The present invention relates to novel slide gate plates with usable dual
surface and novel nozzles compatible therewith for slide gate
assembly. More particularly this invention pertains to novel slide gate
plates which can be put to use just by reversing or turning over so that
this may be utilised for a longer period of time with consequent saving
on expenses. Along with the usable dual surface plates this invention
also envisages production of nozzles which are compatible with novel
slide gate plates ensuring improved performance and less possibility of
damage in the course of handling immensely hot metals or alloys in
liquefied state by means of slide gate mechanisms.
Slide gate refractories play an important role during continuous casting
of molten steel or other non-ferrous metals/alloys from ladle to tundish
and/or tundish to mould. During the casting operation sliding surface of
the plate gets damaged on account of one or more of the reasons given
below;
(i) abrasion between plates in the course of sliding action results in
surface erosion/channel formation;
(ii) surface oxidation due to infiltration/seepage of air between plates
in the wake of sliding action of the plates;
(iii) high bore erosion;,
(iv) erosion of plate/bore during oxygen lancing.
A number of foreign Patents have been granted in the above field, some
of which are given hereinbelow:

1. United States Patent US 5100034 A - 31 Mar 1992 narrates an molten
metal slide gate molten valve. An invention to provide apparatus that
will greatly reduce the amount of aluminum oxides found in the
molten steel as it is poured from a ladle into a tundish or into a
continuous casting machine. The invention says a molten metal
orifice and an open shallow groove in at least one face of the plate
which extends around the entire periphery of the orifice and having
porous refractory means in the base of the groove for introducing a
uniform flow of nonoxidizing gas into the groove.
2. United States Patent 3.581.948 - June 1. 1971 on sliding gate of a
casting ladle for pouring liquid metal, particularly steel, composed of
a fireproof plate provided with an aperture to be firmly set under the
bottom of the ladle by means of a metal frame piece, and a further
refractory shutter plate provided with an outlet, set on a metal
sliding piece which slides on the first plate and is slidably set in the
rigid frame piece. A sliding shutter is provided with an installation
which will allow the prevention and/or the elimination of the
solidification of the melt in the discharge canal of the casting ladle,
particularly in the aperture of the firmly set plate of the sliding
shutter.
3. United States Patent 8.986.813 - March 24. 2015 on sliding plates
invention provides an SN plate capable of being formed in a large
size while using a highly corrosion resistant and highly thermally
expansible refractory product. In the SN plate of the present
invention, a specific refractory material having a thermal expansion
rate as measured at 1500°C. of 1.15 to 2.50% due to addition of
aluminum for improving corrosion resistance is arranged as a part of
the SN plate to cover at least a practically critical region of the SN

plate. A thickness of the specific refractory member is set in a range
of 15 to 25 mm. A portion of the SN plate other than the specific
refractory material is made up of an unburned or burned refractory
product consisting primarily of an alumina-carbon composite.
4. United States Patent US 5403794 A - 4 Apr 1995 says on Alumina-
zirconia refractory material and articles made therefrom. A
refractory article such as a slide gate plate, well block nozzle or like
refractory component used in continuous casting of chemically
aggressive grades of steel is made from a mixture containing about
50-85 wt. % alumina; about 5-30 wt. % alumina-zirconia fused grain;
about 3-10 wt. % zirconia; and about 3-10 wt. % silica, plus an
effective amount of binder materials to permit extrusion, pressing or
like forming process. The pressed shape is fired in an air
atmosphere at temperatures in excess of 1000° C. to form an oxide
bond. The composition of the fired material comprises about 60-90
wt. % alumina; about 5-30 wt. % zirconia; and about 3-10 wt. % silica.
The fired article exhibits excellent hot strength and is resistant to
thermal shock and resistant to the erosive and corrosive effects of
molten steel, including aggressive, high manganese and calcium
treated grades.
5. United States Patent US 5250479 A - 5 Oct 1993 narrates one
Magnesia-carbon refractory composition for slide gate plates and ,
method of manufacture .The invention concerns a fired magnesia-
carbon shape having a combination of properties making it
especially suitable for slide gate plates, inserts for such plates and
for pouring nozzles useful in casting aggressive steels. The fired
refractory shape is formed from a batch consisting essentially of, by
weight 2 to 8% finely divided graphite (natural or synthetic),3 to 8 %

