Note: Descriptions are shown in the official language in which they were submitted.
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COMBINATION ELECTRIC FURNACE AND SLAG RETAINI~G POURING SPOUT
Backg _und of the Invention
Technical Field:
This invention relates to electric furnaces and more particu-
larly to electric furnaces with means producing better quality
steel by tapping slag-free.
Description of the Prior Ar-t:
Prior electric furnaces have utilized bottom tapping in
an effort to deliver a slag-free steel, such as described for
example in the article spanning pages 66-69 in the April 1984
issue of Metal Producing. A continuous pouring furnace tiltable
to deliver molten metal from sidewardly positioned tap holes
is disclosed in Patent 2,458,236 and an apparatus for separating
slag from molten metal i.s disclosed in Patent 2,360,065.
The present invention combines an effective new and novel
slag retaining spout with an electric furnace and places the
spout in registry with a piped angular tap hole in the electric
furnace resulting in the ability of the new combination to
de].iver slag-free molten steel so important in today's highly
competitive market and essential when the molten me-tal is
processed by a corltinuous caster.
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Summary of the Invention
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A combination electric furnace and a slag retaining pouring
spout on an end wall of the electric furnace in communication
with a piped angular tap hole arranges the slag retaining pour-
ing spout in an angular configuration with respect to the endwall in which the tap hole is located and provides a consumable
tap hole plug in a secondary tap hole in the pouring spout, the
arrangement of the slag retaining pouring spout being such that
such slag as initially enters the pouring spout is retained
above the molten metal therein until the consumable tap hole
plug is dislodged whereupon the further tilting of the electric
furnace and the slag retaining pouring spout thereon insures
the delivery of slag-free steel therefrom. At the time the
tapping of the electric furnace is substantially completed,
the further tilting of the electric furnace and the slag retain-
ing pouring spout acts to deliver the molten slag through a
sideward extension of the pouring spout so as to insure the
separation of the slag from the previously poured slag-free
steel.
Description of the Drawings
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Figure 1 is a vertical section through the combination
electric furnace and slag retai.ning pouring spout showing
the device in initial -tapping position;
Figure 2 is an enlarged section on line 2-2 of Figure l;
Figure 3 is an enlarged detail of a lever arm and flap
gate arranged ior registry with the secondary tap hole seen
in Figure l; and
Figure 4 is a vertical section of the combination electric
furnace and slag retaining pouring spout in the position in
which the electric furnace is operating.
Description of the Preferred Embodiment
In its preferred form, the combination electric furnace
and slag re-taining pouring spout is illustrated in the
vertical section of Figure 4 of the drawings in its operational
posi-tion refining steel, the electric furnace including a
vessel comprising a. shell 10 and a refractory lining 11, the
vessel having oppositely disposed ends 12 and 13 and a remov-
able l.id 14 as customary in the electric furnace art. The lid
14 is provided with a refractory lining 15 and apparatus, not
shown, movably mounts a plurality of electrodes 16, also as
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known in the art.
The vessel is arranged for pivotal motion on a transverse
axis so that the end wall 12 will move downwardly in various
degrees, one of which is illustrated in Figure 1 of the
drawings. Directional arrows in Figures 1 and 4 of the
drawings indicate such movement.
A piped tap hole 17 is angularly positioned through the
end wall 12 and a slag retaining pouring spout 18 is attached
to the end wall 12 o~ the shell 10 of the electric furnace
vessel and in communica-tion with the piped angular tap hole
17. The slag retaining pouring spout is formed of a secondary
shell 19 and lined with a refractory liner 20, the shell 19
and liner 20 being substantia]ly U-shaped in cross section,
as shown for example in Figure 2 of the drawings.
A cover 21 is positioned over the slag retaining pouring
spout 18 and is provided with an opening 22 through which a
closure, sometimes known as a dart (not shown), may be
positioned to close off a secondary tap hole 23. Ports
24 in the cover 21 are provided for the injection of Argon
gas if required. Additionally, the slag retaining pouring
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spout 18 has a slag removal opening 25 in its upper outermost
end, in that portion which is disposed at an angle with
respect to the portion of the sl.ag retaining pouring spout
attached to the shell 10 of the electric furnace vessel.
In Figure 2 of the drawings, a sub.stantially vertical
section on line 2 to Figure 1 illustrates the substantially
U-shaped cross sectional configuration of the refractory liner
20 of the slag retaining pouring spout and a sideward extension
26 having a similar U-shaped refractory liner 27 which communi-
cates with the slag removing opening 25 as hereinbefore
described.
In Figure 2 of the drawings, a consumable tap hole plug
28 is illustrated in the opening 25. By referring again to
Figure 4 of the d-rawings, it will be seen tha-t the vessel
forming the electric furnace is illustrated in its normal
operating condition wherein electric arcs are maintained
between the electrodes 16 and the molten metal M therein, it
being understood that the electrodes ~6 are electrically
connected with a suitable source of electrical current as
will be understood by those skilled in the art.
