Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
This invention relates to monolithic
refractory conduits and more particularly to such
conduits beinq formed ln situ for use with molten
metals such as steel for the "bottom pouring"
process of forming ingots.
Refractory shapes for containing molten metal
are well known in the art and have been in use
since the earliest days of molten metallurgy.
However, because of the extremely high tempera-
tures of some molten metals (e.g., steel), such
shapes have been liable to breakage because of
severe thermal conditions imposed by such high
temperatures. Moreover, the materials from which
lS such shapes are made must be carefully selected in
order to avoid entraining impurities and poisoning
the molten metal through the formation of
undesired ingredients such as slag. Also, steel
breakout through the joints between these shapes
is a major problem.
Clay type materials have been used
extensively to provide refractory linings for high
temperature molten metals. However, because of
the particular characteristics of such materials,
it has been conventional to form the refractories
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in bricks, tiles or other discrete shapes and then
piecing them together to form the desired
refractory assembly. Thus, for example, it is cus-
tomary to use refractory bric]cs for lining
S furnaces and ladles, and discrete tubular shapes
are pieced together in sections to form tubular
conduits of the desired length.
Problems associated with the piecing together'
of tubular shapes to form tubular conduits of
needed length have been particul~rly acute in that
branch of the steel making art that is known as
"bottom pouring". As generally used in the steel
making arts and as employed in this specification,
the term "bottom pouring" connotes the conveying
of molten steel into a mold from or through its
bottom. Typically this has been accomplished to
improve surface quality of certain grades of
steel, although bottom pouring is also practiced
in steel making facilities for which continuous
casters are not economical. It is also attractive
for use,in the maXing of special grades of steel.
In such instal~ces, the refractory shapes required
for conductinq molten metal from its source to the
bottom of the mold must be joined tightly to pre-
vent leakage while the liquid steel is being con-
ducted-from the conduit through holes in the
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bottom of the mold. Such conduits have heretofore
been fabricated with individual shapes which are
then joined together to create the completed
structure. However, it has been found that
despite care in fabrication and care in surround-
ing the conduit with appropriate void-filling
particulate materials, such conduits are normally
vulnerable to fracture or joint leakage with the
attendant loss of molten steel and/or other
undesired consequences. Moreover, since it is not
practicable to flush molten steel from the conduit
and to recover it while it is in its molten state
at the end of the pour, the steel still remaining
in the conduit solidifies and the conduit must be
removed for extraction of the steel, thereby
requiring the reconstruction of the conduit each
time a pour is made.
BRIEF_ SUMMARY OF T13E. INVENTION
In accordance with the instant invention, the
disadvantages of the prior art are substantially
overcome in that the aforementioned conduit is
constructed in one monolithic piece which is
substantially less expensive both to produce and
install. According to the invention a discardable
shape is employed as an internal form about which
a monolithic refractory lining is produced by
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spraying/grouting of a monolithic refractory mate-
rial preferably comprised of fire clay, magnesia,
and/or high-alumina material. Steel tubing, hard
cardboard tubing, or the like may be employed as
the form about which the refractory material is
applied Such a form is sacrificed and is
liquified, vaporized or burned up during dry out
or when molten steel is introduced to the interior
of the refractory conduit. Moreover, sinCe the
monolithic refractory material is applied in a
viscous or slurry condition, a variety of shapes
to fit required circumstances can readily be
prepared, thus simplifying manufacture and reduc-
ing time and expense.
OBJECTS AND FEATURES OF THE INVENTION
It is one general object of this invention to
improve the fabrication of molten`metal conducting
conduits.
I~ is another object of this invention to
reduce costs and simplify construction or
fabrication of such conduits. ~ -
It is still another object of the invention
to facilitate the on-site preparation of odd
shaped refractory conduits.
It is yet one other object of the invention
to reduce problems associated with the joining of
refractory segments in refractory conduits.
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. Accordingly, in accordance with one feature
of the invention, a sacrificial form is employed
to define the desired internal shape of the
conduit and a monolithic refractory material
slurry or similar viscous mixture is applied to
the exterior of the form, thereby facilitating the
production of monolithic metal conducting conduits
of substantial length.
