Apparatus for manufacturing molded charcoal and method for manufacturing molded charcoal

Abstract

A molten charcoal manufacturing apparatus and a method for manufacturing molten charcoal are provided that can suppress the adhesion of raw materials to recesses on the surface of the molding roll. [Solution] The molded coal manufacturing apparatus is used in a molded coal manufacturing process in which molded coal is produced by molding a molding raw material (6) containing kneaded coal powder and a binder, and comprises a molding roll (2) that pressurizes and molds the molding raw material, and a spraying device (3) installed on the outer circumference of the molding roll (2) that sprays atomized liquid droplets into recesses on the surface of the molding roll (2).

Description

Technical Field

[0001] The present disclosure relates to an apparatus for manufacturing formed coke and a method for manufacturing formed coke.

Background Art

[0002] In the iron-making process, for the purpose of reducing raw material costs, improving the quality of intermediate products, and reducing the environmental load by preventing scattering, various powdered raw materials may be briquetted (solidified into a specific shape by being hardened under high pressure) and used. For example, ore may be crushed, sorted, and compression-molded for use as a high-quality raw material. Also, for example, the bulk density and air permeability may be improved by compression-molding powders of coal and iron ore. Also, for example, dust scattering may be prevented by compression-molding the input dust to a converter.

[0003] In the production of coke, for reasons such as improving productivity, pretreatment is often performed on the coal, which is the raw material for coke, before charging it into the coke oven. As such pretreatment, a technique of using all or part of the coal charged into the coke oven as formed coke (formed coke blending technique) is known. Inside the formed coke, coal particles are in proximity to each other. Therefore, by charging formed coke into the coke oven, the charging density of the coal can be improved. As a result, the strength of the coke is improved, and the amount of strongly caking coal used can also be reduced. Furthermore, even coal of lower quality can be used. Generally, formed coke is produced by crushing coal into a powder as a raw material, kneading (or mixing) it with a binder, and pressure-molding it with a molding machine. In order to suppress pulverization during transportation, a certain degree of strength is required for the formed coke.

[0004] Here, many techniques have been proposed regarding the production of formed coke. For example, Patent Document 1 discloses a technique of producing formed coke by dehydrating and heating low-grade coal and then compression-molding it, and further performing an oxidation treatment. For example, Patent Document 2 discloses a technique of producing formed coke by molding coal with a double-roll molding machine.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 59-161491 [Patent Document 2] Patent No. 4265422 [Patent Document 3] Japanese Patent Publication No. 2001-259787 [Patent Document 4] Japanese Patent Publication No. 2010-82650 [Patent Document 5] Patent No. 6151169 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the production of molded coal, a molding machine is used to produce high-density molded products compressed under high pressure. However, depending on the operating conditions during production, broken raw materials may adhere to the roll cups (the molds and recesses on the outer surface of the molding rolls). When the adhesion of raw materials to the roll cups increases, the raw materials cannot enter those areas, resulting in the production of plate-shaped molded products. Plate-shaped molded products are more prone to pulverization than normal rounded molded products and are unsuitable as blast furnace raw materials. Therefore, the yield of molded products decreases when raw materials adhere to the roll cups. For example, Patent Documents 1 and 2 do not disclose methods to improve such a decrease in yield.

[0007] There are various possible causes for adhesion to the roll cup, but it is presumed that the high temperature of the raw material during molding (approximately 160°C) causes the binder to soften, leading to the binder burning onto the roll surface or adhering to the roll cup, resulting in cracking of the molded product. To improve the release properties of the roll cup of the molding machine, methods have been proposed such as forming a thin film with good release properties on the surface of the molding machine (e.g., Patent Document 3) and applying a lubricant such as wax (e.g., Patent Document 4). In addition, a method has been proposed to cool the roll by continuously blowing cold air onto it to lower the temperature of the raw material during molding (e.g., Patent Document 5).

[0008] However, since the molded product is formed under high pressure and raw materials that are likely to cause wear on the roll surface are used, the method in Patent Document 3 loses its mold release effect in a short time due to surface wear. Furthermore, the method in Patent Document 4 uses a special chemical as a lubricant, which raises concerns about increased costs. In addition, because the binder is lipophilic, the lubricant may enter the binder, potentially degrading the quality of the molded product after carbonization. The method in Patent Document 5 is difficult to control because the optimal temperature range is a narrow range of 70°C to 80°C, and it is thought that the amount of refrigerant required will also increase with the recent increase in the size of molding machines.

[0009] In view of these circumstances, the purpose of this disclosure is to provide a molded charcoal manufacturing apparatus and a molded charcoal manufacturing method that can suppress the adhesion of raw materials to recesses on the surface of the molding roll. [Means for solving the problem]

[0010] (1) A charcoal manufacturing apparatus according to one embodiment of the present disclosure, A molten coal manufacturing apparatus used in a molten coal manufacturing process that produces molten coal by molding a molding raw material containing kneaded coal powder and a binder, A molding roll for molding the aforementioned molding material under pressure, The system includes a spraying device installed on the outer circumference of the molding roll, which sprays atomized liquid droplets into recesses on the surface of the molding roll.

[0011] (2) As one embodiment of the present disclosure, in (1), The spraying device is installed within a range of 135° to 225° in the rotational direction of the molding rolls, with 0° being the position where the gap between the pair of molding rolls is minimized.

[0012] (3) In one embodiment of the present disclosure, in (1) or (2), The spray flow rate, which is the flow rate of the droplets sprayed by the spraying device, is set within the range of 0.3 [L / min] to 0.7 [L / min].

[0013] (4) In one embodiment of the present disclosure, in any of (1) to (3), The droplet diameter, which is the diameter of the droplets sprayed by the spraying device, is set within the range of 30 μm to 300 μm.

[0014] (5) A method for producing molded charcoal according to one embodiment of the present disclosure is: A molded coal manufacturing apparatus comprising a molding roll for pressurizing and molding a molding raw material containing kneaded coal powder and a binder, and a spraying device, includes a molded coal manufacturing process for molding the molding raw material to produce the molded coal, The spraying device is installed on the outer circumference of the molding roll and sprays atomized droplets into recesses on the surface of the molding roll. [Effects of the Invention]

[0015] According to this disclosure, it is possible to provide a molded charcoal manufacturing apparatus and a molded charcoal manufacturing method that can suppress the adhesion of raw materials to recesses on the surface of the molding roll. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 shows an example of the configuration of a molded charcoal manufacturing apparatus according to one embodiment of the present disclosure. [Figure 2] Figure 2 illustrates the relationship between the installation angle of the spraying device and the yield. [Figure 3]FIG. 3 is a diagram illustrating the relationship between the spray flow rate and the yield. [Figure 4] FIG. 4 is a diagram illustrating the relationship between the droplet diameter and the yield. MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, a manufacturing apparatus for formed charcoal and a manufacturing method for formed charcoal according to an embodiment of the present disclosure will be described with reference to the drawings.

[0018] Here, each drawing is schematic and may differ from the actual one. Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present disclosure, and do not specify the configuration to be the following ones.

[0019] Figure 1 shows an example of the configuration of a molten coal manufacturing apparatus according to this embodiment. As shown in Figure 1, coal powder crushed to a predetermined particle size and a binder are fed into a kneading mixer 1 in a predetermined mixing ratio, and kneading is carried out at a raw material temperature of 160°C for a predetermined time. The kneading mixer 1 may be a known apparatus for kneading (or mixing) raw materials. Then, the molded raw material 6 containing the kneaded coal powder and binder is pressed and molded by a double-roll molding machine having a pair of molding rolls 2 to produce a molded product 5 (molten coal in this embodiment). A recess (roll cup) is formed on the outer surface of the molding roll 2, and the fed raw material is pressed and molded according to the shape of the molding roll 2 (in the example of Figure 1, into a round shape due to the recess). Here, the double-roll molding machine is an example of a molten coal manufacturing apparatus. In other words, a molded coal manufacturing apparatus, comprising a molding roll 2 that pressurizes and molds the molding raw material 6, and a spraying device 3, performs a molded coal manufacturing process in which molded coal is produced by molding the molding raw material 6. The manufactured molded coal is discharged onto a conveyor, travels along the conveyor, and is fed into a coke oven via a hopper or the like. Here, the spraying device 3, which is part of the molded coal manufacturing apparatus, is installed on the outer circumference of the molding roll 2 and sprays atomized droplets into the recesses on the surface of the molding roll 2. The spraying device 3 may have a spray nozzle to spray droplets onto the surface of the molding roll 2. In this embodiment, the droplets to be sprayed are water droplets (i.e., the liquid to be sprayed is water). The type of spray nozzle may be a single-fluid system using only water, or a gas-liquid mixed system, but is not particularly limited. A pressure adjustment plate 4 may also be used. The pressure adjustment plate 4 is a partition plate installed on a pair of molding rolls 2, and adjusts the pressure during molding by increasing or decreasing the amount of raw material being fed in.

[0020] The powder used as the molding raw material 6 may include coal powder, ore powder, and other converter dust, but coal powder is preferred in the production of molded coal in the steelmaking process. The particle size of the coal powder is not particularly limited, but the finer the coal powder, the stronger the molded product 5 will be. Preferably, 80% or more by mass of coal powder has a particle size of 3 mm or less, and more preferably 90% or more by mass has a particle size of 3 mm or less. Here, when using coal powder with a particle size of 3 mm or less that is less than 80% by mass, it is preferable to adjust it to satisfy the above ratio by crushing or mixing with other coal powder of a finer particle size. Here, the particle size may be the diameter if the object being measured is spherical, but if it is a round shape that is not spherical, it may be defined as the longest diameter. The particle size may be measured by known methods depending on the size of the object. For example, if the object is coal powder, it may be measured by processing such as boundary enhancement on an image, and if the object is fine particles, it may be measured using the intensity of scattered light.

[0021] In this embodiment, soft pitch (SOP) and asphalt pitch (ASP) were used as binders for the molding raw material 6. Soft pitch and asphalt pitch were added in amounts of 5% by mass and 3.5% by mass, respectively, relative to the weight of the raw material.

[0022] The following experiment was conducted to verify the relationship between the yield of the manufactured molded coal and the installation position of the spraying device 3. Here, since the spraying device 3 is installed on the outer circumference of the circular molding roll 2, the installation position can be determined by an angle with respect to a reference point on the molding roll 2. Hereafter, the installation position of the spraying device 3, expressed as an angle, will be referred to as the installation angle.

[0023] The molded coal manufacturing process was carried out using the molded coal manufacturing apparatus shown in Figure 1, and molded coal was produced. The molded coal was recovered at the discharge position on the exit side of the molding roll 2, and the yield was determined by calculating the weight of the molded coal relative to the weight of the input molding raw material 6. In addition, the installation angle of the spraying device 3 was changed from 90° to 270°. Figure 2 shows the relationship between the installation angle of the spraying device 3 and the yield. The installation angle of the spraying device 3 is defined as the angle in the rotational direction of the molding roll 2 (see θ in Figure 1), with the position where the gap between the pair of molding rolls 2 is smallest being 0° (see s in Figure 1). As shown in Figure 2, a high yield (over 80%) was obtained by setting the installation angle within the range of 135° to 225° (see a in Figure 1). When the installation angle of the spraying device 3 is less than 135°, the sprayed water falls due to gravity, so a thin film of water is not formed in the recesses on the surface of the molding roll 2, and the molding raw material 6 adheres to the recesses. Furthermore, if the installation angle of the spraying device 3 exceeds 225°, the sprayed water will directly mix with the molding material 6, reducing the yield. Therefore, it is preferable that the spraying device 3 be installed at an angle within the range of 135° to 225°.

[0024] Furthermore, the following experiment was conducted to verify the relationship between the yield of the manufactured molded coal and the spray flow rate, which is the flow rate of droplets sprayed by the spraying device 3. The molded coal manufacturing process was carried out using the molded coal manufacturing apparatus shown in Figure 1, and molded coal was produced. The molded coal was recovered at the discharge position on the exit side of the molding roll 2, and the yield was determined by calculating the weight of the molded coal relative to the weight of the input molding raw material 6. In addition, the spray flow rate of the spraying device 3 was changed from approximately 0 to 1.4 [L / min]. Figure 3 shows the relationship between the spray flow rate of the spraying device 3 and the yield. As shown in Figure 3, a high yield (over 80%) was obtained by setting the spray flow rate within the range of 0.3 [L / min] to 0.7 [L / min].

[0025] Furthermore, the following experiment was conducted to verify the relationship between the yield of the manufactured molded charcoal and the droplet diameter, which is the diameter of the droplets sprayed by the spraying device 3. The molded charcoal manufacturing process was carried out using the molded charcoal manufacturing apparatus shown in Figure 1, and molded charcoal was manufactured. The molded charcoal was recovered at the discharge position on the exit side of the molding roll 2, and the yield was determined by calculating the weight of the molded charcoal relative to the weight of the input molding raw material 6. In addition, the droplet diameter of the spraying device 3 was changed from approximately 5 μm to 1000 μm. Figure 4 shows the relationship between droplet diameter and yield. As shown in Figure 4, a high yield (over 80%) was obtained by setting the droplet diameter within the range of 30 μm to 300 μm. When the droplet diameter is less than 30 μm, the molding roll 2 is rotating, making it difficult for the sprayed droplets to reach the bottom of the recesses. Also, when the droplet diameter exceeds 300 μm, the weight of the droplets themselves makes it difficult for the sprayed droplets to reach the bottom of the recesses. Therefore, it is preferable to set the droplet diameter within the range of 30 μm to 300 μm.

[0026] The effects of this disclosure will be described in detail below based on the examples provided, but this disclosure is not limited to these examples.

[0027] As an example of the invention, molded charcoal was produced by carrying out the molded charcoal manufacturing process using the molded charcoal manufacturing apparatus shown in Figure 1. The molded charcoal was recovered at the discharge position on the exit side of the molding roll 2, and the yield was determined by calculating the weight of the molded charcoal relative to the weight of the input molding raw material 6. As comparative examples, the yield was determined for the case where the spraying device 3 was not used (Comparative Example 1) and for cases where the installation angle, spray flow rate, or droplet diameter was outside the above range (Comparative Examples 2-4). The "Number" in Table 1 is a number to identify each example, with the classification of it as an example of the invention or a comparative example added. The "Condition" in Table 1 indicates the settings for the installation angle, spray flow rate, and droplet diameter of the spraying device 3. The "Yield" in Table 1 is the yield value calculated as described above.

[0028] As shown in Table 1, the comparative examples all show low yields due to the adhesion of the molding material 6 to the recesses. In contrast, the inventive examples, which use conditions set within the appropriate range described above, achieve high yields (80% or more).

[0029] [Table 1]

[0030] As described above, the molded charcoal manufacturing apparatus and molded charcoal manufacturing method according to this embodiment can effectively suppress the adhesion of raw materials to the recesses on the surface of the molding roll 2 by the above configuration. As a result, it is possible to avoid the production of molded charcoal with poor shape that is prone to pulverization, and the strength of the molded product 5 can be ensured, thereby improving the yield.

[0031] While embodiments of this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art will find it easy to make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are included within the scope of this disclosure.

[0032] As described above, the kneading and mixing machine 1 may be a device with a known configuration and is not limited to a specific type, but a horizontal kneader type is preferable, for example. The kneading and mixing machine 1 may also be a Henschel type mixer or a vertical paddle type device. However, since the Henschel type mixer performs batch kneading (mixing), if a large volume of processing is required, multiple units will need to be installed, increasing equipment costs. In the case of a vertical kneader, it only has the function of kneading, so a separate device is required for mixing. Therefore, the installation area and equipment costs increase.

[0033] Furthermore, the heating method during mixing in the mixing machine 1 may be, for example, a steam injection method, but is not limited thereto. As another example, microwave irradiation or the installation of a heat transfer medium around or inside the mixing machine 1 may be employed. The heat transfer medium may be an electric heater or a gas combustion device. The steam injection method can reduce costs compared to other methods because the heat source can be secured within the steelworks. Microwave irradiation can shorten the heating time compared to other methods. Electric heaters or gas combustion devices can handle higher temperature conditions compared to heating with steam. [Explanation of Symbols]

[0034] 1. Mixing machine 2. Molding Rolls 3 Spray device 4. Pressure regulating plate 5 Molded object 6 Molding raw materials

Claims

1. A molten coal manufacturing apparatus used in a molten coal manufacturing process that produces molten coal by molding a molding raw material containing kneaded coal powder and a binder, A molding roll for molding the aforementioned molding material under pressure, A molten charcoal manufacturing apparatus comprising: a spraying device installed on the outer circumference of the molding roll, which sprays atomized liquid droplets into recesses on the surface of the molding roll;

2. The molding charcoal manufacturing apparatus according to claim 1, wherein the spraying device is installed within a range of 135° to 225° in the rotational direction of the molding rolls, with the position where the gap between the pair of molding rolls is smallest being defined as 0°.

3. The molding charcoal manufacturing apparatus according to claim 1 or 2, wherein the spray flow rate, which is the flow rate of the droplets sprayed by the spraying device, is set within the range of 0.3 [L / min] to 0.7 [L / min].

4. The apparatus for producing molded charcoal according to claim 1 or 2, wherein the droplet diameter, which is the diameter of the droplets sprayed by the spraying device, is set within the range of 30 μm to 300 μm.

5. A molded coal manufacturing apparatus comprising a molding roll for pressurizing and molding a molding raw material containing kneaded coal powder and a binder, and a spraying device, includes a molded coal manufacturing process for molding the molding raw material to produce the molded coal, A method for manufacturing molded charcoal, wherein the spraying device is installed on the outer circumference of the molding roll and sprays atomized liquid droplets into recesses on the surface of the molding roll.

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