Kinetics of evolution of SO 2 from hot metallurgical slags
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D. P E L T O N , J. B R U C E
SEE, A N D J O H N F. E L L I O T T
The k i n e t i c s of the evolution of SOs g a s f r o m a liquid s y n t h e t i c b l a s t f u r n a c e - t y p e s l a g (CaO-A12Os-SiOs) in an a t m o s p h e r e of O2 + A r gas at a t o t a l p r e s s u r e of 1 a i m f o r 0.003 -< PO2 < 1.00 a i m has b e e n s t u d i e d in the r a n g e 1360 to 1460~ The p r o c e s s h a s b e e n followed by c o l l e c t i n g and a n a l y z i n g the SOs a s it f o r m s , and a l s o b y o b s e r v i n g the change in weight of the s l a g s a m p l e with t i m e . The effect of s l a g c o m p o s i t i o n h a s a l s o b e e n s t u d ied. F o r p a r t i a l p r e s s u r e s of oxygen l e s s than about 0.1 a i m , the r a t e i s v e r y r a p i d and is c o n t r o l l e d b y t r a n s p o r t in the g a s p h a s e . At g r e a t e r v a l u e s of PO2, the r a t e is much s l o w e r and is c o n t r o l l e d b y a c h e m i c a l p r o c e s s . In the high PO2 r e g i o n , the p r o c e s s is h a l f - o r d e r with r e s p e c t to the c o n c e n t r a t i o n of s u l f u r in the s l a g . T h i s h a l f - o r d e r d e p e n dence on s u l f u r c o n c e n t r a t i o n in the s l a g m a y b e e x p l a i n e d b y an i n i t i a l f a s t i r r e v e r s i b l e r e a c t i o n to f o r m two i n t e r m e d i a t e s p e c i e s which then d e c o m p o s e a t equal r a t e s to give the final p r o d u c t s . A d d i t i o n s to the s l a g of i r o n o r m a n g a n e s e o x i d e s g r e a t l y a c c e l e r a t e the r a t e of evolution of SO2 a t Poz = 1.00 a i m . T h i s is i n t e r p r e t e d to m e a n t h a t a c h a r g e t r a n s f e r p r o c e s s , p o s s i b l y involving S2- and O z- ions, is r a t e - c o n t r o l l i n g at PO2 = 1 a i m . It is a l s o a p p a r e n t that F e s* and F e 3ยง (or Mn ~ and Mn 3~) ions can a c t a s c h a r g e c a r r i e r s . Some m e a s u r e m e n t s with a c t u a l i n d u s t r i a l b l a s t f u r n a c e s l a g s a r e a l s o r e p o r t e d .
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g r o w i n g c o n c e r n f o r the e n v i r o n m e n t n e c e s s i t a t e s i n v e s t i g a t i o n of m e a n s to m i n i m i z e the c o n t a m i n a t i o n of the a t m o s p h e r e b y s u l f u r - b e a r i n g g a s e s . In a s t e e l plant, g a s e s containing s u l f u r m a y b e e v o l v e d when hot b l a s t f u r n a c e s l a g s , which m a y contain in e x c e s s of 2 wt p c t s u l f u r , and w a s t e p r o d u c t s of e x t e r n a l d e s u l f u r i z a t i o n p r o c e s s e s a r e e x p o s e d to a i r o r w a t e r v a p o r . The p r e s ent p a p e r r e p o r t s the r e s u l t s of a s t u d y of the r a t e at which s u l f u r d i o x i d e is r e l e a s e d b y a s y n t h e t i c liquid b l a s t f u r n a c e s l a g when it is e x p o s e d to an a t m o s p h e r e of oxygen and a r g o n at 1 a i m t o t a l p r e s s u r e . The t e m p e r a t u r e and c o m p o s i t i o n of t
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