JP2968122B2 - Disassembly and repair method for refractories lining electric furnaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of disassembling and repairing a refractory lining of an electric furnace for steelmaking, which can save labor and shorten working time by using a dismantling robot.

[0002]

2. Description of the Related Art Some electric furnaces for steelmaking use direct current and alternating current as a power source, and those having a capacity of 40 to 100 tons are usually used. The approximate size of these steelmaking electric furnaces is an outer diameter of 3.5 to 7 m and an inner diameter of 3 to 6.5.
m, depth (with the lid removed) 3.5-4.5 m, which is mounted on a table with a rocker-type tilting device attached, and usually below the electric furnace. About 1
A space with a height of 0 m is provided.

In the prior art, repairing the refractory lining of an electric furnace for steel making requires severe work with a bad environment and danger, and usually requires a considerably long cooling time in addition to the time required for the work. And

[0004] More specifically, after the operation of the electric furnace is stopped, the lid of the electric furnace is removed and cooling is started.
After about 2 hours, the mixture of molten metal and slag (commonly referred to as slag) remaining in the furnace solidifies. In some cases, water is sprayed into the furnace so that workers can enter the furnace as soon as possible. However, if watering is started before the noro solidifies, steam explosion may occur, so it usually takes about 2 hours. After cooling down, forced cooling by watering is started.

[0005] Watering is performed by a worker rising to the upper deck of the electric furnace and discharging water from a hose. However, when a large amount of water is intensively sprayed, the refractory lining is locally cooled and the water is joined to the joint of the refractory. Intermittently, it penetrates to the back through the joint and water penetrates into the permanent bricks that are not damaged and do not need to be replaced, rapidly cooling and damaging the permanent bricks. Careful cooling is achieved by careful watering.

[0006] If it is determined that the worker is allowed to cool down for about 6 hours after the stoppage of the operation, or to cool it down for two hours after the stoppage of the operation and then forcibly cool it by watering and put the worker into the electric furnace, Air hammer used for dismantling refractories,
The shovel, cans for dismantled waste, etc. are suspended by a crane from above the electric furnace into the electric furnace and carried.

[0007] Next, the worker wears heat-resistant safety shoes, protective glasses, a dust-proof mask, a helmet, gloves, long-sleeved work clothes, etc., and enters the furnace. The temperature of the furnace wall at this time was about 120
° C and the atmosphere temperature in the furnace are 50 ° C or higher. The worker entering the electric furnace first removes the slag with an air hammer, and then moves on to dismantling the refractory lining.

[0008] This disassembly work is usually carried out by a group of about three workers. At this time, severe hot air still remains in the electric furnace, and intense force work is performed.
Every 5 minutes, the work is carried out by replacing another group of workers waiting outside the electric furnace.

The dismantled refractory waste material is put into a can by a shovel by an operator, and when the can is full, it is lifted and taken out by a crane, and an empty can is hung in a furnace by a crane. Instead of using cans, there is a method in which waste materials are continuously carried out by a belt conveyor, but there is not much difference in working time.

[0010] The dismantling of the refractory lining requires a total of about 5 hours of work to dismantle all the refractory lining except for the permanent bricks.

The repair interval of the refractory lining of the electric furnace is 1-2.
In many cases, it is as short as a week, and shortening the time required for this repair is one of the important requirements for improving the productivity of the electric furnace.
The time required for disassembly and repair of the electric furnace is required for the cooling time a until the worker enters the furnace after the operation is stopped, for removing the slag adhered to the inner surface of the furnace, for dismantling the lining refractory and removing the waste material of the refractory. Time b and time c required for construction of refractory lining
Is the sum of

For example, a is 6 hours, b is 5 hours, c is 10 hours, etc. The time a can be considerably reduced by forced cooling by watering. However, watering often damages refractories that do not require replacement, and is not a preferred method. On the other hand, when the forced cooling by watering is not performed, a long cooling time is required.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for dismantling and repairing a lining refractory which can simultaneously solve many problems in dismantling and repairing a lining refractory of an electric furnace.

[0014]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and a method of disassembling and repairing a refractory lining of an electric furnace according to the present invention comprises the steps of: At the time of dismantling, the central part of the hearth of the electric furnace was made removable, and the central part of the hearth was removed,
Attach a gantry having a floor surface on which the dismantling robot can be placed above the upper end of the opening, taking the area of the floor smaller than the area of the opening, and connecting the edge of the floor and the upper edge of the opening. A gap of an appropriate width is provided between them, the dismantling robot is operated by placing the dismantling robot on the floor of the gantry, disintegrating the refractory lining by the mechanical force of the dismantling robot, and disposing the waste material of the dismantled refractory. It is characterized in that an operation of dropping from a gap into a container arranged below the opening is performed.

