DEVELOPMENT OF NEW REFRACTORY MATERIALS
EXHIBITING INCREASED BARRIER PROPERTIES
A. V. Leont’ev
Translated from Novye Ogneupory, No. 10, pp. 33 – 35, October 2007.
Original article submitted January 29, 2007.
OOO Kontakt together with Bogdanovich OAO Ogneupory has created for the first time in Russia compact
barrier chamotte articles with high barrier properties. These refractories operate successfully in electrolyzers
with a current strength of 300 kA. The quality indices of articles are not surpassed by overseas barrier
refractories and they are half the price of imported refractories.
Until recently production of refractories in Russia has
been orientated towards ferrous metallurgy. It is assumed
that the severe service conditions for refractories in ferrous
metallurgy are known to provide the necessary service in-
dices in nonferrous metallurgy where the temperature level
and corrosiveness is lower. However, in the majority of cases
the potential of these refractories in furnaces of nonferrous
metallurgy enterprises has not been realized.
An important consumer of refractories in nonferrous
metallurgy is the aluminum industry. The greatest volume of
materials is in the production of primary aluminum, in parti-
cular in lining the cathode section of an electrolyzer, and in
lining rotary furnaces for alumina production.
The main bases for using refractories and insulation in
the aluminum electrolyzers are as follows: lower heat loss to
the surroundings, which provides a lower working stress in
the bath; maintenance of the optimum temperature regime
for electrolysis; compensation of temperature deformation
that arises during heating of electrolyzers without disturbing
the integrity of the lining; protection of the steel casing of
electrolyzers from local overheating, creation of a physical
and chemical barrier to sodium and fluorine vapor; existence
of a marked increase in the service life of electrolyzers.
The choice and assembly of the arch using materials with
the required properties plays an important role in the endu
rance and maintenance of stability of thermal equilibrium.
The main indices by which domestic refractories are surpas
sed by overseas refractories, known under the trade marks
AT-21, BB-20, Cilgard, Alubar-1100 are: deviations from
geometric dimensions, high porosity and less mechanical
strength, lower resistance to molten cryolite.
Proceeding from this specialists of OOO Kontakt were
set the following task:
development of comprehensive lining for the arch of the
cathode part of an electrolyzer;
laboratory testing of the barrier materials obtained;
assimilation of test methods for barrier materials by a
output of test-industrial batches of barrier chamotte artic-
les (BCA), development and confirmation of technical con-
Currently this work is being carried out, they have been
introduced into industrial production, and BCA of six sizes
are being supplied to aluminum plants.
Depending on the functions and position in a cathode of
the non-angular part of normal hearth it may be subdivided
into three types of materials: soft materials, that are
underlays for the cathode blocks and provide their alignment
(layer of dry barrier mixture); dense refractory materials acting
as a base on which blocks are placed; materials with low
thermal conductivity reducing heat loss from the electro
lyzer. Dense refractory materials, i.e. the main protection
from fluorides, help to reduce the temperature in the insulat
ing materials arranged below.
Spesialists of OOO Kontakt have studied attentively and
analyzed the service of the lining of operating electrolyzers,
production of test workshops and overseas manufacturers.
Taking account of the data obtained a specific task was set,
i.e. creation of a set of arch linings for the cathode section of
an electrolyzer. During its fulfilment BCA have been ob
tained with low linear thermal expansion coefficient (LTEC)
whose use has reduced the danger to cathode blocks during
firing and start-up of an electrolyzer to 15%.
Refractories and Industrial Ceramics Vol. 48, No. 5, 2007
1083-4877/07/4805-0323 © 2007 Springer Science+Business Media, Inc.
OOO Kontakt, Russia.