JPH1150120A - Maintainance of rotary furnace hearth in production of reduced iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maintaining method of a hearth furnace which can keep the surface of the furnace hearth clean by removing the remaining iron on the rotary furnace hearth or preventing the remaining after discharging reduced iron. SOLUTION: (1) At the time of producing the reduced iron by charging a mixed raw material consisting of powdery iron raw material and a powdery solid reducing agent into the rotary hearth furnace and burning, the reduced iron powder remaining on the furnace hearth is blown off with injected gas flow at a midway between the reduced iron discharging part to the raw material charging part and removed from the surface of the furnace hearth. (2) The same remaining powder is swept out by a broom having rotating blades and removed from the surface of the furnace hearth. (3) The same remaining powder is scraped with a scraper enabling reciprocating movement in the direction crossing the shifting direction of the furnace hearth by bringing the lower end thereof into contact with the furnace hearth and removed from the surface of the furnace hearth. (4) The same remaining powder is sucked through a sucking hood 16 fitted to above the furnace hearth and removed from the surface of the furnace hearth 2. (5) The remaining of the reduced iron powder 19 on the furnace hearth is prevented with a scraper type gate 20 fitted to the rear part of a fixed stopper fence 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rotating a raw material obtained by mixing a powdery iron raw material such as dust, sludge and scale containing powdery iron ore and iron and a powdery solid reducing agent such as coal and coke. When reducing iron is manufactured by loading it into a floor furnace (heating furnace in which the hearth rotates horizontally), the reduced iron powder remaining on the hearth is removed, or the reduced iron powder remains on the hearth. The present invention relates to a method for preventing the heat generation and keeping the hearth clean.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a technique of mixing a powdery iron ore and a powdery solid reducing agent to form an agglomerate and charging the resulting mixture to a rotary hearth to produce reduced iron.

[0003] Unlike a rotary kiln furnace which has been used for a long time, this rotary hearth furnace is characterized in that the equipment cost is low. On the other hand, since the hearth rotates horizontally, it is necessary to charge raw materials and discharge products. Care must be taken. As a typical example of the technology, a powdered iron ore is mixed with a solid reducing agent to form an agglomerate (pellet), which is heated to a high temperature to reduce iron oxide in the iron ore. (See, for example, US Pat. No. 3,443,9).
31, specification, JP-A-7-238307).

FIG. 1 is a schematic view showing an example of a conventional reduced iron production process in which heating is performed using a rotary bed furnace. As shown in the figure, bentonite as a binder is added to fine iron ore and fine coal, and water and tar are further added and mixed by a kneader. This mixed raw material is agglomerated by a pelletizer or a double-roll compressor, transferred to a raw material charging section of a rotary hearth furnace, charged into the furnace, and rotated once along with the movement of the hearth while the iron ore in the iron ore is rotated. Iron oxide is reduced at high temperature to form solid metallic iron. The obtained metallic iron is taken out from the discharge part.

[0005] In the above-mentioned method for producing reduced iron, as the powdered iron raw material, in addition to powdered iron ore, various dusts, sludges, scales, etc. containing iron generated in ironworks can be used. As the powdery solid reducing agent, coal, coke, char, oil coke and the like can be used.
These iron raw materials and solid reducing agents may be subjected to drying treatment and crushing treatment in some cases.

The powdered iron raw material and the powdered solid reducing agent are then kneaded. At this time, if necessary, water as a binder, tar, molasses, organic resin, cement, slag, bentonite, quicklime, Light dolomite and slaked lime are added.

The kneaded raw material is compacted into spherical pellets by a desk pelletizer or briquettes by a double roll compressor. In this case, a raw material having a particle size of 0.1 mm or less is suitable for forming a pellet, and a briquette having a particle size of 1 mm or less is suitable. . Further, in order to increase the strength of the agglomerate (refer to the above-mentioned pellets and briquettes), a drying treatment or a curing treatment may be performed after the agglomeration.

The agglomerates obtained are conveyed by belt conveyor to the upper part of a rotary hearth furnace, from where they are charged using a charging chute so as to be widely distributed on the rotary hearth and leveled by a leveler. Subsequently, it is reduced by heating while moving in the furnace and becomes metallic iron.