In accordance with another feature of the
invention, particular compositions of fireclay,
magnesia, and/or high-alumina refractory materials
are advantageously employed in slurry form,
thereby imparting qualities of.dependability to
the finished product.
These and other objects and features of the
invention will be apparent from.the following
detailed description of preferred embodiment of
the invention, with reference to the drawings.
BRIEF SUMMARY OF THE DRAWINGS
Figure 1 illustrates a typical configuration
which hçretofore been employed in the bottom
casting of steel;
Figure 2 illustrates a typical installation
of refractory conduit by which the molten steel is
conducted from its source into the bottom interior
of the ingot molds;
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Figure 3 is a partial plan and partial
sectional view of a typical "spider" shape and
conduit configuration of the prior art;
Figure 4 is a cross-section taken through a
port of Fiyure 3; and
Figure 5 is a view depicting the principal
components of the equipment employed to practice
the principles of the instant invention.
DETAILED DESCRIPTION
Now turning to the drawing, and more
particularly to Figure 1 thereof it will be
observed that it discloses a partially sectioned
elevation view of conventional apparatus of the
prior art employed to perform the bottom pouring
of steel. Typically, such apparatus comprises a
foundation for the e~uipment which is known in the
art as a bottom plate. Such bottom plate is iden-
tified with the designating symbol 10.
Within bottom plate 10, there is provided a
recessed area 11, which may be partially filled
with any suitable substance such as sand 12. This
material forms a convenient leveling bed for the
refractory shapes and in addition to providing
some general thermal insulation qualities, more -
importantly provides intimate contact with the
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"molten metal conducting conduit" and its associ-
ated parts to ensure the shapes are held firmly in
place and in compression during the pouring of
molten steel.
The ingot mold 13 is seen to include side
walls 14, and the entire ingot mold is typically
fabricated of cast iron by known techniques.
Mold 13 is typically anchored on the bottom
plate 10 by methods well known in the art for such
purpose. In addition, mold 13 is seen to include
a conventional hot top 16 which is positioned at
the upper portion of the mold and is included so
as to provide a suitable transition from the
extreme heat of the mold interior to the outer
ambient. Such hot top may also provide a con-
trolled rate of cooling so as to prevent excessive
heat loss from the upper surface of the molten
metal prematurely and prevent undesired
characteristics that may result from premature
solidification. As will be observed from Figure
1, such hot top may be made of any suitable
refractory material well known in the art and may
be positioned atop the mold side walls 14, by any
suitable means such as wood blocks 17.
At the right side of Figure 1 there ls dis-
closed a conventional vertical member generally
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known in the industry as a "down-fountain" or
"center runner" 18. Such down-fountain provides
for the introduction of moltenl steel from any
suitable means such as a ladle into refractory
funnel 19 and thence downwardly through vertical
interior conduit 20 formed by re~ractory shapes
21. The supporting structure 2a for these
refractory shapes is cast iron.
The funnel 19 and its associated vertical
section is supported in known fashion by anchoring
flange 23 to the bottom plate 10, thus imparting
structural stability.
The inte;rior of conduit 20iis connected to a
horizontal mating conduit 24 which includes
15 refractory walls 25 and interior channel 26. -
Thus, when molten steel is introduced to the pour-
ing funnel 19 at the top thereof, it can be con-
ducted vertically down channel 20 and thence
horizontally through channel 26 to the bottom of
mold 13.
~ -will be observed from further reference to
the ~igure, horizontal unit 24 is comprised of
discrete segments such as segments which are con-
nected together by abutting or adjoining sections
te.g., 30, 31). As mentioned above it is the
segmentation of the vertical conduit 21 and the
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horizontal conduit 24 that is at least partially
responsible for the high costs of installation and
the vulnerability to conduit rupture.
Within the upper portions of the sections of
conduit 24 which underlie mold 13, (e.g., sections
27, 28, and 29) are located outlets 40, 41, 42 ~nd
43. These outlets communicate from the interior
opening 26 of horizontal conduit 24 to the inte-
rior 44 of ~old 13. Accordingly, molten steel
introduced into the pouring funnel 19 is conducted
through channels 20 and 26 and thence through
apertures 40 - 43 to the interior 44 of mold 13,
thus providing for conventionaL bottom introduc-
tion of molten steel for bottom pouring.
