JPH0452072A - Method for preventing air leakage in refractory for slide gate - Google Patents

Abstract

PURPOSE:To prevent air leakage from cracked part developed at dowel part in a slide plate of a slide gate or a nozzle by applying coating material for preventing air leakage having specific softening temp. at the dowel part of plate brick in the slide gate or on outer peripheral surface of the nozzle brick. CONSTITUTION:In the outer peripheral surface of dowel part 1' in the slide plate 1, the coating material 10 is applied on exposed part. The coating material for preventing air leakage uses the one of composition having the property softening at 300-800 deg.C. (1) The air leakage from S.G. brick can be perfectly prevented. (2) Brick work is simple and the working cost is low. (3) The coating material composition is mixed material having components easy to obtain. (4) The service life of S.G. brick can be drastically prolonged. (5) By this method, the product having uniform quality without influencing to quality of the product steel, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing air leaks from cracks generated in slide plate dowels or nozzles of slide gates (S, G).

[Conventional technology]

Conventionally, the plate bricks and Nords bricks used in S and G equipment have an iron skin-wrapped structure on their outer peripheral surfaces to restrain the thermal expansion of these bricks and to suppress the occurrence and spread of cracks. In particular, measures such as covering the outer peripheral surface of the dowel portion with an iron cap as a plate have been used.

[Problem to be solved by the invention] When air enters the molten steel flow hole, it reacts with the molten steel and produces Fe.
It is known that these oxides react with alumina and mullite in brick aggregate to produce low melting point compounds, and as a result, the bricks are eroded. In addition, in carbon-containing bricks, the carbon is oxidized, which deteriorates the structure and strength of the brick and increases damage.Furthermore, the product steel ingot contains non-metallic inclusions, which affects the quality of the steel ingot. It is also known to have negative effects.

It is also known that these conventional methods have the following deficiencies: (1) Dimensional variations in the steel shell and bricks used cause variations in the restraining force and unbalanced loads; The use of this may cause the iron shell or the cap to shift, making the desired effect insufficient.

(2) In particular, the dowel portion has an "R" shape, which tends to lead to unstable adhesion to the cap.

(3) The use of the cap increases the manufacturing cost and the cost required for setting it on the dowel portion.

[Means to solve the problem]

The present inventors have developed the air leak prevention method of the present invention as a result of various studies and experiments in order to improve the various drawbacks of the conventional method as described above. As specified in the range, even if cracks occur on the outer peripheral surface of the S and G plate bricks or nozzle bricks, which soften at the S and G operating temperatures and allow air to enter from the brick body, as well as cracks, these cracks will not be removed. Air leaks are prevented by applying an air leak prevention coating agent that has a sealing effect.

The temperature of the molten steel flowing down the S and G molten steel distribution holes is usually 1550.
~1600℃, and the external surface temperature of the metal case of S and G equipment or exposed parts not covered with brick cushioning material or iron skin, such as dowels, is 500~1000℃ (depending on the thickness and material of the dowel) There are differences in temperature range).

Therefore, the air leak prevention coating agent used in the present invention is 3
Compositions having the property of softening at 00 to 800°C are used, and representative examples thereof are listed in Table 1: A plate brick is usually used in a half-drawn state. In this case, the molten steel flows down inside the flow hole unevenly, and at that time, negative pressure (
0.5 atm) area, and this negative pressure causes atmospheric air to be sucked through cracks, etc. However, by applying a softened coating material as in the method of the present invention, atmospheric suction can be prevented. can be prevented.

The method of the present invention is applied to the outer peripheral surface of a plate brick dowel or a nozzle, and a specific example thereof is illustrated in FIGS. 1 and 2.

FIG. 1 is a longitudinal sectional view of an example in which the present invention is applied to a two-type S and G device, where S and G are known mechanisms, and the outer peripheral surface of the dowel portion (1') of the slide plate (1). This is an example in which the coating agent (10) is applied to the exposed portion.

Similarly, Fig. 2 is a longitudinal sectional view showing an example applied to the three types S and G devices, and in these S and G, seal plate) (2)
This is an example in which the coating agent (10) is applied to the outer circumferential surface of the dowel portion (2') and the lower outer circumferential surface of the chute nozzle (3).

Note that the outer circumferential surface refers to the outer circumferential surface that is not sealed by the supporting members or cushioning materials of the S and G devices and is exposed to the atmosphere.

Example Table 1: S and G coated with coating agent C as shown in Figures 1 and 2.
When molten steel was injected using the device, no air leakage from the cracks was observed.With the conventional method, local damage occurred due to air leakage from the cracks after one charge, and the bricks had to be replaced, but after three charges, the bricks were replaced. It was found that the service life of S and G bricks can be significantly extended, and that there is no adverse effect on the quality of the product steel.

〔Effect of the invention〕

(1) Air leaks from S and G bricks can be completely prevented.

(2) Construction is easy and construction costs are low.

(3) The coating composition is also a mixture of readily available components.

(4) The life of S and G bricks can be significantly extended.

(5) Products of uniform quality can be obtained without affecting the product steel quality.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view when the air leak prevention method of the present invention is applied to two-layer structures S and G, and Fig. 2 is a longitudinal sectional view when it is applied to three-layer structures S and G. In the figure: ■... Slide plate, 1'...Dowel part, 2...
・Seal plate, 2'... Dowel part, 3... Shoot nozzle, IO... Coating agent. Figure 1

Claims (1)

[Claims] A method for preventing air leaks in refractories for slide gates, comprising applying an air leak prevention coating agent having a softening temperature of 300 to 800° C. to the outer peripheral surface of plate brick dowels or nozzle bricks of the slide gate.