In a preferred embodiment of the method for dismantling and repairing a refractory lining of an electric furnace according to the present invention, the gap is set to 0.6 m or more. In another preferred embodiment of the method for dismantling and repairing an electric furnace lining refractory according to the present invention, an operator and / or a dismantling robot entering the electric furnace is placed in the electric furnace during the initial stage of the dismantling operation of the electric furnace lining refractory. The refractory is dismantled by suspending a cylindrical shield for shielding from the remaining hot air from above the electric furnace.

In another preferred embodiment of the method for disassembling and repairing a refractory lining of an electric furnace according to the present invention, the method comprises the steps of:
Attach a floor surface with a hole larger than the opening, place a disc-shaped scaffold in the center of the hearth, and cool the internal workers by blowing outside air from above with a bellows tube inside the cylindrical shield. To

In another preferred embodiment of the method for disassembling and repairing a refractory lining of an electric furnace according to the present invention, the opening is formed in a circular shape, and the container is placed on a cart so as to be movable.

In another preferred embodiment of the method for dismantling and repairing a refractory lining of an electric furnace according to the present invention, a spare of a central portion of a detachable hearth is separately prepared, and a lining is provided in advance on a central portion of the spare hearth. After refractory work has been completed, the center part of the hearth will be replaced after dismantling.

[0019] in order to dismantling method of repairing an electric furnace refractory lining according to the invention applied practice, refractory lining which is construction in the central portion of the hearth of the electric furnace provided with openings and detachable, and the furnace A refractory is also installed on the side of the object so that the refractory at the boundary of the opening can be easily cut off.

For example, an irregular-shaped refractory such as a stamp material is applied to a portion which becomes a boundary of the opening provided in the hearth, and the work of disassembling the lining refractory can be started by cutting the stamp material.

After the operation of the electric furnace is stopped, in order to start dismantling work of the refractory lining of the electric furnace within a short time, first, the cylindrical shield is suspended in the electric furnace by a crane.
At the bottom of this cylindrical shield, a floor provided with a hole preferably in a donut shape is attached, and the size of the hole of this floor is about 0.2 m or more in diameter from the size of the opening to be opened in the hearth. Has been enlarged.

It is preferable that a cooling air tube is circulated around the cylindrical shield, including the floor, and air is flowed through the tube to cool the tube. In addition, a scaffold of a size smaller than the size of the opening having the same shape as the opening, preferably a disk-shaped scaffold, is placed at the center of the hole of the donut-shaped floor, and the tip of the bellows tube is placed inside the cylindrical shield. It is preferable that the outside air sent from the blower is sent from the bellows tube to the inside of the cylindrical shield to protect the worker from hot air.

Next, an operator enters the inside of the cylindrical shield and uses a tool such as an air hammer to remove the stamp material of the hearth constructed inside the donut-shaped floor and around the disk-shaped scaffold. Cut off part. Irregular refractories, such as stamp materials, are easier to break down than lining refractories of regular refractories, but sintering is progressing due to high heat during operation, and it is difficult to cut off unless cutting is performed.

The work of providing an opening is performed by repeatedly pressing a hydraulic jack under the center of the hearth, pushing up with the hydraulic jack, loosening and pushing up again, thereby cutting off the refractory at the boundary of the opening. Can be.

After the lining of the refractory lining is completed, the opening is formed by pulling down the center of the hearth with a hydraulic jack downward or hanging it with a rope and lifting it up with a crane. Whether the central part of the hearth is lifted up or down is determined by setting the structure of the hearth to any suitable structure. The structure for mounting the refractory and the method for lining the refractory are designed to be able to be pushed into the furnace .

Next, a gantry having a floor on which the dismantling robot is mounted is attached to the opening. At this time,
It is also possible to fix it on the container for refractory waste, but move the lower container of the furnace during operation,
When the container is full of refractory waste, you can move the container and replace it with an empty container,
Preferably, the lower end of the foot is fixed to the lower end of the opening.

The gantry is suspended from above with a crane,
It can be lifted from below, but in many cases it is convenient to drop it from above with a convenient crane. In a state where the gantry is fixed, the gap between the rim of the floor of the gantry and the upper edge of the opening of the hearth is preferably 0.6 mm on average.
m or more, and preferably 0.8 m or more on average, from which the dismantled refractory waste material is dropped downward and easily stored in a container.

