Wen Tie Guang

Managing Deputy General Manager, Liaoning Shinagawa Hefeng Metallurgical Material Co., Ltd.

Nathan LEICHT

Shinagawa Refractories Australasia Pty Ltd

Takuma KANAGAWA, Kenji SUZUKI and Takashi IIDA

To realize satisfactory durability of Al2O3-SiC-C castable refractories for blast furnace trough, its physical properties need to be secured at elevated emperatures. Pitch powder is frequently applied as a raw material for carbon component which influences the physical properties of castable refractories. The influences of the characteristics of blended pitch powder, such as softening point, QI value or amount of β-resin, on physical properties of castable refractory bodies were investigated. A high correlation was observed in a series of experiment between the amount of β-resin in blended pitch powder and major physical properties of castable refractories, indicating that the amount of β-resin is one of the important guideposts for selecting pitch powder to be blended in castable refractories for the blast furnace trough.

Deivison Carlos Fontes HESPANHOL, Eric Yoshimitsu SAKO, Heloisa Daltoso ORSOLINI, Bianca Maria Gomes da SILVA, Douglas Fernando GALESI and Jamilson Leal de Souza FERREIRA

Shinagawa Refratários do Brasil Ltda.

A stable blast-furnace operation is strongly associated with the performance of tap hole clay, which is usually damaged by the combined effect of slag corrosion and pig iron erosion. As such scenario has recently become more challenging for the steel producers due to the use of lower quality raw-materials and lower cost operational practices, Shinagawa Refractories Brazil developed a high-performance solution based on an innovative tap hole clay with a graphene-like structure. Owing to an outstanding chemical resistance and, consequently, a stable mushroom and metal flow, such technology allows operations with reduced fuel consumption, helping to reduce the CO2 emissions and the refractory usage in the ironmaking area.

Gaku SHIMADA and Eiji ISHIHARA

It was clarified that the damage rate of MgO-C brick is influenced by graphite content by an investigative experiment in which MgO-C bricks relined in test vessel were heated up along with iron or steel to the Ultrahigh temperature up to 1800 ℃ in a high frequency induction furnace. It is inferred that the damage progressed in two steps, vanishment of the brick matrix near the heated surface associated with formation of a void region in the first step and the capture of the remaining coarse magnesia particles in molten metal in the second step. It is indicated that MgO-C reaction plays a role in void region formation and deterioration degree of brick structure near the heated surface. This depends on graphite content as well as on heating temperature, and influences the transience of gas phase generated by MgO-C reaction.

Patrícia Alves Silva de Resende BRUM, Vladnilson Peter de Souza RAMOS, Douglas Fernando GALESI, Ariovaldo do NASCIMENTO, Haysler Apolinário Amoroso LIMA and Hamilton Cesar GUIMARAES

Shinagawa Refratários do Brasil Ltda.

The companies’ commitment to zero CO2 emissions by 2050 has promoted a huge effort in the search for alternatives to replace conventional products, aiming to drastically reduce the carbon footprint. In refractory industry, for example, materials produced at low temperatures have been researched to replace high temperatures fired bricks, with significant CO2 emissions in their processing. This is the case of MgO-Cr2O3 products, used as refractory lining at RH degassers. In addition to the environmental appeal for CO2 reduction, the elimination of chromium is also a pursued objective, mainly due to the possibility of contamination of the environment by Cr＋6. Additionally, new possibilities for safe recycling can be explored with the absence of chromium. This work presents the efforts in the development of unfired Cr-free alternative refractories for application in RH degassers, to contribute with environmentally friendly products.

Hiroyasu NIITSUMA, Keigo FUJITA and Takayuki MATSUNAGA

Submerged entry nozzles for thin- and medium-thick slab continuous casting machines, which have been widely applied in recent years, consist of a cylindrical inlet section and a thinly spread, flat submerged section, which easily causes unbalanced outlet flow and poses an issue in terms of quality improvement of cast slabs. In addition, if the flat section is extremely wide, the weight increases, and handling becomes an issue. In this study, we developed a design that can eliminate mold level fluctuations and biased flow conditions while making the flat section compact. By keeping the inner bore cross-sectional area of the flattened section approximately 1.5 times that of the upper cylindrical section, the flat part can be made compact. The DiA design was applied to the outlet port, with the upper face angled downward and the lower face angled slightly upward or horizontally. This port design further reduced the meniscus velocity and the mold level fluctuations. It was also found that the introduction of a concave-step geometry in the upper cylindrical section eliminates the biased flow condition during inflow. We applied these developed geometries to actual equipment and confirmed their effectiveness in reducing the mold level fluctuation and biased flow conditions in the mold.

