RAW MATERIALS
PETROGRAPHIC ANALYSIS OF CONTEMPORARY
REFRACTORY VANADIUM SLAGS
1
V. A. Perepelitsyn,
2
A. L. Smirnov,
3
L. A. Smirnov,
3
and V. A. Rovnushkin
3
Translated from Novye Ogneupory, No. 7, pp. 17 – 22, July 2009.
Original article submitted April 17, 2009.
MICROSTRUCTURE OF VANADIUM SLAGS
Industrial slags
The microstructure of the overwhelming majority of
specimens as a whole is fundamentally similar and it has the
following common features:
– approximately 50 – 60% of the area (volume) of the
microstructure is occupied by isometric crystals of spinelid
whose size varies within wide limits, i.e. from 10 to 100 mm
(see Table 2);
– discrete crystals of spinelid are cemented by a continu-
ous silicate matrix consisting of two or three silicate phases;
– a two-phase silicate matrix is often encountered and it
is an aggregate growth of fayalite and glass phase;
– a three-phase silicate binder consists of fayalite,
pyroxene and glass phase with a clear predominance of crys
-
talline minerals;
– the appearance of the porous texture is variable: from
almost pore-free monolithic to highly porous pumiceous
with a pore size from several mm to 5 mm;
– the morphology of spinelid crystals is idiomorphous
(entirely faced) or in combination with oval, sometimes ir
-
regular, corroded (sometimes all forms of crystals even in
one polished section);
– fayalite is variable in shape, i.e. from regular tablet
with rectilinear faces to skeletal and dendritic;
– pyroxene has two structure-heterogenic varieties: pri
-
mary, crystallizing from a melt, in the form of edged crystals
between crystals of fayalite and secondary, solid phase,
forming during firing of glass phase (by a sitallization mech
-
anism for Ti-containing silicate glasses);
– precipitates of glass phase have an irregular shape
since it fills the space (interstices) of all other crystalline phases;
– in all specimens in a variable amount there is a metal
phase (iron) with sizes of micro-inclusions from several mi-
crons to tens of millimeters;
– the content of metal inclusions is from 1.5 to 8.0 vol.%;
– secondary (impurity or accessory) minerals, repre-
sented by products of oxidation of vanadium spinelid and
fayalite at a pore surface, consist of a thin film of glass of sil-
ica composition with inclusions of haematite Fe
2
O
3
,
clinoenstantite MgSiO
3
, pyroxene of the type CaO×MgO×2SiO
2
,
and other silicates;
– perovskite CaTiO
3
forms thin (1 – 3 mm) lamellar and
acicular skeletal crystals in glass phase.
On the basis of detailed structural-genetic and physico
-
chemical analyses of the microstructure of specimens of in
-
dustrial vanadium slags the following features of mineral
formation have been established:
– a constant chronological sequence of crystallization of
phases: vanadium spinelid ® fayalite ® pyroxene 1 ® pe
-
rovskite ® glass phase ® [pyroxene 2 + residual glass];
– a sequence of phase precipitation correlates with their
melting temperature (apart from perovskite);
– glass phase is a more complex polyphase component
readily-melting residual melt with a high content of FeO,
MnO, CaO, Al
2
O
3
, and SiO
2
and increased viscosity;
– during solidification of glass phase perovskite CaTiO
3
(T
m
= 1970°C) crystallizes from it, probably vanadium-con
-
taining with the formula Ca(Ti,V)O
3
;
Refractories and Industrial Ceramics Vol. 50, No. 4, 2009
252
1083-4877/09/5004-0252 © 2009 Springer Science+Business Media, Inc.
1
Conclusion. For beginning of the article see Novye Ogneupory
No. 5 (2009).
2
OAO Eastern Institute of Refractories, Ekaterinburg, Russia.
3
OAO Ural Institute of Metals, Ekaterinburg, Russia.
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