Oxidation of molten ferrous sulphide
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the c o n v e n t i o n a l p y r o m e t a l l u r g i c a l c o p p e r s m e l t ing o p e r a t i o n , f e r r o u s s u l f i d e p r e s e n t in the c o p p e r m a t t e is p r e f e r e n t i a l l y o x i d i z e d on b l o w i n g a i r into the m a t t e p h a s e . The o x i d i z e d i r o n is s l a g g e d with s i l i c a and t h e a s s o c i a t e d s u l f u r is r e m o v e d a s s u l f u r d i o x i d e g a s . Although the t h e r m o d y n a m i c s of this p r o c e s s have b e e n s t u d i e d b y m a n y w o r k e r s , 1-s t h e r e h a v e b e e n v e r y few s t u d i e s on the k i n e t i c a s p e c t of t h i s p r o c e s s . An i n v e s t i g a t i o n of the k i n e t i c s m i g h t b e c o n s i d e r e d a s i m p o r t a n t not o n l y f o r b e t t e r u n d e r s t a n d i n g of the c o n v e n t i o n a l c o p p e r s m e l t i n g o p e r a t i o n b u t a l s o f o r d e v e l o p i n g new p r o c e s s e s such a s the c o n tinuous c o p p e r s m e l t i n g p r o c e s s . We have r e c e n t l y r e p o r t e d on the o x i d a t i o n r a t e s of m o l t e n c o p p e r and c o p p e r s u l f i d e . 6 As a continuation of the k i n e t i c s t u d y of c o p p e r s m e l t i n g , the o x i d a t i o n of m o l t e n f e r r o u s sulfide was s t u d i e d in t h i s work, p r i o r to o x i d a t i o n of c o p p e r m a t t e s . In t h i s study, the o x i d a t i o n of f e r r o u s s u l f i d e was c a r r i e d out u n d e r the c o n d i t i o n w h e r e the o v e r a l l r e a c t i o n r a t e was c o n t r o l l e d b y g a s d i f f u s i o n and the k i n e t i c a s p e c t of the p r o g r e s s of t h i s r e a c t i o n was i n v e s t i g a t e d . EXPERIMENTAL
of diffusing g a s i n s i d e the s a m p l e tube. The tube was then p l a c e d into a q u a r t z tube with a h a n g e r . A s i l i c o n c a r b i d e f u r n a c e having an u n i f o r m t e m p e r a t u r e zone of a p p r o x i m a t e l y 10 c m was u s e d . The f u r n a c e t e m p e r a t u r e was c o n t r o l l e d to •176 a t the o p e r a t i n g t e m p e r a t u r e s of 1200 and 1230~ The s a m p l e tube was l o c a t e d s l i g h t l y b e l o w the hot zone of the f u r n a c e so that the t e m p e r a t u r e a t the open end of the tube was s l i g h t l y h i g h e r than the b o t t o m . T h i s p r e v e n t e d t h e r m a l c o n v e c t i o n of g a s i n s i d e the s a m p l e tube. A P t - P t - 1 3 pot Rh t h e r m o c o u p l e was i n s e r t e d f r o m the b o t t o m of t h e f u r n a c e and the t e m p e r a t u r e j u s t b e l o w the b o t t o m of the s a m p l e tube was m e a s u r e d . Oxygen and a r g o n g a s w e r e d r i e d and s e p a r a t e l y m e a s u r e d b y m e a n s of c a l i b r a t e d d i f f e r e n t i a l p r e s s u r e t y p e flow m e t e r s . The g a s e s w e r e then m i x e d b e f o r e b e i n g a d m i t t e d into the b o t t o m of the f u r n a c e . The c o n t e n t of ox
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