A method for measuring the particle size of mineral products

Abstract

This invention discloses a method for measuring the particle size of mineral products, belonging to the field of mineral analysis technology. The method includes: performing automated mineralogical analysis on the sample to obtain the mineral composition and mass percentage content, and calculating the theoretical density; configuring a separation medium according to the theoretical density, performing specific gravity sieving on the sample to obtain the particle projection area characteristics of products at each density level, and calculating the optimal sampling amount for each density level product by combining the optimal sampling amount of a reference material; weighing each density level product separately, measuring the particle size using a laser particle size analyzer to obtain the particle size distribution of each density level product, and finally calculating the overall particle size distribution of the sample based on the yield weighted average of each density level product. This invention effectively eliminates density effect bias and improves the accuracy and representativeness of particle size measurement for complex mineral products.

Description

Technical Field

[0001] This invention relates to the field of mineral analysis technology, and specifically to a method for measuring the particle size of mineral products. Background Technology

[0002] Particle size measurement is a key indicator for evaluating the processing performance of powder materials (such as natural minerals, industrial raw materials, and metallurgical products), directly affecting their effectiveness in subsequent processes such as sorting, smelting, molding, and sintering. Therefore, the rapid and accurate determination of the particle size distribution characteristics of materials is of significant practical importance in fields such as geological exploration, mining production, materials science, and quality control. Currently, the mainstream particle size measurement methods mainly include sieving, sedimentation, and laser diffraction. Among these, laser particle size analyzers are widely used due to their advantages such as fast measurement speed, good repeatability, and wide range. However, the measurement principle of laser particle size analyzers is based on Mie scattering theory, which assumes that the measured particles are spherical, monodisperse, and optically homogeneous. This assumption will produce significant measurement errors when dealing with complex samples with multiple mineral components, uneven density, and irregular shapes that are widely present in nature or industrial production.

[0003] Specifically, existing technologies mainly suffer from the following bottlenecks: First, the "density effect" bias: In laser particle size analysis, the instrument assumes all particles have the same theoretical density to calculate volume distribution, which is then converted into mass distribution. For mineral mixtures with significant density differences (such as the coexistence of galena (ρ~7.6) and quartz (ρ~2.65), this conversion will be severely distorted. The particle size distribution of light minerals (low density) will be overestimated, while the particle size distribution of heavy minerals (high density) will be underestimated, resulting in a final mass-particle size distribution report that deviates significantly from the true situation. Second, the "sampling representativeness" problem: To ensure that the laser particle size analyzer obtains the ideal shading rate (usually 10%~20%), an optimal sample size needs to be determined. Traditional methods often rely on operator experience or simple density estimations for trial and error, lacking scientific basis. For samples with wide particle size distributions or uneven density, inappropriate sampling can easily lead to overloading of fine particles (excessive shading rate) or insufficient number of coarse particles (poor statistical representativeness), both of which will introduce significant errors. Third, the limitations of "image analysis": While automated mineralogical analysis systems based on scanning electron microscopy (such as MLA and QEMSCAN) can accurately analyze the mineral composition, morphology, and equivalent diameter of individual particles, they are essentially two-dimensional cross-sectional analyses. For coarse particles, the cross-sectional size presented on the measurement surface is often smaller than their true particle size, resulting in a systematic "cutting effect." For fine particles, agglomeration during sample preparation is difficult to avoid, leading to distortion in fine-grained measurement results. Therefore, directly using automated mineralogical data for particle size statistics, especially in the two particle size ranges, lacks reliability and accuracy. To overcome the shortcomings of the above-mentioned single technologies, some combined methods have been adopted, but these are usually cumbersome, lack systematicity, and do not solve the key problem of how to scientifically determine the sample quantity of each component after separation using a laser particle size analyzer. Therefore, efficient and accurate integrated measurement has not yet been fundamentally achieved. The invention patent with publication number CN109238928A provides a method for measuring the particle size of mineral processing. It closely integrates mineral particle size characterization with image processing technology. The image processing technology is used to obtain the two-dimensional shape, area and maximum chord length of the mineral particles. Then, the area of ​​the mineral particles is equivalent to the area of ​​an ellipse, and the maximum chord length of the mineral particles is equivalent to the major axis of the ellipse. The minor axis of the ellipse can be calculated using the formula for the area of ​​the ellipse. The minor axis of the ellipse is the particle size of the mineral processing. However, it has the disadvantage that the particle size value is the value measured and processed on the cut surface after sample preparation. On the one hand, the sample preparation is uncontrollable (particle segregation leads to representative error of the measurement surface). On the other hand, the equivalent minor axis of the ellipse cannot reflect the particle size in the actual random direction.

