EXPERIMENTAL STUDY OF PHYSICOCHEMICAL PROCESSES
DURING FIRING OF ACID-RESISTANT MATERIALS
BASED ON TRADITIONAL NATURAL MATERIALS
AND PRODUCTION WASTES
E. S. Abdrakhimova,
V. Z. Abdrakhimov,
I. Yu. Roshchupkina,
and Yu. B. Myshentseva
Translated from Novye Ogneupory, No. 1, pp. 45 – 51, January, 2012.
Original article submitted February 17, 2011.
Features are established for the occurrence of thermal processes, making it possible to control them, and use
the data obtained in developing ceramic acid-resistant material firing regimes. The least coefficient of effec
tive thermal conductivity of acid-resistant materials lies in a temperature range within which the intensity of
physicochemical processes is more marked. These zones correspond to the most complex firing conditions,
since the lower thermal conductivity, the slower an object heats up.
Keywords: firing, physicochemical processes, temperature, acid-resistant material, argillaceous part of zir-
con-ilmenite ore gravitation tailings (ZIG), kaolin, pyrophyllite, high-alumina petrochemical wastes, thermal
diffusivity, thermodynamics, differential heating curves.
During heating at different temperatures in acid-resistant
materials there are a number of complex physicochemical
phenomena causing a change in their properties. In the range
0 – 150°C there is raw material drying. There is formation of
a significant amount water vapor, which with a rapid increase
in temperature is released too quickly and that may break an
object [1 – 3].
In the range from 150 to 1000 – 1050°C (before mullite
formation) in acid-resistant materials based on argillaceous
clay of zircon-ilmenite ore gravitation tailings (ZIG), and ka
olin clay, there is dehydration, i.e., removal of chemically
bonded water, within the composition of argillaceous sub
stance and other minerals [1 – 3]. There is a breakdown in
material crystal lattice, clays minerals and an argillaceous
component lose ductility properties. This period of heating,
including a breakdown of carbonates and modification
changes of quartz, is safe with respect to the first interval.
Removal of chemically bonded water starts from approxi
mately 350°C, and removal of the main mass of this water is
observed at 450 – 500°C and may continue up to 900°C (if
the clay component contains montmorillonite (1 – 3). There
is object shrinkage and a reduction in mechanical strength.
At 300 – 450°C the volatile part of organic impurities of ar-
gillaceous components is liberated.
With a rapid increase in temperature in the range
300 – 500°C there is strong liberation of gaseous combustion
products, which prevents penetration of oxygen into an
acid-resistant material, and a reducing atmosphere occurs
within it, which is indicated by darkness in the fracture of
fired objects [1 – 3].
A fundamental possibility was demonstrated in [4 – 9] of
using ZIG, kaolin clay of the Chapaevsk deposit, pyro
phyllite and high-alumina petrochemical wastes, i.e. ex
hausted catalyst IM-2201 from the Novokuibyshev Petro
chemical Plant, in the production of acid-resistant materials,
The chemical composition of the test raw material compo
nents is presented in Table 1.
In order to study the physicochemical processes during
firing of acid-resistant refractories materials of two composi
tions are used, presented in Table 2, from which plates with a
size of 100 ´ 100 ´ 20 mm were prepared by plastic mold
Refractories and Industrial Ceramics Vol. 53, No. 1, May, 2012
1083-4877/12/05301-0040 © 2012 Springer Science+Business Media, Inc.
S. B. Korolev Samara State Aerospace University (National Re
search University), Samara, Russia.
AMOUVPO Samara Academy of State and Municipal Manage
ment, Samara, Russia.