USE OF MAGNESIAN-DOLOMITE MIXTURES IN STEEL-MELTING
FURNACE HEARTHS AND THE MECHANISM OF THEIR WEAR
IN SERVICE. 1. STUDY OF JEHEARTH REFRACTORY MIXTURE
T. I. Shchekina,
E. N. Gramenitskii,
A. M. Batanova,
T. A. Kurbyko,
A. V. Likhodievskii,
B. N. Grigor’ev,
A. N. Pyrikov,
and R. Gazhur
Translated from Novye Ogneupory, No. 12, pp. 31 – 41, December, 2006.
Original article submitted August 23, 2006.
The results of mineralogical-petrographic analysis of Jehearth magnesian-dolomite refractory mixture used in
the hearths of steel-melting furnaces are described. The variation regularities of its phase and chemical com
position are identified and the mechanism of its wear in service at the metallurgical works in Russia is con
The present study is the continuation of the preceding
paper  and focuses on the refractory material Jehearth pro-
duced by the Slovakian Magnesite Works and used in the
hearths of open-hearth furnaces at the Vyksunskii Metallur-
gical Works. We have also investigated the initial material,
namely magnesian-dolomite mixture of grade Jehearth
30BA. Materials were studied using the methods of optical
and electron microscopy, microprobe, silicate, and x-ray
phase analysis described in .
RESULTS OF INVESTIGATION AND DISCUSSION
The initial refractory mixture Jehearth 30 BA (sample
M22) used in the post-blow zone of an open-hearth furnace
has the form of a gray powder with a yellowish tint and pre
vailing particle size < 0.5 mm; the lateral size of 0.5 – 1.5 mm
is observed in less than 30% particles. Around 7% of the
mixture is represented by aggregate fragments or “lumps” of
rounded or slightly elongated shape and size up to 10 mm.
The largest of these fragments have a flattened shape resem
bling shingle. Petrographic analysis identifies these frag
ments as a typical granoblastic structure formed by isometric
periclase grains of size ranging from 0.04 to 0.2 mm with
rare pores of length 0.1 mm. The periclase grains have a he
xagonal section with slightly rounded angles. According to
the probe analysis data, periclase contains 4% wustite com
ponent with traces of Si, Al, Mn, Ca, K, and P. The inter-
stices contain bands of size up to 0.1 – 0.3 mm identified as
bicalcium silicate and a spinel-like phase whose composition
is close to calcium ferrite.
The chemical composition of the initial refractory differs
from its specifications  by a higher content (within
0.5 – 2 wt.%) of SiO
, and CaO and a lower content
of MgO and FeO + Fe
(Table 1). Iron exists in the initial
refractory mainly as the trivalent form. The CaO/SiO ratio
found by silicate analysis is 1.7 times lower than the specifi
cations data, due to a higher content of SiO
According to the norm (Table 1) of the initial material,
the quantitative ratio of its phases is as follows (mol.%):
periclase 90.5, bicalcium silicate 2.1, bicalcium ferrite 5.4,
and CaO 2.0.
Variations occurring in refractory Jehearth 30BA in ser
vice were studied on the basis of two samples taken from dif
ferent parts of the furnace hearth: from the front bank at the
level of the slag belt near the middle blow zone (M34) and
from the back bank (M2).
Sample M34 of size 100 ´ 80 ´ 60 mm is monolithic and
has a zonal structure. The sintered part of the sample, which
is the remotest from the site of contact with molten metal and
slag (over 55 mm), which is classified as the least altered
zone 1, has a light gray color with a yellowish shade and a
brecciated structure. The prevailing fragments are elongated
light-colored yellowish periclase fragments of length from 1
to 5 mm cemented by a close-grained (0.03 – 0.15 mm) bind
ing (main) mixture with a granoblastic structure (Fig. 1a ).
The fragment edges are frequently decorated by metal iron
Refractories and Industrial Ceramics Vol. 47, No. 6, 2006
1083-4877/06/4706-0363 © 2006 Springer Science+Business Media, Inc.
Lomonosov Moscow State University, “OgneuporTreidGrup”
Slovakian Magnesite Works, Slovakia.