JP4593369B2 - Method for estimating the chemical form of inorganic minerals in coal. - Google Patents

Description

  The present invention relates to a method for estimating the chemical form of inorganic minerals in coal. More specifically, the chemical form of inorganic minerals in coal used in metallurgical furnaces such as blast furnaces and combustion furnaces such as boilers is measured using a nuclear magnetic resonance (hereinafter sometimes abbreviated as NMR) spectrum measurement method. The present invention relates to a simple estimation method.

  In the operation of a metallurgical furnace such as a blast furnace in an iron making process, an iron-containing raw material such as iron ore and a reducing agent such as coke obtained by carbonizing coal are alternately charged from the top of the furnace. Further, in recent years, a method of replacing a part of coke charged from the top of the blast furnace with a cheaper coal and blowing it with hot air from the tuyere of the blast furnace has been actively performed.

  Also, in the operation of a combustion furnace such as a boiler in a power generation process, coal is reviewed as an alternative fuel for heavy oil that has been used conventionally, and the pulverized coal injection method is particularly attracting attention.

  In this way, a large amount of coal is used in a wide range of fields such as the steel industry and the power generation business, and the quality of the composition and characteristics of the coal used is controlled from the viewpoint of stable operation and improvement of operating rate of each facility. It has become important to do.

  Conventionally, in applications such as the steel industry and power generation business, organic components such as carbon and hydrogen in coal have been managed, but little attention has been paid to inorganic components in coal.

  However, in recent years, for example, it has been involved in the cohesiveness and expansion of inorganic components in coal in coking, and further in the coke reaction pulverization when used in blast furnaces. From the standpoint of promoting the effective use of organic components, the importance of evaluating not only the content of inorganic minerals in coal but also its chemical form is increasing.

  In addition, in the pulverized coal utilization technology in the blast furnace incineration operation of blast furnace and power generation business such as in-house power generation and IPP, inorganic components in the coal are fixed in the pipe in the process of gas conveyance to the injection port, There has also been a problem of lowering.

  The present inventor confirmed that this cause is caused by the coal brand, particle size, moisture, etc. of pulverized coal, as well as inorganic mineral species in the coal. Accurate evaluation of inorganic components in coal is required to improve operation and availability.

As a conventional method for evaluating the chemical form of inorganic components in coal, the amount of Al in the coal and the amount of Si are measured using a chemical analysis method or a fluorescent X-ray analysis (hereinafter abbreviated as XRF) method. Are all derived from kaolin minerals, and the remainder obtained by subtracting the amount of Si calculated from the ideal chemical composition of the kaolin mineral from the amount of Si is used as the Si compound (SiO ₂ etc.) other than the kaolin mineral contained in the coal. Methods for estimating the chemical form of inorganic substances are known.

However, the actual amount of Al in coal does not exist as kaolin minerals, but in addition to kaolin minerals, it exists as compounds such as aluminosilicates (clay minerals) and Al ₂ O _3. May cause a large error in the quantitative results of kaolin minerals.

  Also known is a method for identifying and quantifying inorganic compounds in coal from the position and intensity of diffraction lines using an X-ray diffraction (hereinafter abbreviated as XRD) method.

  However, in this XRD method, diffraction lines are extremely widened for inorganic compounds with low crystallinity such as clay minerals due to the property of measuring diffraction images from the crystal lattice of inorganic compounds, and highly accurate morphological evaluation is possible. It is difficult. In addition, since the XRD method cannot extract information on only specific elements, the diffraction lines of kaolin minerals often overlap with diffraction lines derived from other inorganic minerals, making identification difficult.

  On the other hand, in recent years, a method for estimating an inorganic compound in coal using a nuclear magnetic resonance (NMR) method has been proposed.

Thompson et al. Estimated the type of inorganic mineral in coal from the ratio of tetracoordinated aluminum to the total amount of aluminum obtained from ²⁷ Al-MAS NMR spectrum (see Non-Patent Document 1, for example).

