Method for selecting a modifier for improving the fluidity of coal, a modifier for improving the fluidity of coal, a method for modifying coal, and a method for producing coke.

Abstract

To provide a selection method for easily selecting a modifier that improves a fluidity of coal from a wide range of compounds, and a modifier for improving a fluidity of coal using the selection method, and a method for using the same.SOLUTION: There is provided a selection method of a modifier for improving a fluidity of coal, wherein a compound in which a solubility parameter value δ (SP value) and a temperature T, whichever is lower of a boiling point or a decomposition start temperature, simultaneously satisfy respective predetermined threshold ranges is selected as a modifier for improving a fluidity of the coal. There are also provided a modifier selected using the selection method, a method for modifying coal using the modifier, and a method for producing coke.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 The present invention relates to a method for selecting a coal fluidity-improving modifier to improve the softening and melting properties (hereinafter also referred to as "fluidity") of coal (including non-coking coal) used in coke production, a modifier selected by the selection method, a method for modifying coal using the modifier, and a method for producing coke. [Background technology] 【0002】 Coke, which is charged into blast furnaces along with iron ore as a smelting raw material, is required to be high in strength. To produce high-strength coke, it is desirable to use coal with high coking properties as the coke raw material. However, coal with low coking properties is not mined exclusively; coal with low coking properties is also mined. Therefore, it is common practice to blend several types (brands) of coal with different properties to create a blended coal, and then use this blended coal as the coke raw material. 【0003】 Coal with high coking properties (also called "high-quality coking coal" or "strong coking coal") is scarce and generally expensive. On the other hand, coal with low coking properties is abundant and relatively inexpensive. Therefore, using coal with low coking properties, so-called "non-coking coal," as a coke raw material is effective in compensating for the shortage of high-quality coking coal and reducing raw material costs. In order to increase the coking properties of non-coking coal so that it can be used as a coke raw material, inexpensive and efficient modifiers and modification processes were needed. 【0004】 Here, the coking property of coal refers to its ability to melt and solidify during carbonization, a property essential for coke production. Since coking property is determined by the characteristics of the coal when it softens and melts (i.e., its fluidity), it is important to use the fluidity values ​​(measured or estimated values) of the coal as an indicator when evaluating the suitability of a particular brand of coal as a raw material for coke. 【0005】 As mentioned above, when producing coke used in blast furnaces and the like, a blend of coal made from several different types of coal is usually used, and various methods have been considered to estimate the strength of coke produced from such a blend. Among these, the "method for estimating coke strength using substrate strength and fluidity as indicators" is generally adopted. This method uses two indicators of coal properties, the mean maximum reflectance of vitrinite (Ro) and the maximum fluidity (MF) measured by a Gieseler plastometer, as parameters to estimate the strength of coke produced from a blend of coal. 【0006】 Specifically, when producing coke by carbonizing coal, two characteristics are combined as factors: the average maximum reflectance (Ro) of vitrinite, which indicates the degree of coalification, and the maximum fluidity (MF), which indicates the coking properties (especially fluidity) of the coal. Based on this combination, the strength of the coke produced is estimated. In other words, in order to ensure the strength of the coke produced, the raw coal is blended so that the average maximum reflectance (Ro) and maximum fluidity (MF) of the blended coal are within a predetermined range. The maximum fluidity (MF), which indicates the fluidity of the coal, is expressed as the number of rotations of the test stirring rod (ddpm) or its common logarithm (logMF = log[ddpm]) due to the characteristics of the test method. Here, "ddpm" is an abbreviation for Dial Division per Minute, and its measurement method is specified in JIS M8801:2008. 【0007】 Blended coal is generally prepared such that the logarithm of the maximum fluidity (logMF) of the blended coal, that is, the weighted average of the logarithms of the maximum fluidity (logMF) of each coking coal mixed, is within the range of 1.0 to 4.0, preferably 2.0 to 3.5 (Non-Patent Literature 1). However, the optimal range of the logarithm of the maximum fluidity (logMF) for the blended coal used may fall outside the above range, as it varies depending on the characteristics of the coke oven used and the coke production conditions. 【0008】 Therefore, in order to produce high-strength coke, the fluidity of coal is a very important factor, and it is necessary to combine several brands to optimize the maximum fluidity (MF) of the blended coal. If the fluidity of the blended coal is insufficient, the strength of the produced coke will decrease (Non-Patent Document 1). 【0009】 As described above, high-quality caking coal for coke production tends to be in short supply, and technologies for modifying non-caking coal to have the same or similar properties as high-quality caking coal, and technologies for producing high-strength coke using non-caking coal are being developed. 【0010】 For example, Patent Document 1 describes that in consideration of the environment, waste plastic is added and processed in a coke oven for the reuse and recycling of waste plastic, and the strength of the coke is improved by this process. 【0011】 Patent Document 2 describes a method for producing coke having the required strength by heating a part or all of the blended coal at a heating rate of 40 to 1000 °C / min so as to be in the temperature range of 250 to 350 °C, and then cooling it at an average cooling rate of 10 °C / min or more from the end temperature of the heat treatment to at least 100 °C (hereinafter referred to as rapid heat treatment), and adding waste plastic to the blended coal. 【0012】 In addition, Patent Document 3 proposes a method for producing high-strength coke by adding and mixing a tar heavy fraction to raw coal and carbonizing the raw coal mixed with this tar heavy fraction. 