Director Managing Executive Officer, Production, Research Center, Technical Dept.　 Masanori OGATA

Junya ITO

Last year, Shinagawa Refractories Co., Ltd. celebrated its 50th anniversary as a supplier of technically advanced mold powder for the continous casting of steel. Since its beginning in 1971, Shinagawa has conducted extensive development of this technology to become a technological leader. By providing a broad range of unique, high-quality products, Shinagawa has contributed significantly to improvements in continuous casting operations, helping to increase productivity and offer improved steel quality. At present, our products are widely used in many steel works around the world. This report will give a summary of the technological improvements made in Shinagawa's mold powder along with the technology trends in continous casting over the last 50 years, and the products that have resulted.

Eiji ISHIHARA, Masafumi NISHIMURA

It is prospected that, in accordance with the progress of environmental and ecological activities connected with achieving carbon neutralization by 2050, the ratio of steel production by electric arc furnace (EAF), which is characterized by a smaller amount of CO₂ emission, will increase in the steel industry. Consequentially, production of high-grade steel products would increase in EAF steel mill, resulting in intensification of secondary refining treatments in the teeming ladle to guarantee steel qualities. Since teeming ladle refractories are severely damaged by intensive secondary refining. Al2O₁-MgO-C brick is usually applied. As an alternative teeming ladle refractory, Al₂O-MgO refractory with superior corrosion resistance are introduced in this article as carbon free refractory for steel bath in teeming ladle in which intensive secondary refining is conducted. In practice, according to teeming ladle operational conditions, ALTIMA unburnt Al2O3-MgO brick, Al2O₁-MgO castable refractories and precast block fabricated with Al2O3-MgO monolithic refractory can be used in combination. By applying carbon free refractories with low thermal conductivity for the steel bath in the teeming ladle, suppression of heat radiation from the teeming ladle steel shell results in the reduction of CO₂ gas emission in EAF operation is expected along with prevention of molten steel contamination by the C component contained in refractories. In the case where a teeming ladle is relined with castable refractories, reduction of teeming ladle refractory unit consumption is expected by adopting partial additional repair work along with reduction of waste disposal. Because of such advantageous characteristics, carbon free refractories are practically applied for teeming ladle in several steel mills.

Koji ASAKAWA, Yuto SUZUKI, Masakazu IIDA, Shinsuke SUETAKE

It is anticipated that minimizing heat radiation from high temperature furnace bodies by utilizing refractory materials with low thermal conductivity, namely, heat insulation refractories will become more and more important because it effectively reduces consumed energy and CO₂ gas emissions. Since, due to its poor physical strength, application of low thermal conductivity refractory materials is limited, the mechanical strength of such refractory materials needs to be improved for broader application. In this article, heat insulation castable refractory applicable for furnace or vessel relining, newly developed fiber blended castable refractories and heat insulation board with ultra-low thermal conductivity and smaller plastic deformation even in application use as back relining are introduced one by one. They are categorized as thermal insulation refractories with improved mechanical strength. Application of these materials in various fields is expectable.

Hiroyasu NIITSUMA, Takayuki MATSUNAGA

One of the major issues with submerged entry nozzles (SEN) used in the continuous casting process is alumina clogging. Alumina clogging occurs through a complex process in which several and chemical reactions and physical interactions take place simultaneously. In order to prevent alumina clogging, suitable SEN application in terms of material chemistry as well as geometric design is essential. In this article, features of our four material types and two shape designs, which suppress clogging suppression, and their application results are described.

Hisashi TOMIYA

Spinel-C brick is characterized by superior MgO-C reaction resistance associated with high slag infiltration and corrosion resistance. Spinel-C brick exhibits better performance than conventionally applied MgO-C brick when applied to the lower vessel in the RH vacuum degassing unit as well as for bottom relining of the DC (direct current) electric arc furnace. It was inferred by microstructure observation on used bricks that better performance is realized by suppression of MgO-C reaction in spinel-C brick.

Yoshihiro TODA, Koichi IGABO, Tsuyoshi SUWA

In association with increase of recycled use of waste products and by-products in cement industry, furnace environment in cement rotary kiln has been changed harsher and harsher with diversified atmospheric conditions. In order to correspond to requirements for rotary kiln refractories whose damage patterns have been varied in connection with above mentioned changes in operational condition, magnesia-spinel brick products which are provided to cement industry by our company have been developed or modified in various aspects. In this article, line-up of magnesia-spinel bricks for cement rotary kiln is introduced along with characteristics and practical operation performance of newly introduced products.

Hidekuni NISHIGUCHI, Kiyoyuki KOMATSUBARA, Koji ASAKAWA

KOALA-mini has been developed on the basis of KOALA, which is a compactly designed portable gunning machine for small scale refractory repairing work which can be operated with just compressed air and water. KOALA-mini characterized with further reduces machine weight for better portability and improved performance in gunning work. Since, similarly to KOALA, KOALA-mini is compactly designed and weighs only 22 kg, it can be hand-carried into locations where space is narrow or facilities that can only be accessed via stairways. Examples of such locations or facilities include incinerator, heating furnaces, PCI facilities, top of coke oven batteries, KR type desulfurization impellers, top portion of blast furnaces or CDQ dust collectors. In practice, a steelmaking facility has been hot-repaired with KOALA-mini placed on the inspection deck, extending the service life of the refractories. By applying KOALA-mini in this way, it has become possible to repair by spraying even in facilities that could not be repaired with conventional gunning machines, which contributes to efficient and economical facility operation.

Kosuke OTA, Yumi KIMURA

Tundish refractory repairing material, CA-160-13T, which can be applied both for troweling on localized damage in the tundish wall and for casting at the periphery of renewed well block has been developed. Previously, in accordance with the damaged position of tundish refractories, different types of repairing methods were adopted with specially designed repairing materials. Newly developed repairing refractory material, CA-160-13T, enables tundish refractory repair work simply with one type of repairing material in association with rationalization of inventory management.

Gaku KOIZUMI, Kentaro UEMICHI, Hidenao SUZUKI

Kiln furniture is a generic name for refractory setting plates (called setters), refractory shelves, and refractory containers (called saggars) and they are utilized for broad applications, such as firing of electronics components, heat treatment of mixtures of powdery electronic raw materials, heat treatment of semiconductor-manufacturing tools, and so on. Our company has been providing lightweight kiln furniture composed of ceramic fiber as one of our commercial activities. In accordance with newly arising requirements derived from recent progress in a variety of industries, our line-up of lightweight kiln furniture products has been upgraded and expanded. Among them, lightweight saggars for sintering cathode material for lithium-ion battery (LIB) and lightweight setters for heat treatment of electronics devices are introduced in this article.

Masahiro YOSHIKAWA, Terumitsu ICHIMORI, Teruhiko TAKEDA

SSNB is made by adding hexagonal boron nitride (h-BN) to silicon nitride (Si₃N₄) and has the excellent mechanical properties of Si₃N₄ and excellent thermal shock resistance and machinability of h-BN. By improving the microstructure of this ceramic, the strength and thermal shock resistance of the conventional SNB material are improved by 35 % and 15 %, respectively, on average. We are promoting the application of this material as a molten metal and heat resistant material in a harsh thermal environment. This report outlines the SSNB characteristics and applications.