In the rotary bed furnace, a furnace temperature of 1100 ° C. to 1300 ° C. is secured by feeding and burning fuel gas and air into the furnace. The above-mentioned agglomerate was spread on the hearth of this rotary hearth furnace at a thin thickness of 10 to 20 mm, and the temperature was raised to 900 ° C. or more mainly by radiant heat from the furnace inner wall.
During the rotation, reduction sintering is performed while adjusting the rotation speed of the hearth so as to reach a predetermined metallization ratio, and the mixture is discharged from a discharge portion by a screw feeder.

FIGS. 2A and 2B are explanatory views of a method of discharging reduced iron by the screw feeder, wherein FIG. 2A is a top view of a rotary hearth, and FIG. 2B is a longitudinal sectional view near a discharge portion. As shown in the figure, the raw material (not shown) charged from the raw material charging section 1 onto the rotary hearth 2 is reduced at a high temperature by iron oxide in the raw material during one rotation accompanying the rotation of the hearth 2. The reduced iron is discharged from the product discharge section 3 by the screw feeder 4. After the reduced iron reaches the screw feeder 4,
The rotation of the screw moves in the direction orthogonal to the direction of movement of the hearth 2 (indicated by a white arrow in the figure) and is discharged to the outer peripheral side of the hearth 2. In this case, a fixed stopper fence 5 for storing the reduced iron product is provided behind the screw feeder 4 (on the hearth moving direction side, that is, on the downstream side). In the illustrated example, the rail 6 is attached to the lower side of the hearth 2, and the fixed wheel 7 is driven to drive the hearth 2.
Rotates at a constant speed. The inside of the furnace is sealed by seal water 8.

In the above-described reduced iron production process, when the agglomerate is charged into a rotary bed furnace, the agglomerate is pulverized to generate powder. In addition, even after charging, cracks occur during high-temperature reduction, and powder is generated. The powder generated in this way is reduced in the rotary hearth furnace to become metallic iron powder, but this iron powder does not pass through the gap between the stopper fence installed in the discharge part and the hearth and stays on the hearth without being discharged. With the rotation of the bed, the circulation is repeated such that the material is sent again to the raw material charging section and is heated, and stays in the rotary bed furnace.

The retained metallic iron powder remains metallic iron powder for about 60 minutes, but if it remains in the furnace for a longer time, the iron powder sinters and adheres to the hearth, and eventually the furnace The floor is coated with an iron plate, and in some cases, is thermally deformed, causing irregularities on the hearth surface. When such irregularities occur on the hearth surface, uneven firing occurs during firing of the raw materials, which not only greatly reduces the metallization rate of reduced iron, but also hinders the operation and causes major operational problems. It could also develop. Further, iron attached to hearth bricks may cause peeling cracks in the bricks when a mechanical force is applied thereto.

[0013]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the production of reduced iron, and removes metallic iron powder and deposits on hearth bricks remaining on the hearth, It is an object of the present invention to provide a method for maintaining a rotary hearth furnace which can prevent the metal iron powder from remaining and keep the hearth surface clean at all times.

[0014]

The gist of the present invention resides in the following (1) to (5) methods for maintaining a rotary bed furnace.

(1) A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and baked to produce reduced iron, and the reduced iron powder remaining on the hearth is reduced. A method for maintaining a rotary hearth, comprising blowing off the iron from the hearth between the iron discharge part and the raw material charging part by a jet gas flow.

(2) A mixed raw material of a powdered iron material and a powdered solid reducing agent is charged on a rotary hearth, and when reduced iron is produced by firing, the reduced iron powder remaining on the hearth is reduced. A method for maintaining a rotary hearth, comprising: sweeping out of a hearth with a broom provided with rotating blades between an iron discharge part and a raw material charging part.

(3) A mixed raw material of a powdered iron material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron. Can be reciprocated in the direction intersecting with the moving direction of the hearth between the reduced iron discharge part and the raw material charging part, and scraped from the hearth by scraping the lower end into contact with the hearth. A method for maintaining a rotary hearth, which comprises removing.

(4) A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron, and the reduced iron powder remaining on the hearth is reduced. A method for maintaining a rotary hearth, wherein suction is performed through a suction hood provided between an iron discharge part and a raw material charging part, and the rotary hearth is removed from the hearth.

(5) A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron. A method for maintaining a rotary hearth, characterized in that reduced iron powder is prevented from remaining on the hearth by a scraper-type gate provided with the lower end of the fixed stopper fence of the device on the hearth moving direction side in contact with the hearth.

