The rate of chlorination of metals and oxides: part III. the rate of chlorination of fe 2 O 3 and NiO in Cl 2 and HCL
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I N p r e v i o u s p u b l i c a t i o n s 1'2 s e v e r a l e x a m p l e s of m e t a l l u r g i c a l p r o c e s s e s were d i s c u s s e d in which v o l a t i l e m e t a l c h l o r i d e s play a m a j o r r o l e . F o r e x a m p l e : Hend e r s o n s has r e p o r t e d on the e x t r a c t i o n of t a n t a l u m , c o l u m b i u m , and t u n g s t e n by the f o r m a t i o n of v o l a t i l e c h l o r i d e s f r o m complex o r e s u s i n g c h l o r i n e , Okahara and Kwaski 4 have s e l e c t i v e l y c h l o r i n a t e d m a n g a n i f e r o u s i r o n o r e s with c h l o r i n e , and Reeve 5 has worked on the c h l o r i n a t i o n of i r o n o r e s with HC1. Recently, c o n s i d e r able work has been done on the s e g r e g a t i o n r o a s t i n g p r o c e s s e s for copper 6 and n i c k e l 7 r e c o v e r y f r o m l a t e r i t e o r e s . In these p r o c e s s e s HC1 is the c h l o r i n a t i n g agent. In p r e v i o u s work the a u t h o r s have r e p o r t e d on the r a t e of c h l o r i n a t i o n of iron and n i c k e l in C12 (Ref. 1) and HC1 (Ref. 2). In the p r e s e n t i n v e s t i g a t i o n the r a t e of c h l o r i n a t i o n of NtO, Fe20 S and NiFe204 in C12 (1073 to 1473 K) and NiO and Fe,O s in HC1 (1073 to 1273 K) has b e e n d e t e r m i n e d . The r a t e s were m e a s u r e d as a function of t e m p e r a t u r e , gas c o m p o s i t i o n , p a r t i c l e size and p o r o s i t y of the oxides. The f r e e e n e r g i e s for the c h e m i c a l r e a c t i o n s 8 i n v e s tigated for NiO a r e : S i O ( s ) + C12(g ) = NiC12 (g) + 89
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[1]
AF = 36,520 - 31.13 T ( c a l o r i e s ) S i O ( s ) + 2HC1 (g) = NiC1 s (g) + nsO(g)
[2]
~u~ = 19,160 - 12.55 T ( c a l o r i e s ) In the c h l o r i n a t i o n of Fe20 s to a v o l a t i l e c h l o r i d e t h e r e a r e s e v e r a l p o s s i b l e p r o d u c t s : FeC12 (g), FeCI~ (g), and Fe2C16 (g). The m o s t f a v o r e d t h e r m o d y n a m i c a l l y for the conditions of this i n v e s t i g a t i o n is FeC13(g). The r e a c t i o n s and f r e e e n e r g i e s 8 a r e : Fe~O 3 (s) + 3C12 (g) = 2FeC1 s (g) + ~ O2 (g)
[3]
AF = 65,210 - 47.95 T ( c a l o r i e s ) Fe2Os(s) + 6HCI(g) = 2feC13(g ) +3 H20(g )
[4]
AF = 15,130 + 6.81 T ( c a l o r i e s ) R. J. FRUEHAN and L. J. MARTONIKare Senior Scientist and Research MetallurgicalAnalyst, respectively, Research Center, U. S. Steel Corporation, Monroeville,Pa. 15146. Manuscript submitted February 15, 1973. METALLURGICALTRANSACTIONS
The f r e e e n e r g y change a c c o m p a n y i n g the c h l o r i n a t i o n of NiFe204 in C12 is given by: 8 NiFe204 (s) + 4C12 = NiC12(g) + 2 F e C l s ( g ) + 202(g) AF = 111,210 - 85.16T ( c a l o r i e s ) In i n v e s t i g a t i n g the r a t e of r e a c t i o n of a p o r o u s m a t e r i a l with a gas it is i m p o r t a n t to e x a m i n e the r a t e as a function of p a r t i c l e s i z e . A c o n v e n i e n t method of r e p r e s e n t i n g t h e s e r e s
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