The effect of sodium chloride on the dissolution of chalcopyrite under simulated dump leaching conditions

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The Effect of Sodium Chloride on the Dissolution of Chalcopyrite Under Simulated Dump Leaching Conditions J . E. DUTRIZAC AND R. J . C. MacDONALD U N D E R dump leaching c o n d i t i o n s , c h a l c o p y r i t e (CuFeS2) d i s s o l v e s v e r y slowly 1 and the e c o n o m i c a l a c c e l e r a t i o n of this d i s s o l u t i o n is d e s i r a b l e . R e c e n t s t udi es 2 i n d i c a t e that s t r o n g l y o x i d i z i n g c h l o r i d e solutions ( e . g . , c h l o r i n e w a t e r ) g r e a t l y a c c e l e r a t e the d i s s o l u tion of CuFeS2 u n d e r s i m u l a t e d dump l e a c h i n g c o n d i tions. U n f o r t u n a t e l y , such r e a g e n t s a r e r e l a t i v e l y e xp e n s i v e ; by c o n t r a s t , the addition of a few g r a m s p e r l i t e r of c o m m o n salt (NaC1) would be r e l a t i v e l y i n e x p e n s i v e . Although r e c e n t work 3 i n d i c a t e d that the p r e s e n c e of c h l o r i d e ion can a c c e l e r a t e the d i s s o l u t i o n of p u r e c o p p e r s u l f i d e s , the effect of c h l o r i d e ion on the d i s s o l u t i o n of l o w - g r a d e c o p p e r sulfide lump o r e u n d e r l o w - t e m p e r a t u r e / l o n g - t i m e conditions has not been i n v e s t i g a t e d . Th u s, it was d e c i d e d to i n v e s t i g a t e the effect of NaC1 on the r a t e of d i s s o l u t i o n of c h a l copyrite under simulated dump-leaching conditions.

PELLET

LEACHING

EXPERIMENTS

The f i r s t s t e p in this study was to a s c e r t a i n the e f f e c t of NaC1 on the d i s s o l u t i o n of p u r e synthetic c h a l c o p y r i t e in a c i d i f i e d f e r r i c s u l f a t e so l u t i o n s u n d e r c o n t r o l l e d e x p e r i m e n t a l conditions. Th e c h a l c o p y r i t e s y n t h e s i s , p e l l e t p r e p a r a t i o n , and r o t a t i n g disk leaching p r o c e d u r e w e r e d e s c r i b e d p r e v i o u s l y . 4 The l e a c h i n g so l u t i o n s c o n t a i n e d 0.1 M F e ยง [as Fe2(SO4)a], 0.1 M H2SO4, and 0, 1, o r 6 g p e r l i t e r NaC1. T h e s e e x p e r i m e n t s w e r e done at 80~ and 200 r p m d i s k - r o t a t i o n speed. F i g . 1 i n d i c a t e s that NaC1 i n c r e a s e s the r a t e of c o p p e r e x t r a c t i o n f r o m the synthetic CuFeS2. A f t e r 22 hr of l each i n g , the p r e s e n c e o