JPS6160126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a gas injection part (including a porous plug) for injecting gas, etc. into molten metal in a kiln (including a ladle, tundish, mixer car, smelting furnace, gutter, etc.). , and a method for forming the same.

The gas injection section injects gas into the molten metal to perform desulfurization, degassing, and separation of non-metallic inclusions to improve the quality of the copper. Contact, cooling of the furnace, breakage during plug replacement, etc. can lead to erosion, wear, and spalling, resulting in damage. Therefore, in order to prevent damage caused when replacing the plug, etc., a two-layer structure consisting of an outer cylindrical body and an inner cylindrical body is used, and measures such as adding hot strength are used to protect against molten steel flow, loads, and contact with the plug. Therefore, efforts are being made to adjust the material and sinter it.
In addition, in order to ensure proper plug replacement timing and to ensure safety, two sintered bricks were assembled into one porous plug, with the surface in contact with molten steel and the surface not in contact with the molten steel separated into an upper layer and a lower layer. There is something.

Each of these items has its own unique characteristics, but as they are used, they tend to become damaged and are generally replaced with new ones when they reach about half their original size.

However, the used plugs (bricks) discarded in this way are sintered products of high-grade materials such as magnesia, high alumina, and zircon.
It is not economical to discard the plug at this point, and the time required to replace the plug cannot be ignored.

The purpose of the present invention is to provide safety without requiring high hot strength, to make it inexpensive, and to prolong its life by repairing the gas injection part.
The gist of this is that the gas injection part has at least a two-stage structure consisting of an unfired refractory or monolithic refractory on the side that contacts the molten metal, and a fired or unfired refractory on the side that does not come into contact with the molten metal. It's about doing.

Note that the gas blowing part of the present invention is intended to be provided at the bottom or side wall of a kiln.

Unfired or monolithic refractory for gas injection of the present invention,
Or fired refractories (brick, monolithic refractories)
can be obtained by conventional methods, i.e., by forming permeable pores between particles by using a particle size structure using coarse particles and intermediate particles, or by heating (heating during firing or using a furnace). etc.) to align or mix metal wires, organic fibers, and particles that disappear into the refractory to form vent holes when the refractory is heated, or to open holes after the refractory hardens. say something

Here, to give an example of an unfired breathable refractory, the particle size of the aggregate is 1 mm or more (preferably 3 to 1 mm).
30-80% (preferably 60-80%) of 1mm or less (preferably 1-0.2mm), 20-70% (preferably 20-40%) of 1mm or less (preferably 1-0.2mm), or all 1mm
The particle size structure is as follows, and the material is one or more of magnesia, magnesia chromium, corundum, mullite, zircon, zirconia, carbon, and clay. As the binder, phenolic resin, alumina cement, phosphate, bittern, alumina sol, metal silicon, Al powder, etc. are selected, and the material is dried at 150 to 800°C for 3 to 8 hours.

Next, the present invention will be specifically explained with reference to the accompanying drawings (FIGS. 1 to 7).

First Embodiment (Fig. 1) Fig. 1 shows a case where the gas injection part according to the present invention is formed of a brick-like refractory, and 1 in the figure shows the gas injection brick provided at the bottom of the ladle. Receiving part, 2
3 is an iron shell, 3 is a porous plug, and 4 is joint mortar for fixing the porous plug 3 to the gas-injected brick receiver 1. Also porous plug 3
consists of an upper plug 3a made of an unfired refractory brick or monolithic refractory having a molten metal contact surface on the upper surface, and a lower plug 3b made of a fired or unfired refractory brick having a molten metal non-contact surface on the lower surface.

As a method for forming a gas blowing section having such a configuration, the upper plug 3a and the lower plug 3b are assembled integrally in advance to form the porous plug 3, and the porous plug is filled with joint mortar 4.
The upper plug 3a and the lower plug 3b may be attached to the gas injection brick receiving part 1 separately and in sequence.

When setting in a kiln, it may be set from outside the furnace or from inside the furnace. The space between the permeable refractory on the molten metal contact surface and/or the outer lining of the permeable refractory on the non-molten metal contact surface is filled with non-porous or low permeable monolithic refractory such as mortar. Obstruction.

Second Embodiment (Figure 2) Figure 2 shows a gas injection part according to the present invention, particularly from an unfired breathable refractory or monolithic refractory having a molten metal contact surface (hereinafter referred to as breathable monolithic refractory). This shows the case where the upper plug 3a is formed. In this case, when forming the gas injection part in the furnace, after setting the lower plug 3b, which has a non-contact surface to molten metal and is made of a breathable refractory material, into the furnace, the gas injection part is inserted into the furnace from the inside or outside of the furnace. A shaped refractory is filled by pouring, press-fitting, stamping, spraying, thermal spraying, etc. to form the upper plug 3a.

