Coke manufacturing method

Abstract

To provide a coke production method that can suppress reaction deterioration of coke caused by metallic oxides originally existing in coal.SOLUTION: A coke production method of the invention in which blended coal containing molded coal and powdered coal is carbonized to produce coke, comprises: determining the ash content in the molded coal and the metal content or metal oxide content in the ash of the molded coal; determining the ash content in the powdered coal and the metal content or metal oxide content in the ash of the powdered coal; and carbonizing the blended coal in which the metal content or metal oxide content in the molded coal and the powdered coal has been adjusted so that CAshbq (mass%) calculated from the determined ash content and metal content or metal oxide content in the molded coal is greater than CAshp (mass%) calculated from the determined ash content and metal content or metal oxide content in the powdered coal.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for producing coke, in which a coal blend containing briquetted coal produced by briquetting coal and unbriquette powdered coal is charged into a coke oven and carbonized. [Background technology]

[0002] For efficient operation of a blast furnace, it is preferable to use high-strength coke. This is because, when coke breaks down in the blast furnace, the resulting fines reduce the permeability of the blast furnace, making efficient operation difficult. Furthermore, coke becomes porous and brittle when it reacts with CO2 in the blast furnace. In other words, as the amount of coke reacted in the blast furnace increases, the strength of the coke after reaction decreases, so high strength after reaction with CO2 (hereinafter referred to as "post-reaction strength") is required.

[0003] In recent years, there has been a demand to reduce CO2 emissions in response to global warming. Therefore, reducing the amount of coke used in blast furnace operation is important for reducing CO2 emissions in the steel industry. The amount of coke consumed per ton of molten iron produced is called the coke ratio, and it has been reported that the higher the coke's post-reaction strength, the lower the coke ratio.

[0004] One known method for increasing coke's post-reaction strength is to reduce the amount of coke reacted with CO2 to prevent coke weakening due to its reaction with CO2 (hereinafter referred to as "coke deterioration"). For example, metal components (ash) present in coke are known to act as catalysts, promoting the reaction between the carbonaceous material in the coke and CO2 gas. Therefore, a known method is to reduce the amount of catalytic metal components, thereby reducing the amount of reaction with CO2 and preventing coke deterioration due to the reaction. To reduce the metal content in coke, coal with a low metal content is typically used. However, because the metal components in coal are contained in the inorganic components (components that become ash) of coal, removing the inorganic components from mined coal requires costs, making coal with a low metal content expensive. Another problem with coal with a low metal content is that its resources are limited.

[0005] Another method for preventing coke from reacting with CO2 is to make it less susceptible to a decrease in strength after the reaction. This method has been investigated as a technology for obtaining highly reactive and strong coke. Specifically, a method has been developed in which metal components that promote the reaction are added to coal to increase its reactivity with CO2, while suppressing the weakening of the coke due to increased reactivity and reinforcing the weakened areas.

[0006] Patent Document 1 discloses a method in which granules made by mixing catalytic metal and coal are prepared in advance, and the granules are added to powdered coal and carbonized to promote a reaction in the part of the granules where the added catalytic metal is concentrated, while maintaining the strength of the coke without promoting the reaction in the part where the catalytic metal has not been added.

[0007] Patent Document 2 also discloses a method for obtaining coke by preparing granules (pseudo-particles) with a core containing a mixture of catalytic metals that promotes gasification reactions and a high-strength material (pore wall reinforcement material) arranged on the outside, and then adding the granules to coal and carbonizing them. This method is based on the idea that the gasification reaction occurs mainly in the core of the granules, while providing a structure that maintains strength, thereby maintaining the strength of the coke after the reaction. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-232348 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-147370 Summary of the Invention [Problem to be solved by the invention]

[0009] Prior art has disclosed a method of actively adding catalytic metals to a coal blend to promote the gasification reaction of coke. However, no progress has been made in developing a method for suppressing reaction deterioration caused by catalytic metals originally present in coal, or a method for producing coke that can maintain strength after the reaction even when coal with a high catalytic metal content is used.

[0010] The method disclosed in Patent Document 1 is a technology that can maintain the post-reaction strength of coke even when the catalytic metal content is high. However, it is characterized by the active addition of catalytic metal to coal to make the catalytic metal concentrated. Therefore, it cannot be applied to the production of conventional coke when coal originally contains a high catalytic metal. Furthermore, it is not possible to confirm whether the method disclosed in Patent Document 1 can reduce the reaction deterioration of coke caused by the catalytic metal originally present in the coal. Furthermore, in the examples of Patent Document 1, there are cases where the post-reaction strength is lower than that of conventional coke when no catalytic metal is added. This suggests that the addition of catalytic metal may make it impossible to maintain coke strength. In other words, the method of Patent Document 1, which aims to produce high-reactivity coke, cannot be directly applied to solve the problem of reaction deterioration when producing conventional coke.

[0011] The method disclosed in Patent Document 2 is based on the technical idea of ​​using a high-strength raw material to suppress a decrease in strength after the reaction due to increased reactivity. For this reason, it is unsuitable as a method for producing ordinary coke using coal that originally contains a high amount of catalytic metals.

