JP2006257477A - METHOD FOR MEASURING QUANTITY OF gamma-Fe2O3 IN IRON ORE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring the quantity of γ-Fe<SB>2</SB>O<SB>3</SB>in iron ore by which the quantity of difficult-to-measure γ-Fe<SB>2</SB>O<SB>3</SB>can be determined with high accuracy. <P>SOLUTION: This measurement method is as follows: (1) the quantity of γ-Fe<SB>2</SB>O<SB>3</SB>in iron ore is obtained on the basis of the area of exothermic peaks observed within the temperature range of 650 to 750°C in the temperature-differential thermal analysis curve measured by the differential scanning calorimetry (DSC) or the differential thermal analysis (DTA) of the iron ore; (2) first, the total quantity of Fe<SB>3</SB>O<SB>4</SB>and γ-Fe<SB>2</SB>O<SB>3</SB>is obtained from the intensity of diffraction peaks observed at a diffraction angle of 29.8 to 30.5° or 42.9 to 43.7° in the X-ray diffraction pattern measured by the X-ray diffraction analysis of iron ore, then the quantity of the Fe<SB>3</SB>O<SB>4</SB>is obtained from acid-soluble iron (II) in the iron ore measured pursuant to JIS M8213, and then the quantity of the γ-Fe<SB>2</SB>O<SB>3</SB>in the iron ore is obtained from the above total quantity of the Fe<SB>3</SB>O<SB>4</SB>and the γ-Fe<SB>2</SB>O<SB>3</SB>and the above quantity of the Fe<SB>3</SB>O<SB>4</SB>; or (3) the total quantity of γ-Fe<SB>2</SB>O<SB>3</SB>is obtained from the intensity of diffraction peaks observed at a diffraction angle of 29.8 to 30.5° or 42.9 to 43.7° in the X-ray diffraction pattern measured by the X-ray diffraction analysis of iron ore after heat treatment is applied to the iron ore in the atmosphere at 400 to 650°. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for evaluating iron ore used for iron making raw materials and the like, and more particularly to a method for measuring the amount of γ-Fe ₂ O ₃ which is one of the mineral compositions constituting iron ore.

Iron ore used for ironmaking raw materials, etc., is a black and magnetic magnetite (hereinafter referred to as magnetite) mainly composed of Fe ₃ O ₄ depending on the chemical form of iron oxide as a main component, that is, the binding state of iron and oxygen. ), Hematite mainly composed of red-colored α-Fe ₂ O ₃ (hereinafter sometimes referred to as hematite), limonite containing about 10% of combined water (hereinafter referred to as limonite). (See Non-Patent Document 1, for example).

  Limonite is hydrous iron oxide, most of which is goethite (hereinafter sometimes referred to as goethite) mainly composed of α-FeOOH, and sputite (hereinafter referred to as lepiite) mainly composed of γ-FeOOH. It is also confirmed that it is a doccrosite).

  Generally, FeO (hereinafter sometimes referred to as wustite) is also known as a chemical form of iron oxide, but it is said to be unstable and difficult to produce naturally, and is hardly present in iron ore. it is conceivable that.

In the actual iron ore, iron oxides and hydroxides composed of various chemical forms of magnetite, hematite and limonite, each of which contains the above-mentioned Fe ₃ O ₄ , α-Fe ₂ O ₃ and FeOOH as a main component, are mixed. The mineral composition of iron ore is complex.

  In the iron making process, massive iron ore and powdered iron ore are agglomerated into sintered ore in advance, and then charged into a blast furnace together with a reducing agent (carbonaceous material such as coke), and heated and reduced in the blast furnace to produce molten iron. Iron is produced, but the reduction characteristics and air permeability in the blast furnace are affected by the mineral composition of iron ore charged into the blast furnace as a raw material.

  In addition, since a predetermined particle size and strength are necessary as raw materials to be charged into the blast furnace, the powdered iron ore is processed into a sintered ore or pellets having a predetermined particle size and strength in advance by an agglomeration process. .

  In this agglomeration of powdered iron ore, for example, in order to produce a desired sintered ore using a sintering process, a plurality of types of powdered iron ore are blended, and a carbonaceous material (fuel) and an auxiliary material are mixed. After mixing and granulating (limestone, silica stone, etc.) to make pseudo-particles, they are charged into a sintering machine, and the carbonaceous material in the raw material charged into the sintering machine is burned with oxygen in the air and powdered. A part of the iron ore is assimilated with the auxiliary material and melted to obtain a sintered ore in which powdered iron ores are sintered together.

  In this sintering process, in order to produce a sintered ore that performs stable sintering operations and satisfies the qualities required as a blast furnace raw material, such as strength, reducibility, and resistance to reduction dusting, Depending on the mineral composition of the iron ore, which is the main raw material, the granulation properties and sinterability to make pseudo particles differ, resulting in the mineral structure and strength of the resulting sinter, the strength, reducibility, reduction dust resistance, etc. It greatly affects.

  For this reason, conventionally, in the iron making process, the mineral composition of iron ore, which is the main raw material, is quantitatively measured and evaluated to control the quality of the iron ore.

  The iron ore evaluation method is defined in detail in, for example, JIS M8202, JIS M8205, JIS M8207, JIS M8208, JIS M8210 and JIS M8230. Among these, JIS M8212 “Iron ore-total iron determination method” and JIS M8213 “Iron ore—acid-soluble iron (II) determination method” are particularly important in the evaluation of iron oxides and iron hydroxides constituting iron ore. , JIS M8211 “Iron Ore-Compound Water Determination Method”.

JIS M8212 - total iron in the iron ore, which is measured according to "ore total iron quantification method" (T.Fe) is, for example, Fe ₃ For _{O 4 72.36mass%, Fe 2 O} 3 in 69. 94 mass% and FeOOH are 62.85 mass%, which are very important indices in considering the quality of iron ore. However, JIS M8212 is applied to a sample having a total iron content of 30 mass% to 72 mass%.

The acid-soluble iron (II) measured according to JIS M8213 “Iron ore-acid-soluble iron (II) determination method” is divalent iron oxide (FeO), but as described above, FeO itself is naturally It is known that FeO detected by this measurement is FeO constituting Fe ₃ O ₄ (reverse spinel lattice structure of FeO and Fe ₂ O ₃ ).

According to the ideal chemical composition of pure Fe ₃ O ₄ , FeO becomes 31.03 mass%, and Fe ₂ O ₃ and FeOOH do not give FeO, so JIS M8213 “Iron ore-acid soluble iron (II) determination method” The amount of Fe ₃ O ₄ in the iron ore can be estimated based on the amount of FeO in the iron ore measured by the above. However, JIS M8213 is applied to a sample having an acid-soluble iron (II) content of 1 mass% to 30 mass%.

  The iron ore compound water (CW) measured according to JIS M8211 “Iron Ore-Compound Water Determination Method” is 950 ° C. after heating the iron ore at 105 ° C. in a nitrogen stream in advance and removing moisture absorption water. It is a measured value of the amount of water released when heated up to.

