JP3202811B2 - Molding method for sleeve-like refractories of containers for handling molten metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a lower nozzle such as a ladle or tundish for continuous casting, a long nozzle connected to the nozzle, a dipping nozzle, or a container for handling molten metal such as a converter or a ladle. steel outlet sleeve, to forming shape methods sleeve-shaped refractories used for the tuyere and the like.

[0002]

BACKGROUND] as the null form method of this kind sleeve refractory,
Sometimes method of integrating a plurality of refractories and formed shape in a ring shape are connected by mortar is used, the sleeve-like refractory obtained by this method, mortar mortar from the poor corrosion resistance The joint is easy to melt locally,
There is a disadvantage that the service life is shortened. So usually, a method of obtaining a sleeve-shaped refractory structure without joints and formed shape in one piece in the longitudinal direction is adopted.

[0003] For forming the shape methods longitudinally sleeve-shaped refractories and formed shape in one piece, covering the cylindrical mold core rod mold concentrically, by blending the binder into molds kneading After filling the the material, made of rubber piece method tamped by the impact force by dropping a weight from above, a method of forming shape by applying a pressure by a press to the material filled in the molds, the core rod mold filling the material in the frame is covered with a cylindrical frame, immersed in oil or water after covered gold lid and formed shapes to increase the pressure of oil or water, so-called CIP (ColdIsostatic
Press) formed form method and the like are known.

[0004]

[SUMMARY OF THE INVENTION] or tamped with an impact force to the axial direction, in the case of two-party method prior to forming shape by applying a pressure by a press, the fluctuation in the denseness of the material in the longitudinal direction while easy to appear, in the latter CIP forming shapes method of forming shape by applying pressure from the isotropic in water or in oil, has the advantage of easy uniform structure is obtained, in the axial direction formed
As compared with the forming method, there is a problem in that the material is inferior in denseness and porosity is high, hot strength is reduced and corrosion resistance is inferior.

[0005] These problems are conventional by CIP forming form method,
It believed to have resulted from the fact that the restrictions on the equipment not be increased water pressure or hydraulic pressure at the time of forming shape, formed in the size of the equipment
It has been considered that the solution can be solved by increasing the water pressure or the hydraulic pressure at the time of shaping , and that the higher the pressure, the higher the density of the material and the lower the porosity. However, according to the experiments of the present inventors, there is a peak pressure in the improvement of the durability, and when the peak pressure is exceeded, the durability deteriorates conversely, and an optimum pressure exists in the improvement of the durability. I found to do.

[0006]

The present invention has been made on the basis of the above-mentioned findings, and contains 70 to 95% by weight of magnesia,
Of molten metal container containing 5 to 25% by weight of molten metal
A) A sleeve-shaped refractory containing 1.8 was formed using the CIP molding method.
It is characterized by being molded at a pressure of .about.2.5 t / cm ² .

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention as described above, that where the pressure of the CIP forming shape Method and 1.8~2.5t / cm ^2, the pressure 1.8t
If it is lower than / cm ² , the filling property of the material is deteriorated and a dense structure cannot be obtained, and if it exceeds 2.5 t / cm ² ,
Internal cracks occur and the structure becomes degraded.

[0008]

EXAMPLE 1 In a sleeve refractory for a tap hole of a converter, 80% by weight of fused magnesia, 17% by weight of natural graphite, 3% by weight of an Al-Mg alloy and 3% by weight of a liquid phenolic binder. kneading this by adding, pressure 2 by CIP forming shape method.
After heating formed form at 0t / cm ^2, dried for 24 hours at 90 ° C., the inner diameter then 10 hours cured at 250 ° C. 145
An evaluation sample of a sleeve-like refractory having a diameter of φ, an outer diameter of 335 mm, and a length of 1600 mm was obtained. Then, an apparent specific gravity, a bulk specific gravity, an apparent porosity, a hot bending strength at 1400 ° C. , corrosion resistance, and an evaluation sample of Comparative Example 1 obtained in the same manner as described above except that the pressure was 1.6 t / cm ² were used. The service life in the actual furnace was compared. As a result, as shown in Table 1, in Example 1, the apparent specific gravity was increased by 0.01, the bulk specific gravity was improved by 0.05, and the apparent porosity was reduced by 1.5% as compared with Comparative Example 1. And 1400
The hot bending strength at ℃ was improved by 0.7 MPa.