Junya ITO and Satoshi YAMASAKI

The mold powder used in continuous casting of the steel is melted by heat provided from the molten steel. At the same time there is a counteracting cooling effect from the water-cooled mold. If the mold powder melting behavior is inappropriate, excessive formation of “slag roping” can occur. This can adversely affect the operation stability as well as the steel quality. In order to facilitate development of improved mold powders, a new evaluation test method for predicting slag roping, which simulates the actual condition, has been developed. This new test has then been successfully used to determine the influence of mold powder physical form on the tendency to form rope. The results showed that the fine powder type and hollow spray dried granules type showed lower formation tendency, while agglomerated granules (without a porous core) showed a much greater tendency to exhibit excessive roping.

Kazuya NAKABO, Tamiatsu KOYAKE and Eiji ISHIHAR

In order to prevent cracking and peeling damage in relined refractory bricks which are restrained by neighboring bricks and furnace steel shell, brick joint design is quite important so as to regulate generated thermal stress in the proper range in overall brick relining design work. To experimentally reproduce joint damage under similar restraint conditions to a practical furnace, heating tests were conducted on two types of alumina bricks tightly relined in the test furnace, and the heating test results were verified with FEM analysis. It was concluded that the degree of compressed stress generated in restrained bricks is dominantly influenced by the modulus of elasticity with less influence by the creeping deformation which contributes to stress relaxation.

Koichi IGABO

Utilizing recycled raw materials, environmentally friendly bricks, which are labeled “Green Refractories”, for cement rotary kilns were developed. Similar performance to that attained by the original bricks, completely composed of virgin raw materials, is achievable with Green Refractories brick products, which contribute to the reduction of the life cycle CO2 emission volume, namely, reduction of CO2 emission volume derived from natural resources and energy consumed for production of raw materials. Deployment and development of Green Refractories for various fields is presently being actively pursued.

Eiji ISHIHARA

By establishing a recycling process to convert used high-grade MgO-C bricks from BOF converter linings into recycled MgO-C raw materials, an environmentally friendly product “MgO-C Green Refractories”, which contains the recycled MgO-C raw materials in a specific blend ratio, has been developed. In the production process of electro-fused magnesia, which is one of the main raw materials of MgO-C bricks, a large amount of electric power is required for the electric arc melting process. Therefore, the use of the “MgO-C Green Refractories” in various steelmaking furnaces and vessels is connected to the reduction of CO2 gas emissions. Through the promotions and expansions of “MgO-C Green Refractories”, we will contribute to the realization of a sustainable decarbonized society.

Kiyoyuki KOMATSUBARA, Hidekuni NISHIGUCHI and Ryuta YAMADA

Because of short construction time and simplicity in relining work, application of gunning refractory material has been increasing in recent years. Gunning material is generally used as repairing material for base refractories. Due to the above reasons, however, requirements for gunning material applicable for initial relining has increased in association with its better performance. In this regard, a new dry gunning material, SIG, in which binder solution is mixed with pneumatically transported SIG gunning material in the vicinity of the gunning nozzle was developed. In comparison with conventional gunning material, SIG gunning material exhibits almost doubled mechanical strength and superior quick drying properties.

Kyohei TOMITA, Kentaro UEMICHI and Hidenao SUZUKI

Isolite Insulating Products Co., Ltd.

Refractory ceramic fiber (RCF) has been classified as specified chemical substances (second category) in an amended ordinance in “Prevention of Hazards Due to Specified Chemical Substances”, in the RCF regulations. For this reason, the substitution of alkaline earth silicate wool (AES), which is exempt from the regulations, for RCF has been proceeding.

From among the authors’ company’s BSSR products the brand names of AES, BSSR board and BSSR vacuum formed shapes are introduced in this article, touching on their characteristics and applications. By modifying raw material compositions, some BSSR products have been improved so as to secure better health safety.

Atsuji KOBIKI, Kenji IKEDA, Madoka HAGA and Masahiro YOSHIKAWA

Shinagawa Fine Ceramics Co., Ltd.

N-TAC-XD1, a heat-resistant inorganic coating with corrosion-resistance, maintains its chemical stability in high temperature conditions and the coating layer does not deteriorate. This feature is expected to improve the working lives of mechanical parts coated with inorganic coatings on the surface of metals and other materials when used in high-temperature and corrosive environments. This report outlines the basic properties, effects, and applications of the heat and corrosion resistant inorganic coating developed by our company.