[0012] On the other hand, if coal (powdered coal) pulverized by a conventional method is simply carbonized without using the methods disclosed in Patent Documents 1 and 2, the reaction degradation of the coke is significantly affected by the catalytic metals contained in the coal, making it difficult to suppress the reaction degradation.

[0013] The present invention has been made in view of the above circumstances, and aims to provide a method for producing coke that can suppress the reaction deterioration of coke caused by metal oxides originally present in coal. [Means for solving the problem]

[0014] The gist and configuration of the present invention to solve the above problems are as follows. [1] A method for producing coke by dry distilling a coal blend containing briquettes and powdered coal, the method comprising: determining an ash content in the briquettes and a metal content or a metal oxide content in the ash of the briquettes; determining an ash content in the powdered coal and a metal content or a metal oxide content in the ash of the powdered coal; and calculating a CAsh from the determined ash content and the metal content or the metal oxide content in the briquettes. bq (mass%), and CAsh calculated from the ash content and the metal content or the metal oxide content in the obtained powdered coal. p A method for producing coke, comprising carbonizing a coal blend in which the metal content or the metal oxide content in the molded coal and the powdered coal has been adjusted so that (mass%) satisfies the following formula (1): Cash bq (mass%)>CAsh p (mass%)...(1) Here, CAsh bq (mass%) is calculated using the following formula (6), and CAsh p (mass%) is calculated using the following formula (4): Cash bq (mass%)=Ash bq (mass%)×(a×Na2O bq (mass%)+b×K2O bq (mass%)+c×CaO bq (mass%)+d×MgO bq (mass%)+e×Fe2O 3bq (mass%)) / 100 (6) Cash p (mass%)=Ash p (mass%)×(a×Na2O p (mass%)+b×K2O p (mass%)+c×CaO p (mass%)+d×MgO p (mass%)+e×Fe2O 3p (mass%)) / 100 (4) Ash bq (mass%) is the ash content in the briquettes, p(mass%) is the ash content in the powdered coal, NaO bq (mass%) is the NaO content in the ash of the molded coal, p (mass%) is the NaO content in the ash of the powdered coal, bq (mass%) is the K2O content in the ash of the molded coal, p (mass%) is the K2O content in the ash of the powdered coal, CaO bq (mass%) is the CaO content in the ash of the molded coal, and CaO p (mass%) is the CaO content in the ash of the powdered coal, MgO bq (mass%) is the MgO content in the ash of the molded coal, MgO p (mass%) is the MgO content in the ash of the powdered coal, and FeO 3bq (mass%) indicates the Fe2O3 content in the ash of the molded coal, and a, b, c, d, and e indicate the ash content of the powdered coal, the amounts of Na2O, KO, CaO, and MgO in the ash, with the post-reaction strength or reactivity of the coke after carbonization of the powdered coal as the objective variable. 、 This is a coefficient determined by multiple regression analysis using the Fe2O3 content as an explanatory variable. [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress the reactive deterioration of coke caused by metal oxides originally present in coal. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a graph showing the results of coke reactivity and post-reaction strength relative to the limestone content. [Figure 2] FIG. 1 shows the correlation between CAshp and post-reaction intensity. [Figure 3] FIG. 1 shows the relationship between ΔCAsh values ​​and reactivity (CRI) or post-reaction strength (CSR). DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, the present invention will be described through embodiments of the present invention.

[0018] To achieve the above objective, the inventors focused on the molded coal blending method. The molded coal blending method involves blending and kneading a portion of the coal used as coke raw material with a binder, then mechanically compacting the blended coal to form molded coal. The molded coal is then charged into a coke oven together with unmolded powdered coal (hereinafter referred to as "powdered coal") for carbonization. By adopting the molded coal blending method, the cold strength of the coke can be maintained even when a large amount of relatively inexpensive, low-caking, non- or slightly caking coal unsuitable for coke production is used. This effect is achieved by pre-molding a portion of the coal, thereby reducing the distance between coal particles in the molded coal, and allowing coal particles to adhere to each other even in low-caking coal. The molded coal blending method is similar to the methods disclosed in Patent Documents 1 and 2 in that a portion of the coal is agglomerated and then carbonized. However, the methods disclosed in Patent Documents 1 and 2 obtain agglomerates by pseudo-particle formation or granulation, and do not involve consolidation. Since the gas diffusion state in the agglomerates differs between granulation and compaction, it is thought that the reactivity after coke formation also differs. However, the influence of this difference in reactivity has not been investigated in the past.

[0019] Therefore, the present inventors conducted extensive research into the influence of the catalytic metal content in the briquettes and powdered coal on the post-reaction strength and reactivity of coke produced from a coal blend produced by the briquetted coal blending method. As a result, it was found that when metals are added to the briquettes, the effect of increasing the reactivity of the coke and the effect of decreasing the post-reaction strength are both smaller than when metals are added to the powdered coal. The present invention is based on this discovery.

[0020] <Reactivity and post-reaction strength of coke when catalytic metals are added in large amounts to molded coal> We investigated the effect of Ca, an example of a catalytic metal that promotes coke reactivity, on the reactivity of coke when it is contained in molded coal and powdered coal. In the investigation, limestone (CaCO3) was used as Ca, and molded coal and powdered coal containing limestone at various ratios were prepared, and the effect of Ca on the reactivity and post-reaction strength of the coke obtained by carbonization was investigated.

