A method for quantitative analysis of main iron-containing minerals in iron ore

Abstract

The present application relates to a kind of iron ore mainly containing iron mineral quantitative analysis method, comprising the following steps: (1) iron ore original XRD, thermogravimetry and chemical composition detection;(2) electron microscope and energy spectrum observation, in situ calibration O element content measurement accuracy;(3) electron microscope and energy spectrum process mineralogy software detection obtains iron phase composition statistical data;(4) based on the set iron ore physical O / Fe element ratio standard identification classification micro area iron phase species, further calibration classification standard and software statistical data are combined with the iron mineral proportion calculated in step (1), complete the accurate identification of micro area iron phase species;(5) quantitative statistical analysis output obtains the complete process mineralogy result of sample iron mineral.This application multi-means combined quantitative analysis method can accurately identify each iron mineral phase, lay the key foundation for process mineralogy data research, design efficient beneficiation process, and improve the utilization rate of iron resources.

Description

Technical Field

[0001] This invention belongs to the technical field of basic analysis and testing methods in the field of mineral processing engineering, and specifically relates to a quantitative analysis method for major iron-bearing minerals in iron ore. Background Technology

[0002] Iron and steel account for over 80% of metal material consumption, and current steel production primarily utilizes a long blast furnace process using iron ore as raw material. The global average iron content of iron ore is 48 wt.%, while the iron ore used in blast furnace production generally requires an iron content of over 60 wt.%. Natural primary iron ore also typically requires beneficiation processes to obtain blast furnace iron ore with the required iron content. Based on the types of iron-bearing minerals, iron ore is mainly classified into magnetite, hematite, limonite, and siderite. Due to the complexity of natural mineral composition, iron ore is often a mixture of two or more iron-bearing minerals. Iron ore beneficiation requires methods such as gravity separation, flotation, magnetic separation, and electrostatic separation, based on the physical and chemical properties of these different minerals, to separate the valuable iron minerals from the gangue minerals. Therefore, accurate quantitative analysis of the composition and properties of minerals such as magnetite, hematite, limonite, and siderite in iron ore is a crucial foundation for process mineralogy data research and the design of efficient beneficiation processes, and is of great significance for improving the utilization rate of iron resources.

[0003] The primary task in studying and analyzing the composition and properties of various iron minerals in iron ore is to accurately distinguish and identify the associated magnetite, hematite, limonite, and siderite minerals. Only then can reliable process mineralogical statistical data be obtained through systematic statistical analysis using computer software and other methods. Currently, the main physical techniques for mineral identification and characterization are optical microscopy and scanning electron microscopy combined with energy dispersive spectroscopy (EDS). Optical microscopy is based on image analysis, distinguishing different iron mineral phases through differences in reflected color. However, relying solely on reflected color information is insufficient to accurately determine the types of iron mineral phases. Furthermore, due to the lack of elemental composition measurements, it is impossible to obtain key chemical composition data for each iron mineral. Scanning electron microscopy combined with EDS, also based on image analysis, distinguishes different iron mineral phases through differences in backscattered grayscale, further supplemented by EDS to detect micro-area elemental composition for further identification. However, since the iron content of natural iron minerals, such as magnetite and hematite, or hematite and limonite, is often similar, their grayscale values ​​under electron microscopy are similar, thus failing to overcome the limitations of image analysis. Furthermore, due to the complex characteristics of natural minerals, the use of non-in-situ standard samples from equipment manufacturers to calibrate energy dispersive spectroscopy instruments results in significant systematic errors in the measurement of elemental content in complex natural minerals, making it difficult to accurately determine the types of iron mineral phases.