[0004] In view of this, there is an urgent need to develop a new method for measuring mineral particle size that can effectively couple mineral composition information, density differences and optical measurement principles. Through standardized process design, the above-mentioned deviations can be systematically eliminated, thereby obtaining high-precision particle size distribution data that is closer to the true physical state of the material. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method for measuring the particle size of mineral products. This method is based on automated mineralogical preliminary analysis and pre-separation by specific gravity difference using a laser particle size analyzer, and is particularly suitable for natural minerals or industrial powder samples with complex compositions, uneven densities, and a mixture of coarse and fine particles. This measurement method obtains the mineral composition and theoretical density through automated mineralogical analysis, performs pre-sieving using a specific gravity solution, and then calculates the optimal sampling amount for each density level based on the principle of equivalent projected area, ultimately achieving high-precision and repeatable particle size distribution measurement.

[0006] This invention provides a method for measuring the particle size of mineral products, which includes the following steps: S1, Mineral composition and theoretical density calculation: Perform automatic mineralogical analysis on the pretreated sample to obtain the mineral composition and mass percentage content, and calculate the theoretical density of the sample. S2, Density grading: Based on the theoretical density, at least two separation media with different densities are configured, and specific gravity sieving is performed to separate the sample to be tested into multiple density grades. S3, Equivalent Projected Area Sampling: Based on the principle of equivalent projected area, the optimal sampling amount for laser particle size analysis is determined according to the particle projected area characteristics and density characteristics of samples at each density level. S4, Sample particle size measurement and integration: Weigh samples of each density level according to the optimal sampling amount, perform laser particle size measurement respectively, obtain particle size distribution data of each density level, and integrate the overall particle size distribution of the sample by yield weighting.

[0007] As a further improvement of the present invention, in step S1, the formula for calculating the theoretical density is: ρ=Σ(ai×ρi), where ρ is the theoretical density; ai is the mass percentage of the i-th mineral; and ρi is the theoretical density of the i-th mineral.

[0008] As a further improvement of the present invention, in step S2, the density of the separation medium is configured as follows: The density of the high-specific-gravity separation medium is N1 = (1.40~1.50) × ρ; The density of the low-specific-gravity separation medium is N2 = (0.8~0.9) × ρ; The specific process of the specific gravity sieving is as follows: the sample to be tested is placed in the separation medium, and three density grade samples Bn are obtained by sequential sedimentation separation, where n is 1, 2, and 3; specifically divided into: B1 is a high-density component with a density ≥ N1; B2 is a medium-density component with a density between N2 and N1; B3 is a low-density component with a density ≤ N2.

[0009] As a further improvement of the present invention, the separation medium is an organic solution or an inorganic salt solution; The organic solution is one or more combinations of bromoform-ethanol system, iodixanol aqueous solution, chloroform, dichloromethane, and carbon tetrachloride; The inorganic salt solution is one or a combination of sodium iodide aqueous solution, chromium iodide, calcium bromide, zinc bromide, sodium polytungstate solution, and chromium tungborate aqueous solution.

[0010] As a further improvement of the present invention, in step S3, the equivalent projected area sampling includes: S31, Select a reference material with a regular shape, and record the optimal sampling quality m for the reference material to produce the ideal shading rate. 标 True density ρ 标 Equivalent radius R 标 ; S32, perform image analysis on samples Bn of each density level to obtain the equivalent radius R of the average projected area. 样 .n; S33, according to the principle of equivalent area S 标 =S 样 Among them, S 标 S is the area for measuring the particle size of the reference material. 样 For the area to be measured of the sample, then 3 / 4 × m 标 / (ρ 标 ×R 标 ) = 1 / 2 × m 样. n / (ρ 样 .n×R 样 .n), from which the optimal sampling amount m for each density level is calculated. 样. n=1.5×m 标 ×(ρ 样 .n×R 样 .n) / (ρ 标 ×R 标 ).

[0011] As a further improvement of the present invention, the equivalent radius R of the average projected area 样 .n was acquired through automated mineralogical image analysis, pressed R 样 The formula is calculated as n = 0.5 × d50n, where d50n is the median particle size of the density-level sample Bn.

[0012] As a further improvement of the present invention, in step S4, the specific calculation formula for calculating the overall particle size distribution by yield weighted integration is: De=Σ(den×Cn), where De is the overall mass percentage of the sample to be tested in the e-th particle size interval, den is the mass percentage of the n-th density level sample in the e-th particle size interval, and Cn is the yield of the n-th density level sample.

