KR20010016797A - Apparatus for charging sinter-mix onto pallet - Google Patents

Abstract

PURPOSE: An apparatus for charging sintering material is provided to make surface change of material charged into sintering truck stable and to increase vertical segregation level of material by optimizing horizontal motion elements of material after the motion condition of particles is enlarged in an upper portion of a chute. CONSTITUTION: An apparatus for charging sintering material includes a material supplying part and a chute (100). The material supplying part has a sintering material hopper (2) storing sintering material and a drum type feeder (3) for supplying the sintering material to the lower part. The chute charges the supplied sintering material to a sintering truck. The chute has an upper slant plate (110) and at least one or more lower slant plates (120,130,140). The upper slant plate is disposed slantingly near to the drum type feeder. The lower slant plate is disposed along a material charging direction while an inclined angle of each plate is gradually reduced at the lower part of the upper plate.

Description

Apparatus for charging sinter-mix onto pallet

The present invention relates to an apparatus for charging a sintered raw material into a sintering apparatus using a chute. More specifically, the upper part of the chute increases the state of movement of the particles, and thereafter, optimizes the horizontal motion of the raw material and loads it into the sintering bogie. The present invention relates to a sintered raw material charging device capable of increasing the vertical segregation of the raw material while maintaining a stable surface change of the raw material.

In general, in the sinter plant, the sintered raw materials are charged into the sintering trolley of the sintering machine using a charging device to manufacture the sintered ore. Figure 1 shows the most advanced type of sintered raw material charging device in recent years, which uses a slit wire chute 10.

In the sintering raw material charging device of FIG. 1, a sintering raw material hopper (2) in which a sintering raw material (1) containing fine powders such as fine iron ore and limestone and fine powder coke is stored, and the sintering raw material is rotated by rotating the sintered raw material hopper It is composed of a raw material supply section consisting of a dream feeder (3) for supplying the lower portion through the gate (4), and a chute (10) for charging the sintered raw material to the top of the bottom light first laid on the sintering cart (8) . The chute 10 includes an upper inclined plate 11, a slit wire 16, and a lower inclined plate 12, wherein the slit wire 16 and the lower inclined plate 12 have small particles on the upper portion of the sintered trolley 8 and a lower portion thereof. It serves to classify the sintered raw material so that large particles are charged (vertical segregation).

When the sintering raw material 1 is charged into the sintering bogie 8, the surface of the sintering raw material is evenly made by the surface of the flat plate 6, and then ignited in the ignition furnace 7 and sucked downward in the wind by the suction blower (not shown). The sintering reaction is performed by combustion of coke contained in the sintered raw material by air to produce a sintered ore.

In such a sintering operation, it is necessary to artificially encourage the coke, which is a fuel, to have a large amount of coke as fuel at the upper part so that the charged state of the raw material in the sintered trolley is placed at the lower part and the small particle at the upper part (vertical segregation bath). When the vertical segregation is effectively promoted, the calorific imbalance in the up-down direction of the sintering machine is suppressed, while the productivity (sintering resistance) of the air flowing into the raw material layer in the sintering machine is lowered to improve the sintered ore productivity. In this case, it is well known that it is best to keep the loading density of the raw material evenly in the width direction of the sintering machine if possible.

Therefore, in the field of sintered ore manufacturing, a lot of efforts have been made to improve the charging state of raw materials, which can be said to mainly depend on the improvement of the sintering raw material charging device.

Various types of chutes are shown in FIG. 2, and it is well known that in order to reinforce the vertical segregation of raw particles in the sintering machine, it is better to accelerate the horizontal velocity component (Vx) of falling particles regardless of the chute structure. to be. In particular, it is a good idea to lower the inclination angle α of the chute. However, in such a state, the loading speed of particles on the chute surface is slowed, so that stagnation is likely to occur. Is generated. When adhesion light is generated on the top surface of the inclined plate or the slit wire, the continuous flow of the raw material is disturbed, which causes the change of the loading density of the raw material in the width direction of the sintering bogie and is the biggest cause of irregular reaction state in the sintering machine. . Therefore, prevention of adhesion light along with vertical segregation is an important requirement for stable operation.