[0004] Patents CN 201410797621.7 and CN 201910296908.4 employ a combined quantitative method for determining mineral phases. This method first uses an optical microscope to identify minerals, then guides an MLA electron microscope to collect and name each mineral before batch measurement and analysis. However, this combined method does not fundamentally address the shortcomings of both optical and electron microscopy in measurement and analysis, and it is also difficult to guide and verify the location of extremely finely distributed phases. Patent CN 201510221666.4 uses partial staining of the surface of thin rock sections, placing them under a single-polarization microscope for no more than 15 seconds to observe the staining reaction and determine the rock type of carbonate minerals. This method is only suitable for identifying carbonate minerals and has not yet achieved the goal of guiding in-situ batch analysis and statistical analysis of various iron phases. Patent CN 201610648000.1 uses XRD to determine the phase composition of sintered ore, then uses SEM / EDS analysis to determine the elemental composition within the phases, and finally uses ImageJ software to statistically analyze the area of ​​each mineral phase. However, this method does not directly establish a link between XRD and SEM / EDS. XRD is a qualitative analysis and does not address the quantitative measurement errors and the problem of distinguishing complex phases in the SEM / EDS system. Patent CN201810019963.4 proposes first determining the total amount of the main constituent elements of the mineral in the energy dispersive spectroscopy (EDS) data, then using a threshold limitation method for impurity elements that are prone to misidentification, and automatically identifying and quantitatively analyzing the minerals through logical judgment. This method considers the problem of EDS measurement errors, but it does not address the situation where a single iron mineral has only Fe and O as its main constituent elements, and impurity elements are not used as criteria.

[0005] In summary, there is currently a lack of precise identification, differentiation, and quantitative analysis methods for the main iron-bearing minerals in iron ore. Therefore, there is a need in this field for a multi-method combined quantitative analysis method for the main iron-bearing minerals magnetite, hematite, limonite, and siderite in iron ore, in order to accurately identify each iron mineral phase, lay a key foundation for process mineralogy data research, design of efficient beneficiation processes, and improve the utilization rate of iron resources. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems and provide a quantitative analysis method for the main iron-bearing minerals in iron ore. This method enables a multi-faceted quantitative analysis of the main iron-bearing minerals magnetite, hematite, limonite, and siderite in iron ore, so as to accurately identify each iron mineral phase. This lays a key foundation for process mineralogy data research and the design of efficient mineral processing processes, thereby improving the utilization rate of iron resources.

[0007] To achieve the above objectives, the present invention provides a quantitative analysis method for major iron-bearing minerals in iron ore, comprising the following steps:

[0008] (1) The iron ore samples were subjected to XRD analysis, thermogravimetric analysis under inert atmosphere and chemical composition analysis; among them, XRD analysis was used to obtain the chemical formula of iron-bearing minerals; thermogravimetric analysis was used to obtain the weight loss of the sample at different thermal decomposition temperatures; and chemical composition analysis was used to obtain the total iron content.

[0009] (2) Prepare samples for electron microscopy and energy dispersive spectroscopy observation. Based on the chemical formula of gangue minerals obtained by XRD analysis, measure the O content of quartz, corundum or carbonate minerals in the samples by energy dispersive spectroscopy, and calibrate the accuracy of O content measurement in situ.

[0010] (3) Electron microscopy and energy dispersive spectroscopy software were used to detect the micro-regions of the sample and obtain the statistical results of the composition of the iron-containing micro-regions;

[0011] (4) Based on the established theoretical O / Fe element ratio standard for iron minerals, the types of iron-bearing phases in the micro-area of ​​the energy spectrum are identified and classified. Then, the classification standard is further calibrated by combining the iron mineral ratio calculated in step (1), and the electron microscope and energy spectrum software statistical detection data are checked to complete the accurate identification and determination of the types of iron-bearing phases in the micro-area.

[0012] (5) The software quantitative and image statistical analysis outputs complete process mineralogical results of iron-bearing minerals in iron ore.

[0013] Preferably, the iron ore in step (1) contains at least two of the following: magnetite, hematite, limonite, and siderite.

[0014] As a preferred method, in thermogravimetric analysis, the proportion of iron in limonite and siderite minerals relative to the total iron in the sample is calculated based on the theoretical thermal decomposition reaction weight loss of limonite: Fe2O3·nH2O=Fe2O3+nH2O(g) and the theoretical thermal decomposition reaction weight loss of siderite: 3FeCO3=Fe3O4+CO(g)+2CO2(g).

[0015] Preferably, in the thermogravimetric analysis step (1), the inert protective atmosphere is nitrogen or argon, the thermogravimetric measurement temperature range is between room temperature and ≤900℃, and the heating rate is ≤10℃ / minute.

[0016] Preferably, in step (2), the surface sputtered conductive thin film material used for electron microscopy and energy dispersive spectroscopy observation sample preparation does not contain carbon, and the quartz, corundum or carbonate mineral micro-regions in the selected samples for in-situ calibration of O element content are composed of a single mineral, and the total content of other elements is <2wt.%, with the corresponding mineral chemical formulas being SiO2, Al2O3, CaCO3, and MgCO3.

