Apparatus for producing raw materials for blast furnaces and method for producing raw materials for blast furnaces

Abstract

To provide a method and an apparatus for manufacturing a formed coke which reduces an amount of powder flowing into a dry distillation furnace, and thereby dissolves uneven distribution of the powder in the dry distillation furnace at the time of manufacture of a formed coke such as a ferro coke, and has high quality and high productivity.SOLUTION: An apparatus for manufacturing a raw material for a blast furnace includes a dry distillation furnace 6 for distilling a carbon-containing substance and manufacturing a formed coke, and a charging chute 1 for supplying the carbon-containing substance from outside, where the charging chute has an inclined part, and has a sieve 2b provided at least a part on a lower surface side of the inclined part of the charging chute, and means for separating or collecting a sieve which passes through the sieve and has a small diameter out of the carbon-containing substance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for producing raw material for a blast furnace. [Background technology]

[0002] In recent years, the steel industry has been required to reduce CO2 gas emissions in order to prevent global warming, and there is an urgent need to reduce the use of fossil fuels. In the steel industry, molten iron is produced in blast furnaces by reducing iron ore with carbon (coke produced by carbonizing coal in a coke oven). To reduce the coke consumption, technology is being developed to use molded coke, especially ferrocoke, as a raw material for blast furnaces. Ferrocoke is made by mixing a certain amount of iron ore with coal and forming it into agglomerates, then carbonizing it to disperse fine metallic iron particles in the coke. The catalytic action of the dispersed metallic iron increases the reactivity of the coke.

[0003] As a method for carbonizing ferro-coke, a method using a vertical carbonization furnace has been proposed, and for example, Patent Document 1 discloses a method for producing ferro-coke using a vertical carbonization furnace having a carbonization zone at the top and a cooling zone at the bottom. This method includes a charging step of charging molded materials made of carbon-containing materials and iron-containing materials into the carbonization furnace using a molded material charging device (hereinafter referred to as a charging chute), a carbonization step of carbonizing the molded materials in the carbonization zone by injecting heated gas to produce ferro-coke, a cooling step of cooling the ferro-coke by injecting cooling gas, an in-furnace gas discharge step of discharging in-furnace gas from an outlet at the top of the carbonization furnace, and a ferro-coke discharge step of discharging the ferro-coke from the bottom of the cooling zone. In the carbonization step, the molded materials are heated by injecting low-temperature gas from a low-temperature gas inlet in the middle of the carbonization zone and high-temperature gas from a high-temperature gas inlet in the bottom of the carbonization zone into the furnace. In the cooling process, the ferro-coke is cooled by blowing in cooling gas from the cooling gas blowing tuyeres at the bottom of the cooling zone. Here, in order to increase the production volume of ferro-coke, it is necessary to increase the volume of the carbonization furnace, but in order to allow the heating gas and cooling gas to penetrate to the center of the carbonization furnace, it is necessary to keep the internal dimensions of the furnace in the depth direction (parallel to the horizontal component of the direction in which the molded materials are charged) below a certain level. Therefore, the carbonization furnace has a shape that is longer in the furnace width direction (perpendicular to the depth direction in the cross section of the carbonization furnace) than in the depth direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-57970 A [Patent Document 2] JP 2011-162271 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a vertical carbonization furnace with a structure in which the furnace width direction is longer than the furnace depth direction as described above, it is difficult to obtain a uniform charging distribution even if multiple rows of briquette charging inlets are arranged in the furnace width direction. In particular, powder generated by the collision of the briquette with the charging chute wall or between the briquette is likely to segregate inside the furnace body of the carbonization furnace and tend to be concentrated near the charging inlet. This is because most of the powder in the charging material slips through the briquette and settles, and the charging material is separated into two layers, a briquette layer (upper layer) and a powder layer (lower layer), before reaching the furnace body of the carbonization furnace. If 1 ton of briquette is supplied to the charging chute, the thickness of the charging material when it enters the carbonization furnace will be a maximum of about 150 mm, and the briquette particles in the upper layer will tend to fly to a position away from the charging inlet, while the powder in the lower layer will tend to fall near the charging inlet. The compacts form mountains according to their angle of repose, resulting in a relatively uniform distribution, but the powder is fixed in position by sinking between the compacts, so if the powder falls concentrated at one point, significant segregation will occur. One problem caused by powder segregation is that it causes uneven gas flow in the furnace, which affects the carbonization of the compacts.