Now turning to Figure 2, there is therein
depicted a dual mold figuration wherein molds 50
and 51 are provided with bottom entry ports 52 and
53 through which molten steel is conducted to the
interior of the molds from horizontal metal-
conducting conduit 54. Thus, Figure 2 illustrates
a configuration for simultaneous filling of a
plurality of molds, a feature which is
conventional of the prior art. However, Figure 2 ;
illustrates monolithic walls 55 and 56 which are
illustrative of one form of the instant invention
in which the conduit walls have been
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advantageo~sly fabricated in accordance with the
principle~ hereof. Although the .~upporting mate-
rials 57 and 58 are conventional ~e.g., cast iron)
and well known in the art; and although the walls
59, 60, 61 and 62 of molds 50 and 51 are also
conventional (e.g, cast iron~ it will be under-
stood by those skilled in the art that they may be
constructed of other conventional materials.
Figure 3 illustrates another form of molten
metal-conducting conduit construction known in the
steel making arts as a "spider". ~ere, the molten
metal is conducted downwardly within circular
conduit 65 and exists at the bottom thereof
through conventional ports into the interior con-
ducting channel 66, 67, 68 and 69 whence it is
conducted laterally to positions beneath molds
(not shown) and introduced thereto through verti-
cal orfiices similar to 52 and 53 of Figure 2.
Figure 3 is included to illustrate the some-
what irregular shapes that moltel~ metal conducting
conduits sometimes take. Thus, for examplej mem-
ber 70 which includes interior conducting channel
66, includes one right angle bend 71 and an acute
angle bend 72. Other irregular shapes are com-
monly encountered in the art, and it will beevident to one skilled in such art that require-
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ments of bottom pouring often times require diffi-
cult to fabricate geometries.
Figure 4 is a section ta~;en alon~ the lines
4-4 of Figure 3 and illustrates the preferred form
for the molten metal conduction through conduit
formed in accordance with the principles of the
invention. Vertically standing circular conduit
65 is defined by refractory walls 73 formed by any
suitable refractory material well known in the :
art. Moreover, in isome instances, such refractory
may be formed in accordance with the principles o
the instant invention. In such case, the interior
form which as described above -is made of any suit-
able material such as steel or cardboard-like
material, disappears when dried out or when the
first flow of molten metal is introduced thereto
and consequently such form is not shown in Figures
3 or 4. .
As with conventional down-fountains, the
refractory support is cast iron casing 74 which is
anchore~ by conventional methods to base plate 76.
It is now evident that in order to
efficiently practice known methods of bottom pour-
ing for high temperature molten metals, there is a
need for a way to fabricate the liquid metal con-
ducting conduits so as to provide such conduits
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that have a high degree of rellability and protec-
tion against rupture while at the same time being
susceptible of being readily formed in any of a
variety of shapes. Accordingly, in accordance
with the principles of the instant invention, such
molten metal conducting conduits can readily be
fabricated in a simple and cost effective way.
Figure 5 illustrates the preferred method of
forming the aforementioned molten metal conducting
conduits. In this Figure is shown a store of
refractory ~aterial ~0, a hopper 81 for receiving
such material, a vertical passageway 82 havin~ a
material controlling gate 83, a metering chamber
84, a mixing chamber 85 for mixing the material
with a fluid such as water, mixed material hopper
86, pump 87 and flexible hose 88 leading from pump
87 to nozzle ~9.
Also depicted in Figure 5 are controls 90
which are provided in the conventional way to con-
trol the flow of materials and the output of pump87. Such controls are well known in the art and
provide for remote control by an operator (not
shown) positioned near nozzle 89 by which he can
control the flow rate of the mixture of refractory
materials (e.g., slurry) exiting from nozzle 89.
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Figure 5 also depicts a platform cart 91 ha~-
ing conventional wheels, 92 which support cart bed
93 on which there is supported a bottom plate 94
such as that described above ~hich is in place and
ready for forming the runner refractory in situ.
As mentioned above, suitable examples of preferred
materials are steel tubing and cardboard. Of
course, as mentioned above, other corresponding or
equivalent materials may be readily employed while
practicing the invention.
