The 15th Annual Colloquium of the Technical Association of Refractories, Japan (TARJ) was held in Okayama, April 16-17. Most of the 200 attendees were from Japan, but there were attendees from at least five other countries as well. Only six attendees were from the steel industry, despite its status as the main market segment for refractories. Forty-three papers were presented, including four that were recognized by TARJ as best of the year with the Wakabayashi Prize, and an invited lecture titled, “The Characteristics and Application of Deep Seawater.”
The three main topics of the program were steelmaking (40%), fundamental research (23%) and monolithic refractories (21%). Other topics focused on refractories for the environment and other industries. The Wakabayashi Prize papers included “In-Situ X-Ray and Microstructure Analysis of Slag Penetration into MgO Refractories,” “Synthesis of Whisker-Like Spinel from Gibbsite and Mg Acetate,” “Compaction Characteristics for Powder by Uniaxial Pressing” and “Effect of Alumina-Zirconia Grain Microstructure on Thermal Spalling Resistance of Refractories.”
Numerous papers dealt with iron/steel flow control devices, including slide gates, nozzles, tubes, tundishes, troughs and taphole mixes. One paper dealt with the effect of alumina grain size and fused silica content in alumina-silica-30% carbon mixes. Mixes containing coarse and fine alumina, along with a lower silica content, had higher strength. Mixes with only coarse alumina had better thermal shock resistance with increased silica content (up to 30 wt%), due to the development of microcracks around the aggregate grains. The corrosion resistance was also better with coarse and fine alumina, although in all cases it decreased with increasing silica content.
Another paper described the development of a submerged nozzle with higher corrosion resistance. An improved material, which was localized on the nozzle surface and included secondary spinel and lower carbon content, had higher thermal expansion and better insulating character.
All of the Wakabayashi Prize-winning papers were fundamental studies. Other examples of fundamental papers included “Microwave Furnace for Sintering Ceramics;” “New, More Definitive Rotary Corrosion Testing Apparatus;” “Evaluation of the Labyrinth Factor for Porous Plugs;” and “Study of ZrO2-BN-TiC-TiB2 Composite.”
The topic of one monolithic refractory session was blast furnace taphole mixes, including densification, drillability and hardening behavior. Another monolithic refractory paper dealt with the relationship between properties and performance of the metal/slag line of a blast furnace trough castable. The best corrosion/wear results were realized by mutual optimization of the constituents (fused spinel, SiC and superfine alumina). Other monolithic refractory papers included “Abrasion Testing” and “Effect of Aggregate Porosity on Castable Properties.”
Refractories Industry Status
The ongoing decline in refractories consumption by the consuming industries in Japan, especially the steel industry, is the result of a variety of factors, including improved refractories, engineering and operations. As a result, the annual production of refractories has continued to decrease. Between 1991 and 2001, annual refractory production (million metric tons) in Japan decreased 27%, from 1,747,000 to 1,269,000. Likewise, for the same time period, the total annual market value decreased 34% to 178.1 billion yen in 2001. Employment in the Japanese refractories industry has decreased 33%, from 10,400 in 1991 to 7000 in 2000 (the latest year for which employment data are available). Lifetime employment in Japan is becoming a relic of the past. Refractory imports from China, India, Thailand and Korea, among others, have had a significant negative impact on the Japanese market. Imports increased from about 30,000 metric tons in 1991 to 128,000 metric tons in 2000, with a major increase in tonnage from 40,000 in 1993 to 96,000 in 1995. The unit price of imported refractories is approximately 45% less than Japanese-made refractories.
The advance of refractories technology is continuing in Japan, with fundamental and practical research studies resulting in property and field performance improvements that allow refractories to give longer service and provide economic benefits for the users of refractories. These improvements, which continue to benefit the customers, have had a significant negative impact on the refractories companies. The Japanese refractories industry has many concerns that must be addressed, such as the continuing decline in refractory demand and market value, increasing imported refractories, attracting new employees, and profitability.