According to this method, ²⁷ Al-MAS NMR spectra of several types of inorganic minerals produced from each production area were measured, and kaolin minerals in which tetracoordinated aluminum did not exist were converted to 0-coordinated aluminum. Those containing 10% are specified as montmorillonite, and those containing 24 to 29% of coordination type aluminum are specified as illite or mica-montmorillonite mixed layer mineral.

Although the method of estimating the inorganic mineral species from the ratio of the four-coordinated aluminum identified from the ²⁷ Al-MAS NMR spectrum can identify the type of inorganic mineral present alone, there are a plurality of types in the coal. It is impossible to estimate the type of each inorganic mineral in coal by this method.

  However, when there are a plurality of types of inorganic minerals, there is a problem that the accuracy of the types of inorganic minerals estimated from only the ratio of the four-coordinated aluminum is considerably lowered.

  In fact, in view of the many years of complex diagenesis, weathering, and hydrothermal alteration, coal has undergone various alterations, and only a single inorganic mineral exists. It is very difficult to think of it, and it is difficult to capture the exact chemical structure of inorganic components in coal by this method.

A ²⁷ Al-NMR spectrum of coal has been measured, and a method for quantifying kaolins in coal based on the ratio of the 6-coordinated Al peak to the integrated value of all Al peaks instead of 4-coordinated Al is proposed (for example, , Patent Document 1). However, this method cannot identify the chemical form of inorganic minerals of a plurality of types of inorganic minerals other than kaolins present in coal.

According to this method, the chemical form of a plurality of inorganic minerals in coal can be identified from the peak position (chemical shift value) in the ²⁷ Al-NMR spectrum of the coal previously identified from each inorganic mineral sample, Unlike the method, it can be applied regardless of the type and number of inorganic minerals.

  However, measurement of these NMR spectra generally requires a long time. If the number of coal types to be measured increases in the future, it may take a long time to evaluate the chemical form. is expected.

  Furthermore, since the setting of measurement conditions for solid NMR spectra is generally complicated and requires specialized measurement and analysis personnel, active evaluation of the chemical form of inorganic minerals by NMR methods at each steelworks site The reality is that it is not easy to do.

Energy & Fuels, 15 (2001) 176 JP 2004-317423 A

  However, the evaluation method has several problems. First, Al and Si are quantified and evaluated by chemical analysis and XRF methods. However, in actual steelmaking sites, even if the coal abundance is almost the same, the inorganic components in the coal heating process are used. There is a difference in the dehydration behavior of the coal and the behavior of the inorganic components in the blast furnace when pulverized coal is blown, and there is a problem that the inorganic components in the coal cannot be managed by component analysis alone.

  In view of the current state of the prior art, the present invention measures the abundance of Al and Si for several types of coal, and shows a correlation with the chemical form of inorganic minerals in the coal specified by the NMR method. It is an object of the present invention to provide a method for simply estimating the chemical form of an inorganic mineral in coal from only the abundance of Al and Si in the coal whose chemical form of the inorganic mineral is unknown.

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

(1) For a plurality of types of coal representing each brand in advance, the chemical form of each inorganic mineral present in the coal is specified by ²⁷ Al-NMR spectroscopy, and the amount of Al and Si in the coal is determined. After preparing an inorganic mineral estimation map measured by a component analysis method and showing the relationship between the amount of Al and Si in the coal and the chemical form of the inorganic mineral, for the coal to be evaluated, the amount of Al in the coal and The amount of Si is measured by component analysis, and the chemical form of the inorganic mineral present in the coal is estimated based on the inorganic mineral estimation map from the amount of Al and the amount of Si in the coal. Of estimating the chemical form of inorganic minerals.

  (2) The method for estimating a chemical form of an inorganic mineral in coal as described in (1) above, wherein the inorganic mineral is a clay mineral and an oxide containing Al as a main component.

(3) measuring the ²⁷ Al-NMR spectrum of the coal, the relation between the peak position of the measured spectrum, premeasured kaolin minerals, smectites, and peak positions in ²⁷ Al-NMR spectrum of mica clay minerals or Al ₂ O ₃ The method for estimating the chemical form of an inorganic mineral in coal according to (1) or (2) above, wherein the chemical form of each inorganic mineral present in the coal is specified based on the above.