The size of the gap can be ensured by increasing the step between the upper end of the floor opening and the floor, or by increasing the size of the opening relative to the size of the floor. If the gap is small, refractory waste will be caught in the gap and it will be difficult to discharge the refractory waste.If the size of the opening is too large, it will be difficult to receive the waste unless the container is enlarged, and the floor of the gantry If the step between the surface and the upper end of the opening becomes high, the installation of the robot becomes unstable, so it is preferably 1.5 m or less, more preferably 1.2 m or less.

Next, the dismantling robot is suspended and installed on the floor of the gantry by a crane. When the dismantling robot is lifted and lowered by the crane, if the lifting height of the crane can be sufficiently obtained, the gantry can be mounted in advance under the dismantling robot, and can be lifted and installed.

Next, the cylindrical shield is lifted with a crane and taken out of the furnace, and the worker who climbs on the deck on which the lid of the electric furnace is mounted remotely controls the dismantling robot while watching the movement of the dismantling robot. Then, the refractory lining is broken down by the nails of the demolition robot and dismantled, and waste material of the refractory is dropped into a container placed under the opening.

The dismantling robot performing this operation does not require complicated operations, so that the dismantling robot is not expensive and easy to operate. The container is preferably placed on a trolley so that once the container is filled with refractory waste material, the trolley can be moved and replaced with another container.

In the initial stage of the dismantling operation, it is not always necessary to take out all of the cylindrical shield outside the furnace, and when a donut-shaped floor surface having a hole larger than the opening is attached to the bottom of the cylindrical shield. In addition, by removing only the floor surface, the refractory other than the corners of the hearth can be dismantled by a demolition robot, and refractory lining can be performed on this part. If the refractory on the side wall of the electric furnace is dismantled after removing the cylindrical shield from the inside of the electric furnace after the dismantling, it is possible to reduce the amount of hot air in the furnace that is received by a worker or a dismantling robot.

The shape of the opening provided in the hearth may be square or polygonal, but it is easy to cut off and the shape is circular in order to avoid the thermal stress from being concentrated on a part of the furnace shell. Is preferred. In addition, by preparing a reserve for the central part of the hearth and pre-installing the refractory lining on the upper part of the central part of the hearth, the time required for the construction of the refractory in this part is reduced. It is possible.

Disassembly and repair of the refractory lining of an electric furnace may be performed both over the entire surface and when disassembling and repairing only a part of which is greatly damaged. A gas injection nozzle which accelerates the consumption of the refractory on the hearth of the electric furnace. If a gas blow nozzle is installed at the center of the spare hearth, the dismantling and repair of this part can be completed in a shorter time when the (provided for stirring the molten steel) is installed.

By adopting the method for dismantling and repairing the refractory lining of an electric furnace according to the present invention, it is possible to avoid heavy work in a severe working environment by an operator, and it is not necessary to perform forced cooling by watering after the operation of the electric furnace is stopped. However, the dismantling work can be started after cooling down for a relatively short time, and the dismantling of the refractory lining can be advanced efficiently using the mechanical power of the robot. The time required for disassembly and, consequently, the time required for disassembly and repair of the electric furnace can be remarkably reduced, and the operating rate of the electric furnace can be further improved by the shortened disassembly and repair time.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0037]

【Example】

Test Example 1 An operation of repairing all the refractory linings (excluding permanent bricks) of a steelmaking electric furnace (capacity: 90 tons) having an inner diameter of 6.6 m was attempted by the dismantling repair method of the present invention.

The refractory lining 2 of the electric furnace 1 is, for example, as shown in FIG.
The refractory 2 of the hearth has a beam structure. In order to apply the method for dismantling and repairing a refractory lining according to the present invention by using the conventional refractory lining as it is, for example, a furnace floor having a diameter of about 3 m is used.
A central portion 3 capable of opening is provided, and the central portion 3 is pulled down and removed to form an opening.

When the refractory lining of an electric furnace is constructed,
A stamp material 9 corresponding to a thickness of about one refractory (about 15 cm) is previously driven into a portion corresponding to the contour of the opening. The wall 7 on the upper part of the electric furnace is cooled by a coil-shaped water cooling tube, and no refractory is applied or the spraying material is thinly applied.

On the left side of the electric furnace shown in the figure, there is provided a gate 5 for pouring molten steel melted inside the electric furnace, and on the right side there is an input port 6 for inputting scraps of steel as a raw material. The refractory on the side wall of the electric furnace has a two-layer structure of a permanent refractory 4 used repeatedly and a refractory lining 2 which wears out and is replaced each time.