aluminum metal powder,1 to 5% of finely divided silica and/or a
silicon yielding powder, an effective amount of carbon bond forming
resins, and the balance coarse and fine magnesia grains. The
magnesia grains contain less than about 0.02 weight percent boron
oxide. After firing, the shape is characterized by a carbon bonding
system including spinel (magnesia-alumina) phase plus aluminum
carbide bonding the magnesia-carbon matrix. The refractory shape
is preferably carbon impregnated after firing to further enhance its
properties.
6. Patent No. WO 1999047472 A1 - Sep 23.1999 on low silica refractory
slide gate plate, nozzle, or similar refractory component for use in
the continuous casting of steel is disclosed which comprises about
50-90 wt.% particulate alumina, about 5-28 wt.% alumina-zirconia
fused grain, about 3-10 wt.% zirconia, and less than about 2.5 wt.%
silica. Firing at temperatures in excess of 1370 °C produces an
oxygen-bonded article with excellent resistance to thermal shock.
The fired article also resists corrosion and erosion by molten steel,
including high manganese and calcium grades of steel.
7. United States Patent US 5670075A - Sep 23. 1997 describes one
sealing gas delivery system for sliding joints in the continuous
casting of steel, gas is prevented or inhibited from contacting molten
steel through the valve slide plate by feeding inert gas through
channels in the slide plate and adjacent parts; the channels contain
porous refractory inserts and can be connected to outside sources
through juxtaposed side channels
Conventionally the assembly uses two different plates and nozzles
compatible therewith. The top plate remains stationary and bottom

plate slides during use. Flow of molten steel/non-ferrous metal or alloy
from ladle to tundish or from tundish to mould is normally controlled by
the bottom plate. In the course of casting operations, the plates suffer
wear and tear in different stages due mainly to oxidation, corrosion,
and abrasion, which eventually results in termination of life of the plate
with the formation of channels on the slide plates. On account of such
channel formation, there is formation of thin metal film between the
plates which render them unfit for further use. Current practice is to
employ top and bottom plates which are worked only on single side, the
other sides of the plates are fixed/clad with steel CAN/cassettes and
mortar. Moreover, life of the plates is directly related to and dependent
on the life of the collector nozzle. Once life of the plate is over, collector
nozzle(s) also can no longer be of use despite being in perfectly good
condition. Such a situation results in loss of materials and consequent
cost-effectiveness.
It is to be kept in mind that operation of slide gate plate is critical as no
preheating is possible or available prior to the said plate being put to
use.
Hot metal passes through the bore or orifice which is located at the
centre or central region of the plate. Depending on the heat gradient
from bore to periphery, thermo-mechanical stress tends to develop in
the plate configuration.
In conventional slide plates, steel plates are anchored with steel
cassettes which cause hindrance in releasing stresses resulting in
multiple cracks in refractory.

The present invention also encompasses within its scope a novel
means to avoid full steel cassetting to overcome the stress and
consequently it improves the life of the refractory by providing a band
all around the periphery of the refractory body. Material of construction
of such band may be selected from, inter, alia, metal, alloy, ceramic or
metallo-ceramic bodies and such band may optionally be equipped with
clamps located at predetermined positions to securely hold the band in
place, eliminating possibility of even slight displacement in the course
of operation of the slide gate during passage of hot metal/alloy through
the orifice/hole of the plates and nozzles from ladle to tundish or from
tundish to mould.
The principal object of this invention is to enhance the working life of
slide plates, production procedure and consequent improvement in
economic viability.
A still further object of this invention is to provide novel slide gate
plates wherein the said plates are designed for use of both the sides so
that when working surface erodes, the opposite non-worked surface is
reversed and used as an effective working surface.
Another object of this invention is to provide novel slide gate plates
wherein the slide plates are provided with metal, ceramic or metal-
ceramic bands all around the periphery of the refractory body,
optionally equipped with clamps at predetermined positions, for
overcoming stress and also to prevent any possibility of displacement
of the refractory body in the course of operation of the slide gates to
control the flow of hot metal or alloy.