Even in the case of the slit wire chute as shown in FIG. 1, which is the most improved type recently, the inclination angle of the upper and lower inclination plates of the chute is in the range of 50 to 60 degrees due to the problem of adhesion of sintered raw materials. In the same way, it prevents adhesion light generation and promotes the vertical segregation. However, since the inclination of the upper inclined plate 11 is small, the direction of movement of the particles supplied from the drum-type feeder 3 is reversed, resulting in severe stagnation of the particles. Therefore, there is a problem that the occurrence of adhesion light on the upper inclined plate 11 is poor, and the movement state of the particles is also poor, so that the particle size classification is difficult before the particles reach the lower inclined plate 12 and the slit wire 16. In addition, the lower inclination plate also has a large inclination angle, so that the horizontal velocity component of the particles is reduced, and thus, vertical segregation of the sintered raw material is not effectively promoted in the sintered trolley. In addition, in particular, there is a problem in that adhesion light is easily formed on the surface of the slit wire provided on the front side of the raw material flow direction and the surface of the lower slant plate through which the fine powder flows. Adhesion of the sintered raw material becomes more severe as the moisture content of the raw material increases. In sintered raw materials, fine iron ore contains about 6% water.

In order to solve this problem, Japanese Laid-Open Patent Publication No. 9-210566 provides a charging device configured to install a plurality of wires in a slanted direction instead of an inclined plate-shaped chute, and to automatically remove the attachment light from the wire. It has been proposed. This method is structurally complex despite its many advantages, and is particularly difficult to apply, such as requiring a new control method for charge height control.

In JP-85543,88240 ('87), a plurality of rods are installed at the bottom of the inclined chute in the direction of flow of the raw material on the inclined plane, and each rod is rotated in a funnel with one end at the vertex. A charging device has been proposed to play a role similar to slit wire while injecting the raw material drop width. In principle, the advantages are great, but the equipment is structurally very complicated, and it is known that there are problems such as many problems in maintenance and stability caused by long-term operation.

As described above, the sintering raw material charging device proposed so far focuses on the dispersion function of the raw materials charged to the sintering machine, and thus cannot effectively solve the operation instability due to the irregularly occurring adhesion light during the operation process or the removal of the adhesion light. There was a problem that a complex type of device had to be installed. In addition, in the general charging device, periodic fluctuations in the loaded raw material surface, such as the accumulation of raw materials in the sintering machine and being settled by its own weight, are severe, which is known to be fatal to the vertical particle size segregation in the sintering machine.

The present invention has been proposed in order to solve the above-mentioned conventional problems. In the upper part of the chute, the motion state of the particles is increased, and the horizontal motion of the raw material is optimized thereafter, thereby optimizing the horizontal motion of the raw material. It is to provide a sintered raw material charging device that can increase the vertical segregation of the raw material while the surface change is stable.

1 is a schematic diagram of a sintered raw material charging device using a slit wire (or rod) chute

2 is a graph showing the effect of particle velocity on segregation

Figure 3 is an example of the sintering raw material charging device of the present invention

4 is a conceptual diagram showing the action of the chute of the present invention

5 is a basic structural diagram of the chute of the present invention

Figure 6 is a schematic diagram comparing the chute of the present invention and the conventional one-piece chute.

Figure 7 is a schematic diagram comparing the sintered raw material charging device of the present invention and the sintered raw material charging device employing a conventional one-piece chute.

8 is an example in which the adhering ore removing means is adopted in the sintering raw material charging device of the present invention.

Figure 9 is a schematic diagram showing the amount of deposit ore according to the inclination angle of the chute in the sintering raw material charging device of the present invention

10 is a graph showing the characteristics of the present invention and the conventional charging device

* Description of protection for the main parts of the drawing *

1 ..... Sintered raw material 2 ..... Hopper

3 ..... drum feeder 4 ..... gate

10, 100 ..... chute 11, 110 ..... (top)

12, 120, 130, 140 ..... lower slope

111, 121 ..... 2nd slope 112 ..... blade scraper

113 ..... Nozzle Scraper

The sintering raw material charging device of the present invention for achieving the above object, the raw material supply unit consisting of a sintering raw material hopper and a drum-type feeder for supplying the sintering raw material and the sintering raw material supplied In the sintered raw material charging device comprising a chute to charge, the chute

(a) a top inclined plate having an upper end inclined close to the drum feeder; and

(b) at least one lower inclined plate which is sequentially disposed along the raw material loading direction while the inclination angle of each plate gradually decreases from the lower portion of the upper inclined plate.