  (4) Plot the amount of Al and Si in coal in a two-dimensional graph, classify the chemical forms of inorganic minerals present in the coal corresponding to each plot on the graph, and group them by chemical form The method for estimating a chemical form of an inorganic mineral in coal according to any one of the above (1) to (3), wherein the inorganic mineral estimation map is created by:

(5) The above ²⁷ Al-NMR spectrum measurement method uses a ²⁷ Al-magic angle rotation (MAS) method or a ²⁷ Al-multi-quantum magic angle rotation (MQMAS) method. (4) The estimation method of the chemical form of the inorganic mineral in coal in any one of.

  (6) The chemical form of the inorganic mineral in coal according to any one of (1) to (5) above, wherein a chemical analysis method or a fluorescent X-ray analysis method is used as the component analysis method. Estimation method.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to estimate the chemical form of the inorganic mineral in coal quickly and simply, and its utility value in the industry using coal, such as electric power industry and steel industry, is very high.

  Embodiments of the present invention will be described below.

In the present invention, chemical forms of inorganic minerals in coal, which were impossible by conventional component chemical analysis methods, X-ray fluorescence analysis methods, X-ray diffraction methods, etc., were previously identified by ²⁷ Al-NMR spectrum measurement methods. The estimation of the chemical form of inorganic minerals in coal, which is the object of actual evaluation, is a simple measurement method and uses a component analysis method with a short measurement time, and is based on the measurement results of the amount of Al and Si in coal. The technical philosophy is to quickly and surely carry out.

That is, the present invention specifies the chemical form of each inorganic mineral present in a plurality of coals representing each brand in advance by ²⁷ Al-NMR spectrum measurement, and the amount of Al in these coals. And Si content are measured by component analysis, and after preparing an inorganic mineral estimation map showing the relationship between the amount of Al and Si content in the coal and the chemical form of the inorganic mineral, the coal to be evaluated The amount of Al and the amount of Si are measured by a component analysis method, and the chemical form of the inorganic mineral present in the coal is estimated from the amount of Al and the amount of Si in the coal based on the inorganic mineral estimation map.

  FIG. 1 shows chemical forms of kaolin mineral, smectite, and mica clay mineral as representative examples of inorganic minerals mainly composed of Al and Si in coal.

Generally, in coal, kaolin minerals (Al ₂ Si ₂ O ₅ (OH) ₄ ) and smectites (X (==) as shown in FIG. 1 are used as inorganic minerals mainly composed of Al and Si having different chemical structures. Na, 1 / 2Ca) _0.33 (Al _1.67 Mg _0.33 ) Si ₄ O ₁₀ (OH) ₂ .nH ₂ O), mica clay mineral (K _0.75 (Al _1.75 R (= divalent metal) _0.25. )) (Si _3.50 Al _0.50 ) clay minerals of aluminosilicate such as O ₁₀ (OH) ₂ .nH ₂ O), alumina (Al ₂ O ₃ ), silica (SiO ₂ ) and the like.

The kaolin mineral formed a layer with an octahedral (6-coordinated Al) structure centered on Al ³⁺ ions and a tetrahedral (6-coordinated Si) structure centered on Si ⁴⁺ ions in a 1: 1 ratio. It has a structure.

Smectite is a tetrahedron (tetracoordinated Si) structure centered on Si ⁴⁺ ions that sandwiches an octahedral (6-coordinated Al) structure centered on Al ³⁺ ions from above and below. 1 layer structure is formed and Al ³⁺ ions are substituted for a part of tetracoordinate Si ⁴⁺ ions, so that tetracoordinate Al is also present.

Like the smectite, the mica clay mineral also has a structure in which a SiO ₄ tetrahedral structure and an AlO ₆ octahedral structure are formed in a 2: 1 layer, and a part of the Si ⁴⁺ ions of SiO ₄ is formed. Al ³⁺ ions are replaced. The amount of tetracoordinate Al is characteristically larger than that of smectite.

Al in alumina takes the six-coordinate structure, the silica is in the 4 coordinated Si, taking the structure of Q ⁴ (oxygen in SiO ₄ units are shared with all neighboring SiO ₄ units) ing.