When the refractory lining 2 is worn out after a certain period of operation and the refractory needs to be replaced, the donut shown in FIG. 3 has a hole larger than the opening formed in the hearth. The cylindrical shield 8 with the floor 11 shaped like a floor attached to the bottom is hung on a lifting part 10 and suspended by a crane (not shown) into an electric furnace as shown in FIG.

Next, the bellows tube 12 connected to the blower is dropped from above the cylindrical shield to blow outside air, and a disk-shaped scaffold 13 having an outer diameter smaller than the opening provided in the hearth is placed at the center of the hearth. The operator enters the furnace with the air hammer 14, scrapes off the sticks attached to the boundary of the opening, and pierces the stamp material 9, which is circularly formed below, with the air hammer 14. Break down.

When the stamp material 9 has been removed to some extent,
The upper surface of a jack (not shown) is placed below the center of the hearth, the bolt 15 fixing the center 3 of the hearth is removed, and the center 3 of the hearth is pushed up by the jack, and the stamp material is removed. Cut the refractory lining at the place where it was set.

When the refractory is cut off at the boundary of the center part 3 of the hearth, the center part 3 of the hearth is lowered with a jack and is drawn downward to form an opening. Flange 16 attached to the lower end of the opening from which the center of the hearth has been removed
Having an inner diameter slightly smaller than the inner diameter of the opening
7 is fixed with bolts 18 as shown in FIG.
The gantry 19 is suspended from the crane 7 and installed. At this time, the gap between the upper edge of the edge and the opening 23 of the floor 25 of the gantry 19 is about 0.8 m.

Next, the container 22 is placed on the carriage 21 moving on the rail 20 and moved below the electric furnace, and the container 22 is arranged below the opening 23 in the hearth. Pull the bellows tube 12 connected to the blower from the electric furnace, removed from the electric furnace circular <br/> tubular shield 8 with a crane, the floor 25 of the gantry 19 demolition robot 24 by a crane
Install on top and secure.

The operator rides on the deck 26 of the electric furnace and observes the operation of the robot 24 while watching the operation panel 27 of the robot 24.
To operate the claw 2 attached to the tip of the arm of the robot 24.
The refractory lining 2 consumed by 8 is dismantled, and the refractory waste material dismantled from the opening 23 is dropped and stored in the container 22.

In the conventional method for dismantling and repairing refractories lining electric furnaces without water spraying in a hot electric furnace, it took about 6 hours to cool the electric furnace after the operation was completed and 5 hours for dismantling work. According to the method for dismantling and repairing the refractory lining of an electric furnace according to the present invention, the cooling time can be reduced to about 2 hours, and the working time can also be reduced to about 3 hours. Also, the time required for the construction of the refractory lining was reduced from about 10 hours in the past to about 7 hours by previously constructing the refractory in the upper part of the hearth.

In this example, the total time spent repairing the refractory lining of the electric furnace was reduced to about 12 hours with the method according to the invention compared to 21 hours with the conventional method.

Test Example 2 Partial disassembly of a hearth provided with a gas injection nozzle at the center of a hearth in an electric furnace (capacity: 90 tons) having an inner diameter of 6.6 m and a gas injection nozzle attached to the hearth. Attempted repair. In other words, there is a case where the side wall of the electric furnace is reused as it is because the side wall of the electric furnace is less worn, and only the hearth portion which has been worn out is disassembled and repaired.

In the same procedure as in Test Example 1, after the operation of the electric furnace was completed, the center of the hearth of the electric furnace in which the gas injection nozzle was incorporated was removed to form an opening, and the cylindrical shield was electrically connected. The dismantling robot was installed on the floor of the gantry fixed to the opening while being placed in the furnace, and the refractory lining of the electric furnace was dismantled.

Separately, the center part of the hearth on which the refractory lining with the gas injection nozzle is installed is prepared in advance, and the refractory lining of the hearth is disassembled. The electric furnace was dismantled and repaired according to the procedure of installing the part in the opening and installing the refractory lining on the dismantled hearth except the center.

In the disassembly and repair work of the electric furnace, when the disassembly and repair work was performed by the conventional method, it took 6 hours for cooling, 3 hours for dismantling, and 7 hours for construction of the refractory lining. By applying the method for repairing the dismantling of the electric furnace according to the present invention, it takes 2 hours for cooling, 1 hour for dismantling, and 1 hour for the construction of the refractory lining. Was done.

FIG. 2 is a sectional view showing an example of a structure of the hearth which is convenient for forming the opening by pushing up the center part 3 of the hearth of the electric furnace 1. The inner refractory 2, the stamp material 9, and the lower mounting structure 3 at the center 3 of the hearth are constructed so as to be pushed upward and removed.

