PRODUCTION OF FOAMED VERMICULITE FROM CONGLOMERATES
IN MODULAR-POURING ELECTRIC FURNACES
A. I. Nizhegorodov
Translated from Novye Ogneupory, No. 1, pp. 12 – 16, January, 2016.
Original article submitted May 19, 2015.
A technology for firing vermiculite conglomerates with a high content of inert material is examined. The fir
ing operation is completed in an additional “zero” module by the internal heat accumulated in the conglomer
ate itself. Heat is transferred by radiation from particles of the inert material to the vermiculite granules inside
the conglomerate. At the same time, heat is being transferred by conduction from the outer layers of the gran
ules to their inner layers. Such a method of using recuperated heat makes it possible to mitigate the tempera
ture regime of the electric modules, reduce the consumption of electric power, and decrease the energy content
of the process.
Keywords: electric modular-pouring furnace, vermiculite, inert material, energy of heat assimilation, second-
ary energy resources (SERs), heat radiation, “zero” module, furnace efficiency.
Foamed vermiculite remains a product that is in demand,
it being a raw material that is used to make a wide range of
refractory, fire-protective, temperature-resistant, and heat-in-
sulating materials and products. In addition to vermiculite
concentrates, technogenic wastes from tailings repositories
that are formed in the processing of vermiculite ores also
serve as a raw material for obtaining foamed vermiculite.
The use of technogenic mineral-based raw materials is
known to be effective in many cases and is comparable in
terms of economic indices to the processing of commercial
minerals obtained directly by the mining of natural deposits.
Such raw materials are less costly to acquire, refine, and pre
pare for processing, and their industrial processing reduces
the costs incurred in maintaining waste banks and tailings re
positories . Hundreds of thousands of tons of such
so-called “wet” tailings have been accumulated just at the
Kovdor deposit. The weight content of vermiculite in differ
ent fractions of these tailings normally ranges up to 27% and
in certain cases reaches 52% . After suitable preparation,
conglomerates of grades KVP-1 and KVP-2 could be
shipped to customers of the Kovdor Mining-Concentration
Combine. However, there has not been a significant demand
for these materials due to the lack of an energy-efficient tech-
nology for processing them.
New modular-pouring electric furnaces with a heat-recu-
peration system can solve this problem with minimal energy
costs [3, 4]. The goals of studies that were performed were
first to analyze the process of the absorption of heat energy
by conglomerates containing different amounts of inert mate
rial. Another goal was to study the completion of the firing of
vermiculite in a “zero” module. The firing is completed by
the internal heat radiated onto vermiculite particles by parti
cles of an inert material at the same time that heat is being
transferred by conduction within the vermiculite from the
outer layers to the inner layers. Yet another goal of the stud
ies was to design an energy-efficient furnace which operates
at lower temperatures and consumes less electric power than
Figure 1 presents a block diagram of the production of
foamed vermiculite from conglomerates and rough-dressed
concentrates that contain from 6 to 73% inert material. The
raw material is sent by elevator from the warehouse to the
batcher of the modular-pouring electric furnace. After the fir
ing operation, the material is aerodynamically separated into
light and heavy fractions and stored in the appropriate hop
pers. Figure 2 presents a sketch of a three-module furnace.
The furnace is equipped with a unit for aerodynamic separa
Refractories and Industrial Ceramics Vol. 57, No. 1, May, 2016
1083-4877/16/05701-0013 © 2016 Springer Science+Business Media New York
Irkutsk National Research Technical University, Irkutsk, Russia.