Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2Q82836
Process and Device to Avoid Contamination
of Ta~ping Steel by Flush Slag with
a Tiltable Converter
Description
This invention concerns a process and a device to
avoid, or rather prevent, contamination of tapping steel
by flush slag with tiltable converters.
Tiltable converters have a discharge opening located
at a suitable spot in the converter wall above the bath
level through which liquid steel is transferred into the
tap ladle. In order to empty the converter, it is tipped
into such a position that the steel flows through the
discharge opening into the ladle. Since specifically
lighter slag of various viscosities is always found on the
molten metal, it first passes into the tap hole during the
tilting process and thus varying quantities of flush slag
end up in the tap ladle. The presence of oxygen-rich slag,
frequently enriched with phosphorous or sulphur, is dis-
advantageous for numerous subsequent metallurgical pro-
cesses. This results in the demand that converter steel be
transferred to the tap ladle as free of slag as possible.
This is preferably achieved by plugging the tap opening of
the converter temporarily.
2482836
2
In this regard, a number of systems are known which
are supposed to open the tapping channel only when the
slag has passed the tapping channel during the tipping
process. In particular, slide systems are known as closing
mechanisms; but they cannot prevent flush slag entering
the tapping channel. In addition, up to now stoppers made
of various materials or combinations of materials have
been placed outside in the tap opening or driven into it.
Combinations of fibrous materials with solid bodies,
plastic clay materials, wooden stoppers, and also pitch
stoppers are used for the external placement and, for the
internal placement, combinations of sheet metals coated
with fireproof materials and sheet metal claws which are
supposed to dig into the tapping channel as described in
DE 39 38 687 C2.
The technically required conical or funnel-like shape
of the tapping channel and the progressive wear of the
fire-proof material in this area results in the premature
breakdown of the stopper protection against flush slag
contaminants, so that the behaviour of the stoppers cannot
be controlled and, therefore, they are a negative factor.
Consequently, fairly large quantities of flush slag are
frequently transferred into the ladle.
The problem of this invention is to present a flush
slag stopper and a process which reliably prevents large
quantities of converter flush slag from being transferred
into the ladle.
208283fi
3
This problem is solved by using a suitable setting
device to push a highly plastic, fire-resistant material
into the tapping channel from the outside up to the area
of transition to the inside of the converter and com-
pressing it with the help of the setting device and a
compressing plate made of heat-resistant materials
attached to the stopper to such an extent that the diam-
eter of the tapping pipe is completely filled in.
As a result of this working method, the geometric
shape of the tapping channel, especially age-related
tapping channel enlargements, are of secondary importance
to the functioning of the stopper.
In the inventive application, the stopper, which
conforms in its fire-proof composition and plasticity to
the occurring operating conditions, adheres instantaneous-
ly to the tapping channel wall, so that immediately after
placement the stopper sits firmly in the tapping channel
directly in the area of transition to the interior of the
converter. On account of the high interior temperatures in
2o the converter, within a short time the fire-proof material
forms a sintered cap a few centimetres thick on the side
facing the interior of the converter which can bear the
blast pressure and the occurring vibration and shaking. In
particular, the time at which the stopper is placed in the
tapping channel in accordance with the invention in order
to exercise its protective function is of secondary
importance. Even after the flush stopper has been in the
tapping pipe for several hours, the different operating
processes and conditions of a converter have no negative
~~~2~3~
4
effect whatsoever on its full functioning and protective
effect. Due to its placement in the area of transition to
the interior of the converter, the penetration of slag
into the tapping channel during the blast process, which
occurs frequently with newly lined converters, is also
effectively prevented. In addition, the permanent and
temporary binding agents contained in the f ire-proof
material of the flush stopper prevent the rest of the mass
decomposing prematurely.
The cap formed towards the interior side of the con-
verter is stable enough to direct the slag securely past
the tapping channel when the converter is tipped. It col-
lapses only when exposed to the ferrostatic pressure.
Because the material adjacent to the tapping channel wall
is not sintered, it is completely removed within a short
time by the outflowing steel.
The fact that large masses of fire-proof material is a
disadvantage of other stopper systems as mentioned in DE
39 38 687 C2 is not supported by the inventive fire-proof
2o material mentioned. For the inventive process mentioned,
merely a mass of ca. 2 - 3 kg fire-proof material is
required to provide complete protection, even with conical
tapping pipes larger than 20 cm in diameter.
The fire-proof material may be made of raw materials
based on suitable compositions of silicon, aluminium, and
magnesium oxides or silicates. Insulating alumosilicate or
magnesium silicate as well as quartz materials in a grain
size less than 3 mm are preferred.
20~2~36
In a preferred embodiment of the invention, the f ire-
resistant material should have the following composition:
- alumosilicate, insulating 20 - 40~ by weight
- bonding clay 20 - 40~ by weight
- water 0 - 30~ by weight
- mineral oil 5 - 20~ by weight
- plasticizer 0.1 - 0.5~ by weight
- liquifier 0.1 - 0.5~ by weight
- temporary binders/celluloses 0.1 - 0.5~ by weight
- permanent binders/silicates 1 - 2.5~ by weight.
This fire-resistant material has a density by volume
of 0.8 - 0.9 kg/dm3 and, therefore, is considerably lighter
than the materials traditionally used for this purpose.
The compression plate used is made of heat-resistant
material and may have any geometric shape suitable for
this purpose. In a preferred embodiment of the invention,
it is funnel-like in shape and has a funnel channel extend-
ed through the stopper. Among other things, this channel
serves as a guide for the setting tool to compress the
stopper and to centre the exiting stream of molten metal
at the moment of the tapping ~in order to avoid the shower
effect of the flowing steel. The funnel channel can have
various diameters. In the case of the inventive embodiment
used, the diameters are 25 - 38 mm; they may, however,
also be larger or smaller, and the entire funnel channel
may be conical. The cross-section of the funnel channel
may deviate from the circular shape.