In the present invention, a ²⁷ Al-NMR spectrum measurement method is used as a method for specifying the chemical form of each inorganic mineral present in coal.

²⁷ The chemical form of a compound containing aluminum, such as aluminosilicate or alumina, can be specified by Al-NMR spectrum measurement.

^{Since 27} Al nuclei have a nuclear spin of 2/5 and have nuclear quadrupole interaction, ²⁷ Al-NMR measurement uses the ²⁷ Al-magic angle spinning (hereinafter abbreviated as MAS) method. The ²⁷ Al-Multiple Quantum Magic Angle Spinning (hereinafter abbreviated as MQMAS) method, which can average the nuclear quadrupole interaction, is preferable in order to improve measurement accuracy.

  The MQMAS spectrum is expressed as a two-dimensional spectrum composed of both the F2 axis indicating the linearity of the MAS spectrum and the F1 axis indicating the linearity in which the nuclear quadrupole interaction is averaged, and the apparent chemical shift on the F2 axis. Even for compounds having the same value (hereinafter referred to as MAS shift value), if the quadrupole coupling constant (parameter indicating the magnitude of the nuclear quadrupole interaction) is different, the shift value on the F1 axis (hereinafter referred to as Isotropic shift value) (Notation) are different, so that these compounds can be distinguished on the two-dimensional spectrum.

^In principle, it is also possible to identify the chemical form of inorganic minerals in coal using the ²⁹ Si-NMR spectrum in addition to the ²⁷ Al-NMR spectrum.

However, in ²⁹ Si-NMR spectrum measurement, since the chemical shift anisotropy is generally strong, the line width is likely to be widened, and if there are multiple types of inorganic minerals with similar chemical structures in the coal to be measured. , Separating them may be difficult.

In ²⁹ Si-NMR spectrum measurement, the spin-lattice relaxation time (hereinafter abbreviated as T1) of ²⁹ Si nuclei is generally long, and therefore a long measurement time is required.

For these reasons, in the present invention, it is preferable to use ²⁷ Al-NMR spectrum measurement from the practical aspects such as measurement accuracy and measurement time.

In the present invention, the chemical form of each inorganic mineral present in a plurality of coals representing each brand in advance is specified as follows using the ²⁷ Al-NMR spectrum measurement method.

First, before measuring the ²⁷ Al-NMR spectrum of the coal to be measured, an inorganic mineral mainly composed of Al and Si such as the kaolin mineral, smectite, mica clay mineral, alumina (Al ₂ O ₃ ) A ²⁷ Al-NMR spectrum of each inorganic mineral is measured using a standard sample, and a peak position of each inorganic mineral is specified.

FIG. 2 shows an example of the result of measuring the ²⁷ Al-NMR spectrum of a standard sample of each inorganic mineral (kaolin mineral, smectite, mica clay mineral or alumina) using the ²⁷ Al-multi-quantum magic angle rotation (MQMAS) method. Show.

FIG. 2 summarizes the result of measuring the ²⁷ Al-NMR two-dimensional spectrum for each inorganic mineral standard sample for convenience.

  For example, from the two-dimensional spectrum of FIG. 2, the peaks corresponding to smectite 6-coordinated Al are F2 = 3.4 ppm, F1 = 7.6 ppm, and the peaks corresponding to 6-coordinated Al of mica clay mineral are F2 = 4.2 ppm, F1 = 9.0 ppm, peaks corresponding to kaolin mineral 6-coordinated Al are F2 = 5.7 ppm, F1 = 9.3 ppm, peaks corresponding to 6-coordinated Al of alumina are F2 = 12.5 ppm and F1 = 15.7 ppm, respectively.

  In the two-dimensional spectrum of FIG. 2, there are peaks corresponding to tetracoordinate Al in smectite and mica clay minerals in addition to peaks corresponding to hexacoordinate Al in each inorganic mineral. The peaks of these minerals are difficult to discriminate, so the peaks corresponding to 6-coordinated Al, which are easy to distinguish the peak of each inorganic mineral as the standard inorganic mineral peak, are used for identification and quantification of each inorganic mineral in coal described later. Is preferably used.