[0021] The powdered coal was prepared by blending multiple brands of coal. The quality of the powdered coal was the same as that of the raw coal commonly used in coke production: Ro = 1.02 (%), logMF = 2.40 (logddpm), and Ash = 9.5 (mass%). The particle size of the powdered coal was adjusted so that the proportion of powdered coal with a particle size of less than 3 (mm) was 80 (mass%) and the proportion of powdered coal with a particle size of 3 (mm) to 10 (mm) was 20 (mass%). The moisture content of the powdered coal was adjusted to 8 (mass%) before carbonization testing. Here, Ro is the average maximum vitrinite reflectance of the coal determined by the method of JIS M8816:1992, logMF is the common logarithm of the Gieseler maximum fluidity (MF) determined by the method of JIS M8801:2008, and Ash is the ash content of the coal determined by the method of JIS M8812:2006.

[0022] Here, "ash" is generally defined as the residue remaining after coal combustion, and its amount is determined according to "JIS M8812:2006" and corresponding national and international standards. Coal contains mineral matter, sometimes called gangue. During coal combustion, this mineral matter decomposes and oxidizes to form oxides, and the oxidation products of the remaining mineral matter that remain untouched constitute the main component of ash. Metal components in coal are contained both in the mineral matter and in the organic matter of coal, and most of the metal components are converted to metal oxides during combustion (also known as incineration). Since almost no metal components in coal are lost during carbonization, coal-derived metal components remain in coke. Furthermore, some metal components remaining in coke are known to have catalytic properties that promote the reaction of coke with gases such as CO2 (coke gasification). Because quantifying the metal components in coal or coke is difficult due to the difficulty of quantifying minerals that exist in various forms, it is common to quantify the content of metal oxides produced by the combustion (ashing) process. The metal oxides in ash can be quantified by measuring the content of the metal oxide itself, or by measuring the content of the metal itself and then determining the amount of the oxide when the metal is oxidized. In the present invention, the amount of metal oxides contained in ash was used as an index of the amount of metal components in coal, and the effect on the coke gasification reaction was investigated.

[0023] Briquette coal was produced by the following procedure. The coal used to produce the briquette coal was a briquette coal blend adjusted to have Ro = 0.92 (%), logMF = 2.4 (logddpm), and Ash = 9.5 (mass%). The briquette coal blend was adjusted so that the proportion of powder coal with a particle size of less than 2 (mm) was 100 (mass%). The limestone to be mixed into the briquette coal blend was adjusted so that the proportion of limestone with a particle size of less than 1 (mm) was 100 (mass%). Then, the briquette coal blend and limestone were mixed in a predetermined ratio, and then binders (2 (mass%) of coal tar pitch, 3.6 (mass%) of soft pitch, and 2.4 (mass%) of asphalt pitch relative to 100 (mass%) of coal) were added (externally added), and the mixture was thoroughly kneaded in a kneader to obtain a kneaded product. The kneaded product was then molded in a high-pressure molding machine equipped with a 6cc egg-shaped mold.

[0024] The limestone content in the blended coal, which is a combination of briquettes and powdered coal, was varied from 0 to 9 (mass%), and a level where limestone was blended only in the powdered coal and a level where limestone was blended only in the briquettes were set. The blending ratio of briquettes to powdered coal was set to 80 (mass%) and 20 (mass%). The blended coal, which is a combination of powdered coal and briquettes, was set to a bulk density of 830 (kg-dry / m 3 The coke was charged into a stainless steel can so that the coke had a uniform particle size (CRI) of 19-21 mm, heated to a wall temperature of 1200°C for 20 hours, and cooled under a nitrogen atmosphere to obtain coke. The obtained coke was adjusted to a particle size of 19-21 mm and subjected to a CO2 reactivity index (CRI) and a CO2 post-reaction strength test (CSR). The CO2 reactivity index (CRI) and CO2 post-reaction strength test (CSR) were measured according to methods compliant with ISO18894:2006. Here, the results obtained from the CO2 reactivity test correspond to the "reactivity" of the coke. The results obtained from the CO2 post-reaction strength test correspond to the "post-reaction strength" of the coke.

[0025] Figure 1 shows the results of the relationship between the reactivity and post-reaction strength of coke and the limestone content. As shown in Figure 1, when limestone is added to powdered coal, as previously known, the reactivity increases (see Figure 1(a)) and the post-reaction strength decreases (see Figure 1(b)) as the limestone content increases. On the other hand, when limestone is added to molded coal, there is almost no increase in reactivity or decrease in post-reaction strength, even if the limestone content is increased.

[0026] Here, in the method of adding a catalytic metal such as Ca to the granules (Patent Document 1), the reactivity tended to increase as the catalytic metal was added. In contrast, as shown in the results in Figure 1, it was revealed that the reactivity of coke did not increase in the method of adding a catalytic metal to molded coal. This difference is attributed to the fact that molded coal is produced by compressing and molding, which increases the density and does not promote reactivity such as gasification reaction.

