analytical method confirmation: corresponding determination methods were established for rare earth elements, niobium, tantalum, hafnium, and cesium indium respectively; rare earth elements were determined by alkaline fusion precipitation combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry, niobium, tantalum, and hafnium were determined by closed acid dissolution combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry, and cesium indium were determined by closed acid dissolution combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry or tetraacid decomposition combined with inductively coupled plasma atomic emission spectrometry; (4) Uniformity assessment: The mixed material in step (2) is divided into the smallest packages. Under repeatability test conditions, the material in each smallest package is measured three times in different orders using an inductively coupled plasma atomic emission spectrometer. The average value is taken as the test result. The uniformity of the material is judged by one-way ANOVA. (5) Stability assessment: Long-term stability test and short-term stability test were conducted on the repackaged materials, and the trend analysis of the test results was performed using regression curve method and t test; (6) Determination of characteristic values: Multiple laboratories jointly conduct collaborative determination of material characteristic values ​​using a unified measurement method, and use the arithmetic mean as the standard characteristic value of the material; (7) Determination of characteristic value and uncertainty: Based on the measurement results of step (6), calculate and determine the characteristic value and corresponding uncertainty of the material, and finally obtain the rare earth niobium polymetallic mineral standard material.

[0007] This solution covers the complete preparation process of rare earth niobium polymetallic mineral standard materials, from candidate selection to final product acquisition. By selectively choosing mineral samples from specific mining areas as candidates, it lays the foundation for the subsequent preparation of standard materials adapted to actual testing needs. Specific determination methods are established for different elements, reducing detection interference and improving the accuracy of element determination. Combined with homogeneity assessment, stability evaluation, and multi-laboratory collaborative value determination, it effectively controls the homogeneity of material composition and the stability of characteristic values. The final prepared standard materials enable traceability of rare earth niobium polymetallic mineral resource testing results, solving the problems of limited types and concentrated numerical distribution of existing rare earth mineral standard materials, ensuring accurate and reliable test results, and supporting the development of rare earth mineral testing.

[0008] The above-mentioned efficient preparation method of rare earth niobium polymetallic ore standard material, in step (1), before selecting rare earth niobium polymetallic ore from Huishishan, Ejin Banner, Inner Mongolia as a candidate, is first screened based on the compatibility of the rare earth niobium polymetallic ore testing projects undertaken by the laboratory to ensure that the composition of the candidate matches the requirements of the testing projects.

[0009] This approach adds a screening step based on the compatibility of the candidate material with the laboratory's existing testing items during the candidate material selection stage. This ensures that the composition of the selected rare earth niobium polymetallic ore candidate material from Huishishan, Ejin Banner, Inner Mongolia matches the actual testing needs of the laboratory. It avoids the inability of the prepared standard materials to be effectively used in the testing work due to the incompatibility between the candidate material and the testing items, thereby improving the practicality of the standard materials, reducing unnecessary candidate material preparation costs and time waste, and ensuring that the subsequent preparation process is carried out around the actual testing needs.

[0010] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, in step (2), the drying temperature of the drying equipment is controlled at 40-60℃ and the drying time is 8-12h; the fine crushing treatment of the high alumina ball mill makes the particle size of the material reach 200-300 mesh; the mixing treatment is carried out by a three-dimensional mixer, the mixing speed is 20-30r / min and the mixing time is 4-6h.

[0011] This scheme clarifies the key parameter control methods for drying, crushing, and mixing during the candidate material processing and preparation. By controlling the drying temperature and time, it can ensure that the material is fully and uniformly dried, avoiding the impact of residual moisture on the stability of the material composition. Crushing the material to a specific particle size can increase the specific surface area of ​​the material, which facilitates the full dissolution and reaction of elements in subsequent detection processes. Using a three-dimensional mixer to mix according to specific parameters can ensure that the material composition is uniformly distributed throughout the entire range, providing a guarantee for passing the subsequent uniformity assessment and reducing the problem of uneven material composition caused by improper processing parameters.

[0012] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, wherein in step (3), the method for determining rare earth elements is as follows: the material is mixed with sodium hydroxide at a mass ratio of 1:3-1:5 and then subjected to alkaline melting treatment. The molten product is dissolved in hydrochloric acid, and ammonium chloride solution is added for precipitation. The precipitate is washed and dissolved in nitric acid, and then separated by cation exchange resin. The content of rare earth elements in the eluent after separation is determined by inductively coupled plasma atomic emission spectrometry / mass spectrometry.

[0013] This scheme refines the specific operational steps for rare earth element determination. By controlling the alkaline fusion ratio of the material and sodium hydroxide, effective melting of rare earth elements can be achieved. Subsequent steps such as hydrochloric acid dissolution, ammonium chloride precipitation, and cation exchange resin separation can effectively separate rare earth elements from other impurities in the material, reducing the interference of impurities on the rare earth element detection results, improving the accuracy of rare earth element content determination, solving the problem of rare earth element detection errors caused by impurity interference, and ensuring the reliability of rare earth element determination results.

[0014] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, in step (3), the niobium-tantalum-hafnium sealing acid dissolution treatment adopts a nitric acid-hydrofluoric acid mixed acid system, wherein the volume ratio of nitric acid to hydrofluoric acid is 3:1-5:1, the sealing dissolution temperature is 180-200℃, the dissolution time is 4-6h, after the dissolution is completed, boric acid solution is added to eliminate fluoride ion interference, and then the niobium-tantalum-hafnium content is determined by inductively coupled plasma atomic emission spectrometry / mass spectrometry.

[0015] This scheme clarifies the closed acid dissolution system and interference elimination method for the determination of niobium, tantalum, and hafnium. The nitric acid-hydrofluoric acid mixed acid system can fully dissolve sparingly soluble elements such as niobium, tantalum, and hafnium, avoiding low detection results due to insufficient dissolution. The addition of boric acid solution eliminates fluoride ion interference, preventing fluoride ions from reacting with the detection instrument components or affecting the ion signal during the detection process, ensuring accurate determination results of niobium, tantalum, and hafnium content, solving the problems of insufficient dissolution of sparingly soluble elements and fluoride ion interference, and improving the reliability of niobium, tantalum, and hafnium determination.

[0016] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, wherein in step (4), when evaluating the uniformity, no less than 15 samples are randomly selected from the smallest package after dispensing, and the sampling amount of each sample is 0.1-0.2g; in the one-way ANOVA method, if the calculated F value is less than the corresponding critical F value, the material uniformity is determined to be qualified.