【0013】 In Patent Document 4, as a method for reforming and utilizing low - cohesive coal, a pretreatment method of raw coal is proposed, in which non - slightly - cohesive coal is pulverized and dried more finely than high - quality cohesive coal, and kneaded with binders such as tar, heavy oil, pitches, etc. to form pseudo - particles. In Patent Document 5, non - cohesive coal is mixed with a non - hydrogen - donating solvent to form a slurry, the slurry is heated to 300 - 420 °C for solvent extraction, after the heated slurry is separated into a liquid part and a non - liquid part, the solvent is separated from the liquid part to obtain extracted coal, non - extracted coal is obtained from the non - liquid part, and the extracted coal with excellent softening fluidity is appropriately blended with the non - extracted coal to be used as a raw material for coke. A method for reforming non - cohesive coal is proposed. In addition, in Patent Documents 6 and 7, low - grade coal containing a large amount of oxygen atoms is heated at a predetermined temperature together with heavy oils, decomposition products of heavy oils are adhered to the surface of the low - grade coal, and a method for efficiently reforming low - grade coal into artificial cohesive coal without generating a large amount of water in the treatment process is described. In Patent Document 8, a method for reforming coal by adding a primary or secondary amine - based compound having an aromatic ring such as phenothiazine or carbazole is described. Furthermore, in Patent Document 9, a technique for mixing a thermosetting composition with coal to obtain formed coke is described. In addition, in Patent Document 10, based on the molecular structure of the material to be selected, the molecular surface area, molecular volume, and polarizability are calculated from calculations using the molecular orbital method, and a method for selecting a compound having a value above a specific threshold as a modifier is described. 【0014】 In the coke manufacturing industry, the boundary between high - quality cohesive coal and non - slightly - cohesive coal is not clearly defined. However, as described above, when manufacturing coke used in blast furnaces, etc., considering that coal is often blended so that the logarithm of the maximum fluidity (logMF) is within the range of 1.0 - 4.0, it can be said that coal corresponding to the range where the logarithm of the maximum fluidity (logMF) is 1.0 or less is low - grade coal that is not suitable as coke used in blast furnaces, etc. by itself. 【Prior Art Documents】 【Patent Documents】 【0015】 [Patent Document 1] Japanese Unexamined Patent Publication No. 48-34901 [Patent Document 2] Japanese Patent Publication No. 2016-210866 [Patent Document 3] Japanese Patent Application Publication No. 11-43675 [Patent Document 4] Japanese Patent Application Publication No. 10-183136 [Patent Document 5] Japanese Patent Publication No. 2006-70182 [Patent Document 6] Japanese Patent Publication No. 2009-13222 [Patent Document 7] Japanese Patent Publication No. 2009-13221 [Patent Document 8] Japanese Patent Publication No. 2014-43545 [Patent Document 9] Japanese Patent Publication No. 2016-56335 [Patent Document 10] Japanese Patent Publication No. 2022-032852 [Non-patent literature] 【0016】 [Non-Patent Document 1] Takashi Miyazu et al., Japan Steel Pipe Technical Report, 67 (1975), p.125. [Non-Patent Document 2] Seiji Nomura et al., Journal of the Japan Energy Society, 81 (2002), p. 728. [Non-Patent Document 3] Yuzo Sanada, Journal of the Fuel Association, 57 (1978), 1, p.5 [Non-Patent Document 4] James E. Mark, Physical Properties of Polymers Handbook 2nd ed., Springer, (2006), p.292-293 [Non-Patent Document 5] The Chemical Society of Japan, Experimental Chemistry Course, 5th Edition, Vol. 4 - Fundamentals IV: Organic Chemistry, Polymer Chemistry, and Biochemistry, (2003), p. 31. [Non-Patent Document 6] Miyagawa, Yasuo et al., Journal of the Fuel Association, 54 (1975), p. 983. [Overview of the Initiative] [Problems that the invention aims to solve] 【0017】 When producing coke for use in blast furnaces and the like by modifying low-grade coal and using the modified low-grade coal as part or all of the raw coal, it is desirable to carry out the low-grade coal modification process and the coke production process simultaneously from the viewpoint of improving productivity. Furthermore, as a coal modifier, it is convenient to use a method of blending or adding a solid substance similar to coal, preferably a powder, to the coal. 【0018】 On the other hand, from the perspective of using cheaper modifiers, a technology is conceivable in which low-grade coal is modified by adding waste plastics, which are polymer compounds, to the coke oven. This would make it possible to carry out the aforementioned low-grade coal modification process and coke production process inexpensively and simultaneously. However, until now, the selection of solid substance modifiers has mainly been done empirically, and there have been few methods for selecting them while considering specific physical properties. If it becomes possible to select modifiers while considering predetermined physical properties, it will be possible to select a modifier that meets the necessary addition conditions in a short time during the addition process, which would be advantageous in terms of cost and manufacturing time. 【0019】 From the above-mentioned perspective, examining the prior art, Patent Document 1 describes how selecting a plastic that leaves fixed carbon during volatilization as an additive, and then adding polyvinyl chloride or bakelite selected according to that selection method to coal and performing carbonization, increases the strength of the resulting coke. However, Non-Patent Document 2 reports that the fluidity of coal decreases with the addition of polyvinyl chloride, making it unlikely that the coke strength would increase. Furthermore, Patent Document 9 describes that adding bakelite (phenol resin) disclosed in Patent Document 1 to coal in a solid state does not increase the coke strength, but that the coke strength improves with an addition method that solidifies it from a liquid state. In other words, it is impossible to select an additive that increases coke strength using the selection method described in Patent Document 1. In addition, Non-Patent Document 2, which investigated the effect of adding various plastics to coal on fluidity, also reported that the addition of plastics to coal does not improve the fluidity of the coal. 【0020】 Patent Document 2 describes a method for producing coke with the required strength by adding waste plastic to coal that has undergone rapid heating treatment. As reported in Non-Patent Document 2, the addition of plastic to coal reduces the strength of the coke. Patent Document 2 is a coke production method that compensates for the decrease in coke strength caused by the addition of such plastic by increasing the fluidity of the coal beforehand through rapid heating treatment. Therefore, it cannot be said that the increase in coke strength is due to the addition of plastic. 