Measurement of melting temperatures of blast furnace slags by temperature gradient melting
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11b0
12b0
13b0 To.mperature~
14b0
1.~
Fig. l -D.T.A. traces for some blast furnace slag samples.
Table I. Composition of Slag Samples
Sample No.
A 1 2 0 3 CaO
SiO2
MgO
MnO
FeO TiOz
S
AI* A2 A4 A5 A6 A8 A9
25.5 23.2 19.6 25.4 30.3 28.4 26.8
29.0 35.5 45.4 42.1 39.3 43.1 46.5
35.5 32.3 27.3 25.4 23.7 22.2 20.9
4.5 4.1 3.5 3.2 3.0 2.8 2.6
3.8 3.5 2.9 2.7 2.5 2.4 2.2
1.0 0.9 0.8 0.7 0.7 0.6 0.6
0.2 0.2 0.2 0.1 0.1 0.1 0.1
0.5 0,5 0.4 0,4 0,3 0,3 0.3
B3 B4 B5 B6 B7 B8
37.9 42.7 37.0 44.4 38.5 45.0
24,2 22.3 32.7 28.8 34.7 31.1
29.6 27.3 23.7 20.9 20.9 18.7
3.8 3.5 3.6 2.6 2.6 2.4
3.2 2.9 2.5 2.2 2.2 2.0
0.8 0.8 0.7 0.6 0.6 0.5
0.2 0.2 0.1 0.1 0.1 2.1
0,4 0,4 0,3 0,3 0,3 0,3
*Masterslagfrom Rourketa SteelPlant, Rourkela,Orissa, India.
(approx. 7.0 • 1.5 • 1.0 cm ) containing f i n e l y g r o u n d slag s a m p l e s w e r e p l a c e d i n s i d e the f u r n a c e f o r t h i r t y m i n u t e s . On r e m o v a l f r o m the f u r n a c e the b o a t s , w hi c h co n t ai n ed only a few g r a m s of s a m p l e , c o o l e d in a i r q u i c k l y . T h e r e w as i n s i g n i f i c a n t r e a c t i o n of the b o a t itself during exposure. Th e t e m p e r a t u r e at any g i v e n r e g i o n of the s a m p l e was obtained f r o m the l o c a t i o n of the r e g i o n and the t e m p e r a t u r e p r o f i l e . T h e o v e r a l l u n c e r t a i n t y of locating the point of t r a n s i t i o n and d e t e r m i n i n g the c o r r e s p o n d i n g t e m p e r a t u r e was g e n e r a l l y about •176 M o s t s a m p l e s showed t h r e e c l e a r n a r r o w z o n e s of m a r k e d p h y s i c a l cha~ge m a r k e d by points A, B, and C in F i g . 2. T h e s e m ay be c h a r a c t e r i z e d a s f o l l o w s :
ISSN 0360-2141/79/1211-0677500.75/0 9 1979 AMERICAN SOCIETY FOR METALSAND THE METALLURGICALSOCIETY OF A1ME
V O L U M E10B, DECEMBER 1979 677
Fig. 2-Temperature profile of furnace, position of refractory boats and location of transformation regions.
A) A region where fusion became clearly visible. 13) A r e g i o n w h e r e f u s i o n a p p e a r e d a l m o s t c o m p l e t e . C) A r e g i o n w h e r e t h e r e b e g a n a n a l m o s t c o m p l e t e l y clear glassy phase. It w a s n o t p o s s i b l e t o d e t e r m i n e t h e t e m p e r a t u r e a t which the first liquid phase appeared. However the point where fusion seemed complete was clearly i n d i c a t e d . T h e d i s a p p e a r a n c e of t h e l a s t t r a c e s of s o l i d s a n d c r e a t i o n of f u l l y c l e a r g l a s s y p h a s e w a s also well defined. It s h o u l d b e n o t e d t h a t t h e f i n d i n g s of t h e D T A a n d t h o s e of t h e t i m e g r a d i e n t m e l t i n g ( T G M ) t e c h n i q u e cannot be matched very critically. For example, the solidus temperature determined by DTA denotes the a p p e a r a n c e of t h e f i r s t l i q u i d p h a s e d u r i n g h e a t i n g . This may not be immediately visible in TGM. The liquid ph
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