[0017] This scheme standardizes the sampling method and judgment criteria for uniformity assessment. Randomly selecting no less than a specific number of samples and controlling the sampling amount can comprehensively cover the entire range of materials and avoid uniformity assessment bias caused by partial sampling. By calculating the F value through one-way ANOVA and comparing it with the critical F value, the uniformity of materials can be quantitatively judged, ensuring that only materials with uniformity that meet the requirements enter the subsequent process. This ensures that the test results of samples taken from different parts are consistent during the use of the final standard material, avoiding differences in test results caused by material inhomogeneity.

[0018] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, in step (5), the long-term stability test cycle is 12 months, and the material characteristic value is measured once every 3 months; the short-term stability test is carried out under three temperature conditions of -20℃, 25℃ and 40℃, the test duration is 48h, and the material characteristic value is measured once every 12h.

[0019] This scheme sets out the cycle and temperature conditions for stability testing. Long-term stability testing, conducted periodically over 12 months, examines the changes in material properties during long-term storage. Short-term stability testing, performed at different temperatures, assesses the stability of materials under various environmental temperatures, such as during transportation and temporary storage. Trend analysis determines the conditions and validity period for material property value stability, ensuring that the property values ​​of the standard substance do not change significantly during storage and use, thus avoiding inaccurate test results due to stability issues.

[0020] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, in step (6), the number of laboratories participating in the collaborative determination is no less than 5, and all laboratories have CMA metrological certification qualifications; the unified determination method is the combination of inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry, in which low-content elements are determined by inductively coupled plasma mass spectrometry, and high-content elements are determined by inductively coupled plasma atomic emission spectrometry.

[0021] This plan clarifies the laboratory qualification requirements and element determination methods for collaborative testing. Selecting laboratories with CMA metrological accreditation ensures that participating laboratories have qualified testing capabilities, reducing deviations in test results caused by insufficient laboratory testing capabilities. The plan employs inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) for elements with high and low content respectively, accommodating the testing needs of elements with different content levels, improving the accuracy of element determination, ensuring reliable collaborative testing results, and providing accurate data support for determining characteristic values.

[0022] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, wherein in step (2), the crushing chamber lining of the jaw crusher, the inner liner of the drying equipment and the grinding chamber of the high alumina ball mill are all treated with polytetrafluoroethylene coating; the alumina purity of the grinding balls used in the high alumina ball mill is ≥99.5%, so as to avoid the introduction of impurity elements during the grinding process.

[0023] This scheme standardizes the materials of processing equipment components and the purity of grinding balls. The polytetrafluoroethylene coating can prevent the equipment's own material from dissolving or falling into the material during the crushing, drying, and grinding processes, thus preventing the material from being contaminated by impurities. High-purity grinding balls can reduce the impurity elements introduced by the grinding balls during the grinding process, ensuring the authenticity of the material composition, avoiding the influence of foreign impurities on subsequent element detection and characteristic value determination, and ensuring the accuracy of the final standard substance composition.

[0024] The above-mentioned efficient preparation method of rare earth niobium polymetallic mineral standard material, wherein the final rare earth niobium polymetallic mineral standard material covers 21 elements including scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, niobium, cesium, hafnium, indium, and tantalum, and the relative standard deviation of the characteristic value of each element is ≤5%.

[0025] This scheme clarifies the elemental coverage and characteristic value deviation control requirements of the final standard reference material. Covering 21 elements can meet the needs of simultaneous multi-element detection in rare earth mineral testing, and is particularly compatible with the assessment requirements of 16 elements in the "Quality Monitoring and Management Requirements for Sample Analysis of Geochemical Survey Projects of China Geological Survey", solving the problem of insufficient elemental coverage in existing standard reference materials. Controlling the relative standard deviation of the characteristic values ​​of each element can ensure the stability of the characteristic values ​​of the standard reference material, improve the repeatability and accuracy of the test results, and provide comprehensive and reliable standard support for multi-element detection of rare earth and niobium polymetallic mineral resources.

[0026] This invention also proposes a key equation—the "Uniformity-Stability Composite Index" (U-SIndex)—which is used to quantitatively evaluate the overall quality of standard materials and optimize the preparation process.

[0027] Specifically, after steps (4) and (5), a step of calculating the homogeneity-stability composite index (U-SIndex) is included. This index is used to comprehensively evaluate the homogeneity and stability of the standard material, and its equation is defined as: ; in: F is the F value calculated by one-way ANOVA in the assessment of uniformity. It is obtained from one-way ANOVA and reflects the ratio of variance between groups to variance within groups. F c The critical F value corresponding to the uniformity assessment is obtained from the F distribution table and depends on the degrees of freedom (df1, df2). b is the slope of the regression curve in the long-term stability test, which represents the rate of change of the characteristic value over time; b0 is the allowable slope threshold, with a value of 0.001 μg / g / month; RSDRSD is the relative standard deviation (%) of characteristic values ​​in collaborative determinations, calculated from collaborative determination data, and represents the degree of inter-laboratory variability. The value of U-SIndex ranges from 0 to 1. The closer the value is to 1, the better the overall performance of the standard substance in terms of homogeneity and stability. When U-SIndex ≥ 0.9, the standard substance is judged to be of qualified quality.

[0028] The derivation of the equation: 1. Derivation of the homogeneity component: One-way ANOVA is used in homogeneity assessment. The F-value represents the ratio of between-group variance to within-group variance. When the F-value is less than the critical F-value (F... <F c When the homogeneity is within acceptable limits, a ratio is used to quantify the contribution to homogeneity. The uniformity is excellent when the F value is close to 0, but for normalization, we use... As a homogeneity component, this value increases as the F value decreases, ranging from 0.5 to 1.

[0029] 2. Derivation of Stability Components: The stability assessment uses the regression curve method, where the slope 'b' represents the trend of the characteristic value over time. The smaller |b| is, the better the stability. An exponential decay function is used. As a stability component, b0 is the slope threshold, set to 0.001 μg / g / month based on experimental data. When |b| is close to 0, this component is close to 1.

[0030] 3. Derivation of Collaborative Assignment Components: The relative standard deviation (RSD) of characteristic values ​​in collaborative assignments represents the consistency between laboratories. A smaller RSD indicates better consistency. (Using...) As a cooperative constant component, this component is 1 when RSD is 0.

[0031] 4. Comprehensive index: The U-SIndex is obtained by multiplying the three components together, which comprehensively reflects the uniformity, stability and consistency of cooperative values.

[0032] Example: Taking the data from Example 1 as an example: Uniformity assessment: F=1.5, F_c=2.2, uniformity component .

[0033] Long-term stability: Regression slope b = 0.00083 μg / g / month (based on neodymium element data), stability component .

[0034] Collaborative setpoint: RSD = 1.2%, Collaborative setpoint component .

[0035] U-SIndex=0.595×0.436×0.988=0.256.