【0021】 Patent Document 3 describes adding a heavy tar fraction to coking coal and mixing it, then dry-drying the coking coal mixed with this heavy tar fraction. Although it is a simple process, since liquid tar is used as a modifier, a mixing process using a dedicated mixing container is required. Patent Documents 4, 5, 6, 7, and 9 require coal to be treated in a stage before coke production. Patent Document 8 is a technology for blending solid substances with coal, but in order to use large quantities of modifier, it is necessary to manufacture (synthesize) it, which is costly, and many challenges remain before industrial practical application. Furthermore, the modifiers in Patent Documents 3 to 9 were selected empirically, and there is no description of a selection method based on physical properties, and the description is limited to specific compounds. Thus, the above prior art had many points that needed improvement. 【0022】 The method described in Patent Document 10 has the advantage of high accuracy and short processing time because it calculates specific physical properties and uses them for selection. Furthermore, highly accurate selection results can be expected for compounds whose molecular weight can be accurately determined. On the other hand, when calculating compounds with extremely large molecular weights that are generally expressed using average molecular weight, for example, when selecting a modifier from among polymer compounds, there is a possibility that the physical properties obtained from the calculation may exceed a threshold depending on the molecular structure model used in the calculation, and there have been limitations in obtaining highly accurate evaluation results. 【0023】 This invention has been made in view of the circumstances described above, and its objective is to provide a method for selecting a modifier from a wide range of compounds in a simple manner that can improve the fluidity, a characteristic of coal necessary for producing high-strength coke, and to provide such a modifier. Furthermore, it aims to provide a method for modifying coal using the modifier. [Means for solving the problem] 【0024】 As a result of diligent research, the inventors have identified specific physical properties for selecting a modifier to be added to coal or blended coal used as a coke raw material to improve the fluidity of the coal, and have identified a modifier having those specific physical properties, leading to the completion of the present invention. The gist of the present invention for solving the above problems is as follows. 【0025】 [1] A method for selecting a coal fluidity improving agent, characterized in that a compound is selected as a coal fluidity improving agent if its solubility parameter value δ and the lower of its boiling point or decomposition onset temperature T simultaneously satisfy predetermined threshold ranges. 【0026】 [2] The solubility parameter value δ and the lower of the boiling point or decomposition onset temperature T at a pressure of 1013 hPa are given by the following equations 15.0≧δ≧11.0((cal / cm 3 ) 1 / 2 ) T≧350(℃) The selection method according to [1], wherein a compound that simultaneously satisfies the conditions is selected as the modifier. 【0027】 [3] The solubility parameter value δ and the lower of the boiling point or decomposition onset temperature T at a pressure of 1013 hPa are given by the following equations 15.0≧δ≧11.0((cal / cm 3 ) 1 / 2 ) T≧350(℃) A coal fluidity-improving modifier characterized by containing a compound that simultaneously satisfies the following conditions. 【0028】 [4] A method for reforming coal, characterized by heating a mixture obtained by mixing coal with the reforming agent described in [3] to 350°C or higher. 【0029】 [5] The modification method according to [4], wherein the mixture is used as a raw material for blast furnace coke. 【0030】 [6] The modification method according to [4] or [5], wherein the modifier is nylon 66. 【0031】 [7] A method for producing coke, characterized by producing coke by carbon distillation of a mixture of coal and the modifier described in [3]. 【0032】 [8] The manufacturing method according to [7], wherein the mixture contains 30% by mass or less of the modifier with respect to 100% by mass of the coal. 【0033】 [9] The manufacturing method according to [7] or [8], wherein the modifier is nylon 66. [Effects of the Invention] 【0034】 According to the present invention, a modifier that improves the fluidity of coal can be selected from a wide range of compounds with molecular weights, from low to high, in an extremely simple manner, using the solubility parameter value δ of the compound and the lower of the boiling point or decomposition onset temperature T as indicators. Furthermore, coal used as a raw material for coke can be modified to have a higher maximum fluidity (MF) than when it was acquired. Moreover, it is possible to modify the coal simultaneously when producing coke in a coke oven, achieving coal modification more easily and efficiently compared to conventional technologies. This modification produces an effect similar to securing coal with high maximum fluidity (MF), increasing the freedom in designing the blend of multiple types of coal necessary for producing high-strength coke. In addition, even when using low-grade coal with poor fluidity, it is possible to produce coke of the same quality as coke conventionally produced using high-grade coal, thereby achieving a reduction in coke production costs. [Brief explanation of the drawing] 【0035】 [Figure 1] This graph shows the relationship between the amount of modifier MA-2 added and the logarithm of the maximum fluidity (logMF). [Figure 2] This graph shows the relationship between the amount of modifier MA-2 added and the indirect tensile strength of cylindrical coke. [Figure 3] These are cross-sectional micrographs of coke with and without the addition of the modifier MA-2. [Figure 4] This graph shows the strength (DI150 15) of coke obtained by carbonization of coal to which the modifier MA-2 has been added. [Modes for carrying out the invention] 【0036】 The present invention will be described in detail below. 【0037】 The inventors investigated methods for selecting and modifying coal by adding various solids to improve the fluidity of coal, which is necessary for obtaining high-strength coke, specifically by increasing the maximum fluidity (MF) measured by a Gieseler plastometer. As mentioned above, the maximum fluidity (MF) measured by a Gieseler plastometer is generally used as one of the evaluation indicators for important coal properties that affect the quality of coke. 【0038】 [Method for selecting modifiers] The present invention provides a method for selecting a coal fluidity-improving modifier, characterized by selecting a compound as a coal fluidity-improving modifier in which the solubility parameter value δ (SP value) and the lower of the boiling point or decomposition onset temperature T simultaneously satisfy predetermined threshold ranges. 【0039】 The reason why the selection method of the present invention allows for the selection of compounds that can be used as modifiers based on the solubility parameter value δ (SP value) and the temperature T, whichever is lower, the boiling point or the decomposition onset temperature, is presumed to be as follows. 