Biomass charcoal for stamp-charge type coke ovens, method for producing biomass charcoal for stamp-charge type coke ovens, and method for producing coke.

Abstract

The present invention provides biomass charcoal for stamp-charge type coke ovens, a method for producing biomass charcoal for stamp-charge type coke ovens, and a method for producing coke, which can suppress a decrease in the strength of the coal cake even when a portion of the coal used as raw material for the coal cake carbonized in a stamp-charge type coke oven is replaced with biomass charcoal. A method for producing biomass charcoal for a stamp-charge type coke oven, comprising: a carbonization step (step S1) in which biomass raw materials are carbonized such that the atomic ratio H / C, which is the ratio of hydrogen atoms to the number of carbon atoms, is greater than 0.25 and less than 0.45; and a grinding step (step S2) in which the biomass charcoal for a stamp-charge type coke oven produced by carbonizing the biomass raw materials in the carbonization step is ground so that the proportion of particles with a particle size of 3 mm or less is 90% by mass or more, and the proportion of particles with a particle size of 1 mm or less is 65% by mass or more.

Description

Technical Field

[0001] The present invention relates to biomass charcoal for a stamp-charged coke oven, a method for producing the biomass charcoal for a stamp-charged coke oven, and a method for producing coke.

Background Art

[0002] In the production of pig iron using a blast furnace, coke produced by carbonizing coal in a coke oven is used for the purpose of reducing iron ore, serving as a heat source, and ensuring air permeability in the blast furnace.

[0003] In recent years, the need to reduce CO2 emissions has been increasing. In order to reduce CO2 emissions in a blast furnace, studies are underway to replace part of the coal, which is a raw material for coke used in the blast furnace, with a carbon-neutral raw material such as biomass.

[0004] The coal used for coke production adheres to each other and agglomerates by softening and melting upon heating. However, biomass charcoal does not soften and melt upon heating. When such biomass charcoal is used for coke production, there is concern about a decrease in coke strength due to poor adhesion between the coal-derived part and the biomass charcoal-derived part of the produced coke. Therefore, in coke production, techniques for suppressing a decrease in coke strength caused by the use of biomass charcoal have been conventionally studied. Patent Document 1 discloses a method for producing coke in which a woody biomass having appropriate volatile content and particle size is blended with blended coal, which is a raw material for coke. In Patent Document 1, it is said that by doing so, defects due to peeling between the coal-derived part and the biomass charcoal-derived part of the produced coke can be suppressed, and a decrease in coke strength can be suppressed. In Patent Document 1, the blended coal is not rammed before carbonization. Therefore, the coke oven used for coke production in Patent Document 1 is a top-charged coke oven, which will be described later.

[0005] On the other hand, it is known that improving the bulk density of the coal charged into the coke oven is effective in producing high-strength coke. Stamp-charge coke ovens are known as coke ovens that produce coke using coal with improved bulk density. In a stamp-charge coke oven, coal is compacted by a stamping device and formed into a block shape that is slightly smaller in size than the carbonization chamber. Hereafter, the compacted coal mass will be called a coal cake. Subsequently, the coal cake is charged into the carbonization chamber from the side and carbonized to produce coke.

[0006] A typical coke oven is a top-charge type coke oven, where coal is charged into the carbonization chamber by gravity. In a top-charge type coke oven, the bulk density of the coal in the carbonization chamber is 700-800 kg-dry / m³. 3 That is the case.

[0007] In contrast, in a stamp-charge coke oven, as mentioned above, coal cake is produced by a stamping device. Therefore, the bulk density of the coal cake is higher than that of the coal in the carbonization chamber in a top-charge coke oven, at 1000 kg-dry / m³. 3 This is the extent of the problem. In this way, the bulk density of the coke raw materials can be increased before carbonization in a stamp-charge type coke oven. Therefore, even if biomass coal is used in coke production, defects caused by the separation of the coal-derived portion from the biomass coal-derived portion of the coke after production can be suppressed. Consequently, the concern about a decrease in coke strength due to the use of biomass coal in a stamp-charge type coke oven is smaller than in the case of a top-charge type coke oven. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2024 / 181565 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In stamp-charge type coke ovens, the strength of the coal cake produced by stamping is crucial. This is because if the coal cake is not strong enough, operational problems may occur, such as the coal cake collapsing during charging into the carbonization chamber. Therefore, various studies have been conducted on the relationship between the properties of coal and the strength of the coal cake. However, sufficient research has not been done on the properties and production methods of biomass coal that can suppress the decrease in coal cake strength, and there is still room for improvement in this regard.

