Effects of the oxides of chromium and vanadium on the desulfurizing capacities of slags
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Effects of the Oxides of Chromium and Vanadium on the Desulfurizing Capacities of Slags T. P. F L O R I D I S T h e i n c r e a s e d u s e of a l l o y s t e e l s h a s r e s u l t e d in an i n c r e a s e d p e r c e n t a g e of a l l o y - s t e e l s c r a p in t h e c h a r g e of s t e e l m a k i n g f u r n a c e s . C h r o m i u m , and to a l e s s e r e x t e n t v a n a d i u m , a r e p r e s e n t in m a n y a l l o y - s t e e l s . " D u r i n g t h e m e l t i n g of the s c r a p m o s t of t h e c o n t a i n e d c h r o m i u m and v a n a d i u m a r e o x i d i z e d and t h e o x i d e s f o r m e d d i s s o l v e in the s l a g . T h e p r e s e n c e of the o x i d e s of c h r o m i u m and v a n a d i u m a f f e c t s t h e p r o p e r t i e s of t h e s i n g . It w a s t h e r e f o r e c o n s i d e r e d d e s i r a b l e to d e t e r m i n e t h e e f f e c t s of the o x i d e s of c h r o m i u m and v a n a d i u m on t h e d e s u l f u r i z i n g c a p a c i t i e s of s y n t h e t i c s t e e l m a k i n g s l a g s . T h e d e s u l f u r i z i n g c a p a c i t i e s of s l a g s c a n b e e v a l u a t e d by t h e i r s u l f i d e and s u l f a t e c a p a c i t i e s , a s t h e y w e r e d e f i n e d by R i c h a r d s o n and F i n c h a m . ~ T h e s u l f i d e c a p a c i t y C S i s g i v e n by E q . [1], T. P. FLORIDIS is Professor of Metallurgical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Manuscript submitted November 14, 1977. METALLURGICAL TRANSACTIONS B
and it i s r e l a t e d to the e q u i l i b r i u m c o n s t a n t of r e a c t i o n tion [1'] a c c o r d i n g to E q . [1"], w h e r e a s t h e s u l f a t e c a p a c i t y i s g i v e n by E q . [2], and it i s r e l a t e d to t h e e q u i l i b r i u m c o n s t a n t of r e a c t i o n [2'] a c c o r d i n g to E q . [2"]: (pct S)(Po~ )1/2
Cs =
(psi).
a
[1]
1/2 S2(g)+ (O=)inslag = (s=)tnslag + 1/2 O2(g) [I']
a~ CS = K e q " YSO~ (pct S) , n xl/2 CSO4 = = (Pch)3/2. ~-S2
[1"1 [2]
1/2 S2(g) + (O=)}n slag + 3/2 O2(g) = (SO~)in slag [2']
~~
CSO~ = Keq " YSO~
[2,,]
w h e r e (pct S) is t h e w t p c t of s u l f u r in a s l a g at e q u i l i b r i u m w i t h an a t m o s p h e r e c o n t a i n i n g S2 and 02 a t known partial pressures. T h e p a r t i a l p r e s s u r e s of S2 and 02 in E q s . [1] and [2] a r e e x p r e s s e d in a t m . (1 a t m = 1.01325 • 105N/m2). It h a s b e e n d e t e r m i n e d 1'2 t h a t at o x y g e n p r e s s u r e s l e s s than 10 -5 to 10 -8 a t m , r e a c t i o n [1'] is p r e d o m i n a n t , w h e r e a s E q . [2'] p r e d o m i n a t e s at o x y g e n p r e s s u r e s g r e a t e r t h a n 10 -3 to 10 -4 a t m . Experimental Procedure. The experimental procedu r e w a s to e q u i l i b r a t e s y n t h e t i c s l a g s w i t h a t m o s p h e r e s h a v i n g k n o w n c h e m i c a l p o t e n t i a l s of s u l f u r and o x y g e n . It w a s s i m i l a r to t h e p r o c e
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