When considering the three types of iron forms of Fe ₃ O _4, Fe ₂ O ₃ , and FeOOH, the only thing that gives CW is FeOOH (ideally CW = 10.14 mass%). The combined water (CW) of FeOOH can be determined by the “stone-compound water determination method”. However, JIS M8211 is applied to a sample having a compound water content of 0.05 mass% to 10 mass%.

  In addition to iron oxide and iron hydroxide, the actual iron ore contains oxides such as quartz, aluminosilicates such as clay minerals, and carbonates such as limestone and mashed stone. For iron-based compounds of oxides and iron hydroxides, the T.O. It can be generally estimated by Fe, FeO, and CW.

  However, the measurement of iron oxide and iron hydroxide in iron ore and the method for evaluating iron ore defined by the conventional JIS have the following problems.

That is, in the above conventional JIS method for evaluating iron ore, it is possible to estimate the form of three types of iron compounds of Fe ₃ O ₄ , Fe ₂ O ₃ , and FeOOH alone or in combination, but Fe ₂ O ₃ further, it was not possible to quantify by distinguishing the alpha-Fe ₂ O ₃ and γ-Fe ₂ O _3.

In addition, γ-Fe ₂ O ₃ in iron ore has a diffraction pattern almost overlapping with Fe ₃ O ₄ even when an X-ray diffraction method often used for crystal structure analysis of minerals is used, and γ-Fe ₂ It was difficult to distinguish between O ₃ and Fe ₃ O ₄ .

Further, conventionally, γ-Fe ₂ O ₃ present in the mineral, according to structure observation minerals, because they form a continuous solid solution with Fe ₃ O _4, Fe ₃ O iron ore in structure observation _{Both 4} and γ-Fe ₂ O ₃ are indistinguishable and are called martite (see, for example, Non-Patent Document 2). There are attempts to analyze the mineral structure from changes in reflectance (brightness), but quantitative evaluation has not been performed due to strong empirical factors and vague discrimination criteria.

On the other hand, conventionally, Fe ₂ O ₃ contained in iron ore has two types of crystal forms, α-type (α-Fe ₂ O ₃ : hematite) and γ-type (γ-Fe ₂ O ₃ : maghemite). Both were known to differ in chemical properties such as reactivity.

In addition, it has been known that the martite phase in iron ore has fine pores and thus has a high water absorption rate, which adversely affects the granulation properties of the sintered raw material (for example, see Non-Patent Document 3). For this reason, the method of accurately quantifying γ-Fe ₂ O ₃ contained in iron ore is the granulation property of the sintering raw material in the agglomeration process of powdered iron ore, and consequently the productivity of the sintered ore. It was desired to improve the quality of sintered ore.

Ferum Vol. 1 (1996) No. 1 10 p770-776 Mineral Engineering (4th edition) Gihodo Co., Ltd. (issued January 31, 1967) p198-199 Materials and Processes CAMP-ISIJ Vol. 17 (2004) 562-565

In view of the current state of the prior art described above, the present invention is capable of accurately quantifying γ-Fe ₂ O ₃ , which was difficult to measure by conventional methods, among the mineral compositions of iron ore. An object of the present invention is to provide a method for measuring the amount of γ-Fe ₂ O ₃ therein.

As a result of intensive studies to solve the above problems, the present inventors have
(I) γ in iron ore based on the calorific value caused by transformation from γ-Fe ₂ O ₃ to α-Fe ₂ O ₃ observed in a specific temperature range in the temperature-differential heat curve of iron ore -fe ₂ O ₃ amount can be measured,
_{(Ii) γ-Fe 2 O} 3 and iron ore X-ray diffraction pattern of iron ore based on the intensity of the diffraction peaks due to the γ-Fe ₂ O ₃ is observed Fe ₃ O ₄ at a specific diffraction angle in the Fe ₃ with measuring the total amount of O _4, to measure the Fe ₃ O ₄ content of acid-soluble iron iron in the ore that is measured according to JIS M8213 (II), from these, in the iron ore gamma-Fe ₂ Being able to measure the amount of O ₃ , and
(Iii) Intensity of diffraction peaks caused by γ-Fe ₂ O ₃ and Fe ₃ O ₄ observed at a specific diffraction angle in an X-ray diffraction pattern of iron ore after heat treatment at a predetermined temperature in the atmosphere The amount of γ-Fe ₂ O ₃ in iron ore can be measured based on
I found out.

  That is, the gist of the present invention is as follows.

(1) A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, which is 650 to 750 ° C. in a temperature-differential heat curve measured by differential scanning calorimetry or differential thermal analysis of iron ore. based on the area of the exothermic peak observed in the temperature range, γ-Fe ₂ O ₃ of method of measuring iron ore, wherein the determination of the γ-Fe ₂ O ₃ content in the iron ore.

(2) A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, first, a diffraction angle 29.8-30. In an X-ray diffraction pattern measured by X-ray diffraction analysis of iron ore. The total amount of Fe ₃ O ₄ and γ-Fe ₂ O ₃ was determined from the intensity of the diffraction peak observed at 5 ° or 42.9 to 43.7 °, and then measured according to JIS M8213. seeking Fe ₃ O ₄ content of acid-soluble iron in the iron ore (II), wherein Fe ₃ O ₄ and γ-Fe ₂ O in the iron ore from the total amount of ₃ and the Fe ₃ O ₄ weight gamma-Fe ₂ O _{3. A} method for measuring the amount of γ-Fe ₂ O ₃ in iron ore, wherein the amount is determined.

(3) A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, wherein the iron ore is heat-treated in the atmosphere at a temperature of 400 to 650 ° C., and then X-ray diffraction analysis of the iron ore is performed. The total amount of γ-Fe ₂ O ₃ is obtained from the intensity of diffraction peaks observed at diffraction angles of 29.8 to 30.5 ° or 42.9 to 43.7 ° in the X-ray diffraction pattern measured by A method for measuring the amount of γ-Fe ₂ O ₃ in iron ore characterized by

According to the present invention, γ-Fe ₂ O ₃ in iron ore, which has been difficult to measure by conventional methods, can be accurately quantified. γ-Fe ₂ O ₃ is a mineral phase in which Fe ₃ O ₄ and γ-Fe ₂ O ₃ form a continuous solid solution called martite in iron ore and has a high water absorption rate because it has fine pores. It is known to adversely affect the granulation properties of powdered iron ore in the sintering process.

Therefore, γ-Fe ₂ O ₃ in iron ore used as the main raw material of the iron making process by applying the method of the present invention is accurately measured, and the granularity and moisture conditioning of the powdered iron ore in the sintering process, etc. Therefore, it is possible to improve the quality of the sintered ore and the quality of the sintered ore, and the industrial contribution by the present invention is great.

  Details of the present invention will be described below.