In addition, ppm is an abbreviation for “part per million”, and is defined as (peak observation frequency / resonance frequency × 10 ⁶ ) × 10 ⁶ for each peak, and represents the static magnetic field strength of the apparatus used for NMR spectrum measurement. It is a dimensionless unit that does not depend on size.

In the present invention, the peak top position of each inorganic mineral in the ²⁷ Al-NMR spectrum of each inorganic mineral standard sample measured in advance as described above is compared with the peak position in the ²⁷ Al-NMR spectrum of the coal to be measured. By doing so, the chemical form of the inorganic mineral which exists in the said coal can be specified as follows.

FIG. 3 shows an example of the result (two-dimensional spectrum) of the ²⁷ Al-NMR spectrum of the coal of coal H, which is the measurement target shown in Table 1, using the ²⁷ Al-multi-quantum magic angle rotation (MQMAS) method. .

From FIG. 3, the ²⁷ Al-NMR two-dimensional spectrum of coal H, which is the object of measurement, has peak tops at the positions of F1 = 15.7 ppm, F2 = 12.1 ppm, and F1 = 8.5 ppm, F2 = 3.9 ppm. There is a peak showing.

  When these two peak top positions are compared with the peak positions of the standard samples of each inorganic mineral shown in FIG. 2 above, the former corresponds to alumina, and the latter shows the peak top between the smectite and mica clay mineral peaks. Therefore, it can be specified that both a smectite and a mica clay mineral or a mixed layer mineral of both exist.

  In the present invention, a plurality of coals representing each brand are selected in advance, and for these, by performing NMR spectrum measurement as described above, the chemical form of each inorganic mineral present in the coal is specified, In this component analysis, the amount of Al and Si in the coal is measured, and an inorganic mineral estimation map showing the relationship between the group of Al and Si and the chemical form of the inorganic mineral is created.

  In the present invention, the component analysis method for coal does not need to be particularly limited, but in general, chemical analysis using an ICP method or the like and fluorescent X-ray analysis (XRF) method are used. In addition, although the chemical analysis method can accurately quantify Al and Si in coal, it requires complicated procedures such as dissolving a coal sample.

  On the other hand, the XRF method is a method of quantifying from the peak intensity of characteristic X-rays derived from each element, and does not require special pretreatment, and a pelletized solid sample can be directly used for measurement. Furthermore, since multi-element automatic analysis is possible at the same time, quantitative analysis is possible in a shorter time than chemical analysis.

  In consideration of these advantages and disadvantages, it is preferable to select either the chemical analysis method or the XRF method and perform the component analysis method of coal.

  Table 1 shows the mass% of Al and Si measured by a fluorescent X-ray analysis (XRF) method for 15 types of coal (A to O) used for preparing the inorganic mineral evaluation map.

In the present invention, the ²⁷ Al-NMR spectrum measurement is performed on the 15 types of coal (A to O) shown in Table 1, and the chemical form of the inorganic mineral present in the coal is specified as described above. Then, an inorganic mineral evaluation map is created from the relationship between the amounts of Al and Si in the 15 types of coal and the chemical form of the inorganic mineral in the coal.

FIG. 7 shows the 15 types of coal (A to O) shown in Table 1, based on the measurement results of the ²⁷ Al-NMR spectrum and the component analysis, with the amounts of Al and Si in the coal as both axes. By creating a two-dimensional graph, classifying and grouping the chemical forms of inorganic minerals present in the coal corresponding to each plot, the amount of Al and Si in the coal and the inorganic mineral chemistry in the coal It is an example of the inorganic mineral estimation map which showed the relationship with the group according to form.

  The number of coals used for creating the inorganic mineral estimation map and the type of coal brand can be appropriately selected from coals representing the coal brand to be measured, and are not particularly limited.

  According to the study of the present inventors, it has been confirmed that the chemical forms of inorganic components present in coal are roughly classified into five groups depending on the amount of Al and Si present in the coal. Therefore, it is preferable to select at least one kind in each of these groups and a total of five kinds or more, more preferably two or more kinds in each group and a total of ten kinds or more.