[0036] Since this value is below 0.9, it indicates that the preparation process needs to be optimized. The U-SIndex should be recalculated by adjusting processing parameters (such as increasing mixing time or temperature) until the required level is achieved.

[0037] Technical effects: 1. Comprehensive quality assessment: U-SIndex provides a single index that comprehensively quantifies the homogeneity, stability, and consistency of standard materials, avoiding the limitations of single assessments.

[0038] 2. Process optimization: By calculating U-SIndex, weak links in the preparation process are identified, and parameter adjustments (such as mixing time and temperature control) are guided to improve preparation efficiency and quality.

[0039] 3. Reduce testing costs: By predicting and optimizing, unnecessary long-term stability testing and repeated experiments are reduced, saving time and resources.

[0040] 4. Improve reliability: Ensure that the characteristic values ​​of standard substances are stable during storage and use, and enhance the traceability and comparability of test results.

[0041] Working principle and process: 1. Data input: Obtain F-value, F_c, regression slope b, and RSD from the homogeneity assessment, stability evaluation, and collaborative determination steps.

[0042] 2. Component Calculation: Calculate the uniformity component, stability component, and cooperative constant component respectively.

[0043] 3. Exponent Calculation: Multiply the three components together to obtain U-SIndex.

[0044] 4. Quality judgment: Compare U-SIndex with the threshold (0.9) to determine whether the standard substance is qualified.

[0045] 5. Feedback optimization: If the index is below the threshold, adjust the processing parameters (such as particle size and mixing conditions), re-process and evaluate until the index reaches the target.

[0046] The present invention has the following beneficial effects: 1. Addressing the shortcomings of existing standard reference materials and meeting testing needs: By developing a rare earth niobium polymetallic mineral standard reference material covering 21 elements (including 16 newly added assessment elements in the "Requirements for Quality Monitoring and Management of Sample Analysis of Geochemical Survey Projects of China Geological Survey"), the existing rare earth mineral standard reference materials have been improved due to their limited variety, concentrated numerical distribution, and insufficient element coverage. This material is suitable for the diverse testing scenarios in the current round of geological prospecting and provides comprehensive standard support for rare earth mineral testing.

[0047] 2. Ensure accurate and reliable test results and achieve metrological traceability: The project employs rigorous candidate screening (to ensure the representativeness of mineral samples), meticulous processing and preparation (to ensure uniform composition), scientific homogeneity and stability assessment (to ensure stable characteristic values), and authoritative multi-laboratory collaborative value determination (to ensure accurate characteristic values ​​and metrological traceability). This ensures that the prepared standard substances can provide reliable metrological traceability for the test results of rare earth niobium polymetallic minerals, reduce the deviation of results between different laboratories and different test batches, and ensure that the test data are comparable and reliable.

[0048] 3. Promoting laboratory transformation and industry technology upgrading: Based on the research and development results of standard materials, the laboratory can further develop other mineral standard materials, optimize the detection and data processing process, enhance detection technology capabilities and industry influence, and realize the transformation and upgrading of the laboratory; at the same time, the multi-laboratory collaborative value determination process promotes technical exchanges within the industry, unifies the detection methods and operating procedures for rare earth niobium polymetallic minerals, and helps to improve the technical level of the entire rare earth minerals testing industry.

[0049] 4. Economic and social benefits: From an economic perspective, the promotion and application of standard materials can save laboratory personnel and testing costs, while creating new profit growth points for laboratories through the sale of standard materials (such as the expected output value of the document); from a social perspective, standard materials can be transformed into social influence after being reviewed, and laboratories can rely on the results to apply for science and technology awards, key laboratories, etc., enhance their brand awareness, and at the same time provide technical support for the efficient development and supervision of rare mineral resources in my country, and help the development of strategic emerging industries. Attached Figure Description

[0050] Figure 1 A flowchart illustrating an efficient preparation method for rare earth niobium polymetallic mineral standard materials provided in this embodiment of the invention; Figure 2 This is a graph showing the changes in processing and preparation data for Example 1; Figure 3 This is a long-term stability monitoring graph for Example 1; Figure 4 This is a comparison chart of element recovery rates in Example 2; Figure 5 The image shows the laboratory lanthanum determination results for Example 3. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0052] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0053] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0054] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] Reference Figures 1-5 ,in: Figure 2 The changes in key parameters during the three stages of natural air drying → oven drying → fine crushing are shown: the moisture content decreases from 1.5% to 0.4%, meeting the process requirement of ≤0.5%; the 250 mesh passing rate reaches 98.5%, which meets the fine crushing process standard; the curve trend intuitively reflects the improvement effect of the processing flow on the material properties; Figure 3 The study demonstrates the trend of neodymium element property values ​​over 12 months: the initial value was 1.18 μg / g, which stabilized at 1.17 μg / g after 12 months; the monthly fluctuation range was ≤0.01 μg / g, far below the allowable error of ±5%; and the stability of the sample under long-term storage conditions was verified. Figure 4The diagram shows the recovery range and peak values ​​of niobium, tantalum, and hafnium using stacked bar charts: niobium recovery 95%-101%, tantalum 94%-100%, hafnium 95%-102%; the optimized closed acid dissolution system improves the recovery of sparingly soluble elements by 5-8 percentage points; the red dashed lines indicate the standard value ranges for easy comparison. Figure 5 The distribution of lanthanum determination values ​​from seven laboratories is shown: data points are densely distributed in the range of 5.20-5.25 μg / g, with an average of 5.22 μg / g; the standard value of 5.22 μg / g is marked with a red dashed line, and the deviation is ≤0.8%; this demonstrates the accuracy of collaborative determination and the consistency between laboratories.

[0056] This specific implementation provides the following three specific embodiments: Example 1: Preparation of Basic Standard Materials for Rare Earth Niobium Polymetallic Minerals I. Technical Solution 1. Candidate selection: The rare earth niobium polymetallic ore from Huishishan in Ejin Banner, Inner Mongolia, was selected as the candidate standard material. Before selection, the laboratory had undertaken rare earth niobium polymetallic ore testing projects (covering the determination of rare earth, niobium, tantalum, cesium, indium and other elements) to confirm that the composition of the candidate material was suitable for the testing requirements and that the ore sample was regionally representative.

[0057] 2. Candidate Processing and Preparation: The candidate was placed in a clean and ventilated environment and air-dried naturally for 72 hours to remove surface free moisture. The dried ore sample was coarsely crushed using a jaw crusher (with a PTFE-coated crushing chamber) to a particle size ≤10mm. The coarsely crushed material was then placed in a drying equipment (with a PTFE-coated inner liner) and dried at 50℃ for 10 hours to ensure a material moisture content ≤0.5%. The dried material was then finely crushed using a high-alumina ball mill (with a PTFE-coated grinding chamber and alumina purity ≥99.5% for the grinding balls) to control the particle size to 250 mesh. The finely crushed material was then fed into a three-dimensional mixer and mixed at 25r / min for 5 hours to complete the material pretreatment.

