JPH0532511Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a brickwork structure for the inner wall of a molten slag heating furnace used for processing molten slag for purposes such as rock wool production.

[Conventional technology]

A method of manufacturing rock wool that reduces energy consumption by charging molten slag, which is generated in large quantities from a blast furnace, in a molten state into a heating furnace such as an electric furnace is attracting attention (Japanese Patent Application Laid-open No. 189282/1983, (Refer to Japanese Patent Application Laid-open No. 189284/1984).

FIG. 2 shows an electric furnace proposed by the present inventors in Japanese Patent Application No. 1983-291691 as an apparatus used for producing this rock wool.

Molten slag discharged from a blast furnace or the like is transported and injected into a molten slag insertion device 2 provided in the main body of an electric furnace 1 using a transport means such as a pan car 3. Then, by adjusting the stopper 4, an appropriate amount of molten slag is charged into the electric furnace 1 from the molten slag charging device 2. The molten slag charged into the electric furnace 1 is stirred by the inert gas blown from the gas introduction pipe 6 together with the component adjusting agent such as preheated silica stone charged through the charging pipe 5. . Further, an electrode 7 is inserted into the electric furnace 1 as a heating means so that the molten slag in the furnace is maintained at a predetermined temperature.

The molten raw material 8 heated and component-adjusted in the electric furnace 1 is discharged from the outlet 10 to the cotton mill 11 by tilting the electric furnace 1 by driving a tilting mechanism 9 such as a fluid cylinder. On the other hand, hot metal contained in the charged molten slag is separated from the molten slag in the furnace and deposited on the bottom of the furnace. This hot metal 12 is discharged from the tap hole 13 by appropriately tilting the electric furnace 1 in reverse. In addition, the code number 14 indicates this taphole 1.
3 is shown.

[Problem that the invention attempts to solve]

The inner walls of this molten slag heating furnace are constructed of graphite bricks that have excellent slag erosion resistance because they come into contact with molten slag. The inside of the furnace is maintained in a reducing or inert atmosphere to prevent oxidation of the graphite bricks during operation. However, in this type of heating furnace, in order to equip the molten slag charging device 2, auxiliary raw material charging pipe 5, gas introduction pipe 6, electrode 7, etc. on the upper part of the furnace body, a large number of them are mounted on the ceiling. An opening is provided. Furthermore, in addition to this, it may be necessary to provide the furnace lid with an exhaust port for guiding exhaust gas out of the furnace, a manhole for inspecting the inside of the furnace, a hole for monitoring the inside of the furnace, and the like.

Therefore, it is inevitable that outside air will enter through the opening in the furnace lid. Furthermore, when performing periodic internal inspections under high temperatures inside the furnace, measuring the amount of brick erosion, sampling molten material, etc., it is extremely difficult to operate under positive pressure while maintaining an inert atmosphere inside the furnace. . Furthermore, after continued operation for a certain period of time, all of the molten slag and hot metal in the furnace were discharged, the water-cooled copper nozzle at the outlet was replaced, the corrosion state of the furnace bottom brick directly below the electrode was investigated, and the taphole area was investigated. Work such as replacing bricks is required, but it is not possible to completely prevent outside air from entering during such work.

In addition, during the reaction process of refining molten slag, oxidizing gases such as oxygen and carbon dioxide are generated. Graphite bricks are oxidized by carbon gas and become easily corroded by slag. Such oxidation is particularly noticeable on the inner wall of the molten slag in contact with the molten metal surface.

Therefore, an object of the present invention is to provide a durable molten slag heating furnace that prevents oxidation and slag erosion.

[Means for solving problems]

In order to achieve this purpose, the brickwork structure of the present invention maintains the inside of the furnace in an inert atmosphere, and homogenizes the molten slag by maintaining it at a high temperature while adding auxiliary materials. In a molten slag heating furnace that continuously discharges a certain amount of material, the upper part of the furnace and the inner wall near the molten metal surface are constructed of silicon carbide bricks.
It is characterized in that the inner wall below the vicinity of the hot water level is constructed of graphite bricks.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

The molten slag heating furnace has a molten slag surface 8 in the furnace.
In order to carry out the treatment while maintaining a constant, when the amount of molten slag in the furnace becomes low, molten slag is charged while tilting the heating furnace. Moreover, when discharging the treated molten slag, the heating 1 is tilted to the right in FIG. On the other hand, when discharging the hot metal separated from the molten slag, the heating furnace 1 is tilted to the left.

In this way, the molten slag surface 8a moves vertically along the inner wall over a wide range. Therefore, in this embodiment, as shown in FIG. 1, the inner wall above the lowest position 8b of the molten slag surface 8a is constructed of silicon carbide bricks A. As this silicon carbide brick A, for example, 35 to 60% by weight of silicon carbide,
Artificial graphite 20-35% by weight, metallic silicon 3-13% by weight,
The composition of roasted anthracite 0 to 35% by weight is used.

