DEVELOPMENT AND STUDY OF THE COMPOSITIONS
OF UNSHAPED FIRECLAY-BASED HEAT-INSULATING REFRACTORIES
AND A TECHNOLOGY FOR MAKING THEM
N. A. Peretokina
and V. A. Doroganov
Translated from Novye Ogneupory, No. 2, pp. 27 – 29, February 2011.
Original article submitted October 1, 2009.
Results are presented from a study of the compositions of foams for making heat-insulating refractory prod-
ucts with the use of a slag-alkali binder. It is shown that use of the given binder can yield materials with an ulti-
mate compressive strength of up to 20 – 22 MPa. These materials can be used as heat-insulating materials and
as structural materials.
Keywords: heat-insulating refractories, heat-insulating products, slag-alkali binder, frothing method, foam.
With the rapid progress being made in the development
of technologies that intensify thermal processes while saving
energy resources, recent years have seen an increasing focus
on the creation of new high-efficiency heat-insulating mate-
rials for equipment used in power generation, oil refining,
and metallurgy. These materials must satisfy diverse and
sometimes conflicting requirements: on the one hand, they
should reduce conductive heat flow in the structures that they
are being used to protect; on the other hand, they should also
have structural properties which will ensure a long service
life for the thermal equipment as a whole. Only by satisfying
both of these needs can the optimum effect be obtained from
using materials of the given type.
Different bonding agents are currently being used as
binders in the production of heat-insulating materials. In the
view of the authors, one of the most promising trends is the
use of inorganic chemical binders. This class of materials in-
cludes slag-alkali binders. The slag-alkali component in-
creases the plastic strength of the product and allows rapid
removal of the forms used to make products by foam tech-
nology. Slags with the necessary activity must be used to en-
sure a short turnaround time for the forms, reduce shrinkage,
and ensure that the resulting thermal insulation is of high
Clay of grade LT-1from the Latnensk deposit,
vibro-milled fireclay (35 – 40% Al
), sodium silicate, and
slag from the Oskol’sk Electrometallurgical Combine
(OEMK) that has undergone dry cooling in air are presently
used as the raw materials. The OEMK slag is mechanically
activated by crushing it in a “Sand-1” planetary ball mill
equipped with 10-mm-diam. balls and rotating at a speed of
roughly 200 min
. Fractions of slag finer than 0.315 mm are
used in the production process. Data obtained from x-ray
phase analysis shows that the main phase in the slag is
dicalcium silicate g-2CaO·SiO
. The slag also contains he-
matite, ferrous oxide, and periclase. The clay in the Latnensk
deposit is a kaolin clay and contains a negligible amount of
quartz. The vibro-milled fireclay is a finely dispersed powder
which consists of particles smaller than 0.315 mm and also
contains mullite and crystoballite.
The frothing agent that was used was “Piner-152,” which
is a homogeneous transparent liquid ranging in color from
light yellow to brown. The agent has a density of
1000 – 1200 kg/m
at 20 – 25°C and has the pH 7.0 – 10.0.
The expansion ratio of the foam formed from a working so-
lution containing 3 vol.% of the frothing agent is less than
7.0. The stability of the foam is at least 360 sec. The compo-
sitions of the foams used in the studies being discussed here
are shown in Table 1.
The heat-insulating products were made by the method
traditionally used  to obtain foamed ceramics, i.e. by mix-
ing a previously prepared foam based on a surfactant and a
mineral component (vibro-milled fireclay, slag, slip from
Latnensk clay, and sodium silicate). The specimens (cubes
with sides of 50 mm) were cast in metal molds pre-coated
with oil. The specimens were kept in the molds for 1 day.
Then the molds were partially dismantled and the specimens
were left in them for another 24 h before being placed in a
Refractories and Industrial Ceramics Vol. 52, No. 1, May, 2011
1083-4877/11/05201-0052 © 2011 Springer Science+Business Media, Inc.
Belgorod State Technological University, Belgorod, Russia.