[0058] 3. Analytical method confirmation: 3.1 Rare earth elements (scandium, yttrium, lanthanum, etc., 15 in total): Alkali fusion precipitation-cation exchange resin separation-inductively coupled plasma atomic emission spectrometry / mass spectrometry was used. The pretreated material was mixed with sodium hydroxide at a mass ratio of 1:4 and alkali fused in a muffle furnace at 700℃ for 30 min. The molten product was dissolved in 5% hydrochloric acid, and 10% ammonium chloride solution was added to precipitate impurities. After washing the precipitate, it was dissolved in 2% nitric acid and separated by cation exchange resin (model 001×7). The eluent was used to determine the high content of rare earth elements by ICP-OES and the low content of rare earth elements by ICP-MS.

[0059] 3.2 Niobium, Tantalum, and Hafnium: Closed-loop acid dissolution-inductively coupled plasma mass spectrometry was used. 0.1 g of pretreated material was placed in a polytetrafluoroethylene dissolution vessel, and 5 mL of a nitric acid-hydrofluoric acid mixture (volume ratio 4:1) was added. After sealing, the sample was dissolved in an oven at 190 °C for 5 h. After cooling, 2 mL of 5% boric acid solution was added to eliminate fluoride ion interference. After adjusting the volume, the sample was determined by ICP-MS.

[0060] 3.3 Cesium and Indium: The tetraacid decomposition-inductively coupled plasma mass spectrometry method was used. 0.1 g of pretreated material was taken and 8 mL of a mixed acid mixture of nitric acid, hydrochloric acid, hydrofluoric acid and perchloric acid (volume ratio 3:3:2:1) was added. The mixture was heated at low temperature until it was nearly dry. After removing the perchloric acid, the volume was adjusted with 2% nitric acid and the determination was performed by ICP-MS.

[0061] 4. Uniformity assessment: The mixed material was divided into 1000 smallest packages (50g per package). 15 packages were randomly selected, and 0.2g of each package was sampled. Under repeatability test conditions (same ICP-OES instrument, same operator, same reagent batch), the cerium concentration of each sample was measured 3 times in random order, and the average value was taken as the test result. The between-group variance and within-group variance were calculated using one-way ANOVA to obtain the F-value.

[0062] 5. Stability assessment: 5.1 Long-term stability: Ten smallest packages were selected, and samples were taken at 0, 3, 6, 9, and 12 months to determine the neodymium element characteristic values. The regression curve method was used to analyze the trend of characteristic values ​​over time, and the t-test was used to determine whether there were significant differences.

[0063] 5.2 Short-term stability: Six smallest packages were selected and placed in environments of -20℃, 25℃, and 40℃ respectively. The europium elemental characteristic values ​​were measured at 0, 12, 24, 36, and 48 hours. The trend was analyzed by regression curve method and t test.

[0064] 6. Characteristic value determination and uncertainty assessment: Five laboratories with CMA metrological accreditation collaborated to conduct joint measurements on 21 elements using the unified analytical method determined in step 3; the measurement data from each laboratory were collected, outliers were removed, and the arithmetic mean was calculated as the standard characteristic value for each element; combined with homogeneity and stability test data and collaborative measurement deviations, the expanded uncertainty (coverage factor k=2) of the characteristic value of each element was calculated using the GUM method.

[0065] II. Working Principle 1. Candidate Selection Principle: The rare earth niobium polymetallic mine in Huishishan, Ejin Banner, Inner Mongolia, is a typical rare earth mineral. Its composition covers 21 target elements and has strong compatibility with laboratory testing items. This ensures that the prepared standard substances can directly serve actual testing scenarios and avoid the lack of practicality of standard substances due to deviations in candidate composition.

[0066] 2. Processing and preparation principle: Natural air drying and low-temperature drying can remove free moisture from the material, avoiding the influence of moisture on subsequent element dissolution and detection; jaw crusher + high-alumina ball mill fine crushing can gradually reduce the particle size of the material and increase the specific surface area, providing conditions for the full release of elements during subsequent acid / alkali dissolution; polytetrafluoroethylene coating and high-purity grinding balls can prevent impurities from leaching from the equipment material, avoiding contamination of the material; three-dimensional mixer achieves uniform mixing of materials through multi-directional movement, reducing component segregation.

[0067] 3. Analytical Method Principle: Alkali leaching precipitation can destroy the mineral crystal lattice, releasing rare earth elements and reacting with the alkali to form soluble salts. Cation exchange resin can separate and remove impurity cations such as iron and calcium, reducing interference with ICP-OES / MS detection. Blocking acid dissolution utilizes the strong oxidizing and complexing properties of the nitric acid-hydrofluoric acid mixture to dissolve sparingly soluble elements such as niobium, tantalum, and hafnium. Boric acid forms a stable complex with fluoride ions, eliminating the corrosion and signal interference of fluoride ions on the detection instrument. Tetraacid decomposition can completely destroy the material structure, ensuring the complete retention of volatile elements such as cesium and indium. ICP-OES / MS uses plasma to excite elements to generate characteristic spectra or ion signals, achieving quantitative element determination.

[0068] 4. Uniformity assessment principle: One-way ANOVA compares the variance differences between groups (different packaging) and within groups (multiple measurements of the same packaging). If the variance between groups is not significantly greater than the variance within groups, it indicates that the material is uniformly distributed among the packaging, which can meet the requirement that "any sample of the standard substance represents the whole".

[0069] 5. Stability assessment principle: The regression curve method determines whether there is a significant trend by fitting the characteristic value change curve with time / temperature; the t test determines whether there is a statistically significant change by comparing the difference of characteristic values ​​at different times / temperatures, ensuring that the characteristic values ​​of the standard material are stable during the storage and use period.

[0070] 6. Collaborative determination principle: Multiple laboratories with CMA accreditation use a unified method for determination, which can reduce systematic and random errors of individual laboratories; the arithmetic mean can comprehensively reflect the central tendency of data from various laboratories, and combined with uncertainty assessment, it can comprehensively characterize the reliability of characteristic values, providing a basis for traceability of measurement values.

[0071] III. Experimental Data 1. Processing and preparation data: After natural air drying, the moisture content of the material decreased from the initial 8.2% to 1.5%, and after drying, the moisture content further decreased to 0.4%; after fine crushing, the particle size detection of the material showed that the passing rate of 250 mesh reached 98.5%; after three-dimensional mixing, the relative deviation of the cerium element concentration in different positions of the same batch of material was 1.2%.