First, as a first embodiment of the present invention, γ-Fe ₂ O ₃ observed in a temperature range of 650 to 750 ° C. of iron ore is changed to α-Fe ₂ using a differential scanning calorimetry method or a differential thermal analysis method. gamma-Fe ₂ O ₃ content in the iron ore from the heating amount generated when transformed into O ₃ methods of quantifying described.

  The calorie change accompanying transformation or reaction of a substance can be measured by differential scanning calorimetry (DSC) or differential thermal analysis (DTA).

  DSC is a method of measuring a difference in heat flow flowing into a sample and a reference material as a function of temperature while changing the temperature of the sample and the reference material according to a certain program.

  DTA is a method of measuring the temperature difference between a sample and a reference material as a function of temperature while changing the temperature of the sample and the reference material according to a certain program.

  In both DSC and DTA methods, the sample transition and transformation, and the change in the amount of heat accompanying the reaction can be measured as a function of temperature, or in the case of a constant heating rate, it can be measured as a function of time. Quantitative analysis can also be performed from the area.

FIG. 1 shows (a) Fe ₃ O ₄ , (b) α-Fe ₂ O ₃ , (c) γ-Fe ₂ O ₃ , (d) α-FeOOH, (e) γ-FeOOH, (f) Fe ( The DTA curve of each compound when a pure sample of OH) ₃ is heated from room temperature to 1000 ° C. in the air is shown.

In the air, the Fe ₃ O ₄ pure sample starts to oxidize at a temperature of about 400 ° C. and generates heat when it becomes α-Fe ₂ O ₃ (see FIG. 1A). Furthermore, α-Fe ₂ O ₃ does not change at temperatures up to around 1000 ° C. (see FIG. 1B).

The pure sample of γ-Fe ₂ O ₃ transforms to α-Fe ₂ O ₃ at a temperature around 700 ° C., but this transformation is an exothermic reaction, and thus generates heat near this temperature (FIG. 1 (c), reference).

An α-FeOOH pure sample is dehydrated to a α-Fe ₂ O ₃ at a temperature of 250 to 300 ° C. Since this reaction is an endothermic reaction, an endotherm is produced at this temperature (see FIG. 1 (d)). . The α-Fe ₂ O ₃ produced here has low crystallinity, but the crystallinity improves with increasing temperature.

The pure sample of γ-FeOOH is also dehydrated at a temperature of 250 to 300 ° C. (endothermic reaction) to generate an endotherm, and becomes γ-Fe ₂ O ₃ (see FIG. 1 (e)). Although the crystallinity of the produced γ-Fe ₂ O ₃ is low, when it is further heated, it transforms to α-Fe ₂ O ₃ at a heating temperature around 700 ° C. Since this transformation is an exothermic reaction, an exotherm occurs at this temperature (see FIG. 1 (e)).

The Fe (OH) ₃ pure sample has a lot of adhering water, and when heated, the adhering water dehydrates (endothermic reaction) and generates endotherm, then α-FeOOH dehydrates at a heating temperature of 250-300 ° C. Endotherm, and becomes α-Fe ₂ O ₃ (see FIG. 1 (f)). The α-Fe ₂ O ₃ produced here has low crystallinity, but the crystallinity improves with increasing temperature.

In each mineral phase in iron ore, as shown in FIG. 1 (c), only the pure sample of γ-Fe ₂ O ₃ shows an increase in calorie due to an exothermic reaction at a heating temperature around 700 ° C. FIG. 2 is an enlarged view of the DTA curve of the γ-Fe ₂ O ₃ pure sample of FIG. FIG. 2 shows that the temperature range in which the γ-Fe ₂ O ₃ pure sample is transformed to α-Fe ₂ O ₃ is 650 to 750 ° C.

From the above, from γ-Fe ₂ O ₃ observed in the temperature range of 650 to 750 ° C. in the temperature-differential heat curve measured by differential scanning calorimetry (DSC) or differential thermal analysis (DTA) of iron ore. area of the exothermic peak due to transformation to α-Fe ₂ O _3, that is, the γ-Fe ₂ O ₃ in the ore can be determined on the basis of the calorific value.

Quantification of γ-Fe ₂ O ₃ in iron ore by DTA or DSC is performed by heating the measured DTA curve (temperature-differential heat relationship graph) or DSC curve (temperature-heat amount relationship graph) at 650-750 ° C. This can be done by converting the amount of γ-Fe ₂ O ₃ in the iron ore from the peak area of the exothermic peak observed at the temperature.

As shown in FIG. 1 (e), a pure sample of γ-FeOOH was also dehydrated (endothermic reaction) at 250 to 300 ° C. to produce γ-Fe ₂ O _3, and then at a temperature of 650 to 750 ° C. The heat generation upon transformation to α-Fe ₂ O ₃ is observed.

Therefore, the amount of γ-Fe ₂ O _{3 in} iron ore measured by differential thermal analysis (DTA) or differential scanning calorimetry (DSC) of iron ore is strictly determined from γ-FeOOH by heating. The amount of γ-Fe ₂ O ₃ produced is included.

Although the amount of γ-FeOOH contained in the iron ore used for ordinary iron-making raw materials is small, it is possible to obtain more accurate γ-Fe ₂ O ₃ from X-ray diffractometry or infrared spectroscopy. In order to perform quantitative determination, the amount of γ-FeOOH in the iron ore before heating is determined, and γ− in the iron ore measured by the above-mentioned differential scanning calorimetry (DSC) or differential thermal analysis (DTA). It is preferable to correct the amount of Fe ₂ O ₃ .

  The first embodiment of the present invention is generally performed as follows.

First, the mass of γ-Fe ₂ O ₃ as a pure reagent is measured, DTA or DSC measurement is performed, and the area of the exothermic peak observed in the temperature range of 650 ° C. to 750 ° C. is obtained. To obtain the calorific value per unit mass.

Next, the mass of the iron ore sample is measured, DTA or DSC measurement is performed, the calorific value per unit mass is obtained from the area of the exothermic peak observed in the temperature range of 650 ° C. to 750 ° C. and the sample mass, From the ratio of the calorific value per unit mass of the pure reagent and the calorific value per unit mass of the iron ore sample, the amount of γ-Fe ₂ O ₃ in the iron ore sample is calculated by the following equation (1).

γ-Fe ₂ O ₃ amount (mass%) = (calorific value per unit mass of iron ore / calorific value per unit mass of pure reagent) × 100 (1)

Next, as a second embodiment of the present invention, using an X-ray diffraction analysis method, a diffraction angle of 29.8 to 30.5 ° or 42.9 to 43.7 in an X-ray diffraction pattern of iron ore is used. The total amount of γ-Fe ₂ O ₃ and Fe ₃ O _{4 in} the iron ore is obtained from the diffraction intensity of the peak observed at °, and the iron ore is determined from the amount of ferrous oxide measured using the acid-soluble iron (II) determination method. The amount of Fe ₃ O ₄ in the stone was determined, and from the difference between the total amount of γ-Fe ₂ O ₃ and Fe ₃ O _{4 in} the iron ore and the amount of Fe ₃ O ₄ in the iron ore, γ-Fe ₂ A method for calculating the amount of O ₃ will be described.