[0054]

According to the method for dismantling and repairing the refractory lining of an electric furnace according to the present invention, by providing an opening in the center of the hearth, most of the dismantling and repair work performed in a high-heat environment is performed. Since the robot can be efficiently operated by the mechanical power of a dismantling robot that performs simple operations, workers can be released from dangerous heavy work that was performed in a high-temperature environment, and the operation is terminated by using a cylindrical shield. The time required for subsequent cooling of the electric furnace can be greatly reduced, and the center part of the hearth on which the refractory has been separately prepared is prepared in advance, and the center part of the hearth is replaced, so that it is necessary for dismantling and repair. The time was further shortened, and the time required for dismantling and repair was shortened, making it possible to improve the operating rate of the electric furnace.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a steelmaking electric furnace configured to apply a method for dismantling and repairing a refractory lining of an electric furnace according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the steelmaking electric furnace configured to apply the method for dismantling and repairing the refractory lining of the electric furnace according to the present invention.

FIG. 3 is a perspective view showing an example of a cylindrical shield used in the method for dismantling and repairing a refractory lining of an electric furnace according to the present invention.

FIG. 4 is a cross-sectional view of a steelmaking electric furnace for explaining an example of a method of disassembling and repairing a refractory lining of the electric furnace according to the present invention.

FIG. 5 is a cross-sectional view of a steelmaking electric furnace for explaining an example of a method of disassembling and repairing a refractory lining of the electric furnace according to the present invention.

[Explanation of symbols]

 1: Electric furnace 2: Lined refractory 3: Central part of hearth 4: Permanent brick 5: Sluice 6: Input port 7: Upper wall surface 8: Cylindrical shield 9: Stamp material 10: Lifting part 11: Donut shape Floor 12: bellows tube 13: Scaffold 14: Air hammer 15, 18: Bolt 16, 17: Flange 19: Stand 20: Rail 21: Dolly 22: Container 23: Opening 24: Demolition robot 25: Floor surface 26: Deck 27 : Operation panel 28: Claw

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C21C 5/52 C21C 5/52 (72) Inventor Hidemi Hirano 4976 Nomura Minamimachi, Shinnanyo-shi, Yamaguchi Prefecture Nisshin Steel Corporation Shunan Steel Works (56) References JP-A-51-45604 (JP, A) JP-B-63-26171 (JP, B2) JP-B-55-35321 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name ) F27D 1/16 C21C 5/44 C21C 5/48 C21C 5/52 B22D 41/02

Claims (6)

(57) [Claims] In order to disassemble and repair part or all of a refractory lining of an electric furnace, a central part of a hearth of an electric furnace is detachable, and a demolition robot is mounted on an opening from which the central part of the hearth is removed. A mount having a floor surface that can be placed above the upper end of the opening is attached, the area of the floor is smaller than the area of the opening, and a suitable space is provided between the edge of the floor and the upper edge of the opening. Provide a gap of a wide width, place the dismantling robot on the floor of the gantry, operate the dismantling robot, dismantle the refractory lining by the mechanical force of the dismantling robot, and open the waste material of the dismantled refractory from the gap to the opening. A method for dismantling and repairing a refractory lining of an electric furnace, comprising performing a work of dropping into a container arranged below the furnace. 2. The method according to claim 1, wherein the gap is 0.6 m or more in width. 3. An electric furnace according to claim 1, wherein an operator and / or a dismantling robot entering the electric furnace are shielded from hot air remaining in the electric furnace during an initial stage of dismantling work of the refractory lining the electric furnace. A method for dismantling and repairing refractories lining a refractory by suspending a cylindrical shield from above the electric furnace and dismantling the refractories. 4. A floor according to claim 3, wherein a floor having a hole larger than said opening is attached to a bottom of said cylindrical shield.
A method for dismantling and repairing a refractory lining of an electric furnace, in which a disc-shaped scaffold is placed at the center of the hearth, and outside air is blown from above through a bellows tube inside the cylindrical shield so as to cool the workers inside. 5. The method of disassembling and repairing a refractory lining of an electric furnace according to any one of claims 1 to 4, wherein the opening is formed in a circular shape, and the container is placed on a carriage and is movable. 6. The spare hearth according to any one of claims 1 to 5, wherein a spare part of the center part of the detachable hearth is prepared separately, and a refractory lining is previously applied to the center part of the spare hearth. A method for dismantling and repairing refractories lining electric furnaces, which replaces the central part of the hearth after dismantling.