EFFECT OF THE ADDITION OF ELECTROCORUNDUM
ON STRUCTURAL-PHASE TRANSFORMATIONS IN THE QUARTZ LINING
OF AN INDUSTRIAL-FREQUENCY CRUCIBLE-TYPE
V. A. Kukartsev,
A. M. Sazonov,
V. G. Babkin,
and P. A. Tishin
Translated from Novye Ogneupory, No. 3. pp. 108 – 112, March, 2015.
Original article submitted January 14, 2015.
Results are presented from studies of the phase interactions that take place between the metal, lining, slag, and
gas inside the lining of an industrial-frequency crucible-type induction furnace (CIF). The lining is composed
of quartzite, boric acid, and electrocorundum. The phase composition of the lining is determined. The lining
lasted 295 heats in the production of ferrous-metal alloys at temperatures up to 1570°C. The chemical and
phase compositions of the slag-covered layer and the sintered layer of the lining are also determined.
Keywords: industrial-frequency crucible-type induction furnace (CIF), quartzite, lining region, scanning
electron microscopy (SEM), x-ray phase analysis (XPA).
Industrial-frequency crucible-type induction furnaces
(CIF) with an acid lining first began to be actively used to
mak cast iron in the USSR during the 1970s. In accordance
with the requirements of the designers of these furnaces, the
cast iron was made from a cold metallic charge composed of
foundry iron, conversion iron, recycled cast iron, the liquid
residue left in the furnace (1/3 of its capacity), and pig-iron
and steel scrap. The scrap content of the charge was roughly
10 – 15%. The temperature at which the charge was melted
was limited to 1450°C. Higher temperatures were not re
quired for a charge of the composition just described and the
lining lasted 250 – 350 heats. These operating conditions
were also in keeping with the recommendations of the fur
nace manufacturers. Today, the content of steel scrap in the
metallic cold charge used at many foundries is 70 – 80%.
Accordingly, the temperature regime during the production
process is more demanding and the service life of the furnace
lining has declined significantly.
The durability of the lining in the production of iron al
loys is appreciably affected by the high-temperature reac
tions that take place and involve the participation of gaseous,
metallic,, and slag phases. The role of reactions involving
metallic and gas phases in the production of steel in furnaces
with an acid lining was first studied by V. V. Lapin in 1936
. The scientist observed the migration of oxides in the
used dinas brick that was employed to make the roof of elec-
tric-arc furnaces. This migration led to the formation of three
different zones. The first zone after the slag layer was gray in
color and was composed of cristobalite. The black second
zone consisted of tridymite, while the third zone was still
comprised of nearly unaltered brick. It was also determined
that oxides of iron and manganese accumulated in the
tridymite zone and that oxides of calcium, aluminum, and ti
tanium accumulated in the transitional zone. The least-
changed zone had a residual quartzite content of 11%. It was
also established that the cristobalite zone contained 81.6%
cristobalite and 18.4% of a glassy phase composed of
iron-manganese monticellite and magnetite.
In 1966, a detailed description was published of the met
allurgical processes which take place during the production
of synthetic cast iron in industrial-frequency induction fur
naces with an acid lining. Study of the interactions of the dif
ferent phases (metal, lining, slag, and gas) determined that
slag is formed and reacts with the lining, the components of
the alloy undergo oxidation, and the silicon which is present
may undergo reduction by the carbon in the metallic melt.
This process is strongly affected by the porosity of the lining
which is formed as the quartzite is sintered with boric acid.
Refractories and Industrial Ceramics Vol. 56, No. 2, July, 2015
1083-4877/15/05602-0151 © 2015 Springer Science+Business Media New York
Siberian Federal University, Krasnoyarsk, Russia.
Tomsk State National Research University, Tomsk, Russia.