[0072] 2. Analytical method validation data: In the determination of rare earth elements, the spiked recovery rate of lanthanum was 96%-103%, the spiked recovery rate of niobium was 95%-102%, and the spiked recovery rate of cesium was 97%-104%. The method precision test (six parallel determinations of the same sample) showed that the relative standard deviation of all elements was ≤3%.

[0073] 3. Uniformity assessment data: The concentration of cerium in 15 randomly selected packages ranged from 1.20 to 1.23 μg / g. The within-group variance was calculated. =0.0002, between-group variance =0.0003, F= / =1.5; find the critical value from the F-distribution table. (14,30)=2.2, F<critical value, the material uniformity is deemed acceptable.

[0074] 4. Stability assessment data: In the long-term stability test, the neodymium element characteristic value changed from 1.18 μg / g to 1.17 μg / g within 12 months, as shown in the regression curve. =0.91, t=0.7< (4) = 2.78, with no significant change; in the short-term stability test, the characteristic value of europium fluctuated within 48 hours at 40℃, ranging from 0.85 to 0.86 μg / g, with a relative deviation of ≤1.2%, and t = 0.5 < critical value, with no significant change.

[0075] 5. Collaborative determination data: The results of niobium determination by 5 laboratories were 0.84, 0.85, 0.86, 0.85 and 0.84 μg / g, respectively, with an arithmetic mean of 0.85 μg / g and a relative standard deviation of 1.2%; the uncertainty assessment yielded an expanded uncertainty U = 0.02 μg / g (k = 2).

[0076] IV. Technical Effects 1. Through a complete process of candidate selection, processing and preparation, analysis and detection, homogeneity and stability assessment, and collaborative value determination, the prepared rare earth niobium polymetallic mineral standard material is ensured to meet the national first-class standard material technical specifications. This enables traceability of the measurement results of rare earth niobium polymetallic mineral resources, solving the problem of limited types and concentrated numerical distribution of existing rare earth mineral standard materials.

[0077] 2. During the processing, anti-pollution measures (PTFE coating, high-purity grinding balls) are adopted to avoid the introduction of foreign impurities. Combined with targeted acid-soluble / alkali-soluble analysis methods, detection interference is reduced, ensuring the accuracy of the determination results of 21 target elements. It can meet the assessment requirements of 16 elements in the "Requirements for Quality Monitoring and Management of Sample Analysis of Geochemical Survey Projects of China Geological Survey".

[0078] 3. The results of the homogeneity and stability tests show that the standard material is evenly distributed in the packaging room and its characteristic values ​​are stable during the storage and use period. This can ensure consistent results when samples are taken and tested in different laboratories at different times, thereby improving the repeatability and reliability of rare mineral testing.

[0079] Example 2: Optimized Example for Determination of Insoluble Elements (Niobium, Tantalum, Hafnium) in Rare Earth Niobium Polymetallic Ore Standard Reference Materials I. Technical Solution 1. Selection and processing of candidate materials: As in Example 1, rare earth niobium polymetallic ore from Huishishan, Ejin Banner, Inner Mongolia was selected and processed by air drying, crushing, baking (55℃, 9h), fine crushing (200 mesh), and mixing (20r / min, 6h).

[0080] 2. Optimization of analytical methods for sparingly soluble elements (niobium, tantalum, hafnium): 2.1 Optimization of the closed acid dissolution system: A mixed acid of nitric acid and hydrofluoric acid was used, and the volume ratio was adjusted to 5:1 (4:1 in Example 1). The dissolution temperature was increased to 200℃ (190℃ in Example 1), and the dissolution time was extended to 6h (5h in Example 1). After the dissolution was completed, 3mL of 8% boric acid solution (5% in Example 1) was added and stirred for 15min to ensure complete complexation of fluoride ions.

[0081] 2.2 Instrument parameter optimization: During ICP-MS measurement, the radio frequency power was adjusted to 1550W (originally 1500W), the sampling depth to 8mm (originally 7mm), and the nebulizer gas flow rate to 1.05L / min (originally 1.0L / min) to reduce the influence of matrix effects on the signals of niobium, tantalum, and hafnium ions.

[0082] 3. Other elemental analysis: The analysis methods for rare earth elements, cesium, and indium are the same as in Example 1.

[0083] 4. Homogeneity and stability assessment: Using niobium, tantalum and hafnium as target elements, 15 packages were sampled for homogeneity assessment, and each sample was measured 3 times; stability assessment was conducted over a long period of 12 months (measured once every 3 months) and over a short period of 40℃ for 48 hours (measured once every 12 hours), using the same method as in Example 1.

[0084] 5. Collaborative determination: Six CMA laboratories were jointly involved, and the optimized closed acid dissolution-ICP-MS method was used to determine niobium, tantalum, and hafnium. The determination methods for other elements were the same as in Example 1. Characteristic values ​​and uncertainties were calculated.

[0085] II. Working Principle 1. Dissolution principle of sparingly soluble elements: Niobium, tantalum, and hafnium exist in minerals as stable oxides, which are difficult to completely dissolve with conventional acids; increasing the nitric acid-hydrofluoric acid ratio (5:1) can enhance the oxidizing and complexing properties of the mixed acid, and hydrofluoric acid can form stable fluorine complexes with niobium, tantalum, and hafnium (e.g., ... , This promotes the dissolution of oxides; increasing the dissolution temperature (200℃) and extending the time (6h) can accelerate the reaction rate and ensure the complete release of sparingly soluble elements; increasing the concentration and amount of boric acid can more fully react with excess fluoride ions to generate... This avoids the reaction of fluoride ions with the ICP-MS atomization chamber and torch tube, and also eliminates the suppression of niobium, tantalum, and hafnium ion signals by fluoride ions.

[0086] 2. Instrument parameter optimization principle: The radio frequency power, sampling depth, and nebulizer gas flow rate of ICP-MS directly affect plasma stability and ionization efficiency; increasing the radio frequency power to 1550W can enhance plasma energy and improve the ionization efficiency of niobium, tantalum, and hafnium; adjusting the sampling depth to 8mm can avoid the low-temperature region at the tail of the plasma and reduce matrix interference; optimizing the nebulizer gas flow rate to 1.05L / min can improve the sample nebulization effect, enhance the ion signal intensity and stability, and reduce the detection limit.

[0087] III. Experimental Data 1. Optimized dissolution efficiency data: Using the same sample, the acid dissolution systems of Example 1 and this example were used to determine the niobium, tantalum, and hafnium. Before optimization, the niobium recovery rate was 88%-92%, the tantalum recovery rate was 85%-90%, and the hafnium recovery rate was 86%-91%. After optimization, the niobium recovery rate was 95%-101%, the tantalum recovery rate was 94%-100%, and the hafnium recovery rate was 95%-102%, and the fluctuation range of the recovery rate was reduced.

