Method for producing coal cake, method for producing metallurgical coke, and strength enhancing material for coal cake

Abstract

Provided is a method for producing a coal cake that can improve the strength of the coal cake without using an adhesive binder. The method for producing a coal cake of the present disclosure is a method for producing a coal cake in a stamp charge coke oven, the method comprising: blending and mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more with a powdered raw material for coal cake, and stamping a resulting fiber-mixed raw material to obtain a coal cake.

Description

TECHNICAL FIELD

[0001] This disclosure relates to a method for producing a coal cake, a method for producing metallurgical coke, and a method for producing a strength-enhancing material for coal cake.BACKGROUND

[0002] Currently, in the production of pig iron using a blast furnace, coke produced by dry distillation of coal in a coke oven is used as a reducing agent for iron ore and to ensure gas permeability in the blast furnace. It is known that high-strength coke is preferable for efficient blast furnace operation. This is because if the coke disintegrates into fine particles inside the blast furnace, the resulting fines deteriorate the gas permeability of the blast furnace, which hinders efficient blast furnace operation.

[0003] It is known that increasing the bulk density of coal charged into the coke oven is effective in producing high-strength coke, and stamp charge coke ovens are used for this purpose. In the commonly used coke ovens in Japan (hereinafter referred to as "top charge coke ovens"), the coal serving as the raw material for coke is charged by gravity from the top of a coking chamber of the coke oven, and the bulk density of the coal charged by gravity is 700 kg-dry / m 3< to 800 kg-dry / m 3< .

[0004] On the other hand, in a stamp charge coke oven, coal is compacted by a stamping device located on the side of the coking chamber of the coke oven before being charged into the oven. The coal is formed into a coal cake with a bulk density of 1000 kg-dry / m 3< or more, and then mechanically charged into the coking chamber of the coke oven from the side. As described above, by using a stamp charge coke oven, it is possible to increase the density of the coke raw material prior to dry distillation, thereby enabling the production of high-strength coke compared to that produced using a top charge coke oven.

[0005] As described above, the stamp charge coke oven offers an advantage over the top charge coke oven in terms of coke strength. However, if the strength of the coal cake formed by stamping is low, the coal cake may collapse during the process of being charged into the coking chamber, leading to operational trouble. Therefore, a technique for producing high-strength coal cakes is required for stable operation of stamp charge coke ovens.

[0006] It is also known that the strength of a coal cake is greatly influenced by the moisture content of the coal. In stamp charge coke ovens, it is common to adjust the moisture content of the coal to 10 mass% to 12 mass%. However, when the moisture content of the coal cake is high, the dry distillation time increases accordingly, resulting in reduced productivity. Therefore, to improve the productivity of stamp charge coke ovens, it is necessary to develop a technique for producing coal cakes with sufficient strength for operation while keeping a low moisture content in the coal.

[0007] The use of adhesive binders has been studied for the above-mentioned purpose. For example, JP H07-109467 A (PTL 1) reports a method in which adhesive coal is heated to 300 °C to 500 °C, and the coal in a softened and molten state is used as a binder for coal cakes. Additionally, S. H. Krishnan, et al., "Application of Binder in Stamp Charge Coke Making", ISIJ International, 44(2004), 1150. (NPL 1) reports that by adding pitch with a softening point of 80 °C as a binder to raw materials, coal cakes can be strengthened, allowing for the production of coal cakes with sufficient strength even under conditions where the coal moisture content is lower than usual.CITATION LISTPatent Literature

[0008] PTL 1: JP H07-109467 ANon-patent Literature

[0009] NPL 1: S. H. Krishnan, et al., "Application of Binder in Stamp Charge Coke Making", ISIJ International, 44(2004), 1150.SUMMARY(Technical Problem)

[0010] In the methods using adhesive binders as described in PTL 1 and NPL 1, the adhesive raw material adheres to belt conveyors and the stamping device during the process of transporting the coke raw material containing the adhesive binder, as well as during the compaction process by the stamping device. As a result, frequent cleaning of the equipment is required, leading to a reduction in productivity.

[0011] It could thus be helpful to provide a method for producing a coal cake that can improve the strength of the coal cake without using an adhesive binder.(Solution to Problem)

[0012] We conducted extensive research to solve the above-mentioned problems and obtained experimental results indicating that the strength of the coal cake can be improved by mixing synthetic fibers such as polyethylene with the raw material for coal cake. We also discovered that fibers can be used as a binder for stamp charge coke ovens, and that the length of the fibers has a significant effect on the strength of the coal cake. Furthermore, in response to the recent societal demand for carbon neutrality, we discovered that similar effects can be obtained by using plant-based materials in fibrous form, thereby completing the present disclosure.