Here, the "pulverized iron raw material" is a powdered iron raw material containing iron oxide as a main component, and specifically includes the above-mentioned powdered iron ore and iron generated in an ironworks. Waste, sludge (eg, sintering machine generated dust, blast furnace generated dust, converter generated dust, rolling plant generated sludge), scale, and the like. In the present invention, these can be used alone or in a mixture of two or more.

The "powder solid reducing agent" is a powder of a solid substance mainly containing carbon, such as coal, coke, char and oil coke. These can also be used alone or in combination of two or more.

As described above, the "reduced iron powder remaining on the hearth" is, as described above, iron powder generated by reducing powder generated at the time of charging raw materials, or cracks generated during reduction firing or mining. Iron powder, and "fixed matter" refers to a substance in which reduced iron powder stays in the furnace for a long time, and as a result, the iron powder sinters and adheres to the hearth.

The term "maintenance of the hearth" as described above means that the reduced iron powder and the adhered substances are not left on the hearth surface or are removed to keep the hearth surface clean at all times. Say.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention (the above (1) to
The invention (5) will be described in detail.

According to the invention of (1), as described above, the reduced iron powder remaining on the hearth is blown off by a jet gas flow from the discharge part of the reduced iron to the raw material charging part and removed from the hearth. This is a method for maintaining the hearth surface clean. In addition,
"Between the reduced iron discharge section and the raw material charging section" refers to the raw material and the reduced iron produced by the reduction from the reduced iron discharge section to the raw material charging section in the moving direction of the hearth. Is a section on the hearth where no is placed. This is the same in the inventions (2) to (4) described below.

FIG. 3 is an explanatory diagram of an example of this method.
The figure shows a cross section perpendicular to the moving direction of the hearth. As shown in the figure, a gas injection nozzle 9 is disposed diagonally from above toward the hearth surface.

In the method (1) of the present invention, the gas is injected from the gas injection nozzle 9 to blow off the residual reduced iron powder 10, thereby keeping the hearth surface clean.

The angle of the gas injection nozzle with respect to the hearth surface and the height from the hearth surface are not particularly limited. An appropriate adjustment is made so that the reduced iron powder can be effectively blown off and removed from the hearth.

The gas may be injected from the nozzles arranged side by side in the direction perpendicular to the direction of movement of the hearth in the direction of movement of the hearth 2, as shown in the figure. It is desirable to use a gas injection nozzle 9 that can reciprocate in a direction that is close to or in the direction in which the nozzle 9 moves, and that the nozzle 9 reciprocates as shown by the arrow in the figure.

When the cross-sectional shape of the gas injection nozzle is circular or close to it, it is desirable to use not a single gas injection nozzle but a plurality of gas injection nozzles in parallel in the circumferential direction of the hearth. Further, like the nozzle used in the embodiment, a nozzle having a flat cross section at the tip of the nozzle and extending in the circumferential direction of the hearth may be used.

The type of gas to be injected is not particularly limited, but nitrogen gas is preferable from the viewpoint of protecting the hearth brick and preventing reoxidation of the remaining reduced iron powder. The gas injection pressure is not limited, and may be appropriately adjusted so that the reduced iron powder can be effectively removed from the hearth.

In the invention of (2), the reduced iron powder remaining on the hearth is removed from the hearth by sweeping it with a broom equipped with rotating blades from the discharge part of the reduced iron to the raw material charging part. This is a method of keeping the hearth surface clean. The term `` broom with rotating blades '' as used herein refers to a broom having a cleaning function of sweeping out residual reduced iron powder on the hearth, and is not limited to a broom having blades or blade-like ones.
A broom (usually referred to as a "brush") having a hair-like shape having a certain hardness and thickness may be used.

The broom having rotating blades is, for example, a cylindrical broom having a cleaning brush around it, and is configured to be rotatable (that is, rotatable) in the forward and reverse directions about the axis of the cylinder as a rotation axis. What is done may be used. The rotary blade broom 13 shown in the enlarged view of FIG. 4 described below corresponds to this.

A broom equipped with such rotating blades is used. The broom is rotated in the forward or reverse direction as appropriate, and the residual reduced iron powder is reciprocated in a direction orthogonal to or close to the direction of movement of the hearth. Sweep out and remove from hearth.

