INCREASED LIFE FOR OPEN-HEARTH FURNACE ROOF LINING
V. V. Slovikovskii
and A. V. Gulyaeva
Translated from Novye Ogneupory,No.8,pp.7–9,August, 2013.
Original article submitted November 12, 2012.
Reasons are studied for the short life of sprung-suspended roofs of open-hearth furnaces and refractory objects
are developed with reduced thermal conductivity and a special hook. During refractory laying a shrinkage-free
high-temperature laying mortar is used. OAO Nizhnyi Tagil’ Metallurgical Combine organizes industrial out
put of the refractories developed. Industrial testing is carried out in open-hearth furnace arched roofs of OAO
Nizhnyi Tagil’ Metallurgical Combine (NTMK) and ZAO Nizhnyi Sergi Metalware and Metallurgical Plant
(NMMZ). According to test results the increase in roof life is 20 – 30%, and the economic effect for two
open-hearth furnaces is 4,656 million rubles per year.
Keywords: refractory object spalling, sprung-suspended roof, special refractory object with reduced thermal
conductivity, laying mortar, arched roof.
The life of an open-hearth furnace lining is governed by
that of the roof lining, as the most rapidly worn area of a lin-
ing. For example, in the Nizhnyi Sergi Metalware and Metal-
lurgical Plant (N. Sergi) the lining service life for two
open-hearth furnaces is from 150 to 160 days, which leads to
furnace downtime for thirty days in order to carry out expen-
sive cold lining repair.
In the RF sprung-suspended roof structures of
open-hearth furnaces are most widespread, combining sus
pension, preventing sagging, and restrictors preventing
upwarping. Features of the structure are reinforcement with
pins for all refractory objects of each roof ring, and rein
forcement with metal plates (Fig. 1).
Abroad special attention is devoted to the quality of sus
pender plates. The chromium content within them is
20 – 25%, nickel 4 – 8%. In the RF there is no extensive ex
perience of using heat-resistant plates. With an increase in
open-hearth operating intensity, particularly with use of oxy
gen, cases are observed of rapid heating and breakage of sus
pender plates, which leads to premature stoppage of a fur
nace for repair with greater roof residual thickness.
Premature wear also occurs due to spalling of roof re
fractory objects. Spalling is a predominant form of wear,
caused by thermal shock during roof cooling and warm-up,
during charge loading, during hearth hot repair, and also dur
ing intermediate cold repair of a furnace hearth. Normally
refractories wear rapidly in individual areas of a roof. Static
stability is lost as a result of local wear of some roof arches.
Less warm parts settle, and warmer parts lift. As a result of
this a roof operating at the start of a campaign has a thrust
roof and in the second half starts to serve as a suspended
Refractories and Industrial Ceramics Vol. 54, No. 4, November, 2013
1083-4877/13/05404-0272 © 2013 Springer Science+Business Media New York
FGAOU VPO Ural Federal University, Ekaterinburg, Russia.
Fig. 1. Longitudinal section of roof suspender fastening: 1 ) tie-rod;
2 ) wedge; 3 ) channel; 4 ) supporting arch; 5 ) packing; 6 ) collar;
7 ) tube; 8 ) suspended plate; 9 ) bolt; 10 ) angle irons; 11 ) pin;
12 ) brick.