EFFECT OF PARAMETERS OF STATE ON PHASE TRANSITIONS
OF CARBONIZED PERICLASE REFRACTORIES
S. A. Suvorov,
V. A. Musevich,
F. R. Iksanov,
and A. A. Slobodov
Translated from Novye Ogneupory, No. 10, pp. 44 – 50, October 2007.
Original article submitted July 5, 2007.
Thermodynamic physicochemical modelling and calculation methods are used to study the effect of tempera
ture on phase and chemical transitions in the system MgO–C–Al–Al
at 298 – 2400 K applied to the behavior of carbonized periclase refractories under production and
operating conditions. Partial and total pressure, developed by gaseous reaction products of material with an
average pore space (CO
, CO, CH
, etc.) are determined in relation to pressure. The effect of gasifi
cation for the carbon component, porosity, original and atmospheric moisture, that is not currently subject to
experimental observation, are considered.
Experimental scientific and industrial studies of periclase
carbon-containing refractories with all the apparent require-
ments for performing them and the importance of their re-
sults [1 – 3] do not provide comprehensive information about
interconnected phase and chemical transitions that occur suc-
cessively and in parallel under conditions of external loads:
temperature, composition and gas atmosphere volume, etc.
Traditional thermodynamic analysis of individual reac-
tions and phase transitions [4 – 6] also does not provide valu-
able reliable representation of the physicochemical changes
in complex systems. In contrast, an approach based on sys
tem analysis using contemporary model and calculation de
vices of chemical thermodynamics demonstrates it prospects
and efficiency [7, 8].
Results in  have stimulated further consideration of
the problem of physicochemical and applied significance,
particularly important for understanding and monitoring
during heat treatment (293 – 573 K), carbonizing firing
(573 – 1273 K), and operation of periclase carbon-containing
refractories (1273 – 2400 K).
The thermal stability of phases is normally studied at a
fixed pressure (often the standard equal to 0.1 MPa). For
conditions of the occurrence of chemical reactions in the
pore space of a refractory not only are isobaric conditions
important but also isochoric (constancy of volume) condi
tions. The first are typical for surface layers and the second
are typical for the pore space with a refractory isolated from
the surrounding atmosphere. Under high temperature condi-
tions the pressure in pores may markedly increase, and there-
fore material behavior in these two cases may be markedly
different. Consideration of the combined problem of deter-
mining the effect of temperature on pressure in pore space
also has a very important practical component: development
of a filtration counterpressure for melts of slag and metal that
markedly affect refractory breakdown. The study in  of in
teraction of periclase carbon-containing refractories with the
surrounding atmosphere was performed under conditions
controlled by high temperatures during operation when the
most stable of its phases are periclase, carbon and com
pounds accompanying them.
Work in  was devoted to determining the dependence
on temperature of the concentration of gaseous products de
veloping pressure (partial or total) of material reaction with
the atmosphere of the pore space (CO
, CO, CH
etc.), the effect on gasification of the carbon component, po
rosity, original and atmospheric moisture, that are not cur
rently subject to direct experimental observation.
Under heat treatment conditions periclase-carbon raw
material, in the period between operation and with possible
uncontrolled output from a unit, when the temperature varies
from 298 to 2400 K, phase and chemical transitions occur.
A combined study of them is important for precise represen
tation of transitions of the phase composition of periclase-
Refractories and Industrial Ceramics Vol. 48, No. 5, 2007
1083-4877/07/4805-0362 © 2007 Springer Science+Business Media, Inc.
St. Petersburg State Institute of Technology (Technical Univer
Sources of water in condensed and vapor states are not only natu
ral water of the ingredients and atmospheric air, but also poly
condensation of resins, oxidation of organic substances, etc.