JPS5833287B2 - Gutter for molten metal - Google Patents

Description

[Detailed description of the invention] The present invention relates to a molten metal gutter such as a blast furnace tap gutter.

In recent years, large-scale blast furnace operations are expected to make significant progress today because they have a huge crude steel production capacity and are economical as the consumption of auxiliary materials related to production is relatively small.

However, with recent calls for energy and resource conservation, there is a growing demand for further reductions in the consumption of secondary materials.

It is well known that one of the above-mentioned auxiliary materials is a refractory material, and that the tap trough material occupies a very large proportion in blast furnace operation.

The corrosion damage of the refractory lining material in the blast furnace tap trough differs depending on whether it is a large trough, a middle trough, a slag trough, etc., but in the middle trough, the temperature of the hot metal is high and it also contains a large amount of slag. Its erosion is significant.

The cross section of the gutter lining material after use generally has a pattern as shown in FIG. 1 (in the figure, A indicates the line showing the melt loss after use, and B indicates the slag line).

That is, the melting loss is significant in the upper and lower stages, and it is thought that the upper stage is mainly caused by slag, and the lower stage is mainly caused by hot metal.

Research and development to deal with the above-mentioned corrosion damage is progressing at an ever-increasing rate, but the main focus is on improving the corrosion resistance of the lining material itself and developing improved construction methods.

However, these research and developments have been difficult due to economic reasons, which prevents the unit price of refractory material from increasing much, and secondly, the furnace front has to be repaired in a short period of time, which causes variations in construction accuracy and makes it difficult to achieve the desired results. High-performance fireproofing materials could not be used in the current gutter structure because they were not effective.

The reason why a water cooling structure is not used in the tap trough is because if water is used in the trough through which high-temperature hot metal passes, there is a risk of explosion if there is a leak and the water gets mixed into the molten pig iron. .

The present invention eliminates such drawbacks, reduces the erosion rate of the working lining material forming the molten metal flow path, and
This was done to improve the durability of gutters, reduce the need for fireproof materials, and ensure safe and stable operations.

That is, the present invention provides for a part or the entire surface between the working lining monolithic refractory that forms the molten metal flow path and the outer shell,
The gist of this invention is a gutter for molten metal that is characterized by being equipped with highly thermally conductive refractory bricks with built-in cooling piping.

The present invention will be explained below based on examples.

First, the present inventors analyzed the wear and tear phenomena of refractory materials caused by various high-temperature melts based on a large number of materials obtained in the laboratory and in actual furnace tests. It was concluded that for refractories with , that is, refractories resistant to simple fluid wear, the most important rate-limiting step in the wear mechanism is temperature.

For example, when the temperature rises, the refractory material constituent substances increase their solubility in the molten material in the channel, or they themselves liquefy and elute.

In addition, the reaction rate and reaction amount increase to produce a low melting point compound.

Further, phenomena such as promoting penetration of the melt into the interior of the refractory material, forming reaction products and causing structural spalling, etc., are all temperature-limited.

Therefore, we are confident that by cooling the refractory material from the outside by some means, it is possible to slow down and even stop its wear and tear.

The present invention was completed as a result of various studies based on this knowledge, and will be explained below based on an embodiment of the blast furnace tapping trough shown in FIGS. 2 to 5.

FIGS. 2a and 2b are a front view and a perspective view showing an embodiment of the present invention.

In the figure, 1 is a working lining material that serves as a flow path for molten metal, and is made of a monolithic refractory material such as stamping material, sprayed material, flow casting material, or vibration molding material, and is a purpose-built lining that is durable as a flow path. Any material may be used as long as it is a material with relatively high thermal conductivity (for example, 5 kcal/
m, hr-°C or higher) is preferable because it facilitates the expression of the cooling effect claimed by the present invention.

Table 1 shows examples of materials for working lining materials for tap troughs.

Reference numeral 2 denotes a cooling fireproof structure, which is a brick structure in which a heat medium pipe 3 for cooling such as air, steam, water, etc. is surrounded by a highly thermally conductive fireproof material 4.

The reason why this refractory material 4 is made to have high thermal conductivity is that it not only needs to exhibit sufficient cooling function, but also to deal with abnormal damage to the working lining material 1 that may occur during operation. This is because it fulfills its mission as a safety lining material.