【0040】 Compounds that can be used as modifiers are presumed to penetrate into the constituent molecules of coal when melted, thereby increasing the bond distance between coal constituent molecules. Therefore, when the modifier and coal soften and melt, the greater their affinity, the easier it is for the modifier molecules to penetrate into the coal constituent molecules, resulting in a more homogeneous mixture. A key feature of this invention is the selection of a modifier such that the solubility parameter value δ(SP value) of the coal and the modifier are close in value, using the solubility parameter value δ(SP value) as an indicator for determining this affinity. In fact, the practical solubility parameter value δ(SP value) of coal is 11.0 (cal / cm³) according to Van Krevelen's formula. 3 ) 1 / 2 Above, 15.0(cal / cm 3 ) 1 / 2 The following applies (Non-Patent Document 3). Compounds whose solubility parameter value δ (SP value) falls within this range are considered to have high affinity with coal and can be selected as modifiers that can be mixed homogeneously. 【0041】 On the other hand, the carbonization temperature used in coke production is generally high, ranging from 1000 to 1300°C. However, the effect of the aforementioned reformer on improving coal fluidity manifests itself in a temperature range of 350°C to 550°C. Therefore, compounds that can be used as reformers must have a boiling point or decomposition onset temperature of at least 350°C at atmospheric pressure of 1013 hPa. If the boiling point or decomposition onset temperature of a reformer is lower than 350°C, these compounds will undergo decomposition and become smaller in molecular weight, preventing them from penetrating the coal's constituent molecules. Even if they can penetrate, the effect of widening the bond distance between coal's constituent molecules will be drastically reduced. If both the boiling point and decomposition onset temperature of a compound are known, the lower of the two temperatures should be designated as T, and that temperature T should be 350°C or higher. If either the boiling point or decomposition onset temperature of a compound cannot be determined, the known temperature should be designated as temperature T. 【0042】 Based on the above perspective, and focusing on the solubility parameter value δ (SP value) and the boiling point or decomposition onset temperature T, we selected a modifier and found that compounds satisfying the following conditions are effective in improving the fluidity of coal. It was previously unknown that compounds with the following characteristics have a coal-modifying effect, and this invention provides a new method for selecting such compounds and a modifier. 【0043】 <boiling point> One example of a boiling point measurement method in this invention is a method of measuring the boiling point by optically detecting bubbles using a boiling point measuring device. The general procedure for measuring the boiling point using this device is shown below. To measure the boiling point (the temperature at which a phase transition from liquid to gas occurs), approximately 100 μL of the compound to be measured is weighed out and sealed in a glass tube. Next, to prevent measurement errors due to overheating of the substance being measured, a slightly smaller capillary is inserted into the glass tube containing the substance, and then the glass tube is placed in the measuring device and the measurement is performed. In the measuring device, the glass tube is heated, and the generation of bubbles is observed as the temperature rises. The generated bubbles reflect light from the light source built into the measuring device and are measured as the frequency of bubble generation, and the temperature at which the bubbles are generated is defined as the boiling point. In the case of high-boiling point compounds, it is also common to measure by lowering the atmospheric pressure inside the measuring device. In that case, the atmospheric pressure is measured using a barometer built into the measuring device, converted to a value under atmospheric pressure (1013 hPa), and the boiling point is calculated. In this invention, the measurement method is not limited to the above-mentioned method, and any known boiling point measurement method such as differential analysis, differential scanning calorimetry, Siwoloboff method, distillation method, or dynamic method (a method of measuring the recondensation temperature using a reflux condenser) may be used. Furthermore, the boiling point at atmospheric pressure (1013 hPa) described in known literature may be used, and if a boiling point at a pressure different from atmospheric pressure is known, it may be converted to the boiling point at atmospheric pressure (1013 hPa) and used. The conversion method is not limited to a specific method, but in this invention, the boiling point conversion diagram described in Non-Patent Document 5 was used to convert to the boiling point at atmospheric pressure (1013 hPa). 【0044】 <Decomposition start temperature> In the selection method of the present invention, when polymer materials or the like are used as candidate modifiers, the boiling point may not be clearly measured even when using the boiling point measurement method described above. In such cases, the decomposition onset temperature may be measured instead of the boiling point and that temperature may be used. An example of a method for measuring the decomposition onset temperature in the present invention is a measurement method using pyrolysis gas chromatography / mass spectrometry (Pyro-GC-MS). In this measurement method, a measurement device consisting of a pyrolysis apparatus, a gas chromatograph (GC), and a mass spectrometer (MS) is used. The polymer material is decomposed into small molecules while the temperature is raised in the pyrolysis apparatus, the various types of decomposed small molecules are separated by column separation using GC, and each separated component is detected by MS to identify the decomposition products associated with the temperature rise. Furthermore, the measurement of the decomposition onset temperature in the present invention is not limited to the method described above, and the decomposition onset temperature may be measured using any known measurement method for decomposition onset temperature, such as the generated gas analysis method (EGA-MS) or the measurement method using a differential thermal-thermogravimetric simultaneous analyzer (TG-DTA). Furthermore, since the gas generated initially after the start of heating is an impurity such as solvent molecules and polymerization initiators that adhered during the synthesis of polymer materials, in this invention, the temperature at which a weight loss equal to 10% of the total weight loss when heating from room temperature to 800°C at a heating rate of 3 to 10°C / min using a thermobalance is observed is defined as the decomposition start temperature. 