Furthermore, the formation of the gas blowing hole section using the breathable monolithic refractory is generally considered to be for the case of new installation of the gas blowing section or for the case of repair (hot or cold).

In the case of hot repair, pickle the damaged part of the gas injection part and its surroundings as shown in Figure 3 A to D. ), after removing the base metal and slag 6, it is preferable to form an unburnable refractory or a thermally sprayed refractory layer having a gas injection hole filled with an air-permeable monolithic refractory into the resulting space. The pickling can also be carried out by blowing oxygen through the inert gas introduction pipe 7.

The above repair mode can also be applied to the first embodiment, and in this case, as shown in FIG.
Insert a breathable unfired brick 3a into the cleaned space, place it on the side that is close to the molten metal contact surface of the refractory on the non-molten metal contact surface side, and place mortar between this breathable brick and the surrounding lining. 4a etc. and fixing the bricks to form a gas injection part.

Furthermore, in the case of repair, the initial gas blowing section may not be two-staged from the beginning as described above, but may instead be a normal single-stage gas blowing section. In this case, the undamaged remaining part of the single-stage type (on the non-molten metal contact side) becomes the second stage, and the breathable monolithic refractory filled closely with it on the non-molten metal contact side becomes the first stage. . (See Figure 5 A to D). In addition, in the case of a kiln with a gas injection part on the side wall or a furnace with a gas injection part on the bottom, which is to be set with the bottom vertically placed, the air-permeable monolithic refractories and joints are required. Abut the board frame to prevent the mortar from falling.

Other embodiments (modifications) of the gas blowing part and the method of forming the same according to the present invention will be described below.

(a) When the air-permeable unfired refractory or monolithic refractory on the molten metal contact surface side of the present invention is in a state where molten metal is contained, due to the difference in specific gravity, the air-permeable unfired refractory or monolithic refractory is As shown in Figures 7 and 8, unevenness 8 is added to the air-permeable refractory on the molten metal contact surface (even in the case of fired bricks) and/or the surrounding lining and/or the air-permeable refractory on the side that does not come into contact with the molten metal. Measure to prevent floating by adding a taper 9.

(b) The refractory layer on the molten metal contact surface side and the molten metal non-contact surface side is preferably parallel to the inner surface of the surrounding lining furnace, but the thickness of the layer is not limited to this.
Repairs are determined in accordance with the furnace operating conditions, and the repair conditions are also taken into account.

In general, a range of 1/4 to 2/4 is desirable. The number of layers is not limited to two, but may be any desired multilayer.

(c) The part of the outer periphery of the gas injection part that comes into contact with the gas injection brick receiving part 1 or the gas injection brick receiving part is made of conventional unfired or fired refractory material, and the gas injection part is connected so that it can be taken out to the outside or inside of the furnace. Surrounding outer peripheral layers 3a-1 and 3b-1 may be formed. (See FIG. 8) In this case, the gas-blown brick receiving part 1 is less damaged and can be replaced quickly, which further adds to the features of the present invention.

(d) The materials for the breathable refractory on the molten metal contact side and the breathable refractory on the non-molten metal contact side are acidic, neutral, and basic refractories. or,
By making the composition contain carbon, its durability can be improved, and it is also suitable for pickling during repairs and removing metal and slag using combustion gas, etc. In other words, it is quick and easy to burn out the carbon it contains. It can also be cleaned cleanly, allowing the replacement molten metal contact side permeable refractory to be applied to the molten metal non-contact side permeable refractory in the pickling space without passing through metal, slag, or refractory debris. The same applies when a brick-shaped material is used as the air-permeable refractory on the side that contacts the molten metal.In this case, the mortar filled between the gas-blown brick receiver and the air-permeable brick also can be filled without leaving any of the impurities mentioned above.
Therefore, the air-permeable refractory and mortar can be firmly filled, and new installations and repairs can be performed satisfactorily.

(e) In particular, a carbon-containing refractory is used as the permeable refractory on the molten metal contact side, while a carbon-free refractory is used as the permeable refractory on the non-molten metal contact side, or a combination of both. This would be very advantageous when repairing molten metal contact surface permeable refractories. That is, the remaining carbon-containing molten metal contact surface air-permeable refractory is blown off by pickling, and unnecessary materials can be easily, quickly, and reliably removed.