[0027] Specifically, in Patent Document 1, the density of the catalyst component concentrated portion of the granules, i.e., the portion of the particles containing the catalyst metal, is 0.7 to 1.0 (g / cm 3 ) (see paragraph 0060 of the specification of Patent Document 1). Therefore, it is considered that the porosity of the catalyst component concentrated portion of the coke after carbonization is also sufficiently high to allow gas to easily reach the metal.

[0028] However, the density of briquetted coal is approximately 1.1 (g / cm 3 ) or more. Therefore, in the molded carbon, the porosity is locally low even after carbonization, making it difficult for gas to reach the catalytic metal, and it is thought that the reactivity was not promoted as shown in Figure 1. In other words, it has become clear that the mechanism of deterioration due to the gasification reaction is different between the low-density granulated material described in Patent Document 1 and the high-density molded material.

[0029] <Contribution of catalytic metals (metal oxides) to gasification reactions> As described above, considering the results of tests conducted when catalytic metals were incorporated into coal, it was suggested that coal with a high catalytic metal content, when incorporated in greater amounts into molded coal than into powdered coal, may not promote reactivity due to the gasification reaction and may be less likely to experience a decrease in strength after the reaction.

[0030] However, because calcium is not the only catalytic metal originally contained in coal, it is desirable to quantitatively understand the effect based on the catalytic metal content in coal. Therefore, we investigated the relationship between catalytic metals (metal oxides) in coal and the strength of coke after reaction.

[0031] First, the ash content (ratio) and catalytic metal (metal oxide) content (ratio) of each brand of coal used in coke production were analyzed, and the relationship between the ash content in the coal blend and the strength of the coke after reaction was investigated. Note that the investigation was conducted on coal blends that did not contain molded coal (coal blends containing only powder coal).

[0032] The catalytic metals (composition) in the ash were investigated assuming that all of the catalytic metals in the ash had been converted to metal oxides. Then, a multiple regression analysis was performed on the relationship between the content (ratio) of metal oxides contained in the blended coal and the post-reaction strength of the coke to investigate the type and degree of influence of metal oxides that have a large effect on the post-reaction strength. As a result, Na, K, Ca, Mg, and Fe were extracted as the types of metals that have a large effect on the post-reaction strength, and the post-reaction strength of the coke was calculated using CAsh, which is calculated by the following formula (3): p Figure 2 shows the correlation between CAsh and p The correlation between the strength after reaction and the mass % of the sample is shown. Cash p =Ash p ×(a×Na2O p +b×K2O p +c×CaO p +d×MgO p +e×Fe2O 3p ) ···(3)

[0033] Here, Ash p is the ash content in the powdered coal, Na2O p is the Na2O content in the ash of the powdered coal, and K2O p is the K2O content in the ash of the powdered coal, and CaO p is the CaO content in the ash of the powdered coal, and MgO p is the MgO content in the ash of the powdered coal, and Fe2O 3p means the Fe2O3 content in the ash of the fine coal.

[0034] Cash p is the ash content of coal (powdered coal) p The value is calculated by multiplying the content of each metal oxide of the catalytic metal in the ash by the coefficients (a to e) that represent the magnitude of the influence on the strength of the coke after the reaction. p Ash p This can be said to be a corrected value that reflects the effect of metal oxides in the ash on strength after reaction.

[0035] Also, CAsh p The unit is Ashp In this case, Ash is expressed as mass%. p When the content of each metal oxide in the ash is expressed in mass %, formula (3) can be expressed as formula (4) below. Cash p (mass%)=Ash p (mass%)×(a×Na2O p (mass%)+b×K2O p (mass%)+c×CaO p (mass%)+d×MgO p (mass%)+e×Fe2O 3p (mass%)) / 100 (4)

[0036] In equation (4), Ash p (mass%) is the ash content of the powdered coal, Na2O p (mass%) is the Na2O content in the ash of the powdered coal, and K2O p (mass%) is the K2O content in the ash of the powdered coal, and CaO p (mass%) is the CaO content in the ash of the powdered coal, MgO p (mass%) is the MgO content in the ash of the powdered coal, and FeO 3p (% by mass) means the Fe2O3 content in the ash of the fine coal. All contents are based on mass.

[0037] Cash p (mass%) is the ash content of coal (powdered coal) p (mass%) by the sum of the contents of each metal oxide of the catalytic metal in the ash multiplied by coefficients (a to e) that represent the magnitude of the influence on the strength of the coke after reaction. p (mass%) is the ash of powdered coal p (mass%), it can be said that this is a corrected value that reflects the influence of metal oxides in the ash on strength after reaction.