[0013] As a further improvement of the present invention, in step S2, during the specific gravity sieving process, the stirring time for sedimentation separation is 1~5 min, the settling time is 5~10 min, and after separation, the samples of each density grade are dried and weighed to calculate the yield Cn=bn / Σbn, where bn is the mass of the nth density grade sample.

[0014] As a further improvement of the present invention, in step S4, the laser particle size measurement adopts wet or dry dispersion, and the dispersant and ultrasonic conditions are selected according to the sample properties to ensure that the particles are fully deagglomerated; In step S1, the pretreatment involves sequentially performing operations such as rolling, mixing, degassing, precipitation, side cutting, secondary embedding, polishing, and carbon spraying on the sample to be tested to prepare an automated mineralogical analysis sample.

[0015] As a further improvement of the present invention, the sample to be tested is a natural ore, mineral processing product, smelting slag or industrial powder with complex composition and uneven density.

[0016] Beneficial effects: This invention transforms two-dimensional particle size information obtained from automated mineralogical image analysis into a three-dimensional sampling quantity calculation formula for a laser particle size analyzer. It employs a standardized process: automated mineralogical analysis to calculate theoretical density → dynamic configuration of separation medium for pre-separation with specific gravity liquid → calculation of sampling quantity according to density level → laser particle size analyzer graded measurement → yield-weighted merging. By functionally coupling theoretical density parameters, equivalent area algorithms, and yield weights, this invention systematically solves the problems of density effect deviation and sampling representativeness in laser particle size measurement of complex mineral products with multiple mineral components, uneven density, and irregular shapes. It realizes a particle size measurement method that moves from empirical trial and error to theoretical calculation, and from a single instrument to a multi-technology approach, possessing the following technical advantages: 1. High precision, eliminating density effect bias: Through specific gravity pre-separation, mineral components with significant density differences are measured separately, reducing the bias of density differences on particle size measurement, especially improving the measurement accuracy of coarse and fine mixed and density-inhomogeneous samples.

[0017] 2. Good representativeness: Based on automatic mineralogical image analysis, the particle projection area characteristics of products of each density level are obtained. Combined with the equivalent projection area principle of reference material, the optimal sampling amount of samples of each density level is scientifically calculated, which solves the problems of traditional methods relying on experience trial and error, improper sampling leading to poor shading rate or poor statistical representativeness.

[0018] 3. Strong adaptability: It can handle a variety of complex materials with complex components, uneven density, and a mixture of coarse and fine particles, such as natural ores, tailings, smelting slag, and ceramic powders, overcoming the limitations of traditional single measurement methods.

[0019] 4. High degree of standardization of methods: Through standardized and systematic operation procedures, human error is reduced, making the measurement results of different particle size ranges and different density components more stable, and having good inter-laboratory comparability and repeatability.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0022] Figure 1 This is a flowchart illustrating the method for measuring the particle size of mineral products provided in an embodiment of the present invention. Detailed Implementation

[0023] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0025] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0028] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0029] In the description of the embodiments of the present invention, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and are not intended to 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, they should not be construed as limitations on the embodiments of the present invention.

[0030] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0031] To address the technical problem that existing particle size measurement methods struggle to accurately determine the true particle size distribution of complex powder samples with multiple mineral components, uneven density, and irregular shapes, this invention provides a method for measuring the particle size of mineral products. By pre-obtaining the mineral composition and theoretical density of the sample through automated mineralogical analysis, and accordingly configuring a separation medium with a specific gravity to precisely classify the sample according to density, the optimal sampling amount for the laser particle size analyzer is calculated for each density level based on the principle of equivalent projected area and the optimal sampling amount of the reference material. This system couples mineral composition information, density differences, and optical measurement principles, effectively eliminating particle size measurement deviations caused by density effects and improper sampling in traditional methods. This achieves high-precision and highly representative particle size distribution measurement of complex mineral products.

[0032] Please refer to Figure 1 This invention provides a method for measuring the particle size of mineral products, comprising the following steps: S1, Mineral Composition and Density Analysis: Automated mineralogical analysis is performed on the sample to obtain its mineral composition and mass percentage, and the theoretical density ρ of the sample is calculated. The specific process is as follows: Take 3-5g of the sample to be tested and prepare an automated mineral analysis sample, denoted as sample A; The process for preparing samples for automated mineralogical analysis involves a series of pretreatment steps: rolling, mixing, degassing, precipitation, side cutting, secondary embedding, polishing, and carbon spraying. It is important to note that if this pretreatment is omitted and the sample's particle size is directly measured using an automated mineralogical instrument, the particle size error will be significant, especially for excessively coarse or fine samples. Coarse particles will show a shorter exposed length on the measurement surface, and this error is highly random; fine particles will exhibit severe agglomeration, resulting in significant particle size distortion.

