EFFECT OF WOLLASTONITE MINERAL (CaO SiO2

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Key Engineering Materials Vol. 352 (2007) pp. 107-110
online at http://www.scientific.net
© (2007) Trans Tech Publications, Switzerland
Online available since 2007/08/14
Effect of Wolastonite Mineral (CaO SiO2) Content in Continuous Casting
Powder to SEN Erosion
S. Dević 1,a and R.Carli 2,b
1
IMS Institute of materials, Bulevar vojvode Mišića 43, 11000 Beograd, Srbija i Crna Gora,
2
a
Prosimet SpA, Via Rodi 10, 24040 Filago (BG) Italy
Email: [email protected] , b Email: [email protected]
Keywords: mineral wollastonite, erosion, casting powder, mixture, micro view, submerge entry
nozzle - SEN
Abstract. The basic idea of the work was to analyze the effect of the wollastonite mineral CaO
SiO2 content in the continuous casting powder related to the SEN erosion. In order to realize the
research, experiments were conducted in the laboratory conditions. The research, experiment, was
realized in the Magnohrom Kraljevo laboratory, and cryptonym furnace EV16 was used for
refractory material behavior. Cut SEN pieces from the slag zone in the reduction atmosphere were
treated in the furnace with three types of casting powder of different mixtures ratio of SRD1
(without wollastonite) and SRD2 (with wollastonite): Casting powder 1 - SRD1/SRD2 = 50/50 %,
Casting powder 2 - SRD1/SRD2 = 25/75 % and Casting powder 3 - SRD1/SRD2 = 75/25 %.
Temperature of the experiment was in the range of 15200C – 15400C, and treatment time was
changed simulating the average casting time of the heat; one heat (45 min), two heats (90 min), and
three heats (135 min). The experiment pointed out that the erosion of the SEN was reduced with the
increased ratio of wollastonite in the casting powder. The erosion rate of the SEN exposed to the
casting powder 2 in the laboratory conditions was 0.0055 mm/min, whilst the erosion rate of the
SEN exposed to the casting powder 3 (with the least wollastonite content) was 0.0075 mm/min.
Erosion rate of SEN exposed to the casting powder 2 was lower for the 26.27 % related to the
casting powder 3, and 17.90% lower than the erosion rate of the casting powder 1 (the erosion rate
of the casting powder 1 was 0.0067 mm/min). These laboratory experiments are very consistent
with results obtained in the plant conditions [1,2,3]. At that time, results indicated that SRD1
casting powder without wollastonite has the erosion rate 46 % higher than SRD2 casting powder
with wollastonite. On the basis of the laboratory researches and earlier plant conditions researches it
could be concluded that wollastonite mineral content in the casting powders has significant effect
on the SEN erosion, in the way that the SEN erosion rate was decreased with the increased
wollastonite content in the casting powders.
Introduction
To confirm results in plant conditions, which have proved the influence of casting powder with
contents of wollastonite on reduction of external erosion SEN, it was necessary to prove it also in
laboratory conditions. Obtained results have confirmed influence of casting powder with contents of
wollastonite on reduction of external erosion SEN and direct contribution on reduction of erosion
SEN.
Testing results and discussion
SRD1 casting powder without wollastonite and SRD2 casting powder with wollastonite mixed in
different relation, and so obtaining casting powders used in experiment. Table 1 and Table 2 show
chemical and mineralogical composition of casting powders. Fig. 1 micro view casting powders
confirms that casting powder 2 possesses the biggest contents of wollastonite. Wollastonite appears
in prismatic, crystal sections. Fig. 2 shows appearance of prepared SEN samples, and Fig. 3 shows
appearance of samples after treatment in laboratory conditions.
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Innovation in Ceramic Science and Engineering
Table 1 Chemical compositions of casting powders, wt-%
Type of
Na2O
Casting powders
CaO SiO2 Al2O3 MgO MnO Fe2O3
+K2O
Casting powder 1
Casting powder 2
Casting powder 3
C
F
LOI
32.11 34.36
7.11
0.82
0.03
0.81
5.72
7.80
4.51
14.47
32.11 34.00
6.36
0.87
0.03
0.83
7.03
8.06
4.43
14.34
32.34 34.22
6.28
0.73
0.02
0.77
6.66
7.41
4.80
14.39
Table 2 Mineralogical composition of casting powders
Casting
powder 1
Calcite
Quartz
Graphite
Wollastonite
Fluorite
Hematite
