Corporate Chief Executive Officer, Shinagawa Refractories Co., Ltd.

Hiroyuki Fujiwara

Masakazu IIDA, Shingo FUJITANI, Shigefumi NISHIDA, Eiji ISHIHARA and Takashi IIDA

This article describes green refractory products.“Green refractory”is an eco-friendly category bothconceived by and unique to SHINAGAWA Refractories. These refractory products include more than20 mass% of externally/internally recycled refractory materials and/or byproducts derived from otherindustrial sectors. They are created by using suitably treated and properly managed recycled materials and byproducts as well as modifying virgin raw material formulas to maintain the distinctive characteristics of each product. Green refractory products show a low“carbon footprint of products (CFP)”, thus,greenhouse gas emissions across the whole supply chain can be reduced by expanding green refractory applications. To this end, the lineup of products in the category of green refractory is being expanded.Recently, versatile chamotte brick, high-alumina brick, magnesia-chrome brick, magnesia-spinel brick,MgO-C brick, ALTIMA brick, versatile castable, castable for tundish, basic spraying mix for electric arc furnace repair and taphole clay for blast furnaces have been added to its lineup.

Haysler LIMA, Douglas GALESI, Vladnilson RAMOS, Hamilton GUIMARÄES and Isaque GRANUZZIO

Shinagawa Refratários do Brasil Ltda.

The performance of a steel mill relies heavily on the stability of its production equipment, with combined blowing being crucial to ensure the chemical homogeneity of the steel, thereby decreasing the total iron content in slag (metallic yield) and enhancing the dephosphorization rate. The combined blowing system comprises a set of tuyeres for injecting inert gases from the bottom. During tuyere operation, various fluid dynamic phenomena occur, leading to increased refractory wear, decreased lifespan, and disruptions in combined blowing operations. This study aimed to develop a new tuyere design to enhance the steel mixing rate and reduce wear, ultimately improving the efficiency of combined blowing.　

Tetsuya FURUKAWA and Eiji ISHIHARA

The pore structure in porous brick is an important factor in determining its permeability and molten steel infiltration resistance. Pore structure, more exactly, the pore size in the pore structure, is usually evaluated by BET method, mercury penetration method or X-ray CT method. The X-ray CT method is appropriate for measuring an object which is characterized by complex pore structure with relatively large pore size. The differences in the pore structure in porous bricks were quantitatively evaluated by analyzing photographed X-ray CT images of porous bricks with different permeabilities.

Eric Yoshimitsu SAKO, Heloisa Daltoso ORSOLINI, Bianca Maria Gomes da SILVA, Douglas Fernando GALESI, Deivison Carlos Fontes HESPANHOL and Wiliam ALVES

Shinagawa Refratários do Brasil Ltda.

Refractories are often exposed to thermal variations during their operational cycle, such as in torpedo cars and iron ladles, where molten metal is loaded and unloaded. Dealing with that aggressive thermal shock is not straightforward and the most common approach for these materials is to optimize the carbon sources, increasing the thermal conductivity of the bricks and reducing the thermal gradient between the hot and cold faces. If, on one hand, the material becomes more resistant to thermal shock damages, on the other hand, its higher conductivity imposes a negative consequence: higher thermal loss during operation. In this work, inspired by intelligent microstructures with the ability to adapt to the most severe environmental conditions, an innovative approach was evaluated, aiming at obtaining an Al2O3-SiC-C brick formulation designed to present a self-healing behavior, without variation in the carbon sources or content. The new developed structure successfully regenerated the cracks initiated during thermal cycles, resulting in an even tougher material after thermal shock tests. Other properties such as mechanical resistance, oxidation, hot mechanical properties and corrosion resistance also showed promising results, pointing out the birth of a smart self-healing technology, able to completely change the role of refractories in thermal cyclic operations proven by field tests.

Chiho KURIYAMA, Kazuya NAKABO and Junya ITO

 Mold powder is added onto the molten steel surface in the water cooled mold. The mold powder melts from the heat of the molten steel, forming a slag film of several hundred micrometers to 1 mm thick that flows between the solidified shell and the mold. The slag film partially crystallizes when cooled by the mold, regulating the amount of heat transfer from the cast strand shell to the mold by altering the degree of crystal formation. Controlling heat transfer helps to prevent cracking on the steel surface. It is essential to measure the crystallization and heat removal properties of slag films. A slag film is formed when the molten and crystalline layers are intermingled, with the thickness of the crystalline layer progressively increasing towards the bottom of the mold. Therefore, it was difficult to reproduce such a condition in the laboratory, and that means it was difficult to evaluate the real heat transfer characteristics in the mold. A method for evaluating the heat transfer characteristics of slag film, where both molten and crystalline layers coexist in a mold, has been developed. This method utilizes an ultra-high speed heating test system that employs two carbon heaters, which was developed by the Okayama Ceramics Center. Two slag films of mold powder with distinct crystallization characteristics were prepared and assessed using an ultra-high speed heating test system with one-side heating, replicating actual casting conditions. The results of the experiments confirmed the method’s effectiveness as an evaluative tool, as the measurements demonstrated a strong correlation with the outcomes from actual casting.

Riccardo A. M. MONTUORI, José R. FERNANDES, Daelson U. da SILVA and Vladnilson P. de S. RAMOS

Shinagawa Refratários do Brasil Ltda.

Refractory castables are crucial in various regions of cement rotary kilns, facing severe operational conditions such as high-speed raw material flow, the use of alternative fuels resulting in alkali, sulfur and chlorine infiltration into the refractory lining, and temperature fluctuations. Moreover, the drying step of such monolithic refractories is energy-intensive; however, BestDrying technology enables significant energy savings and increased productivity due to faster drying curves, allowing kilns to resume operation quickly. In this context, this study presents experimental results of BestDrying castables under development for cement rotary kilns, focusing on the assessment of the physico-chemical properties responsible for their superior drying performance. Additionally, tests simulating operational conditions in cement kilns are discussed, highlighting the potential effectiveness and durability of BestDrying castables in challenging industrial scenarios.