[0033] Perform automated mineralogical analysis on sample A (such as MLA, QEMSCAN, TIMA, etc.) to determine the mineral composition of sample A and record its mass percentage content ai (i represents the mineral type); calculate the theoretical density ρ of the sample to be tested, ρ=Σai×ρi.

[0034] Step S2, density fractionation: Based on the theoretical density ρ, at least two separation media (gravity-separated liquids) of different densities are prepared to separate the sample into multiple density fractionation products; the specific process is as follows: Step S21, prepare the specific gravity separation liquid: Prepare two separate liquids with different densities, as follows: For high-density liquids, the density N1 = (1.40~1.50) × ρ; Low specific gravity liquid, density N2 = (0.8~0.9) × ρ; The liquid is preferably a non-toxic and stable organic solution (such as a bromoform-ethanol system, sodium iodide aqueous solution, etc.), and its density can be precisely adjusted.

[0035] Step S22, sieve the sample: Take 10.00~20.00 g of the sample to be tested, and perform specific gravity sieving according to the different specific gravity separation liquids in step S2. Add the sample to the above specific gravity separation liquid, stir and let stand for separation (stir for 1~5 min, stand for 5~10 min), and then use liquids with densities N1 and N2 to perform specific gravity separation in sequence to obtain three density grade samples, denoted as sample Bn (n is 1, 2 and 3, representing greater than or equal to (1.40~1.50)×ρ, less than (1.40~1.50)×ρ but greater than or equal to (0.8~0.9)×ρ, and less than (0.8~0.9)×ρ). Dry and weigh, and record as bn. Specifically divided as: B1: Components with a density ≥ N1; B2: Components with densities between N2 and N1; B3: Components with a density ≤ N2.

[0036] Calculate the yield Cn for each density level, Cn = bn / Σbn.

[0037] S3, Equivalent Projected Area Sampling: Based on the principle of equivalent projected area, the optimal sampling amount for laser particle size analysis is determined according to the particle projected area characteristics and density characteristics of samples at each density level; specifically: S31, record the optimal sampling mass m of the reference material. 标 (This method has been verified to produce sample masses with ideal shading (10%-20% as recommended by the instrument), true density ρ 标 Equivalent radius R 标 Among them, R 标 =0.5×(d20+d40+d60+d80) / 4; where d20, d40, d60, and d80 are the particle sizes corresponding to the cumulative distribution percentiles.

[0038] The reference material is selected from man-made materials with uniform texture and good sphericity, such as standard latex microspheres. Other materials that can be selected are diamond, quartz, or stainless steel spherical particles with regular shape and stable properties.

[0039] S32, for each density grade sample Bn, its particle projected area characteristics are obtained using automated mineralogical image analysis, and its average projected area equivalent radius R is calculated. 样 .n, can take the value R 样 n = 0.5 × d50n (d50n is the median particle size of the product at this density level).

[0040] Then the measured area S of the sample to be tested 样=1 / 2×m 样. n / (ρ 样 .n×R 样 .n).

[0041] S33, Calculate the sample size m of the test sample. 样 .n (n is 1, 2, or 3, representing greater than or equal to (1.40~1.50)×ρ, less than (1.40~1.50)×ρ and greater than or equal to (0.8~0.9)×ρ, less than (0.8~0.9)×ρ), according to the principle of equivalent area, S 标 =S 样 , of which S 标 S is the area for measuring the particle size of the reference material. 样 The area to be measured for the sample is 3 / 4 × m. 标 / (ρ 标 ×R 标 ) = 1 / 2 × m 样. n / (ρ 样 .n×R 样 .n), from which the optimal sampling amount m for each density level is calculated. 样. n=1.5×m 标 ×(ρ 样 .n×R 样 .n) / (ρ 标 ×R 标 ); where ρ 样 .n represents the average density of product Bn for each density grade, taken as 1.5 ρ, 1.15 ρ, and 0.425 ρ, respectively; Among them, the particle size measurement area S of spherical reference material 标 S 标 =3 / 4×m 标 / (ρ 标 ×R 标 ), the measurement area S of the sample to be tested 样 S 样 =1 / 2×m 样. n / (ρ 样 .n×R 样 .n); The derivation process is as follows: Let the standard spherical particle be H. 标 If there are 1, then S 标 The calculation is as follows: m 标 =V 标 ×ρ 标 ; V 标 =H 标 ×4 / 3×π×R 标 3 ; S标 =H 标 ×π×R 标 2 ; Let the sample to be tested be N. 样 If there are n items, then S 样 The calculation is as follows: m 样. n=V 样. n×ρ 样 .n; V 样. n=N 样 .n×(2R 样 .n) 3 ; S 样. n=N 样 .n×(2R 样 .n) 2 .