Yet another object of this invention is to provide collector nozzle, fixed
nozzle and/or outer nozzle which are compatible with the aforesaid
novel slide gate plates ensuring smooth functioning thereof.
The foregoing objects are fulfilled by the present invention which
relates to novel slide gate plates and nozzles compatible therewith,
characterized in that the said plates have usable dual surfaces,
wherein when working surface thereof erodes, the opposite non-
worked surface is reversed and used as an effective working surface
and is associated with nozzles of unique design which are compatible
with said plates.
The aforementioned plates may be made from a solid block of
refractory material having a monolithic structure or may be a sandwich
structure formed from a plurality of ceramic or refractory bodies
bonded by a suitable heat-resistant adhesive.
The refractory sliding plates with dual working surfaces are equipped
with metallic, ceramic or metallo-ceramic band all along the periphery
thereof, optionally carrying metallic or metallo-ceramic clamps at
predetermined positions.
For steel casting, such bands are made of steel and are used for fixing
the sliding plates, particularly to prevent displacement or loss of
alignment of said plate(s), and also to avoid development of any stress.
Slide gate plates of this invention are formed from refractories selected
from raw materials, inter alia, alumina, alumina-silicates, magnesia,
zirconia, Mag. Al. spinel, carbon, zirconia-mullite, spinel, fused/dead
burnt/sintered magnesite, zircon and its composites, clay, graphite,

metallic carbides, nitrides, oxides, oxynitrides, with additives,
metallic/non-metallic antioxidants and organic resin/pitch/tar as binder.
These raw materials are subjected to mixing in high speed mixer
machine. The green mixes are cured at a temperature not exceeding
50°C, preferably at around 25°C, and pressed in hydraulic/mechanical
press to impart desired shapes. The pressed items are dried by firing at
temperatures exceeding 50°C. Following drying the shaped articles are
heated in a kiln/furnace at temperatures exceeding 500°C, preferably at
1000°C, in a reducing atmosphere. Fired collector nozzles are
cassetted with steel casing by cement-bonded mortar. Fixed nozzles
are not cassetted, whereas fired slide plates are fixed/fitted with steel/
metallic/ceramic/metallo-ceramic bands which are ground/ polished to
impart a smooth surface in the final product. These bands have been
developed with a view to replace steel cassettes conventionally used to
minimise generation of thermo-mechanical stresses during operation.
The bands aforesaid are usually made of steel or metal or metallo-
ceramic bodies capable of withstanding a temperature in the vicinity of
around 1700°C. Such bands of desired size are preheated in a furnace
at a temperature varying between 500°C and 1000°C, preferably at
800°C, for 10-15 minutes. Slide plates with cleaned surface are placed
on a flat surface. Steel band turning red hot in the furnace is removed
therefrom and set on the edges of the slide plates held on a jig, followed
by manually slow hammering or by mechanical means on the band put
on the jig to seat properly on the periphery thereof, both from the
length and width sides, for better clamping and hold. The band gets
tightened and exerts compressive force on the refractory body once
the steel/metal/ metallo-ceramic band cools down to ambient
temperature. It has been observed that thermal expansion of steel band
for mild steel after heating was 0,5% in length and width.

As pointed out earlier, the upper plate remains static and the lower
plate is made to execute a sliding action in order to control the flow of
hot, liquid metal from ladle to tundish or from tundish to mould, where
casting is carried out. Such sliding action is conducted and controlled
by employing mechanical, pneumatic means, or more recently sensors
are being deployed for this purpose.
The refractory body of the sliding plates may have varying shape, size
and dimension; however, all of them carry a suitably located orifice or
hole through which passes the liquefied metal or alloy, the latter for
non-ferrous casting. The hole diameter varies between 10 mm and 150
mm, preferably between 30 mm and 60 mm. But the bore diameter may
undergo upward variation while employing plates of higher dimensions.
The present invention also encompasses within its scope nozzles of
unique design which are compatible with the slide gate plates of this
invention, which renders the slide gate assembly simplified and more
functionally effective eliminating the drawbacks inherent in the
conventional assembly, which would be manifested from the
accompanying drawings, wherein -
Figs. 1a, 1b, 1c show conventional slide gate refractory plates and
nozzles compatible therewith,
Figs. 2a, 2b, 2c depict novel slide gate refractories and nozzles
compatible therewith,
Fig. 3 gives a side view of the slide gate assembly of this
invention,