Casting
powder 2
Wollastonite
Graphite
Quartz
Calcite
Fluorite
Hematite
Casting
powder 3
Calcite
Quartz
Fluorite
Graphite
Wollastonite
Hematite
Fig. 1 Micro view of casting powders 1, 2 and 3
(Refracted light – immersion with xilol, magnification x200)
Fig. 2 Macro view samples SEN prepared for laboratory experiment
45 min
90 min
135 min
Fig. 3 Macro view samples of SEN after treatment in cryptonym furnace with casting powder 1, 2,
3 on constant temperature T=15400C, and different time 45 min, 90 min and 135 min.
Table 3 shows parameters in experiment and values of measured external erosion of SEN samples.
The biggest external erosion is provoked by action of casting powder 3 which has the smallest
contents of wollastonite in mineral structure. External erosion of SEN samples is biggest because of
action of casting powder 3.
Key Engineering Materials Vol. 352
109
Table 3 Results external erosion samples of SEN after experiments in the laboratory conditions
De
(mm)
De-Dp
(mm)
Depth
erosion
(mm)
Erosion
(mm/min)
De
(mm)
De-Dp
(mm)
Depth
erosion
mm)
Erosion
(mm/min)
Erosion
(mm/min)
1
5.9
0.9
0.45
0.01
6.1
1.10
0.55
0.006
6.15
1.15
0.575
0.0042
2
5.82
0.82
0.41
0.0091
5.8
0.80
0.40
0.0044
5.87
0.87
0.435
0.0032
3
5.97
0.97
0.485
0.0107
6.2
1.17
0.585
0.0065
6.4
1.4
0.70
0.0052
Type of
Casting
powder
Depth
erosion
(mm)
Temperature in experiment
T= 15400C
Time of experiment
V = 135 min
Parameters external erosion
SEN (particles)
De-Dp
(mm)
T= 15400C
Time of experiment
V = 90 min
SEN (particles)
De
(mm)
T= 15400C
Time of experiment
V = 45 min
SEN (particles)
Casting powder 1 (External erosion average 0.0067mm/min); Casting powder 2 (External erosion
average 0.0055mm/min); Casting powder 3 (External erosion average 0.0075mm/min).
Fig. 4 shows microstructures forming on samples of SEN after finished laboratory experiment.
Micro view samples Fig. 4 shows different microstructure SEN samples which is form during the
action of casting powder of different microstructure and different action length. Reviews 2a, 2b and
2c (Fig. 4) show the results of action of casting powder 2 through small erosions and changes of
SEN samples' microstructure which are almost identical as primary SEN microstructure. 2a – shows
smaller penetration of slag and rest of the primary SEN microstructure with good visible graphite
(fiber) strips and grains of corundum, 2b – similar review of microstructure's appearance as in 2a,
while 2c represents microstructures where directed graphite strips are appearing, and in the same
time they prevent further penetration of slag. The results of action of casting powder 3 which are
shown in 3a, 3b and 3c (Fig. 4) represent the biggest erosion and deep penetration slag in
microstructure, appearance of spinel and rather changed primary SEN microstructure with small
number of corundum grains and graphite (fiber) strips.
Conclusion
Experimental results (in laboratory conditions) have shown big influence of casting powders with
wollastonite and wollastonite itself on reduction of external erosion SEN. These results also
confirmed previous results from experiment, which was conducted in plant conditions [1] [2] [3].
Reference
[1] S.Devic, Mineralogical study of casting powders effect on nozzles during continuous steel
casting, D. Ph. Thesis, Faculty of mining and geology Belgrade, (2000),
[2] S.Devic, Mineralogical study on the nature and effect of different casting powders on
alumographite nozzles erosion, (2001), 7th European Conference on Advanced Materials end
Processes, Rimini – Italy, Proceeding - abstract, pp 301, Proceeding on CD – full paper
110
Innovation in Ceramic Science and Engineering
[3] S. Devic, I.Zivojinovic, R. Carli, G.Faraveli, SEN wearing – experimental evidences of strong
casting powder effect, (2002), 4th European Continuous Casting Conference, International
Convention Center, Birmingham, UK, Proceeding, pp 932 – 938
Cast. Powd. 1
Cast. Powd. 2
1a – 45 min
2a – 45 min
1b – 90 min
1c -135 min
2b – 90 min
2c – 135 min
Cast.Powd. 3 3a – 45 min
3b – 90 min
3c – 135 min
Fig. 4 Micro view samples of SEN ( Reflected light – magnification x250) after treatment in
Cryptonym furnace with casting powder 1, 2, 3 on constant temperature T=15400C, and different
time 45 min, 90 min and 135 min.

EFFECT OF WOLLASTONITE MINERAL (CaO SiO2

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