SCIENTIFIC RESEARCH AND DEVELOPMENTS
THERMOMECHANICAL PROCESSES IN THE PRODUCTION
OF MINERAL FIBERS
I. M. Fedotkin
and A. G. Novitskii
Translated from Novye Ogneupory, No. 6, pp. 50 – 53, June, 2003.
A theoretical model for thermomechanical processes in high-temperature gas-blown mineral fiber technology
has been developed and its use for engineering analysis of rational production regimes is demonstrated. Ways
of updating the fiber buildup nozzle assembly are suggested. A differential equation for description of the
model is derived and a method for its solution is given.
Heat insulation and fire protection have been and continue
to be issues of immediate concern in the strategy of global
economy of energy resources. Fibers made from basalt rocks
belong to a widely used type of heat-insulating materials.
Basalt fibers constitute the base for a wide range of
heat-insulating and sound-proof materials with an apparent
density of 20 to 200 kg/m
, heat conductivity of 0.0279 to
0.0337 W/(m × K) (at 0°C), and sound absorption coefficient
of 0.8 to 0.98 (at frequencies 200 – 1800 Hz), such as
broached matts, rolled materials, plates, cardboard, cords,
etc.; filter materials (thick basalt fiber cloths with a filtration
factor of 0.58 to 0.93 cm/sec, filters for cleaning and steri
lization of air and gas media with a filtration factor of 0.681
to 0.912 cm/sec); structural and reinforced materials (plain
and shaped basalt plastic sheets, tubes, fibers, rolled and
packaged basalt-fibrous reinforced frameworks, etc.) .
Currently, blowing and drawing techniques using high-
speed flows of hot air or gases have found application in the
production of secondary mineral and polymer fibers. The gas
blowing of glass or basalt fibers is effected using high-tem
perature flows of gas products generated in combustion
chambers. During the gas blowing and drawing treatment,
the primary fiber fed into the blow nozzle from a die (duplex
process) is subjected to friction forces of the gas against the
fiber surface, which facilitates the fiber drawing. Simulta
neously, an intense heat exchange between the flowing gas
and the fiber takes place, because of which the fibers take up
heat and their viscoelastic properties deteriorate .
In what follows, we present results of a theoretical study
of the thermomechanical processes involved in the gas blow-
ing of fibers and their potential application for the engineer-
ing analysis of optimum operational regimes in the produc-
tion of mineral fibers. The major requirements placed on the
quality of mineral fibers are sufficiently high mechanical
strength, minimum amount of nonfibrous inclusions, maxi-
mum possible fineness, and homogeneity at minimum ener
gy expenditures. To reach a high production level, updating
of the actual equipment is required. Unfortunately, the du
plex process is energy-intensive, which presents a serious
obstacle to its further development; however, at present it is
the only realistic technological route towards obtaining
high-quality gas-blown mineral fibers.
We consider a mathematical model to describe the heat
ing of a mineral filament drawn in a flow of hot gas (gas
blowing of mineral fibers).
Conditions for the buildup of a secondary fiber from the
primary filament are schematically shown in Fig. 1.
The heat balance in the control unit volume dV = Fdx is
Input – Output = 0.
+ f (x )l
na(x ) ´ 2pr (x )dx – f (x )G
Dividing by dx and substituting f (x )=pr
(x ) and
Refractories and Industrial Ceramics Vol. 45, No. 4, 2004
1083-4877/04/4504-0242 © 2004 Springer Science+Business Media, Inc.
National Technical University of Ukraine (KPI), Kiev, Ukraine.