[0042] Preferably, the reference material should be selected to meet the following requirements: regular shape, good monodispersity, chemical stability, and known density and particle size distribution.

[0043] S4, Particle size measurement and integration: Weigh the products of each density level according to the optimal sampling amount, perform laser particle size measurement respectively, obtain the particle size distribution data of each density level, and integrate them according to the yield to obtain the overall particle size distribution of the sample.

[0044] Calculate the sampling amount m2n according to step S3, weigh the samples of each density level, and use a laser particle size analyzer to measure the particle size to obtain the mass percentage content den of e particle size ranges within each density level (e represents the percentage content of particle size ranges greater than 0.300mm, less than or equal to 0.300mm and greater than 0.100mm, less than or equal to 0.100mm and greater than 0.053mm, less than or equal to 0.053mm and greater than 0.010mm, and less than or equal to 0.010mm, respectively). den represents the percentage content of the e-th particle size range in the n-th specific gravity sample; Then the particle size characteristic of the sample to be tested is De = Σden × Cn.

[0045] Preferably, the particle size measurement can be performed using wet or dry dispersion. Appropriate dispersants and ultrasonic conditions should be selected according to the sample properties to ensure that the particles are fully deagglomerated.

[0046] Example 1 Example 1 of this invention provides a method for measuring the particle size of mineral products. The raw material is a gold concentrate sample from Jiangxi Province with a gold grade of over 100 g / t, a metal sulfide content of approximately 30%, primarily pyrite, followed by arsenopyrite, and containing small amounts of chalcopyrite, galena, and sphalerite; a metal oxide content of approximately 3.00%, mainly hematite and limonite, with small amounts of magnetite and chromite; and a gangue mineral content of approximately 68%, primarily feldspar, mica, and quartz, followed by small amounts of chlorite and amphibole, with other carbonate minerals, kaolinite, apatite, and rutile present in smaller quantities.

[0047] Specifically, the steps include the following: Step S1, Automated mineralogical analysis and theoretical density calculation: Take 5g of the sample to be tested and prepare an automated mineral analysis sample, denoted as sample A; The preparation of the automated mineralogical analysis sample specifically includes the following operations: compaction (compacting and dispersing agglomerated particles in the sample), mixing (mixing the sample with a resin mixture (resin and corresponding curing agent at a volume ratio of 1:0.5~1.0) at a volume ratio of 1:0.5~0.3), degassing (using ultrasonic vibration or vacuum degassing), precipitation (letting stand for 10~20 minutes), side cutting (vertically cutting the sample), secondary mounting (cutting surface facing down, and then curing the sample again with resin), polishing (using a 1-micron abrasive to polish until the sample surface is smooth and without obvious scratches), and carbon spraying (vacuum coating machine to spray carbon at 10~30nm).

[0048] Perform automated mineralogical analysis on sample A (such as the MLA650 automated mineralogical testing and analysis system) to determine the mineral composition and mass percentage content ai (i represents the mineral type), as detailed in Table 1 below; calculate the theoretical density ρ of the sample to be tested.

[0049] ρ=Σ(ai×ρi) =23.27%×5.00+3.54%×6.10+1.52%×7.50+……1.33%×2.85+1.02%×2.61 =1.16+0.22+0.11+……+0.04+0.03 =3.52 g / cm³.

[0050] Table 1. Results of Automated Mineralogical Analysis of Mineral Composition and Content Step S2, density grading: Based on the theoretical density ρ, at least two separation media of different densities are prepared to separate the sample to be tested into multiple density-graded products; specifically: Step S21, prepare the specific gravity separation liquid: Two liquids of different densities are prepared for separation, as shown below: The density of the high-specific-gravity liquid is N1 = 1.45 × ρ = 1.45 × 3.52 = 5.10 g / cm³; The density of a low-density liquid is N2 = 0.85 × ρ = 0.85 × 3.52 = 2.99 g / cm³.

[0051] The liquid is preferably a non-toxic and stable organic solution (sodium iodide aqueous solution).

[0052] Step S22, sieve the sample: Take 10.00 g of the sample to be tested and perform specific gravity sieving according to the different specific gravity liquids in step S2. Use liquids of density N1 and N2 in sequence for specific gravity separation. Specifically, add the sample to the liquid of density N1, stir and let stand for separation (stir for 2 min, let stand for 5 min), and take the upper and lower separated substances. The lower substance is sample B1. Add the upper sample to the liquid of density N2, stir and let stand for separation (stir for 2 min, let stand for 5 min), and take the upper and lower separated substances. The lower substance is sample B2, and the upper separated substance is sample B3. Dry and weigh, record as bn, see Table 2 for details.