[0010] The technology disclosed in Patent Document 1 investigates the properties of woody biomass blended with coal when producing high-strength coke in a top-charge coke oven. Therefore, Patent Document 1 does not disclose anything about the properties of biomass charcoal that can suppress the reduction in strength of coal cake, nor does it disclose any method for producing biomass charcoal.

[0011] The present invention has been made to solve the above-mentioned problems, and aims to provide biomass charcoal for stamp-charge type coke ovens, a method for producing biomass charcoal for stamp-charge type coke ovens, and a method for producing coke, which can suppress a decrease in the strength of the coal cake even when a portion of the coal, which is the raw material for the coal cake carbonized in a stamp-charge type coke oven, is replaced with biomass charcoal. [Means for solving the problem]

[0012] The means to solve the above-mentioned problems are as follows: [1] A method for producing biomass charcoal for a stamp-charge coke oven, which is mixed together with coal in a coal cake that is charged into the stamp-charge coke oven and carbonized, comprising: a carbonization step of carbonizing a biomass raw material such that the atomic ratio H / C, which is the ratio of hydrogen atoms to the number of carbon atoms, is greater than 0.25 and less than 0.45; and a grinding step of grinding the biomass charcoal for a stamp-charge coke oven produced by carbonizing the biomass raw material in the carbonization step such that the proportion of particles with a particle size of 3 mm or less is 90% by mass or more, and the proportion of particles with a particle size of 1 mm or less is 65% by mass or more. [2] The method for producing biomass charcoal for a stamp-charge type coke oven according to [1], wherein the biomass raw material is carbonized at a temperature of 400 to 600°C in the carbonization step. [3] The biomass raw material to be carbonized in the carbonization step is seed husks, a method for producing biomass charcoal for a stamp charge type coke oven as described in [1] or [2]. [4] The method for producing biomass charcoal for a stamp charge coke oven according to [3], wherein the seed husk is at least one of palm husks, walnut husks, coconut husks, pistachio husks, and cashew nut husks. A method for producing coke, comprising: a stamping step of stamping a blended coal containing biomass coal for a stamp-charge type coke oven and coal, prepared by a method for producing biomass coal for a stamp-charge type coke oven described in any of [5] [1] to [4], to produce a coal cake; and a carbonization step of charging the coal cake produced in the stamping step into a stamp-charge type coke oven and carbonizing it to produce coke. [6] Biomass charcoal for stamp-charge coke ovens, which is mixed together with coal in coal cake that is carbonized in a stamp-charge coke oven, wherein the atomic ratio H / C, which is the ratio of hydrogen atoms to the number of carbon atoms, is greater than 0.25 and less than 0.45, the proportion of particles with a particle size of 3 mm or less is 90% by mass or more, and the proportion of particles with a particle size of 1 mm or less is 65% by mass or more. [Effects of the Invention]

[0013] According to the present invention, even if a portion of the coal used as a raw material for coal cake is replaced with biomass coal when manufacturing stamp-charge coke, a decrease in the strength of the coal cake can be suppressed. Furthermore, since a portion of the coal used as a raw material for coal cake is replaced with biomass coal when manufacturing coke, it can contribute to reducing CO2 emissions. [Brief explanation of the drawing]

[0014] [Figure 1] This is a flowchart illustrating the method for producing biomass charcoal for a stamp-charge type coke oven and the method for producing coke according to this embodiment. [Figure 2] This figure shows the types of biomass raw materials and the relationship between the atomic ratio and the strength ratio of coal cake. [Figure 3] This figure shows the relationship between the types of biomass raw materials, the atomic ratio, and the expansion rate when the compressive load is removed. [Modes for carrying out the invention]

[0015] The following describes embodiments of the present invention (hereinafter referred to as "these embodiments"). Note that the following description illustrates an example of these embodiments, and the present invention is not limited to these embodiments.

[0016] The inventors conducted diligent research to solve the above-mentioned problems and obtained the following findings. Specifically, the biomass char for stamp-charge type coke ovens according to this embodiment (hereinafter referred to as biomass char) has different expansion rates when the compressive load is removed depending on the degree of carbonization, and the expansion rate when the compressive load is removed is extremely large in a specific carbonization state. When biomass char in such a specific carbonization state is mixed with coal, which is the main raw material for coal cake to be carbonized in a stamp-charge type coke oven, and molded under compressive force, the biomass char expands greatly as the compressive load is removed. As a result, density variations occur inside the coal cake after the load is removed, and the strength of the coal cake is significantly reduced.

