SCIENTIFIC RESEARCH AND DEVELOPMENT
DENSE REFRACTORIES MADE FROM CARBIDIZED GRANULES
O. A. Belogurova,
M. A. Savarina,
and T. V. Sharai
Translated from Novye Ogneupory, No. 5, pp. 43 – 47, May, 2015.
Original article submitted December 19, 2014.
The process of obtaining dense refractory materials based on carbidized granules of kyanite ore is examined.
The materials are tested in a multilayered lining on an experimental unit. Relations are found for the depend
ence of the temperature of the cold surface of the lining on its thickness and the dependence of the heat-flux in
dices and equivalent thermal conductivity on the thickness of the granular layer composed of mullite-cordier
ite thermal insulation.
Keywords: carbidized granules, mullite, silicon carbide, multilayered linings, heat flux, equivalent thermal
Low-grade and hard-to-concentrate ores of complex ma-
terial composition are now being industrially processed for
commercial use. However, their extraction and beneficiation
is costly, the quantities of useful components that are recov-
ered are small, and the resulting mineral concentrates do not
always satisfy the technical prerequisites and requirements
of modern industry. Studies we performed previously [1 – 5]
have shown that it is possible to use low-grade low-plasticity
alumosilicate-based natural raw materials from the
Murmansk region and industrial waste products to create a
number of new materials. The results obtained from studies
of the carbidization of the alumosilicate matrix show that
refractories made from these resources are likely to be strong
and resistant to heat and oxidation.
The notion of creating a refractory based on granules of
carbon and loamy clays was conceived by researchers D.
Cölle, C. G. Aneziris, W. Schärfl, and S. Dudczig in 2007
[6 – 15]. The loamy clays that were used were natural mix
tures of quartz and clay-based minerals composed of fine
fractions of microscopic kaolin particles and submicroscopic
alumosilicate-based amorphous phases. The binder of the re
fractory was carbonaceous resin that has a high melting point
and forms oriented graphite-like structures after coking. The
carbon-bearing alumosilicate composites which are produced
today are characterized by densities of up to 2200 kg/m
ues up to 20% for open porosity, and ultimate compressive
strengths higher than 30 MPa, depending on the chosen heat
treatment. These materials have undergone testing not only
in the sintering zones of shaft furnaces but also as monolithic
and shaped refractory products for use in the metallurgical
industry [6 – 15].
The goals of the investigation being discussed here were
to develop refractories of different compositions based on
carbidized granules of kyanite raw materials from the
Murmansk region and study the use of these materials and
previously developed materials in a multilayered lining.
For the pseudo-closed system Al
–C, the occur
rence of carbothermic reactions in a reducing medium leads
to the formation of SiC. The carbidization process necessar
ily entails the reduction of silicon dioxide, which is present
in the ore as a impurity and is precipitated during the
mullitization process. Thermodynamic calculations show
that reactions of SiO
with carbon can lead to the formation
of silicon carbide. This process is affected by the sizes of the
particles, their proximity to one another, and the type of car
bon-bearing reducing agent that is used [1 – 3]. The diffusion
of SiO within the volume of the specimen facilitates the
transport of silicon through the pore space and subsequent
carbidization (SiO + 2C = SiC + CO). The capture of gas
eous silicon monoxide and its bonding to form a carbide take
place on the surface of carbon particles. An increase in the
content of carbon particles is accompanied by an increase in
Refractories and Industrial Ceramics Vol. 56, No. 3, September, 2015
1083-4877/15/05603-0263 © 2015 Springer Science+Business Media New York
Institute of the Chemistry and Engineering of Rare Earth Ele
ments and Minerals at the Kola Science Center of the Russian
Academy of Sciences, Apatity, Murmansk Oblast, Russia.