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D. N. THATCHER,

AND

J. D. MILLER

The rate of e x t r a c t i o n of copper (II) from acid n i t r a t e solutions with LIX 64N was studied in a single drop r e a c t i o n cell in which e x p e r i m e n t a l conditions were c o n t r o l l e d so that the back r e a c t i o n k i n e t i c s were u n i m p o r t a n t . U n d e r these conditions the e x t r a c t i o n r e a c t i o n was found to be f i r s t o r d e r with r e s p e c t to the cupric ion concentration, half o r d e r with r e s p e c t to the c o n c e n t r a t i o n of the a - h y d r o x y oxime component of LIX 64N, and half o r d e r with r e s p e c t to the c o n c e n t r a t i o n o f the hydroxy-benzophenone oxime component of LIX 64N. Detailed c o n s i d e r a t i o n of the e x p e r i m e n t a l r e s u l t s and the h y d r o d y n a m i c s of a f a l l i n g drop s y s t e m s u g g e s t s that a s u r f a c e r e a c t i o n m e c h a n i s m is rate c o n t r o l l i n g and that the r e a c tion r a t e is not l i m i t e d by m a s s t r a n s f e r . The apparent a c t i v a t i o n enthalpy of a p p r o x i m a t e l y 6.5 k c a l / m o l e (27.2 k J / m o l e ) was found to be e s s e n t i a l l y independent of the v a r i a b l e s considered.

S I N C E 1963 when G e n e r a l M i l l s i n t r o d u c e d LIX 63 as a s e l e c t i v e e x t r a c t a n t for copper, m a n y i m p o r t a n t d e v e l o p m e n t s have taken place in the a r e a of copper s o l v e n t e x t r a c t i o n . A m o n g these d e v e l o p m e n t s has b e e n the m a r k e t i n g of a s e r i e s of o t h e r e x t r a c t a n t s , the f i r s t of which was LIX 64, followed by LIX 64N, I.XX 65N, LIX 70, LIX 71 and LIX 73. E q u i l i b r i u m s t u d i e s and the c o m p o s i t i o n s of LIX 63, LIX 64, LIX 64N and LIX 70 have b e e n d i s c u s s e d in a p r e v i o u s publication.1 B r i e f l y , LIX 64N, the e x t r a c t a n t of p a r t i c u l a r c o n c e r n in this p r e s e n t i n v e s t i g a t i o n , is a m i x t u r e of about 1 pct LIX 63, an a - h y d r o x y oxime, about 45 pct LIX 65N, a benzophenone oxime, with the b a l a n c e being i n e r t compounds s i m i l a r to k e r o s e n e .

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LIX 65N

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LIX 65

2R65~org ) + Cu~{aq) --R26SCU(org) + 2H+(aq)

R26SCu,would

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R. k ATWOODis Assistant Professor of Metallurgy,Universityof Idaho, Moscow, Idaho; D. N. THATCHER is Director of Research, McCormick-Teledyne,Holtister, California;and J. D. MILLER is Associate Professor of Metallurgy, Universityof Utah at Salt Lake City, Utah 84112. Manuscript submitted February 11, 1974. METALLURGICALTRANSACTIONSB

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R65Cu

C2H 5

The s t o i c h i o m e t r y of the e x t r a c t i o n r e a c t i o n was shown to be c o n s i s t e n t with that r e p o r t e d in the l i t e r a t u r e and the o v e r a l l r e a c t i o n can be r e p r e s e n t e d by the following equation:

w h e r e the e