[0017] The inventors have found that even biomass charcoal in a specific carbonized state can suppress the adverse effect on the strength of coal cakes when it is granulated, blended with coal, and uniformly mixed. The adverse effect on the strength of coal cakes means a decrease in the strength of coal cakes. Further, it has been found that when using seed shell charcoal as biomass charcoal, the decrease in the strength of coal cakes can be further suppressed as compared with the case of using other biomass charcoals. This is because the expansion rate of seed shell charcoal is small compared to other biomass charcoals. Incidentally, biomass charcoal in a specific carbonized state may be inevitably produced due to restrictions on heating devices for heating and carbonizing biomass raw materials and restrictions on the operating conditions of heating devices. Also, biomass charcoal in a specific carbonized state may be suitable for use in other equipment within a steel mill. In the latter case, it may be possible to intentionally produce biomass charcoal in a specific carbonized state suitable for use in such other equipment. Examples of such other equipment include top-charge coke ovens.

[0018] FIG. 1 is a flowchart for explaining a method for producing biomass charcoal for a stamp-charge coke oven according to the present embodiment and a method for producing coke. In the flowchart shown in FIG. 1, first, biomass charcoal to be blended with the blend coal of coal cakes to be carbonized and dry-distilled in a stamp-charge coke oven (not shown) is produced by carbonizing a biomass raw material (step S1, carbonization step). Here, the stamp-charge coke oven refers to a coke oven in which a coal cake having a size slightly smaller than that of the carbonization chamber is charged into the carbonization chamber and coke is produced by dry-distilling the coal cake. Coke produced in a stamp-charge coke oven may be referred to as stamp-charge coke (hereinafter simply referred to as coke). The coal cake is produced by compressing and molding the blend coal into a block shape having a size slightly smaller than that of the carbonization chamber by a stamping device arranged on the side of the carbonization chamber. The blend coal of the present embodiment is a blend coal containing coal and biomass charcoal, and the blending ratio of the biomass charcoal is preferably about 10 mass% (hereinafter referred to as “%”) or less.

[0019] (Biomass raw material) Biomass raw materials refer to organic industrial resources derived from animals and plants. That is, biomass raw materials mean products produced in industrial fields such as agriculture, forestry, livestock, and fisheries, as well as those of the wastes generated in the production process of said products that can be used as industrial resources.

[0020] Among the biomass raw materials produced in each industrial field, biomass raw materials derived from agriculture and forestry are suitable as raw materials for coke, that is, raw materials for stamp-charged coke. This is because biomass raw materials derived from agriculture and forestry have less ash content compared to biomass raw materials produced in other industrial fields, and also because their quality, production volume, and distribution volume are stable.

[0021] Biomass raw materials derived from agriculture include the residues generated when producing plants for food and fuel, and it is economically preferable to use these as raw materials for biomass charcoal. Specifically, examples of biomass raw materials derived from agriculture include rice husks, wheat straw, rice straw, sugarcane bagasse, PKS, EFB, palm trunk, walnut shell, coconut shell, pistachio shell, cashew nut shell, etc. PKS is palm husk, EFB is palm frond, and palm trunk is the xylem of the palm tree.

[0022] Among the biomass raw materials derived from agriculture, the parts classified as seed husks are particularly preferable. The parts classified as husks of said nuts and seeds are hereinafter referred to as seed husks. Specifically, it is particularly preferable to use seed husks such as PKS, walnut shell, coconut shell, pistachio shell, etc. as biomass raw materials. This is because these seed husks generally have a small expansion rate when unloading compressive force.

[0023] Biomass raw materials derived from forestry include woody biomass composed of coniferous trees such as cedar, pine, and cypress, and broad-leaved trees such as zelkova, birch, and eucalyptus. The part of the wood is not limited. Also, biomass raw materials derived from forestry include thinned wood and construction waste, and it is economically preferable to use these as raw materials for biomass charcoal.

[0024] (Biomass raw material carbonization method) In step S1, biomass charcoal is produced by carbonizing the biomass raw material by heat treatment. The heat treatment of the biomass raw material is preferably carried out in an atmosphere in which the supply of oxygen to the biomass raw material is cut off. For example, it is preferable to carry out the heat treatment in a container in which the inflow of air into the container is inhibited and an inert gas flows. That is, it is preferable to heat treat the biomass raw material in a non-oxidizing atmosphere. The heating of the biomass raw material may be carried out by heating the container and transferring heat from the container.