[0053] Table 2 Results of specific gravity sieving of the samples Step S3, determine the optimal sampling amount for particle size measurement: S31, record the optimal sampling mass m of the reference material. 标 m 标 =0.47 g (experimentally verified that the shading rate is 14% at this mass).

[0054] The reference material selected was standard silica microspheres, which have uniform texture and good sphericity.

[0055] The true density ρ of a reference substance is measured using a specific gravity bottle. 标 , ρ 标 =1.95 g / cm³; The particle size of the reference material was measured using a laser particle size analyzer under optimal 10% shading conditions. The characteristic values ​​of the particle size distribution, d20, d40, d60, and d80, were measured to be 16.72 μm, 17.93 μm, 20.94 μm, and 23.02 μm, respectively.

[0056] Then the average radius R 标 =0.5×(d20+d40+d60+d80) / 4 =0.5×(16.72+17.93+20.94+23.02μm) / 4 =9.83 μm.

[0057] S32, for each density grade product Bn, its particle projection area characteristics are obtained using automated mineralogical image analysis, and its average projected area equivalent radius R is calculated. 样 .n, can take the value R 样 n = 0.5 × d50n (d50n is the median particle size of the product at this density level).

[0058] S33, Calculate the sample size m of the test sample. 样 .n (n is 1, 2, or 3, representing greater than or equal to (1.40~1.50)×ρ, less than (1.40~1.50)×ρ and greater than or equal to (0.8~0.9)×ρ, less than (0.8~0.9)×ρ), according to the principle of equivalent area, S 标 =S 样 , of which S 标 S is the area for measuring the particle size of the reference material. 样 The area to be measured for the sample is 3 / 4 × m. 标 / (ρ 标 ×R 标 ) = 1 / 2 × m 样. n / (ρ 样 .n×R 样 .n), from which the optimal sampling amount m for each density level is calculated. 样. n=1.5×m 标 ×(ρ 样 .n×R 样 .n) / (ρ 标 ×R 标 ); where ρ 样 .n represents the average density of product Bn for each density grade, taken as 1.5 ρ, 1.15 ρ, and 0.425 ρ respectively; see Table 3 for details.

[0059] Table 3. Results of sampling quantity analysis for specific gravity sieve analysis The calculation is as follows: m 样 .1 = 1.5 × m 标 ×(ρ 样 .1×R 样 .1) / (ρ 标 ×R 标 ) =1.5×0.47×(5.28×7.28) / (1.95×9.83) =1.414 g, where ρ 样 .1=1.5 ρ=1.5×3.52=5.28 g / cm³; m 样.2 = 1.5 × m 标 ×(ρ 样 .2×R 样 .2) / (ρ 标 ×R 标 ) =1.5×0.47×(4.048×13.37) / (1.95×9.83) =1.991 g, where ρ 样 .2=1.15 ρ=1.15×3.52=4.048 g / cm³; m 样 .3 = 1.5 × m 标 ×(ρ 样 .3×R 样 .3) / (ρ 标 ×R 标 ) =1.5×0.47×(1.496×6.31) / (1.95×9.83) =0.347 g, where ρ 样 .3=0.425 ρ=0.425×3.52=1.496 g / cm³.

[0060] Step S4, Measure the particle size characteristics of the sample: The sampling quantity m calculated according to step S3 样. n, weigh samples of each density level respectively, and use a laser particle size analyzer to measure the particle size, and obtain the mass percentage content den of e particle size ranges within each density level (e represents the percentage content of particle size ranges greater than 0.300 mm, less than or equal to 0.300 mm and greater than 0.100 mm, less than or equal to 0.100 mm and greater than 0.053 mm, less than or equal to 0.053 mm and greater than 0.010 mm, and less than or equal to 0.010 mm respectively). den represents the percentage content of the e-th particle size range in the n-th sample; The sample particle size characteristic De = Σden × Cn; see Table 4 for details. For a comparison of the analysis results with conventional methods without pre-separation of specific gravity liquids and without specified sampling amount, see Table 5.

[0061] In this embodiment, the particle size measurement can be performed using wet dispersion, which involves ultrasonic oscillation in ethanol to ensure that the particles are fully deagglomerated.

[0062] Table 4. Results of particle size analysis at each density level D1=Σd1n×Cn =3.26%×7.42%+7.35%×24.55%+2.52%×68.03% =3.76%.

