REFRACTORIES IN HEATING UNITS
FORMATION OF MAGNESIA SLAGS OF SENSIBLE COMPOSITION
WITH CONVERTER PROCESSING OF HIGH-PHOSPHORUS CAST IRON
AND APPLICATION OF A WEAR-RESISTANT SLAG SKULL
TO A LINING USING A MAGNESIA-ALUMINA FLUX
K. N. Demidov,
M. F. Vitushchenko,
L. A. Smirnov,
A. N. Zolin,
A. A. Babenko,
V. I. Bogomyakov,
A. P. Vozchikov,
V. I. Yablonskii,
A. A. Dobromilov,
T. V. Borisova,
D. E. Firsov,
L. Yu. Krivykh,
and Kh. Sh. Kutdusova
Translated from Novye Ogneupory,No.1,pp.3–5,January, 2013.
Original article submitted May 25, 2012.
Processes are considered for conversion of high-phosphorus cast iron during steel smelting in 300-ton oxygen
converters of AO Arselormittal Temirtau beneath magnesia slags of sensible composition. Technology is de-
veloped and assimilated, including application towards the end of blowing with oxygen of saturated magnesia
slag (8 – 11% MgO) with basicity 3.0 – 3.4 and formation of a wear-resistant skull coating (with resistance of
1 – 2 melts) on the lining during slag blowing with high-pressure nitrogen with additions of magnesia alumina
flux (MAF). Use of MAF flux provides an increase in slag MgO content (up to 9 – 10%) with maintenance of
required metal dephosphorizing within the limits 97.1 – 98.1% with a phosphorus content in metal on average
of 0.013 – 0.017%.
Keywords: oxygen converter, high-phosphorus cast iron conversion, slag saturation with magnesium oxide,
magnesia alumina flux (MAF), slag skull, dephosphorization.
Under conditions of the AO Arselormittal Temirtau, Ka
zakhstan Republic, converter workshop in converting cast
iron with a high phosphorus content (from 0.5 to 0.8%) tech
nology has been assimilated for smelting in 300-ton convert
ers under magnesia fluxes of sensible composition, formed
by addition of magnesia-alumina flux (MAF). At the start of
research converter lining life was 1800 – 2000 melts. The
magnesia addition used is mainly fired and raw dolomite,
and also dolomitized lime, whose addition did not provide
formation of saturated magnesia slags. In addition, as a result
of a shortage of fired dolomite 30% of melts were carried out
without adding it.
Formation at the end of blowing of phosphorus conver
sion converter slags, containing 6.4 – 7.2% MgO with basic
ity 3.4 – 3.9, included 30 – 40% high-temperature phase, i.e.,
calcium silicophosphate with a melting temperature of
2100 – 2200°C. However, due to presence within the slag of
a high proportion of ferruginous calcium oxide (10 – 20%)
and readily melting calcium ferrites (35 – 42%), fulfilling the
role of a cementing binder between high-temperature phases,
the life of the converter skull formed on the converter lining
was less than one melt.
It has been established that treating phosphorus cast iron
by processes including slag skimming, in order to form final
magnesia slags in the range of MgO saturation with use of
fired dolomite it is necessary to add MgO in addition in an
amount of 0.8 – 1.8 tons, which it is proposed to supply us
ing MAF containing 76 – 82% MgO, 4 – 8% Fe
, less than 5% (CaO + SiO
), with addition of it during
slag blowing with nitrogen and in the concluding period of
blowing a melt after intermediate slag skimming. It is recom
mended to establish basicity of final slag
(SiO ) + (P O )
not more than 3.5.
Refractories and Industrial Ceramics Vol. 54, No. 1, May, 2013
1083-4877/13/05401-0001 © 2013 Springer Science+Business Media New York
From proceedings of the International Conference of Refractory
Workers and Metallurgists (29 – 30 March, 2012, Moscow).
OAO Ural Institute of Metals, Ekaterinburg, Russia.
AO Arselormittal Temirtau, Kazakhstan Republic.