Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a fireproof, gas-
permeable construction module for blowing gases through
the outer lining of metal treatment containers.
The oxygen blowing methods for purifying pig
iron material are improved from the metallurgical
standpoint by blowing secondary gases such as nitrogen
or argon into the converter under controlled conditions
through the bottom of the converter. Also, in methods
involving the blowing of oxygen through the bottom as
well as in metal treatment containers, such as furnace
pans, desulfuring pans and the like, the blowing in of
gases into the metal bath through the container bottom
or the lining of the container walls is taken into
consideration.
The gas-permeable stones which are used in
the lining of such containers must meet the requirement
that their durability matches the durability of the
remainder of the fireproof lining since the exchanging
of used-up gas-permeable stones in a hot condition is
a difficult operation Furthermore, it is desirable
that the gas feed be possible both continuously and in
particular discontinuously, that is, the container
should be operable without the gas feed and, after
restoring the gas supply, the stones should be gas-
permeable in an unchanged manner. Furthermore, thetas permeability of the stones should remain approxi-
mutely the same throughout their use, that is, through-
out the total operation of the furnace.
In Canadian Patent Jo. 1,1~6,599 of May 17,
1983, Applicants have disclosed a device which may be
inserted in the bottom of a metal treatment container
for blowing a treatment gas into a metal bath. This
prior art device has a good durability and permits the
blowing in of the desired quantity of gas. The device
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consists essentially of a fireproof, gas-permeable
structural module including a plurality of metallic
separating members of a low wall thickness which are
embedded in an axial direction into the fireproof
material of the unit. The separating members have a
flat, corrugated, pipe-like or wire-like configuration.
In accordance with one embodiment, this prior art
structural module consists of steel sheet metal plates
and segments, or of strips made of fireproof material
in an alternating arrangement.
- For making such structural modules, it has
been necessary to cut a prefabricated block made from
fireproof material into the required strips or segments
and this cutting operation turns out to be a very
expensive method. Segments made of compressed fire-
proof material, due to their low thickness and large
length, are inconvenient to manipulate and also, unless
subjected to a firing, are prone to shrink.
Applicant has improved such fireproof modules
(Canadian Patent No. 1,177,643 issued November 13, 1984)
by making the segments in press-molds, whereby the metal
layers are pressed together with the fireproof material.
Thus, the abutting longitudinal faces of the segments
can be made with a smooth or profiled surface, for
example, or with a corrugated or a grooved surface.
When assembling the segments provided with
the profiled metal layers, there result joints, channels
and the like in the structural element through which the
gas is supplied, whereby the profiled longitudinal faces
may rest on a smooth as well as on a profiled longitu-
dial face of the adjoining segment. The engaging
longitudinal face of the adjacent segment may be
provided with a molded-in metal layer, or the latter
; may be dispensed with. Also, pairs of superposed metal
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inserts, such as for example sheet metal plates, may
be embedded in the individual segments. Spacers may
be installed between the metal plates of one pair of
inserted elements.
Fireproof structural modules of the
aforedescribed type operate successfully if one uses
argon or nitrogen as a rinsing gas. Unfortunately,
argon is a very expensive gas. Pure nitrogen is less
expensive but dissolves at very high temperatures in
liquid steel, thus impairing steel quality.
Attempts have been made to blow through
the previous stones different gases into the con-
venter, for example carbon dioxide, whereby a rapid
deterioration of the fireproof stones was noticed
and the fireproof mass crumbled already after a few
charges. Furthermore, it was noticed that the
deterioration of the fireproof material took place
mainly at the hot side of the structural module. The
prevailing temperature at the hot side apparently
causes reactions like C02 + C = CO, the C-atoms
originating from the carbon containing binding
material of the fireproof mass. In addition, it is
also believed that further reactions occur, like
C2 + Moo = MgO3. This also would explain the
crumbling of the stone mass.
It is an object of the invention to
provide an improved refractory gas-permeable struck
tubal module or unit including elements which do not
substantially react with the rinsing gas used even
if the latter has an oxidizing effect.
In accordance with the present invention,
there is thus provided a refractory gas-permeable
structural unit for blowing gas into a metallurgical
vessel through its lining, comprising at least two
elements having a core of refractory non-porous
material, the elements abutting against one another
with their longitudinal faces a common metal
housing surrounding the longitudinal faces of the
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elements with at one of the end faces of the unit,
at least one gas connection and a gas distribution
chamber. The structural unit according to the
invention is characterized in that the elements are
provided at least on all their longitudinal faces
with a gas-tight cover.
The structural unit of the invention
permits the blowing into the converter of any gas
which under normal operating temperature does not
react with the selected protective cover. Therefore,
the exact composition and the grain structure of the
refractory mass of the unit are of less importance.
The refractory mass gives support to the
protective cover and in addition avoids an excessive
heating of the same due to deflection of -the heat to
the cold side of the structural unit. One of the
most important characteristics of the refractory
material is a low expansion coefficient which is
adjusted to that of the protective cover, so as to
eliminate premature formation of cracks in the
structural unit. Suitable refractory materials are,
for example, tar-bound sistered magnesium, high-
alumina-content material or mixtures of magnesium
and chrome ore.