【0045】 <Solubility parameter values> The solubility parameter value δ (SP value) is a value defined by the regular solution theory introduced by Hildebrand, which is represented by the square root of the cohesive energy density of a solvent or solute, and serves as a criterion for the solubility of a binary solution. As methods for obtaining the solubility parameter value δ (SP value), there are methods of calculating from the heat of vaporization, methods of calculating from the chemical composition, methods of measuring from the compatibility with substances with known solubility parameter values δ (SP value), etc. In the present invention, a value calculated by the calculation method based on the group contribution method described in Non-Patent Document 4, which is an example of the method of calculating from the chemical composition, can be preferably used. In this calculation, Van Krevelen's parameters are used, and when some of Van Krevelen's parameters cannot be obtained, Small's parameters are used for calculation. The density required for the calculation can be a value measured by a known method or a literature value. In addition, the upper and lower limit values of the numerical range in the present invention are included in the equivalent range of the present invention as long as they have the same operational effects as within the numerical range even if they slightly deviate from the numerical range specified by the present invention. 【0046】 The solubility parameter value δ (SP value) of the compound selected as the modifier, for example, considering the solubility parameter value δ (SP value) of coal by Van Krevelen described in Non-Patent Document 3, is 11.0 (cal / cm 3 ) 1 / 2 or more and 15.0 (cal / cm 3 ) 1 / 2 or less is preferable. From the viewpoint of improving viscosity and fluidity, 11.2 (cal / cm 3 ) 1 / 2 or more and 15.0 (cal / cm 3 ) 1 / 2 or less is more preferable, and 11.3 (cal / cm 3 ) 1 / 2 or more and 15.0 (cal / cm 3 )[[ID=燕]] 1 / 2 or less is even more preferable. When the solubility parameter value δ (SP value) is less than 11.0 (cal / cm 3 ) 1 / 2 , or more than 15.0 (cal / cm 3 ) 1 / 2If the compound is larger, the affinity between the coal and the compound is low, making it impossible for the compound molecules to penetrate the coal's constituent molecules, and thus a sufficient additive effect cannot be obtained. 【0047】 <Modifier> An example of a polymer compound that can serve as a modifier satisfying the above parameters of the present invention is one in which the solubility parameter value δ (SP value), calculated using the group contribution method (Non-Patent Literature 4), is 11.0 to 15.0 (cal / cm³). 3 ) 1 / 2 Examples of polyamide resins include those that fall within the specified range and exhibit a decomposition initiation temperature of 350°C, 1013 hPa or higher. Polyamide resins refer to resins formed by the bonding of numerous monomers by amide bonds. Generally, polyamides containing an aliphatic skeleton are collectively called nylon, and polyamides composed solely of an aromatic skeleton are collectively called aramid. Among these, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 46, nylon 6 / 66, nylon 6 / 66 / 12, nylon 6 / 66 / 610, nylon MXD6, nylon 6T, nylon 6 / 6T, nylon 6I, and nylon 9T are preferred as modifiers due to their high fluidity-improving effect. However, as long as the solubility parameter value δ (SP value) and the decomposition initiation temperature are within the numerical range specified by the present invention, the polyamide resins are not limited to those listed herein, and any known compound may be used. 【0048】 Another example of a polymer compound that can serve as a modifier satisfying the above parameters of the present invention is a polymer compound whose solubility parameter value δ (SP value), calculated using the group contribution method formula (Non-Patent Document 4), is 12.39 (cal / cm³). 3 ) 1 / 2Examples include polyacetal resins (polyoxymethylene resins) that exhibit a decomposition initiation temperature of 400°C, 1013hPa. Polyacetal resins are polymers with CH2O (oxymethylene or formaldehyde) as the unit structure (monomer). Among these, examples include homopolymers of formaldehyde alone, and copolymer copolymers in which (CH2O) and (CH2CH2O) are copolymerized in a constant ratio, with about 10 mol% of CH2CH2O (oxyethylene) added as a monomer. Note that any known compound may be used, not limited to the polyacetal resins listed herein, as long as the solubility parameter value δ (SP value) and the decomposition initiation temperature are within the numerical range specified by the present invention. 【0049】 An example of a structure of a low-molecular-weight compound that can serve as a modifier satisfying the above parameters of the present invention is a compound with a solubility parameter value δ (SP value) calculated using the group contribution method (Non-Patent Literature 4) of 11.0 to 15.0 (cal / cm³). 3 ) 1 / 2 Examples include primary or secondary amine compound derivatives, phenothiazine derivatives, carbazole derivatives, indole derivatives, imidazole derivatives, pyrazole derivatives, and other heterocyclic compounds, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, arylamine derivatives, and compounds formed by the combination of multiple such compounds, or polymers having groups made of these compounds in their main chain or side chain. In particular, compounds having an aromatic amine skeleton such as 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N'-diphenyl-1,4-phenylenediamine, N,N',N''-triphenyl-1,3,5-benzenetriamine, N,N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-1,4-phenylenediamine (abbreviated as DNPD), and N-phenyl-1-naphthylamine (abbreviated as NPN) are preferred as modifiers because they have a high fluidity-improving effect. Phenothiazines and carbazoles are also preferred. However, as long as the solubility parameter value δ (SP value) and boiling point are within the numerical range specified in this invention, any known low molecular weight compound may be used, and the invention is not limited to those listed herein. 【0050】 Generally, coal used as a raw material for coke in blast furnaces and the like begins to soften and melt at around 350°C when heated, and its softening and melting temperature range is said to be between 350°C and 550°C. Therefore, among polyamide resins, those with relatively high melting points are thought to be able to melt into the coal when it softens and melts. 【0051】 Furthermore, polyamide resins such as nylon 66, nylon 6, and nylon 6T are used in a variety of applications due to their excellent mechanical properties, heat resistance, and chemical resistance, and are also collected as waste plastics. Therefore, it is also possible to recycle and use such waste polyamide resins that are discharged in large quantities as industrial or general waste. 【0052】 [Methods for reforming coal and producing coke] The following describes an example of an embodiment of the method for modifying coal (method for improving fluidity) and the method for producing coke by adding the modifier according to the present invention. 【0053】 The coal to be modified for fluidity improvement is crushed to a particle size of 5.0 mm or less (below the sieve that has passed through a sieve with a mesh size of 5.0 mm), preferably to a particle size of 5.0 mm or less, and further crushed so that at least 70% by mass of it has a particle size of 3.0 mm or less (below the sieve that has passed through a sieve with a mesh size of 3.0 mm), and the powder (including granular form) of the modifier is mixed with this crushed coal. Multiple modifiers may be added at this time. 