Koichi IGABO and Yuto MIYATA

The formation of a stable coating layer on bricks relined at the burning zone in cement rotary kilnsis one of the important factors for enhancing the durability of refractories. By investigating samples of magnesia-spinel brick obtained from a cement rotary kiln as well as carrying out simulative experiments on liquid slag penetration into brick, it was clarified that stability of the coating layer is influenced by the anchor effect realized by penetration of cement clinker liquid phase into brick with a tendency for the cement clinker liquid phase to penetrate mainly into the micropores of magnesia-spinel brick. Based on the simulative experiment result in which liquid phase penetration into magnesia coarse grain was influenced by the type of magnesia raw material, a new magnesia-spinel brick, ELK-8X-1, was developed by implementing an improved coating property.

Johannes BOERSMA, Annelies NIEWIJK and Zhenlan GAO

Gouda Refractories BV and Suez Groupe

Selecting the most suitable refractory lining from various types/grades of products provided by different suppliers for the hazardous waste incineration rotary kiln is not an easy job to reach a 23-month lifetime. Real-life industrial scale test is time-consuming, i.e., only one or two new products can be tested each year or every other year. Crucible test is a fast way to give a first assessment to test the adaptability of a given product to a slag. However, the classic visual observation to determine the slag penetration zone is usually inconclusive when the materials of the same group are tested and can be sometimes misleading. In this study, crucible tests were performed for 10 commercial chromia-corundum bricks from various sources. After examined with detailed analysis with SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-Ray Spectroscopy), highly precise quantitative values of corrosion zones width for samples are derived. A non-dimensional number, the Wear ratio, is introduced as a quantitative criterion to characterize the refractory corrosion resistance. By using this Wear ratio, a correlation is found with the chromia concentration. Quantitative results obtained by this criterion are in line with the real-life observations of industrial scale tests.

Kanae NISHIO, Kazuya NAKABO and Tamiatsu KOYAKE

CAE analysis is used for research and development in various fields, including the refractories industry. In this report, we present examples of analyses conducted using the software applications we have adopted. Two types of analysis software were utilized: thermal analyses of the steel ladle and thermal stress analyses of heating tests under constraints, which were carried out using Marc, and the flow analyses of molten steel inside the continuous casting mold and the analyses of the behavior of inclusions in the tundish, which were carried out using scFLOW. Thermal analyses contribute to carbon neutrality efforts and the achievement of the Sustainable Development Goals (SDGs), while thermal stress analyses help estimate the causes of damage and indicate directions for improvement. Analyses of molten steel flow and inclusion particle behavior can enable one to visualize the flow and motion, leading to improved quality of clients’products. We aim to contribute to the further development of refractories by actively utilizing CAE analyses.

Tomohiro AOYAMA, Kentaro UEMICHI and Hidenao SUZUKI

Isolite Insulating Products Co., Ltd.

The demand for microporous insulation material predicted to increase more and more, because of its great contribution to energy conservation and/or reduction of CO2 emission realized by superior thermal insulation efficiency. In addition to the microporous insulation material products which have been provided as LTC series by the authors’company, microporous insulation material with flexibility, LTC-FL, is developed. Flexible microporous insulation material, LTC-FL, has been introduced in this article.

Hiroki BABA, Keisuke INUKAI, Naohide HAMAMOTO and Hiroyasu NIITSUMA

For steelmaking of Ca-treated API steel grades, two component SV plate in which a small piece of ZrO2 plate with superior corrosion resistance to Ca component is inserted at the critically damaged area (central bore and major sliding area) of Al2O3-C SV plates. However, difficulties such as localized damages on the ZrO2 plates by sticking or FeO corrosion caused by oxygen gas cleaning as well as exfoliation of the ZrO2 plates out of the base Al2O3-C SV plate during inspection/repair work with full-opening of SV mechanism accompany such two component SV plates. In this regard, new basic refractory SV plate material, SVR-FB9, is developed. Sticking damage is suppressed through the addition of carbon in SVRFB9, and its basicity also gives it sufficient durability against oxygen gas cleaning. SVR-FB9 implements enhanced corrosion resistance to Ca-treated API steel grades as well as improved strength, so it is applicable for large-sized single material SV plates, so it is expected that, because of the compatibility of SVR-FB9 plate to the Al2O3-C SV plate commonly applied for general steel grades, coped with sudden schedule changes in the steelmaking process will be more easily.

Kiyoyuki KOMATSUBARA, Natsumi HIGASHIKAWA and Ryuta YAMADA

After relining with a coating mix, the tundish is usually preheated quickly. In order to prevent incidents caused by quick preheating, such as explosive spalling, adequate drying properties are provided to the tundish coating mix by blending fiber. We establish a fiber blending technique for blending large amount of fiber in order to accomplish the reduction in thermal conductivity of coating mix roughly 40 %. By utilizing a fiber blending technique for the tundish coating mix, gunning and troweling coating mixes with improved drying property and dismantling property were developed.

Ryo TSUKADA, Takahiro KAGO and Shigeru KOMORI

By applying clay with a good swelling property, a high durability troweling repair refractory material, in which colloidal silica is used as binder, was newly developed. Similar to conventional cement blended troweling repair refractory, the newly developed troweling repair refractory, CCT-A620T, is applicable for repair work on reheating furnace skid pipe. Since damage caused by cracking and/or peeling-off is reduced through the use of CCT-A620T, the reduction of repair refractory consumption is achievable.