GRAIN SIZE COMPOSITION AND POROUS STRUCTURE OF CARBON
HEARTH BLOCK MATERIALS FOR ALUMINUM ELECTROLYZERS
A. L. Yurkov,
S. A. Khramenko,
and Yu. M. Mosin
Translated from Novye Ogneupory, No. 5, pp. 26 – 30, May 2010.
Original article submitted March 19, 2010.
Results are provided for the design of a carbon refractory structure with a pore size of less than 25 mm. It is es
tablished that if in planning the charge for carbon blocks the coarse fraction (10 – 5 mm) is excluded, convert
ing the medium and fine fractions to 100%, then the sizes of fractions become close to those calculated by
equations used traditionally describing optimum particle packing. In a three-fraction charge carbon material
compositions composites are obtained within which the predominant pore size is less than 25 or even 10 mm.
Keywords: carbon hearth blocks, polyfraction grain size composition, pore size.
The material considered is a continuation of the cycle of
articles for evaluating the characteristics of carbon hearth
blocks for aluminum electrolyzers [1, 2] it has been shown
that the size of permeable pores is a critical property of the
structure of blocks from the point of view their service life.
This conclusion was drawn on the basis of simulating move-
ment of electrolyte through permeable pores of hearth blocks
and was confirmed by experimental observations.
In hearth blocks with a pore size of 25 ± 5 mm the rate of
electrolyte movement though permeable pores is determined
by the rate of movement of the temperature front of the elec
trolyte liquidus. After 96 – 100 h electrolyte reaction with
aluminosilicate refractory commences, there is formation
“lenses” of reaction products, raising of blocks, and break
In hearth blocks with pore diameters less than the critical
value the rate of electrolyte filtration is less than the rate of
the liquidus movement front. Electrolyte crystallizes in pores
of the carbon refractory; reaction of electrolyte and alumino
silicate refractory occurs over many months after the start of
The composition and properties considered in this publi
cation are for carbon hearth blocks that were used perform
ing an industrial experiment. The properties of hearth block
materials are provided in Table 1; for comparison specifica
tions are also shown for hearth blocks in accordance with TU
1913-109-021–2003 “Carbon hearth blocks for aluminum
ANALYSIS OF THE GRAIN SIZE COMPOSITION
OF CHARGE MIXES FOR CARBON
In carbon refractory technology (Fig. 1) the producers
implement different preparation schemes for molding mixes.
– as a rule a screen is used with two to three sieving
grids; it is possible for anisotropically drawn out particles to
pass through the screen (that is typical for anthracite) and
screening accuracy does not exceed 80%;
– the fine fraction is a product of grinding in a ball mill
of a fraction finer than 0.5 mm in order to obtain not less
than 80% fraction finer that 0.075 mm;
Refractories and Industrial Ceramics Vol. 51, No. 3, 2010
1083-4877/10/5103-0172 © 2010 Springer Science+Business Media, Inc.
OAO Volga Abrasive Plant, Vol’skii, Volgograd Region, Russia.
Siberian Federal University, Krasnoyarsk, Russia.
D. I. Mendeleev RKhTU, Moscow, Russia.
Fig. 1. Carbon hearth block structure.