In this case, the carbon-containing breathable refractory includes both bricks and monolithic refractories, and in the case of bricks, there is
Preferably, it is filled with a carbon-containing joint filler. Further, as the joint material between the molten metal non-contact surface permeable refractory and the gas-injected brick receiver, it is more convenient to use a refractory that does not contain carbon because it will not be corroded during pickling.
However, when replacing a molten metal non-contact surface permeable refractory, it is easier to remove using a carbon-containing joint filler.

(f) Molten metal contact surface When using breathable refractories in the form of bricks, the degree of permeability can be controlled to a certain extent or reliably, but when using them as monolithic refractories, they cannot be placed in a furnace such as a pot. Since it is filled and formed by direct pouring, stamping, press-fitting, spraying, thermal spraying, etc., it may not be possible to do the work in detail, but in this case, the desired breathability may not be obtained. Furthermore, even the method itself for imparting breathability may not reliably provide the desired properties. In such a case, the permeability of the molten metal contact surface permeable refractory may be set higher than that of the molten metal non-contact surface permeable refractory. That is,
Air permeability is controlled by the molten metal non-contacting permeable refractory, the molten metal contacting permeable refractory is only for protection, and the gas has no resistance when passing through the molten metal contacting permeable refractory. Since it is small, it can easily pass through and effectively prevent the refractory from floating up. Note that the range in which the degree of air permeability of the molten metal contact surface is increased may be set in advance so that the air permeability may vary somewhat.

(g) When forming a direct gas injection part in the furnace, it is of course possible to form the gas injection part as an unfired integral part without dividing it into two stages, one on the molten metal contact side and the other on the non-molten metal contact side. It is.

(h) Can also be applied to sliding gas blowing parts.

As described above, the gas blowing part and the method for forming the same according to the present invention have the following effects.

1. By making sure that the molten metal contact surface side is unfired and having at least a two-stage structure with the molten metal non-contact surface side, (a) Since the second stage is in contact with the molten metal in a standby state,
By making the first stage unfired to increase spalling resistance and durability, there is no need to use a refractory with high hot strength, that is, a fired product or a high-grade material, making it economical.

(b) Even if the first stage is destroyed, it will stop at the joint between the first and second stages and will not be transmitted to the second stage, so it is safe.

(c) When using the first stage as a replacement, it will be more economical if the allowable damage limit of the gas injection part is adjusted to the volume of the first stage.

(d) The first stage can be easily dismantled, making it possible to repair the gas injection section and reducing costs.

(E) By ensuring that the molten metal contact surface side is unfired and has at least a two-stage structure with the molten metal non-contact surface side, a gas blowing part with an accurate shape can be manufactured at low cost and quickly.

2. By making the first stage unfired and the second stage made of fired bricks, the gas injection part can be manufactured economically and can be easily repaired.

3. By making the first stage a monolithic refractory, which can be cast directly onto the furnace body, (a) the brick forming process can be omitted.

(b) Even complex shapes can be created.

(c) The combination of the first stage and the second stage becomes easy.

(d) During furnace operation, when the furnace is empty, it can be repaired by filling it with monolithic refractories.

(e) Drying can be performed using the heat retained in the furnace.

4 By using a two-stage refractory and using carbon-containing refractories, replacement can be facilitated and the service life can be extended.

5. By using a carbon-containing refractory for the first stage and a carbon-free refractory for the second stage, (a) pickling can be carried out well and repairs can be carried out well.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional front view of a gas injection part according to the present invention made of a brick-like refractory, Fig. 2 is a cross-sectional front view of a gas injection part made of a monolithic refractory, and Figs. d is an explanatory diagram of a method of forming a monolithic refractory, FIG. 4 is a cross-sectional front view of another embodiment of a gas injection section formed of a brick-like refractory, and FIGS. 6 and 7 are cross-sectional front views of a gas blowing part having a floating prevention function, and FIG. 8 is a cross-sectional front view of a gas blowing part having an outer peripheral layer.

Claims (1)

[Scope of Claims] 1. In a kiln having a gas injection part, the gas injection part is a fired or unfired ventilated refractory having a molten metal contact surface or a monolithic refractory and a molten metal non-contact surface. Gas injection part structure made of durable refractory material. 2. A method for forming a gas injection part in a kiln having a gas injection part, by filling the space or damaged part of the gas injection part with an unfired or amorphous breathable refractory when molten metal is not in the furnace.