DISPERSITY OF THE FERRIFEROUS CHROME SPINELID
AND COMPOSITION OF THE FILLER AS FACTORS
AFFECTING THE FORMATION OF STRUCTURE IN REFRACTORIES
S. A. Suvorov
and T. V. Yarushina
Translated from Novye Ogneupory, No. 7, July, 2004, pp. 37 – 40.
Original article submitted May 28, 2004.
Physicomechanical properties of periclase-spinelid ceramics, in particular, the softening temperature under
load and compressive strength, are shown to be controlled by the granular composition of the native
ferriferous chrome spinelid. At relatively low concentration of CaO (0.51 – 0.88 wt.%), SiO
1.33 wt.%), and ratio CaO/SiO
= 0.38 – 1.36, the incipient deformation temperature under load does not
It has been shown in  that the Chrome ore of peri-
clase-spinelid composition (recovered from the Bushveld
Complex, Republic of South Africa) is a promising material
for production of refractory components. Refractories based
on this ore and tested for service in the slag zone and in the
upper section of an argon-oxygen steel refining unit showed
a thermal durability not inferior to that of refractory compo-
nents available from foreign manufacturers. The precursor
materials were ferriferous chrome spinelid (fractions
<0.5 mm), fused periclase chromite (8.0 – 10.0% Cr
filler, and vibroground fused periclase as a dispersant.
As is well known, the granular composition of precursor
materials is a central factor that controls the rate of reaction
in the solid phase. According to Yander’s classical theory
, the rate of a solid-phase reaction is controlled by the
grain size (particle radius) of the reactants irrespective of
their composition. Obviously, the grain size of as-recovered
chrome spinelid is a factor that plays a role in the buildup of
periclase spinelid refractories. Still, the effect of composition
on the solid-phase reaction and, finally, on the properties of
refractories remains a debatable issue.
The formation of structure in periclase-spinelid refracto
ries during high-temperature sintering was studied on speci
mens of a natural ferriferous chrome spinelid of different
dispersity. The precursor material was beneficated chrome
ore from the Republic of South Africa, of composition
(wt.%): MgO, 9.61 – 9.75; SiO
, 0.75 – 0.88; Al
, 13.3 –
, 28.7 – 28.8 (FeO, 17.2 – 18.3 included); Cr
47.4 – 47.9; CaO, 0.00 – 0.08; Äm
In the first run of experiments, the filler was fused peri-
clase chromite of size fraction <3 mm and Cr
tion of 8 – 19%; the dispersant was vibroground fused peri-
clase and ground fused periclase and chrome spinelid mixed
in a ratio of 40:60. Chrome spinelid (15%) was added to the
mixture as size fractions of 2 – 0.5, 0.5 – 0, and <0.063 mm.
The granular filler was 70 – 75%, and the finely dispersed
fraction was 25 – 30%. The overall granular composition
was the same in all mixtures. The components were molded
under a pressure of 160 MPa, dried in air, and sintered in a
tunnel furnace. The holding time at maximum temperature
(1800 – 1850°C) was 6 h. Relevant data are given in Table 1.
In the second run of experiments, the effect of mixture
composition on the formation of structure in the refractory
materials was studied. The filler was fused periclase chro
mite of size fraction <3 mm and Cr
mass fraction of
8 – 20%; the dispersant was vibroground fused periclase and
ground fused periclase and chrome spinelid mixed in a ratio
of 90:10. Chrome spinelid (5%) was added to the mixture as
size fractions of 2 – 0.5, 0.5 – 0, and <0.063 mm. The granu
lar filler was 70 – 75%, and the finely dispersed fraction was
25 – 30%. Conditions for carrying out tests in the two runs of
experiments were identical.
One will note (Table 1) the presence of dispersed peri
clase in specimens 1, 2, 4, and 5, and a finely dispersed mix
Refractories and Industrial Ceramics Vol. 45, No. 5, 2004
1083-4877/04/4505-0352 © 2004 Springer Science + Business Media, Inc.
St. Petersburg State Technological Institute (Technical Univer
sity), St. Petersburg, Russia; Kombinat Magnezit Joint-Stock Co.,
Satka, Chelyabinskaya Oblast’, Russia.