Thermodynamic investigations on chalcopyrite

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The CuFeSx.6s, CuFeSx.7, and CuFeS~.8 s a m p l e s were s y n t h e s i z e d by r e a c t i o n of s u l f u r with a s p e c i a l l y p r e p a r e d c o p p e r - i r o n t w o - p h a s e alloy. T h i s c o p p e r - i r o n alloy was p r e p a r e d by s t e a m a t o m i z a t i o n of a 20-1b m e l t at I n d u s t r i a l M a t e r i a l s Technology, Inc., of M a s s a c h u s e t t s . The technique i n v o l v e s quenching a s t r e a m

I. EXPERIMENTAL 1. M a t e r i a l s The composition of the s e v e n e x p e r i m e n t a l s a m p l e s and t h e i r mode of p r e p a r a t i o n a r e given in T a b l e I. F o u r of these lie within the chalcopyrite phase field at the t e m p e r a t u r e of m e a s u r e m e n t while the o t h e r t h r e e s a m p l e s a r e i n the b o r n i t e + c h a l c o p y r i t e t w o - p h a s e field, the p y r r h o t i t e + c h a l c o p y r i t e two-phase field, and the chalcopyrite + b o r n i t e + p y r i t e t h r e e - p h a s e field. The copper u s e d was v a c u u m cast, s p e c i a l high purity grade obtained f r o m the United States M e t a l s Refining Company; e l e c t r o l y t i c m e l t i n g stock i r o n d e s c r i b e d as s u p e r p u r i t y grade was obtained f r o m the Glidden Company, Metals Division; s u l f u r was obtained as l u m p s of 99.999+ pct p u r i t y from the A m e r i c a n S m e l t i n g and Refining Company. The b o r n i t e , supplied by E. G. King of the Bureau of Mines, was s y n t h e s i z e d f r o m the e l e m e n t s at about 670~ and the p r e p a r a t i o n h a s been d e s c r i b e d in detail. 2 J. PAUL PEMSLER is Group Leader, Chemistry Kennecott Copper, Ledgemont Laboratory, Lexington, Mass. 02173. CARL WAGNERis Senior Staff Member, Max-Planck-Institutfi~r BiophysikalischeChemic, GOttingenNikolausberg,Germany. Manuscript submitted July 22, 1974. METALLURGICALTRANSACTIONS B

Fig. 1--700~ isothermal section after Yund and Kullerud1 (ep = chalcopyrite; bn = hornite; po = pyrrhotite; py = pyrite).

Fig. 2--Portion of 700"C isothermal section including bornite and chalcopyrite compositions after Yund and Kullerud. 1 VOLUME 6B, JUNE 1975-311

Table I. Preparation of Sulfide Samples

Compositionof Sample

Reactants

CuFeSI.62

Cu-Fealloy+ S

CuFeS1.7

Cu-Fealloy+ S

CuFeSl.8 CuFeSI.9

Cu-Fealloy+ S CuFeSI.8 + S

bornite + chalcopyrite "Cu~.22 Feo.TsS~.57" chalcopyrite + bornite + pyrite "CuFeS1.22" chalcopyrite + pyrrhotite

CuFeS~.7+ bomite CuFeS~.9+ S CuFeSl.7+ Feo.gsS

"Cuo.67 Fe l.ss S 1.s3"

Temp of Sulfur Sample Reservoir Temp ~ ~ 400 500 380 425 400

750 700 600 600 620 620 480 700

370 420 550 700 grind,then 700 990 72

Time Hrs 48 96 24 72 390 44 16 960 44 21 90 168 168 4 700

of m o l t e n m e t a l with a jet of s t e a m and r e s u l t s in a r a n g e of fine p a r t i c l e t w o - p h a s e alloy; a p h o t o m i c r o graph is shown in F i g . 3. The fine d i s p e r s i o n of c o p p e r and i r o n i n s u r e a r e l a t i v e l y r a p i d e q u i l i b r a t i o n d u

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