CPT International 02/2017

above the inside bottom
All in
one line
M3: In the middle of the refractory
inside bottom
the inside bottom
Figure 1:
ously held at that temperature. This is
to be performed with maximum efficiency
and flexibility, while subjecting
the ladle to fewest possible temperature
changes, in order to maximize the lining
life and minimize ladle repair.
980
900
Temperature measurement in the
Test set-up
Figure 1 shows the positions of the
thermocouples in the refractory lining
of the 4-t pouring ladle.
Inherent energy content of
a pouring ladle at operating
temperature
Through-heating of a ladle depends
largely on the heat content of the refractory
material, especially the superheating
of the inside surface zone. After
the molten metal has been filled
into the ladle, the thermal energy
from the melt is introduced into the
ladle and transferred towards the outside
via the refractory lining. Especially,
the reading at measuring point M 1,
at 2.5 cm from the inside refractory surface,
shows a pronounced temperature
rise (approx. 970 °C; Figure 2) after the
molten iron has been filled into the ladle.
For the here presented experiment,
the ladle was filled with 3 t of molten
iron, simulating optimal through-heating.
After 8 min, the melt was poured.
At that stage, the first 2.5 cm of the refractory
lining thickness were superheated
(Figure 3). Within this surface
layer of only 2.5 cm thickness, a temperature
difference of more than 550 °C
Temperature in °C
820
740
660
580
500
M3
M2
420
12:01:26 12:02:53 12:04:19 12:05:46 12:07:12 12:07:12 12:10:05 12:11:31 12:12:58
Figure 2: Heating of the refractory lining by the melt for approx. 8 min. Thermal be-
the iron melt in the ladle at 12 o’clock: 1,501 °C
between the surface and M 1 was measured.
In case of ladle preheating by
burners, it is recommended that care
should be taken to ensure that this heat
content be input by the burner. Otherwise
it would be extracted from melt.
Time in min
Resistance to temperature
changes
When ladles are being filled with molten
metal, the inside surface layer of the
ladles heats up. The temperature transfer
from the melt is lower when the temperature
of this layer is already at a high
level before the molten metal is filled in,
(figure 3). When this layer is “cold” or
has not been heated up to a sufficiently
high level, the temperature changes
will be great, leading to early wear,
short lifetimes and slag caking in the ladles.
After pouring, this energy content
is transferred into the interior of the refractory
lining via the superheated surface
zone, as shown in figure 3.
Casting Plant & Technology 2 / 2017 11