[0006] As a method for uniformly charging materials, Patent Document 2 discloses a method for radially dispersing materials by providing a dispersion guide section with an inclined surface that slopes radially downward from the widthwise center of the conveying path toward the outlet side, but this technology is specialized for improving dispersion in the furnace width direction. The presence or absence of a dispersion guide section does not affect the flying distance of powder, and the installation of a dispersion guide section cannot eliminate powder segregation at the charging inlet side.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to propose a method and apparatus for producing high-quality, highly productive molded coke by reducing the amount of powder flowing into the furnace body of the carbonization furnace, thereby eliminating the uneven distribution of powder in the carbonization furnace when producing molded coke such as ferro coke. [Means for solving the problem]

[0008] The means for solving the above problems are as follows. [1] A blast furnace raw material manufacturing apparatus comprising a carbonization furnace for producing molded coke by carbonizing a carbon-containing material, and a charging chute for supplying the carbon-containing material from an outside, The charging chute has a sloped portion, A sieve is provided on at least a portion of the lower surface side of the inclined portion of the charging chute, 4. The apparatus for producing raw material for a blast furnace, comprising: a means for separating or recovering small-sized particles of the carbon-containing material that have passed through the sieve. [2] The blast furnace raw material manufacturing apparatus described in [1], characterized in that the charging chute has a branched portion, and a part of the branched portion is one of the inclined portions having a sieve. [3] A raw material manufacturing apparatus for a blast furnace as described in [1] or [2], characterized in that a portion of the charging chute near the connection with the carbonization furnace is one of the inclined portions having a sieve. [4] The apparatus for producing raw materials for a blast furnace according to any one of [1] to [3], characterized in that a sieve provided in the charging chute is a grizzly sieve. [5] The apparatus for manufacturing raw materials for a blast furnace described in [2], characterized in that the sieve provided at the branching portion of the charging chute is a grizzly, and the rods constituting the grizzly are arranged so as to be parallel to the direction in which the carbon-containing material moves within the charging chute. [6] A raw material manufacturing apparatus for a blast furnace as described in [3], characterized in that it has a gate for temporarily retaining carbon-containing materials near the connection portion of the charging chute with the carbonization furnace, a sieve provided near the connection portion of the charging chute with the carbonization furnace is a grizzly, and the rods constituting the grizzly are arranged so as to be perpendicular to the direction in which the carbon-containing materials move within the charging chute. [7] A method for producing raw material for a blast furnace, comprising producing raw material for a blast furnace using the apparatus for producing raw material for a blast furnace according to any one of [1] to [6]. Effect of the Invention

[0009] According to the present invention, the quality of molded coke to be charged into a blast furnace is improved and the productivity is increased. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are a front view and a side view, respectively, of a facility according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of the present invention will be described below by taking as an example a manufacturing process of ferro-coke, a type of molded coke that is a raw material for a blast furnace. Note that the drawings are schematic and may differ from the actual product. Furthermore, the following embodiment is an example of an apparatus for manufacturing raw materials for a blast furnace and a method for manufacturing raw materials for a blast furnace to embody the technical idea of ​​the present invention, and is not intended to specify the configuration as described below. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0012] FIG. 1 is a front view and a side view of a carbonization furnace and a charging chute, which are ferro-coke manufacturing equipment in the present invention. The carbonization furnace has a shape in which the furnace width direction (perpendicular to the depth direction in the cross section of the carbonization furnace) is longer than the depth direction, which is the charging direction of the raw materials, and the side viewed from the side in the furnace width direction is referred to as the front in the following description. First, briquettes consisting of carbon-containing materials (coal, etc.) and iron-containing materials (iron ore, etc.) that are raw materials for ferro-coke are supplied from the outside to the charging chute 1. When the briquettes are supplied, the gate 5 provided near the connection part of the charging chute with the carbonization furnace is in a closed state, and one batch of briquettes is piled up upstream of the gate 5. Next, the gate 5 is opened, and the briquettes are charged into the inside of the furnace body 6 of the carbonization furnace installed at a lower position than the charging chute. At this time, the briquettes pass through the diffusion part 4 that promotes dispersion in the furnace width direction and fall into the carbonization furnace. The diffusion part has a structure in which the length in the furnace width direction is longer than the charging chute.