[0013] Specifically, primary features of the present disclosure are as follows. [1] A method for producing a coal cake in a stamp charge coke oven, the method comprising: blending and mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more with a powdered raw material for coal cake, and stamping a resulting fiber-mixed raw material to obtain a coal cake. [2] The method for producing a coal cake according to [1], wherein a blending ratio of the fibers is 2.0 mass% or less with respect to 100 mass% of the raw material for coal cake. [3] A method for producing metallurgical coke, comprising producing a coal cake with the method according to [1] or [2], and subjecting the coal cake to dry distillation in a coke oven to obtain coke. [4] A strength-enhancing material for coal cake used in a stamp charge coke oven, comprising fibers having a length of 1.0 mm or more and 200 mm or less. (Advantageous Effect)

[0014] According to the present disclosure, it is possible to provide a method for producing a coal cake that can improve the strength of the coal cake without using an adhesive binder. Moreover, according to the present disclosure, it is also possible to produce a coal cake with sufficient strength for operation while keeping a low moisture content in the coal.DETAILED DESCRIPTION

[0015] The following describes an embodiment of the present disclosure. The method for producing a coal cake according to the present disclosure is a method for producing a coal cake in a stamp charge coke oven, the method comprising: blending and mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more with a powdered raw material for coal cake, and stamping the resulting fiber-mixed raw material to obtain a coal cake.

[0016] First, fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more are blended and mixed with a raw material for coal cake to obtain a fiber-mixed raw material.[Raw material for coal cake]

[0017] A powdered blended coal that is mainly composed of raw coal and is generally used for coke production can be used as the raw material for coal cake. As long as the quality of the coke obtained by dry distillation of the coal cake is not a concern, materials other than raw coal may also be used, such as non-micro-bonding coal, biomass, carbides obtained by heating biomass, or other carbon-based raw materials.

[0018] The raw material may be crushed using, for example, a hammer crusher, as is conventionally done in the operation of stamp charge coke ovens. The crushing should be such that the particle size is -3 mm 70 mass% to 100 mass% (i.e., particles of 3 mm or less account for 70 mass% to 100 mass%), after which it may be used as the raw material for coal cake.

[0019] Moisture adjustment of the raw material for coal cake can be performed before and after the crushing treatment using, for example, coal moisture adjustment equipment for drying and water spraying from nozzles. From the perspective of increasing the strength of the coal cake, the target moisture content of the raw material for coal cake is preferably 10 mass% to 12 mass%. However, from the perspective of improving productivity, the moisture content may be reduced within a range that does not weaken the strength of the coal cake.[Fibers]

[0020] Synthetic fibers such as nylon and polyester, or natural fibers such as silk or cotton cut to arbitrary lengths may be used as the fibers. In addition, plant-based materials in fibrous form may also be used. A specific example of the plant-based materials in fibrous form is a fiber obtained by mechanically loosening the empty fruit bunches (EFB) of oil palms (referred to as "EFB fiber").

[0021] In recent years, in response to societal demands for reducing CO 2 emissions, the use of palm oil and oil palm shells derived from oil palms as fuel for biomass power generation has been increasing as a substitute for conventional fossil fuels. On the other hand, the empty fruit bunches (EFB), which are residues after harvesting the fruit from the oil palms, are high in moisture and ash content and are prone to decay, and thus most of them are currently discarded. These EFBs have a fibrous structure, and by mechanically loosening them, fibers with a diameter of approximately 0.5 mm to 1.0 mm and a length of approximately 50 mm to 100 mm can be obtained.

[0022] In this way, by focusing on the shape of plant materials that are currently discarded and utilizing them as a binder in stamp charge coke ovens, effective resource utilization can be achieved. In addition to the above-mentioned substances, any fiber composed mainly of carbon, oxygen, and hydrogen may similarly be used as a binder in stamp charge coke ovens.

[0023] In the present disclosure, fibers having a certain minimum length are mixed and dispersed into the raw material for coal cake, thereby forming a network of interlaced fibers and producing a fiber-mixed raw material. As a result, coal cakes with high strength can be produced.