Hereinafter, the present invention will be described in detail.

In the sintering raw material charging device of the present invention, the upper part of the chute is mainly used to increase the state of movement of the particles, and the lower part of the inclined plate to separate the role of each part of the inclined plate so as to gradually increase the horizontal motion component of the raw material. There is a characteristic in constructing a chute.

In general, the sintering raw material charging device can (1) effectively classify the sintering raw materials on the inclined surface, (2) effectively promote vertical segregation in the sintering machine, and (3) reduce the loading density of the raw materials in the sintering machine. Most preferably, it is configured to be.

Therefore, it is important to design the sintered raw material charging device from the viewpoint of (1) (2) (3), of which (3) the loading density of raw materials in the sintering machine is generally secured by keeping the raw material drop width wide on the inclined surface. have. In the present invention, a sintered raw material charging device is constructed in terms of (1) particle classification and (2) vertical segregation.

(1) The particle classification of the sintered raw material can be effectively achieved by lengthening the length of the inclined surface to make the moving distance of the particles as long as possible, which facilitates stagnation of raw material flows or formation of adhesion light thereby. In this way, the particle classification of the sintered raw material and the generation of the adhering light have a mutually adverse relationship. Therefore, since the length of the inclined surface considering particle classification is currently optimized, how to effectively prevent the generation of adherent light is an important issue.

Therefore, in the present invention, the point where the adhesion is expected in the chute of the chute of the sintered raw material charging device is configured to preferentially play a role of maintaining the state of movement of the particles, and then gradually change the direction of movement of the flowing particles thereafter. As a result, the inclined plate is configured to structurally prevent the formation of the adhesion light due to the stagnation of the particles. This configuration can minimize the generation of adherent light, thereby maximizing the classification of particles.

(2) Vertical segregation can be encouraged by increasing the horizontal velocity component of the particle velocity at the bottom of the slope. Therefore, in the present invention, the angle of inclination of the inclined plate is gradually decreased to maximize the vertical segregation by gradually increasing the horizontal velocity component of the raw material particles.

As described above, the present invention has developed a sintered raw material charging device based on the kinetic principle of the sintered raw material, which will be described with reference to FIGS. 3 to 8.

Figure 3 shows a preferred example of the sintered raw material charging device of the present invention. The sintering raw material charging device of the present invention comprises a raw material supply unit and a chute 100 including a sintering raw material hopper 2 and a drum feeder 3.

In the present invention, the chute 100 is gradually inclined angle (horizontal angle, A) of each plate from the top inclined plate 110 and the bottom of the top inclined plate 110 is disposed inclined close to the drum feeder (3) It is configured to include one or more lower inclined plates (120, 130, 140) sequentially arranged along the raw material loading direction while being smaller.

In the present invention, in consideration of the distance (height) between the drum feeder (3) and the sintered trolley and the length of the inclined plate, a plurality of inclined plates are sequentially separated and arranged, and at this time, the inclination of the inclined plate gradually decreases downward.

By gradually decreasing the inclination angle of the inclined plate, the inclination angle of the upper part can be increased relatively and the inclination angle of the lower part can be made small. Therefore, since the motion state of the particles can be increased in the upper side, the particle size classification is smooth and the generation of adhesion light is reduced. In the lower side, the vertical segregation is increased because the horizontal velocity component of the sintered raw material particles is gradually increased.

In the present invention, the top inclined plate 110 inverts the movement direction of the raw material particles supplied from the drum feeder (3). Therefore, since the particles are likely to be congested in this part, the inclination angle is as high as possible only for the purpose of reversing the direction of movement of the particles and maintaining the flow of the particles on the inclined plane. Preferably, the top inclined plate 110 has an inclination angle of 90 to 60 degrees.

In the present invention, the lower inclined plate (s) has an inclined angle smaller than the inclined angle of the upper inclined plate at an inclination angle of 30 degrees or more so that the inclined angle gradually decreases. At this time, the inclination angle deviation between the inclined plates shall be within 20˚. If the inclination angle of the lower inclination plate is less than 30 °, there is a concern of generating the light, and even if the inclination angle deviation between the inclination plates becomes too large, there is a possibility that the attachment light is generated by causing particle retention on the inclined plane.