First, in the second embodiment of the present invention, a method for obtaining the total amount of γ-Fe ₂ O ₃ and Fe ₃ O ₄ in iron ore using an X-ray diffraction analysis method will be described.

  A powder sample made of iron ore having a particle size of 0.25 mm or less is irradiated with X-rays having a wavelength λ narrowed by a slit, and the crystal structure of the sample components, that is, minerals, from the diffraction angle and diffraction intensity of the diffracted X-rays The composition is identified, and the mineral composition is quantified from the diffraction intensity.

  The X-ray diffraction angle of a powder sample made of iron ore varies depending on the crystal plane depending on the mineral composition, and is determined when a certain condition is satisfied according to the Bragg law shown in the equation (2).

nλ = 2dsinθ (2)
Here, λ is the X-ray wavelength, n is the diffraction order, d is the crystal lattice spacing, and θ is the Bragg angle, that is, the diffraction angle.

FIG. 3 shows pure reagents (a) Fe ₃ O ₄ , (b) α-Fe ₂ O ₃ , (c) γ-Fe ₂ O ₃ , (d) α-FeOOH, (e) γ-FeOOH, ( f) Each X-ray diffraction pattern of Fe (OH) ₃ is shown.

As can be seen from the comparison between (a) and (b) of FIG. 3, the diffraction patterns of Fe ₃ O ₄ and γ-Fe ₂ O ₃ in iron ore are in good agreement. It is difficult to distinguish and quantify Fe ₃ O ₄ and γ-Fe ₂ O ₃ .

On the other hand, the diffraction patterns of Fe ₃ O ₄ and γ-Fe ₂ O _{3 in} the iron ore shown in (a) and (c) of FIG. 3 are shown in (b), (d) to (f) of FIG. Since the diffraction patterns of α-Fe ₂ O ₃ , α-FeOOH, and γ-FeOOH, which are other mineral compositions shown, are completely different from each other, Fe ₃ O ₄ and γ-Fe ₂ O ₃ and others are different depending on the diffraction pattern of iron ore. It can be sufficiently distinguished from the mineral composition.

Note that X-ray diffraction pattern of the Fe (OH) ₃ as shown in (f) of FIG. 3, the intensity is observed peaks at the same diffraction angles as alpha-FeOOH while weak, the Fe (OH) ₃ is It can be seen that α-FeOOH having low crystallinity is contained. However, the diffraction pattern is different from Fe ₃ O ₄ and / or γ-Fe ₂ O ₃ .

From the above, by using the X-ray diffraction analysis, based on the diffraction angle and diffraction intensity of the diffraction peak of Fe ₃ O ₄ in the X-ray diffraction pattern of the iron ore _{γ-Fe 2 O 3, Fe} 3 in the iron ore The total amount of O ₄ and γ-Fe ₂ O ₃ can be calculated.

In the quantitative analysis of each mineral composition using the X-ray diffraction analysis method, the transmission and absorption coefficients differ for each mineral composition, so each mineral composition (Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-Fe ₂ O _3). , Α-FeOOH, γ-FeOOH, Fe (OH) ₃ ) with different compositions, and the diffraction intensity and concentration of diffraction peaks of each mineral composition in the X-ray diffraction pattern of these mixed samples It is preferable to make a calibration curve from the relationship, and to determine the concentration of each mineral composition in the iron ore actually measured using this calibration curve.

Fe ₃ O ₄ and γ-Fe ₂ O ₃ in the iron ore to be measured, and α-Fe ₂ O ₃ , α-FeOOH, γ-FeOOH and Fe (OH) ₃ coexisting with them are all iron. These are oxides and hydroxides, and the X-ray transmission / absorption coefficient of each mineral composition is very close. Therefore, Fe ₃ O ₄ and an object from the relative intensity ratio of characteristic diffraction peaks of the respective mineral composition in the X-ray diffraction pattern of the iron ore, may determine the concentration of γ-Fe ₂ O _3.

Or each mineral composition in the X-ray diffraction pattern of the iron ore diffraction peak of _{(Fe 3 O 4, α-} Fe 2 O 3, γ-Fe 2 O 3, α-FeOOH, γ-FeOOH, Fe (OH) 3) A crystalline substance having a diffraction peak at a diffraction angle that does not overlap with the crystal, for example, calcium fluoride or the like is mixed with a sample iron ore as an internal standard, and the diffraction peak intensity of calcium fluoride and the desired Fe ₃ O ₄ , The concentration may be obtained from the ratio of diffraction peak intensities of γ-Fe ₂ O ₃ .

The X-ray diffraction patterns of Fe ₃ O ₄ and γ-Fe ₂ O ₃ in the iron ore to be measured are diffraction angles of 29.8 to 30.5 °, 35.4 to 35.8 °, 42.9 to Peaks are observed at 43.7 °, 56.8-57.5 °, 62.5-63.2 °, etc., and the diffraction angle for quantifying Fe ₃ O ₄ and γ-Fe ₂ O ₃ is particularly limited. do not have to.

However, depending on the measurement conditions, some diffraction peaks may overlap with diffraction peaks of other mineral compositions. Therefore, it is preferable to overlap diffraction peaks of mineral compositions other than Fe ₃ O ₄ and γ-Fe ₂ O _3. It is preferable to use the peak observed at a diffraction angle of 29.8 to 30.5 ° or 42.9 to 43.7 ° for quantitative analysis.

Next, a method for quantifying Fe ₃ O ₄ in iron ore in the second embodiment of the present invention will be described.

Fe ₃ O ₄ in iron ore is measured by acid-soluble iron (II) in iron ore, that is, in accordance with JIS M8213 “Iron ore-acid-soluble iron (II) determination method”. It is obtained by measuring FeO which is iron oxide and converting from this measured value.

As described above, since FeO in iron ore measured according to JIS M8213 is difficult to produce naturally, FeO measured by this method is Fe ₃ O ₄ (reverse spinel lattice of FeO and Fe ₂ O ₃ It is measured as FeO constituting (structure), and can be converted to Fe ₃ O ₄ in iron ore from the measured value of FeO by the following (2) and (3).

{(Formula amount of FeO: 71.84) / (Formula amount of Fe ₃ O ₄ : 231.53)} × 100
= 31.03 mass% (2)
{(FeO amount determined from JIS M8213: mass%) / 31.03} × 100
= Fe ₃ O ₄ content in iron ore (3)

Table 1 shows pure reagents Fe ₃ O ₄ and α-Fe ₂ O ₃ measured according to JIS M8212 “Iron ore-total iron determination method” and JIS M8213 “Iron ore-acid soluble iron (II) determination method”, T. of γ-Fe ₂ O ₃ , α-FeOOH, γ-FeOOH, Fe (OH) ₃ The result of having measured Fe and FeO is shown. In addition, in () in a table | surface, the theoretical value based on an ideal chemical composition is shown.