[0024] The longer the fibers are, the more contact they make with each other, forming a fiber network that extends throughout the coal cake. To improve the strength of the coal cake, the fiber length needs to be 1.0 mm or more. The fibers are preferably longer in terms of improving the strength of the coal cake, and the length of the fibers to be mixed with the coal cake raw material is preferably 3.0 mm or more, and more preferably 5.0 mm or more. On the other hand, increasing the fiber length beyond 200 mm saturates the strength of the coal cake and also results in poor mixability with the powdered raw material for coal cake. Therefore, the length of the fibers to be mixed with the raw material for coal cake is set to 200 mm or less, preferably 180 mm or less, and more preferably 160 mm or less.

[0025] The length of the fibers does not need to be uniform, and variation in length is acceptable. It is sufficient if a prescribed amount of fiber with a length of 1.0 mm or more and 200 mm or less are mixed. Fibers with a length of less than 1.0 mm do not contribute to the improvement of the strength of the coal cake, but since they also do not weaken the strength, the inclusion of such fine fibers is not problematic. Fibers with a length of 200 mm or more, while not significantly reducing strength when present in small amounts, may decrease the strength if included in large quantities. Therefore, it is preferable not to intentionally include fibers with a length of 200 mm or more. Additionally, fibers that are thick and short, i.e., those with a shape closer to spherical, are less likely to form the above-mentioned interlaced network when mixed into the coal cake. As indicated in the examples described later, using thick and short fibers does not improve coal cake strength, but since they also do not weaken the strength, the inclusion of thick and short fibers is not problematic. What is essential is the inclusion of elongated fibers, and a higher length-to-diameter ratio is preferable. In the present disclosure, the length-to-diameter ratio of the fibers is set to 10 or more, preferably 15 or more, and more preferably 30 or more.

[0026] When using cut synthetic or natural fibers, there is an advantage in that the fiber length can be arbitrarily set over a wide range in consideration of the target coal cake strength specified at each plant and the ease of mixing the fibers with the raw material for coal cake. On the other hand, when using plant-based materials in fibrous form, it is difficult to arbitrarily set the fiber length, but these materials offer advantages in terms of reducing CO 2 emissions by replacing fossil fuel-based binders with biomass-based raw materials. The type and length of the fibers may be determined arbitrarily according to the operational targets (such as coal cake strength and CO 2 emission reduction) and the capacity of mixing equipment of each plant.

[0027] In the present disclosure, a coal cake with high strength can be produced by stamping and compacting a fiber-mixed raw material, which is obtained by mixing and blending the fibers with the above-described powdered raw material for coal cake.

[0028] As indicated in the examples described later, when the fiber blending ratio relative to the raw material for coal cake increases, the coal cake strength improves. Therefore, from the perspective of coal cake strength improvement, there is no specific upper limit to the blending ratio. However, in the present disclosure, even a small amount of fiber mixed into the raw material for coal cake demonstrates a remarkable strength-improving effect. From the perspective of preventing coal cake collapse and ensuring stable operation, excessively increasing the strength of the coal cake offers limited benefit. Therefore, from an economic perspective, it is preferable that the blending ratio of the fibers be 2.0 mass% or less with respect to 100 mass% of the raw material for coal cake. Note that the blending ratio of the fibers being 2.0 mass% or less means that the dry mass of the fibers accounts for 2.0 mass% or less on an external basis, with respective to the total dry mass (100 mass%) of the raw materials used for producing the coal cake (such as coal, carbonized coal, and other carbon materials, excluding the fiber). The blending ratio of the fibers is more preferably 1.5 mass% or less, and still more preferably 1.0 mass% or less.

[0029] On the other hand, even when the blending ratio of the fibers is low, the addition of fibers still produces a corresponding improvement in coal cake strength, and therefore the lower limit of the blending ratio is not particularly restricted. However, from the perspective of producing higher-strength coal cakes and preventing their collapse, the blending ratio of the fibers is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, and still more preferably 0.05 mass% or more.

[0030] It should be noted that the raw material for coal cake and the plant-based fibers generally contain a certain amount of moisture. Therefore, the blending ratio of the fibers should be calculated using the dry mass (excluding moisture), based on prior measurement of the moisture content of both the raw material for coal cake and the fibers. The moisture content of the fibers is determined based on the air-drying loss method specified in JIS M 8812, calculated from the weight loss of a sample after drying at 107 °C for one hour. Although this method is defined for determining the moisture content of coal, it may also be used to measure the moisture content of coal cake raw materials or fibers that include non-coal components.

