The distribution of silver, gold, platinum and palladium in metal-matte systems
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n u m b e r of s t u d i e s have been made which r e p o r t quantitative m e a s u r e m e n t s of the d i s t r i b u t i o n of im~ p u r i t i e s between the m o l t e n , i m m i s c i b l e phases, m e t a l and m a t t e , c o e x i s t i n g d u r i n g copper s m e l t i n g . In t e r m s of e l e m e n t s studied, the m o s t c o m p r e h e n s i v e i n v e s t i gations have b e e n those of Asano and c o w o r k e r s who c o v e r e d Se, Te, Sn and Zn; ~ As, Sb and Bi; ~ Pb and Ni, and t h e i r i n t e r a c t i o n s ;s and Au, Ag and a r e v i s e d value for Se. 4 F o r the m o s t p a r t , these m e a s u r e m e n t s were made u n d e r conditions which do not c l o s e l y a p p r o x i mate those o b s e r v e d in actual copper o p e r a t i o n s . F o r e x a m p l e , all data w e r e obtained at a single t e m p e r a t u r e (1200~ and c o m p o s i t i o n (sulfur s a t u r a t e d copper and cuprous sulfide) with s a m p l e s e q u i l i b r a t e d in e v a c uated c a p s u l e s . F u r t h e r m o r e , the i m p u r i t y c o n c e n t r a tions g e n e r a l l y v a r i e d f r o m 0.5 to 10 wt pct, a r a n g e well above the one found in n o r m a l p r a c t i c e . Some of these e l e m e n t s , p a r t i c u l a r l y Se and Te, have also been studied u n d e r conditions m o r e c l o s e l y a p p r o a c h i n g those found in typical s m e l t e r s . Schlitt and l~ichards s have made l a b o r a t o r y s t u d i e s on both Se and Te d i s t r i b u t i o n as a f u n c t i o n of t e m p e r a t u r e (1100 to 1250~ i m p u r i t y c o n c e n t r a t i o n (0.01 to 0.4 wt pct), c o m p o s i t i o n ( c o p p e r - c o p p e r sulfide plus 0 to 50 wt pct FeS) and a t m o s p h e r e (purified N z and g a s e s c o n t a i n i n g both Oz and SO,). On a l a r g e r s c a l e Baker and Hallowes 6 have p e r f o r m e d i n - p l a n t s t u d i e s on the b e h a v i o r of Se and Te in b l i s t e r c o p p e r - w h i t e m e t a l m e l t s weighing up to four tons. A r e c e n t i n v e s t i g a t i o n of nickel d i s t r i b u t i o n has also b e e n r e p o r t e d . 7 The purpose of m o s t of these p a r t i t i o n i n g s t u d i e s has b e e n to d e t e r m i n e whether or not the p r e f e r e n t i a l d i s t r i b u t i o n of the v a r i o u s t r a c e e l e m e n t s is sufficient to cause them to c o n c e n t r a t e to a high degree in the m e t a l o r the matte. Whenever this is the case t h e r e is a d i s t i n c t p o s s i b i l i t y of r e m o v i n g or r e c o v e r i n g the highly c o n c e n t r a t e d i m p u r i t i e s d u r i n g converting, r a t h e r than in s e p a r a t e e l e c t r o l y t i c o r f i r e r e f i n i n g o p e r a t i o n s . The e x p e r i m e n t a l method used for i n v e s t i gating the potential of such a s e l e c t i v e r e f i n i n g t e c h nique has been to m e a s u r e the d i s t r i b u t i o n or p a r t i tion coefficient Ki for the i m p u r i t y in question. W. J. S