[0088] 2. Optimized instrument parameters: After optimization, the detection limits of niobium, tantalum, and hafnium by ICP-MS decreased from 0.005 μg / g, 0.006 μg / g, and 0.005 μg / g to 0.003 μg / g, 0.004 μg / g, and 0.003 μg / g, respectively; the relative standard deviation of method precision (six parallel determinations) decreased from 3.5%-4.2% to 1.8%-2.5%.

[0089] 3. Homogeneity data: The results of niobium element determination in 15 packages were 0.83-0.86 μg / g, with within-group variance... =0.0002, between-group variance =0.0002, F=1.0< (14,30)=2.2, which is uniform and qualified; the uniformity F values ​​of tantalum and hafnium are 1.1 and 1.2 respectively, both of which are less than the critical value.

[0090] 4. Stability data: Over the long term (12 months), the characteristic value of niobium changed from 0.85 μg / g to 0.84 μg / g, with a regression curve R²=0.93 and t=0.6 < critical value; Over the short term (40℃ for 48 hours), the characteristic value of hafnium fluctuated by ≤1.0%, with no significant change.

[0091] 5. Collaborative determination data: The results of tantalum determination by 6 laboratories were 0.52-0.54 μg / g, with an arithmetic mean of 0.53 μg / g, a relative standard deviation of 1.0%, and an expanded uncertainty U=0.01 μg / g (k=2).

[0092] IV. Technical Effects 1. By optimizing the closed acid dissolution system and ICP-MS instrument parameters for sparingly soluble elements niobium, tantalum, and hafnium, the problems of incomplete dissolution and low recovery rate of sparingly soluble elements in conventional acid dissolution methods were solved, improving the accuracy and precision of sparingly soluble element determination and ensuring that the characteristic values ​​of niobium, tantalum, and hafnium in the standard material can truly reflect the actual composition of the mineral sample.

[0093] 2. The optimized analytical method is more stable, with a smaller fluctuation range in recovery rate and a lower detection limit, which can meet the needs of accurate determination of low-content sparingly soluble elements and provide reliable technical support for the detection of low-content key elements (such as hafnium) in rare earth niobium polymetallic ores.

[0094] 3. Based on the homogeneity and stability evaluation results of the optimization method, the uniform distribution of sparingly soluble elements in the standard material between packaging and the stability of characteristic values ​​during storage are further guaranteed, avoiding the overall unqualified standard material due to the measurement deviation of sparingly soluble elements, and improving the overall quality of the standard material.

[0095] Example 3: Multi-laboratory Collaborative Value Determination Example of Rare Earth Niobium Polymetallic Ore Standard Materials I. Technical Solution 1. Selection and processing of candidate materials: As in Example 1, rare earth niobium polymetallic ore from Huishishan, Ejin Banner, Inner Mongolia, was pretreated and then packaged into 1200 smallest packages (50g per package). 30 packages were randomly selected for collaborative value determination.

[0096] 2. Selection of Collaborating Laboratories: Seven laboratories (covering North China, East China, and Northwest China) with CMA metrological certification and experience in testing rare earth niobium polymetallic minerals were selected to ensure that the laboratory testing equipment (ICP-OES, ICP-MS) is metrologically calibrated and that the operators have the relevant testing qualifications.

[0097] 3. Standardized testing methods and quality control: 3.1 Distribute a standardized “Collaborative Determination Operation Manual” to all laboratories, specifying the determination methods for all elements (rare earth elements: alkaline fusion precipitation-cation exchange resin separation-ICP-OES / MS; niobium, tantalum, hafnium: blocked acid dissolution-ICP-MS; cesium, indium: tetraacid decomposition-ICP-MS), and specifying reagent purity (analytical grade or higher), instrument parameters (such as ICP-OES wavelength, ICP-MS mass number), and data recording format.

[0098] 3.2 Provide each laboratory with two standardized quality control samples (rare earth standard materials with known characteristic values). The laboratories are required to measure the quality control samples first, and only after the quality control is qualified (the measured value is within the uncertainty range of the standard value) can the collaborative sample measurement be carried out.

[0099] 4. Sample distribution and data collection: Distribute 3 collaborative sample packages to each of the 7 laboratories. Each sample is required to be measured in parallel 3 times and the raw data should be recorded. Within 15 days after the measurement is completed, each laboratory shall submit a data report (including raw records, instrument calibration certificates, and quality control sample results). The lead laboratory (North China Nonferrous Metals Yanjiao Center Laboratory) will summarize the data.

[0100] 5. Data processing and characteristic value determination: 5.1 Data review: Remove outlier data (using the Grubbs method, significance level α=0.05) to ensure that the remaining data meet statistical requirements.

[0101] 5.2 Characteristic value calculation: For each element data that has passed the review, the arithmetic mean is calculated as the standard characteristic value; the uncertainty is calculated using the analysis of variance method, including the inter-laboratory variance, the intra-laboratory variance, the homogeneity variance, and the stability variance.

[0102] 6. Results Verification: Compare the determined characteristic values ​​with the results measured individually by the lead laboratory. If the deviation is ≤2%, the collaborative determination results are considered reliable.

[0103] II. Working Principle 1. Principles for selecting collaborative laboratories: Selecting laboratories with CMA accreditation ensures that their testing capabilities meet national metrological standards and reduces testing deviations caused by insufficient laboratory qualifications; covering laboratories in different regions avoids systematic errors caused by regional environments (such as reagent batches and instrument models); requiring laboratories to pass quality control sample verification in advance can identify laboratory operational errors or instrument malfunctions in advance, ensuring the validity of collaborative data.

[0104] 2. Standardized Method Principles: Establishing standardized operating instructions can eliminate systematic errors caused by differences in methods among laboratories (such as acid-solution ratio, sample dissolution time, and instrument parameters), enabling all laboratories to obtain data under the same testing conditions and ensuring data comparability; standardizing reagent purity and instrument calibration requirements can reduce random errors caused by reagent impurities and uncalibrated instruments.

[0105] 3. Data processing principle: The Grubbs method can effectively identify outliers in the data (such as extreme values ​​caused by operational errors) and avoid the influence of outliers on the average value; the arithmetic mean can comprehensively reflect the central tendency of data from multiple laboratories and is more representative than data from a single laboratory; uncertainty calculation covers multi-dimensional variance, which can comprehensively characterize the reliability of characteristic values ​​and provide a complete error assessment basis for traceability of measurement values.

[0106] III. Experimental Data 1. Laboratory quality control data: The lanthanum content of the quality control sample (rare earth standard material GBW07605) determined by 7 laboratories was 5.20-5.25 μg / g, while the standard value was 5.22 μg / g. All laboratory measurements were within ±0.03 μg / g of the standard value (uncertainty range), indicating that the quality control was qualified.

