METHOD OF DETERMINING THE RESISTANCE
OF FURNACE REFRACTORIES TO SLAG AND CLINKER
L. M. Aksel’rod,
I. G. Maryasev,
and A. A. Platonov
Translated from Novye Ogneupory, No. 4, pp. 59 – 64, April, 2013.
Original article submitted January 10, 2013.
The “Magnezit” Group has developed a new method and equipment for testing the resistance of refractory
products to slag and clinker on rotary kilns. The method makes it possible to objectively evaluate the effec
tiveness of a given refractory as a lining material for equipment operating at high temperatures.
Keywords: refractories, slag resistance, clinker resistance, dynamic test method, rotary kiln.
The wear resistance of the lining of kilns depends on
many factors: the composition and structure of the
refractories that are used, the design and quality of the lining,
the geometric dimensions of the furnace, the technological
and heat-engineering regimes used to operate it, the compo-
sition of the charge being heated, and the formation and pres-
ervation of a protective covering (slag crust) . The adverse
effects of some of these factors — such as certain aspects the
design of the furnace, its geometric dimensions, and the
quality of the lining — can either be determined beforehand
or can be minimized by optimizing the furnace’s operating
regime . Other factors (the rate of crust formation and
chemical corrosion of the refractories) — factors for which
there is only “approximate” data on the physico-mechanical
characteristics of the corresponding refractories (chemical
composition — basic oxides; open porosity; ultimate com
pressive strength at room temperature; initial softening point;
heat resistance; residual changes in the dimensions at
1600°C) — can be evaluated only approximately and not al
ways accurately. Thus, we have developed a new method of
evaluating the service properties of refractories before they
are placed in service by the customer. The prototypes of the
new method are the “Rotary kiln test” (www.difk.de) and the
American standard .
The new procedure for studying the resistance of
refractories to clinker and slag was developed and introduced
in order to evaluate the character of the interaction between
the refractories and the charges in rotary kilns at the produc
tion facilities of the “Magnezit” Group. Tests are being con
ducted in a laboratory kiln equipped with an oxygen-gas
burner that ensures heating of the charge to 1700°C. The kiln
consists of two cylindrical parts: a stationary part affixed to
the guides of the rollers of the unit’s cooler; a removable part
designed to accommodate the test crucible. The cooler is
connected to an electric motor via a chain drive so as to make
it possible to smoothly change the speed of rotation of the
furnace over a sufficiently wide range — from 0.2 to 7 rpm.
The inside of the cooler is lined with heat-insulating products
and has a central hole 50 mm in diameter for removal of the
process gases and the insertion of a thermocouple. A plati-
num-rhodium thermocouple is used. The temperature con
troller connected to the thermocouple automatically records
the temperature regimes during the tests. Regulation of heat
ing rate and maintenance of the steady-state operating re
gimes are done manually.
The internal volume of the kiln is sufficient to hold a cru
cible comprised of 12 specimens. The refractory products
provided for the tests are used to prepare trapezoidal speci
mens with dimensions of 230 ´ (78/57) ´ 40 mm. The speci
mens are then assembled to form a single crucible consisting
of 12 segments. The joints in the crucible are either filled
with mortar or are formed dry. In the latter case, they are
dried at 110°C in a drying cabinet until their mass is con
stant. Each crucible must include at least one standard speci
men (made of a certain grade of refractory taken from a sin
gle batch in a large amount). Data on the clinker resistance of
the standard specimen is used to assess the feasibility of
comparing the results obtained in different tests.
Before the tests are begun, the concrete is placed in the
removable part of the laboratory kiln, the thermocouple is af
fixed to the kiln’s metal shell, and a gas burner is moved next
Refractories and Industrial Ceramics Vol. 54, No. 2, July, 2013
1083-4877/13/05402-0135 © 2013 Springer Science+Business Media New York
”Magnezit” Group, Moscow, Russia.
”Magnezit” Group, Satka, Chelyabinsk Oblast, Russia.