[0031] The method for blending and mixing the fibers with the raw material for coal cake is not particularly limited, and a mixer commonly used in coke plants for mixing coal may be used. To improve productivity by blending and mixing the fibers into a large amount of coal cake raw material in a shorter time, a method using a mixer equipped with chopper blades, such as the PAM Apex Mixer (manufactured by Taiheiyo Kiko Co., Ltd.), can be exemplified.

[0032] When producing coal cakes with the fiber-mixed raw material prepared as described above, it is sufficient to use a stamping device that compacts the fiber-mixed raw material by means of drop-weight impact. In this case, by mixing fibers with a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more, it is possible to produce a coal cake with higher strength than that produced without fibers. As a result, the collapse of the coal cake can be prevented, and stable operation of the coke oven can be achieved. Furthermore, even under operating conditions where the coal moisture content is low and coal cake collapse would normally occur frequently, the strength of the coal cake can be maintained within an operationally acceptable range when the above fibers are mixed. The effects of fiber mixing on coal cake strength will be described in more detail in the following examples.(Method for producing metallurgical coke)

[0033] Next, a method for producing metallurgical coke according to the present disclosure will be described. In the method for producing metallurgical coke according to the present disclosure, a coal cake produced with the above-described method for producing a coal cake according to the present disclosure is subjected to dry distillation in a coke oven.

[0034] The coal cake produced with the above-described method for producing a coal cake according to the present disclosure is mechanically charged into a coking chamber of the coke oven from the side. At this time, the coal cake is subjected to impact from its own weight and from the vibration of the charging machine. If the coal cake has insufficient strength, operational problems such as collapse of the coal cake during charging may occur. In the method for producing a coal cake according to the present disclosure, fibers are used as a binder, which improves the strength of the coal cake and helps suppress its collapse.

[0035] The conditions for dry distillation of the coal cake are not particularly limited. It is sufficient to perform the dry distillation at a temperature of approximately 900 °C or higher using a common stamp charge coke oven.(Strength-enhancing material for coal cake)

[0036] Next, a strength-enhancing material for coal cake according to the present disclosure will be described. The strength-enhancing material for coal cake according to the present disclosure is used in a stamp charge coke oven, and it is composed of fibers having a length of 1.0 mm or more and 200 mm or less.

[0037] The above fibers may be the same as the fibers used in the above-described method for producing a coal cake according to the present disclosure. The requirements for the fibers may also be the same as those described for the fibers used in the method for producing a coal cake.

[0038] As described above, by blending and mixing fibers having a length of 1.0 mm or more and 200 mm or less as a binder with the raw material for coal cake and stamping the resulting fiber-mixed raw material, a high-strength coal cake can be produced. As a result, when the produced coal cake is subjected to dry distillation in a coke oven to produce coke, the collapse of the coal cake can be suppressed, allowing for stable operation of the coke oven.EXAMPLES

[0039] The following describes examples of the present disclosure. However, the present disclosure is not limited to the following examples and may be modified as appropriate without departing from the gist of the present disclosure.(Example 1)

[0040] In Example 1, a raw material for coal cake was blended and mixed with polyethylene fibers and polypropylene fibers having different lengths and diameters, and coal cakes were produced with the method for producing a coal cake according to the present disclosure. The strength of the resulting coal cakes was evaluated.

[0041] As the raw material for coal cake, a blended coal was prepared by blending raw coals such that the weighted average coalification degree (Ro) was 0.94, and then the blended coal was crushed so that the particle size was -3 mm 90 mass%. The polyethylene or polypropylene fibers were cut to the lengths listed in Table 1 and blended and mixed at the blending ratios listed in Table 1 with the raw material for coal cake. The moisture content of the mixture was measured, and a calculated amount of water was added so that the final moisture content would be 10 mass%, which is a standard condition for stamp charge coke ovens.[Table 1]

