Fluidized-bed chlorination rates of australian rutile
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AND
R. F. JENSEN
Rates of c h l o r i n a t i o n of A u s t r a l i a n r u t i l e o r e u s i n g 1) c a r b o n m o n o x i d e and 2) coke as r e d u c i n g agents have b e e n i n v e s t i g a t e d in a 4.75 cm d i a m fluidized bed r e a c t o r at temperatures in the r a n g e 1143 K to 1311 K. E m p i r i c a l equations a r e p r o p o s e d for the r a t e s of r e action of the o r e in both the CO-C12 and C-CI~ s y s t e m s .
I N the m a n u f a c t u r e of TiO 2 p i g m e n t by the c h l o r i d e p r o c e s s , TiC14 is p r o d u c e d as an i n t e r m e d i a t e by the high t e m p e r a t u r e f l u i d i z e d - b e d c h l o r i n a t i o n of TiO2 o r e s in the p r e s e n c e of c a r b o n . As p a r t of a p r o g r a m to o p t i m i z e plant c h l o r i n a t o r o p e r a t i o n , a l a b o r a t o r y study of the r a t e s of A u s t r a l i a n f u t i l e c h l o r i n a t i o n was u n d e r t a k e n for both c a r b o n monoxide and coke as r e d u c i n g a g e n t s . This p a p e r p r o p o s e s a r e a c t i o n r a t e model, d e r i v e s e m p i r i c a l equations for the r u t i l e c h l o r i n a t i o n r a t e s and a p p l i e s the r e s u l t s to m a x i m i z i n g c h l o r i n e u t i l i z a t i o n r a t e in commercial fluidized-bed chlorinators. The o v e r a l l r e a c t i o n for the CO-C12 s y s t e m m a y be r e p r e s e n t e d by WiO2 (s) + 2CO(g) + 2C1~ (g) ~- WiCl4 (g) + 2CO~ (g) [A] while, for the C-C12 s y s t e m , the r e a c t i o n s a r e
TiO2(s)+2Cle(g)+C(s)~ TIC14 (g) TiO2 (s) + 2C12 (g) + 2C (s) ~
+ CO2 (g)
TIC14 (g) + 2CO(g)
CO~(g) + C ( s ) ~- 2CO(g).
[B] [C] [D]
R e l e v a n t c h l o r i n a t i o n r a t e data for TiO, o r e s a r e not r e a d i l y a v a i l a b l e in the l i t e r a t u r e . Dunn I c h l o r i n a t e d A u s t r a l i a n r u t i l e and b e n e f i c i a t e d i l m e n i t e in fluidized and packed beds u s i n g CO-C1 z and COCl 2. F o r the CO-C12 s y s t e m , the r e a c t i o n r a t e was p r o p o r t i o n a l to both o r e weight and the p a r t i a l p r e s s u r e s of CO and CI,. The a c t i v a t i o n e n e r g y is given as 20.9 k c a l / m o l (87.5 k J / m o l ) . Bergholm" c h l o r i n a t e d A u s t r a l i a n r u t i l e in the p r e s ence of CO and c a r b o n . F o r the CO-C12 c h l o r i n a t i o n , an a c t i v a t i o n e n e r g y of a p p r o x i m a t e l y 25 k c a l / m o l (104.7 k J / m o l ) was obtained. In c o n t r a s t to D u n n ' s findings, the r a t e of r e a c t i o n was p r o p o r t i o n a l to CO c o n c e n t r a t i o n , but i n d e p e n d e n t of C12 c o n c e n t r a t i o n . B e r g h o l m s u g g e s t s that this i n d i c a t e s a r a t e - c o n t r o l l i n g r e d u c t i o n step, followed by r a p i d c h l o r i n a t i o n of the r e d u c e d r u t i l e . F o r the C-C12 s y s t e m , the c h l o r i n a t i o n r a t e was much higher than with CO as r e d u c i n g agent. Also, the r e a c t i o n r a
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