[0013] In the present invention, in order to eliminate uneven distribution of powder in the carbonization furnace, a sieve is provided on a part of the inclined part of the charging chute, and a means is provided for separating only small-diameter particles (hereinafter also referred to as small-diameter powder and powder) from the charging material when the charging material passes along the inclined part and recovering them below the sieve. Here, small-diameter powder among the charging material refers to particles whose particle diameter is two-thirds or less of the average particle diameter of the molded product. As described above, since the powder in the charging material settles through the gaps in the molded product while moving through the charging chute, and since the powder is generated not only at the inlet side of the charging chute but also near the outlet of the charging chute, in order to increase the powder recovery rate, it is desirable that the inclined part where the sieve is installed is a part near the connection part of the charging chute with the carbonization furnace. Specifically, the lower surface side 2b of the upstream part of the gate 5 near the connection part of the charging chute with the carbonization furnace is preferable, and the distance between the gate 5 and the sieve is preferably 0.5 m or less. In addition, when the charging chute branches into two or more branches on the way, the lower surface side 2a of the branching part is also preferable as a sieve installation location. As mentioned above, the powder in the charging material settles through the gaps in the molded products, but the degree of settling depends on the amount of charging material (thickness of the charging material layer). The larger the amount of charging material (thicker the layer), the longer the distance that the powder particles originally in the upper layer have to travel before reaching the bottom layer, making it more difficult for them to settle. Therefore, in order to efficiently separate and recover powder with a sieve, it is important to suppress the supply speed of the charging material passing over the sieve and to allow as much powder as possible to settle to the bottom layer. The branching part is an inclined surface with a certain length, and is preferable because the charging material passes through it continuously or intermittently at a small flow rate without stagnation. In addition, it is preferable to use a grizzly type sieve because it is possible to efficiently recover powder while suppressing clogging. Here, the grizzly type sieve refers to a sieve with a shape in which rods are lined up in one direction. The recovered powder 7 may be molded again and then fed to the charging chute again.

[0014] The bars constituting the grizzly are preferably arranged so that they are parallel to the direction in which the charge moves along the inclined section on the underside 2a of the branch section, and perpendicular to the direction in which the charge moves along the inclined section on the underside 2b of the upstream section of the charging chute exit gate. As mentioned above, the charge is temporarily retained on the grizzly on the underside of the upstream section of the gate close to the charging chute exit, so that the powder in the charge that has settled through the gaps in the molded material while passing through the charging chute can be recovered. Next, after the gate 5 is opened, a large amount of charge particles pass over the grizzly in a short time. Immediately after the gate 5 is opened, the molded material is clogged between the bars (holes) of the grizzly, so the powder recovery rate is low, and the molded material that has been retained on the grizzly flows down into the furnace body 6 of the carbonization furnace, and as the number of particles present on the grizzly decreases, the powder recovery rate increases. Here, if the rods constituting the grizzly are arranged parallel to the flow direction of the charge material, the molded material that had been retained immediately after the gate is opened slides down along the hole while blocking the hole, so that the grizzly is almost entirely blocked, and the powder recovery rate temporarily drops to 0%. On the other hand, if the rods are arranged perpendicular to the flow direction of the charge material, the molded material that flows down on the grizzly cannot move along the hole of the grizzly, and it will proceed by repeating the falling motion into the hole and the motion of overcoming the step formed by the rods. In other words, the molded material will draw a trajectory that looks like it is vibrating, and a gap will be created between the molded material and the grizzly. Therefore, it is possible to recover the powder immediately after the gate 5 is opened, and the final powder recovery rate will increase significantly. Note that, if the rods are arranged perpendicular to the flow direction of the charge material, the molded material will remain on the grizzly even after the charging into the carbonization furnace is completed, but this residual amount does not have a negative effect on the powder recovery rate. As described above, a large amount of burden particles pass through the grizzly near the outlet of the charging chute in a short period of time, so there is strong mutual interference between the burden particles, and most of the molded material remaining on the grizzly is washed away by newly supplied burden particles.

[0015] On the other hand, when the Grizzly is installed at the branch of the charging chute, the charged molded materials are appropriately sorted by the sorting damper 3, and the molded materials slide down without stagnation. In this case, since the mutual interference between the particles of the charge material is weak, it is not easy to push away the molded materials that have once stagnated on the Grizzly. Even if the molded materials slide down along the holes, they do not block the entire Grizzly. In addition, if the bar is made perpendicular to the flow direction of the charge material, part of the charge material collides with the side of the bar and jumps up, that is, the contact time between the Grizzly and the charge material is shortened, and the powder recovery rate decreases by a few percent, so there is no advantage to making the Grizzly perpendicular to the flow direction of the charge material at the branch where the charge material does not stagnate.

