FEATURES OF SOLID PHASE SYNTHESIS OF WOLLASTONITE
FROM NATURAL AND TECHNOGENIC RAW MATERIAL
T. V. Vakalova,
N. P. Karionova,
V. M. Pogrebenkov,
V. I. Vereshchagin,
and V. V. Gorbatenko
Translated from Novye Ogneupory, No. 8, pp. 36 – 42, August 2010.
Original article submitted March 29, 2010.
Solid phase synthesis of wollastonite based on natural (diatomite, opoka, marshallite) and technogenic
(microsilica, and anhydrous silicic acid) silica raw material is studied. A definite effect is established for the
nature of silica raw material on wollastonite synthesis in the range 1000 – 1200°C. The most complete synthe
sis occurs with use of finely dispersed amorphous silica, in the form of microsilica, independent of the nature
of the calcium-containing component.
Keywords: silica raw material, carbonate raw material, wollastonite, synthesis, solid-phase reaction, struc
Until recently production of refractory materials and re-
fractory fittings within Russia was aimed mainly at ferrous
metallurgy, since it is assumed that the stringent service con-
ditions in ferrous metallurgy certainly satisfies the service in-
dices, required in nonferrous metallurgy where the tempera-
ture level and corrosiveness of melts is lower. However, in
the majority of cases potential possibilities for these
refractories in nonferrous metallurgy enterprises are not en
tirely realised. At the same time many overseas firms are
concerned with development of refractories for nonferrous
metallurgy, including for the aluminum industry, taking ac
count of the specific operation of linings in the correspond
ing furnaces. Within Russia production of special refractories
for aluminum electrolyzers has been poorly developed, in
spite of the fact that problems of lining life and reduction of
specific consumption of refractories and electrical energy is
Domestic and overseas practical experience shows that
the main ceramic materials for preparing aluminum are alu
minosilicate refractories, diatomite objects, objects based on
calcium silicate, etc. Here of particular importance is cal
cium silicate ceramic with a wollastonite crystalline phase
due to its high mechanical property indices, low thermal con
ductivity, high thermal shock resistance, etc.
Natural wollastonite, in view of features of its chemical
and mineral composition and physical properties (improved
jointing, acicular-fibrous habit of particles, whiteness, chem
ical inertness, etc.), is a promising raw material for a whole
series of branches of the national economy. Considerable at-
tention is also drawn to artificial wollastonite, obtained by
firing a mixture calcium- and silicon-containing components.
In properties this wollastonite is almost identical to natural
wollastonite, and in some indices it even surpasses it.
Known methods for synthesizing wollastonite are very
varied: hydrothermal synthesis [1, 2], solid-phase reaction in
the presence of a liquid phase , crystallization from a melt,
dehydration of hydrosilicates, etc. Of particular scientific
and practical interest is solid-phase synthesis of wollastonite
by ceramic technology from a mixture of silica and calcare
ous raw material of natural and technogenic origin.
In nature and technical products silica raw material is en
countered both in amorphous and crystalline states, that un
doubtedly points to its activity in synthesizing silicate mate
rials. Therefore of this work was to study the effect of struc
ture and phase features of the starting raw materials on
solid-phase synthesis of wollastonite.
The silica raw materials used for synthesizing
wollastonite were natural rocks in the from of diatomite and
opoka of the Inzensk deposit (Ul’yanov region), marshallite
of the Ebashev deposit (Novosibirsk region), and also
technogenic products, i.e. chemically pure anhydrous silicic
acid and microsilica, that is waste from the production of
crystalline silicon and ferrosilicon of OAO Novokuznetsk
Ferroalloy Plant. Complete properties of the starting raw ma
terials and the structure and phase changes during heating
have been considered in .
Refractories and Industrial Ceramics Vol. 51, No. 4, 2010
1083-4877/10/5104-0295 © 2010 Springer Science+Business Media, Inc.
National Research Tomsk Polytechnic University, Tomsk, Russia.