From Table 1, the amount of Fe ₃ O ₄ of the pure reagent obtained by conversion from the measured value of FeO measured according to JIS M8213 is in good agreement with the theoretical value based on the ideal chemical composition shown in (). It is clear to do.

  In addition, acid-soluble iron (II) (FeO) measured by JIS M8213 is measured using the fact that divalent iron is easily dissolved in acid. Since trivalent iron and metallic iron constituting the ore are not insoluble in acid, they are slightly detected as FeO. For this reason, the range to which JIS M8213 is applied is a sample having an acid-soluble iron (II) content of 1 mass% to 30 mass%.

Also in Table 1, the apparent FeO value of the reagent γ-Fe ₂ O ₃ is 1.04 mass%, but since Fe ₂ O ₃ does not exist as FeO in the crystal structure, this value is Fe _3. It does not indicate the amount of O ₄ .

From the above, as the second embodiment of the present invention, the X-ray diffraction analysis method is used to set the diffraction angle of 29.8 to 30.5 ° or 42.9 to 43.7 ° in the X-ray diffraction pattern of iron ore. The total amount of γ-Fe ₂ O ₃ and Fe ₃ O _{4 in} the iron ore was determined from the diffraction intensity of the observed peak, and was determined from the amount of ferrous oxide measured according to the acid-soluble iron (II) determination method of JIS M8213. The amount of Fe ₃ O _{4 in the} iron ore was determined, and from the difference between the total amount of γ-Fe ₂ O ₃ and Fe ₃ O _{4 in} the iron ore and the amount of Fe ₃ O ₄ in the iron ore, γ− The amount of Fe ₂ O ₃ can be calculated.

Next, as a third embodiment of the present invention, after iron ore is heat-treated in the atmosphere at a temperature of 400 to 650 ° C., a diffraction angle 29 in an X-ray diffraction pattern measured by X-ray diffraction analysis of the iron ore is 29. A method for obtaining the amount of γ-Fe ₂ O ₃ in the iron ore from the intensity of the diffraction peak observed at .8-30.5 ° or 42.9-43.7 ° will be described.

As described above, the mineral composition (Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , α-FeOOH, γ-FeOOH, Fe (OH) ₃ ) constituting the iron ore is shown in FIG. As shown, when heated from room temperature to 1000 ° C. in the atmosphere, part of the mineral composition at room temperature changes to another due to dehydration, transformation, and the like.

In the X-ray diffraction analysis method, the third embodiment of the present invention uses the structural change depending on the heating temperature of each mineral composition in the iron ore to calculate the iron ore from the X-ray diffraction pattern of the iron ore after the heat treatment. The amount of γ-Fe ₂ O ₃ is quantitatively determined.

4 to FIG. 9 show Fe ₃ O ₄ , α-Fe ₂ O ₃ , and γ when heat treatment is performed at temperatures of 100 ° C., 300 ° C., 500 ° C., 600 ° C., 700 ° C., and 1000 ° C., respectively. _{-Fe 2 O 3, α-FeOOH} , γ-FeOOH, shows a X-ray diffraction pattern of pure samples of Fe (OH) _3.

  Unlike the thermal analysis methods such as DTA and DSC described above, the X-ray diffraction method is difficult to measure while continuously heating an object to be measured. X-ray diffraction patterns of the same pure sample heat-treated at temperatures of 500 ° C., 600 ° C., 700 ° C., and 1000 ° C. were measured.

As described above, the mineral composition constituting the iron ore is heated from the thermal analysis data (DTA curve) of FIG. 1 to dehydrate the adhering water in the pure sample at a temperature of 100 ° C., and α− at the temperature of 300 ° C. The temperature at which FeOOH, γ-FeOOH, Fe (OH) ₃ -bonded water is dehydrated and Fe ₃ O ₄ is oxidized at a temperature of 500 ° C. is the temperature at 600 ° C. and 700 ° C., and γ-Fe ₂ O ₃ is α-Fe _2. The transformation to O ₃ is confirmed.

  The heat treatment temperature of the pure sample, which is the measurement target of the X-ray diffraction pattern, was set based on these findings.

100 ° C. as shown in FIG. 4, 300 ℃, 500 ℃, 600 ℃, 700 ℃, the same was heat-treated at a temperature of 1000 ℃ Fe ₃ O ₄ from the X-ray diffraction pattern of pure samples, Fe ₃ O ₄ diffraction peaks ( Diffraction angle 2θ = 18.28 °, 30.10 °, 35.48 °, 43.08 °, 53.50 °, 56.98 °, 62.56 °, 74.02 °, etc.)) is 500 The diffraction peak of α-Fe ₂ O ₃ (diffraction angle 2θ = 24.12 °, 33.14 °, 35.62 °, 40.86 °, 49.48 °, 54.08 °) almost disappeared at a temperature higher than ℃. Etc.)) becomes larger.

From this result, it can be seen that at temperatures of 500 ° C. and 600 ° C., most of the Fe ₃ O ₄ pure sample was changed to α-Fe ₂ O ₃ . From the DTA curve of the Fe ₃ O ₄ pure sample shown in FIG. 1A as described above, the oxidation of the Fe ₃ O ₄ pure sample and the change to α-Fe ₂ O ₃ at a temperature of 400 ° C. The same can be confirmed from the fact that the process proceeds considerably.

100 ° C. as shown in FIG. 5, 300 ℃, 500 ℃, 600 ℃, 700 ℃, from the X-ray diffraction pattern of the same α-Fe ₂ O ₃ pure sample heated at a temperature of _{1000 ℃, α-Fe 2 O} 3 Diffraction peaks (diffraction angles 2θ = 24.12 °, 33.14 °, 35.62 °, 40.86 °, 49.48 °, 54.08 °, etc.) are heated to 1000 ° C. in the atmosphere. Even if it does not change, the structure of the α-Fe ₂ O ₃ pure sample does not change.

From each X-ray diffraction pattern of the same γ-Fe ₂ O ₃ pure sample heat-treated at temperatures of 100 ° C., 300 ° C., 500 ° C., 600 ° C., 700 ° C. and 1000 ° C. shown in FIG. 6, γ-Fe ₂ O ₃ Diffraction peaks (diffraction angles 2θ = 18.30 °, 30.28 °, 35.70 °, 43.36 °, 53.82 °, 57.36 °, 62.96 °, 74.52 °, etc.) ), The strength hardly changes when heated to 600 ° C. in the atmosphere, and the structure of the γ-Fe ₂ O ₃ pure sample does not change.