[0063] D2==10.27%×7.42%+20.45%×24.55%+6.96%×68.03% =10.52%.

[0064] D3==21.26%×7.42%+20.53%×24.55%+24.35%×68.03% =23.18%.

[0065] D4==32.37%×7.42%+36.44%×24.55%+37.63%×68.03% =36.95%.

[0066] D5==32.84%×7.42%+15.23%×24.55%+28.54%×68.03% =25.59%.

[0067] Table 5 Comparison Results of Particle Size Analysis As can be seen from the average deviation, the measurement results obtained by not using a fixed sampling amount deviate significantly from those obtained by this method, indicating poor data stability.

[0068] Comparative Example 1 Comparative Example 1 uses the same sample as Example 1, but differs from Example 1 in that: no specific gravity pre-separation is performed, and the steps are as follows: Step S1 is the same; for step S2, no operation is performed and no specific gravity liquid separation is performed. Step S3, determine the optimal sampling amount for particle size measurement: S31, record the optimal sampling mass m of the reference material. 标 m 标 =0.47 g (experimentally verified that the shading rate is 14% at this mass).

[0069] The reference material selected was standard silica microspheres, which have uniform texture and good sphericity.

[0070] The true density ρ of a reference substance is measured using a specific gravity bottle. 标 , ρ 标 =1.95 g / cm³.

[0071] The particle size of the reference material was measured using a laser particle size analyzer under optimal 10% shading conditions. The characteristic values ​​of the particle size distribution, d20, d40, d60, and d80, were measured to be 16.72 μm, 17.93 μm, 20.94 μm, and 23.02 μm, respectively.

[0072] Then the average radius R 标 =0.5×(d20+d40+d60+d80) / 4 =0.5×(16.72+17.93+20.94+23.02μm) / 4 =9.83 μm.

[0073] S32, for sample B, the particle projection area characteristics are obtained using automated mineralogical image analysis, and its average projected area equivalent radius R is calculated. 样 R can be taken 样 =0.5×d50n (d50n is the median particle size of the product at this density level).

[0074] S33, Calculate the sample quantity m of the substance to be tested. 样 According to the principle of equivalent area, S 标 =S 样 , of which S 标 S is the area for measuring the particle size of the reference material. 样 The area to be measured for the sample is 3 / 4 × m. 标 / (ρ 标 ×R 标 ) = 1 / 2 × m 样 / (ρ 样 ×R 样 Therefore, the optimal sampling amount m for each density level sample is calculated. 样 =1.5×m 标 ×(ρ 样 ×R 样 ) / (ρ 标 ×R 标 ); Where ρ 样 The theoretical density is calculated from the results of automated mineralogical analysis: ρ = Σai × ρi; ρ 样 =Σai×ρi =23.27%×5.00+3.54%×6.10+1.52%×7.50+……1.33%×2.85+1.02%×2.61 =1.16+0.22+0.11+……+0.04+0.03 =3.52 g / cm³.

[0075] See Table 6 for details.

[0076] Table 6. Results of Comparative Example 2 m 样 =1.5×m 标 ×(ρ 样×R 样 ) / (ρ 标 ×R 标 ) =1.5×0.47×(3.52×12.33) / (1.95×9.83) =1.60 g.

[0077] Step S4, the following test was conducted: the pre-separation effect without specific gravity was poor. Table 7 Comparison Results of Particle Size Analysis As can be seen from the average deviation, the measurement results obtained without pre-separation sampling based on specific gravity deviate significantly from those obtained by this method, indicating poor data stability.

[0078] In summary, this invention discloses a method for measuring the particle size of mineral products, belonging to the technical field of mineral analysis and particle size analysis of granular materials. The method includes: performing automated mineralogical analysis on the sample to obtain the mineral composition and mass percentage content, and calculating the theoretical density; preparing high-density liquid N1 and low-density liquid N2 according to the theoretical density, and performing specific gravity sieving on the sample to obtain three density grades of products; using automated mineralogical image analysis to obtain the particle projection area characteristics of each density grade of product, and calculating the optimal sampling amount for each density grade of product based on the principle of equivalent projection area, combined with the optimal sampling amount of the reference material; weighing each density grade of product, and measuring the particle size using a laser particle size analyzer to obtain the particle size distribution of each density grade of product; finally, calculating the overall particle size distribution of the sample to be tested based on the yield weighted average of each density grade of product. This invention, through specific gravity pre-separation and scientifically determined sampling amount, effectively eliminates density effect bias and improves the accuracy and representativeness of particle size measurement for complex mineral products.