[0038] The constants a, b, c, d, and e in equations (3) and (4) are coefficients determined by multiple regression analysis. In multiple regression analysis, first, the post-reaction strength of the coke obtained by carbonizing a coal blend (pulverized coal) having various ash compositions (metal oxides) is measured. Then, the measured post-reaction strength is used as the objective variable, and the ash content (ratio) of the coal blend (pulverized coal), the metal oxides in the ash, Na2O, KO, CaO, MgO, etc., are used as the objective variable. 、 The analysis can be performed using the content (rate) of Fe2O3 as an explanatory variable. As a result of the multiple regression analysis, a multiple regression equation in the form of equation (3) or (4) is obtained, and a, b, c, d, and e can be determined as coefficients corresponding to each variable in the multiple regression equation. In addition, Ash, which is obtained by expanding equations (3) and (4) as explanatory variables, can be determined. p ×Na2O p , Ash p ×K2O p , Ash p ×CaO p , Ash p ×MgO p , Ash p ×FeO 3p The post-reaction strength of coke has a strong correlation with the reactivity of coke. Therefore, multiple regression analysis may be performed using the reactivity of coke as the objective variable, and the obtained coefficients may be converted using the correlation between the post-reaction strength and the reactivity to determine the constants a, b, c, d, and e in equations (3) and (4).

[0039] Here, the CAsh shown in Figure 2 p The correlation between the ash content (mass%) and the post-reaction strength (CSR) is shown as a result of an investigation of a coal blend (powdered coal) that does not contain briquettes. When briquettes are included in a coal blend, the constants a, b, c, d, and e may be calculated by multiple regression analysis using the ash content (ratio) and metal oxide content (ratio) of the coal blend (powdered coal only) that does not contain briquettes and the post-reaction strength or reactivity of the coke. This is based on the fact that, as shown in Figure 1, the ash content of briquettes has almost no effect on the post-reaction strength or reactivity of the coke, whereas the ash content (ratio) and metal oxide content (ratio) of the coal blend (powdered coal) that does not contain briquettes have a significant effect.

[0040] As shown in formula (3) and formula (4), the inventors have synthesized five types of metal oxides (NaO, KO, CaO, MgO 、 It was found that the content (rate) of Fe2O3 has a significant effect on the strength and reactivity of the coke after reaction. Therefore, as long as the metal oxides of these catalytic metals are included in the formula, CAsh p or CASh p In order to calculate the mass % of the catalyst, the formula may further include metal oxides of other catalyst metals.

[0041] <Method for producing coke that suppresses reaction deterioration due to metal oxides> As mentioned above, when metal oxides that catalyze the gasification reaction of coke are present in the briquettes, they do not promote the deterioration of the coke reaction. Therefore, by adjusting the amount of metal oxides that cause the deterioration of the coke reaction to be more in the briquettes than in the powdered coal, the deterioration of the coke reaction can be suppressed. In other words, the CAsh calculated by the formulas (3) and (4) can be calculated as follows: p or CASh p It is advisable to adjust the value (mass%) so that the value calculated based on the metal oxide content (rate) in the molded coal is larger than the value calculated based on the metal oxide content (rate) in the powdered coal.

[0042] Specifically, the adjustment is performed as follows. First, for metal oxides that catalyze the gasification reaction of coke, the magnitude of the influence of each metal oxide on the deterioration of the gasification reaction is determined. Specifically, a coal blend containing multiple coals with different compositions (metal oxides) is prepared, and the post-reaction strength or reactivity of the coke obtained by carbonizing the coal blend is measured. Then, a multiple regression analysis is performed using the ash content (ratio) of the portion of the coal blend that does not contain briquettes (a coal blend consisting only of powder coal) and the metal oxide content (ratio) in the ash as explanatory variables, and the post-reaction strength or reactivity of the coke as the response variable, to determine the coefficients of the regression equation (coefficients a to e in equations (3) and (4)).

[0043] In calculating the coefficients of the regression equation, the ash content (rate) and the metal oxide content (rate) in the ash may be determined by collecting and analyzing coal from a portion of the coal blend that does not contain briquettes (a coal blend consisting of only powder coal). Alternatively, a weighted average may be calculated based on the blending ratio of each brand of coal that constitutes the powder coal from the ash content (rate) and the content (rate) of the metal oxide composition in the ash of each coal in the portion of the coal blend that does not contain briquettes (a coal blend consisting of only powder coal). In this way, for example, CAsh p =Ash p ×(a×Na2O p +b×K2O p +c×CaO p +d×MgO p +e×Fe2O 3p ) to find a form like (formula (3) or (4)).

[0044] Here, the composition (metal oxides) of the ash may be determined by burning coal to incinerate it while burning and removing organic matter contained in the coal, quantifying the content (ratio) of each metal in the incinerated coal using a known method, and converting it into a metal oxide state. Alternatively, the metal oxide content may be quantified. Examples of analytical methods include "JIS M8815:1976 Analysis Method for Coal Ash and Coke Ash" and a method for quantifying metal oxides using fluorescent X-ray analysis.

[0045] Next, we will look at the CASh of molded coal, which is the raw material for coke production. bq , and CASh of powdered coal p Cash of powdered coal p can be calculated using formula (3). p When expressed in mass%, it can be calculated using formula (4). bq The CAsh of briquettes can be calculated using the following formula (5). bq When expressed in mass %, it may be calculated using the following formula (6). Cash bq =Ash bq ×(a×Na2O bq +b×K2O bq +c×CaObq +d×MgO bq +e×Fe2O 3bq ) ···(5) Cash bq (mass%)=Ash bq (mass%)×(a×Na2O bq (mass%)+b×K2O bq (mass%)+c×CaO bq (mass%)+d×MgO bq (mass%)+e×Fe2O 3bq (mass%)) / 100 (6)

[0046] Here, in equation (5), Ash bq is the ash content in the briquettes, Na2O bq is the Na2O content in the ash of the briquette, and K2O bq is the K2O content in the ash of the briquette, and CaO bq is the CaO content in the ash of the briquette, and MgO bq is the MgO content in the ash of the briquette, and FeO 3bq means the Fe2O3 content in the ash of the briquette.