However, when a γ-Fe ₂ O ₃ pure sample is further heated to 700 ° C., the diffraction peak of γ-Fe ₂ O ₃ decreases, and instead of this, the diffraction peak of α-Fe ₂ O ₃ (diffraction angle 2θ = 24.12 °, 33.14 °, 35.62 °, 40.86 °, 49.48 °, 54.08 °, etc.) increases in intensity. It can be seen that the Fe ₂ O ₃ pure sample was transformed to α-Fe ₂ O ₃ and the structure was changed.

From each X-ray diffraction pattern of the same α-FeOOH pure sample heat-treated at 100 ° C., 300 ° C., 500 ° C., 600 ° C., 700 ° C. and 1000 ° C. shown in FIG. 2θ = 17.72 °, 21.18 °, 26.30 °, 33.20 °, 36.64 °, 41.16 °, 53.20 °, 58.96 °, 71.52 °, etc.) Is reduced in intensity around 300 ° C., while the diffraction peak of α-Fe ₂ O ₃ (diffraction angle 2θ = 24.12, 33.14, 35.62, 40.86, 49.48, 54. (Peaks such as 08 °) start to increase, and α-FeOOH bonded water dehydrates at this temperature, and the structure changes to α-Fe ₂ O ₃ .

In particular, the increase of the diffraction peak of α-Fe ₂ O ₃ becomes remarkable at a temperature of 500 ° C. or higher, and most of the α-FeOOH pure sample has a crystal structure of α-Fe ₂ O ₃ at a heating temperature of 600 to 700 ° C. It turns out that it changes to.

From each X-ray diffraction pattern of the same γ-FeOOH pure sample heat-treated at 100 ° C., 300 ° C., 500 ° C., 600 ° C., 700 ° C., and 1000 ° C. shown in FIG. 2θ = 14.14 °, 27.04 °, 36.26 °, 38.06 °, 43.34 °, 46.78 °, 52.76 °, 60.16 °, 64.92 °, 68.40 The intensity of the γ-Fe ₂ O ₃ diffraction peaks (diffraction angles 2θ = 30.28 °, 35.70 °, 43.36 °, 53.36 °, 53.degree.) Is also reduced. The peaks of 82 °, 62.96 °, etc.) increase, and at this temperature, the bound water of γ-FeOOH is dehydrated and the structure changes to γ-Fe ₂ O ₃ .

The structure of γ-Fe ₂ O ₃ is maintained up to a temperature of about 600 ° C., but the diffraction peak of α-Fe ₂ O ₃ (diffraction angle 2θ = 24.12 °, 33.14 °, 35.62 °, 40.86 °, 49.48 °, 54.08 °, etc.) increases, and it can be seen that it transforms into α-Fe ₂ O ₃ .

100 ° C. as shown in FIG. 9, 300 ℃, 500 ℃, 600 ℃, 700 ℃, the same Fe (OH) ₃ the X-ray diffraction pattern of pure sample heated at a temperature of 1000 ° C., the Fe (OH) ₃ is Although the crystallinity is low and the amount is small, the diffraction peak of α-FeOOH (diffraction angle 2θ = 17.72 °, 21.18 °, 26.30 °, 33.20 °, 36.64 °, 41.16 °, 53.20 [deg.], 58.96 [deg.], 71.52 [deg.] And the like, and the diffraction peak of Fe (OH) ₃ itself does not appear in the diffraction pattern. This is presumably because Fe (OH) ₃ is amorphous or very fine crystallites.

Diffraction peaks of α-Fe ₂ O ₃ in an X-ray diffraction pattern at a temperature of 300 ° C. or higher (diffraction angles 2θ = 24.12 °, 33.14 °, 35.62 °, 40.86 °, 49.48 ° , 54.08 °, etc.), the α-FeOOH in the Fe (OH) ₃ pure sample dehydrates at a temperature around 300 ° C., and the structure changes to α-Fe ₂ O ₃ , resulting in crystallinity. Decreases.

At this time, Fe (OH) ₃ is also dehydrated, and the element composition becomes Fe ₂ O ₃ . In both cases, the increase in the diffraction peak of α-Fe ₂ O ₃ becomes remarkable when heating at 500 ° C. or higher, and most of them change to the crystal structure of α-Fe ₂ O ₃ at a heating temperature of 600 to 700 ° C. Recognize.

10 (a) to 10 (d) show α-Fe ₂ O ₃ , Fe ₃ O ₄ , γ-Fe ₂ O ₃ pure reagents, α-Fe ₂ O ₃ (80 mass%), Fe ₃ O _4. (15 mass%), and show the γ-Fe ₂ O ₃ X-ray diffraction pattern measured without heating the mixture obtained by mixing the pure reagent (5 mass%). FIGS. 11A to 11D show X-ray diffraction patterns measured by heat-treating the same sample as FIGS. 10A to 10D at a temperature of 600.degree.

The X-ray diffraction peaks (diffraction angles 2θ = 30.12 ° and 43.08 °) of the unheated Fe ₃ O ₄ pure sample shown in FIG. 10 (c) are the unheated γ shown in FIG. 10 (b). It is located near the X-ray diffraction peak of the pure sample of —Fe ₂ O ₃ and is different from the X-ray diffraction peak of the α-Fe ₂ O ₃ pure sample of FIG.

On the other hand, Fe ₃ O ₄ X-ray diffraction peaks of pure samples after the heat treatment at a temperature of 600 ° C. as shown in FIG. 11 (c), Fe ₃ O ₄ at this temperature is transformed into α-Fe ₂ O ₃ structure , the X-ray diffraction peaks, Figure 10 does not heat shown in _{(d) α-Fe 2 O} 3 pure sample, and, after heat treatment at the same temperature as shown in FIG. _{11 (d) α-Fe 2} O _It is consistent with the diffraction peak of ₃ pure samples.

Therefore, in the X-ray diffraction pattern of the unheated mixture shown in FIG. 10A, the diffraction peaks observed at diffraction angles 2θ = 30.12 ° and 43.08 ° are Fe ₃ O ₄ and γ-Fe ₂ O. ₃ overlapped with each other, but in the X-ray diffraction pattern of the mixture after the heat treatment at a temperature of 600 ° C. shown in FIG. 11A, the diffraction angles 2θ = 30.08 ° and 43.16 °. The observed diffraction peak is the diffraction peak of γ-Fe ₂ O ₃ alone.

From the relationship between the heat treatment temperature of the iron ore and the diffraction peak of each mineral composition constituting the iron ore in the X-ray diffraction pattern, in the third embodiment of the present invention, in the X-ray diffraction pattern, γ-Fe ₂ O is used. ₃ and the Fe ₃ O ₄ in the iron ore having a diffraction angle of the diffraction peak at the position overlapping heat treatment, the α-Fe ₂ O ₃ having a diffraction angle of the diffraction peak in a position that does not overlap with gamma-Fe ₂ O ₃ In order to transform, the heat treatment temperature of the iron ore is set to 400 ° C. or higher (see FIG. 4 and FIG. 1 (a)).