Fig. 4 shows a cross-sectional view of the novel slide gate
assembly,
Fig. 5a illustrates a horizontal position of slide gate
mechanism fitted at the bottom of the ladle in a
ready for operation condition,
Fig. 5b demonstrates the vertical position of the slide gate
mechanism fitted in the ladle bottom, ready for
application.
In the foregoing Fig. 1a, Fig. 1b and Fig. 1c there is shown conventional
slide plate, collector nozzle and fixed nozzle, respectively.
In Fig. 2a, Fig. 2b and Fig. 2c there are illustrated slide plate, collector
nozzle and fixed nozzle of improved design in accordance with this
invention.
Referring to Fig. 3, 3a is ladle well block, 3b is the adaptor plate and 3c
is the mounting plate.
From a comparison of Figs. 1 and 2 one may easily ascertain the
difference between the conventional and novel nozzles and sliding
plates of this invention. The conventional sliding plate is usable on one
side only, whereas plates of this invention can be used on both sides,
merely by turning over. The former has a metal cassette but the latter is
equipped with a band all along the periphery, which may optionally
carry clamps located at predetermined positions to ensure a firm grip.

The overall assembly has also undergone simplification, as would be
apparent from the comparison of Fig. 3 and Fig. 4, which ensures
trouble-free operation over a longer period of time.
The present invention offers quite a few advantages, as may be outlined
below:
(1) Use of both sides of slide plates enhances cost effectiveness and
ensures preservation and saving of natural resources.
(2) Ease of dismantling of refractory body from steel band after use
as there is no mortar/adhesive used between band and refractory
body.
(3) Escalated life of the dual working surface sliding plate has been
found to exceed 1.5 times in comparison to conventional plates.
(4) Increased pay load during firing reduces firing cost by achieving
fuel saving.
(5) As there is no spigot in plates and any groove in nozzles, the
novel assembly ensures better consistency and accuracy in
dimension of the cast products.
Additional modifications and improvements of the present invention
may also be apparent to those skilled in the art. Thus, the particular
combination of parts described and illustrated herein is intended to
represent only one embodiment of the present invention, and is not

intended to serve as limitations of alternative devices and features
within the spirit and scope of the invention.
Having described the invention in detail with particular reference to the
illustrative examples given above, it will now be more specifically
defined by means of claims appended hereafter.

We claim:
1. Novel slide gate plates with usable dual surface and nozzles
compatible therewith for slide gate assembly, characterised in that
both the surfaces of the said plates can be put to use, when working
surface thereof erodes, the reverse non-worked surface may be
turned over and utilised as an effective working surface, and is
associated with nozzles of unique design which are compatible with
said plates forming slide gate assembly.
2. Novel slide gate plates and nozzles compatible therewith as claimed
in Claim 1, characterised in that the said plates may be made from a
solid block of refractory material having a monolithic structure or
may be of sandwich structure formed from a plurality of ceramic or
refractory bodies bonded by a suitable heat resistant adhesive.
3. Novel slide gate plates and nozzles compatible therewith as claimed
in Claims 1 and 2, characterised in that raw material for the
refractory block is selected from, inter alia, alumina, alumino-
silicates, Mag-AI-Spinel, carbon, zirconia-mullite, spinel, fused/dead
burnt/sintered magnesite, zircon and its composites, clay, graphite;
and metallic carbides, nitrides, oxides or oxynitrides, with additives,
metallic/non-metallic anti-oxidants and employs organic
resins/pitch/tar as binders.
4. Novel slide gate plates and nozzles compatible therewith as claimed
in Claim 3, characterised in that the said raw materials are subjected
to proper mixing in a mechanical mixer, preferably in high speed
mixing machine, and green mixes thus obtained are cured at a
temperature not exceeding 50ºC,preferably 25°C, and pressed in

hydraulic/mechanical press to impart desired shapes, followed by
heating at above 50°C to achieve drying, and thereafter the dried
shapes are fired in kiln/ furnace at temperatures above 500°C,
preferably at 1000°C in reducing atmosphere to produce the desired
product, whereas fired collector and fixed nozzles are cassetted by
employing cement bounded mortar.
5. Novel slide gate plates and nozzles compatible therewith as claimed
in Claims 1 to 4, characterised in that the slide plates are equipped
with metallic, ceramic or metallo-ceramic band, usually a steel band,
all along the periphery thereof, optionally carrying metallic or
metallo-ceramic clamps at predetermined positions, for firmly
holding the said plate(s), particularly to prevent displacement or loss
of alignment of the said plate(s) and also to avoid development of
any stress.
6. Novel slide gate plates and nozzies compatible therewith as claimed
in any of the preceding Claims, characterised in that the said band is
subjected to grinding and/or polishing prior to being fixed along the
periphery of the ceramic/refractory plate(s).