In practicing the principles of the
invention, the aforementioned refractory mix is
expelled from nozzle 89 and is shown as grout or
spray pattern 95. The grouted or sprayed material
95 surrounds the exterior of form 94 and fills the
space within the channel of the~bottom plate 94.
Excess material above the top of the channel is
trowelled to produce a level surface even with the
top of the plate. The plate i5 then heated to dry
out the monolithic refractory.
It-has been found that a preferred refractory
material for practicing the inventive concepts
hereof is a material generally known in the steel
making arts of DOSSOLITE 1400-72. As is known to
2~ those skilled in the art, the composition of
DOSSOLITE 1400-72 is approximately:
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Silica (Si~2) 16.0%
Alumina (A123) 1.5
Iron Oxide (Fe23)
Lime ~CaO) ~.0
5 Magnesia ~MgO~ 75.0
Other oxides 3.5
TOTAL10 0 %
Refractory conduits in ac~cordance with the
aforementioned described procedures can be formed
using such material as described in the following
example. However, other types of refractories
which are compatible with clean steelmaking also
can be used.
The invention will be further described in
connection with the following example which is set
forth for purposes of illustration only.
EXAMPLE
A monolithic ref~actory lining for the down-
fountain or center runner is formed separately
from the horizontal runners in the bottom plate.
Down-Fountain
. . .
The iron casting has a series of 1/8" diame-
ter weep holes spaced evenly around its perimeter
and over its entire length. These will allow
steam escape during dryout. "Ceramic paper" at
lJ16" thickness is placed around the inside wall
of the iron casing to act as a wick to facilitate
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dryout and then removal of the refractory
monolithic lining after use. Next, a light gauge
steel or cardboard mandrel at 4-1/2" O.D~ is cen-
tered and supported within the casting by means of
end members. Vsing the equipment shown in Figure
5, DOSSOLITE 1400-72 is pumped into the cavity
between the mandrel and walls of the casting until
this void is filled completely with DOSSOLITE.
The entire down-fountain is then placed in an oven
to thoroughly dry out the DOSSOLITE slurry. If
cardboard is used for the mandrel, it must be
burned out or charred during dryout to eliminate
any hydrogen pickup in the liquid steel. A number
of down-fountains can be prepared in this manner
at one time. After use, the DOSSOLITE will shrink
upon cooling for easily removal and reuse of the
iron casting.
Horizontal Runners
A conventional "spider" shape is first set
into the appropriate cavity in the bottom plate.
A 2-15/i6" O.D. mandrel of thin gauge steel pipe
or cardboard is set in each of the channels. One
end of the mandrel is placed into the outlet of
the "spider" shape, and the other end is centered
and supported by means of a jig set into the
channel. ~sing the equipment shown in Figure 5,
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DOSSOLITE ls sprayed or pumped into the channel
starting at the end next to the "spider" shape.
After the mandrel is sufficiently anchored into
place with DOSSOLITE, the jig can be removed so
that the entire channel can be filled with
DOSSOLITE. The DOSSO~ITE is then trowelled to
even it with the top of the bottom plate. Th~
slurry is then dried out by placing a burner into
the inlet of the "spider" shape so that the hot
gases exhaust through the runners and out the
risers. Because the cast iron bottom plate is
thermally conductive, it can also be heated using
gas torches to facilitate dryout. If a cardboard
mandrel is used, it must be heat treated as it was
for the down~fountain. After this arrangement has
been used, the DOSSOLITE will shrink in the chan-
nel upon cooling. The solidified steel and used
refractory conduit are removed from the bottom
plate in the conventional manner.
It will now be evident that there has been
described herein an improved refractory conduit
and the methods of fabricating the same, which
product and method exhibit significant advantages
over the corresponding art. Although the
inventive concepts hereof have;been illustrated by
way of a preferred embodiment, it will be evident
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to those s~illed in the art that adaptations and
modifications may be employed without departing
from the spirit and scope of the invention. :
The terms and expressions used herein are
employed as terms of description and not of
limitation; and there is no .intent in the use
thereof to exclude equivalents, but on the
contrary, it is intended to include all
e~uivalents, adaptations and modifications that
may be employed without departing from the spirit
and scope of the invention as defined in the
claims.
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