This silicon carbide brick A has excellent oxidation resistance and is unlikely to deteriorate due to oxidation even if the atmosphere in the furnace contains some oxidizing gas such as oxygen. It also has sufficient resistance to erosion by slag.

However, if the entire inner wall is constructed with silicon carbide bricks A, the heat of the molten slag will be transferred to the outside, especially near the outlet 10 and the tap hole 13, where the furnace wall is thin, due to its relatively high thermal conductivity. It will be dissipated. Therefore, the fluidity of the molten slag and hot metal decreases as the temperature decreases, making the tapping state unstable. In order to compensate for this drawback, in this example,
The vicinity of the outlet 10 and the tap hole 13 is constructed of graphite brick B, which has a relatively low thermal conductivity.

Furthermore, if graphite bricks are placed only in the vicinity of the outlet 10 and the tap hole 13, a difference in thermal expansion will occur between the graphite bricks and the silicon carbide bricks at the locations where they are in contact with the silicon carbide bricks.
As a result, the vertical joints of the bricks are cut, causing problems such as molten slag, hot metal, etc. entering the joints. Therefore, graphite bricks B are used to construct the entire inner wall below the lowest point 8b of the hot water level. Moreover, when constructing in this manner, the cost of constructing the furnace is reduced compared to the case where the entire inner wall of the furnace is constructed from silicon carbide bricks.

As this graphite brick B, for example, one having the following composition or composition is used.

Composition Composition Roasted anthracite 90-80% by weight 80-85% by weight Natural graphite - 7-10% by weight Artificial graphite 10-20% by weight - Alumina powder - 4-5% by weight Silicon metal powder - 4-5% by weight This graphite Plain bricks have inferior oxidation resistance compared to silicon carbide bricks, but in the unoxidized state they exhibit excellent resistance to erosion by slag.
In addition, since the thermal conductivity is lower than that of silicon carbide bricks, if this brick is used in the inner wall portion with a small wall thickness, especially near the outlet 10 and the tap hole 13, the heat of the molten slag will be transferred through the inner wall. The rate of radiation is also reduced. Furthermore, this graphite brick exhibits sufficient resistance to hot metal. Therefore, there is almost no deterioration due to molten pig iron separated from the molten slag charged into the furnace and deposited on the bottom of the furnace.

Thus, by combining silicon carbide bricks A and graphite bricks B as refractories used for the inner wall of the heating furnace, a molten slag heating furnace with excellent durability and high thermal efficiency can be obtained.

For example, in an electric furnace where the height inside the furnace is 1300 mm, the normal height of the molten slag surface 8a is 750 mm, and the distance from the bottom of the furnace to the lowest point 8b of the molten metal surface is 500 mm, the inner wall above the lowest point 8b of the molten metal surface was constructed from silicon carbide bricks A, and the inner wall below it was constructed from graphite bricks B, which are the same material used for electrodes in electric furnaces. However, silicon carbide brick A
and graphite brick B had the following compositions.

Silicon carbide brick A Graphite brick B Roasted anthracite 30% by weight Roasted anthracite 90% by weight Silicon carbide 40% by weight Artificial graphite 10% by weight Artificial graphite 25% by weight Silicon metal 5% by weight As shown above, it is composed of two types of bricks. After using the electric furnace with the inner wall for 4,000 hours, we inspected the damage on the inner wall and found that the silicon carbide brick A in the area where the molten slag surface moves is 40 mm
It was only eroded to a depth of .

In contrast, in an electric furnace whose entire inner wall was constructed of graphite bricks, the damage depth was 160 mm under the same conditions.

[Effect of idea]

As explained above, in the present invention, the inner wall of the molten slag heating furnace is divided into upper and lower parts from the lowest level of the molten metal, with the upper part made of silicon carbide bricks and the lower part made of graphite bricks. are doing. Thereby, excellent properties such as slag erosion resistance and hot metal resistance can be fully exhibited without causing deterioration of graphite bricks due to oxidation. Since the heating furnace constructed in this manner has excellent durability, the number of repairs can be reduced, and its operating efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 shows the internal structure of a molten slag heating furnace to which the present invention is applied. Further, FIG. 2 is a diagram showing a molten slag heating furnace disclosed in the specification of Japanese Patent Application No. 1983-291691 filed by the inventors of the present invention.

Claims (1)

[Scope of utility model registration request] In a molten slag heating furnace, the inside of the furnace is maintained in an inert atmosphere, the molten slag is homogenized by maintaining it at a high temperature while adding auxiliary materials, and then a certain amount of the obtained molten material is continuously discharged. 1. A brickwork structure for a molten slag heating furnace, characterized in that an inner wall in the upper part of the furnace and near the hot water level is made of silicon carbide bricks, and an inner wall below the hot water level is made of graphite bricks.