JPS6030570A - Pan for molten steel - Google Patents

Abstract

PURPOSE:To extend the life of a pan for a molten steel with decreased heat loss and limited spalling by consisting an internal lining layer of neutral or acidic refractories and sticking specific basic refractories having a specific thickness on the surface therof thereby maintaining the basic characteristic of the furnace wall. CONSTITUTION:An internal lining layer 2 of a pan for a molten steel is formed of neutral or acidic refractories and basic castable refractories having about 10-25mm. thickness are stuck to the inside wall surface thereof. Basic refractories are best preferred as the pan wall to withstand high temp. and to improve the cleanliness of the molten steel but are inferior to neutral or acidic refractories in terms of heat conductivity, coefft. of thermal expansion, density and specific heat and are liable to cause structural spalling during use. The inside of the wall is formed of the neutral or acidic refractories to overcome such disadvantage and to limit the surface spalling thus permitting easy repair. The slag line 5 in the upper part of the wall is more preferably made of all basic refractories.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a basic monolithic refractory used for molten steel ladle.

Recently, the usage conditions for molten steel ladle lining refractories are becoming more severe due to increased molten steel degassing treatment ratio, high temperature tapping, extended residence time, etc. Furthermore, demands for improving the cleanliness of molten steel quality are also increasing. There is. 1. Refractories that meet these conditions
One example is basic refractories.

Basic refractories generally have higher coefficients of thermal expansion, thermal conductivity, density, and specific heat than neutral or acidic refractories, and are more likely to cause structural spalls during use. Therefore, in order to use basic refractories as lining refractories for molten steel ladle, it is necessary to strengthen preheating and heat retention management, it is necessary to strengthen insulation to reduce the drop in molten steel temperature, and the weight of the ladle increases. To increase the lifting load capacity of traditional overhead cranes or
It is necessary to take measures such as reducing the amount of steel received, structural spalls occur during use, metal intrusion into cracks, metal and slag adhesion to the inner surface of the lining, etc., resulting in a reduction in pot volume.
In addition, problems such as difficulty in determining the lifespan have occurred.

The present invention was developed based on the results of various tests in order to solve the problems during use caused by the characteristics of basic refractories and to apply basic refractories as lining refractories for molten steel ladle. In this case, the lining layer is mainly composed of a neutral or acidic refractory, and the inner surface of the side wall of the neutral or acidic refractory part is 10 to 25. The reason is that the entire surface is covered with basic monolithic refractory material with a thickness of rnm.

The details of the present invention will be described below with reference to the illustrated examples of FIGS. 1 to 6. In Figure 1, 1 is a basic monolithic refractory and 2
It is coated on the inner surface of a neutral or acid-lined refractory. Methods for coating this basic monolithic refractory 1 include spraying, troweling, and pouring, but as described below, in the present invention, the basic monolithic refractory 1 is coated with a thickness of 10 to 25 m.
The purpose is to apply a thin coating with a thickness of m, and the spraying method or troweling method has better workability than the pouring method, but any construction method can be applied and is not particularly limited.

A permanent refractory 6 is a neutral or acidic refractory, and is installed inside the steel shell 4. In addition, as shown in FIG. 2, when a basic refractory is used in the slag line part 5, it is not necessary to cover the basic monolithic refractory 1 in that part, and as shown in FIG. As such, the base portion 6 does not necessarily need to be coated with the basic monolithic refractory 1. The surface to be covered can be selected based on the cleanliness of the molten steel quality and the cost of the refractory, but at least the area where the neutral or acidic lining refractory of the side wall is to be used should be entirely covered.

In addition, as shown in FIG. 4, if the thickness of the basic monolithic refractory 1 is less than 1r3 mm, the temperature at the interface with the neutral or acidic lining refractory 2 increases during steel receiving.
Basic monolithic refractory 1 and neutral or acidic lining refractory 2
This is not preferable because it causes a contact reaction and is likely to peel off from the boundary.

On the other hand, if the coating is applied to a thickness of 25 mm or more, cracks will occur in the coating layer parallel to the operating surface and peeling will occur, which is not preferable. The reason for this peeling is thought to be that the physical properties of the permeated layer changed significantly due to the penetration of slag components, causing structural spalls.

The coating thickness of the basic monolithic refractory 1 is 1D to 25 according to the present invention
Even in the case of a thickness of mm, the slag component penetrates, but peeling of the coating layer occurs only in very rare cases. If peeling occurs, repair the peeled part using hot spraying methods.

The basic monolithic refractory 1 will also be damaged by erosion if the number of times it is subjected to steel increases, but in that case, it is preferable to repair the coating with the basic monolithic refractory 1 and maintain the overall thickness of the coating layer at about 10 to 25 mm.

As mentioned above, the molten steel ladle ζ according to the present invention does not require reinforcement of preheating or heat retention management, the drop in molten steel temperature is small, the weight of the ladle hardly increases, and there is almost no structural spall during use. It has many advantages, such as the ease of determining the lifespan since it does not occur often.

Next, examples according to the present invention will be shown.

A refractory was constructed as shown in Table 1 for a molten steel ladle having a capacity of 500 tons in the manner shown in FIG.

Table 1 Table 2 shows a comparison between the molten steel ladle according to the present invention and a conventional mesh using basic refractories for the lining layer. Basic steel can be obtained.

In addition, as an example of basic monolithic refractory 1 in Table 2, [MgO
system, MgO-CaO system, MgO-A #203
There are various systems, etc., and there is a slight difference in lifespan, but it can be selected arbitrarily based on molten steel cleanliness, lifespan, cost, etc., and there are no particular restrictions.
No.

[Brief explanation of drawings]

1 to 3 are longitudinal cross-sectional views of a molten steel ladle showing examples of the present invention, and FIG. 4 is an example of measurement results showing the relationship between the thickness of the colored layer and the peeled area ratio. 1 Basic monolithic refractory 2 Neutral or acidic lining refractory 3 Permanent refractory 4 Iron skin 5 Basic refractory 6 Laying part 1st rod 2nd 3rd figure 4-Figure 1O2θ 30 #, 5θ Thickness of board covering scrap)

Claims (1)

[Claims] The lining layer is mainly composed of neutral or acidic refractories,
A molten steel ladle characterized in that the inner surface of the side wall of the neutral or acidic refractory portion is entirely covered with a basic monolithic refractory having a thickness of 10 to 25 mm.