[0107] 2. Data Review: Cerium elemental determination data from 7 laboratories (a total of 63 data points) were compiled. The Grubbs statistic G was calculated using the Grubbs method, yielding a result of G=1.8 < 0.05. (63) = 2.3, no abnormal data was removed; the audit results of other element data were consistent, and there were no abnormal values.

[0108] 3. Characteristic value calculation data: 3.1 Cerium: The results from 7 laboratories were 1.20-1.24 μg / g, with an arithmetic mean of 1.22 μg / g; interlaboratory variance = 0.0001, intralaboratory variance = 0.0002, homogeneity variance = 0.0001, stability variance = 0.0001, combined uncertainty = 0.01 μg / g, and expanded uncertainty U = 0.02 μg / g (k = 2).

[0109] 3.2 Tantalum: The arithmetic mean is 0.53 μg / g, and the expanded uncertainty is U = 0.01 μg / g (k = 2). The characteristic values ​​of other elements are similar to the uncertainty calculation results, and the relative standard deviations are all ≤1.5%.

[0110] 4. Verification data: The lead laboratory determined the cerium elemental characteristic value to be 1.21 μg / g, which is 0.8% ≤ 2% different from the collaborative determination result (1.22 μg / g), thus the verification is qualified; the deviations of other elements are all ≤ 1.5%.

[0111] IV. Technical Effects 1. By selecting qualified laboratories in multiple regions to conduct collaborative value determination, and combining unified methods and quality control verification, the systematic and random errors of single-laboratory testing are eliminated, making the characteristic values ​​of standard materials more authoritative and representative. This provides a basis for mutual recognition of test results between different laboratories and helps the international mutual recognition of my country's rare earth niobium polymetallic mineral testing results.

[0112] 2. Rigorous data review and multi-dimensional uncertainty assessment comprehensively characterize the reliability of characteristic values, avoid deviations in characteristic values ​​caused by improper data processing, ensure that standard substances can meet the traceability requirements of metrological values, and provide accurate standard basis for quality control of rare mineral testing.

[0113] 3. The collaborative standardization process promoted technical exchanges among laboratories, standardized the methods and operating procedures for the detection of rare earth niobium polymetallic minerals, helped improve the overall testing level of the industry, and expanded the social influence of the preparation of standard materials, laying the foundation for the subsequent promotion and application of standard materials.

[0114] In summary, the working principle of the efficient preparation method for rare earth niobium polymetallic mineral standard materials provided in this embodiment revolves around "ensuring the representativeness, homogeneity, stability, and metrological traceability of the standard materials," and is specifically applied throughout the entire research and development process: 1. Principle of Candidate Selection: The rare earth niobium polymetallic deposit in Huishishan, Ejin Banner, Inner Mongolia was selected as a candidate. The core reason is that the composition of the ore sample from this mining area is compatible with the rare earth niobium polymetallic ore testing projects undertaken by the laboratory, and covers 21 elements of the target study (rare earth elements such as scandium, yttrium, and lanthanum, as well as rare elements such as niobium, cesium, hafnium, indium, and tantalum). It can represent the characteristics of typical rare earth niobium polymetallic ore in my country, laying the foundation for the subsequent preparation of standard materials that meet the actual testing requirements.

[0115] 2. Processing and Preparation Principle: Through a process of "natural air drying - jaw crusher crushing - drying - high-alumina ball mill fine crushing - mixing," free moisture in the mineral sample is gradually removed, particle size is reduced, and uniform mixing of components is achieved. Natural air drying and drying (controlling moisture content) are to prevent moisture from affecting the accuracy of subsequent elemental analysis; fine crushing to a specific particle size increases the specific surface area of ​​the mineral sample, facilitating the full release of elements during subsequent acid / alkali dissolution; and the mixing process initially ensures uniform distribution of mineral sample components, providing a prerequisite for passing subsequent homogeneity assessment.

[0116] 3. Analytical Method Principles: Specific determination methods are established for different elemental characteristics: For rare earth elements, alkaline fusion precipitation-cation exchange resin separation-inductively coupled plasma atomic emission spectrometry / mass spectrometry is used. Alkaline fusion destroys the mineral lattice, and precipitation and resin separation remove impurities and reduce interference. For niobium, tantalum, and hafnium, closed acid dissolution-inductively coupled plasma atomic emission spectrometry / mass spectrometry is used. The strong oxidizing and complexing properties of the nitric acid-hydrofluoric acid mixture dissolve sparingly soluble elements, and boric acid is added to eliminate fluoride ion interference. For cesium and indium, closed acid dissolution or tetraacid decomposition combined with inductively coupled plasma mass spectrometry is used to ensure complete retention and accurate determination of volatile or low-content elements.

[0117] 4. Homogeneity and Stability Assessment Principles: Homogeneity assessment uses one-way ANOVA. By repeatedly measuring the smallest packaged sample after repackaging, the variances between and within groups are compared to determine whether the sample composition is homogeneous (homogeneity is qualified if the variance between groups is not significantly greater than the variance within groups), ensuring that any sample of the standard substance can represent the whole. Stability assessment uses regression curve method and t-test. By monitoring the characteristic values ​​over a long period (12-month cycle) and a short period (different temperature conditions), the trend of characteristic values ​​changing with time and temperature is analyzed to determine whether there are significant changes, ensuring that the characteristics of the standard substance are stable during storage, transportation and use.

[0118] 5. Collaborative Value Determination Principle: This principle involves collaborating with multiple qualified laboratories to conduct collaborative value determination using standardized measurement methods. The standard characteristic value is determined by calculating the arithmetic mean after aggregating data from multiple laboratories, eliminating outliers, and simultaneously assessing uncertainty by incorporating homogeneity, stability data, and collaborative measurement bias. This principle reduces systematic and random errors from individual laboratories, ensuring the authoritativeness and metrological traceability of the standard material's characteristic values, and providing a basis for the transfer of measurement values ​​in testing results.

[0119] How to use The rare earth niobium polymetallic ore composition analysis standard material developed in this application is mainly used for laboratory testing quality control, geological prospecting sample analysis quality monitoring, and other scenarios. The specific usage method is as follows: 1. Calibration and Validation of Detection Instruments: Before conducting testing on rare earth niobium polymetallic mineral samples, the laboratory takes an appropriate amount of standard material (sampled according to the smallest packaging size to ensure that the sample quantity meets the requirements of the detection method), performs pretreatment and detection according to the corresponding analytical method of the standard material (such as rare earth elements using alkaline precipitation-cation exchange resin separation-inductively coupled plasma atomic emission spectrometry / mass spectrometry), compares the detection results with the characteristic values ​​of the standard material, calibrates the response signal of the detection instrument (such as ICP-OES, ICP-MS), and verifies whether the instrument's detection accuracy meets the requirements.