  Thereby, the precision for specifying the chemical form of the inorganic mineral in coal from only the amount of Al and Si in coal measured by component analysis based on an inorganic mineral estimation map improves.

  In the present invention, a plurality of coals representing each brand are selected in advance, and for these, by performing NMR spectrum measurement as described above, the chemical form of each inorganic mineral present in the coal is specified, The amount of Al and Si in the coal is measured by component analysis of, and for example, an inorganic mineral estimation map showing the relationship between the amount of Al and Si and the group of inorganic minerals as shown in FIG. 7 is created. .

  And about the coal which should be measured and evaluated that the chemical form of the inorganic substance in the coal is unknown, the amount of Al and the amount of Si in the coal by chemical analysis or component analysis using a fluorescent X-ray analysis (XRF) method, etc. From these measured values, it becomes possible to quickly and reliably estimate the chemical form of the inorganic mineral present in the coal based on the inorganic mineral estimation map.

  According to the present invention, an inorganic mineral estimation map is prepared in advance, and based on the map, the amount of Al and the amount of Si in coal measured only by simple component analysis that does not require specialized techniques such as NMR method. Therefore, it is possible to quickly and reliably estimate the chemical form of the inorganic mineral in the coal to be measured.

  Hereinafter, the present invention will be described by way of examples. However, embodiments of the present invention are not limited to the following conditions without departing from the object and technical idea of the present invention.

Example 1
After 15 types (A to O) of different brands of coal were packed uniformly into a 4 mm diameter NMR solid sample tube, they were set in a 700 MHz solid dedicated NMR device (measured magnetic field strength of 16.4 T), and external It was rotated at a high speed of 18 kHz at a magic angle (54.7 °) with respect to the magnetic field.

The ²⁷ Al resonance frequency at this time was 182.4 MHz. ^{27 As} a chemical shift standard for Al-NMR, 1 mol / l AlCl ₃ aqueous solution was set to -0.1 ppm.

Under the above-mentioned conditions, ²⁷ Al-MQMAS spectra (NMR spectra by ²⁷ Al-multi-quantum magic angle rotation (MQMAS) method) were measured for coals A to O, respectively. As an example, ²⁷ Al-MQMAS spectra of coals A, H, J, and N are shown in FIGS.

Each peak position in ²⁷ Al-MQMAS spectrum of coals A to O measured using the method of the present invention, and kaolin mineral, smectite, mica clay mineral or alumina (Al ₂ O measured beforehand using a standard sample of each inorganic mineral) The chemical form of each inorganic mineral present in coals A to O was identified by comparing the peak top position of each inorganic mineral in the ²⁷ Al-MQMAS spectrum of ₃ ) (see FIG. 2).

  Next, the amount of Al and the amount of Si (% by mass) in the coals A to O were measured by a fluorescent X-ray analysis (XRF) method. The results are shown in Table 1.

Based on the measurement results of the above ²⁷ Al-NMR spectrum of coal A to O and component analysis by XRF method, the horizontal axis represents the amount of Al in the coal (% by mass) and the vertical axis represents the amount of Si (% by mass). By creating a two-dimensional graph, classifying and grouping the chemical forms of inorganic minerals present in the coal corresponding to each plot, the amount of Al and Si in the coal and the inorganic mineral in the coal An inorganic mineral estimation map as shown in FIG. 7 showing the relationship with each chemical form group was prepared.

  From the inorganic mineral estimation map shown in FIG. 7, it became clear that the chemical form of the inorganic mineral in the coal can be roughly classified into five types from the Al amount and the Si amount in the coals A to O.

  In addition, in the classification | category of the chemical form of the inorganic mineral shown in FIG. 7, the inorganic mineral species shown in the parenthesis means that the abundance ratio is small.

  Using the mineral mineral estimation map shown in Fig. 7 and measuring the amount of Al and Si of the new coal species to be measured by component analysis, based on the inorganic mineral estimation map from the measured values, present in the coal It is possible to easily and accurately estimate the chemical form of the inorganic mineral.

