Tap spout for metallurgical vessels and method of repairing

A tap spout, particularly for allowing molten metal to be discharged from oxygen-steel converters, includes a replaceable unit including a tubular wear lining and a jointing layer secured thereto. An inner lining of the tap spout may thus be repaired with relatively simple maintenance work by removing the inner lining and subsequently inserting the replaceable unit into an outer lining of the tap spout to form a new inner lining of the tap spout. The replaceable unit is adapted to facilitate either a press fit, and in particular, a fit ensured by axial compression of the jointing layer, or an expansion fit with the outer lining to secure the replaceable unit therein.

BACKGROUND OF THE INVENTION 
The invention relates to a tap spout for metallurgical vessels, 
particularly for oxygen-steel converters which may be tilted about a 
rotary axis, comprising a refractory permanent lining incorporated in the 
refractory brickwork of the vessel and a refractory, replaceable, tubular 
wear lining mounted therein by means of a refractory jointing layer. 
During a period of delivery from metallurgical vessels, particularly a 
converter run, it is essentially attempted for reasons of efficiency to 
maintain the maintenance expense on the converter as small as possible. 
The converter tap spout requires regular maintenance, principally in order 
to ensure a dense poured stream during the tapping period and in order to 
avoid slag from also flowing out of the converter if a significant crater 
should form at the inlet end of the tap spout. This requires a tap spout 
which is always intact, which can only be permitted to become worn within 
certain limits and which thus must be renewed within the life of the 
converter many times as part of a hot blast repair. 
AT-A-326164 discloses a metallurgical vessel with a tap spout which has 
perforated blocks which are firmly inserted into the vessel brickwork 
behind one another as a permanent lining and in whose bore there are 
mounted wear tubes serving as a wear lining. These wear tubes are fixed in 
position by the pouring or the ramming of a refractory composition into 
the gap between the wear tubes and the permanent lining. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide an improved tap spout 
which requires relatively simple maintenance as compared to prior art tap 
spouts. 
To achieve this object, the tubular wear lining and the jointing layer 
surrounding it are a replaceable unit which may be inserted into the 
permanent lining. Such a preassembled replaceable unit may be easily and 
rapidly positioned in the passage in the permanent lining, which has been 
cleaned of wear residues, with comparatively little labor-intensive 
expense so that a lengthy, separate application of, for instance, a 
spraying, pouring or stamping composition, for fixing the wear lining in 
position is unnecessary. 
A jointing layer, which is radially compressed after the insertion of the 
replaceable unit, can conveniently be provided in the permanent lining of 
the tap spout. The jointing layer may be applied to the wear lining with 
an outer tolerance with respect to the permanent lining which renders a 
simple press-fit of the replaceable unit in the tap spout, and in 
particular, the tolerance can ensure an operationally reliable fit of the 
replacement unit in the permanent lining upon a secondary axial 
compression of the jointing layer. Alternatively, a jointing layer may 
also advantageously be used which comprises refractory material which 
expands under the action of heat so that a tolerance of the jointing layer 
with respect to the permanent lining, which is present before the 
insertion of the replaceable unit, is taken up under increasing 
operational temperature and a sealed, firm fit of the replaceable unit is 
automatically achieved. Both jointing layers can, for instance, be brushed 
or otherwise spread onto the wear lining in the form of a refractory 
composition or wound onto a strip of paper so as to adhere to it. A 
composition mixed with a blowing agent serves as the expanding material. 
It is in all cases advantageous to provide the jointing layer with gas 
passages extending in the longitudinal direction of the replaceable unit 
in order to allow gas to flow therethrough and force back slag in the flow 
region of the tap spout. Such gas passages can be easily produced, for 
instance, by inserting into the jointing layer cords which can be burnt 
away. 
It is also an object of the invention to provide the jointing layer on a 
wear lining which is unitarily constructed as a tube so as to realize a 
simple and thus easily fabricatable replaceable unit. The replaceable unit 
further advantageously has, at least at its inner end, a wear lining 
section with a restricted, for instance, square-shaped, cross section. The 
molten metal thus flows through the tap spout relatively smoothly without 
intensified eddy formation which in turn prevents a crater from being 
prematurely formed by erosion at the inlet of the tap spout and thereby 
obviates the undesirable outflow of slag together with the molten metal 
which is known to occur when such a crater is in fact formed. Finally, to 
increase the service life, in accordance with the invention, the tap spout 
may be provided with a replaceable outlet spout at the outer end of the 
replaceable unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The converter, whose tap spout region is shown, has a sheet metal shell 1 
and a refractory lining comprising brickwork 2 which becomes worn and a 
backing 3. The tap spout 4 is fixed in position within a sleeve 5 of the 
sheet metal shell which terminates at an external connecting flange 6. The 
core of the tap spout 4 is a refractory fitting comprising an outer 
permanent lining 7, a jointing layer 8 and a tubular inner wear lining 9 
which surrounds the tap hole 10. When the converter is relined, the 
fitting 7 to 10 is inserted preassembled into the lining 2, 3, coaxially 
with the sleeve 5 and is there embedded in a refractory lining 11. 
