Kinetics of the reactions between silica and alumino-silicate refractories and molten iron

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Schematic diagram of apparatus I)furnoce shell; 2) therrnocouple ; 3) carbon elements; 4) furnace tube; 5) drive shaft; 6)viewing port; 7) sealing cap; 8)graphite specimen holder; 9)specimen; IO)reoction crucible and melt; fl)pyrometer; 12)insulating refractory J3)roiler bearing 14) sampling hole

Fig. l--Diagram of apparatus. on this p e d e s t a l and s e r v e d to contain the m o l t e n i r o n . Reaction a t m o s p h e r e s were c o n t r o l l e d b y i n t r o d u c i n g and e x h a u s t i n g g a s e s through two tubes set in a w a t e r cooled b r a s s cap on top of the f u r n a c e tube. A q u a r t z window set in this cap allowed continuous o b s e r v a t i o n of the m e l t and a ~ in. stoppered hole was used to take s a m p l e s f r o m the m e l t . A s e a l e d d r i v e shaft (15 in. long) was made f r o m ~ in. d r i l l rod and a graphite s p e c i m e n holder was s c r e w e d onto this d r i v e shaft. The shaft was p a s s e d through r o l l e r b e a r i n g s in the cap with two " 0 " r i n g s m a i n t a i n i n g a g a s - t i g h t seal about the shaft. Additional guidance for the shaft was provided b y a n o t h e r set of r o l l e r b e a r i n g s p o s i t i o n e d d i r e c t l y above the cap. A h o l l o w - s p i n d l e , v a r i a b l e speed s t i r r e r was attached to the shaft. The shaft could be r a i s e d or l o w e r e d d u r i n g an e x p e r i m e n t .

MATERIALS The r e f r a c t o r y s p e c i m e n s used were c y l i n d r i c a l r o d s , 89in. diam and 4 in. in length. The t r a n s l u c e n t fused s i l i c a r o d s * (99.93 pet silica) and s i l o - c a s t *GeneralElectricCo. " S h e l r o c k " s i l i c a rods* ( 9 9 . ' / p c t s i l i c a ) r e q u i r e d *GlasrockProductsInc. VOLUME 5, JANUARY 1974-249

Table I. Properties of Refractory Materials

Type of Refractory

SiO2

AI~O3

"Shelrock" silica High silica brick Fire-clay brick

99.0 95.7 53.2

0,2 0.7 42,8

Chemical Composotion (Pet) Fe20~ CaO MgO 0.8 1.07

2.7 0.47

0.2 0.57

TiO2

Alkalis

Bu~k Density (g/cm3)

Apparent Porosity (Pet)

0.1 1.11

0,2 0.87

1.92 1.75-1.82 2.36

12-18 20-23 7.3

Table II. Properties of Metals Used

Armco Iron Electrolytic "Derby" Iron

C

Mn

P

S

Si

Cu

0.015 0,005

0.018 0.0028

0.005 0.001

0.018 0.003

0.005 0.004

0.052 0.0054

m i n o r m a c h i n i n g w h e r e a s the high s i l i c a * and the f i r e *GeneralRefractories Ltd. clay b r i c k *

s p e c i m e n s w e r e c o r e - d r i l l e d f r o m the

*Kaiser Refractories Ltd.

b r i c k s . A s u m m a r y of the p r o p e r t i e s of t h e s e m a t e r i a l s is given in T a b l e I. In addition, two t y p e s of p u r e alumina were investigated, namely recrystallized alumina* and s i n g l e c r y s t a l s a p p h i r e r o d s . * * *McDanel Refractory Co. **Linde Ltd.

A r m c o i r o n and e l e c t r o l y t i c i r o n w e r e used a s c h a r g e m a t e r i a l s and w e r e o b t a i n e d c o m m e r c i a l l y . A n a l y s e s of t h e s e m a t e r i a