EXPERIENCE OF USING MONOBLOCK STOPPERS
WITH A MAGNESIA HEAD SECTION
A. A. Korostelev,
N. S. S’emshchikov,
A. A. Chernyshev,
A. E. Semin,
K. N. Bel’maz,
A. N. Bozheskov,
V. V. Kazakov,
and A. V. Kosonogov
Translated from Novye Ogneupory,No.6,pp.3–7,June, 2016.
Original article submitted April 11, 2016.
Monoblock stoppers of different quality in metallurgical enterprises are analyzed and the effect of stopper ma
terial on metal pouring stability in a CBCM is demonstrated.
Keywords: steel castability, channel closing, monoblock stopper, nonmetallic inclusions, metal level in
A monoblock stopper is an important part of a CBCM
tundish providing dispensed delivery of steel into a
crystallizer, and shutting off the nozzle-dispenser channel in
the case of a production requirement . Precise calculation
of monoblock stopper head geometry and choice of the re-
quired material quality is extremely important from the point
of view of metal dispensing stability over a prolonged pe-
During steel pouring the most vulnerable area of a stop-
per is its head subject to mechanical wear and chemical ero
sion. Therefore traditionally a stopper head is made from
stronger material. In order to manufacture the stopper head
the material used is based on magnesium oxide, graphite, and
carbon binder, or base on aluminum oxide, graphite, and car
bon binder. Both materials are entirely compatible with ma
terials of the stopper main body and therefore they are
Stoppers with a head made of material based on Al
exhibit greater strength in bending at ambient temperature
(about 9 MPa) compared with these properties of material
based on MgO (about 7 MPa). However, at the stopper tem
peratures used the advantage in material strength of corun
dum-graphite composition disappears, and resistance is de-
termined by chemical composition of the steel being poured.
A reduction in the life of a corundum-graphite stopper head
is particularly significant in pouring steel deoxidized with
calcium-containing materials . Therefore with a prolonged
series of steel melts treated with calcium preference is given
to monoblock stoppers with a head made of material based
on magnesium oxide. It should be noted that production of
stoppers that may withstand loads with high mass flow rates
requires hi-tech equipment and availability of high quality
magnesia raw material, and also use of efficient methods for
protecting carbon from oxidation both during object opera
tion and its manufacture (during heat treatment). Of magne
sia-carbon object properties special importance applies to
good mechanical strength at elevated temperature and resis
tance to chemical erosion [3 – 5]. This is connected with
high refractoriness of periclase, presence of an effective car
bon matrix, secured with introduction of combined antioxi
dant additives. The greatest disadvantage of magnesia-car
bon objects is sensitivity to internal mechanical stresses,
caused predominantly by thermal shock. However, this fac
tor is easily overcome due sustained fulfilment of re
commendations for warming up objects before the start of
In contemporary steel smelting production extra-furnace
treatment calcium-containing materials are an integral part of
the technology and occupy a leading position in view of the
multifactored nature of the effect of calcium on physico
chemical condition of a melt and metal product quality and
properties . Melt treatment with calcium-containing mate
Refractories and Industrial Ceramics Vol. 57, No. 3, September, 2016
1083-4877/16/05703-0224 © 2016 Springer Science+Business Media New York
Proceedings of the International Conference of Refractory
Workers and Metallurgists (7 – 8 April, 2016, Moscow).
OOO VPO Stal’, Obninsk, Moscow Region, Russia.
FGAOU VPO NITU MISiS, Moscow, Russia.
Corwintec Europe Ltd, Dalian, China.
OAO Volga Pipe Plant, Volzhskii, Russia.
AO OMK-Stal’, Vyksa, Russia.