[0025] The heat treatment temperature and time used to carbonize biomass raw materials should be adjusted appropriately according to the type of biomass raw material so that the atomic ratio H / C (the ratio of hydrogen atoms to carbon atoms) falls within a predetermined range. For example, the atomic ratio H / C of biomass charcoal can be determined by carbonizing biomass raw materials at different heat treatment temperatures and times. A table summarizing the atomic ratio H / C for each heat treatment temperature and time is also created. Such tables are prepared for each type of biomass raw material. By using the above tables, the heat treatment temperature and time required to produce biomass charcoal with the desired atomic ratio H / C can be determined. The atomic ratio H / C is an indicator of the degree of carbonization of biomass charcoal produced by heat treatment of biomass raw materials. A smaller atomic ratio H / C indicates a more advanced carbonization.

[0026] In this embodiment, the atomic ratio H / C of biomass charcoal is greater than 0.25 and less than 0.45 (0.25 <H / C<0.45)である。

[0027] (Properties of biomass charcoal based on atomic ratio H / C) Biomass charcoal with an atomic ratio H / C in the range of 0.45 to 1.10 has the characteristics that compared with biomass charcoal with an atomic ratio H / C smaller than this range, carbonization has not progressed significantly and it is prone to creep deformation. When this biomass charcoal is compressed and held in a compressed state, creep deformation occurs, and as the amount of creep deformation increases, the compression load decreases. As a result, the amount of elastic deformation decreases, and the expansion, that is, the expansion rate, corresponding to the amount of elastic deformation when the compression force is removed becomes smaller. Therefore, when this biomass charcoal is blended as a raw material for coal cakes, high-strength molded products can be manufactured. The above-mentioned creep deformation means that when a certain load is applied, it gradually deforms.

[0028] Biomass charcoal with an atomic ratio H / C in the range of 0.01 to 0.25 has the characteristics that compared with biomass charcoal with an atomic ratio H / C larger than this range, carbonization has progressed relatively, and the elastic constant is large. Because the elastic constant of this biomass charcoal is large, the expansion rate when the compression force is removed is small. Therefore, when this biomass charcoal is blended as a raw material for coal cakes, high-strength molded products can be manufactured.

[0029] In contrast, biomass charcoal with an atomic ratio H / C exceeding 0.25 and less than 0.45 (0.25 < H / C < 0.45) is less prone to creep deformation because carbonization has progressed more than that of biomass charcoal with an atomic ratio H / C in the range of 0.45 to 1.10. On the other hand, because carbonization has not progressed as much as that of biomass charcoal with an atomic ratio H / C in the range of 0.01 to 0.25, the elastic constant is small. Therefore, the expansion rate when the compression force is removed becomes large, and when this biomass charcoal is blended as a raw material for coal cakes, density variations occur inside the coal cake after unloading, and the strength of the coal cake significantly decreases.

[0030] Generally, when the heat treatment time is constant, the higher the heat treatment temperature of the biomass raw material, the lower the atomic ratio H / C becomes. For example, if PKS is used as the biomass raw material and heat treatment is performed at 300-400°C, the atomic ratio H / C can be adjusted to a range of 0.45-1.10. If PKS is used as the biomass raw material and heat treatment is performed at 400-600°C, the atomic ratio H / C can be adjusted to a range of over 0.25 and less than 0.45. Furthermore, if PKS is used as the biomass raw material and heat treatment is performed at 600-1000°C, the atomic ratio H / C can be adjusted to a range of 0.01-0.25.

[0031] The heat treatment of biomass raw materials can be carried out using conventionally known heating devices such as rotary kilns, fluidized bed furnaces, electric furnaces, screw furnaces, shaft furnaces, and carbonization furnaces. Furthermore, the atomic ratio H / C mentioned above is calculated by quantifying the carbon atoms and hydrogen atoms in the biomass coal and obtaining the results from these quantifications. The quantification of carbon atoms and hydrogen atoms in biomass coal can be carried out in accordance with the "Methods for Elemental Analysis of Coal and Coke" specified in JIS, JIS M 8813:2006.