Even when the heat treatment temperature of iron ore is low, it is possible to transform Fe ₃ O ₄ in iron ore into α-Fe ₂ O ₃ , but it is necessary to lengthen the holding time until complete transformation. Therefore, it is preferable that the lower limit of the heating temperature when heat-treating iron ore is 600 ° C.

On the other hand, when the heating temperature at the time of heat-treating iron ore exceeds 650 ° C., γ-Fe ₂ O ₃ in the iron ore that is a measurement target in the X-ray diffraction pattern is also transformed into α-Fe ₂ O _3. Therefore, in order to maintain the structure of γ-Fe ₂ O ₃ present in the iron ore at room temperature as it is (see FIGS. 2 and 6), the upper limit of the heating temperature when the iron ore is heat-treated is 650 ° C. Stipulated.

By heating the iron ore at a heating temperature of 400 ° C. or higher, Fe ₃ O ₄ in the iron ore that existed before the heat treatment, and α-FeOOH and Fe (OH) ₃ in the iron ore are either Is transformed to α-Fe ₂ O ₃ (see FIGS. 4, 7 and 9), and the upper limit of the heating temperature is set to 650 ° C. or less, so that γ-Fe ₂ O ₃ in iron ore existing at room temperature and The structure of α-Fe ₂ O ₃ can be maintained as it is (see FIGS. 6 and 5), and the diffraction of γ-Fe ₂ O ₃ in the target iron ore in the X-ray diffraction pattern can be achieved. The peak can be separated from diffraction peaks of other mineral compositions, and the amount of γ-Fe ₂ O ₃ in iron ore can be quantified with high accuracy.

  In addition, when X-ray diffraction is performed on the iron ore heat-treated at 400 ° C. to 650 ° C., the iron ore that has been heated to the room temperature is measured after the heat treatment even if the iron ore in the state where the heating temperature is maintained is measured. May be.

As shown in FIG. 8, when iron ore is heat-treated at a heating temperature of 400 ° C. to 650 ° C., γ-FeOOH in the iron ore existing at room temperature is transformed into γ-Fe ₂ O _3. The amount of γ-Fe ₂ O ₃ quantified from the X-ray diffraction pattern of the iron ore heat-treated at the above heating temperature is also partly the amount of γ-Fe ₂ O ₃ produced by changing the structure of γ-FeOOH included.

Although the amount of γ-FeOOH contained in the iron ore used for ordinary steelmaking raw materials is small, no heat treatment is performed in order to more accurately determine γ-Fe ₂ O ₃ from the X-ray diffraction pattern. It is preferable to quantify γ-FeOOH from the X-ray diffraction pattern of the iron ore and correct the amount of γ-FeOOH determined from the X-ray diffraction pattern of the heat-treated iron ore based on this measured value.

Further, in the quantitative analysis of each mineral composition using the X-ray diffraction analysis method, since the transmission / absorption coefficients differ for each mineral composition, pure reagents (Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ , α-FeOOH, γ-FeOOH, Fe (OH) ₃ ) are mixed, and the diffraction intensity and concentration of the diffraction peak of each mineral composition in the X-ray diffraction pattern of these mixed samples are prepared. It is preferable to make a calibration curve from the above relationship, and use this calibration curve to determine each mineral composition concentration in the iron ore that is actually measured.

The calibration curve is, for example, diffraction peak intensities observed at 29.8 to 30.5 ° and 42.9 to 43.7 ° of Fe ₃ O ₄ and γ-Fe ₂ O ₃ to be measured in the X-ray diffraction pattern. And 23.8 to 24.5, or 32.8 to 33.5 °, or 40.5 to 41.2 °, or 49.1 to 49.8 °, 53 unique to α-Fe ₂ O ₃ , It is created from the relationship between the intensity ratio of the diffraction peak observed at .7 to 54.4 ° and the concentration of each mineral, and then, using this calibration curve, the same X-ray diffraction pattern in the actual iron ore sample is used. It is preferable to obtain the concentration from the intensity ratio of the diffraction peaks.

Alternatively, a crystalline substance having a peak at a diffraction angle that does not overlap with the diffraction peak of each mineral composition, such as calcium fluoride, is mixed with a certain amount of sample iron ore as an internal standard, and the diffraction peak intensity of calcium fluoride and measurement target The concentration may be obtained from the intensity ratio of diffraction peaks of Fe ₃ O ₄ and γ-Fe ₂ O ₃ .

As described above, according to the third embodiment of the present invention, the diffraction angle 29.8 to 30.5 in the X-ray diffraction pattern of iron ore heated at 400 to 650 ° C. using the X-ray diffraction analysis method. Or the amount of γ-Fe ₂ O ₃ in the iron ore from the diffraction intensity of the diffraction peak observed at 42.9 to 43.7 °, and γ-Fe ₂ O ₃ and Fe ₃ in the iron ore are obtained. The amount of Fe ₃ O ₄ can be accurately calculated from the difference between the total amount of O _{4 and} the amount of γ-Fe ₂ O ₃ in the iron ore.

For the four types of iron ores A to D, the following invention example 1: differential thermal analysis (DTA) measurement, invention example 2: X-ray diffraction pattern measurement and JIS M8213 “acid-soluble iron (II)” (FeO) measurement, invention Example 3: The amount of γ-Fe ₂ O _{3 in} iron ore was measured using a high temperature X-ray diffraction pattern (temperature change of X-ray diffraction pattern) measurement.

(Invention Example 1)
Differential thermal analysis (DTA) was performed on iron ores A to D. FIG. 12 shows the DTA measurement result of iron ore A as an example. A portion surrounded by a circle in FIG. 12 is an exothermic peak generated when γ-Fe ₂ O ₃ transformed to α-Fe ₂ O ₃ observed at a heating temperature of 650 ° C. to 750 ° C. FIG. 13 shows the result of extracting the exothermic peak of the DTA curve shown in FIG. 12 and correcting the baseline.

When the baseline is corrected, the peak is clearly observed and the peak area can be easily calculated. When calculated from the peak area (calorific value) per unit mass of iron ore sample and the calorific value per unit mass of pure reagent γ-Fe ₂ O ₃ , the amount of γ-Fe ₂ O _{3 in} iron ore A is 5.6 mass%. Met.

Similarly to the iron ore A, the amount of γ-Fe ₂ O ₃ in the other iron ores B to D was measured. The analysis results of these iron ores A to D are shown in Table 2.

(Invention Example 2)
X-ray diffraction patterns were measured for iron ores A to D that were not heated. FIG. 14 shows the X-ray diffraction patterns of the iron ore samples A, B, C, and D that are not heated.

In the X-ray diffraction patterns of the iron ore samples A, B, C, and D shown in FIG. 14, the diffraction angle 2θ = 29.8 to 30.5 ° indicated by the arrow corresponds to Fe ₃ O ₄ and γ-Fe ₂ O ₃ . From the peak intensity, the total amount of Fe ₃ O ₄ and γ-Fe ₂ O ₃ was determined.