[0016] The above-mentioned device and method can reduce the amount of powder flowing into the furnace body of the carbonization furnace. This can eliminate uneven distribution of powder inside the carbonization furnace during the production of molded coke, improving the ventilation inside the furnace body. In other words, the quality of the carbonization product is stabilized because carbonization defects caused by insufficient supply of carbonization gas to the powder uneven distribution area are less likely to occur, and problems that may affect operation, such as the carbonization product being discharged at a high temperature due to insufficient supply of cooling gas at the bottom of the furnace, causing a fire, can be prevented in advance, and a manufacturing device and manufacturing method for molded coke with high quality and productivity can be realized. EXAMPLES

[0017] The powder recovery rate was investigated when the molded and powdered materials were charged using a test device simulating the ferro-coke manufacturing device shown in Figure 1. The charging amount was 250 kg, and the initial powder rate was 8% by weight. Here, the oversieve (diameter 20 mm or more) with a sieve mesh of 20 mm was considered to be molded materials, and the undersieve (diameter less than 20 mm) was considered to be powder. Recovery boxes were installed just below the grizzly and at the outlet of the charging chute, and the powder weight in each recovery box was measured. The ratio of the powder weight in each recovery box just below the grizzly to the total powder weight in all recovery boxes was calculated and used as the "powder recovery rate." Considering that the molded diameter was about 30 mm, the interval between the grizzly rods (the distance between the end faces of the rods) was set to 25 mm. The rods were rectangular, and the width of the faces parallel to the flow direction of the charging materials was set to 10 mm. [Example 1] The effect of installing Grizzly at the branching section of the charging chute was investigated. The results are shown in Table 1. Grizzly was installed only at the branching section, and was not installed near the outlet of the charging chute (upstream side of the gate). Table 1 shows that by arranging the bars that make up the Grizzly so that they are parallel to the direction in which the charging material moves along the inclined section (flow direction), it is possible to recover about half of the powder without causing clogging.

[0018] [Table 1]

[0019] [Example 2] The effect of installing a Grizzly near the outlet of the charging chute (upstream side of the gate) was investigated. The results are shown in Table 2. Grizzly was only installed near the outlet of the charging chute, and no Grizzly was installed at the branching section. Table 2 shows that by arranging the rods that make up the Grizzly so that they are perpendicular to the direction in which the charging material moves along the inclined section (flow direction), it is possible to recover approximately 70% of the powder. In addition, although some molded material was found to remain on the Grizzly, the powder recovery rate did not decrease even with repeated charging, which shows that the molded material remaining on the Grizzly does not have a negative effect on the powder recovery rate.

[0020] [Table 2] [Explanation of symbols]

[0021] 1: Charging chute 2a: Sieve (Grizzly) on the underside of the branch 2b: Sieve on the lower side near the outlet of the charging chute (Grizzly) 3: Distributing damper 4: Diffusion section 5: Gate 6: Furnace body of carbonization furnace 7: Recovered powder

Claims

1. A blast furnace raw material manufacturing apparatus comprising a carbonization furnace for producing molded coke by carbonizing a carbon-containing material, and a charging chute for supplying the carbon-containing material from an outside, The charging chute has a sloped portion, A sieve is provided on at least a portion of the lower surface side of the inclined portion of the charging chute, The charging chute has a branched portion, and a part of the branched portion is one of the inclined portions having a sieve, 4. The apparatus for producing raw material for a blast furnace, comprising: a means for separating or recovering small-sized particles of the carbon-containing material that have passed through the sieve.

2. 2. The apparatus for producing raw materials for a blast furnace according to claim 1, characterized in that a part of the charging chute near the connection with the carbonization furnace is one of the inclined parts having a sieve.

3. 3. The apparatus for producing raw material for a blast furnace according to claim 1, wherein a sieve provided in the charging chute is a grizzly sieve.

4. The blast furnace raw material manufacturing apparatus according to claim 1, characterized in that the sieve provided at the branching portion of the charging chute is a grizzly, and the rods constituting the grizzly are arranged so as to be parallel to the direction in which the carbon-containing material moves within the charging chute.

5. A method for producing raw material for a blast furnace, comprising producing raw material for a blast furnace using the apparatus for producing raw material for a blast furnace according to any one of claims 1 to 4.

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