[0017] Preferably, in step (4), the theoretical O / Fe ratio standard for iron minerals is as follows: the O / Fe atomic ratio of the O element that matches the Fe element is between ≥1.25 and <1.40 for magnetite minerals, between ≥1.40 and <1.60 for hematite minerals, between ≥1.60 and <3.00 for limonite minerals, and between ≥3.00 and <3.50 for siderite minerals.

[0018] As a preferred method, the raw iron ore sample is ground to a size of 74 micrometers or less, and the free water is completely removed by drying at a temperature below 120°C before XRD, thermogravimetric analysis, and chemical composition analysis are performed.

[0019] The software quantitative and image statistical analysis in step (5) of this invention is a conventional technique in this field.

[0020] Specifically, this invention provides a quantitative analysis method for the main iron-bearing minerals magnetite, hematite, limonite, and siderite in iron ore, comprising the following main steps:

[0021] (1) The iron ore sample was ground to a size smaller than 74 micrometers and dried completely at a temperature below 120℃ to remove free water. XRD analysis, thermogravimetric analysis under an inert atmosphere, and chemical composition analysis were then performed. Based on the XRD analysis, the chemical formula of the iron-bearing minerals was obtained; the thermogravimetric analysis was used to obtain the weight loss of the sample at different temperatures; and the chemical composition analysis was used to obtain the total iron (TFe) content. Furthermore, based on the theoretical thermal decomposition reaction weight loss of limonite (Fe2O3·nH2O=Fe2O3+nH2O(g)) and the theoretical thermal decomposition reaction weight loss of siderite (3FeCO3=Fe3O4+CO(g)+2CO2(g), the proportion of iron element in limonite and siderite minerals to the total iron (TFe) of the sample was calculated.

[0022] (2) After the original particle size of the iron ore sample is completely dried and removed by free water at a temperature below 120℃, an electron microscope and energy spectrum observation sample is prepared. Based on the mineral chemical formula obtained by XRD analysis, the O element content of quartz, corundum or carbonate minerals in the sample is measured by energy spectrum, and the O element content measurement accuracy is calibrated in situ.

[0023] (3) Electron microscopy and energy dispersive spectroscopy software were used to detect the micro-regions of the sample and obtain the statistical results of the composition of the iron-containing micro-regions;

[0024] (4) Based on the set iron mineral theory O / Fe element ratio standard, the types of iron-bearing phases in the micro-area of ​​the energy spectrum are identified and classified. Then, the classification standard is further calibrated by combining the siderite and / or limonite ratios calculated in step (1). The upper and lower limits of the O / Fe statistical standard set in the energy spectrum software are corrected and adjusted to the calculated values ​​obtained in step (1) above, so as to complete the accurate identification and determination of the types of iron-bearing phases in the micro-area.

[0025] (5) The software quantitative and image statistical analysis outputs complete process mineralogical results of the main iron-bearing minerals such as magnetite, hematite, limonite and siderite in iron ore.

[0026] Preferably, the iron ore contains at least two of the following four minerals: magnetite, hematite, limonite, and siderite.

[0027] Preferably, the inert protective atmosphere used for thermogravimetric analysis is nitrogen or argon, which does not react with iron minerals, and the thermogravimetric analysis temperature range is from room temperature to ≤900℃, with a heating rate of ≤10℃ / minute.

[0028] Preferably, in step (2), the surface sputtered conductive thin film material used for electron microscopy and energy dispersive spectroscopy observation sample preparation does not contain carbon, and the quartz, corundum or carbonate mineral micro-regions in the selected samples for in-situ calibration of O element content are composed of a single mineral, and the total content of other elements is <2wt.%, with the corresponding mineral chemical formulas being SiO2, Al2O3, CaCO3, and MgCO3.

[0029] Preferably, in step (4), the theoretical O / Fe ratio standard for iron minerals refers to the following: the O / Fe atomic ratio of the O element that matches the Fe element is between ≥1.25 and <1.40 for magnetite minerals, between ≥1.40 and <1.60 for hematite minerals, between ≥1.60 and <3.00 for limonite minerals, and between ≥3.00 and <3.50 for siderite minerals.