In the present invention, the chute may be composed of four inclined plates as shown in FIG. That is, three lower inclined plates (second, third, and fourth stage inclined plates) may be disposed from a lower portion of the uppermost (first stage) inclined plate to an upper portion of the sintered trolley. A second stage inclined plate having an inclination angle of 50 to 70 degrees, a third stage inclined plate having an inclination angle of 40 to 60 degrees, and a fourth stage inclined plate having an inclination angle of 30 to 50 degrees may be sequentially disposed.

In addition, in the present invention, as shown in FIG. 4, the upper end of the lower inclined plate 120 is positioned directly below one end of the lower surface of the upper inclined plate 110 such that the inclined plate is disposed such that a step is formed. This allows the upper and lower inclined plates to be spatially separated, so that the flow of small particles can be effectively maintained.

The operation of the chute of the present invention will be described in detail with reference to FIG.

The top inclined plate (also referred to as 'first stage inclined plate') is maintained in a substantially vertical state, and thus the raw material supplied from the drum feeder 3 flows in the direction of the inclined surface without congestion by minimizing the inversion phenomenon (a). The raw material particles (b) are fed to the second inclined surface below the raw material particles (b) while the vertical motion component becomes very large to maintain the flow state of the particles.

The space between the first and second slope plates is spatially separated to effectively maintain the flow of small particles flowing on the surface of the inclined surface (c), and the main flow of the raw material flowing through the inclined surface (b) remains the same as the flow direction thereof. maintain.

The second stage inclined plate serves to gradually change the flow direction (b) of the raw material particles having a large vertical motion component supplied from the first stage inclined plate to the horizontal direction. In this case, too, the sharp angular deviation of the second and third inclined plates may cause particle congestion on the inclined surface, thereby easily generating adhesion light, and thus, an appropriate angle change is required under conditions that maintain the flow of particles. Here, the second and third stepped slant plates are used to gradually change the movement of the particles flowing in the vertical direction mainly in the first stepped slanted plate to the horizontal direction. It plays an intermediate role in eliminating particle flow congestion.

Finally, the fourth step sloping plate performs the goal of maximizing the horizontal speed of the raw material supplied to the sintering bogie, and gradually reduces the inclination angle of the first, second and third step sloping plates to the final target angle of 50 to 30. By lowering to a degree, the particle motion b in a substantially vertical flow state in the first stage is changed to a particle motion having a large horizontal velocity component as in i.

In the conventional charging device, since the inclination angle of the inclination plate is configured to be maintained the same, the inclination angle has to be increased to prevent the formation of adhesion light. Accordingly, it was difficult to reinforce the vertical segregation of particles in the sintering machine bogie. On the contrary, since the device of the present invention is arranged with a slanted plate to increase the horizontal velocity of the particles, it is possible to induce vertical segregation of the particles in the sintering machine and to actively prevent generation of adherent light due to stagnation.

5 and 6 illustrate the advantages of the sintered raw material charging device of the present invention.

In FIG. 5, when the height of the inclined plate is H and the inclination angles of the first, second, third, and fourth stepped plates are 75 °, 65 °, 55 °, and 45 °, respectively, the total lengths of the inclined surfaces of the four inclined plates are [( 1.035 + 1, 103 + 1, 221 + 1.414) / 4 × H], which is 1.93 times the height of the inclined plate. The width W is 0.609 times the height.

Here, as shown in FIG. 6, the length of the inclined surface is longer than that of the 1.155 × H, which is the length of the OA inclined surface which is integrally maintained at the device width of the invention, which indicates that the possibility of date classification on the inclined surface can be increased. Compared to the case of the inclined surface of the OB unit, which is configured at the same angle as the fourth inclined plate under the condition that there is no congestion, the width of the invention device is 0.609 times smaller, which is advantageous in that the device can be easily applied even in a narrower space.

On the other hand, Figure 7 shows a comparison of the application state of the device of the invention and the conventional inclined plate-type charging device under the same equipment conditions. Where P is the inclined plate impact point of the raw material supplied from the drum-type feeder (3), H is the height from the collision point to the top of the sintering machine bogie, L means the height from the collision point to the end of the inclined plate.

The falling distance D from Fig. 7 (a) (b) (c) showing the integrated inclined plate type device in Fig. 7 is longer and sintered as the inclination decreases due to the interference of peripheral devices such as the drum feeder 3. Since the height to the plane becomes short, the energy loss rate due to the collision on the inclined surface becomes large, and the horizontal velocity distribution ratio of the falling particle velocity, that is, the COS (A), becomes large.

