OPEN-HEARTH FURNACE STEEL MELTING
BATH REFRACTORY SERVICING
V. A. Startsev,
G. V. Voronov,
L. I. Kaplun,
V. A. Panevkin,
and E. A. Vasin
Translated from Novye Ogneupory, No. 6, pp. 7 – 10, June 2010.
Original article submitted March 19, 2010.
The reliability of a steel-melting object operation depends to a considerable extent on the state of the furnace
hearth refractory lining. Prolonged and partial furnace stoppages lead to loss of integrity of the sintered layer
whose restoration requires performance of several necessary operations. Timely repair of the sintered layer re
duces hot lost time and periclase material consumption.
Keywords: furnace, hearth, chamotte objects, periclase objects, sintered layer, melting, beam, metal sheet,
temperature, infra-red imager, wall.
The hearth is one of the main elements of the workspace
of an open-hearth furnace. It consists of a bottom, within
whose central part there is steel delivery opening, longitudi-
nal banks over the side of the furnace and transverse in the
direction of the front and rear walls. During operation of a
hearth it should exhibit sufficient impact strength in order to
withstand mechanical damage during loading with charges of
categories A and B of form No. 1 – 3 (GOST 2787), and also
physicochemical action of a gas atmosphere, slag and metal,
hydrodynamic action of poured molten iron, delivered steel,
etc. The lining of the hearth should be of rational thickness in
order to provide sufficient heat insulation and reliable resis
tance to possible penetration of liquid metal.
Normally a hearth consists of successively placed layers
of refractory material, laid on a metal sheet. The first layer is
asbestos board (GOST 2850). A layer chamotte objects
(GOST 8693) is placed upon it, and then there is a layer of
periclase powder, that is the so-called sintered layer. The de
sign thickness of the furnace hearth with a capacity of
200 – 300 tons is 1080 – 1170 mm, including, mm: sintered
layer 225 – 250, layer of periclase objects 690 – 805,
chamotte 120, asbestos board about 20 . Laying of the
bottom, longitudinal and transverse banks is also made with
horizontal rows. The slope of the hearth bottom surface in
the direction of the steel-pouring opening is made due to the
sintered layer to a value of 0.05. The axis of the steel-pouring
opening is arranged at an angle of 7° to the horizontal sur-
face. Transverse banks of the hearth of the rear and front
walls to the level of the charging doors is made at an angle of
45°, and the longitudinal banks from the direction of the port
are made at an angle of about 35°. Expansion joints are filled
with periclase powder grade DMPK-75 with a gap.
Thermal expansion joints in the hearth periclase layer
have a thickness of 10 mm per running meter with laying on
end and 4.5 – 6.0 mm with laying at the edge. Thermal ex
pansion joints are not considered in the layer of chamotte ob
jects in laying the bottom and banks. In rows of periclase ob
jects in the longitudinal bank from the direction of the port
the thermal expansion joints are 9 mm per 1 running meter of
laying. Joints are staggered in the banks.
The temperature of the inner surface of the hearth during
melting varies within wide limits. On direct contact with
molten metal before delivery its rises to 1660°C and on con
tact with the slag to 1700°C. In the period of repairing banks
and the hearth bottom the temperature falls below 1000°C.
The heat resistance of the lining should provide a tempera
ture of the outer surface of the hearth metal sheet not above
150°C (PB 11-493–02, GOST 12.2.099, ). In open-hearth
furnaces with a capacity of 60, 270 and 450 tons the cycle of
temperature measurements of the surface of the metal sheet
was carried out using an IR-imager grade
SAT-90G. Repeated temperature measurements of the
hearth metal sheet surface were carried out when the furnace
was in a steady-state operating regime. Analysis of the re
Refractories and Industrial Ceramics Vol. 51, No. 3, 2010
1083-4877/10/5103-0142 © 2010 Springer Science+Business Media, Inc.
GOUVPO UGTU-UPI, Ekaterinburg, Russia.
OOO Independent Electrical Company, Ekaterinburg, Russia.
OAO Chusovoi Metallurgical Plant, Chusovoi, Perm Region,