[0030] Preferably, in step 4), if the proportion of siderite and / or limonite minerals in the energy dispersive spectroscopy (EDS) statistics is lower than the calculated value obtained in step (1) above, then the lower limit of the set O / Fe statistical standard of the EDS software is lowered, or the upper limit of the set O / Fe statistical standard of the EDS software is raised, up to the calculated value obtained in step (1) above, to complete the accurate identification and determination of the iron-bearing phase type in the micro-area; if the proportion of siderite and / or limonite minerals in the EDS statistics is higher than the calculated value obtained in step (1) above, then the lower limit of the set O / Fe statistical standard of the EDS software is raised, or the upper limit of the set O / Fe statistical standard of the EDS software is lowered, up to the calculated value obtained in step (1) above, to complete the accurate identification and determination of the iron-bearing phase type in the micro-area.

[0031] Compared with existing quantitative analysis methods for magnetite, hematite, limonite, and siderite minerals in iron ore, the advantages of this invention are:

[0032] 1) Combining XRD phase identification, thermogravimetric quantitative calculation of limonite and siderite, and quantitative analysis of chemical composition, the identification and classification criteria of siderite and limonite by electron microscopy energy dispersive spectroscopy are calibrated, avoiding the limitations of a single detection method and the influence of the complex composition of iron minerals on the error of a single detection system.

[0033] 2) In-situ measurement and calibration of single mineral components of quartz, corundum and carbonate by electron microscopy and energy dispersive spectroscopy avoids the error fluctuations that occur when using external samples to calibrate energy dispersive spectroscopy instruments for measuring the elemental content of complex natural minerals, and accurately identifies and distinguishes the micro-regional components of magnetite, hematite, limonite and siderite mineral phases. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the quantitative analysis method for major iron-bearing minerals in iron ore according to the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0036] This invention provides a quantitative analysis method for the main iron-bearing minerals magnetite, hematite, limonite, and siderite in iron ore, comprising the following main steps: (1) XRD qualitative analysis of iron ore samples, and quantitative calculation and analysis of the thermogravimetric and chemical composition of limonite and siderite; (2) In-situ measurement and calibration of the single mineral composition of quartz, corundum, and carbonate by electron microscopy and energy dispersive spectroscopy to ensure the accuracy of O element content measurement; (3) Electron microscopy and energy dispersive spectroscopy to measure and statistically analyze the micro-region composition of iron-bearing phases; (4) Based on the O / Fe ratio of iron minerals and combined with the proportion of limonite and siderite calculated in step (1), the electron microscopy and energy dispersive spectroscopy software statistical detection data are calibrated to complete the accurate identification of the types of iron-bearing phases in the micro-region; (5) The software quantitative and image statistical analysis outputs complete process mineralogical results of the main iron-bearing minerals such as magnetite, hematite, limonite, and siderite in iron ore. This invention avoids the limitations of single detection methods and the detection errors caused by the complex composition of iron minerals. It can accurately identify and distinguish the main iron-bearing minerals such as magnetite, hematite, limonite, and siderite, and obtain reliable process mineralogical results.

[0037] Example 1

[0038] A mixed iron ore of hematite and limonite was prepared by completely drying the raw ore powder with free water at 100℃. The dried ore was then ground to a size of ≤45 micrometers. XRD analysis revealed that the main iron-bearing minerals in the ore were hematite (Fe2O3) and goethite (Limonite) (Fe2O3·H2O). Thermogravimetric analysis (TGA) under a nitrogen atmosphere, with a temperature range of 20℃ to 800℃ and a heating rate of 10℃ / min, showed a limonite weight loss peak at 300℃, with a weight loss of 4.2%. Based on the equation Fe2O3·H2O = Fe2O3 + H2O(g), the iron content in the limonite was calculated to be 26.0% of the total mass. Combined with chemical analysis showing a total iron content of 36.5% (TFe), the iron in the limonite minerals accounted for 71.3% of the total iron in the sample. The thermogravimetric analysis showed no siderite weight loss peak, indicating that the siderite content was extremely low.

[0039] After the original ore powder samples were completely dried and dehydrated with free water at 100℃, samples for electron microscopy and energy dispersive spectroscopy (EDS) were prepared and surface-sprayed with gold. Based on the chemical formula of the gangue minerals obtained from XRD analysis, the minerals contained a quartz phase, SiO2. In-situ measurements of the quartz phase micro-regions in the samples using electron microscopy and EDS showed that, excluding Si and O, the total content of other elements was <1.0 wt.%, considered a single mineral composition. The O / Si atomic ratio, matching the Si element, was 2.4. The O element content measurement coefficient was calibrated to an O / Si atomic ratio of 2.0, referring to the chemical formula of the quartz phase SiO2.

