A NEW RAW MATERIAL FOR ALUMINOSILICATE CERAMICS
FOR REFRACTORY AND ENGINEERING USE
T. V. Vakalova,
V. M. Pogrebenkov,
and O. A. Chernousova
Translated from Ogneupory i Tekhnicheskaya Keramika, Nos.7–8,pp.54–57,July – August, 2002.
Topaz-containing raw materials from the Kopna deposit are analyzed for chemical and mineral composition.
Beneficiated rocks with different contents of topaz and topaz concentrates are classified as commercially
promising for the manufacture of aluminosilicate refractories such as heat insulators and general-purpose
products. The role of topaz in the quality improvement of clay-topaz compositions and processes of sintering
and phase formation is discussed.
A major challenge in modern ceramic technology is de-
velopment of competitive products using traditional raw ma-
terials as well as the search for new starting materials of
promising commercial value.
In recent years, topaz, a fluoroaluminosilicate of natural
occurrence, has received an ever-increasing amount of atten-
tion from researchers for a number of reasons. First, topaz
when subjected to thermolysis yields acicular mullite that
can be used as the reinforcing material for ceramic matrix,
which improves the thermomechanical properties of engi
neering components. Second, the gaseous fluoride com
pounds released during degradation of the topaz structure are
of interest as mineralizers for ceramic mixtures [1 – 3].
In Russia, the discovery of gold – quartz – topaz rocks in
the Kopna deposit (Kemerovo Region) has heightened the
interest in topaz. The raw material, treated for separation of
gold by flotation, contains topaz and quartz concentrates and
a quartz-topaz product with a variable quartz-to-topaz ratio
that are of interest for a range of silicate technologies, in par
ticular, for production of aluminosilicate ceramics.
Rather extensive studies were carried out to see the po
tential use of the topaz concentrate as a component of high-
alumina refractories; it was found to be effective as a fine-
grain addition to the mixture and as the main component in
the fabrication of lightweight products .
In this work, topaz-containing rocks from the Kopna de
posit were used.
In five of the samples examined (samples T1 – T5),
quartz was compositionally predominant over topaz, and the
corresponding rocks were classified as topaz-depleted. By
contrast, in sample T6 topaz was the predominant species; it
was a finely dispersed product (with a grain size smaller than
0.088 mm) from a topaz rock dressed by flotation (Tables 1
Thus, the chemical and material composition of topaz
rocks rich in quartz from the Kopna deposit is an important
factor in the phase composition, properties and, conse-
quently, the kind of commercial aluminosilicate ceramics.
As is known, a disadvantage of chamotte-based ladle and
general-purpose refractories prepared from the classical alu
minosilicate compositions is the rather low compressive
strength because of the poor sinterability of the clay bond at
Refractories and Industrial Ceramics Vol. 43, Nos.7–8, 2002
1083-4877/02/0708-0277$27.00 © 2002 Plenum Publishing Corporation
Tomsk Polytechnical University, Tomsk, Russia.
TABLE 1. Chemical Composition of Raw Materials
CaO MgO R
T1 92.80 3.43 1.20 0.71 0.51 – 1.35
T2 85.14 8.29 0.56 0.67 0.95 – 4.59
T3 82.94 10.20 0.79 0.70 0.10 – 5.27
T4 79.97 11.20 0.79 0.60 1.40 – 6.04
T5 75.94 15.70 0.37 0.20 0.70 – 7.49
T6 59.65 26.25 0.35 0.10 1.31 – 12.34
TD clay 49.63 36.16 2.52 0.95 1.3 0.52 8.93
Chamotte 54.44 39.67 2.76 1.04 1.43 0.57 –
Topaz rocks calcined at 1350°C; argillaceous rocks — at 1000°C.