USING SELF-DEGRADABLE MAGNESIA PELLETS IN SLAG SPLASHING
TECHNOLOGY FOR PROTECTION OF THE CONVERTER LINING
K. N. Demidov,
V. G. Ovsyannikov,
O. F. Shatilov,
V. F. D’yachenko,
T. V. Borisova,
and O. B. Voronina
Translated from Novye Ogneupory, No. 1, pp. 15 – 17, January, 2005.
Original article submitted November 13, 2004.
Results of industrial tests carried out on self-degradable magnesia pellets (SMP) of different composition for
use in the slag splashing technology for protection of the oxygen converter’s refractory lining are reported.
A technology known as slag splashing has gained wide-
spread acceptance around the world as an effective tool for
increasing the durability of the refractory lining in oxygen
converters. This technique has been used by foreign manu-
facturers (for example, Nippon Steel Corporation (Japan),
LTV Steel Corporation (U.S.), or EkoStahl (Germany) and
domestic enterprises [Magnitogorsk Iron and Steel Works
(ISW) JSC, Nizhny Tagil ISW JSC, Severstal’ JSC, ZapSib
(West Siberia ISW) JSC]. A durability of the refractory lin-
ing as high as 15,658 heats (for a 252-ton converter) has
been reported from the LTV Steel Corporation, and
14,001 heats — from the Bao Steel Co. (China).
MISW JSC, according to average data reported in 2003, the
durability of the refractory lining (available from a domestic
manufacturer) was 3757 heats.
Currently, raw dolomite (a MgO-containing material) is
used in the nitrogen-blown splashing technology for oxygen
converters. However, the slag treated by this technology un
dergoes rapid cooling, and because of the low MgO content
(17 – 20%) and high CaO content (about 30%) in dolomite,
the uptake of magnesium oxide by slag is far from optimum.
The Ural Institute for Metals JSC in cooperation with the
Kombinat Magnezit JSC has developed a range of fluxes
containing 45 – 65% MgO at a calcination loss Dm
25 – 50%. These fluxes are commercially available as pellets
made up of the precursor material using a disk pelletizer.
The pellets when introduced into a high-temperature oxi-
dized slag prior to, or during, the nitrogen-assisted splashing
undergo self-decomposition. The self-degradable magnesia
pellets (SMPs) are composed of 70 – 85% magnesite MgCO
and brucite Mg(OH)
; these, when heated to 400 – 700°C,
decompose to yield a highly dispersed and chemically active
magnesia which is readily absorbed by the slag. Pellets high
in MgO and low in CaO provide conditions for saturation of
the slag with magnesium oxide and decrease in the low-melt
ing calcium ferrites, and the addition of carbon to pellets
(SMP-5S, SMP-10S, or SMP-15S) reduces the slag
oxidability. Dehydration of brucite and decarbonization of
magnesite are endothermal reactions, which causes the tem
perature of slag to decrease and its viscosity to increase.
-containing pellets produces a dual effect on
the protecting slag coating (the scull): the MgO fraction in
the slag increases, and additional components — magnesio
Refractories and Industrial Ceramics Vol. 46, No. 3, 2005
1083-4877/05/4603-0157 © 2005 Springer Science+Business Media, Inc.
Ural Institute of Metals Joint-Stock Co., Ekaterinburg, Russia;
Magnitogorsk Iron and Steel Works (MISW) Joint-Stock Co.,
Magnitogorsk, Russia; Kombinat Magnezit JSC, Satka, Chelya
binsk Region, Russia.
“Slag splashing technique in the oxygen-converter steelmaking at
the Bao Steel. A crystallography structure analysis of the slag,”
I&SM, pp.1–4,July (2000).
TABLE 1. Results in the Determination of SMP Dissolution Rate
Content, % Pellet
SMP-10S 9.6 – 12.6 2.3 25 0.092
SMP-1 – – 12.5 2.5 35 0.071
SMP-10 – 11 13.0 2.6 40 0.065
8.6 11.3 12.7 2.4 50 0.048