JPH0484664A - Padding for sliding nozzle - Google Patents

Abstract

PURPOSE:To prevent the progression of the sintering of the nozzle padding itself and to improve the natural opening rate of a sliding nozzle by compounding a carbon black at a specific ratio into the nozzle padding. CONSTITUTION:The compounding of the carbon black into the nozzle padding is found to be extremely effective for preventing the sintering, preventing the infiltration of a molten steel and improving the characteristics necessary as the performance of the nozzle padding. The carbon black has the extremely higher residual carbon rate than the residual carbon rate of the conventional compds., such as graphite and pitch, contains the less volatile component, has the excellent characteristics to prevent the sintering and to prevent the infiltration of the molten steel. In addition, the specific surface area is large and, therefore, the dispersion effect when the carbon black is compounded into the padding is excellent and segregation is prevented. Further, the adhesiveness to silica sand, etc., is excellent. Then, the carbon black is compounded at 0.05 to 5.0wt. outer % into the nozzle padding, by which the coated state of sticking the carbon black to the circumference of the silica sand, etc., is attained. The sintering and bonding of the grains of the silica sand, etc., to each other is prevented by the carbon black of such coated state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to filling of sliding nozzles such as ladles.

(Prior art) Conventionally, the filling of a sliding nozzle used for controlling the flow rate of molten metal in a ladle, etc. is made of silica sand (90 to 99% SiO□), and is sintered by adjusting the purity of SiO□ depending on the usage conditions. (see JP-A No. 64-48662), or conversely, orthoclase (K2O・A1□03・6SiO
□) is added to cause sintering and form a viscous film on the parts that come into contact with the molten steel, thereby preventing the penetration of the molten steel.

However, in the former case, although the nozzle filling is prevented from sintering, a molten part of the filling itself is not generated, and therefore penetration of molten steel cannot be prevented.

Therefore, the natural aperture rate of the nozzle is low, and a significant improvement in the natural flowering rate cannot be expected.

On the other hand, the latter can be used satisfactorily in normal operations, but as the quality of steel increases, there are
During the high-temperature, long-term treatment lasting up to 3 hours, the nozzle filling itself is sintered to form a strong film. As a result, natural pores often did not open, and there was no significant impact on operations.

(Problem B to be solved by the invention) Therefore, attempts have been made to add scaly graphite or earthy graphite because of graphite's sintering inhibiting properties and its difficulty in getting wet with molten steel.

However, the inside of the homper and the paper bag or container before use
Due to the difference in specific gravity and the slipperiness of the graphite within the tube, segregation of the clay occurs, making it impossible to achieve the expected performance when used in actual equipment.

Further, the use of pitch or the like has been considered, but it is undesirable because it has a volatile content of 30 to 70% and generates gas during use. Furthermore, segregation also occurred.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned points, and in a nozzle filling that blocks a sliding nozzle with silica sand, MgO tarinker, zircon sand, etc., 0.05% of carbon black is added to the nozzle filling. To provide a filling for a sliding nozzle, characterized in that it contains ~5.0% by weight.

(Function) The present inventors have discovered that it is extremely effective to incorporate capon black in order to prevent sintering, prevent molten steel from entering, and improve properties necessary for the performance of nozzle clogging. In other words, carbon blank has a higher residual carbon content than conventional compounds such as graphite and pinch, has less volatile matter, has excellent properties to prevent sintering and molten steel intrusion, and has a large specific surface area, so when blended It has excellent dispersion effect and can prevent segregation.

Furthermore, it has excellent adhesion to silica sand and the like.

Therefore, by blending carbon blank in the nozzle filling with an external coverage of at least 0.05%, a coating state with carbon bra 7 adhering around the silica sand etc. is obtained, and the capon blank in various coating states is used to cover the silica sand etc. It is possible to prevent particles such as the like from sintering and bonding together. Furthermore, the property of carbon black to prevent molten steel from entering can prevent molten steel from entering the nozzle filling, thereby improving the natural porosity of the sliding nozzle. It should be noted that if the content of carbon black is less than 0.05% by weight, the effect of preventing particles from bonding with each other is insufficient, and if it exceeds 5.0% by weight, residual carbon will increase, which is not preferable.

(Example) Hereinafter, the present invention will be explained based on examples.

In the present invention, a filling for a sliding nozzle such as a ladle is formed by blending carbon black as a graphite source with silica sand whose particle size has been adjusted in an outer layer ratio of 0.05 to 5.0% by weight.

Table 1 Examples of particle sizes of silica sand Table 2 Examples of chemical composition of silica sand As examples of particle sizes of the above-mentioned silica sand, those shown in Table 1 can be used.

Further, as an example of the chemical composition of the silica sand, those having purity as shown in Table 2 can be used.

(Manufacturing example) Regarding such a nozzle filling, the composition of silica sand and carbon blank was changed in various ways as shown in Table 3 on the next page, and the nozzle filling with a diameter of 50 mm and a height of 50 mm was placed in a crucible made of zircon bricks. and baked at 1400°C for 12 hours. The results are shown at the bottom of Table 3.

Table 3 shows a comparison between a standard product containing only silica sand and a product containing silica sand mixed with pinch or earthy graphite.

As can be seen from Table 3, the sintering conditions of the present invention containing carbon black showed that the surfaces of the grains were slightly or hardly stuck to each other, and the bond was weak, resulting in good results as expected. there were.

In addition, in the manufactured product, carbon blank was coated around the silica sand grains, and no segregation of carbon was observed.

Furthermore, if the carbon black content is less than 0.05%, the effect of preventing the particles from bonding to each other is insufficient, and the carbon black content is less than 0.05%.
If it exceeds the weight percentage, residual carbon increases, which is not preferable.

Table 3: Comparison of nozzle fillers (example of use) The product No. 12 of the present invention shown in Table 3 above was used in sliding nozzles for ingot making and continuous casting. The results are shown in Table 4.

Table 4 As shown in the table of usage examples, the product of the present invention showed a good natural porosity after being used 360 to 500 times.

If the hole does not open naturally, the hole must be forcibly opened by removing the long nozzle or blowing oxygen from the bottom, which will expose the molten steel to air, adversely affecting the quality and lowering the quality. Improving the natural porosity is important for improving productivity because it causes a great deal of damage due to falling and waste material (70 tons/time).The particle size and chemical composition of the silica sand described above are limited to the examples. However, it can also be applied to other particle sizes and chemical compositions, and can be similarly applied to nozzle fillers such as magnesia chrome clinker and zircon sand.

Furthermore, the invention is not limited to adding and blending only carbon black to silica sand, etc., and scaly graphite may also be used in combination. At that time, carbon black is 0.05
It is necessary to incorporate at least 30% by weight of ~50% by weight.

The nozzle filler of the present invention can be applied to control the flow rate of molten metal in ladles, tundishes, and other molten metal containers.

(Effect of the invention) As described above, in the present invention, carbon black is
．． Since it contains 05 to 5.0% by weight, it can prevent the nozzle filling itself from sintering, improve the natural porosity of the sliding nozzle, and greatly contribute to improving steel productivity. It is.

Claims (1)

[Claims] (1) A nozzle filling for blocking a sliding nozzle with silica sand, MgO clinker, zircon sand, etc., characterized in that the nozzle filling contains 0.05 to 5.0% by weight of carbon black.