MODERN METHODS OF RECYCLING PENT POTLININGS
FROM ELECTROLYSIS BATHS USED IN ALUMINUM PRODUCTION
V. Yu. Bazhin
and R. K. Patrin
Translated from Novye Ogneupory, No. 2, pp. 39 – 41, February, 2011.
Original article submitted December 24, 2010.
This article discusses the problem of recycling wastes in the form of spent refractories and heat-insulating ma-
terials in the lining of electrolysis baths used to produce aluminum. The environmental effects of fluorocar-
bons in the cathode lining are evaluated, and a survey is made of methods that can be used to recycle wastes
generated in aluminum production.
Keywords: aluminum electrolysis; refractory and heat-insulating materials; spent potlining from an alumi-
num electrolysis bath.
The increase in aluminum production worldwide has also
increased the amount of solid wastes being generated in the
form of spent lining materials. These wastes include car-
bon-graphite and silicon-carbide blocks and various grades
of refractory and thermal insulating products. According to
expert appraisals , the amount of spent lining material cre-
ated in the operation of electrolysis cells used to make alumi-
num increases by 1.7 million tons every year. Its disposal
adds to the size of existing dumps, which already contain
more than ten million of tons of such wastes.
Electrothermal and electrochemical processes that take
place during the electrolysis of aluminum cause irreversible
structural changes in the refractories and thermal insulating
materials of the cathode and lead to the formation of cracks.
As a result, the electrolysis bath must be overhauled and the
spent lining completely replaced every 3 – 5 yrs [2 – 4]. The
lining materials, saturated with fluorides and sodium, form
compounds characterized by a complex composition and dis-
tribution which depend on the operating parameters of the
bath and the properties of the original materials [4, 5]. Figure
1 shows the fracture of the carbon-graphite lining of the bot-
tom of an electrolytic bath, while Fig. 2 shows the conse-
quences from penetration of the area under the hearth blocks
by the metal and the electrolyte. It can be seen from the pho-
tograph that fractures were formed and that sintering of the
Refractories and Industrial Ceramics Vol. 52, No. 1, May, 2011
1083-4877/11/05201-0063 © 2011 Springer Science+Business Media, Inc.
G. V. Plekhanov St. Petersburg State Mining Institute, St. Peters
Fig. 2. Fracture of the heat-insulating refractory lining of the side of
Fig. 1. Fracture of the bottom of an electrolysis bath.