REFRACTORIES IN HEAT UNITS
UPDATING THE CIRCULATING VACUUM DEGASSING TECHNOLOGY
AT THE MAGNITOGORSK IRON AND STEEL WORKS JOINT-STOCK CO.
Yu. A. Bodyaev,
E. V. Burmistrova,
V. G. Ovsyannikov,
V. I. Frolov,
S. A. Samoilin,
and I. M. Shatokhin
Translated from Novye Ogneupory, No. 4, pp.6–8,April, 2003.
Updating of a unit for outside-the-furnace vacuum degassing intended for the preparation of a low-carbon
(£ 0.004% C) IF-steel is described. The updating involved replacement of the electric heater for the work
space with a gas-oxygen burner. Changes in the refractory lining wear rate associated with this replacement
are discussed. Routes towards further improvement of the vacuum degassing technology are outlined.
In 2001, a program to modernize units for outside-the-
furnace vacuum degassing of steel was launched at the
Magnitogorsk Iron and Steel Works (MISW) Joint-Stock Co.
The main goal was organization of the production of cold-
rolled zinc-coated automobile body sheet of ultra-low carbon
IF-grade steel (with carbon not exceeding 0.004%).
Earlier, imported refractory materials for the bottom lin
ing of circulating vacuum degassers were tested and put in
service. Since that time, stability of the lining for RH-bot
toms has increased appreciably, with an increased contribu
tion to the overall campaign. The wear rate of the lining for
fitting pipes decreased as well as the number of emergency
shutdowns (Table 1).
In step 1, the heating system of the work space of the
vacuum chamber was reconstructed. The electric arc heater
was replaced by a gas-oxygen burner that was positioned up-
right along the chamber axis in the arch of the hot-gas duct.
The gas-oxygen burner is used not only to reheat the repaired
lining; it serves also to supply oxygen for metal decarbu-
rizing during preparation of a low-carbon steel.
To update the oxygen-blow vacuum degassing techno-
logy, common steels with carbon content of 0.04 – 0.05%
were initially used; however, their processing led to metal
overoxidation and, consequently, to a high consumption of
aluminum during deoxidation. The undesired overoxidation
could be avoided using precursor steels with a higher carbon
content (in excess of 0.08%), which made it possible to ob
tain low-carbon steels (£ 0.003%) by blowing oxygen during
Based on tentative test data, a relationship between the
carbon concentration and oxygen blowing regime (time and
gas flow rate) was established.
Refractories and Industrial Ceramics Vol. 45, No. 3, 2004
1083-4877/04/4503-0147 © 2004 Plenum Publishing Corporation
Magnitogorsk Iron and Steel Works (MISW) Joint-Stock Co.,
TABLE 1. Trends in the Steel Processing Using Outside-the-Furnace Vacuum Degassing Units Under RH Regime Conditions
2000 2001 2002
Average stability of the bottom lining in circulating vacuum degassers,
heats (maximum number of heats shown in brackets) 112 (1029) 109 (148) 147 (175)
Number of campaigns conducted in RH regime (against the total annual), % 41 42 89
Number of emergency shutdown campaigns associated with the lining failure, % 43 40 12