FIG. 4 is an explanatory view of a preferred example of the method of the invention (2). The figure shows a cross section perpendicular to the moving direction of the hearth.

In this embodiment, a broom having rotating blades is a cylindrical broom having a cleaning brush 11 around it, and is rotatable in the normal and reverse directions around the cylindrical shaft 12 as a rotation axis. A plurality of blade brooms 13 (see an enlarged view) are connected in a direction orthogonal to the axis of the cylinder to form a group of rotating rotary brooms 14. That is, the rotating blade broom group 14 is moved from the reduced iron discharge section to the raw material charging section,
A plurality of rotating brooms 13 are arranged in the width direction of the hearth 2 (two are arranged in the illustrated example), and the rotating brooms 13 constituting the rotating broom group 14 are appropriately rotated in the forward direction or the reverse direction, and the circular rotation is performed. The ring of the broom group 14 is rotated in a forward or reverse direction in a direction orthogonal to or close to the moving direction of the hearth 2 to remove residual reduced iron powder on the hearth. One annular rotating blade broom group 14 may be arranged on the hearth, and may be reciprocated in a direction orthogonal to or close to the moving direction of the hearth 2 while rotating as described above.

The use of the ring-shaped rotating blade broom group makes it possible to efficiently remove the remaining iron powder in a short time and keep the hearth surface clean.

The width of the rotating blade broom (the length in the direction of the rotating shaft) is
Although not particularly limited, it is desirable that the width is approximately equal to the width of the rotary hearth.

Although the moving speed of the rotating blade broom is not particularly limited, if the entire hearth surface is cleaned with a rotating blade broom having a width approximately equal to the width of the hearth, it is at least equal to or higher than the moving speed of the hearth. Speed.

According to the invention of (3), the reduced iron powder and the adhered substances remaining on the hearth are removed by scraping with a scraper between the reduced iron discharge part and the raw material charging part, and the hearth surface is removed. Is a method of maintaining the cleanliness.

FIG. 5 is an explanatory diagram of an example of this method.
The figure shows a cross section perpendicular to the moving direction of the hearth. As shown in the drawing, the scraper 15 has a lower end in contact with the hearth surface, and is configured to be able to reciprocate in a direction intersecting the moving direction of the hearth 2. The direction intersecting with the direction of movement of the hearth is a direction orthogonal to the direction of movement of the hearth or a direction close thereto (a direction making an angle of 20 ° or less or −20 ° or more with respect to the orthogonal direction).
Say.

In the method of the invention (3), the scraper is reciprocated in a direction intersecting the moving direction of the hearth while scraping the reduced iron powder and the adhered matter remaining on the hearth and removing it from the hearth. From the viewpoint of shortening the moving distance of the scraper, it can be said that it is desirable to reciprocate in the direction orthogonal to the moving direction of the hearth. As shown in the figure, if a proper angle is formed at the tip of the scraper, the scraping effect is large, and the adhered matter adhered to the hearth can be removed.

The width of the scraper is desirably about the same as the width of the rotary hearth.

The moving speed of the scraper has a width approximately equal to the width of the hearth, and if the scraper reciprocating in the direction perpendicular to the moving direction of the hearth is intended to clean the entire hearth surface, the following is required. The scraper must be moved back and forth in preparation for the scraping of the hearth, so that the moving speed of the hearth must be at least twice as high. For example, the rotating hearth has a width of 5 m
If the rotation speed is about 12 m / min, the width 5
m using a scraper with an average moving speed of 24 m / mi
If n or more, the reduced iron powder and the adhered matter can be removed within 0.20 minutes (one way, that is, from the inner circle to the outer circle of the hearth) at one time.

According to the invention (4), the reduced iron powder remaining on the hearth is sucked by a suction blower or an ejector system through a suction hood provided between a discharge portion of the reduced iron and a material charging portion, and In this method, the hearth surface is kept clean by removing it from the hearth.

FIG. 6 is an explanatory diagram of an example of a case where suction is performed by a suction blower in this method. The figure shows a cross section perpendicular to the moving direction of the hearth.

As shown in the figure, a suction hood 16 (in the example shown, divided into six sections) is provided on the hearth between the reduced iron discharge section and the raw material charging section. The suction hoods 16 are finally combined into one tube and connected to a suction blower 18 via a bag filter 17. Reduced iron powder remaining on the hearth
It is sucked by the suction blower 18 and collected by the bag filter 17.

