Every day, refractories serve the very important
functions of controlling and confining high temperatures and chemical reactions
in industrial processes worldwide. The theme of the 43rd Symposium on
Refractories, held March 28-29, was Thermal Management. The meeting, which was
co-sponsored by the St. Louis Section and Refractory Ceramics Division of the
American Ceramic Society, was attended by 110 people. In addition to the
technical program summarized below, an exposition showcased 19 exhibitors.
V. Pandolfelli of the Federal University of Sao Carlos,
Brazil, discussed the function of organic fibers in the dryout of castables. He
shared several of his conclusions, including:
- The length of organic fibers can be
significantly reduced in the mixing process. The best fiber length after mixing
is 3 mm, while the best fiber diameter is 15 µ.
- The permeability of castables increases faster
with more fiber content.
- There is no effect of fibers on the drying rate
of a castable before melting, but as soon as they melt (polypropylene's melting
point is 165°C), the drying rate increases because the permeability
- A polyethylene fiber was developed with a lower
melting point (100°C), which lowered the temperature at which the permeability
Energy Control and Cost Savings
F. McMann of North American Mfg. Co. discussed the
management of energy usage in rotary and tunnel kilns, starting with a review
of the variables that can be monitored and controlled. It is a common priority
to reduce operating costs while not decreasing product quality, which can be
achieved by retrofitting existing kilns.
K. Moody from Thermal Ceramics reviewed various new
insulation lining options to cut energy consumption in refinery and
petrochemical plant heaters, as related to possible energy shortages and the
desire to reduce operating costs. Lining designs, such as those made for floors
and upper/lower walls that can reduce heat loss by 25-40%, were discussed and
Unifrax Corp.'s A. Cadin presented information and
examples of insulation options for thermal management that are increasingly
important because energy prices are rising, and industry in general needs to
reduce the energy requirement per unit of production. A wide variety of
insulation designs are available, including full thickness linings, surface
veneers and thermally efficient backup.
R. Chambers from Fosbel discussed the cost and energy
savings associated with in-situ
(hot) furnace repairs in
glass furnaces, and presented data for several actual cases.
To optimize the energy conservation of industrial
furnaces, heaters, etc., it is important to use valid thermal conductivity data
to design linings and select repair/retrofit materials. J. Hemrick (Oak Ridge
National Lab) discussed progress in developing the equipment and procedure for
measuring the thermal conductivity of large refractory samples (e.g., 200 x 250
x 50 mm) using an infrared lamp. In addition, C. Kistler (Orton Ceramic
Foundation) reviewed an update of the ASTM C-201 water calorimeter units for
measuring thermal conductivity. The changes have resulted in thermal
conductivity results that are roughly 10% higher than the 1993-era ASTM
procedure, and have the potential to come within 10% of the hot-wire test
H. Shulman of Ceralink, Inc. reviewed the procedure and
benefits of microwave-assist technology (MAT) for manufacturing refractories,
wherein radiant heat (electric or gas) is combined with microwave energy. MAT
was found to provide a heating rate two times faster than gas alone for a
Castables, Anchors and Mullite
R. McConnell from Almatis discussed the aging behavior of
alphabond binder in four self-flow castables. Alphabond is more hygroscopic
than CA cement and requires special packaging. Initial results for aging at 35°C
and 85% RH showed that alphabond-bonded castables have reasonable shelf life
without special packaging. More testing will be done to clarify the aging
effects and shelf life.
N. Longshaw (CERAM Research, UK) reported initial findings for a
new test in development to measure the corrosion of metal anchors. Such a test
is needed because metal anchors are implicated in the failure of an estimated
500,000 tons of castable linings each year.
Kyanite Mining Corp.'s D. Jain presented results of a
controlled study with several sources of alumina, silica, mullite and kyanite
to see how much mullite forms and at what temperature (1000 to 1650°C). It was
found that, for pure alumina and silica, no mullite forms until 1500°C.
Additionally, kyanite converts to mullite in the range 1250 to 1450°C, and
silica fume and alumina can be replaced by micronized kyanite to enhance
mullite formation at lower temperatures.
The 40th T.J. Planje-St. Louis Refractories Award was
presented to Leonard Krietz, vice president of R&D for the Refractory
Materials Division of Plibrico Co., LLC. A graduate of Rutgers Univ.,
he has worked in the refractories industry for more than 30 years.
The Al Allen Award for the best published refractory
paper in 2005-2006 was presented by the Refractory Ceramics Division to V.
Pandolfelli for "Setting Additive Influence on the Thermomechanical
Properties of Wet Shotcrete Refractory Castable Matrices," which appeared
in the American Ceramic Society Bulletin
, August 2005.
St. Louis Symposium Proceedings
can be obtained by contacting Patty Smith of the University of Missouri-Rolla at
(573) 341-6265 or e-mail email@example.com