[0032] Next, the biomass charcoal produced by carbonizing biomass raw materials is crushed to a particle size smaller than that of the coal, which is the main raw material of the coal cake (Step S2, crushing step). The biomass charcoal in the carbonized state in this embodiment has a high expansion rate. Therefore, if the particle size of the coal, which is the main raw material of the coal cake, and the biomass charcoal are about the same, when the blended coal, which is a mixture of coal and biomass charcoal, is compressed and then unloaded, the biomass charcoal particles and the parts where the biomass charcoal particles are unevenly distributed will expand locally and significantly. This causes variations in density inside the coal cake after unloading, leading to a decrease in the overall strength of the coal cake. By finely granulating the biomass charcoal in this embodiment, the biomass charcoal can be uniformly mixed throughout the coal cake, and the amount of expansion per biomass charcoal particle can be reduced. This reduces the density variation inside the coal cake after unloading and suppresses the decrease in coal cake strength.

[0033] (Method for crushing biomass charcoal) The apparatus and methods for crushing biomass charcoal are not limited. For example, biomass charcoal may be crushed using a crushing device such as a hammer crusher, ball mill, or cutter mill. Furthermore, it is preferable to crush the biomass charcoal in such a way that the mass proportion of particles with a particle size of 3 mm or less is 90% or more, and the mass proportion of particles with a particle size of 1 mm or less is 65% or more.

[0034] Here, "a proportion of particles 3 mm or smaller is 90% or more" means that when sieving is performed using a sieve with a 3 mm mesh opening, the mass ratio of biomass coal that passes through the sieve to the total amount of crushed biomass coal is 90% or more. Similarly, "a proportion of particles 1 mm or smaller is 65% or more" means that when sieving is performed using a sieve with a 1 mm mesh opening, the mass ratio of biomass coal that passes through the sieve to the total amount of crushed biomass coal is 65% or more. Note that the particle size of coal, the main raw material for coal cake, is approximately 3 mm. The order of carbonization and crushing of the biomass raw material can be reversed and should be determined according to the heating and crushing equipment.

[0035] Next, the crushed biomass coal and coal are mixed in a predetermined ratio (Step S3, mixing process). This produces the blended coal, which is the raw material for coal cake. Preferably, the proportion of biomass coal in the blended coal is 10% or less. This is to reduce the likelihood of defects occurring due to the separation of the coal-derived portion and the biomass coal-derived portion of the coke after production. In other words, it is to suppress the decrease in strength of stamp-charge type coke.

[0036] Coal, the main raw material for coke, is crushed using a hammer crusher or similar device so that at least 70% of the particles are 3 mm or smaller. In addition to these raw materials, oil coke, pitch, other raw materials mainly composed of carbon, and carbides obtained by heating these other raw materials may be blended into the coal mixture.

[0037] The apparatus and method for mixing the various materials in the blended coal are not limited. It is generally preferable to use a mixer, similar to those used in coke plants, to uniformly mix the materials. Alternatively, the materials in the blended coal may be placed on a conveyor belt, and the fluid flow generated when they move from one conveyor belt to another may uniformly mix the materials. In other words, as the materials flow from one conveyor belt to another, each material generates a different fluid flow from the others. This ensures that the materials are uniformly mixed.

[0038] After mixing each material, it is preferable to adjust the moisture content of the blended coal. Moisture content adjustment can be achieved by drying the blended coal using a coal humidity control facility, or by spraying water onto the blended coal from a nozzle. For the purpose of maximizing the strength of the coal cake, the moisture content of the blended coal after mixing is preferably 9-12% of the total mass of the blended coal including moisture.

[0039] Following step S3, the blended coal is compressed and molded to produce a coal cake slightly smaller than the dimensions of the carbonization chamber (step S4, stamping process). The coal cake is produced by a conventionally known drop-weight impact type stamping device, which compacts the blended coal by dropping a weight onto it. The coal cake is then charged into the carbonization chamber by being pushed in from the side by a charging device. After that, the coal cake is carbonized at a temperature of approximately 900°C or higher to produce coke (step S5, carbonization process).