[0047] Also, in equation (6), Ash bq (mass%) is the ash content in the briquettes, Na2O bq (mass%) is the Na2O content in the ash of the briquette, and K2O bq (mass%) is the K2O content in the ash of the briquette, and CaO bq (mass%) is the CaO content in the ash of the briquette, and MgO bq (mass%) is the MgO content in the ash of the briquette, and FeO 3bq (% by mass) means the Fe2O3 content in the ash of the molded coal. All contents are based on mass.

[0048] Cash bq is the ash content of the briquettes. bq The value is calculated by multiplying the content of each metal oxide of the catalytic metal in the ash by the coefficients (a to e) that represent the magnitude of the influence on the strength of the coke after the reaction.bq Ash of molded charcoal bq It can be said that this is a value corrected to reflect the effect of metal oxides in the ash on the strength after reaction. However, as mentioned above, the effect on the strength after reaction is the effect when powder coal is blended with this composition. In blending molded coal, as shown in Figure 1, the content of catalytic metal components (CAsh bq ) does not affect the post-reaction strength.

[0049] Cash bq (mass%) is the ash content of the briquettes. bq (mass%) by the sum of the contents of each metal oxide of the catalytic metal in the ash multiplied by coefficients (a to e) that represent the magnitude of the influence on the strength of the coke after reaction. bq (mass%) is the ash content of the briquette bq (mass%), it can be said that this is a corrected value that reflects the influence of metal oxides in the ash on strength after reaction.

[0050] In this case, the ash content (rate) and the metal oxide content (rate) in the ash of the briquettes and pulverized coal may be calculated from values ​​obtained by actual measurements. Alternatively, they may be calculated by a weighted average or other calculation, taking into account the blending ratio of the coal, from the ash content (rate) and the metal oxide content (rate) in the ash of the coal, etc. used for the briquettes and pulverized coal.

[0051] Then, CAsh calculated using equations (3) and (5) bq and CAsh p The type and blending ratio of coal, etc. may be determined so as to satisfy the relationship of the following formula (2), and the briquetted coal and pulverized coal may be produced and mixed to obtain a blended coal, which may be charged into a coke oven and carbonized. bq and CAsh p A coal blend in which the metal content or the metal oxide content in the briquettes and powdered coal has been adjusted so as to satisfy the relationship in formula (2) may be carbonized. Cash bq >Cash p ···(2)

[0052] Or, CAsh bq and CAsh p When expressed in mass%, CAsh calculated using formulas (4) and (6) is bq (mass%) and CAsh p The type and blending ratio of coal, etc. may be determined so as to satisfy the relationship of the following formula (1) with respect to the amount of coal (mass%). Briquettes and powdered coal may be produced and mixed together to obtain a blended coal, which may then be charged into a coke oven and carbonized. bq (mass%) and CAsh p A coal blend in which the metal content or the metal oxide content in the briquettes and powdered coal has been adjusted so as to satisfy the relationship of formula (1) with respect to (mass %) may be carbonized. Cash bq (mass%)>CAsh p (mass%)...(1)

[0053] By adjusting the coal blend to satisfy the above-mentioned formula (1) or (2), it is possible to produce coke that undergoes less reaction degradation than when coke is produced by blending molded coal and powdered coal so that the ash content (ratio) and the metal oxide content (ratio) in the ash are the same.

[0054] The coke production method according to the present invention can suppress the reaction degradation of coke caused by metal oxides originally present in coal. As a result, even when coal containing a large amount of catalytic metal (metal oxide) is used, the reaction degradation of coke can be suppressed, and coke with high strength after reaction can be produced. Furthermore, the amount of coal with a high content of catalytic metal (metal oxide) can be increased compared to conventional methods, thereby expanding the range of coals that can be used as coke raw materials.

[0055] In the above embodiment, the content (rate) of ash and catalytic metal (metal oxide) in coal is described. However, the content (rate) of ash and catalytic metal (metal oxide) in coke after carbonization is described. bq , CAsh p , CAshbq (mass%), CAsh p Alternatively, the metal oxide content (rate) in the ash content may be used for calculation as the metal content or metal content ratio.

[0056] Because coal loses volatile matter through carbonization, there is a correlation between the ash content of the coal and the ash content of the coke in terms of post-reaction strength and reactivity. However, the amount of volatile matter that escapes varies depending on the operating conditions of the coke oven, and the ash content (ratio) of the coke fluctuates. Furthermore, in order to determine the type and blending ratio of coal to be blended into the briquettes and pulverized coal, it is convenient from an operational standpoint to determine the blending ratio based on the ash content of the coal. For this reason, in this embodiment, the conditions for the ash content of the coal are set so as to satisfy the relationship between equations (1) and (2).