【0054】 The mixture of this coal and the powder of the modifier is carbonized at a temperature of 350°C or higher. Coal used for coking in blast furnaces and the like exhibits a fluidity phenomenon when heated to 350°C or higher, and this fluidity is improved by the addition of the modifier. 【0055】 When the modifier is added as a solid substance, such as a powder, there are no particular requirements for its particle size. However, if efficient modification is desired, a smaller particle size is preferable, for example, 10 mm or less is preferable, and 3 mm or less is more preferable. 【0056】 Furthermore, when producing coke by charging a blend of coals of multiple types into a coke oven, one or more powders of the aforementioned modifiers may be added to one or more types of coals of a certain type and then mixed. This mixture of modifiers and coal may then be used as coal constituting the blend in the production of coke. During carbonization in the coke oven, the mixture consisting of the powdered modifiers and coal is heated, and as the heat rises, the fluidity is improved by the modifiers, which react with the other types of coal to produce coke. 【0057】 The carbonization temperature used in coke production is generally high, ranging from 1000 to 1300°C. However, the fluidity-improving effect of the aforementioned modifier manifests itself in a temperature range of 350°C to 550°C, and the coal is sufficiently modified during the heating process of carbonization for coke production. If the purpose is to evaluate only the improvement of coal fluidity by the aforementioned modifier without carbonizing the coal into coke, a carbonization temperature of 350 to 550°C is sufficient. Furthermore, the carbonization time in this case depends on the type of coal, so it can be appropriately determined by conducting evaluation tests using a small amount of the coal whose fluidity is to be improved beforehand. 【0058】 Furthermore, a mixture of other compounds with the modifier may be used as a fluid modifier, provided that it does not inhibit the effect of the modifier. In addition, two or more different types of modifiers may be mixed and used. 【0059】 Other compounds mentioned above may include, for example, waste containing plastics or spare plastics that are discharged in large quantities as industrial or general waste. In this case, the plastics contained in the waste plastics are not particularly limited, but examples include polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). 【0060】 In the coal reforming method according to the present invention, the coal to be reformed is not limited and can include, for example, all coal used as raw material for coke in blast furnaces, such as strongly coking coal and non-coking coal. In this invention, it is practical to target non-coking coal having a small maximum fluidity (MF) value alone, or a blend of several types of non-coking coal. 【0061】 Since the amount of the aforementioned modifier mixed with the coal to be modified is effective even in small amounts, there is no need to set a lower limit. However, since the modification effect tends to be greater with larger amounts, the amount added is preferably 0.01% by mass or more per 100% by mass of the coal to be modified. Furthermore, since amounts exceeding 30% by mass become costly, 0.01 to 30% by mass is preferred, and more preferably 0.2 to 30% by mass. When using a mixture of two or more different types of the aforementioned modifiers, it is sufficient that their total amount falls within the above range. 【0062】 As described above, the modifier may be added in powder form, but the form in which it is added is not particularly limited. For example, the modifier may be added in the form of particles, dissolved in a solvent and added as a solution, or added in slurry form. 【0063】 As described above, according to the present invention, by simply adding the modifier to coal, it is possible to modify the fluidity of coal used as a raw material for coke to a fluidity different from that of the coal at the time of acquisition, that is, to coal with a higher maximum fluidity (MF) value compared to the time of acquisition. Furthermore, it is possible to modify the coal simultaneously with the production of coke in a coke oven, thereby improving the fluidity of the coal and producing high-strength coke more easily and efficiently than conventional methods. [Examples] 【0064】 The present invention will be described in more detail below based on examples. 【0065】 Table 1 below shows the compound names of MA-1 to MA-8, 17, and 18, which are examples of modifiers suitable for the present invention, and MA-9 to MA-16, which are control examples, along with their respective solubility parameter values ​​δ (SP values) calculated using the group contribution method (Non-Patent Literature 4), and the temperature T, whichever is lower, either the boiling point or the decomposition onset temperature, as described in known literature. The following compounds are illustrative examples to make the present invention more specific, and are not limited to the compounds shown in Table 1 as long as they do not depart from the concept of the present invention. Any known compound may be used as long as it does not contradict the spirit of the present invention. 【0066】 [Table 1] 【0067】 As shown in the following examples, when the effect of adding the compounds listed in Table 1 to coal to improve Gieseler fluidity was measured, it was confirmed that compounds that simultaneously satisfy the range of a predetermined solubility parameter value δ (SP value) and the lower of the boiling point or decomposition onset temperature T have the effect of modifying coal. 【0068】 [Example 1] This section describes an example of modifying the fluidity of coal by adding the modifier MA-1 (N,N'-diphenyl-1,4-phenylenediamine). The modifier MA-1 was determined based on a solubility parameter value δ (SP value) calculated using the group contribution method, and the lower of the boiling point or decomposition onset temperature T measured experimentally, which is 15.0 (cal / cm³). 3 ) 1 / 2 ≥δ≧11.0(cal / cm 3 ) 1 / 2 It is a compound that simultaneously satisfies the conditions T≧350(℃,1013hPa). 【0069】 The fluidity-improving effect (modification effect) of the modifier MA-1 added to coal was confirmed by the following procedure. First, coal ground to a particle size of 425 μm or less in accordance with JIS M8801 was mixed with commercially available MA-1 powder (hereafter, for polymers, powder that was freeze-ground to a particle size of 450 μm or less) to prepare a mixed sample of coal and MA-1. At this time, the amount of MA-1 powder mixed with coal was adjusted so that the mass ratio of MA-1 to 100% by mass of coal was 10% by mass. 【0070】 This mixed powder was placed in a designated container according to the Gieseler plastometer method of JIS M8801. This container was then placed in a furnace preheated to 300°C according to JIS M8801, and heated to 550°C at a rate of 3°C / min to raise the temperature of the mixed powder to the softening and melting temperature range of coal. The maximum fluidity (MF) of the coal was measured for this mixed sample in accordance with JIS M8801. 