[0040] Using electron microscopy and energy dispersive spectroscopy software, and based on the calibrated O element content measurement coefficient, the micro-regions of the sample were detected. The number of particles was 500,000, and the original statistical results of the composition of the iron-containing phase micro-regions were obtained.

[0041] Based on the established theoretical O / Fe ratio standard for iron minerals, the types of iron-bearing phases in the energy dispersive spectroscopy (EDS) micro-regions were identified and classified. The theoretical O / Fe ratio standard for iron minerals is as follows: magnetite minerals have an O / Fe atomic ratio between ≥1.25 and <1.40; hematite minerals between ≥1.40 and <1.60; limonite minerals between ≥1.60 and <3.00; and siderite minerals between ≥3.00 and <3.50. According to this classification, the software calculated the content distribution rates of magnetite, hematite, limonite, and siderite to be 1.3%, 19.8%, 74.4%, and 0.7%, respectively. The initial calculation of limonite content by the software was higher than the thermogravimetric results; therefore, the lower limit standard for the O / Fe atomic ratio of limonite minerals in the EDS software was adjusted to 1.60 to 1.65. After further calibration of the classification criteria, the software statistically determined the content distribution rates of magnetite, hematite, limonite, and siderite to be 1.3%, 22.9%, 71.3%, and 0.7%, respectively, thus completing the accurate identification and determination of the iron-bearing phases in the micro-area. Other iron elements are distributed in the gangue.

[0042] After the above steps of quantitative and accurate identification of the main iron minerals in iron ore by electron microscopy energy dispersive spectroscopy, the software requantifies and analyzes the images of 500,000 statistical particles to obtain complete process mineralogical results of the main iron-bearing minerals such as magnetite, hematite, limonite, and siderite in iron ore.

[0043] Example 2

[0044] A mixed iron ore of siderite was prepared by completely drying the raw ore powder with free water at 110℃. The dried ore was ground to a thickness of ≤60 micrometers. XRD analysis revealed that the main iron-bearing minerals in the ore were magnetite (Fe3O4), hematite (Fe2O3), and siderite (FeCO3). Thermogravimetric analysis (TGA) was performed under an argon atmosphere with a temperature range of 20℃ to 900℃ and a heating rate of 8℃ / min. The thermogravimetric curve showed a siderite weight loss peak at 500℃, with a weight loss rate of 10.0%. Based on the equation 3FeCO3=Fe3O4+CO(g)+2CO2(g), the iron content in the siderite was calculated to be 14.4% of the total mass. Combined with chemical analysis showing a total iron content of 27.3% TFe, the iron in the siderite minerals accounted for 52.9% of the total iron in the sample. The thermogravimetric curve showed no limonite weight loss peak, indicating that the limonite content was extremely low.

[0045] After the raw ore powder sample with its original particle size was completely dried and desorbed with free water at 110℃, it was used to prepare samples for electron microscopy and energy dispersive spectroscopy (EDS) observation, and the surface was sputtered with gold. Based on the chemical formula of the gangue minerals obtained from XRD analysis, the minerals contained calcite phase CaCO3. In-situ measurement of the calcite phase micro-regions in the sample using electron microscopy and EDS revealed that, excluding Ca, C, and O, the total content of other elements was 1.1 wt.%, considered a single mineral composition. The O / Ca atomic ratio, matching the Ca element, was 2.7. The O element content measurement coefficient was calibrated to an O / Ca atomic ratio of 3.0, referring to the chemical formula of the calcite phase CaCO3.

[0046] Using electron microscopy and energy dispersive spectroscopy software, and based on the calibrated O element content measurement coefficient, the micro-regions of the sample were detected. The number of particles was statistically analyzed to be 550,000, and the original statistical results of the composition of the iron-containing phase micro-regions were obtained.

