In-place leaching of primary sulfide ores: Laboratory leaching data and kinetics model

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e s t s y s t e m is shown s c h e m a t i c a l l y in Fig. 1. The v e s s e l is made of type A-36 s t e e l and is i n t e r n a l l y lined with 5/32-in. c h e m i c a l lead. The l i n e r is t r e a t e d with dilute H2SO4 to provide a l a y e r of PbSO4 and thus e l i m inate f u r t h e r i n t e r a c t i o n with HaSO4 produced during the leaching phase. The s a m p l i n g p r o b e s , t h e r m o c o u ple sheaths, and oxygen inlet pipe a r e made of C a r p e n t e r - 2 0 s t a i n l e s s steel. The t e m p e r a t u r e of the solution within the autoclave is maintained to within + 2~ of the d e s i r e d o p e r a t i n g t e m p e r a t u r e by e x t e r n a l e l e c t r i c a l h e a t e r tapes beneath the insulation. The gas inlet p r e s s u r e is r e g u l a t e d , and the flow of gas through the s y s t e m is c o n t r o l l e d by a needle valve to give the d e s i r e d flow r a t e as indicated by the p r e s s u r e drop a c r o s s a known o r i f i c e at the gas exit. The s m a l l e r s y s t e m s of c a p a c i t y 0.5 to 20 l i t e r s A Oxygen supply

I

B Pressure regulator

d Thermocouple

C Check valve D Oxygen in le t

K Liquid sampling tube L Liquid retention cylinder

E Air-cooled condenser

M Liquid e xit

F Pressure r e l i e f valve and pressure gauge G Filter H Needle valve

N Liquid adit 0 Ore level P Liquid level

--

Flowmeter

HE

~1.3

m

3.]m

Leaching e x p e r i m e n t s w e r e conducted in autoclaves ranging in c a p a c i t y f r o m 0.5 to 3800 l i t e r s . The l a r g R. L. BRAUN and A. E. LEWIS are Members of AIME, and are Scientists at Lawrence Livermore Laboratory, Livermore, California. M. E. WADSWORTH is a Member of AIME, and is Professor of Metallurgy at University of Utah~ Salt Lake City, Utah. 94550. Manuscript submitted November 26, 1973. METALLURGICAL TRANSACTIONS

Fig. 2 Fig. 1--Diagram of r e a c t o r for e x p e r i m e n t Exp-L1. Fig. 2--Diagram of s m a l l r e a c t o r . VOLUME 5, AUGUST 1974-1717

a r e shown s c h e m a t i c a l l y in Fig. 2. The v e s s e l is made of s t a i n l e s s s t e e l lined with c h e m i c a l lead and is heated e x t e r n a l l y . The sampling probe, thermo-" couple sheath, and oxygen inlet tube a r e made of t i t a nium. These s y s t e m s have a p r o v i s i o n for r e m o v a l of liquid s a m p l e s for c h e m i c a l a n a l y s i s during the c o u r s e of the r e a c t i o n without disrupting the o p e r a t i n g t e m p e r a t u r e or p r e s s u r e . Ore Type The o r e used in these e x p e r i m e n t s is a p r i m a r y p o r p h y r y c o p p e r o r e f r o m the San Manuel Mine (Magma Copper Company, Arizona). The m i n e r a l a s s e m blage, d e t e r m i n e d by X - r a y diffraction and optical m i c r o s c o p y , is p r i n c i p a l l y quartz and s e r i c i t e , with minor amounts of f e l d s p a r , c h l o r i t e , b i o t i t e , calcite, c h a l c o p y r i t e , and p y r i t e . In addition, t h e r e a r e t r a c e amounts of h e m a t i t e ,