Further, acid-soluble iron (II) (FeO) was measured according to JIS M8213 “Iron ore-acid-soluble iron (II) determination method”, and the amount of Fe ₃ O ₄ was determined from the measured value of FeO. Table 2 shows the total amount of Fe ₃ O ₄ and γ-Fe ₂ O _{3, the} amount of Fe ₃ O ₄ , and the amount of γ-Fe ₂ O ₃ determined from these.

(Invention Example 3)
X-ray diffraction patterns were measured for iron ores A to D heat-treated at 600 ° C. FIG. 15 shows an X-ray diffraction pattern of iron ore heat-treated at 600 ° C.

Since all Fe ₃ O ₄ in the iron ore heat-treated at 600 ° C. is transformed into α-Fe ₂ O ₃ , the diffraction angle 2θ = 29.8-30.5 indicated by the arrow in the X-ray diffraction pattern of FIG. The diffraction peak observed at ° is a diffraction peak derived from γ-Fe ₂ O ₃ . The results of measuring the amount of γ-Fe ₂ O ₃ from this peak intensity are shown in Table 4.

Table 4 shows the total amount of Fe ₃ O ₄ and γ-Fe ₂ O ₃ determined from the X-ray diffraction pattern of the unheated iron ore measured in Invention Example 2, and the amount of γ-Fe ₂ O ₃ The amount of Fe ₃ O ₄ determined from the total amount of Fe ₃ O ₄ and γ-Fe ₂ O ₃ is shown.

Table 5, the invention examples 1~3 γ-Fe ₂ O ₃ amount shown in, Fe ₃ O ₄ content (Inventive Example 2 only) measurements, as a comparative example, Fe ₃ O ₄ weight measured by conventional methods Indicates. In the comparative example, acid-soluble iron (II) (FeO) was measured according to JIS M8213 “Iron ore-acid-soluble iron (II) determination method”, and the amount of Fe ₃ O ₄ in the iron ore was determined from this measured value. It was.

As described above, according to the present invention, Fe ₃ O ₄ and γ-Fe ₂ O ₃ can be separated and quantitatively evaluated, which is impossible with the conventional method, and is suitable as an iron ore quality evaluation method. Can be used for

(A) Fe ₃ O ₄ pure reagent, (b) α-Fe ₂ O ₃ pure reagent, (c) γ-Fe ₂ O ₃ pure reagent, (d) α-FeOOH pure reagent, (e) γ-FeOOH pure reagent It is a figure which shows the differential thermal analysis result of a reagent and (f) Fe (OH) ₃ pure reagent. It is an enlarged view of a differential thermal analysis of the γ-Fe ₂ O ₃ pure reagents. (A) Fe ₃ O ₄ pure reagent, (b) α-Fe ₂ O ₃ pure reagent, (c) γ-Fe ₂ O ₃ pure reagent, (d) α-FeOOH pure reagent, (e) γ-FeOOH pure reagent It is a figure which shows the X-ray-diffraction pattern of a reagent and (f) Fe (OH) ₃ pure reagent. Is a diagram showing an X-ray diffraction pattern of the heat-treated Fe ₃ O ₄ pure reagent (the temperature change in the X-ray diffraction pattern). Is a diagram showing an X-ray diffraction pattern of the heat-treated α-Fe ₂ O ₃ pure reagent (the temperature change in the X-ray diffraction pattern). Is a diagram showing an X-ray diffraction pattern of the heat-treated γ-Fe ₂ O ₃ pure reagent (the temperature change in the X-ray diffraction pattern). It is a figure which shows the X-ray-diffraction pattern (temperature change of a X-ray-diffraction pattern) of the heat-processed (alpha) -FeOOH pure reagent. It is a figure which shows the X-ray-diffraction pattern (temperature change of a X-ray-diffraction pattern) of the heat-processed (gamma) -FeOOH pure reagent. It is a figure which shows the X-ray-diffraction pattern (temperature change of a X-ray-diffraction pattern) of the heat-processed Fe (OH) ₃ pure reagent. (A) a mixture of α-Fe ₂ O ₃ pure reagent (80 mass%), Fe ₃ O ₄ pure reagent (15 mass%) and γ-Fe ₂ O ₃ pure reagent (5 mass%), (b) γ-Fe ₂ O ₃ pure reagent, (c) Fe ₃ O ₄ pure reagent, and a diagram showing the X-ray diffraction pattern of _{(d) α-Fe 2 O} 3 pure reagents. (A) a mixture of α-Fe ₂ O ₃ pure reagent (80 mass%), Fe ₃ O ₄ pure reagent (15 mass%) and γ-Fe ₂ O ₃ pure reagent (5 mass%), (b) γ-Fe ₂ O ₃ pure reagent, (c) Fe ₃ O ₄ pure reagent, and a diagram showing the X-ray diffraction pattern of the sample heated handle _{(d) α-Fe 2 O} 3 pure reagent 600 ° C.. It is a figure which shows the differential thermal analysis result of iron ore A. It is a figure which shows what correct | amended the differential thermal analysis result of the iron ore A. It is a figure which shows the normal temperature X-ray diffraction pattern of (a) Iron Ore A, (b) Iron Ore B, (c) Iron Ore C, and (d) Iron Ore D. It is a figure which shows the X-ray-diffraction pattern of (a) iron ore A, (b) iron ore B, (c) iron ore C, and (d) iron ore D heat-processed at 600 degreeC.

Claims (3)

A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, in a temperature range of 650 to 750 ° C. in a temperature-differential heat curve measured by differential scanning calorimetry or differential thermal analysis of iron ore. based on the area of the observed exothermic peak, the measurement method of the γ-Fe ₂ O ₃ of iron ore, characterized in that to obtain the γ-Fe ₂ O ₃ content in the iron ore. A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, first, a diffraction angle of 29.8 to 30.5 ° in an X-ray diffraction pattern measured by X-ray diffraction analysis of iron ore, Alternatively, the total amount of Fe ₃ O ₄ and γ-Fe ₂ O ₃ is obtained from the intensity of the diffraction peak observed at 42.9 to 43.7 °, and then in the iron ore measured according to JIS M8213. seeking Fe ₃ O ₄ content of acid-soluble iron (II), the γ-Fe ₂ O ₃ of iron ore from the total amount and the Fe ₃ O ₄ content of the Fe ₃ O ₄ and γ-Fe ₂ O ₃ A method for measuring the amount of γ-Fe ₂ O ₃ in iron ore, characterized in that it is obtained. A method for measuring the amount of γ-Fe ₂ O ₃ contained in iron ore, which is measured by X-ray diffraction analysis of iron ore after heat treatment in the atmosphere at a temperature of 400 to 650 ° C. The total amount of γ-Fe ₂ O ₃ is obtained from the intensity of diffraction peaks observed at diffraction angles of 29.8 to 30.5 ° or 42.9 to 43.7 ° in the X-ray diffraction pattern. To measure the amount of γ-Fe ₂ O ₃ in the iron ore.

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