[0079] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method of measuring the size of a mineral product, characterised by, Comprising the following steps: S1, mineral composition and theoretical density calculation: performing automatic mineralogical analysis on the pretreated sample to be measured to obtain the mineral composition and mass percentage, and calculating the theoretical density of the sample to be measured; S2, density classification: configuring at least two different density separation media based on the theoretical density, performing specific gravity screening, and separating the sample to be measured into multiple density level samples; S3, equivalent projection area sampling: based on the principle of equivalent projection area, determining the optimal sampling amount of laser particle size analysis according to the particle projection area characteristics and density characteristics of each density level sample; S4, sample particle size measurement and integration: weighing each density level sample according to the optimal sampling amount, performing laser particle size measurement, obtaining the particle size distribution data of each density level, and integrating to obtain the overall particle size distribution of the sample according to the yield.

2. A method of measuring the size of particles of a mineral product according to claim 1, characterised in that, In step S1, the calculation formula of the theoretical density is: ρ=Σ(ai×ρi), wherein ρ is the theoretical density; ai is the mass percentage of the i th mineral; ρi is the theoretical density of the i th mineral.

3. A method of measuring the size of particles of a mineral product according to claim 2, characterised in that, In step S2, the density of the separation medium is configured as: High specific gravity separation medium density N1=(1.40~1.50)×ρ; Low specific gravity separation medium density N2=(0.8~0.9)×ρ; The specific process of the specific gravity screening is: placing the sample to be measured in the separation medium, obtaining three density level samples Bn by sequentially settling and separating, n is 1, 2, 3; The specific division is: B1 is the high-density component with density ≥N1; B2 is the medium-density component with density between N2 and N1; B3 is the low-density component with density ≤N2.

4. A method of measuring the size of particles of a mineral product according to claim 3, characterised in that, The separation medium is an organic solution or an inorganic salt solution; The organic solution is one or more combinations of bromoform-ethanol system, iodixanol aqueous solution, chloroform, dichloromethane, carbon tetrachloride; The inorganic salt solution is one or more combinations of sodium iodide aqueous solution, chromium iodide, calcium bromide, zinc bromide, sodium polytungstate solution, and tungsten borate chromium aqueous solution.

5. A method of measuring the size of particles of a mineral product according to claim 3, characterised in that, In step S3, the equivalent projection area sampling includes: S31, selecting a reference substance in a spherical shape, recording the optimum sampling mass m at which the reference substance produces a desired light shielding rate 标 , true density p 标 , equivalent radius R 标 ; S32, image analysis is performed on each density level sample Bn to obtain the average projected area equivalent radius R 样 n; S33, according to the equivalent area principle S 标 = 样 ; wherein S 标 is the reference material particle size measurement area, S 样 is the sample measurement area, then 3 / 4×m 标 / (ρ 标 ×R 标 )=1 / 2×m 样. n / (ρ 样 .n×R 样 .n), thereby calculating the optimal sampling amount m 样. n of each density level sample =1.5×m 标 ×(ρ 样 .n×R 样 .n) / (ρ 标 ×R 标 ).

6. A method of measuring the size of particles of a mineral product according to claim 5, characterised in that, the average projected area equivalent radius R 样 n is obtained by automated mineralogical image analysis, in R 样 n = 0.5 x d50n, wherein d50n is the median particle size of the density class sample Bn.

7. A method of measuring the size of particles of a mineral product according to claim 5, characterised in that, In step S4, the specific calculation formula for calculating the overall particle size distribution by yield weighting integration is: De=Σ(den×Cn), wherein De is the overall mass percentage of the sample to be measured in the e th particle size interval, den is the mass percentage of the n th density level sample in the e th particle size interval, and Cn is the yield of the n th density level sample.

8. A method of measuring the size of particles of a mineral product according to claim 7, characterised in that, In step S2, during the specific gravity screening process, the stirring time of the settling and separating is 1~5min, the standing time is 5~10min, and after separation, the density level samples are dried and weighed to calculate the yield Cn=bn / Σbn, wherein bn is the mass of the n th density level sample.

9. A method of measuring the size of particles of a mineral product according to claim 1, characterised in that, In step S4, the laser particle size measurement adopts wet or dry dispersion, and the dispersant and ultrasonic conditions are selected according to the sample properties to ensure that the particles are fully disaggregated and aggregated; In step S1, the pretreatment is to sequentially perform rolling, mixing, bubble removal, precipitation, side cutting, secondary embedding, grinding and polishing, and carbon spraying on the sample to be measured to prepare an automatic mineralogical analysis sample.

10. A method of measuring the size of particles of a mineral product according to claim 2, characterised in that, The sample to be measured is a natural ore, beneficiation product, smelting slag or industrial powder with complex components and uneven density.

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