2082836
(a)
In one broad aspect, the present invention relates to a
device for sealing the taphole of a tiltable converter with
a sealing plug (8) which is made of a heat-resistant
5 material, a faceplate (2) directed towards the inside of the
converter (9) which melts on contact with liquid steel and a
jigging device by which the sealing plug (8) can be inserted
into the taphole (10) and can be moulded therein against its
wall, whereby the sealing plug (8) comprises a cylindrical,
plastic core (1) covered by a faceplate (2) and a base plate
(4) which are connected with the jigging device displaceably
towards one another, characterised in that the faceplate (2)
is designed passing into a funnel channel (5) which
penetrates the sealing plug or core (1) and is designed to
receive a drawing claw (6) acting on the faceplate.
In another broad aspect, the present invention relates
to a process for operating a converter and for the even and
slag-free removal of the liquid steel, whereby a sealing
plug made of plastic is inserted into the taphole connecting
the inner wall and outer wall up to the height of the inner
wall of the converter in the taphole and is then moulded by
means of a jigging device from its side averted from the
inner wall and also from its side facing the inner wall
until it fits tightly against the hole wall, the sealing
plug is positioned by means of the jigging device in the
transition zone in relation to the converter inner chamber
opening a funnel channel passing therethrough by squeezing,
whereby the plastic material of the plug is made of
20 to 40 wt % insulating aluminosilicate
20 to 40 wt % binding clay
0 to 30 wt % water
5 to 20 wt % mineral oil
0.1 to 3 wt o plasticizer, e.g., polyelectrolyte
alcohols
A
202836
(b)
0.1 to 2 wt % liquefier, e.g., fatty acid
0.1 to 2 wt % temporary binding agent, e.g.,
cellulose and
5 0.1 to 5 wt % permanent binding agent, e.g.,
silicates
is mixed to form a fire-retardant with a density of 0.8 to
0.9 kg/dm3, formed into a cylindrical body and is then
penetrated by the funnel channel of a funnel-shaped squeezer
plate, fitted onto the jigging device, inserted into the
t....,~.,~., .. "~.~ ~,.,.."~.."a
A:
6
A preferred embodiment of the invention is explained
below, the diagrammatic illustrations being as follows:
Fig. 1 a lateral perspective view of an embodiment through
a slag flush stopper,
Fig 2 a section through an object in accordance with Fig.
1 and positioning in the tapping channel of a converter,
Fig. 3 a section though a configuration following the
insertion and compressing of the object in accordance with
Fig. 1.
to The flush stopper illustrated in Fig. 1 is cylindrical
in shape. The cross-section of the stopper need not be
circular in shape.
The stopper 1 is made of a fire-resistant material and
has a funnel-shaped compression plate 2 on the side
towards the interior of the converter, this plate having
an extended funnel channel 5 which leads through the
stopper 1. In the embodiment illustrated the fire-resis-
tant material of the stopper is composed of the following:
alumosilicate, insulating 35~ by weight
2o bonding clay 35~ by weight
water 20~ by weight
mineral oil 6.5~ by weight
plasticizer 0.2~ by weight
liquifier 0.3~ by weight
temporary binders 0.5~ by weight
permanent binders 2.5~ by weight.
2Q~2~3~
Silicates were used as permanent binders, cellulose
materials as temporary binders, polyelectrolytical alco-
hols and fatty acids as plasticizers and liquifiers. The
specific gravity of the stopper is 0.8 - 0.9 Kg/dm3.
Fig. 2 illustrates how the stopper is inserted into
the tapping channel with the help of the setting device.
The base plate 4 of the setting device, which conforms to
the diameter of the tapping channel, is adjacent to the
opposite side 7 of the compression plate.
A pulling claw 6 is introduced through the funnel
channel 5 to a position above the funnel and holds the
stopper for the time being until it is finally positioned
in the tapping channel. The stopper is introduced so far
into the tapping channel with the help of the setting
device that its compression plate surface almost aligns
flush with the interior side of the converter 9. The lever
system of the setting device is used to draw the pulling
claw 6 to the compression plate 2, producing pressure on
the stopper material 1, which deforms until the diameter
of the tapping hole 10 is completely filled in. Fig. 3
illustrates a compressed stopper 8 in the tapping channel
10. With the help of the setting device the thickness of
the stopper base 12 in Fig. 3 is always adhered to for
every tapping channel diameter of a converter, so that it
is guaranteed that the behaviour of the opening is repro-
ducible. Stopper material not required to f ill in the
tapping channel diameter is compressed to the tapping
channel wall with the help of the compression plate as
shown in Fig. 3.
20~~~~~
g
On account of the high radiant heat on the interior
side of the converter, the compression plate melts and
sinters with the f ire-proof material to a solid cap 11,
Fig 3. This cap bears the blast pressure and the resulting
vibration and shaking. The remaining fire-proof insulating
material solidifies to such an extent that it remains
stable in the tapping channel. It does not sinter with the
wall of the tapping channel. The sintered cap is so stable
that it directs the flush slag reliably over the tapping
hole when the converter is tipped and only collapses under
the ferrostatic pressure. The remaining stopper material
is removed within a few seconds by the outflowing steel.
On account of the low material quantities, only a few
foreign substances reach the tapping ladle. The inventive
embodiment and application guarantee a high degree of
reliability in the functioning of the flush stopper, even
where it is exposed to heat for periods longer than two
hours. Where stationary slag measurements were carried out
in tapping ladles of 100 - 250 t capacity, significant
quantities of flush slag could no longer be detected in
200 test relinings.
