REFRACTORIES REVIEW: Destination, St. Louis
OverviewsI gave a talk titled "The Sleeping Giant (China) Has Awakened," sharing data for the increasing production of steel and cement in China, which has contributed to a 132% increase in refractory production since 2000. The refractory tonnage is 22.8 million metric tons, approaching a level four times greater than the highest U.S. production (in 1979). The annual refractory market value in China has increased 241% since 2000 to US$7.9 billion, which is about three times higher than the highest U.S. market value of $2.57 billion in 1997. Additionally, I reviewed the Chinese refractory activities for the iron/steel industry, raw materials, and monolithic refractories, and mentioned various issues, such as pricing impact, transporation, variable quality, etc. I also indicated that a variety of business and research opportunities for foreign companies exist in China.
B. Carty of Alfred University discussed an allied fundamental study of the bond between four-sided ceramic aggregate shapes (tetrajacks) and Portland cement, in which improved bonding was realized. He found that using an aggregate with increased roughness didn't always improve the strength. Carty plans to do a study of mixes with tetrajacks bonded with refractory cement to better understand the strength development mechanism.
Raw MaterialsG. Gapinski and J. Scanlon reviewed the history and application of silica fume. In the early '60s, silica fume was effectively used in high-alumina brick, which was the dominant refractory product for most applications. The use of silica fume in castables came later and contributed to the development of castables that had properties equivalent to or better than brick, which led to a major transformation where castables are increasingly being used in place of brick.
G. Wagner of Saint-Gobain reviewed the status of silicon carbide (SiC) for refractories. The worldwide production capacity of SiC is about 1 million metric tons, of which roughly 25% is used in refractories/ceramics. He highlighted the use of SiC in Al reduction cells, torpedo cars, blast furnaces (taphole mixes, troughs and runners) and municipal waste incinerators.
P. Ormond of Aluchem discussed the economics of alumina for the refractories industry. He noted that the cost of bauxite will continue to increase and said that the challenge for refractory manufacturers is to respond to raw materials price changes in ways that provide the best value to their customers. C. Dusfresne of Cambior described the rejuvenation of Guyanan (South American) bauxite, with a capacity of 390,000 tons per year of calcined material, and discussed the hope of capitalizing on this new resource in the face of uncertainties of the supply of bauxite from China.
CastablesC. Parr of Lafarge Aluminates compared castables bonded with calcium aluminate cement (CAC) and alternative bonding systems. He indicated that the standard classification of alumina and alumino-silicate castables (ASTM C-401) needs to be revised. The commercial 70% alumina cement is now better than the cement of 15-20 years ago, based on the reduced standard deviation of selected properties. Much better knowledge is available on the interdependence of the cement, fillers and additives in castables. However, precautions are still necessary in the placement of mixes with reduced cement content, although the ease of installation has greatly improved.
B. McConnell of Almatis discussed the use of sprayed/cast microporous CA6-based insulating materials as an alternative to refractory ceramic fiber and other insulations. Used as the lining on a steel ladle preheater cover, a life of three years was achieved without the need for repairs. Other steel uses have included submerged entry nozzle insulation and cast shapes for reheating furnaces. Additional industries using CA6-based materials include glass, ceramic and petrochemical.
F. Cantelaube of Alcan Specialty Aluminas discussed the interchangeability of tabular and white fused alumina in a low-cement castable matrix, concluding that the switch between these raw materials must be done with care because properties can decline drastically.
2006 Planje AwardThe 39th T. J. Planje-St. Louis Refractories Award was presented to Subrata Banerjee, Ph.D. His 30-year career in refractories has included work with General Refractories Co., Magneco/Metrel, BMI Refractories, and as a consultant. He holds several patents based on his work with low-cement castables, sol-gel technology in castables, and shotcasting techniques.
The 2006 St. Louis Symposium Proceedings can be obtained by contacting Patty Smith at the University of Missouri-Rolla, (573) 341-6256 or e-mail firstname.lastname@example.org .