[0057] The coal used in the present invention can be any type, and deterioration due to the gasification reaction can be suppressed. Methods other than roll molding can also be used to obtain molded coal, and it is preferable that the method be capable of compacting the coal. To improve the moldability of coal, binders such as water, coal-based binders (coal tar pitch, solvent-refined coal, tar, tar slag, etc.), petroleum-based binders (asphalt, asphalt pitch, propane-deasphalted asphalt, etc.), and organic binders (starch, molasses, resin, etc.) may be used. Furthermore, powdered coke, oil coke, plastics, caking agents (pitches, solvent-refined coal, etc.), biomass, and charcoal obtained by heat treatment of biomass may also be used as part of the molded coal and powdered coal.

[0058] The proportion of briquettes in the coal blend charged into a coke oven is preferably 50% or less as the proportion of briquettes. If the proportion of briquettes exceeds 50%, problems arise in terms of the cost of briquetting. On the other hand, if the proportion of briquettes is too small, the effect of adjusting metals or metal oxides by concentrating highly reactive components in the briquettes becomes small. Therefore, the proportion of briquettes in the coal blend is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 35% by mass or less.

[0059] There is no need to impose any restrictions on the size of the briquettes, and for example, briquettes with a volume of 6 to 120 cc may be used. In consideration of the amount of coke produced and the strength of the briquettes, it is particularly preferable that the size of the briquettes be in the range of 25 to 80 cc.

[0060] Furthermore, the coke production conditions to which the present invention is applied are not limited and can be widely applied. The coal pretreatment process may include some or all of the steps of pulverization, classification, mixing, kneading, drying, hydration, preheating, etc. The pulverized coal may be pulverized so that the proportion of particles of 3 mm or less is 70 to 100%. The carbonization conditions may be a temperature of approximately 900°C or higher using a general chamber-type coke oven. [Example]

[0061] Below, examples carried out using the coke manufacturing method according to this embodiment will be described.

[0062] In the examples, tests were carried out to suppress the reactive deterioration of coke under conditions in which molded coal containing coal containing a large amount of highly reactive metal components was used.

[0063] The ash content and metal oxide content of each brand of coal were analyzed in advance. The powdered coal used was raw coal typically used in coke production, with a quality of Ro = 1.050 (%) and logMF = 2.468 (ddpm / log). After air-drying, the coal was adjusted so that the proportion of powdered coal with a particle size of less than 3 (mm) was 80 (mass%), the proportion of powdered coal with a particle size of 3 (mm) to 10 (mm) was 20 (mass%), and the moisture content was adjusted to 8 (mass%) before use in the test.

[0064] Briquette coal was produced using the following procedure. Coal blends were used for briquette coal, with blending ratios varied within the ranges of Ro = 0.99 to 1.07 (%) and logMF = 2.13 to 2.79 (ddpm / log). The briquette coal blend was adjusted so that the proportion of powder coal with a particle size of less than 3 (mm) was 100 (mass%). After preparing the briquette coal blend, a binder (4.0 (mass%) of coal tar medium pitch, 0.5 (mass%) of soft pitch, and 6.0 (mass%) of tar, relative to 100 (mass%) of coal) was added (externally added), and the mixture was thoroughly kneaded in a kneader to obtain a blend. The blend was then molded in a small molding machine equipped with a 44 mm Massek mold. The density of the obtained briquette coal was 1.12 (g / cm 3 The blending ratio of powder coal to briquette coal was 80 (mass%) and 20 (mass%) of powder coal to briquette coal. The bulk density of the entire sample including powder coal and briquette coal was 810 (kg-dry / m 3 The mixture was charged into a stainless steel carbonization vessel so that the temperature reached 1050°C, and heated for 6 hours in an electric furnace with the furnace wall temperature at 1050°C to obtain coke. The obtained coke was cooled under a nitrogen atmosphere, and then its particle size was adjusted to 19-21 mm, and it was subjected to a reactivity test (CRI) and a post-reaction strength test (CSR).

[0065] Table 1 shows the metal oxide content in the ash of the molded coal (see "Na2O," "K2O," "CaO," "MgO," and "Fe2O3" in Table 1), the ash content in the molded coal (see "Ash" in Table 1), the reactivity of the coke obtained by carbonizing a blend of molded coal and powdered coal (see "CRI" in Table 1), and the strength after reaction (see "CSR" in Table 1). The ash content (Ash) was calculated using the method of JIS M8812:2006. CAsh is a value calculated by equation (6) using coefficients a to e that were determined in advance, as described in the embodiment. ΔCAsh is the CAsh of the molded coal. bq and CASh in pulverized coal p Shows the difference between.

[0066] [Table 1]

[0067] The "standard" condition is an example in which the composition of the coal blend in the briquettes and the powdered coal is the same. In other words, the CAsh in the "standard" is the CAsh in the briquettes. bq and CASh in pulverized coal p In other words, the value of ΔCAsh is "0.0" as shown in Table 1.