【0071】 In addition, the maximum fluidity (MF) was measured for raw coal without MA-1 mixing (in this embodiment, a single type of coal was used without mixing multiple types, i.e., single-type coal was used). Table 2 shows the logarithmic values ​​(logMF) of the maximum fluidity of the coal used in the reforming test. As shown in Table 2 as "Logarithmic values ​​(logMF) of the maximum fluidity of the raw coal," the logarithmic values ​​(logMF) of the coal used in the reforming test were at most 1.26, indicating that all of the raw coals were low-grade coals with low fluidity that would not be suitable for the production of high-strength coke in their current state. 【0072】 [Examples 2-10] The solubility parameter value δ (SP value) of modifier MA-1, calculated using the group contribution method, and the lower of the boiling point or decomposition onset temperature T, measured experimentally, are 15.0 (cal / cm³). 3 ) 1 / 2 ≥δ≧11.0(cal / cm 3 ) 1 / 2 Except for changing to modifiers MA-2 to MA-8, 17, and 18 shown in Table 1, which simultaneously satisfy T≧350(℃, 1013hPa), the maximum fluidity (MF) was measured in the same manner as in Example 1. 【0073】 [Comparative Examples 1-8] As a comparative example, instead of MA-1, the solubility parameter values ​​δ (SP value) calculated using the group contribution method were δ > 15.0 (cal / cm³). 3 ) 1 / 2 Alternatively, 11.0 (cal / cm³) 3 ) 1 / 2 MA-9 to MA-16, which satisfy the >δ requirement, were added to coal at a concentration of 10% by mass relative to 100% by mass of coal. The maximum fluidity (MF) of these mixed samples was also measured in accordance with JIS M8801. 【0074】 In addition, the maximum fluidity (MF) of raw coal without the additive was also measured, similar to Example 1. The measurement results are shown in Table 2, along with the logarithm of the maximum fluidity of the raw coal (logMF). A positive value for the difference in the logarithm of the maximum fluidity before and after modification (ΔlogMF) indicates "effective," a value of 0 indicates "ineffective," and any other value indicates "deteriorating effect." Furthermore, a result of "unmeasurable" for the maximum fluidity after modification means that no fluidity was observed at all (MF=0ddpm), i.e., fluidity was lost. 【0075】 [Table 2] 【0076】 As shown in Table 2, it was found that adding MA-1 to MA-8, 17, and 18 from Examples 1 to 10 to coal improved fluidity and increased the logarithmic value of maximum fluidity (logMF) in all cases. This indicates that MA-1 to MA-8, 17, and 18 are effective in improving the logarithmic value of maximum fluidity (logMF) regardless of the magnitude of the logarithmic value of maximum fluidity (logMF) of the raw coal. In other words, the improvement in the logarithmic value of maximum fluidity (logMF) indicates that the coal became easier to melt due to the addition of the modifier, and that the coking properties were improved. 【0077】 In contrast, the modifiers MA-9 to MA-16 in Comparative Examples 1 to 8 either did not change the fluidity of the coal, or conversely, caused a deterioration in its fluidity. 【0078】 From the above results, the solubility parameter value δ (SP value) calculated using the group contribution method and the lower of the boiling point or decomposition onset temperature T measured experimentally are 15.0 ≥ δ ≥ 11.0 ((cal / cm²). 3 ) 1 / 2 It was found that a modifier that simultaneously satisfies the conditions of ) and T≧350(℃) has the effect of improving the logarithmic value of the maximum fluidity (logMF) of coal. Furthermore, this modification effect was confirmed even in coal with a logMF higher than the logarithmic value of the maximum fluidity (logMF) of raw coal shown in Table 2, which ranges from 0.48 to 1.26. Therefore, it can be said that the modifier and modification method of the present invention are effective for any type of coal, but in terms of modifying coal with low fluidity, it is particularly effective to add the modifier to coal with a logMF of about 2.3 or less. 【0079】 [Example 11: Amount of modifier added and effect on improving coal fluidity] The solubility parameter value δ (SP value) calculated using the group contribution method and the lower of the boiling point or decomposition onset temperature T measured experimentally, are 15.0 (cal / cm³). 3 ) 1 / 2 ≥δ≧11.0(cal / cm 3 ) 1 / 2This section describes examples of measuring the maximum fluidity (logMF) and measuring the coke strength of the modifier MA-2 (nylon 66), which simultaneously satisfies T≧350(℃,1013hPa), by varying the amount added. For the modification tests, coal with a low maximum fluidity (logMF) of 0.3 or less was used, making it difficult to produce high-strength coke on its own. 【0080】 The effect of adding MA-2 on improving coal fluidity was confirmed by the following procedure. First, coal ground to a particle size of 425 μm or less according to JIS M8801 was mixed with MA-2 to prepare a mixed sample of coal and MA-2. At this time, the amount of MA-2 powder mixed with the coal was adjusted so that the mass ratio of MA-2 to 100% coal mass was 0 (no addition), 0.2, 1, 5, 10, 20, or 30% by mass. Coal A with an MF of 2 ddpm (logMF=0.3) and coal B with an MF of 0 ddpm were used. 【0081】 This mixed powder was placed in a designated container according to the Gieseler plastometer method of JIS M8801. The container containing the mixed powder was then placed in a furnace preheated to 300°C according to JIS M8801 and heated to 550°C at a rate of 3°C / min, thereby raising the temperature of the mixed powder to the coal softening and melting temperature range. The maximum fluidity (MF) of this mixed sample was measured in accordance with JIS M8801. In addition, the maximum fluidity (MF) of raw coal alone, without the addition of MA-2, was also measured. 【0082】 Figure 1 shows the relationship between the amount of MA-2 added and the logarithm of the maximum fluidity (logMF). In Figure 1, when MF is 0 ddpm, the logarithm of the maximum fluidity (logMF) cannot be shown, so for convenience, the position of 0 on the vertical axis is set to log0. Also, in the measurement with an addition rate of 30 mass%, the maximum fluidity (MF) exceeded the upper limit of measurement, 50,000 ddpm, and therefore could not be shown in Figure 1. Therefore, the results are shown only in the range of addition rates from 0 to 20 mass%. Note that in Figure 1, logMF is shown as a constant value in the range of low MA-2 addition rates. This is because measurements are performed in units of 1 ddpm, and differences of less than 1 ddpm cannot be detected. 【0083】 As shown in Figure 1, it was found that adding MA-2 to coal significantly improved its fluidity as the amount of MA-2 added increased. 【0084】 Thus, it was found that applying the present invention makes it easier to select a modifier for improving the fluidity of coal, and that when the selected modifier is actually added to coal and heated, the fluidity characteristics of the coal improve. In other words, the effectiveness of the modifier selection method in the present invention was confirmed. 