Here, the conversion of the potential energy of the feedstock particles into kinetic energy is advantageous as the inclination angle of the inclined surface is larger, and the inclination angle of the conversion of the potential energy of falling particles into kinetic energy is greater. However, it can be seen that the velocity distribution in the horizontal direction of the falling particles has an advantageous opposite relationship as the inclination angle is smaller.

In the sintered raw material charging device of the present invention, as shown in FIG. 7 (d), the inclination angle of the inclined plate gradually decreases toward the bottom to solve the two opposite elements by structurally burdening the function. In other words, by dividing the inclined plate into pieces to increase the angle of the upper inclined plate to reduce the collision energy loss rate of the feedstock particles, while preventing the stagnation of the raw material particles on the inclined surface, and gradually reducing the inclination angle of the pieces of several pieces below the raw material particles By converting the potential energy into kinetic energy, the ratio of the horizontal velocity component of the particle is increased.

In the present invention, it is possible to configure a structure in which each inclined plate is inserted into the entire steel structure in the form of a cassette, and accordingly there is a feature that is extremely easy to manufacture or modify. In addition, the chute adopts a means for adjusting the inclination angle of the inclined surface can be adjusted as needed.

In addition, in the sintering raw material charging device of the present invention, a scraper that can prevent the adhesion of the adhesion light in advance or remove the adhesion light in case of occurrence of adhesion light may be employed, and an example thereof is shown in FIG. 8. have.

8 (a) shows an example of additionally removing or preventing the attachment light by further installing a second inclined surface 111 on each inclined surface 110 as necessary. That is, the second inclined surface may move up and down on the inclined plate to remove the ore attached to the inclined surface.

In FIG. 8B, a blade type remover 112 may be additionally installed on each inclined surface 110 as necessary to prevent or remove generation of adhesion light. The blade type eliminator is configured to be in contact with the inclined surface to reciprocate left and right along the inclined surface to remove the attachment light.

In FIG. 8C, for example, an air spray nozzle 123 is installed between the first and second inclined plates 110 and 120 to inject air in the longitudinal direction of the inclined plate. It is configured to remove the ore to be attached.

Hereinafter, the present invention will be described in detail through examples.

Example 1

In order to realize the apparatus of the present invention, as shown in FIG. 9, the inclination plate chute (material: SUS304) was installed in such a manner that the inclination angles of 1 to 4 inclinations were adjusted by 1 to 4 on the basis of the overall height. In the experiment of this device, Australian hematite was adjusted to 6% moisture and used as a raw material. Particularly, the identity of the particles was determined based on the static state of the particles on the inclined surface in the stationary state after maintaining the uniform charging state for 1 minute.

9 (a) shows the identity of the particles on the inclined surface when the sintered raw material is charged using a chute employing only one inclined plate, the inclined angle of the inclined plate is in the range of 80 to 60 degrees. In this case, since the supply direction of the particles and the inclination direction of the inclined plate are different, the stagnation of the particles due to the direction change of the particles is severe, and especially the tendency is apparent at 60 ° or less.

FIG. 9 (b) shows the inclination angle of the second inclined plate when the top inclined plate (first stage inclined plate) is inclined angle of the second stage inclined plate in the range of 60-50 degrees under the condition of inclined angle of 70 degrees. It shows the identity of particles on the surface.

In FIG. 9 (c), when the uppermost inclined plate (first stage inclined plate) and the lower second to third inclined plates are arranged, the first inclined plate: 70 degrees, the second stage inclined plate: 60 degrees, and the third stage inclined plate: When the inclination angle is set to 40 to 60 degrees, the identity of particles on the surface is shown according to the inclination angle of the third inclined plate.

In FIG. 9 (d), when the uppermost inclined plate (first stage inclined plate) and the lower second to fourth inclined plates are arranged, the first stage inclined plate: 70 degrees, the second stage inclined plate: 60 degrees, and the third stage inclined plate: 50 °, fourth step inclination plate: When the inclination angle is set to 30 to 50 °, the identity of the particles according to the inclination angle on the surface of the fourth step inclination plate is shown.