The permanent lining 7, which comprises a plurality of safety blocks 7a, 
affords a reliable connection with the converter brickwork 2 and remains a 
component of the refractory linings 2, 3 and 11 until the next relining of 
the converter. On the other hand, when the wear lining 9 is in a state of 
advanced wear down to the jointing layer 8 and when the tap spout inlet is 
eroded into a crater shape (indicated in chain lines in FIG. 5) repairs to 
such locations are basically repeated as necessary. This involves 
so-called hot repairs which are to be effected as rapidly as possible with 
the converter in an uncooled state. Firstly, remaining fragments of the 
jointing layer 8 and the wear lining 9 are cleared away, for instance 
drilled or forced out from the exterior, so that, as may be best be seen 
in FIG. 5, the round passage 7b in the permanent lining 7 is exposed. 
Then, if it is worn into a crater shape, the inner safety block 7c (FIG. 
1) is replaced by an annular replacement safety block 7d fixed in position 
with a refractory composition 12 (FIG. 5). On the other hand, the safety 
block 7c can remain in position if visual judgement suggests that its 
durability is such that it can withstand the time interval until the next 
repair. 
After these preparations, the replacement of the wear lining 9 is effected 
by inserting a prepared replaceable unit, comprising jointing layer 8 and 
wear lining 9 and also a jacket 13, in the round passage 7b in the 
permanent lining 7 with a single operation, preferably with the aid of a 
handling tool 14 operated by a lifting appliance. As shown in FIGS. 3 and 
4, the wear lining 9 of the replaceable unit 8, 9, 13 comprises wear tubes 
9a forming a row in which the tubes 9a are aligned by tongue and groove 
connections, or a unitary wear tube (FIG. 5) and is surrounded by a 
moldable jointing layer 8. The jointing layer 8 is retained by a jacket 13 
in such a manner that the unit 8, 9, 13 is press-fit without difficulty 
into the permanent lining 7 and, in particular, the unit 8, 9, 13 can be 
fixed in position in the permanent layer by facilitating a secondary axial 
compression of the jointing layer 8. On the other hand, the jointing layer 
8 can comprise a compound or mortar material, for example 
vermiculite-containing materials and inflated graphite, which expands or 
swells under the action of heat and which ensures a firm expansion fit of 
the replaceable unit 8, 9, 13 at the operational temperature of the 
converter. After installation of the replaceable unit 8, 9, 13, any crater 
still present around the replaceable unit 8, 9, 13 in the inner surface of 
the brickwork 2 and in the permanent lining 2 is filled with a hot repair 
compound. When using wear tubes 9a assembled in a row these are 
conveniently held clamped under stress on the handling tool 14 during 
their handling. 
In a modification of the round cross section of the passage of the wear 
tubes 9a, the inlet wear tube 9b can have a diamond-shaped cross section, 
a slit-shaped cross section or other restricted flow cross section 9c 
which inhibits the formation of eddies in the molten metal flowing into 
the tap hole 10 to prevent the crater-shaped erosion of the hole inlet. A 
similar preventive effect against premature erosion at the end of the tap 
hole 10 by molten metal flowing out when the converter is tilted is 
achieved by the replaceable outlet spout 15 which is replaceably secured 
to a removable connecting plate 16 of the connecting flange 6 and, if 
necessary, can be replaced by a blind plug. 
In a further embodiment of the replaceable unit 8, 9, 13, the jointing 
layer 8 has gas passages 17 (FIG. 4) extending parallel to the tap hole 
10, through which, if necessary, gas is supplied to the molten metal inlet 
end in order to blow away any slag flowing with the molten metal. If the 
jointing layer is, for instance, brushed or otherwise spread on, it is 
advisable to retain it in position on the wear lining with the jacket 13. 
A flexible jacket, which can have perforations and/or reinforcements, 
should particularly be used. 
The invention has been described above with respect to preferred 
embodiments thereof. However, various changes and modifications will 
become apparent to those of ordinary skill in the art. Such changes and 
modifications are seen to fall within the true scope of the invention as 
defined by the appended claims.