The hydrolysis of cupric amines
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ChemicalAnalysis,Pct Sample C4A3S Ct~A7
Al~O3 SiO~ 13.l 13.1
17.7 19.2
CaO 54.1 57.3
Extraction, Pct
Fe203 803 1.90 1.65
4.83 0.09
A1203
SiO2
93.9 31.7
1.56 1.55
I00
T h e m a j o r d i s a d v a n t a g e of t h e C4A3~ s i n t e r p r o c e s s is the f o r m a t i o n of Na2SO4 d u r i n g the l e a c h i n g r e a c t i o n . CaSO4 is r e a d i l y l e a c h e d with Na2CO3 to f o r m CaCOs and Na2SO4. CaSO4 + Na2CO3 = CaCO3 + Na2SOa.
F u r t h e r m o r e , Na2SO4 w i l l not l e a c h AlzO3 f r o m l i m e st o n e o r C4A3S s i n t e r s . Na2SO4 could of c o u r s e be u s e d in the P e n i a k o f f r e a c t i o n [9] to p r o d u c e NaA102 which is s o l u b l e in H20. 2A1203 + 2Na2SO4 + C = 4NaA102 + 2SO2 + CO2.
~'"~-S -'N I TERN I G_TEMPERATURE ~ 6o ~ 40
~"
SN I TERCHEMC I AALNALYSIS(~) 10.3 21.151,2 3.61 6.9T
2c
SINTERING TIME AT TEMPERATURE,MINUTES
Fig. 2--Relative rates of C4A~wformation for coat waste/ limestone/C aSO4 sinters. t r a c t i o n with l e a c h i n g t i m e s a s s h o r t a s 1 min; w h e r e a s , C12A7 has b e e n shown to r e q u i r e at l e a s t a 30 rain l e a c h .
The Hydrolysis of Cupric Amines I. G. R E I L L Y AND D. S. S C O T T When o r e s s u c h as c h a l c o c i t e , c o v e l l i t e , o r b o r n i t e a r e l e a c h e d in an e x c e s s of a m m o n i a u n d e r o x i d i z i n g c ond i t i o n s , low y i e l d s m a y be obtained u n l e s s an a m m o n i a s a l t is a l s o p r e s e n t . In r e p o r t s of l e a c h i n g s t u d i e s , t h i s low d e g r e e of e x t r a c t i o n has s o m e t i m e s b e e n a s c r i b e d to an a n io n d e f i c i e n c y . ' While this f a c t o r m ay be one c a u s e of r e d u c e d y i e l d s , s o m e p r e l i m i n a r y r e s u l t s we have obtained i n d i c a t e that t h e r m o d y n a m i c r e a s o n s a l s o a c c o u n t f o r s o m e of the reduced yield. T h e c a s e of c o v e l l i t e (CuS) is p a r t i c u l a r l y i n t e r e s t ing, as t h i s o r e c o n t a i n s the s t o i c h i o m e t r i c r e q u i r e m e n t of s u l f u r to a l l o w f o r m a t i o n of th e s o l u b l e c u p r i c t e t r a m i n e , and in p r i n c i p l e should d i s s o l v e 100 pct in o x i d i z i n g a m m o n i a s o l u t i o n without added a n i o n s. H o w e v e r , S t a n c z y k and R a m p a c e k ~ found that high y i e l d s could not be o b t a i n e d with c o v e l l i t e e v e n at long r e a c t i o n t i m e s and high t e m p e r a t u r e s . When a m m o n i u m s u l f a t e was added, h o w e v e r , n e a r l y c o m p l e t e dissolution was achieved.
I. G. REILLY is Assistant Professor, School of Engineering, Laurentian University, Sudbury, Ontario, Canada. D. S. SCOTT is Professor, Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada. Manuscript submitted December 1, 1975. 718-VOLUME 7B, DECEMBER 1976
[8]
[9]
C o a l w a s t e s h a v e high NazO l o s s e s when l e a c h e d as NaA102 s i n t e r
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