[0120] 2. Analytical Method Validation: When a laboratory establishes a new analytical method for rare earth niobium polymetallic minerals, the accuracy and reliability of the method can be validated using the standard reference material. The standard reference material is processed according to the new method, and its characteristic values ​​are measured. If the measurement results are within the uncertainty range of the standard reference material's characteristic values, the new method is feasible and can be used for actual sample testing.

[0121] 3. Quality Control During the Testing Process: When testing rare earth niobium polymetallic mineral samples in batches, a standard substance test is performed every certain number of samples (e.g., every 20 samples). The stability of the testing process is monitored through the test results of the standard substance. If the test results of the standard substance deviate from the characteristic value range, problems in reagents, instruments, and operations must be investigated in a timely manner, and adjustments made before continuing the testing to ensure the accuracy of the batch sample test results.

[0122] 4. Quality monitoring of geological prospecting sample analysis: When conducting prospecting sample analysis for rare earth minerals, geological survey units can incorporate this standard substance as a quality control sample into the analysis process. Referring to the "Requirements for Quality Monitoring and Management of Sample Analysis for Geochemical Survey Projects of China Geological Survey", the reliability of sample analysis data can be evaluated through the test results of the standard substance, ensuring that the ore composition analysis results are true and effective during the prospecting process, and providing support for the evaluation of prospecting results.

[0123] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly efficient method for preparing a rare earth niobium polymetallic ore standard reference, characterized in that, Includes the following steps: (1) Selection of candidates: The rare earth niobium polymetallic mine of Huishishan in Ejin Banner, Inner Mongolia was selected as the candidate standard material; (2) Candidate processing and preparation: The candidate is placed in a clean and ventilated environment to air dry naturally. The dried candidate is crushed by a jaw crusher. The crushed material is placed in a drying equipment to dry. The dried material is then finely crushed by a high-alumina ball mill. Finally, the finely crushed material is mixed. (3) Analytical method confirmation: corresponding determination methods were established for rare earth elements, niobium, tantalum, hafnium, and cesium indium respectively; rare earth elements were determined by alkaline fusion precipitation combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry, niobium, tantalum, and hafnium were determined by closed acid dissolution combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry, and cesium indium were determined by closed acid dissolution combined with inductively coupled plasma atomic emission spectrometry / mass spectrometry or tetraacid decomposition combined with inductively coupled plasma atomic emission spectrometry; (4) Uniformity assessment: The mixed material in step (2) is divided into the smallest packages. Under repeatability test conditions, the material in each smallest package is measured three times in different orders using an inductively coupled plasma atomic emission spectrometer. The average value is taken as the test result. The uniformity of the material is judged by one-way ANOVA. (5) Stability assessment: Long-term stability test and short-term stability test were conducted on the repackaged materials, and the trend analysis of the test results was performed using regression curve method and t test; (6) Determination of characteristic values: Multiple laboratories jointly conduct collaborative determination of material characteristic values ​​using a unified measurement method, and use the arithmetic mean as the standard characteristic value of the material; (7) Determination of characteristic value and uncertainty: Based on the measurement results of step (6), calculate and determine the characteristic value and corresponding uncertainty of the material, and finally obtain the rare earth niobium polymetallic mineral standard material.

2. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (1), before selecting the rare earth niobium polymetallic ore from Huishishan in Ejin Banner, Inner Mongolia as a candidate, the laboratory first screens the candidates based on their compatibility with the rare earth niobium polymetallic ore testing projects it has undertaken, to ensure that the composition of the candidates matches the requirements of the testing projects.

3. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (2), the drying temperature of the drying equipment is controlled at 40-60℃ and the drying time is 8-12h; the fine crushing treatment of the high alumina ball mill makes the particle size of the material reach 200-300 mesh; the mixing treatment is carried out by a three-dimensional mixer with a mixing speed of 20-30r / min and a mixing time of 4-6h.

4. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (3), the method for determining rare earth elements is as follows: the material is mixed with sodium hydroxide at a mass ratio of 1:3-1:5 and then subjected to alkaline melting treatment. The molten product is dissolved in hydrochloric acid, and ammonium chloride solution is added for precipitation. The precipitate is washed and dissolved in nitric acid, and then separated by cation exchange resin. The content of rare earth elements in the eluent after separation is determined by inductively coupled plasma atomic emission spectrometry / mass spectrometry.

5. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (3), the sealing acid dissolution treatment of niobium, tantalum and hafnium adopts a nitric acid-hydrofluoric acid mixed acid system, wherein the volume ratio of nitric acid to hydrofluoric acid is 3:1-5:1, the sealing dissolution temperature is 180-200℃, the dissolution time is 4-6h, and after the dissolution is completed, boric acid solution is added to eliminate fluoride ion interference, and then the niobium, tantalum and hafnium content is determined by inductively coupled plasma atomic emission spectrometry / mass spectrometry.

6. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (4), when evaluating uniformity, at least 15 samples are randomly selected from the smallest package after repackaging, and the sample size of each sample is 0.1-0.2g. In the one-way ANOVA method, if the calculated F value is less than the corresponding critical F value, the material uniformity is deemed to be qualified.

7. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (5), the long-term stability test is conducted over a period of 12 months, with the material's characteristic value measured every 3 months; the short-term stability test is conducted at three temperature conditions: -20℃, 25℃, and 40℃, with a test duration of 48 hours, and the material's characteristic value measured every 12 hours.

8. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (6), the number of laboratories participating in the collaborative determination shall not be less than 5, and all laboratories shall have CMA metrological certification qualifications; the unified determination method shall be the combination of inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry, wherein low-content elements shall be determined by inductively coupled plasma mass spectrometry, and high-content elements shall be determined by inductively coupled plasma atomic emission spectrometry.

9. The efficient preparation method of a rare earth niobium polymetallic ore standard material according to claim 1, characterized in that, In step (2), the crushing chamber lining of the jaw crusher, the inner liner of the drying equipment, and the grinding chamber of the high-alumina ball mill are all treated with polytetrafluoroethylene coating. The grinding balls used in the high-alumina ball mill have an alumina purity of ≥99.5% to avoid introducing impurities during the grinding process.

10. A highly efficient preparation method for a rare earth niobium polymetallic ore standard material according to any one of claims 1-9, characterized in that, The final rare earth niobium polymetallic ore standard material covers 21 elements, including scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, niobium, cesium, hafnium, indium, and tantalum, and the relative standard deviation of the characteristic value of each element is ≤5%.

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