[0068] In Examples 1 to 3, the blending of coal in the powdered coal was the same as in the "standard" case, but the blending of coal in the briquettes was changed to produce briquettes with a high metal oxide content. Therefore, in Examples 1 to 3, as shown by the value of ΔCAsh, the CAsh of the briquettes bq The value of CAsh (= CAsh) is based on the "standard" formulation. bq =CAsh p ) is a value larger than the value of

[0069] Here, the relationship between the ΔCAsh value, reactivity (CRI), and post-reaction strength (CSR) in Table 1 will be explained using Fig. 3. Fig. 3 is a diagram showing the relationship between the ΔCAsh value and reactivity (CRI) or post-reaction strength (CSR).

[0070] In Figure 3, the plots where the ΔCAsh value is 0 ("□" in the figure) show the results of the "standard" in Table 1. The "standard" is the CAsh of the molded coal. bq and CASh in pulverized coal p As shown in the results of Examples 1 to 3 (marked with "●" in the figure), the CAsh in the molded coal bq It was confirmed that even under conditions where ΔCAsh is large, i.e., conditions where there is a large amount of metal oxide in the molded coal that affects the reaction degradation, the strength and reactivity after the reaction hardly change regardless of the magnitude of ΔCAsh. In other words, it was confirmed that the method of the present invention allows the use of coal with a large amount of metal oxide without causing the reaction degradation of the coke.

[0071] The plots marked with "△" in Fig. 3 show the results when the coals (including binders, etc.) used in the molded coal of Example 2 were mixed with powdered coal without molding, and 20% (by mass) of the mixture was molded and carbonized. The data marked with "△" have the same CAsh as the molded coal and the powdered coal, so the ΔCAsh value is 0. However, since the blend of coal charged into the coke oven is the same as in Example 2, the data are plotted in the same position on the horizontal axis (ΔCAsh value) as in Example 2, taking into consideration the visibility of the data in Fig. 3.

[0072] For the data indicated by "△", it was confirmed that the reactivity (CRI) increased and the post-reaction strength (CSR) decreased as a result of the metal oxides contained in the molded coal of Example 2 also being contained in the powdered coal. Furthermore, by comparing Examples 1 to 3 ("●" in the figure) with the comparative example ("△" in the figure) in Figure 3, it was confirmed that the method of the present invention can suppress the reaction deterioration of coke.

Claims

[Claim 1] A coke manufacturing method comprising carbonizing a coal blend containing molded coal and powdered coal to manufacture coke, The ash content of the briquettes and the metal content or the metal oxide content of the ash of the briquettes are determined; Calculating the ash content of the powdered coal and the metal content or metal oxide content of the ash of the powdered coal; CAsh calculated from the ash content and the metal content or the metal oxide content in the obtained molded coal ｂｑ (mass%), and CAsh calculated from the ash content and the metal content or the metal oxide content in the obtained powdered coal. ｐ a carbonization process for carbonizing a coal blend in which the metal content or the metal oxide content in the molded coal and the powdered coal is adjusted so that the metal content or the metal oxide content (mass%) of the molded coal and the powdered coal satisfies the following formula (1): CAsh ｂｑ (mass%) > CAsh ｐ (mass%)...(1) Here, CAS ｂｑ (mass%) is calculated by the following formula (6), and ｐ (mass%) is calculated by the following formula (4): CAsh ｂｑ (mass%) = Ash ｂｑ (mass%) × (a × Na) ２ O ｂｑ (mass%) + b × K ２ O ｂｑ (mass%) + c × CaO ｂｑ (mass%) + d × MgO ｂｑ (mass%) + e × Fe ２ O ３ｂｑ (mass%) / 100 ・・・(6) CAsh ｐ (mass%) = Ash ｐ (mass%) × (a × Na) ２ O ｐ (mass%) + b × K ２ O ｐ (mass%) + c × CaO ｐ (mass%) + d × MgO ｐ (mass%) + e × Fe ２ O ３ｐ (mass%) / 100 ・・・(4) Ash ｂｑ (mass%) is the ash content in the molded coal, Ash ｐ (mass%) is the ash content in the powdered coal, Na ２ O ｂｑ (mass%) is the Na content in the ash of the molded coal ２ O content, Na ２ O ｐ (mass%) is the Na content of the ash of the powdered coal ２ O content rate, K ２ O ｂｑ (mass%) is the K in the ash content of the molded coal ２ O content, K ２ O ｐ (mass%) is the K in the ash content of the powdered coal ２ O content rate, CaO ｂｑ (mass%) is the CaO content in the ash of the molded coal, CaO ｐ (mass%) is the CaO content in the ash of the powdered coal, MgO ｂｑ (mass%) is the MgO content in the ash of the molded coal, MgO ｐ (mass%) is the MgO content in the ash of the powdered coal, Fe ２ O ３ｂｑ (mass%) is the Fe content in the ash of the molded coal ２ O ３ Content rate, Fe ２ O ３ｐ (mass%) is the Fe content in the ash of the powdered coal ２ O ３ The content rate is shown. a, b, c, d, and e are the values ​​of the ash content of the powder coal, the Na content of the ash, and the strength or reactivity of the coke after carbonization of the powder coal as the objective variable. ２ O.K. ２ O, CaO, MgO 、 Fe ２ O ３ The coefficient is determined by multiple regression analysis using the content rate of

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