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Kemi
Tab 4. Reaction temperatures (°C) and reacted CaO in per cents by weight of entire CaO-quantity.
Mixtures Thermal
treat-ment of mica or feldspar before reaction (preheating) 500 600 700 750 800 850 900 1000 1100 1150
CaO 4- Mica (mus- 600° 1 h. 5,6 6,4 10,0 18,6 31,8 57,7 92,0
covite), molar „ 5 )) 9,8 10,5 12,9 — 20,0 — 40,3 68,3 96,2 —
CaO 1 800" 1 3,7 4,0 4,4 — 7,2 — 14,1 27,6 52,5 85,6
ratio ^rpr- = T S102 1 5 3,3 3,3 4,0 — 6,2 — 13,6 30,9 60,1 89,0 |
1 000° 1 Jf 1,0 —1 1,8 5,6 16,1 — 40,8 61,7 79,0 _
»> 5 „ 3,0 3,8 — 4,1 5,7 — 16,5 26,0 32,0 —
CaO + Feldspar 600° 1 11. 1,8 1,8 1,9 _ 3,2 _ 12,3 35,3 65,0 —
(orthoclase) » 5 t) 1,6 1,7 1,8 — 2,8 — 10,3 32,2 57,9 —
molar ratio 800° 1 >> 2,1 2,1 2,4 — 3,8 — 15,2 41,4 71,5 —
CaO 1 „ 5 2,2 — 2,5 — — 8,2 — 39,9 68,6 —
SiOa 1 1000° 1 5,1 5,1 5,2 — 6,2 14,0 25,1 48,4 74,3 —
» 5 » 5,0 5,2 — — 6,2 12,6 23,1 46,2 68,4 —
of the amount of Si02 and of H,0, which latter
re-mains in small quantities in the muscovite
preparations even after long preheating at 600°. The results
are given as yield curves showing the reacted CaO in
per cent by weight of the entire CaO quantity.
E. CaO + muscovite (Table 4, Fig. 7*).
There appears neither a maximum ön the curves
nor any other irregularities which arè of interest in
this connection. In general the preparations,
pre-heated at lower temperatures, show the largest
reactivity. Above about 800° the preparation, preheated
at 1000° for 1 hour, shows a very high reactivity,
which rapidly decreases if the preheating time is
pro-longed (Musc.!000/5 h.)- These circumstances shall not
be discussed in this connection because the reactivity
of different kinds of mica will be treated in a special
investigation. It is sufficient to point out that ön the
one hand the runs of the curves Musc-xooo/ih. and
Musc-i ooo/ö h. evidently show that the maximum effect
ön the corresponding
= j have a very regular course without any
bi02 1
geometrical irregularities. No other discussion of the
curves will be made in this connection. As could be
expected the reactivity of orthoclase with CaO is
smaller than that of mica. Thus the influence of the
feldspar impurity ön the reactivity of the VA, YG and
VL preparations is still smaller than that of the mica.
Reaction experiments with sillimanite and mullite.
G. Sillimanite (Table 5 and 6, Fig. 9 A, B).
The reaction properties of sillimanite are of great
importance to applied oxide chemistry because of its
röle as a raw material for different kinds of
refrac-tories. In this paper we shall limit ourselves to
results which will give some information about the
reactivity of sillimanite, which has been heated to
kaolin curves YA, VG
and VL; (Pho contains
no mica) is not produced
or influenced by the
reactivity of the mica
and that, ön the other
hand, such an influence
may be expected only
at higher temperatures,
in some cases perhaps
already at about 800°
F. CaO + orthoclase
(Table 4, Fig. 8*).
The yield curves
corresponding to mixtures
of CaO+orthoclase with
* These curves show the
quantities of reacted CaO in
per cent by weight of total
CaO and not in molal
proportions between reacted
CaO and the other reaction
component (as is the case
in fig. 3—6, 9, 10) because
of the complexity of the
latter in these mixtures.
Reacted CaO in per cent by weight of entire CaO-quantity
100
m
Reaction temp. °C
Fig. 7.
8 nov. 1941
25
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