THE EFFECT OF TEMPERATURE ON THE LINING
OF ROTARY CEMENT KILNS
V. I. Shubin
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 4, pp. 40 – 47, April, 2001.
Achievements in the study of thermal effects on the lining of rotary cement kilns, both at home and abroad, are
reviewed. In particular, thermal expansion of the lining and the thermal mechanical stresses associated there
with are considered.
There is a range of factors that are responsible for the oc
currence of thermomechanical stresses in the lining of a ro
tary kiln. The stresses arise because of the thermal expansion
of the ring brickwork housed inside the stiff cylindrical shell
or because of the nonstationary heat conditions of the kiln’s
operation. They may also arise because of the thermal shocks
associated with the failure of the protective skull (lining slag)
built up from the material calcined.
STRESSES ARISING BECAUSE
OF THE THERMAL EXPANSION
OF THE LINING IN THE CYLINDRICAL
METAL SHELL OF THE KILN CASING
On heating, the lining expands proportional to the ther
mal linear expansion coefficient (TCLE) of the refractory
and to the temperature. Graphically, the TCLE as a function
of the temperature for a number of magnesia and fireclay
refractories and skulls is shown in Fig. 1. Magnesia refrac
tories used for lining the hot zone (sintering zone) of rotary
kilns have the highest values of TCLE. The kiln lining is sub
jected to compressive stress since, when heated, its tempera
ture is somewhat higher than the temperature of the kiln cas
ing. The lining is tightly held against the casing by means of
brick wedges and stemming materials.
For example, with a magnesia-spinel lining 250 mm
thick in a rotary kiln with a diameter of 5.6 m heated to
1420°C, the brickwork in the free state should expand by
42.84 mm . However, under these conditions, the kiln cas
ing attains a temperature of 320°C and expands by a mere
10.08 mm and thus impedes free expansion of the lining. The
resulting effect of this mismatch is the generation of tensile
stress in the kiln casing and, correspondingly, of compressive
stress in the lining.
G. Weibel  considered thermal stresses in the refrac-
tory lining and the kiln casing and arrived at the conclusion
that, in a first approximation, the stresses can be treated by
is the compressive stress, MPa, a is the thermal
linear expansion coefficient, K
, Dn is the temperature dif-
ference, °C, and E
is the modulus of elasticity, kN/mm
Refractories and Industrial Ceramics Vol. 42, Nos.3–4, 2001
1083-4877/01/0304-0171$25.00 © 2001 Plenum Publishing Corporation
The previous article in the series was published in No. 3 of 2001.
NIItsement Research Institute Joint-Stock Company, St. Peter
– 6 – 1
Fig. 1. Thermal linear expansion coefficient a for magnesia-spinel
and fireclay refractories and for clinker skull plotted as a function
of temperature: 1 ) periclase-spinel refractory; 2 ) porous skull;
3 ) dense skull; refractory materials: 4 ) periclase-chrome; 5 ) peri
clase-spinel; 6 ) chrome-periclase; 7 ) fireclay.