Kinetics of sulfation of atlantic ocean manganese nodules
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HECKE
AND
R. W. BARTLETT
The sulfation k i n e t i c s of m a n g a n e s e nodules f r o m the B l a k e P l a t e a u of the A t l a n t i c O c e a n w e r e d e t e r m i n e d u s i n g a TGA m e t h o d in low c o n c e n t r a t i o n s of SO2, t y p i c a l of p o w e r plant s t a c k g a s e s . Above 400~ the r a t e i s p r o p o r t i o n a l to the 802 p r e s s u r e and the u n r e a e t e d s o l i d f r a c t i o n . The r a t e i s i n d e p e n d e n t of nodule p a r t i c l e s i z e and the a p p a r e n t a c t i v a t i o n e n e r g y i s low. The s o r p t i o n c a p a c i t y i s c o m p l e t e s u l f a t i o n of the m a j o r c o n s t i t u e n t o x i d e s ; Mn, F e , and Ca. L e a c h i n g c o m p l e t e l y s u l f a t e d n o d u l e s in b o i l i n g w a t e r p r o v i d e s N i , Cu, and Co e x t r a c t i o n s above 80 pet. Much of the m a n g a n e s e but l i t t l e of the i r o n i s a l s o e x t r a c t e d . At 300~ the SO2 s o r p t i o n c a p a c i t y i s l o w e r with m o s t of the s u l f a t i o n a t t r i b u t e d to the manganese oxides.
BOTHd r y
and wet ( s l u r r y ) m a n g a n e s e o x i d e s have b e e n
s h o w n to be e f f e c t i v e s o r b e n t s for SO2.1-z M a n g a n e s e
o x i d e s can be r e g e n e r a t e d f r o m MnSO4 by t h e r m a l d e c o m p o s i t i o n , 2 by r e d u c t i o n and by wet c h e m i c a l m e t h o d s . T h e B u r e a u of M i n e s p r o c e s s i n v o l v e s NaOH which p r o d u c e s Na2SO4 that i s s u b s e q u e n t l y e l e c t r o l y z e d . 1 T h e D A P - M n p r o c e s s h a s b e e n d e v e l o p e d by M i t s u b i s h i H e a v y I n d u s t r i e s 4 in J a p a n and i n s t a l l e d on a s e m i c o m m e r c i a l b a s i s at the Y o k k a i c h i p o w e r s t a t i o n . T h i s p r o c e s s i n v o l v e s d r y s o r p t i o n followed by a m m o n i a s c r u b b i n g in an a i r - b l o w n t o w e r to r e g e n e r a t e the m a n g a n e s e oxide and p r o d u c e s a l a b l e a m m o n i u m s u l f a t e . The u s e of m a n g a n e s e s e a n o d u l e s f o r s o r p t i o n of SO2 f r o m s t a c k g a s e s was f i r s t p r o p o s e d by Z i m m e r l e y . s T h e o c e a n f l o o r s c a r r y huge r e s e r v e s of t h e s e nodules 6 and both, a t h r o w - a w a y p r o c e s s and c y c l i c r e g e n e r a t i o n s o r p t i o n can be c o n s i d e r e d . A f i n a l e c o n o m i c e v a l u a t i o n d e p e n d s on d e v e l o p m e n t of m i n i n g m e t h o d s and c o s t s . M a n g a n e s e s e a nodules a r e a c o m p l e x m i x t u r e of s e v e r a l m e t a l o x i d e s , i n c l u d i n g the o x i d e s of m a n g a n e s e and i r o n and s o m e t i m e s c a l c i u m c a r b o n a t e . M i n o r , but o c c a s i o n a l l y e c o n o m i c a l l y i n t e r e s t i n g , a m o u n t s of Cu, Ni, and Co o x i d e s a r e u s u a l l y p r e s e n t . At l e a s t t h r e e m a n g a n e s e oxide m i n e
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