[0042] Table 1Fiber raw materialFiber diameter (mm)Fiber length (mm)Length / DiameterFiber blending ratio (mass%)Moisture content of coal cake raw material (mass%)Uniaxial compressive strength of coal cake (kN / m 2< )Strength ratio relative to referenceRemarks----0.0101341.00ReferencePolyethylene0.15500.5101541.15ExamplePolyethylene0.1101000.5102281.70ExamplePolyethylene0.1202000.5102832.11ExamplePolyethylene0.1404000.1101741.30ExamplePolyethylene0.1404000.2102661.99ExamplePolyethylene0.1404000.5104513.37ExamplePolyethylene0.1404001.0106114.56ExamplePolyethylene0.1404001.5106494.84ExamplePolyethylene0.1808000.5105213.89ExamplePolyethylene0.116016000.5105353.99ExamplePolyethylene0.120020000.5105103.81ExamplePolypropylene1.254.20.5101180.88Comparative ExamplePolypropylene1.2108.30.5101270.95Comparative ExamplePolypropylene1.22016.70.5101441.07ExamplePolypropylene1.24033.30.5101491.11ExamplePolypropylene1.28066.70.5101921.43Example

[0043] Using the fiber-mixed raw material whose moisture content had been adjusted as described above, coal cakes were produced by the following procedure. First, approximately 200 g of the fiber-mixed raw material was loaded into a metal mold with an inner diameter of 10 cm and a height of 20 cm. A 9 kg rammer was dropped onto the surface of the material from a height of 30 cm, ten times, to compact the loaded fiber-mixed raw material by impact. This process, from loading the coal into the mold to dropping the rammer, was repeated ten times, resulting in a coal cake with a diameter of 10 cm, a height of 20 cm, and a weight of approximately 2 kg. After that, the mold was gently removed from the coal cake, and the strength of the coal cake was measured. The strength of the coal cake was evaluated based on the uniaxial compressive strength as specified in JIS A 1216. The results are listed in Table 1.

[0044] Table 1 lists the strength of coal cakes in cases of blending and mixing synthetic fibers of various lengths and diameters with the raw material for coal cake. The coal cake strength (uniaxial compressive strength) varies significantly depending on the type and particle size of the raw material for coal cake used. Therefore, in evaluating the effect of additives on coal cake strength, it is preferable to use the uniaxial compressive strength of a coal cake produced under standard conditions for stamp charge coke ovens as a reference, where the moisture content is 10 mass% and no additives are added, and to evaluate the effect based on a strength ratio relative to this reference for each coal cake raw material.

[0045] If the strength ratio is less than 1.0, it indicates that the coal cake strength is lower than that under standard operating conditions, and it is likely to cause problems such as the collapse of the coal cake. On the other hand, if the strength ratio exceeds 1.0, it indicates that the coal cake strength is higher than that under standard operating conditions, and it is a favorable condition for stable operation with less likelihood of coal cake collapse. From this perspective, in Comparative Examples where polypropylene fibers with a diameter of 1.2 mm were cut to lengths of 5 mm or 10 mm and mixed in, the strength ratio relative to the reference was less than 1.0, indicating that mixing the fibers reduced the strength of the coal cake and increased the likelihood of coal cake collapse. The reason is considered as follows. Under the conditions of Comparative Examples, the shape of the additives was close to spherical, preventing the formation of an interlaced fiber network and thereby failing to produce any strength enhancing effect on the coal cake.

[0046] On the other hand, in Examples, the mixing of the fibers led to an increase in coal cake strength and a reduction in the likelihood of coal cake collapse, representing favorable conditions for stable operation. The results of this example clearly demonstrate that mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more with the raw material for coal cake can improve the strength of the coal cake.(Example 2)

[0047] In Example 2, the effect of fiber mixing on coal cake strength was investigated under a condition where the moisture content was as low as 7 mass%, which is lower than standard stamp charge operating conditions where the moisture content of the coal cake raw material is 10 mass%. For this purpose, coal cakes were produced with the method for producing a coal cake according to the present disclosure, and their strength was evaluated.

[0048] As the raw material for coal cake, a blended coal was prepared by blending raw coals such that the weighted average coalification degree (Ro) was 0.94, and then the blended coal was crushed so that the particle size was -3 mm 90 mass%. The polyethylene or polypropylene fibers were cut to the lengths listed in Table 2 and blended and mixed at the blending ratios listed in Table 2 with the raw material for coal cake. The moisture content of the mixture was measured, and a calculated amount of water was added so that the final moisture content would be 10 mass%, which is a standard condition for stamp charge coke ovens, or 7 mass%, which is a lower-than-usual moisture condition.