[0040] (Effects / Actions) When coal cake is charged into the carbonization chamber, it is subjected to vibrations and shocks associated with the operation of the charging device. If the strength of the coal cake is low, operational problems may occur, such as the coal cake collapsing due to its own weight or the aforementioned vibrations and shocks. However, the biomass coal in this embodiment, although more elastically deformable than biomass coal in other carbonization states, is finer-grained than the coal, which is the main raw material of the coal cake, and is uniformly mixed throughout the coal cake. Therefore, after the compressive force applied during the production of the coal cake is removed, the expansion of the biomass coal occurs uniformly throughout the coal cake. In other words, there is little variation in the density of the coal cake after removal of the load. As a result, the decrease in the strength of the coal cake can be suppressed. This makes it possible to prevent the collapse of the coal cake due to its own weight or vibrations and shocks associated with the operation of the charging device when charging the coal cake into the carbonization chamber, and to prevent the occurrence of operational problems caused by this. Furthermore, by replacing part of the coal used as a raw material for coal cake with biomass coal to produce coke, it is possible to contribute to reducing CO2 emissions. In addition, if seed husks are used as a raw material for biomass coal, the decrease in the strength of the coal cake and the occurrence of operational problems due to the collapse of the coal cake can be further suppressed. [Examples]

[0041] The following describes embodiments of the present invention. Coal cake was produced by blending carbonized biomass raw materials with coal similar to that used in actual operation, in the same manner as in this embodiment. A strength test was performed on the coal cake to evaluate the effect of biomass char on the coal cake strength. The coal used had a degree of coalification (Ro) of approximately 0.96 and was crushed so that the proportion of particles with a particle size of 3 mm or less was 70% by mass (hereinafter simply referred to as %). 5% biomass char was blended with 100% coal in a mixer, and then the moisture content of the blended coal was adjusted to 10%. The biomass char was crushed so that the proportion of particles with a particle size of 3 mm or less was 65-75%, that is, similar to that of coal.

[0042] Using the aforementioned coal blend, a coal cake was manufactured following the procedure below. First, approximately 200g of coal blend was placed in a metal mold with an inner diameter of 10cm and a height of 20cm. A 9kg rammer was dropped onto the surface of the coal blend from a height of 30cm 10 times, compacting the coal blend with the impact of the rammer. This was repeated a total of 10 times to produce a coal cake with a diameter of 10cm, a height of 20cm, and weighing approximately 2kg.

[0043] Subsequently, the coal cake was removed from the metal mold and its strength was measured using the unconfined compressive strength specified in JIS A 1216:2020. The strength of coal cake produced using only coal was used as the standard strength. The strength of coal cake produced by blending coal with biomass coal was divided by the standard strength to calculate the strength ratio of coal cake produced by blending coal with biomass coal to the standard strength. The strength of each coal cake was then evaluated based on this strength ratio.

[0044] Figure 2 shows the relationship between the type of biomass raw material, the atomic ratio H / C, and the coal cake strength ratio. Note that if the coal cake strength ratio is 85% or higher, the effect of blending biomass coal with coal on the coal cake strength is small, and it can be considered that it can be used without operational problems. If the coal cake strength ratio is 90% or higher, the effect of blending biomass coal with coal on the coal cake strength, i.e., the reduction in coal cake strength, can be considered to be almost negligible.

[0045] As shown in Figure 2, the strength ratio of coal cakes made from biomass coal with an atomic ratio (H / C) exceeding 0.25 and below 0.45 was below 85%. Therefore, using such coal cakes in actual operations may cause operational problems such as the collapse of the coal cakes.

[0046] Therefore, biomass coal with an atomic ratio H / C between 0.25 and 0.45 was crushed into fine particles using a crushing device. Specifically, the biomass coal was crushed using a crushing device so that 90% or more of the total amount of biomass coal had a particle size of 3 mm or less, and 65% or more had a particle size of 1 mm or less. After that, coal cake was produced as described above, and the strength of the coal cake was measured. In addition, the strength ratio of coal cake produced by blending biomass coal with coal was calculated to the strength of coal cake produced using only coal. Table 1 summarizes the types of biomass raw materials used in each of Invention Examples 1 to 6 and Comparative Examples 1 to 3, the atomic ratio H / C of the biomass coal, and the strength ratios of the coal cakes for each of Invention Examples 1 to 6 and Comparative Examples 1 to 3.

[0047] [Table 1]

[0048] As shown in Table 1, by granulating biomass coal with an atomic ratio H / C between 0.25 and 0.45 as described above, the strength ratio of the coal cake exceeded 85%. This is thought to be because granulating the biomass coal allowed for uniform mixing throughout the coal cake, and after the compressive load was removed, the expansion of the biomass coal occurred uniformly throughout the coal cake. In other words, the biomass coal was not concentrated in specific areas, and did not expand significantly in those areas. Therefore, it was found that the coal cakes of Invention Examples 1 to 6 could be used without operational problems.

