Mathematical description of the thermodynamic properties of the systems Fe-0 and Fe-O-SiO 2
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The t h e r m o d y n a m i c p r o p e r t i e s of the liquid slag and i r o n p h a s e s in the s y s t e m F e - O - S i O 2 and the s o l i d and liquid p h a s e s in the s y s t e m F e - O have been c o r r e l a t e d by m a t h e m a t i c a l r e l a t i o n s that d e s c r i b e the s o l u t i o n p h a s e s in t e r m s of h y p o t h e t i c a l s o l u t i o n s p e c i e s in e q u i l i b r i u m with e a c h other, and b e h a v i n g in a n o n i d e a l m a n n e r , d e s c r i b e d by a f o r m of the M a r g u l e s e q u a t i o n s . P a r a m e t e r s t h a t d e s c r i b e the p r o p e r t i e s of the s p e c i e s , and t h e i r nonideal behavior, are determined empirically from existing thermochemical measurem e n t s . The c o r r e l a t i o n s a r e , for the m o s t p a r t , a s a c c u r a t e a s the d a t a on which they a r e b a s e d . T h e m e t h o d s u p p l i e s a much n e e d e d p r a c t i c a l d e s c r i p t i o n of s l a g c h e m i s t r y that can be e x t e n d e d to c o m p l e x s l a g s of four o r m o r e c o m p o n e n t s .
A v o l u m i n o u s l i t e r a t u r e e x i s t s on the t h e r m o d y n a m i c p r o p e r t i e s of i r o n - s i l i c a t e s l a g s , at t e m p e r a t u r e s and c o m p o s i t i o n s s c a t t e r e d t h r o u g h o u t the r a n g e s of p r a c t i c a l i n t e r e s t . Some of the d a t a a p p e a r to be i n t e r n a l l y c o n s i s t e n t and r e l i a b l e ; o t h e r d a t a s e t s show s i g n i f i c a n t d i s a g r e e m e n t among t h e m s e l v e s , and choice of the m o s t r e l i a b l e v a l u e s p r e s e n t s d i f f i c u l t i e s to the p r o c e s s e n g i n e e r . In g e n e r a l , the f r a g m e n t a r y n a t u r e of the e x p e r i m e n t a l s t u d i e s , the e x i s t e n c e of many r e g i o n s of t e m p e r a t u r e and c o m p o s i t i o n w h e r e d a t a a r e lacking, and the l a c k of a m a t h e m a t i c a l d e s c r i p t i o n of the v a r i a t i o n of t h e r m o d y n a m i c p r o p e r t i e s with t e m p e r a t u r e and c o m p o s i t i o n , a l l c o n t r i b u t e to u n d e r u t i l i z a t i o n of t h i s v e r y v a l u a b l e i n f o r m a t i o n in p r o c e s s d e s i g n , c o n t r o l and p r o c e s s m o d e l l i n g . In r e c e n t y e a r s we have b e e n e n g a g e d at C o l u m b i a in an e f f o r t to fill the n e e d f o r a p r a c t i c a l and a c c u r a t e m a t h e m a t i c a l d e s c r i p t i o n of the t h e r m o d y n a m i c p r o p e r t i e s of s l a g s , m a t t e s and m o l t e n a l l o y s for use in p r o c e s s c a l c u l a t i o n s . An e a r l i e r p a p e r by one of us ~ g i v e s a m a t h e m a t i c a l d e s c r i p t i o n of the m o l t e n m a t t e s y s t e m C u - N i - S ; the p r e s e n t p a p e r r e p o r t s our c o r r e lation f o r the s y s t e m F e - O - S i O 2 and i t s s u b s y s t e m F e - O ; we intend to r e p o r t so
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