[0047] Based on the established theoretical O / Fe ratio standard for iron minerals, the types of iron-bearing phases in the energy dispersive spectroscopy (EDS) micro-regions were identified and classified. The theoretical O / Fe ratio standard for iron minerals is as follows: magnetite minerals have an O / Fe atomic ratio between ≥1.25 and <1.40; hematite minerals between ≥1.40 and <1.60; limonite minerals between ≥1.60 and <3.00; and siderite minerals between ≥3.00 and <3.50. According to this classification, the software calculated the content distribution rates of magnetite, hematite, limonite, and siderite to be 24.6%, 19.4%, 5.0%, and 48.7%, respectively. The initial siderite content calculated by the software was lower than the thermogravimetric results; therefore, the lower limit standard for the O / Fe atomic ratio of siderite minerals in the EDS software was adjusted to 3.00 to 2.90. After further calibration of the classification criteria, the software statistically determined that the content distribution rates of magnetite, hematite, limonite, and siderite were 24.6%, 19.4%, 0.8%, and 52.9%, respectively, thus completing the accurate identification and determination of the iron-bearing phases in the micro-area. Other iron elements were distributed in the gangue.

[0048] After the above steps of quantitative and accurate identification of the main iron minerals in iron ore by electron microscopy energy dispersive spectroscopy, the software requantifies and analyzes the images of the 550,000 particles counted, and outputs complete process mineralogical results of the main iron-bearing minerals such as magnetite, hematite, limonite, and siderite in the iron ore.

[0049] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A quantitative analysis method for major iron-bearing minerals in iron ore, comprising the following steps: (1) The iron ore samples were subjected to XRD, thermogravimetric analysis under inert atmosphere and chemical composition analysis; XRD analysis was used to obtain the chemical formula of iron-bearing minerals; thermogravimetric analysis was used to obtain the weight loss of the sample at different temperatures; and chemical composition analysis was used to obtain the total iron content. (2) Prepare electron microscopy and energy dispersive spectroscopy samples. Based on the chemical formula of gangue minerals obtained by XRD analysis, combine energy dispersive spectroscopy to measure the O element content of quartz, corundum or carbonate minerals in the samples, and calibrate the accuracy of O element content measurement in situ. (3) Electron microscopy and energy dispersive spectroscopy (EDS) mineralogy software were used to detect the micro-regions of the sample and obtain statistical results of the composition of the iron-containing micro-regions; (4) Based on the set iron mineral theory O / Fe element ratio standard, the types of iron-bearing phases in the micro-area of ​​the energy spectrum are identified and classified. Then, the classification standard is further calibrated by combining the iron mineral ratio calculated in step (1), and the electron microscope and energy spectrum software statistical detection data are checked to complete the accurate identification and determination of the types of iron-bearing phases in the micro-area. (5) The software quantitative and image statistical analysis outputs complete process mineralogical results of iron-bearing minerals in iron ore; In step (1), the iron ore raw ore contains at least two of the following: magnetite, hematite, limonite, and siderite. In thermogravimetric analysis, based on the theoretical thermal decomposition reaction weight loss of limonite (Fe2O3•nH2O=Fe2O3+nH2O(g)) and the theoretical thermal decomposition reaction weight loss of siderite (3FeCO3=Fe3O4+CO(g)+2CO2(g), the proportion of iron in limonite and siderite minerals relative to the total iron in the samples was calculated.

2. The quantitative analysis method according to claim 1, characterized in that: In step (1) thermogravimetric analysis, the inert protective atmosphere is nitrogen or argon, the thermogravimetric measurement temperature range is between room temperature and ≤900℃, and the heating rate is ≤10℃ / minute.

3. The quantitative analysis method according to claim 1, characterized in that: In step (2), the surface sputtered conductive thin film material used for electron microscopy and energy dispersive spectroscopy observations does not contain carbon. The quartz, corundum, or carbonate mineral micro-regions in the selected samples for in-situ calibration of O element content are composed of a single mineral, and the total content of other elements is <2wt.%. The corresponding mineral chemical formula of quartz is SiO2, the corresponding mineral chemical formula of corundum is Al2O3, and the corresponding mineral chemical formula of carbonate is CaCO3 or MgCO3.

4. The quantitative analysis method according to claim 1, characterized in that: In step (4), the theoretical O / Fe ratio standard for iron minerals is as follows: the O / Fe atomic ratio of the O element that matches the Fe element is between ≥1.25 and <1.40 for magnetite minerals, between ≥1.40 and <1.60 for hematite minerals, between ≥1.60 and <3.00 for limonite minerals, and between ≥3.00 and <3.50 for siderite minerals.

5. The quantitative analysis method according to claim 1, characterized in that: The raw iron ore sample was ground to a size of 74 micrometers or less, and then dried at a temperature below 120°C to completely remove free water before XRD, thermogravimetric analysis, and chemical composition analysis were performed.

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