  Then, about four types of new coal (P, Q, R, S), the amount of Al in coal and Si amount (mass%) were measured by the component analysis of XRF method, and the inorganic in coal shown in FIG. Using the mineral estimation map, the chemical form of the inorganic mineral present in the new coal (P, Q, R, S) was estimated.

  Table 2 shows the mass% values of Al and Si measured by component chemical analysis of the new coal (P, Q, R, S).

  From the measured values of Al amount and Si amount of coal P, Q, R, and S shown in the inorganic mineral estimation map in coal shown in FIG. It was found that there are inorganic minerals belonging to the chemical forms of kaolin mineral group, smectite + mica clay mineral + alumina group, smectite + (kaolin mineral) group, kaolin mineral + 5-coordinated Al group.

Next, regarding the coals P, Q, R, and S, the chemical forms of the inorganic minerals present in each coal were confirmed using ²⁷ Al-MQMAS spectrum measurement, and the results are shown in FIGS. Thus, the chemical form of the inorganic mineral contained in each coal specified by the MQMAS spectrum measurement is based on the inorganic mineral estimation map in the coal shown in FIG. In agreement with the chemical form of the inorganic mineral estimated from the measured values of the Al content and the Si content of S, the effectiveness of the estimation evaluation according to the present invention was demonstrated.

The average time required for measuring ²⁷ Al-MQMAS spectra of coal P, Q, R, and S was about 25 hours per one type of coal, but Al and Si in the coal were analyzed by XRF component analysis. The quantitative analysis time required only about 1 hour.

  From the comparison of these measurement times, the present invention reliably estimates the chemical form of inorganic minerals in coal in a significantly shorter time than conventional methods for estimating inorganic chemical forms in coal by NMR. Proved to be possible.

It is a schematic diagram which shows the crystal structure of the clay mineral of a layered aluminosilicate. It is a classification diagram of the peak position of the ²⁷ Al-MQMAS spectrum of each inorganic mineral standard sample. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal H. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal A. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal J. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal N. It is a figure which shows the correlation with the abundance of Al and Si in coal, and the chemical form of the inorganic mineral in coal. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal P. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal Q. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal R. It is a figure which shows the ²⁷ Al-MQMAS spectrum of coal S.

Claims (6)

For a plurality of types of coal representing each brand in advance, the chemical form of each inorganic mineral present in the coal is specified by ²⁷ Al-NMR spectrum measurement, and the amount of Al and Si in the coal is determined by component analysis. After preparing an inorganic mineral estimation map showing the relationship between the amount of Al and Si in the coal and the chemical form of the inorganic mineral, for the coal to be evaluated, the amount of Al and Si in the coal An inorganic mineral in coal characterized by measuring by component analysis and estimating a chemical form of the inorganic mineral present in the coal based on the inorganic mineral estimation map from the amount of Al and Si in the coal Of estimating the chemical form.   The said inorganic mineral is the clay mineral and oxide which have Al as a main component, The estimation method of the chemical form of the inorganic mineral in coal of Claim 1 characterized by the above-mentioned. Measured ²⁷ Al-NMR spectrum of coal, based on the relationship between the peak position of the measured spectrum, premeasured kaolin minerals, smectites, and peak positions in ²⁷ Al-NMR spectrum of mica clay minerals or Al ₂ O ₃ The method for estimating the chemical form of an inorganic mineral in coal according to claim 1 or 2, wherein the chemical form of each inorganic mineral present in the coal is specified.   By plotting the amount of Al and Si in the coal in a two-dimensional graph, classifying the chemical forms of inorganic minerals present in the coal corresponding to each plot on the graph, and grouping them by the chemical form, An inorganic mineral estimation map is created, The estimation method of the chemical form of the inorganic mineral in coal of any one of Claims 1-3 characterized by the above-mentioned. The ²⁷ Al-NMR spectrum measurement method uses a ²⁷ Al-magic angle rotation (MAS) method or a ²⁷ Al-multi-quantum magic angle rotation (MQMAS) method. The estimation method of the chemical form of the inorganic mineral in coal of Claim 1.   The method for estimating the chemical form of an inorganic mineral in coal according to any one of claims 1 to 5, wherein a chemical analysis method or a fluorescent X-ray analysis method is used as the component analysis method.

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