COMPREHENSIVE SOLUTION FOR LINING THE SOCLE
OF AN ELECTROLYZER WITH CONTEMPORARY REFRACTORIES
AND HEAT INSULATING MATERIALS
V. Ya. Sakulin,
V. V. Skurikhin,
V. P. Migal’,
and A. P. Margishvili
Translated from Novye Ogneupory, No. 3, pp. 99 – 107, March, 2007.
Original article submitted November 1, 2006.
OAO Borovichi Refractory Plant has developed a number of new forms of product for lining the socle of an
electrolyzer for obtaining primary aluminium. Results are provided for research on thermal insulating vermi
culite products of the ITOM (integral heat insulation refractory materials) series and barrier materials: dense
fired refractory articles BorAluBar, mastic for filling joints BorAluPlast, and dry barrier mixture BorAluMix.
Newly developed products will make it possible to propose to aluminum producers a comprehensive solution
for lining the electrolyzer cathode with contemporary refractories and thermal insulating materials with a high
technical resource. Use of the materials will make it possible to prolong electrolyzer service life by several
Aluminum is prepared by electrolysis of alumina dis-
solved in molten cryolite at 940 – 970°C (the Héroult-Hall
method). The service life of an electrolyzer for aluminum
production is governed to a considerable extent by the
service life of the cathode unit whose lining layout is pre-
sented in Fig. 1 . The high temperature of the process
gives rise to a high corrosion rate for refractory materials of
the socle lining. In order to search for methods for protecting
them it is necessary to clarify the mechanism of electrolyzer
cathode unit breakdown for which first it is necessary to give
characteristics of the corrosive medium acting on the refrac-
CORROSIVE MEDIUM CHARACTERISTICS
The main components of the electrolyte are cryolite
, aluminum fluoride AlF
, and alumina Al
components of the electrolyte reach the refractory lining
during capillary flow in pores of the hearth carbon blocks
through cracks of opening joints and hearth continuity de
fects. Fluorine salts within the electrolyte have different vo
latility. It follows from calculated data  that the most vola
tile at the temperature of the process is sodium tetra
Sodium is a subsidiary product of electrolysis during alu
minum production. Having a low boiling temperature (892°C)
and being a surface active metal with respect to aluminum
, during bath operation sodium enters the surroundings,
including the cathode blocks and refractory materials, and it
enters into chemical reaction with them.
REFRACTORY MATERIAL CHARACTERISTICS
Oxides of tin, nickel, iron and zinc that have almost no
reaction with sodium and aluminum fluorides could be
chemically effect barriers against molten cryolite, but their
Refractories and Industrial Ceramics Vol. 48, No. 1, 2007
1083-4877/07/4801-0026 © 2007 Springer Science+Business Media, Inc.
Joint Stock Company (OAO) Borovichi Refractory Plant, Russia.
Fig. 1. Layout of an aluminum electrolyzer cathode unit lining:
1, cathode carbon blocks; 2, aluminum current carrier (bloom);
3, current carrier insulation; 4, layer of dry barrier mixture; 5, bar
rier layer (fireclay product); 6, heat insulating layer (foam diatomite
products); 7, cathode steel casing.