The suction hood is desirably provided over the entire width of the hearth 2.

This method is particularly effective for removing iron powder that has not been reduced for less than about 60 minutes after being reduced.

The invention of (5) is a method for keeping the surface of the hearth clean by minimizing the residual of the reduced iron powder on the hearth. This is a method in which a scraper-type gate is provided on the furnace floor moving direction side of a fixed stopper fence of a commonly used screw feeder-type mining apparatus, that is, on the downstream side.

FIG. 7 is an explanatory diagram of an example of this method.
The figure shows a vertical section parallel to the moving direction of the hearth (indicated by an arrow in the figure). As shown in the drawing, the lower end is brought into contact with the hearth surface of the fixed stopper fence 5 provided behind the screw feeder 4 (downstream side) for holding the reduced iron products 21 on the hearth moving surface. A gate 20 is provided.

Although there is a slight gap between the fixed stopper fence 5 and the hearth surface, this gap gradually increases due to wear of the reduced iron and the hearth surface when discharging the reduced iron. Therefore, the reduced iron powder 19 stays on the hearth without slipping through the gap and being discharged, and is repeatedly sent to the raw material charging section with the rotation of the hearth and is heated again. Stay. Therefore, a scraper-type gate 20 is provided on the side of the hearth moving direction of the fixed stopper fence 5.
Is provided. Since the scraper type gate 20 is configured to be lightly pressed against the hearth 2 surface from above and to be in contact with the hearth surface to close a gap between the scraper type gate 20 and the hearth surface, the fixed stopper fence 5 and the hearth The scraper-type gate 20 prevents passage of the reduced iron powder 19 even if the gap between the furnace and the surface is passed, prevents the reduced iron powder 19 from remaining on the hearth, and keeps the hearth surface clean.

The installation position of the scraper type gate 20 is as follows.
As long as there is no problem in lightly pressing the gate 20 on the hearth 2, it is desirable to mount the gate 20 immediately behind the fixed stopper fence 5, that is, in close contact with the stopper fence 5 as illustrated. The scraper-type gate 20 should be divided in the width direction so as to cope with a case where the gap (interval) between the fixed stopper fence 5 and the hearth surface is different in the width direction of the hearth. Is desirable.

According to this method, the hearth can be maintained clean by preventing the reduced iron powder from remaining on the hearth.

The inventions of the above (1) to (5) can be applied to powder, pellets,
This is a technique that can be applied to any case such as brick, tile, plate, and sheet.

Each of these methods is effective even if it is performed independently. For example, the method of attaching the stopper fence of (5) and the method of any one of (1) to (4), Alternatively, the effect can be further enhanced by combining a plurality of methods such as the method of (1) or (4) and the method of scraping with the scraper of (3).

According to the method of the present invention, the reduced iron powder and the solid matter adhered to the brick are discharged out of the furnace at the discharge section of the reduced iron in the rotary bed furnace, or the reduced iron powder is prevented from remaining on the hearth. Thus, the hearth surface can be kept clean. As a result, it is possible to prevent uneven firing due to the occurrence of unevenness on the hearth surface due to the adhesion of reduced iron powder, etc., to suppress a significant decrease in the metallization rate of reduced iron, and to prevent operational problems beforehand. In addition, cracks in the hearth brick can be prevented.

[0058]

EXAMPLES Using the fine iron ore shown in Table 1 and the fine coal shown in Table 2 and blending them at the blending ratio shown in Table 3, the powders of No.
1 to No. In the method shown in Case 6, reduced iron is produced while removing the iron powder remaining on the hearth or without leaving the reduced iron powder on the hearth, and the metallization ratio of the reduced iron at this time indicates the present invention. The effect was evaluated.

In the production of reduced iron, following the production process shown in FIG. 1, the blended raw materials are mixed, molded into briquettes by a double roll compressor, and then charged into a rotary bed furnace and fired. It was done by doing. Table 4 shows the equipment specifications and operating conditions of the rotary hearth furnace used.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

[0064]

[Table 5]

No. Case 1 is a conventional example, in which the reduced iron is discharged by the screw feeder shown in FIG. 2 and then the operation is performed without removing the reduced iron powder remaining on the hearth.