[0049] Using the fiber-mixed and moisture-adjusted coal cake raw material prepared as above, coal cakes were produced with the same method as in Example 1, and their strength was measured. The results are listed in Table 2.[Table 2]

[0050] Table 2Fiber raw materialFiber diameter (mm)Fiber length (mm)Length / DiameterFiber blending ratio (mass%)Moisture content of coal cake raw material (mass%)Uniaxial compressive strength of coal cake (kN / m 2< )Strength ratio relative to referenceRemarks----0.0101341.00Reference----0.07610.46Reference ExamplePolypropylene1.2108.30.57550.41Comparative ExamplePolypropylene1.2108.31.07430.32Comparative ExamplePolyethylene0.1202000.572321.73ExamplePolyethylene0.1404000.271841.37ExamplePolyethylene0.1404000.572782.07ExamplePolyethylene0.1808000.574363.25Example

[0051] Table 2 indicates the effect of fiber mixing on coal cake strength in a case where the coal moisture is lower than that of standard conditions for stamp charge coke ovens. As indicated as a reference example in Table 2, when the moisture content of the coal cake raw material is reduced from 10 mass% to 7 mass%, the strength ratio of the coal cake relative to the reference decreases to 0.46. Under such conditions, coal cake collapse occurs frequently, making stable coke production difficult. Further, in Comparative Examples where polypropylene fibers with a diameter of 1.2 mm and a length of 10 mm were mixed in, the strength of the coal cake was lower than that without fiber mixing. On the other hand, in Examples, it was found that mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more resulted in a strength ratio higher than the reference, even under conditions where the moisture content of the coal cake raw material was 7 mass%. In other words, by mixing fibers, it is possible to reduce the moisture content of the coal cake while maintaining the strength of the coal cake, thereby improving the productivity of coke.(Example 3)

[0052] In Example 3, fibers obtained from oil palm empty fruit bunches (EFB fibers) were mixed with the raw material for coal cake, and coal cakes were produced with the method for producing a coal cake according to the present disclosure. The strength of the resulting coal cakes was evaluated.

[0053] As the raw material for coal cake, a blended coal was prepared by blending raw coals such that the weighted average coalification degree (Ro) was 0.93, and then the blended coal was crushed so that the particle size was -3 mm 90 mass%. The EFB fibers were blended and mixed with the raw material for coal cake at the blending ratios listed in Table 3. The diameter of the EFB fibers used was uniformly 0.8 mm, but the lengths varied between 50 mm and 100 mm. Therefore, a range was allowed for the fiber length and the length-to-diameter ratio. The moisture content of the mixture was measured, and a calculated amount of water was added so that the final moisture content would be 10 mass%, which is a standard condition for stamp charge coke ovens. Using the EFB fiber-mixed and moisture-adjusted coal cake raw material prepared as above, coal cakes were produced with the same method as in Example 1, and the strength of the resulting coal cakes was measured. The results are listed in Table 3.[Table 3]

[0054] Table 3Fiber raw materialFiber diameter (mm)Fiber length (mm)Length / DiameterFiber blending ratio (mass%)Moisture content of coal cake raw material (mass%)Uniaxial compressive strength of coal cake (kN / m 2< )Strength ratio relative to referenceRemarks----0.0101391.04ReferenceEmpty fruit bunch (EFB) of oil palm0.850-10062.5-1250.2101561.16ExampleEmpty fruit bunch (EFB) of oil palm0.850-10062.5-1250.5102571.92ExampleEmpty fruit bunch (EFB) of oil palm0.850-10062.5-1251.0103422.55Example

[0055] As indicated in Table 3, the strength of the coal cake was improved by mixing plant-based fibrous materials, such as EFB fibers. This demonstrates that such plant-based fibrous materials can be used as clean binders in stamp charge coke ovens, as an alternative to fossil fuel-derived binders.INDUSTRIAL APPLICABILITY

[0056] According to the present disclosure, it is possible to improve the strength of coal cakes without using an adhesive binder.

Claims

1. A method for producing a coal cake in a stamp charge coke oven, the method comprising: blending and mixing fibers having a length of 1.0 mm or more and 200 mm or less and a length-to-diameter ratio of 10 or more with a powdered raw material for coal cake, and stamping a resulting fiber-mixed raw material to obtain a coal cake.

2. The method for producing a coal cake according to claim 1, wherein a blending ratio of the fibers is 2.0 mass% or less with respect to 100 mass% of the raw material for coal cake.

3. A method for producing metallurgical coke, comprising producing a coal cake with the method according to claim 1 or 2, and subjecting the coal cake to dry distillation in a coke oven to obtain coke.

4. A strength-enhancing material for coal cake used in a stamp charge coke oven, comprising fibers having a length of 1.0 mm or more and 200 mm or less.

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