PRODUCTION OF HEAT-INSULATING DIATOMITE ARTICLES
BY A PLASTIC METHOD OF MOLDING
I. D. Kashcheev,
K. G. Zemlyanoi,
E. A. Nikiforov,
A. B. Klimovskii,
and S. A. Nesterova
Translated from Novye Ogneupory, No. 2, pp. 22 – 28, February, 2010.
Original article submitted September 29, 2010.
The basic technological parameters of the process of molding by means of extrusion of diatomic articles at
OOO Diatomitovye Kombinat are determined, in particular, the composition of the charge, methods of prepa
ration of the charge, and the molding and heat processing regimes. It is shown that addition of chalk to the
charge increases the working temperature to 1200°C and improves the physico-chemical indicators of the
properties of the resulting articles.
Keywords: diatomite, additive, charge, plastic compaction, plasticity, strength, thermal conduction
Results of an industrial laboratory production of heat-in-
sulating articles based on diatomite from the Inza deposit
were presented in a previous report . It was shown that
plastic molding with the addition of chalk and sawdust to the
charge should be used to manufacture articles with apparent
density in the range 0.8 – 1.0 g/cm
A plastic method of molding of diatomite articles with
the addition of sawdust has been set forth in a number of
published studies [2 – 4]. The firm of Skamol (Denmark)
produces heat-insulating articles based on diatomite and
fuel-depleting agents with different levels of apparent den
sity, with the basic parameters of the articles corresponding
to the quality indicators of articles manufactured by OOO
Diatomovyi Kombinat (Inza).
A mass which is to be used for molding by means of
plastic molding must be plastic, i.e., capable of varying its
shape under the pressure of external forces without any break
in continuity or the formation of cracks and thixotropy, i.e., it
must preserve a new shape following the cessation of the ac
tion of these forces. Of the many factors that exert an influ
ence on the plastic state of matter, we wish to note internal
and external friction, coalescence of particles, adhesion, elas
ticity, and other factors [5 – 8], all of which induce the ap
pearance of defects in connection with the irregular move
ment of matter, that is, the difference in the rate of flow of
matter at the corners of the press neck and in the central part
of the rod (“dragon tooth,” “knot”).
Montmorillonite clay imparts plastic properties to diato-
mite; the content of this clay in diatomite from the Inza de-
posit is around 10 wt.%. Montmorillonite is prone to swell-
ing once it has been moistered with water, which produces
high plasticity in the mass.
A plastic method of production requires careful treatment
of the mass, thus preliminary mixing together with moisten-
ing and repeated treatment of the mass in an auger extruder
(clay cutter), in particular, with intermediate aging .
The rheological properties of a plastic mass and the na
ture of its flow through the neck of an auger extruder vary
upon the addition of components to the charge that increase
the working temperature of diatomite articles to 1100 – 1150°C
(refractory clay, alumina-, and calcium-containing minerals).
Thus, the addition of clay increases the coherence and
strength of the mass but reduces its degree of thixotropy (the
mass accumulates “wet” strength more slowly and is more
easily deformed). Alumina-containing substances increase
the coherence and strength of a mass and render it more rigid
and harder to work. Calcium-containing masses increase the
plasticity and coherence of a mass and increase its degree of
thixotropy, but render it more sensitive to the content of tem
pering water. In the case of plastic molding of diatomite arti
cles, sawdust behaves as a reinforcing agent, increasing the
elasticity and coherence of a mass and, to some degree, im
proving its moldability.
With this in mind, optimization of the composition of a
charge has been performed experimentally under production
conditions at the pilot plant sector of OOO Diatomovye
Refractories and Industrial Ceramics Vol. 51, No. 1, 2010
1083-4877/10/5101-0018 © 2010 Springer Science+Business Media, Inc.
GOUVPO UGTU-UPI, Ekaterinburg, Russia.
OOO PIK Diatomit-invest, Ul’yanovsk, Russia.
OOO NT-Ts, Ul’yanovsk, Russia.