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The refining of the molten metal M, for example steel,
results in the ~roduction of slag indicated by the let-ter S
so that a pool of molten steel M with the layer of molten
slag S thereon lies below the piped angular tap hole 17 of
the electric furnace and it will be unde~stood that when
the steel is ready-for tapping, the vessel comprising
electri.c furnace with the attached slag retaining pouring
spout 18 is tilted so that the end wall 12 moves downwardly
to the position illustrated in Figure 1. Initially there will
be some flow of the molten slag S through the piped angular
tap hole 17 and a small amount will accordingly flow into
the slag retaining pouring spout 18. As the vessel formi.ng
the electric furnace continues to tilt to the position shown
in Figure 1, the molten metal M, such as steel, will then flow
through the piped angular tap hole 11 into the slag retaining
pouring spout 18 which will be retained therein.in the pocket
formed by the angular configuration of the slag retaining
pouring spout 18 as best shown in Figure l of the drawings.
The secondary tap hole 23, which is located in the
0 slag retaining pouring spout 18, is initially closed by a
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consumable tap hole plug, such as known in the art, and the
life oI the tap hole plug in -the secondary tap hole 23
is such that it will not permit the molten slag in the
slag retaining pouring spout 18 to flow downwardly through
the secondary tap hole 23. As the vessel comprising the
electric furnace continues to tilt,the molten metal, such as
steel., flows into -the slag retainil-g pouring spout 18 and lifts
the layer of slag above the secondary tap hole 23 and -the con-
sumable plug therein. The consumable plug disin-tegrates and
the mol-ten steel can then flow downwardly throu~h the secondary
tap hole Z3 into a receiving vessel such as a ladle, not shown.
In Figures 1 and 4 of the drawings, a flap gate comprising
a closure 29 on the end of a lever arm 30 will be positioned
in open relation rather than closed as illustrated in Figures
1 and 4 of the drawings. At the termination of the tapping of
the desirab].e molten metal, such as steel,and before the
slag M has reached the secondary tap hole 23, the closure
29 on the lever arm 30 is moved to closed position as shown
in enlarged detail in Figure 3 of the drawings, thus stopping
the flow of the metal and preventing the contamination of
the tapped metal by the slag S. At thi.s time, the vessel
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comprising the electric furnace is tilted to a greater degree
than illustrated in Figure 1 of the drawings, whereupon the
slag will flow into and out of the slag removal opening 25
from which the consumable tap hole plug has been removed.
Such s]ag is directed to a slag pot or like disposal receptacle,
as will be understood by those skilled in the art.
By referring again to Figures 1 and 3 of the drawings,
it will be seen that a tap hole brick 31 defines the actual
secondary tap hole 23 and that the closure 29 pivoted to
an end of the lever arm 30 is arranged to engage the tap
hole brick 31. It will also be seen that surrounding the
lower portion of the tap hole brick 31, an Argon shroud 32
is provided. The Argon shroud is a circular structure of a
diameter greater than the closure 29 and has means for receiving
Argon gas from a suitable source. The outer wall of the
circular Argon shroud 3~ is preferably provided with circum-
ferentially arranged, substantially vertically extending
corrugations so that the lower edge of the shroud forms a
plurality of closely spaced, jet-like openings communicating
with an enlarged annular area thereabove into wh:Lc~ tne Argon
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gas is introduced. The downward flowing cixcular pattern of
Argon gas as formed and directed by the Argon shroud 32
protects the slag-free metal flowing through the secondary
tap hole 23 from atmospheric contamination and the like.
It will occur to those skilled in the art that the
principal point of novelty in the present disclosure is the
combination of the vessel of the electric furnace with the
slag retaining pouring spout affixed thereto and communicating
therewith by way of the piped angular tap hole 17. This
construction and the particular angular relation of the
portions of the slag retaining pouring spout 18 and its
relation to the end wall 12 of the electric furnace vessel
will be seen to make possible the tapping of slag-free metaI,
such as steel, from the electric furnace.
It will also occur to those skilled in the art that
when the ma~or portion of the metal being tapped has moved
through the secondary tap hole 23 in the slag retaining pouring
spout 18, the closure 29 on the lever arm 30 may be used to
stop such flow or alternately a closure, such as known in the
art as a dart, may be introduced into the secondary tap hole
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23 in the slag retaining pouring spout 18 -through the opening
22 in the cover 21 thereof as heretofore explained.
The first portion of the pouring spout 18 adjacent the
furnace is disposed at an angle of about 10 from horizontal
and the outer or second portion of the pouring spout 18 disposed
at an angle of about 50 from horizontal. The angularly
disposed tap hole 11 in the furnace is disposed at an angle
of about 35 from horizontal and the secondary tap hole 23
is located in the bottom of the pouring spout at the junction
of the two angular portions thereof.
It will thus be seen -that a combination electric furnace
and slag retaining spout formed thereon has been disclosed
and having thus described our invention, what we claim is:
