Method and apparatus for producing ferrocoke raw material

Abstract

To provide an efficient and novel method and apparatus for producing a ferrocoke raw material, taking into account improvement in molding yield in a molding step for agglomerating a raw material.SOLUTION: A method for producing a ferrocoke raw material according to the present invention comprises, in a process of mixing a molding raw material containing coal, an iron source raw material, and a binder, agglomerating the mixture with a double roll molding machine to form a molded product, and dry-distilling the molded product to produce ferrocoke, passing the mixed molding raw material between a primary gate, which is vertically movably installed on one roll of the double roll molding machine, and the one roll, then passing the mixed molding raw material between a secondary gate, which is vertically movably installed on a nip portion between the one roll and the other roll of the double roll molding machine, and the nip portion, supplying the mixed molding raw material to the double roll molding machine, and molding the mixed molding raw material with the double roll molding machine to produce the molded product.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing ferro-coke raw material in a process for producing ferro-coke for metallurgy from an iron source raw material such as iron ore and coal. [Background technology]

[0002] In order to efficiently operate a blast furnace, coal is carbonized in a coke oven to produce coke, and the coke is then charged into the blast furnace. The coke in the blast furnace serves various purposes, including as a spacer to improve ventilation within the furnace, as a reducing agent, and as a heat source. In recent years, a technique has been developed to obtain ferrocoke for metallurgy by mixing iron ore with coal in order to improve the reactivity of the coke (see, for example, Patent Document 1). Whether the ferrocoke raw material is rich in coal or rich in iron ore is determined arbitrarily depending on whether it is intended to replace coke or to be used as an iron source.

[0003] In the process of producing this ferro-coke, coal and iron ore need to be agglomerated in a molding machine. There are two types of agglomeration methods: one in which a binder is added to the raw materials and molding is performed at room temperature to about 250°C; and another in which the coal is softened and melted at a high temperature of 250°C or higher and molding is performed using the caking properties of the coal without adding a binder. Known examples of the former method include kneading coal, iron ore, and a binder in a kneading machine and then molding at room temperature (see, for example, Patent Document 2). Known examples of the latter method include mixing coal and iron ore, rapidly heating to 250°C or higher, and molding under pressure (see, for example, Patent Document 3). The agglomerated moldings are carbonized in a carbonization furnace to produce ferro-coke. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-15700 A (Claims) [Patent Document 2] JP-A-64-81889 (page 2) [Patent Document 3] JP 2005-53986 A (Claim 3) [Patent Document 4] JP 2009-235222 A (Claim 4) Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the production of ferro-coke involves a mixing process for mixing raw materials, a transport process for transporting the mixed raw materials to a molding machine, a molding process for agglomerating the agglomerates, and a subsequent process for carbonizing the agglomerates to obtain a ferro-coke product. In producing ferro-coke, the agglomerates must have high handling strength, and the strength of the carbonized ferro-coke product must also be high because it is fed into a blast furnace. However, the briquetting yield in the briquetting process is important in terms of production costs. However, while Patent Documents 1 to 3 discuss the briquetting temperature, the types of raw materials used, and auxiliary materials, they do not consider the briquetting yield.

[0006] Patent Document 4 proposes blending a powdery portion into the raw material at a specified ratio and using a double-roll molding machine to improve molding yield. However, powdery portions are defective products that are rejected as finished products during molding, and it is desirable to prevent their generation. Furthermore, controlling the molding pressure is an issue with double-roll molding machines. Generally, low molding pressure results in poor moldability, while excessive pressure reduces yield due to cracking. Therefore, there is a molding pressure at which yield is maximized. Furthermore, it is important to suppress deviations in molding pressure in the width direction. If the molding pressure deviation is high, even if the average pressure is appropriate, the proportion of molded products with local cracks or insufficient molding increases, reducing yield.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a new and efficient method and apparatus for producing ferro-coke raw materials, which takes into consideration an improvement in the molding yield in the molding step of agglomerating raw materials. [Means for solving the problem]

[0008] The method for producing ferro-coke raw material of the present invention is characterized in that, in a process for producing ferro-coke, a molding raw material including coal, an iron source raw material, and a binder is mixed and kneaded, and the resulting agglomerates are formed in a double-roll molding machine by carbonizing the resulting molded products, the mixed molding raw material is passed between a primary gate installed above one of the rolls of the double-roll molding machine so as to be able to rise and fall, and the roll, and then passed between a secondary gate installed above a kissing portion between the one roll and the other roll of the double-roll molding machine so as to be able to rise and fall, and the kissing portion, and then supplied to the double-roll molding machine, and molded in the double-roll molding machine to produce a molded product.

[0009] In the method for producing a ferro coke raw material of the present invention configured as described above, (1) The distance between the primary gate and one roll surface of the double roll molding machine is 20 to 60 mm; (2) The molding pressure of the double roll molding machine is set to 2.2 to 2.6 t / cm, and the deviation of the molding pressure in the width direction of the double roll molding machine is set to 0.3 t / cm or less. (3) The material of the primary gate and the secondary gate is austenitic stainless steel. This is considered to be a more preferable solution.

[0010] The present invention also provides an apparatus for producing ferro coke raw material, which kneads raw materials for molding, including coal, an iron source raw material, and a binder, and obtains molded products by agglomerating the raw materials in a double-roll molding machine, and is characterized in that it comprises a primary gate installed so as to be raised and lowered above one of the rolls of the double-roll molding machine, and a secondary gate installed so as to be raised and lowered above a kiss portion between the one roll and the other roll of the double-roll molding machine. [Effects of the Invention]

[0011] According to the method and apparatus for producing ferro-coke raw material of the present invention, the mixed raw material to be molded is passed through a primary gate and a secondary gate of a predetermined configuration before being molded in a double-roll molder, thereby optimizing the molding pressure and the deviation in the width direction, improving the molded product yield when producing molded products using the double-roll molder, and reducing the production cost. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an embodiment of a ferro coke production facility including a method and apparatus for producing a ferro coke raw material according to the present invention. [Figure 2] 1 is a schematic diagram showing an embodiment of a configuration that is a characteristic of a method and apparatus for producing a ferro-coke raw material according to the present invention. [Figure 3] 1 is a graph showing the relationship between the height between the primary gate and the double roll molding machine and the width-direction deviation of molding pressure in the present invention. [Figure 4] 1 is a graph showing the relationship between the width direction deviation of molding pressure and molding yield in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes in detail the embodiments of the present invention. Note that the following embodiments are intended to exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to that described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope defined in the claims.

[0014] <One embodiment of the method and apparatus for producing ferro-coke raw material according to the present invention> FIG. 1 is a schematic diagram showing one embodiment of a ferro-coke production facility including a method and apparatus for producing ferro-coke raw material according to the present invention. In the example shown in FIG. 1, coal 1 and iron-source raw material 2 are crushed to a predetermined particle size or less in a crusher (not shown) and then blended in a predetermined ratio. For example, the coal is crushed to 3 mm or less, and the iron-source raw material is crushed to 0.5 mm or less. Then, the coal and iron-source raw material are blended in a ratio of, for example, 60 to 90 mass % coal and 10 to 40 mass % iron-source raw material. Iron ore is mainly used as the iron-source raw material 2, but iron ore may be replaced by iron-source raw material by-products in steelworks, such as blast furnace dust, converter dust, and rolling sludge. Furthermore, multiple brands of iron ore and coal may be combined. In this embodiment, iron ore is used as the iron-source raw material 2.

[0015] The blended coal 1 and iron ore 2 are fed into the kneader 3. A binder is added to the kneader 3 from a binder tank 4. Commonly used binders include SOP (soft pitch), ASP (asphalt pitch), and ferrotar (a by-product produced during the carbonization process of ferro-coke), and one or more types can be used in combination. The binder is added from the binder tank 4 at the same time as the coal 1 and iron ore 2 are fed into the kneader 3, or during kneading. Through the above process, a mixed raw material for molding can be obtained.

[0016] The kneaded molding raw material is transferred via conveying equipment 5 to a double-roll molding machine 6, which is a high-pressure molding machine, and is subjected to high-pressure molding. Typical examples of the conveying equipment 5 include a belt conveyor, a flight conveyor, and a screw feeder. The double-roll molding machine 6 molds the kneaded molding raw material.

[0017] The briquettes (briquettes) formed by the double roll molding machine 6 are separated into an oversize portion 7 and an undersize portion 8 through a sieve, and the briquettes separated as the oversize portion 7 are supplied to a carbonization furnace 9, where they are carbonized to form ferro-coke. The briquetting yield is calculated by dividing the weight of the oversize portion 7 by the total weight of the oversize portion 7 and the undersize portion 8. An example of the shape of the briquettes is an oval shape with a major axis of 25 mm, a minor axis of 18 mm, and a depth of 6 mm.

[0018] The inventors discovered that there is an optimum molding pressure in the double-roll molding machine 6, because low molding pressure results in insufficient molding, while excessive molding pressure causes cracks. This led to the idea that optimizing the pressure and suppressing pressure deviation in the width direction is desirable from the perspective of improving the strength of the molded product.

[0019] In order to control these factors, the method and apparatus for producing a ferro-coke raw material of the present invention employs a primary gate that is installed above one of the rolls of the double-roll molding machine in a manner that allows it to rise and fall, and a secondary gate that is installed above the kissing portion between one roll and the other roll of the double-roll molding machine in a manner that allows it to rise and fall.

[0020] FIG. 2 is a schematic diagram showing one embodiment of a configuration characteristic of the manufacturing method and manufacturing apparatus for ferro-coke raw material of the present invention. In the example shown in FIG. 2, a primary gate 12 and a secondary gate 13 are provided between a double-roll molding machine 6, which is composed of a counterclockwise rotating conveying roll 6-1 and a clockwise rotating fixed roll 6-2, and a raw material hopper 11, which stores the mixed raw material for molding. Specifically, the primary gate 12 is arranged to be able to move up and down above the conveying roll 6-1 of the double-roll molding machine 6, and the secondary gate 13 is arranged to be able to move up and down above the kiss portion K between the conveying roll 6-1 and the fixed roll 6-2 of the double-roll molding machine 6. The elevation of the primary gate 12 and the secondary gate 13 is achieved by using a power cylinder (not shown) to change the height of the primary gate 12 and the secondary gate 13 while the raw material is being transported. Furthermore, both the primary gate 12 and the secondary gate 13 are composed of plate-shaped members formed across the entire width of the double-roll molding machine 6.

[0021] 2, by raising and lowering the primary gate 12, the thickness of the raw material layer in the width direction of the double roll molding machine 6 can be made uniform, and deviations in the molding pressure during molding by the double roll molding machine 6 can be suppressed. Furthermore, by raising and lowering the secondary gate 13, the amount of raw material supplied changes, and as a result, the absolute value of the molding pressure during molding by the double roll molding machine 6 can be controlled. If the gate height of the secondary gate 13 is high, a large amount of raw material is supplied, increasing the pressure, and if the gate height is low, less raw material is supplied, decreasing the molding pressure.

[0022] In this embodiment, the primary gate 12 and the secondary gate 13 are made of SUS304. General structural rolled steel (e.g., SS410) and martensitic stainless steel (e.g., SUS410) are prone to cracking due to wear, deformation, and brittle fracture, making it difficult to control the gate height as operation continues. Therefore, after extensive investigation, we found that equipment deterioration could be improved by using austenitic stainless steel (e.g., SUS304), which has both brittle resistance and wear resistance. [Example]

[0023] Example 1 In the present invention, the relationship between the height between the primary gate 12 and the double roll molding machine 6 and the width-direction deviation of the molding pressure was investigated. The results of investigating the relationship between the height between the primary gate 12 and the double roll molding machine 6 and the width-direction deviation of the molding pressure are shown in Figure 3. The test started with the primary gate 12 raised to its highest position, and the primary gate 12 was gradually lowered to investigate the width-direction deviation of the molding pressure. The molding pressure was evaluated by installing two load cells in the width direction.

[0024] The results in Figure 3 show that lowering the primary gate 12 suppresses the widthwise deviation of molding pressure, but that at a certain point, the widthwise deviation of molding pressure worsens. This is thought to be because the raw material layer thickness becomes thinner and the deviation increases due to insufficient supply. Furthermore, it was found that when the gate height of the primary gate 12 is 3 mm or less, clogging occurs frequently, making operation difficult. This is presumably due to the crushed particle size of the raw material (crushed to -3 mm). From the above, it was found that keeping the gate height of the primary gate 12 between 20 and 60 mm is optimal for suppressing the widthwise deviation of molding pressure.

[0025] <Example 2> In the present invention, the relationship between the widthwise deviation of molding pressure and molding yield was investigated. The results of the investigation into the relationship between the widthwise deviation of molding pressure and molding yield are shown in Figure 4. Here, the molding pressure (1.8 t / cm, 2.2 t / cm, 2.6 t / cm) was adjusted by controlling the height of the secondary gate 13. The molding pressure is the average pressure at two points in the width direction. From the results in Figure 4, it was confirmed that the yield improved as the deviation was suppressed, and furthermore, the molding pressure also reached an optimal value. From the above, it was found that it is desirable to control the molding pressure to 2.2 t / cm or more, preferably in the range of 2.2 t / cm to 2.6 t / cm. It was also found that it is desirable to suppress the widthwise deviation of molding pressure to 0.3 t / cm or less. [Industrial Applicability]

[0026] According to the present invention, by providing a double-roll molding machine with gates for controlling the layer thickness of the molding material and the molding pressure, it is possible to optimize the widthwise deviation of the molding pressure and the molding pressure, improve the molding yield of the molded product, and perform efficient molding. As a result, raw material is not wasted and manufacturing costs can be reduced. [Explanation of symbols]

[0027] 1. Coal 2. Iron ore 3. Mixing machine 4 binder tank 5. Conveying equipment 6 Double roll molding machine 6-1 Transport roll 6-2 Fixed roll 7 Sieve top 8 Under the sieve 9. Dry distillation furnace 11 Raw material hopper 12 Primary Gate 13 Secondary Gate K Kiss Club

Claims

1. 1. A process for producing ferro coke by kneading a molding raw material containing coal, an iron source raw material, and a binder, and carbonizing the resulting agglomerates in a double roll molding machine, the process comprising: passing the mixed molding raw material between a primary gate installed above one of the rolls of the double roll molding machine so as to be able to rise and fall, and the roll; passing the mixed molding raw material between a secondary gate installed above a kissing portion between the one roll and the other roll of the double roll molding machine so as to be able to rise and fall, and supplying the mixed molding raw material to the double roll molding machine; and molding the mixed molding raw material in the double roll molding machine to produce a molding.

2. 2. The method for producing a ferro-coke raw material according to claim 1, wherein a distance between the primary gate and one of the roll surfaces of the double roll molding machine is set to 20 to 60 mm.

3. 3. The method for producing a ferro-coke raw material according to claim 2, wherein the molding pressure of the double-roll molding machine is set to 2.2 to 2.6 t / cm, and the deviation of the molding pressure in the width direction of the double-roll molding machine is set to 0.3 t / cm or less.

4. 4. The method for producing a ferro-coke raw material according to claim 1, wherein the primary gate and the secondary gate are made of austenitic stainless steel.

5. 1. An apparatus for producing a ferro-coke raw material, which kneads raw materials for molding, including coal, an iron source material, and a binder, and obtains molded products by agglomerating the raw materials in a double-roll molding machine, the apparatus comprising: a primary gate installed so as to be raised and lowered above one roll of the double-roll molding machine; and a secondary gate installed so as to be raised and lowered above a kiss portion between the one roll and the other roll of the double-roll molding machine.

Images