Further features and advantages of the
invention will become more readily apparent prom the
following description of preferred embodiments
thereof as illustrated by way of examples in the
accompanying drawings, in which:
FIG. 1 is a perspective view of a refract
tory structural unit according to the invention; and
FIGS. 2-6 are sectional perspective views
of the individual segments which may be used in the
module of FIG. 1.
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The structural unit 1 illustrated in FIG.
1 includes a metal housing 10 made of welded plates
and enclosing a total of twelve segments 3 which are
disposed in two columns. Each segments is provided
with protective metal plates, 4, pa on all four
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longitudinal sides The sheet metal plates are
corrugated on two longitudinal sides, while the other
two sides of the sheet metal plates are flat. The
segments are arranged in such a manner that a Corey-
grated sheet metal plate pa of each segment is in contact with a flat sheet metal plate 4 ox the
adjoining segment. In order to prevent bulging of
metal housing 10, no corrugated plates pa face the
walls of the housing. A central sheet metal plate 5
can be inserted between the two columns of segments 3
so that gas can pass along the plate 5 as well as along
the metal plates 4, pa of respective segments 3. The
segments are spaced apart from the front edges of the
metal housing by means of two bars 6 which are mounted
on the inside of metal housing 10, preferably by spot
welding. At this region which represents the cold
side, a front plate 7 is tightly welded on the housing
and is provided with a pipe connection 8. The free
space between the front plate 7 and the front sides of
segments 3 is the distribution chamber for the gas.
In this embodiment, fireproof mass 9 at the
cold front side of segments 3 is covered with a protect
live sheet metal plate (not shown). On the cold side
of the structural module, temperatures between 300 and
400C are present, at which carbon dioxide, for example,
attacks the fireproof mass only very slowly; never the-
less, a protective coating is still of advantage. The
opposite side, not visible in the drawing, represents
the fire side of the structural module and can be
closed with a sheet metal cover. The latter is used
when the metal treatment container which surrounds
the structural module, contains tar or similar carbon
containing materials. During the heating of the
treatment containers, it serves to prevent the penes
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traction of tar or the like into the gas-permeable joints
of the structural module or the cementing of the same.
The sheet metal cover melts at the start of the operation
and opens the passages between the joints.
In an advantageous modification of the module
illustrated, there are arranged only three superposed
segments 3 in the housing 10. The five protective sheet
metal plates covering one of the segments are all of
flat configuration (plates 4) whereas at the two
remaining segments only one longitudinal side of each is
covered by a corrugated plate pa and the three remaining
sides as well as the cold front side are again covered
by flat plates 4. The three segments are arranged in
housing lo in such a manner that none of the corrugated
plates contacts the inner wall of the housing.
FIG. 2 illustrates a segment 23 whose fire-
proof mass 29 is covered on all four lateral sides as
well as on the cold front side with flat steel plates
24. The flat sheet steel plates 24 are provided with
longitudinal metallic strips 22, the strips on opposite
sides being staggered. The strips can be fixed to the
sheet metal plates by spot welding. The extent of the
gas permeability can be varied by the thickness of these
strips. however, the strips should not be too thick,
so as to permit the operation of the structural modules
even without a gas supply. In the latter case, some
metal will penetrate in the tight slot between the
segments, however, when restarting the gas supply, this
penetrated metal is rinsed off from the structural
module and the original gas permeability is restored.
Issue surprising effect occurs only if the strips of
sheet metal are not excessively thick.
In the segment 33 illustrated in FIG. 3, the
fireproof mass 39 is surrounded by sheet metal plates 34
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which are provided with longitudinal arresting ribs 32.
The ribs 32 ma be simply rolled into the sheet metal
plates. The ribs on opposite sides of the module are
staggered relative to each other
FIG. 4 illustrates a segment 43 whose fire-
proof mass 49 is covered on all sides with steel plates
44. The gas passage in this embodiment primarily occurs
through longitudinal grooves 42 which are milled into
the sheet metal plates.
In the segment 53 illustrated in FIG. 5, the
fireproof mass 59 is covered at all sides with flat
sheet metal plates 54. The distance between two
segments is adjusted by means of a manlike structure
So made of steel wool, which acts as a spacer. Spacers
in the form of metal bands or wires may also be used.
In the aforedescribed embodiments steel sheet
material is used as a protective layer for the fireproof
mass. For this purpose, the sheet metal is rolled into
the desired shape, cut into the desired size, bent and
welded.
Another preferred embodiment of the invention
is illustrated in FIG. 6. Fireproof material is first
introduced into a press-mold, The mold shapes the fire-
proof material with the arresting bars, grooves or
corrugations. After a short thermal treatment which
may be required in order to solidify the material, the
longitudinal rectangular blocs of material are provided
with a protective coating.
The liquid used for the coating may be a
metal paint with a ceramic binding material or a
ceramic paint, for example. The two segments 63
illustrated in FIG. 6 have a coating 64 which is made
by immersing the corrugated fireproof material 69 into
a metal paint bath. Depending on the metal paint used,
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the segments after the immersion are tempered It may
be eventually necessary to repeat the immersion-temper
process a few times until the desired thickness of the
coating has been reached,
It will be understood what the elements
described above may also find a useful application in
other types of constructions differing from those
described above
While the invention has been illustrated
and described as embodied in a gas-permeable construe-
lion element for use with metal treatment containers,
it is not limited to the details shown, since various
modifications and structural changes may be made
without departing in any way from the spirit of the
present invention