No. 2-No. The case of No. 6 is an example of the present invention. 2 indicates that when N ₂ is injected from the gas injection nozzle shown in FIG. 3 to blow off and remove the residual reduced iron powder,
o. No. 3 shows a case where the residual reduced iron powder was removed by a group of rotary blades connected to a number of rotary blades shown in FIG. 4
In the case of No., when the residual reduced iron powder was removed by the scraper shown in FIG. In the case of No. 5, when the residual reduced iron powder was removed by the suction hood shown in FIG. 6
In the case (1), the scraper-type gate shown in FIG. 7 prevents the reduced iron powder from remaining on the hearth.

Table 5 shows the metallization ratio of reduced iron in each case. In the present invention, the metallization ratio of reduced iron could be maintained higher than in the conventional example. This is because, in the example of the present invention, the reduced iron powder remaining on the hearth was removed every time the reduced iron was discharged, or the reduced iron powder was prevented from remaining on the hearth, resulting in reduced uneven firing. .

[0068]

According to the method of the present invention, iron powder generated by reduction at the discharge section of the reduced iron in the rotary bed furnace and the adhered matter to the bricks are discharged to the outside of the furnace to remove or reduce the reduced iron powder. Can be prevented from remaining on the hearth, and the hearth surface can be kept clean. As a result, it is possible to prevent uneven firing and to suppress a large decrease in the metallization ratio of reduced iron, thereby preventing operational troubles.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a conventional reduced iron production process performed using a rotary hearth furnace.

FIG. 2 is an explanatory view of a conventional method for discharging reduced iron from a rotary bed furnace.

FIG. 3 is a diagram illustrating an example of a method for removing reduced iron powder or the like remaining on a hearth according to the present invention, in which a gas injection nozzle is used.

FIG. 4 is an explanatory view of an example of the method for removing reduced iron powder and the like remaining on the hearth of the present invention, in which a rotating blade broom group is used.

FIG. 5 is an explanatory view of an example of a method for removing reduced iron powder or the like remaining on a hearth according to the present invention, in which a scraper is used.

FIG. 6 is an explanatory view of an example of a method for removing reduced iron powder or the like remaining on a hearth according to the present invention, in which a suction hood is used.

FIG. 7 is an explanatory view of an example of a method for preventing reduced iron powder or the like from remaining on a hearth according to the present invention, in which a scraper type gate is used.

[Explanation of symbols]

 1: Raw material charging section 2: Rotating hearth 3: Product discharge section 4: Screw feeder 5 Stopper fence 6: Rail 7: Wheel 8: Seal water 9: Gas injection nozzle 10: Residual reduced iron powder 11: Cleaning brush 12: Shaft 13: Rotating blade broom 14: Rotating blade broom group 15: Scraper 16: Suction hood 17: Bag filter 18: Suction blower 19: Reduced iron powder 20: Scraper type gate 21: Reduced iron product

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Masahiko Hoshi 4-5-33 Kitahama, Chuo-ku, Osaka City, Osaka Inside Sumitomo Metal Industries, Ltd.

Claims (5)

[Claims] 1. A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron.
A method for maintaining a rotary hearth, characterized in that reduced iron powder remaining on the hearth is blown away from the hearth between the reduced iron discharge part and the raw material charging part by a jet gas flow to remove the reduced iron powder from the hearth. 2. A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron.
A method for maintaining a rotary hearth, wherein the reduced iron powder remaining on the hearth is removed from the hearth by sweeping with a broom equipped with rotating blades between the reduced iron discharge part and the raw material charging part. . 3. A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron.
The reduced iron powder and solids remaining on the hearth can reciprocate in a direction intersecting with the direction of movement of the hearth between the reduced iron discharge part and the raw material charging part, and the lower end can be moved to the hearth. A method for maintaining a rotary hearth, wherein the scraper is scraped off from the hearth with a scraper in contact therewith. 4. A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron.
A method for maintaining a rotary hearth, wherein the reduced iron powder remaining on the hearth is sucked through a suction hood provided between a reduced iron discharge part and a raw material charging part, and removed from the hearth. 5. A mixed raw material of a powdered iron raw material and a powdered solid reducing agent is charged on a rotary hearth and fired to produce reduced iron.
Preventing the reduction iron powder from remaining on the hearth by means of a scraper-type gate provided with the lower end in contact with the hearth on the hearth moving direction side of the fixed stopper fence of the mining equipment provided at the reduced iron discharge part A method for maintaining a rotary hearth.