Therefore, this refractory material 4 must be durable as a safety lining material and must be at least 10 kca# 7m.
It is particularly desirable that the material has a thermal conductivity of -hr -degC or more, and examples of such materials are shown in Table 2.

5 is a conventional safety lining material that mainly uses carbon bricks.

6 is laid with a fireproof material such as ordinary chamots or alumina to block heat transmitted from the safety lining material 5 and protect the steel skin 7.

In the embodiment shown in FIG. 2 above, the fireproof structure 2 with a built-in cooling pipe is arranged on the back side of the locally eroded part of the working lining material 1,
This is designed to balance the erosion and loss of the entire working lining material.

Figures 3 and 4 show other embodiments of the present invention, in which Figure 3 shows a structure in which a fireproof structure 2 with a built-in cooling pipe is placed over the entire back surface of the working lining material 1, thereby suppressing erosion and loss of the entire working lining material. The aim is to

FIG. 4 shows an example in which a fireproof structure 2 with a built-in cooling tube is placed on the back side of the locally eroded part of the working lining material 1, and a safety lining material 6, such as chamots brick, is placed on the outside. Even if the refractory structure with a built-in tube 2 were to be abnormally damaged, the iron skin can be prevented from being damaged.

In the present invention, by having the above-described configuration, the refractory materials 1 and 4 have high thermal conductivity and the cooling power of the cooling pipes is strong, so that the corrosion resistance of these refractory materials is significantly improved.

Furthermore, since the refractory material 4 itself is made of a material with high corrosion resistance, even if the working lining material 1 is worn out, it can withstand long-term use, and the risk of water leakage can be avoided.

Therefore, the life of the gutter can be greatly extended, safe and stable operation can be achieved, and the consumption of refractory materials can be significantly reduced.

It should be noted that the present invention is applicable not only to the tap trough but also to various types of molten metal troughs.

Example 4 In the large piglet storage trough of a 4000 m class blast furnace, 2
A gutter having the same structure as the one shown in FIG. 2 of the present invention was installed in a part including a so-called hot water contact part of ~6 m, and was used for actual operation.

Table 3 shows the materials of each refractory material used.

In addition to sending 1m3/- of water to the gutter cooling pipe,
50.50, 100°100mm from the operating surface on the side wall.
Thermocouples a, b, c, and d were embedded in the intervals to measure the temperature.

After receiving approximately 30,000 tons (40 taps) of pig iron in this manner, the left half of Fig. 5 shows the state of erosion at a point 4 m from the tap hole.

For comparison, we previously investigated the state of erosion in a conventional large trough made of a working lining material with the same composition and thermal conductivity as those listed in Table 3, at the same location and with the amount of pig iron received. Shown on the right hand side of Figure 5.

Thermocouples a and b' in this conventional gutter. The buried positions of C/ and d/ are the same as those of the embodiment of the present invention.

In the figure, C indicates the melted part. As a result, the temperature change due to the amount of pig iron received (the number of taps) on the side wall of the gutter is as shown in FIG. , c'.

A considerable difference was observed between d' and d'.

Based on the above results, when comparing the average erosion rate per iron passing amount i and ooot, in the conventional gutter, the slag part was 6.5 m and the hot pig iron part was 3.5 m, whereas in the example of the present invention, each 3.
1 mm and 2.6 mm, demonstrating that the present invention can significantly reduce gutter erosion.

[Brief explanation of drawings]

Fig. 1 is a general cross-sectional view of a blast furnace pig iron storage type large trough, and Figs. 2 to 4 are examples of the present invention, of which Fig. 2 a is a front view, b is a perspective view, and Fig. 5 6 is a comparison diagram of the melting damage cross section of the present invention and the conventional example, and FIG. 6 is a comparison diagram of the side wall temperature. 1... Working lining material, 2...
... Fireproof structure with built-in cooling pipe, 3 ... Cooling pipe, 4 ... High thermal conductivity fireproof material, 5 ... Safety lining material, 6 ... ...Insulating refractory material, 7...Iron skin.

Claims (1)

[Claims] 1. A molten metal melting system characterized in that a highly thermally conductive refractory brick with built-in cooling piping is disposed partially or entirely between the working lining monolithic refractory that forms the molten metal flow path and the outer shell. metal gutter.