MATERIALS FOR THE LINING OF ALUMINUM ELECTROLYZERS
G. V. Arkhipov,
V. I. Borisov,
and A. M. Ivanova
Translated from Novye Ogneupory, No. 6, June, 2004, pp. 39 – 45.
Original article submitted November 6, 2003.
Results of an experimental study of the physicomechanical properties of refractory materials for the lining of
aluminum electrolyzers are reported.
AND TEST METHODOLOGIES
IK-4 and TÉP test complexes and a tensile testing ma-
chine equipped with an electric furnace for heating speci-
mens were used in the study of physicomechanical properties
of hearth blocks and mixes, refractory and heat-insulating
materials for the lining of electrolyzers.
IK-4 test complex (Fig. 1), equipped with automatic
control and computer-assisted data processing facilities, is
used for determining the so-called sodium expansion, ther-
mal linear expansion coefficient (TLEC), for measuring ther-
mal expansion, compression, shrinkage, elastic modulus, and
compressive strength of refractory lining materials.
Sodium expansion. Test unit 1 in the IK-4 test complex is
used to determine the linear sodium expansion of the hearth
and wall blocks during electrolysis (Rapoport test). The com
ponents of the test unit are: an electric furnace for heating the
test specimen and electrolyte; a mechanism for lifting and
letting down the furnace; a loading device to apply a constant
pressure (from 1 to 10 MPa) to the specimen; conductors to
carry current to the specimen and crucible. To prevent oxida
tion of the material of specimen and crucible, the electrolysis
is carried out under argon.
The sodium expansion test for the carbon-graphite lining
includes the following operations:
— preparing cylindrical specimens of diameter 30 mm
and length 100 mm;
— preparing an electrolyte with a cryolite ratio of
3 ± 0.05 and composition (wt.%): Na
, 86.0 (658 g);
, 5.0 (38 g); Al
, 9.0 (69 g);
— drying the specimen, crucible, and alundum disk at
100°C for 3 h;
— placing a graphite crucible with the specimen and
electrolyte in an electric furnace;
— applying a load of 1 MPa to the specimen;
— heating to 980 ± 10°C and holding until a steady-
state regime is attained;
— performing electrolysis for 2 h at a current density of
, with the measured data stored in a computer and
graphically displayed on the screen;
— plotting the sodium expansion diagrams.
Temperature expansion. Test unit 3 of the IK-4 test com-
plex serves to measure the expansion of the “green” hearth
mix (on heating from room temperature to 950°C) and the
TLEC of lining materials. It is composed of an electric fur
nace, a heat insulator, a quartz retort, a quartz measuring rod,
a displacement sensor, and a fume hood.
Methodology for measuring the temperature expansion
of the lining involved the following operation:
— preparing cylindrical specimens of diameter and
length 50 mm;
— placing a retort with the specimen and measuring rod
in the furnace;
— heating the hearth mix specimen to 950°C at a rate of
200°C/h and holding time of 2 h; to measure TLEC, the
heating rate is 200°C/h up to 520°C (when needed, to
950°C) and holding time 2 h;
— processing data on a computer and displaying results.
Elastic modulus and compressive strength. Test speci
mens of diameter 40 mm and length 50 mm are prepared.
Device 4 in the IK-4 test complex has a steel cup in which
the test specimen is accomodated. To protect the specimen
from oxidation, the cup is filled with graphite powder. The
cup is placed in an electric furnace, which is mounted on the
tensile testing machine; three measuring rods and a displace
Refractories and Industrial Ceramics Vol. 45, No. 5, 2004
1083-4877/04/4505-0336 © 2004 Springer Science + Business Media, Inc.
Engineering and Technology Center JSC; Élter Science and Tech
nology Center JSC, Russia.