[0049] Figure 3 shows the relationship between the type of biomass raw material, the atomic ratio (H / C), and the expansion rate when the compressive load is removed. The expansion rate was measured under the following conditions: Each biomass char was crushed and sieved to adjust the particle size to 44-74 μm. 0.85 g of the biomass char with this particle size adjustment was placed in a 16 mm diameter mold and compressed at a pressure of 100 MPa for 5 minutes. After that, the pressure applied to the biomass char was removed. The difference between the filling height of the biomass char in the mold before the pressure was removed and the filling height of the biomass char in the mold after the pressure was removed, i.e., the expansion width of the biomass char with the removal of the pressure, was determined. Then, the expansion width was divided by the filling height of the biomass char in the mold before the pressure was removed, and this was taken as the expansion rate of the biomass char.

[0050] In Figure 3, when comparing biomass coals with similar atomic ratios (H / C), the expansion rate of biomass coal made from PKS was lower than that of biomass coal made from cedar wood, as shown in Figure 3. This difference in expansion rates is thought to reflect the differences in the inherent properties of the biomass raw materials. In other words, by using biomass raw materials with inherently low elastic constants, such as PKS, it is possible to produce biomass coal that expands less when the compressive load is removed, making it easier to mold into a high-strength coal cake. [Explanation of Symbols]

[0051] S1 Carbonization process S2 Grinding process S3 Mixing process S4 Stamping Process S5 Carbonization process

Claims

1. A method for producing biomass charcoal for a stamp-charge coke oven, which is mixed together with coal in coal cake that is charged into the stamp-charge coke oven and carbonized, A carbonization process in which biomass raw materials are carbonized such that the atomic ratio H / C, which is the ratio of hydrogen atoms to carbon atoms, is greater than 0.25 and less than 0.45, A method for producing biomass charcoal for a stamp-charge type coke oven, comprising a grinding step of grinding the biomass charcoal for a stamp-charge type coke oven, which is produced by carbonizing biomass raw materials in the carbonization step, so that the proportion of particles with a particle size of 3 mm or less is 90% by mass or more, and the proportion of particles with a particle size of 1 mm or less is 65% by mass or more.

2. The method for producing biomass charcoal for a stamp-charge type coke oven according to claim 1, wherein the carbonization step involves carbonizing the biomass raw material at a temperature of 400 to 600°C.

3. The method for producing biomass charcoal for a stamp-charge type coke oven according to claim 1 or 2, wherein the biomass raw material to be carbonized in the carbonization step is seed husks.

4. The method for producing biomass charcoal for a stamp-charge type coke oven according to claim 3, wherein the seed husk is at least one of palm kernel shells, walnut shells, coconut shells, pistachio shells, and cashew nut shells.

5. A stamping step to produce a coal cake by stamping a blended coal containing biomass charcoal for a stamp-charge type coke oven prepared by the method for producing biomass charcoal for a stamp-charge type coke oven according to claim 1 or 2 and coal, A method for producing coke, comprising a carbonization step of producing coke by charging the coal cake produced in the stamping step into a stamp-charge type coke oven and carbonizing it.

6. A stamping step to produce a coal cake by stamping a blended coal containing biomass coal for a stamp-charge type coke oven prepared by the method for producing biomass coal for a stamp-charge type coke oven described in Claim 3 and coal, A method for producing coke, comprising a carbonization step of producing coke by charging the coal cake produced in the stamping step into a stamp-charge type coke oven and carbonizing it.

7. A stamping step to produce a coal cake by stamping a blended coal containing biomass coal for a stamp-charge type coke oven prepared by the method for producing biomass coal for a stamp-charge type coke oven described in Claim 4 and coal, A method for producing coke, comprising a carbonization step of producing coke by charging the coal cake produced in the stamping step into a stamp-charge type coke oven and carbonizing it.

8. Biomass charcoal for stamp-charge coke ovens, which is mixed together with coal in coal cake that is carbonized in a stamp-charge coke oven, Biomass charcoal for stamp-charge type coke ovens, wherein the atomic ratio H / C (the ratio of hydrogen atoms to carbon atoms) is greater than 0.25 and less than 0.45, the proportion of particles with a particle size of 3 mm or less is 90% by mass or more, and the proportion of particles with a particle size of 1 mm or less is 65% by mass or more.

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