Chairman H. NISHIO

Godo Steel, Ltd. S. KURASAKO, T. ANAN, K. YOSHIZAWA and O. TAMURA
Shinagawa Refractories Co.,Ltd. M. Ogata and T. Matsunaga

In order to improve surface quality of continuously cast bloom, both the reduction of "air gap" between the mold face and solidifying bloom and the reduction of biased flow in the mold were focused on. Based on solidifying bloom shrinkage calculations, the mold taper was improved to reduce the air gap.
The flow pattern in the mold was simulated by water model, and the SEN was improved to "mogul" design.
As a result of these measures, the occurrence of the surface cracks was reduced to one tenth of the original. This improvement seems to be the result of even solidification of molten steel in the mold.

S. Uchida

Heat-transfer analysis was conducted in order to study the heat balance in the torpedo ladle. More than 40% of liquid pig iron heat consumed when being transported by the torpedo ladle is absorbed and stored in the wear lining.
Reducing the quantity of heat absorbed and stored in the wear lining is important.
ECONOS bricks, which our company developed, were found to be effective for reducing the quantity of heat lost, which is strongly correlated with controlling temperature drop of liquid pig iron.
On the other hand, insulation bricks which were applied as the safety lining were effective for reducing the quantity of heat radiated and lost from the shell.
They were indirectly effective in reducing the temperature drop of the liquid pigiron. In order to most effectively reduce the drop in temperature of liquid pig iron, it is important that the ECONOS lining is combined with an insulation safety lining with optimumly designed properties and proportions.
Present analysis techniques are helpful for optimizing such designs.

M. NANBA, H. SASAKI and M. NISHIMURA

Unshaped refractories are widely used for various places and functions.
Appropriate curing and drying conditions are necessary for good construction.
Rapid drying causes explosive spalling in the worst case and it can produce high pressure water vapor which causes cracking.
A rapid drying condition was determined from the result of the explosive spalling test, and rapid dry samples were made.
The properties of those samples were compared in order to study the influence of rapid drying on castables.

M. IIDA and K. OGURA

To analyze the metal/slag drainage rate variation during blast furnace tapping, a mathematical model for calculating the pressure drop of the coke packed layer as well as the tap hole tube was proposed.
The calculated results reproduced the drainage rate variation and tapping time fluctuation of a commercially operated blast furnace. It was found that tapping time is influenced not only by tap hole diameter enlargement but also by coke consumption.

K. INOUE and S. UCHIDA

The reactivity of various refractory materials with Na and K contained in biomass wastes, which are expected to be recycled for energy, was studied using a Tanmann furnace with the temperature set to 1200oC. An accelerated experiment was also performed at 1300oC using actual incineration fly ash as an example, and a guideline for the selection of refractory materials was obtained.

M. YOSHIDA and H. TOMIYA

Al2O3-MgO-C brick has been widely used for the metal line of steel ladle linings. We developed "CALEAD" , a high performance lightweight Al2O3-MgO-C brick. CALEAD has about 10% lower thermal conductivity and bulk density than ordinary Al2O3-MgO-C bricks in spite of having almost the same characteristics.

M. YOSHIDA and H. TOMIYA

Carbon-free materials such as MgO-Cr2O3 brick and dolomite brick are applied to ladle lining for manufacturing ultra low carbon steel. However, they have the drawback of spalling easily from slag penetration. This report describes "low carbon MgO-C brick" , which reduces carbon pick-up into steel and has excellent slag penetration resistance and spalling resistance.

T. KAGEYAMA, M. KITAMURA and T. MAKIHARA

This new castable material for the blast furnace trough using silica sol as a binder has high resistance against steam explosion during drying because of very low water vapor pressure generated with rapid heating, and it needs only two thirds drying time compared to ordinary low cement castable material.
Silica sol castable also has the same or higher corrosion resistance than low cement castable, therefore, it has a high future growth potential for shortening trough repairing time.

M. KITAMURA, T. IIDA and Y. NIIYA

We focused our research on several different particle sizes of carbon black. As a result, we developed castables using two kinds of carbon black with high corrosion resistance and spalling resistance, while retaining workability.
In actual use, the wear rate was significantly reduced. Cracks, which sometimes occurred in the ordinary castables after use, were reduced by using the newly developed castables.

H.SASAKI, K. KOMATSUBARA and T. KOYAMA

Conventional carbon bonded gunning mixes have the draw backs of the adhesion significantly declining at over 1300oC.Therefore, it was necessary to lower the temperature of the repaired area with excess water.
The developed items are carbon bonded gunning mixes which have substantially improved adhesion at high-temperatures of over 1300oC by using new technology adhesion aids.

E. ISHIHARA and K. SASAKI

In the secondary metallurgy refining process, inert gas such as argon or nitrogen is injected into the molten steel via gas purge plugs arranged in the bottom of the ladle for stirring the liquid steel with other additives.
This improves reaction efficiency and homogenizes steel temperature and chemistry.
Shinagawa Refractories Co., Ltd. has developed the new slit plug, which is designed to allow a targeted gas flow rate to be easily obtainable with structurally advanced slits, successfully provides long service life and a large amount of gas flow at many refining ladles.

Y. IWAMOTO, T. SUZUKI and B. HE

It is necessary for mold powder to improve insulation properties in order to improve steel quality.
Granulated mold powder is required to maintain a good clean working environment; however, granulated mold powder does not insulate as well as fine mold powder.
Granulated exothermic mold powders with metal were developed in order to both improve insulation properties and maintain a good working environment. The new technology of adding metal material to granule mold powders provides sufficient heat to molten steel and is able to improve steel quality.

K. IGAMI

An Inorganic Agent for Preventing Carbon Electrode Oxidation We developed an oxidization prevention agent which suppresses surface oxidization of carbon electrodes. By applying it to an electrode with a spray gun, excellent performance is demonstrated in reducing its unit consumption. Aｎ Inorganic Agent for Preventing Hot Metal Adhesion We also developed a paint which suppresses the adhesion of hot metal to refractories by coating their surface. Prevention of hot metal adhesion and growth are anticipated.

T. Omoto