Solubility of nitrogen and carbon in esr type slag
- PDF / 277,716 Bytes
- 3 Pages / 603.28 x 783.28 pts Page_size
- 19 Downloads / 208 Views
have b e e n r e p o r t e d p r e v i o u s l y . 1'~ F u r t h e r , the Ca, A1, F c o n t e n t s w e r e d e t e r m i n e d in o r d e r to check w h e t h e r changes in the Ca : A1 : F r a t i o s o c c u r r e d d u r i n g the long r e a c t i o n t i m e s . The t y p i c a l c o n c e n t r a t i o n t i m e c u r v e s a r e shown in F i g . 1. Z e r o point of the t i m e s c a l e i s at the t i m e when the c a r b o n monoxide a t m o s p h e r e was changed to the N 2 - C O - A r gas m i x t u r e . In the u p p e r d i a g r a m the c o n t e n t s of total n i t r o g e n (N)total , of c y a n i d e (CN) and of total c a r b o n (C)total a r e shown. The acid s o l u b l e c a r b o n c o n t e n t s a r e i d e n t i c a l to t o t a l c a r b o n c o n t e n t s , within the s c a t t e r of the p o i n t s . Hence, the a m o u n t s of graphite in the slag are negligibly small, and there is no indication that a reaction of the type 2Coz- = C4- + 3C (graphite) occurs in these slags during solidification as has been found to occur in CaC2-AI203 melts.8 Similarly as in the previous experiments with CaO-A1203 melts I~ the curves for (C)total and (CN) have maxima. The decrease of the (C)total and (CN) contents at long reaction times is caused by the change in the Ca and A1 contents of the slag (see lower diagrams in Fig. 1). Due to volatilization of Ca containing species, the CaO/AlzO3 ratio of the slag becomes smaller with increasing time and this is associated with a slight decrease of carbide and cyanide solubilities, Corresponding curves were obtained for all the other experi-
I
I
I
I
I
I
PC0 = 050tm , pN2= 010tm 038-
(C)totol
o
S
l
o
o o~lr"-'--------~0 o
o
(CN)
020z
-~ 010-
/
9
(N)totot
o tote[ carbon o acid so ub[e carbon 0
42 @ O
9
41 =
I
@
I I
~0 18
17" 15 lg 9
17
lb
z~
3'0
4'0
I
5'0
f,'o
7b
80
reaction time, h KLAUS SCHWERDTFEGER and HANS GEORG SCHUBERT are with Max-Planck-Institut fi~rEisenforschung GmbH, Metallurgical Department, Max-Planck-Strasse 1,4000 Di~sseldorf,Germany. Manuscript submitted March 14, 1977. METALLURGICAL TRANSACTIONSB
Fig. 1--Typical results on compositional changes occurring in slag of nominal 32 wt pct CaO, 32 wt pct A1~O3, 36 wt pet CaF 2 during equilibration with graphite and Ne-CO-Ar gas mixture (1600~ 1 atm). VOLUME 8B, DECEMBER 1977-689
ments. The values f o r (N)total, (CN), (C)total, as obtained in the various e x p e r i m e n t s , a r e listed in Table I. The c h e m i c a l r e a c t i o n s f o r the f o r m a t i o n of nitride, cyanide, and carbide can be written as 3 0 2_ (slag) + ~3 C (graphite) + ~1 N2 (gas) 3
= N s" (slag) + ~ CO (gas)
[1]
1 0 2_ (slag) + ~3 C (graphite) + g1 N2 (gas) = CN- (slag) + ~1 CO (gas)
[2]
Table I. Exper mental Results on Solubility Measurements With 32 Wt Pct CaO, 32 Wt Pct AI=O~, 36 Wt Pct CaF= (Graphite Crucible, 1600~ 1 Atm) Kcyanid e PN~,
PCO,
PAr,
(N)total
'
(C/V),
(C)total
Atm
Atm
Atm
Wt Pct*
Wt Pct*
Wt Pct*
0.05 0.10
0.50 0.50
0.45 0.40
0.25~
0.50~
Data Loading...