In FIG. 9 (b) (c) (d), since the supply direction of the particles is similar to the inclination direction of each inclined plate, it is possible to change the state of movement of the particles without significant particle retention within the range of about 20 °. .

Example 2

As shown in FIG. 10, in the case of the integrated inclined plate of various types similar to the apparatus of the present invention, the inclined plate ends are maintained for the case where the raw material drop position is kept the same and the feed rate of the raw material is changed to 50-300 (Ton / Hr / m). The variation of segregation degree was shown by the change of the velocity ratio (Vx / Vy) of the falling particles at, and the change of the inclination angle of the loading surface of the raw material accumulated in the sintering machine.

Segregation degree (-) = (lowest layer average particle size-uppermost layer average particle size) / (lowest layer height-lowest layer height)

In the case of the integrated chute with an angle of 75 °, the dropping speed of particles was the fastest, but the velocity ratio (Vx / Vy) was small, and the loading surface angle was very large, but the variation was narrow. Fewer results. As the inclination angle decreases (B → D), the velocity ratio of the particles increases, and the variation of the charge surface angle increases slightly, but segregation tends to increase. On the contrary, in the case of the apparatus of the present invention (A), the speed ratio is the largest, the change width of the charging surface is relatively stable, and the segregation degree is greatly improved.

According to the experimental results, the device of the present invention has the largest ratio of the velocity of falling particles even in the structure of the same height and narrower width, and the change of the loading curve is relatively stable. It was concluded that it could increase dramatically. As such, when the vertical segregation is increased, sintered ore productivity is improved by reducing the air flow resistance for combustion flowing into the sintering machine, while preventing the unevenness of calories in the upper and lower portions of the sintered layer, thereby effectively improving the sintered ore recovery rate.

In the embodiment of the present invention, the charging device of the present invention has been described using four inclined plates as an example, but the present invention is not limited thereto. In the present invention, the inclination angle of the inclined plate is gradually reduced to increase the horizontal velocity component of the falling particles, and the same has the same effect as the technical idea of promoting vertical segregation. Included.

For example, in this invention, the case where a 1st step inclination plate and a 2nd step inclination plate have the same inclination angle, and the inclination angle of a 3rd step inclination plate and a 4th step inclination plate is also considered to become small gradually. This should be regarded as the case where the first stage inclined plate and the second stage inclined plate are one inclined plate.

As described above, the sintered raw material charging device of the present invention is very simple in structure, but the optimum state of motion of the raw material can be optimized to effectively promote vertical segregation of particles in the sintering machine, and in particular, has the advantage of preventing the generation of adhesion light. Have In addition, since the inclined plates are arranged in sequence according to the raw material loading direction, each inclined plate is separated and installed, and thus the maintenance of the inclined plate is extremely easy as well as the removal of the attachment light generated on the inclined surface. In particular, in the conventional sintered raw material charging device, the advantage of utilization is also great, such that the device of the present invention can be applied by utilizing only a narrow space without a large change in equipment.

Claims (4)

In the sintering raw material charging device comprising a raw material supply unit consisting of a sintering raw material hopper which stores the sintering raw material and a drum feeder for supplying the sintering raw material and a chute for charging the sintering raw material to the sintering truck, The suit (a) a top inclined plate having an upper end inclined close to the drum feeder; and (b) Sintering raw material charging device characterized in that it comprises at least one lower inclined plate sequentially disposed along the raw material loading direction while the inclination angle of each plate in the lower portion of the top inclined plate gradually decreases. The inclination angle of the uppermost inclination plate is in the range of 90 to 60 degrees, the lower inclination plate (s) is less than the inclination angle of the upper inclination plate and has an inclination angle of 30 degrees or more, and the inclination angle deviation between the inclination plates is 20 Sintered raw material charging device characterized in that it is within ˚. The second stage inclined plate having an inclination angle of 50 to 70 degrees from the lower portion of the uppermost (first stage) inclined plate to the upper portion of the sintered trolley, and the third stage inclined plate having an inclination angle of 40 to 60 degrees. Sintered raw material charging apparatus, characterized in that the fourth stage inclined plate having an inclination angle of 30-50 ° are sequentially arranged. The sintered raw material according to any one of claims 1, 2, and 3, wherein the upper and lower inclined plates are disposed such that an upper end portion of the lower inclined plate is directly below one end of a lower surface of the upper inclined plate so that the inclined plate is formed with a step. Charging device.