STATE OF THE ART AND TRENDS IN THE DEVELOPMENT
OF BASE PLATE MATERIALS FOR ALUMINUM ELECTROLYSIS CELLS
A. V. Proshkin
and D. A. Simakov
Translated from Novye Ogneupory, No. 2, pp. 16 – 22, February, 2005.
Original article submitted September 17, 2004.
The state of the art and trends in the production and application of barrier materials intended for preventing the
infiltration of corrosive components (sodium, sodium fluoride, and molten aluminum) into the heat-insulating
layer of refractories for the base plate of aluminum electrolysis cells are discussed. Results for different types
of barrier materials tested for cryolitic stability are given; the granular composition and pore structure of some
of them are studied. Strengths and weaknesses of the barrier materials are discussed.
The service life and other engineering and economic in-
dices of aluminum electrolysis cells depend to a large extent
on the cathode refractories used, in particular, barrier materi-
als which protect the heat-insulating section of the base plate
from corrosive attack.
Currently, a wide range of barrier materials are available
from various manufacturers; however, a material that would
meet all requirements (not infrequently conflicting) is yet to
be discovered. Judging from the recent literature [1 – 7], the
development, application, and behavior of these materials
continue to be issues of major concern.
In this paper, we report on the state of the art in the pro
duction and application of barrier materials, in particular
drawing mainly from the results of studies on the interaction
between aggressive components of the aluminum bath and
barrier materials that were conducted at the ETC JSC.
The barrier materials serve to prevent penetration of so
dium and fluoride salts through the porous structure of cath
ode blocks and interblock joints. Cathode blocks with a low
porosity (13 – 19%) prevent infiltration of liquid-phase fluo
ride salts. The velocity of advance of the front of interaction
between electrolyte components and refractory materials in
the central part of the base plate was observed to decrease
from 55 to 30 mm/day (based on data recorded over a ser
vice period of three months).
At low rates of interaction between electrolyte and re
fractory components, the temperature regime becomes stabi
lized, which extends the service life of the base plate. In con-
trast, under unstable temperature regimes, the liquidus iso-
therm tends to displace towards the lower section of the base
plate, which increases the risk of corrosive attack of reactive
electrolyte components on the barrier material in contact
with the heat insulation of the base plate. Be it so, the heat in-
sulation degrades its thermal and physical properties and
may even cause it to undergo deformation. The decrease in
thermal resistance of heat insulation makes the isotherm dis
place towards the upper section of the base plate; eventually,
this may result in the occurrence of “cakes” of the surface of
cathode blocks, with an improper current distribution and
crystallization defects throughout the bulk of the base plate.
The poor design of electrolysis cells, in particular the “too
warm” heat insulation, may stimulate these unfavorable pro
cesses. The aluminum production costs are to a significant
extent determined by the amount of the base plate materials
used, that is, purchase costs, installation costs, and storage
costs. Viewed in this light, the rational use of barrier materi
als may save costs in the production of primary aluminum.
The requirements placed on barrier materials can succinctly
formulated in the following manner:
high resistance to corrosive attack by sodium vapors,
molted fluorides, and (occasionally) molten aluminum;
fabricability and easy installation of lining materials;
economic efficiency of production, installation, and
maintenance of barrier materials;
stability of thermal and physical properties during the
service of electrolysis cells;
Refractories and Industrial Ceramics Vol. 46, No. 2, 2005
1083-4877/05/4602-0104 © 2005 Springer Science+Business Media, Inc.
Engineering and Technology Center (ETC) Joint-Stock Co.,