The erosion index of Comparative Example 1 as 100 was 8
6. The service life index of the actual furnace was 110, the structure was dense, high hot strength and high corrosion resistance were exhibited, and the service life in the real furnace was improved. Here, in the erosion test, a high frequency induction furnace lining method was used, and electrolytic iron and slag (CaO / SiO ₂ = 3.3) were used.
(18% of total Fe) was heated at 1700 ° C. for 4 hours, and the degree of erosion of the sample was indicated by an index. The smaller the index, the better the corrosion resistance.

[0010] EXAMPLE 2 formed form pressure, except that the 2.5 t / cm ^2, the evaluation samples obtained in the same manner as in Example 1, the formed shape pressure 2.7
Comparative Example 2 obtained in the same manner as in Example 1 except that t / cm ² was used.
Evaluation sample, apparent specific gravity, bulk specific gravity, apparent porosity, 1
The hot bending strength at 400 ° C., the corrosion resistance, and the service life in an actual furnace were compared. As a result, as shown in Table 1, Example 2 has the same apparent specific gravity, the bulk specific gravity is improved by 0.02, and the apparent porosity is reduced by 0.9%, as compared with Comparative Example 2. The hot bending strength at 1400 ° C. was improved by 0.6 MPa. The erosion index when Comparative Example 1 was set to 100 was 103 in Comparative Example 2, whereas
In Example 2, it was 89, and the actual furnace durability index was 9 in Comparative Example 2.
In contrast to 5, the actual furnace life index of Example 2 was 108, and the denseness of the structure was improved, high hot strength and high corrosion resistance were exhibited, and the service life in the actual furnace was improved.

[0011] Comparative Example 2 was higher formed shape pressure to the 2.7 t / cm ^2, the tissue is degraded and hot strength and corrosion resistance is lowered, actual furnace life was found to be reduced.

[0012]

[Table 1]

FIG. 1 shows Example 1 and Comparative Example 1 described above.
Shows the relationship between the formation shape pressure and corrosion index for 2. As also seen from FIG. 1, when forming the shape <br/> pressure at CIP forming form method other than the required pressure range, the comparative example than in Example, has resulted in an actual furnace life is poor.

[0014]

According to the present invention, magnesia is 70 to 95% by weight,
According to the sleeve-type refractory molding method according to the CIP molding method of the present invention containing 5 to 25% by weight of a resin, the molding pressure is 1.
By setting the content to 8 to 2.5 t / cm ² , the composition becomes dense, the hot strength and the corrosion resistance are improved, and the durability can be improved.

[Brief description of the drawings]

FIG. 1 shows the relationship between the formation shape pressure and useful index.

Continued on the front page (72) Inventor Toshihiro Suruga 2-2 Funamachi, Yahatanishi-ku, Kitakyushu (72) Inventor Shojigawa 5-4-1-11, Akiyama Chuo, Kure-shi (72) Inventor Yutaka Onishi Kitakyushu-shi Kokurakita-ku Shinozaki 5-chome 33-33 (56) References JP-A-50-7 (JP, A) JP-A 2-172859 (JP, A) JP-A 4-187347 (JP, A) JP-A 57-185107 (JP, A) JP-A-6-142900 (JP, A) "Isotropic pressurization technology-Application of HIP / CIP technology to material development" Published by Nikkan Kogyo Shimbun, April 13, 1988, 8-9 Page, Figure 1.1, pages 81-86 (58) Fields investigated (Int. Cl. ⁷ , DB name) F27D 1/00 B22D 11/10 310 B22D 41/52 B28B 3/00 102

Claims (1)

(57) [Claims] 1. A container for handling molten metal, comprising :
70 to 95% by weight of Nessia, 5 to 25% by weight of carbon
A method for forming a sleeve-like refractory, comprising forming the sleeve-like refractory using a CIP molding method at a pressure of 1.8 to 2.5 t / cm ² .