Experimental observations of chemical and thermal gradients in an experimental BOF
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DESPITEthe w i d e s p r e a d use
of the b a s i c oxygen f u r n a c e , the m e c h a n i s m s of the r e a c t i o n s taking place a r e not well u n d e r s t o o d . F o r e x a m p l e , t h e r e is s t i l l c o n s i d e r a b l e d i s c u s s i o n c o n c e r n i n g p r o b l e m s such as the c i r c u l a t i o n p a t t e r n within the bath, the effect of depth of p e n e t r a t i o n of the jet upon the extent of depho s p h o r i z a t i o n and the c h e m i c a l changes leading to the s o - c a l l e d slopping condition d u r i n g c o n v e r t e r o p e r a tion. The objective of this r e s e a r c h was to p r o v i d e a b a c k g r o u n d for a n a l y z i n g these and other o p e r a t i n g p r o b l e m s by o b s e r v i n g changes in the c h e m i c a l and t h e r m a l g r a d i e n t s in the bath as the o p e r a t i n g p a r a m e t e r s , such as lance height and d r i v i n g p r e s s u r e , were varied. REVIEW OF T~-IE L I T E R A T U R E T h e r e a r e no p u b l i s h e d data c o n c e r n i n g the c h e m i cal g r a d i e n t s in the BOF bath. Some a t t e m p t s at m e a s u r e m e n t of the bath t e m p e r a t u r e d u r i n g o p e r a t i o n s have been m a d e , but t h e r m o c o u p l e p r o t e c t i o n p r o b l e m s have b e e n s e v e r e . Refs. 1 to 19 i n d i c a t e that in c o m m o n A m e r i c a n p r a c t i c e the jet p e n e t r a t e s deeply, i.e. beyond the c e n t e r of the bath. On the other hand, r e f e r e n c e s 20 to 27 teach that shallow jet p e n e t r a t i o n is e s s e n t i a l for good d e p h o s p h o r i z a t i o n . The r e s u l t s of l a b o r a t o r y i n v e s t i g a t i o n s also appear to be c o n t r a d i c t o r y . It is suggested on one hand that d e c a r b u r i z a t i o n is a c c o m p l i s h e d through a s u b s t a n t i a l FRANKLIN E. ROTE is Senior Research Engineer, U. S. Steel Corp. RICHARD A. FL1NN is Professor of MetallurgicalEngineering, University of Michigan. Manuscript submitted November 18, 1968. METALLURGICAL TRANSACTIONS
c a r b o n boil 28 while, in c o n t r a s t , o t h e r s indicate that the m e c h a n i s m is d i r e c t j e t - t o - b a t h i n t e r a c t i o n at or n e a r the j e t i m p i n g e m e n t a r e a . 29 The m e c h a n i c s of bath s t i r r i n g a r e also c o n t r o v e r s i a l . Ref. 30 d e s c r i b e s g e n e r a l t u r b u l e n c e , 31 p o s t u l a t e s a down in the c e n t e r c i r c u l a t i o n while 11 gives data showing a motion that is up in the c e n t e r and r a dially outward at the s u r f a c e . F i n a l l y , although the end r e s u l t s of d i f f e r e n t o p e r ating conditions a r e d e s c r i b e d , the m e c h a n i s m w h e r e by these end r e s u l t s a r e achieved a r e not well known. If the m e c h a n i s m s can be d e t e r m i n e d , i m p r o v e m e n t in o p e r a t i n g p r a c t i c e should be p o s s i b l e . PROCEDURE The novel and m o s t i m p o r t a n t p a
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