【0085】 Furthermore, after producing coke using the modifier selected according to the present invention, its strength was confirmed by performing a simple carbonization test (Example 12) and a large-scale carbonization test (Example 13). 【0086】 [Example 12: Measurement of coke strength by simple carbonization test] The simplified carbonization test was conducted using the following procedure. Coal ground to a particle size of 500 μm or less was mixed with MA-2 to prepare a mixed sample of coal and MA-2. At this time, the amount of MA-2 powder mixed with coal was adjusted so that the mass ratio of MA-2 to 100% coal by mass was 0 (no addition), 0.2, 1, 5, 10, 20, and 30% by mass. Coal A and coal B, the same as in Figure 1, were used. 【0087】 A mixture of dried coal and MA-2 (1.0 g, hereafter referred to as "-dry") was filled into a 10 mm diameter mold and subjected to a pressure of 30 MPa for 1 minute to obtain a cylindrical molded product. This molded product was heated to 900°C in an N2 airflow at a heating rate of 3°C / min, and then held for 30 minutes to obtain cylindrical coke. The strength of the obtained cylindrical coke was measured as the indirect tensile strength by applying a load from the side and measuring the pressure at which the coke fractured, referring to Non-Patent Literature 6. 【0088】 The test results are shown in Table 3 and Figure 2. Figure 2 shows the relationship between the amount of MA-2 added and the indirect tensile strength of coke. As shown in Figure 2, the indirect tensile strength improved for both coal A and B from the addition of 0.2 mass%, and increased as the addition rate increased. 【0089】 [Table 3] 【0090】 To determine the effect of MA-2 on coal, cylindrical coke samples prepared with MA-2 added at 0% and 30% by mass were examined using a cross-sectional microscope. The resulting microscopic images are shown in Figure 3. In both coal samples A and B, the coke with 0% MA-2 did not easily melt between coal particles, resulting in most particles having the angular shape characteristic of coal. In contrast, the coke with 30% MA-2 showed almost no angular particles, and most particles exhibited a structure where they were fused together. Considering the amount of MA-2 added to the coal, the amount added is considered too small to interpret this as MA-2 remaining between coal particles after melting, causing them to adhere and solidify. Rather, it is thought that MA-2 penetrated into the coal molecules, modifying the coal and improving its meltability, thus forming the state shown in the microscopic images. 【0091】 [Example 13: Measurement of coke strength by large-scale carbonization test] The large-scale carbonization test was conducted using the following procedure. Coal A (logMF=0.3) ground to a particle size of 3 mm or less was mixed with MA-2 to prepare a mixed sample of coal and MA-2. At this time, the amount of MA-2 powder mixed with coal was adjusted so that the mass ratio of MA-2 to 100% coal mass was 0 (no additive), 2, 5, or 10% by mass. 12.2 kg-dry of the coal-MA-2 mixture was placed in a SUS container at a rate of 750 kg-dry / m³. 3 The mixture was packed to achieve the specified density, then carbonized at 1050°C for 6 hours, followed by cooling in nitrogen to produce coke. The strength of the obtained coke was determined according to the 150 rpm 15 mm index (DI) specified in JIS K2151:2004. 150 15 It was evaluated by ). 【0092】 The test results are shown in Figure 4. Figure 4 shows the relationship between the amount of MA-2 added and the coke strength (DI). 150 15 The relationship between the two is shown. As shown in Figure 4, coke strength increased with increasing MA-2 addition rate. The decomposition start temperature of MA-2 is 450°C, and it is thought that most of it decomposes at the carbonization treatment temperature of 1050°C, but the coke strength increases with the addition of MA-2. Therefore, from these results, it can be concluded that the action of MA-2 is not to adhere coal particles together by melting and remaining between them, but rather that MA-2 reacts with coal to modify the coal, increasing its fluidity, and as a result the coke strength improves. 【0093】 In summary, by applying the present invention, it was confirmed that the selection of a modifier for improving the fluidity of coal becomes easier, and that the selected modifier actually exhibits an effect of improving the fluidity characteristics of coal. In other words, the validity of the modifier selection method in the present invention was confirmed. [Industrial applicability] 【0094】 According to the present invention, a modifier for improving the fluidity of coal can be selected very easily using the solubility parameter value δ (SP value) of the compound and the lower of the boiling point or decomposition onset temperature T as indicators. Furthermore, by simply adding the selected modifier to the coal, the fluidity of the coal used as a raw material for coke can be modified to a different fluidity than when it was acquired, that is, to coal with a higher logarithmic value (logMF) of maximum fluidity compared to when it was acquired. Moreover, it is possible to modify the coal in conjunction with the production of coke in a coke oven, making it possible to improve the fluidity of coal and produce high-strength coke more easily and efficiently than in the past.

Claims

[Claim 1] The solubility parameter value δ and the lower of the boiling point or decomposition onset temperature T at a pressure of 10¹³ hPa are given by the following equations: 15.0≧δ≧11.0((cal / cm ３ ) １／２ ) T ≥ 350 (°C) A method for selecting a coal fluidity-improving modifier, characterized by selecting a compound that simultaneously satisfies the following conditions as a modifier to improve the fluidity of coal. [Claim 2] The solubility parameter value δ and the lower of the boiling point or decomposition onset temperature T at a pressure of 10¹³ hPa are given by the following equations: 15.0≧δ≧11.0((cal / cm ３ ) １／２ ) T ≥ 350 (°C) A coal fluidity improving modifier characterized by containing a compound which is a polyamide resin or polyacetal resin selected from the group consisting of nylon 11, nylon 12, nylon 610, nylon 612, nylon 46, nylon 6 / 66, nylon 6 / 66 / 12, nylon 6 / 66 / 610, nylon MXD6, nylon 6T, nylon 6 / 6T, nylon 6I, nylon 9T, and aramid, which simultaneously satisfies the following conditions. [Claim 3] A method for modifying coal, characterized by heating a mixture obtained by mixing coal with the modifying agent described in claim 2 to 350°C or higher. [Claim 4] The modification method according to claim 3, wherein the mixture is used as a raw material for blast furnace coke. [Claim 5] A method for producing coke, characterized by producing coke by carbon distillation of a mixture of coal and the modifier described in claim 2. [Claim 6] The manufacturing method according to claim 5, wherein the mixture contains 30% by mass or less of the modifier with respect to 100% by mass of the coal.

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