CA1138645A - Refractory structure - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A method of conditioning a refractory structure for use with molten metal having a duct for working fluid which comprises passing working fluid through the said duct.

Description

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The invention relates to refractory bodies and finds particular use as wear:Lng parts for use in the outlets of metallurgical vecse]s such as casting ladles and tundishes and as refractory structures for use in outlet control devices 5. for such vessels and in particular slidin~ gate noz21e apparatus.
The invention is described with particular reference to the casting of steel but, the refractory wearing parts according to the invention are also applicable to the casting of other metals which cause considerable wear because of their high 10. melting point or their corrosive nature.
Such apparatus comprises a stationary refractory upper plate defining a discharge passage and adapted to be located on the outside of the vessel in Juxtaposition to the outlet orifice of the vessel, e.g. by being held in a metal frame attached to 15. the shell of the vessel, and a movable refractory sliding plate defining a discharge pa~sage and rnounted for movement between an open position inwhich the discharge passages of the two plates are in register and a closed position ~n which -the movable plate shuts off the discharge passage of the fixed plate.
20. Movement of the movable plate can be rotatory though a straight sliding motion is preferred.
One form of such apparatus h~s a fixed upper pla-te and a movable lower plate. Such apparatus will be referred to herein as a two plate sliding gate nozzle apparatus. The mo~able plate 25. is preferably mounted for movement in a metal casing, and may incorporate an outlet nozzle or- cooperate with one which is also movably mounted in the me~al casing.
Anothèr form of such apparatus has the movahle plate mounted for movement bet~een upper and lo~er fixed plates and 30. is thus subs-tantially parallel faced and the lol;er fixed pla-te KDNK/JP 2.

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incorporates or cooperates with an outlet nozzle. Such apparatus will be referred to as a three plate sliding gate nozzle apparatus.
Conventional refractory plates and nozzles for use in 5. such apparatus are made by pressing a refractory granular mass and then firing it at high ternperature and then drilling out the outle-t passage.
Refractory wearing parts of the described kind are exposed in use to wi~ely varying therrr!al stresses. On the 10. one hand such refractory wearing parts are exposed during the pour to very high temperatures at which me-tals have a maJor corrosive and erosive action on refractory materials. On the other hand such refractory wearing parts are exposed at the start of the pour to an unusually severe and sudden thermal 15. shock which gi~es rise to correspondingly high mechanical stresses due to differential thermal expansion. For both these reasons the service life of known refractory wearing parts of the kind contemplated is short~ For example, on average a sliding plate requires replacement after only two 20. pours, representing, for example, a total casting time of only two hours.
According to the present invention a refractory structure which may be used as a fixed or sliding plate for a sliding gate nozzie or as a sleeve or nozzle brick for the outlet from 25. a metallurgical vessel comprises A) a body of cast refractory concrete rnaterial defining at least one discharge passage - passing through the body and B) at least one reinforcing element, preferably metallic, located within the body or forming a face or faces thereof and interlocked mechanically with the refractory 3(). concrete with which it is in intimate contact o~er the whole of any of its surface which is juxtaposed to the refractory concrete KDI~K/JP 3.

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1~L3E~5 or C) means defining at least one duct for a work-ing fluid intle body or D) the discharge passage being defined by an insert of material embedded in the refractory concrete and having bettelr wear resistance than the refractory concrete, 5. or A), B) and C), or A), B) or C) ana D) or A), B)y C) and D).
The metallic reinforcing element is referred to as being interlocked mechanically with the refrac-tory concrete.
It is to be understood that this means not only arrangernents in which the interlock is such that the cast refractory concrete 10. body and the reinforcing element car~ot be separated withou-t breaking one or other of these components, but also arrangements in which the interlock is at least operative in the situation in which the plate is actually used so as to resist separation o~ the cornponents at least so far as shear forces in the principal 15. plane of the plate are concerned.
Thus when the structure is in the form o~ a plate in a sliding gate nozzle it is held in compression in use, both a-t its edges and at i-ts opposed pr:incipal faces. It i~1 thus only essential that the mechanical interlock is sufficient to reslst 20. separation of the cast concrete body from -the reinforcing elern2nt in a direction parallel to the principal plane of the plate.
However arrangements in which the components are inseparab:Ly attached to each other are preferred.
An object of the first aspect of the present invention 25. is to provide refractory wearing parts of t~le kind conternplated in such a way that their service life is extended. The invenliQ1l achieves this object by making the refractory part of a refrac-tory concrete and by forming at least one duct in the refraetory concrete for the c~rculation therethrougil Q~ a workin~ r~1ediur 30. such as a heating or cooling fluid.

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In a first aspect of the invention~ a refractory wearing part is provided with one or more duc-ts or a system of ducts formed and distr'ibuted as desired in the wearing part so as to permit the introduction of a heating or cooling 5. fluid into the interior of the part, where the occurrence of temperature shock or of undesirably high temperatures in the material of the refractory part may ~e avoided or reduced.
By appropriately controlling the supply of heating and cooling fluid it is po'ssible for example to raise the ternperature of 10. the refractory wearing part prior to the start of a pour sufficiently to obviate the material being damaged by the temperature shock at the start of the pour. During the pour the ,temperature peaks which othe~ise arise in the wall of the passage may be rèduced to an acceptable level by introducing 15. a coolant for a suitable period of time. In this way, on the one hand, temperature changes can be made to proceed gradually and, on the other hand, the temperature peaks to which the refractory part is exposed can be limited to a level at which the ' ' service life of the part will be increased.
20. In a preferred form of the invention the refractory structure is in the form of a plate, the discharge passage being transverse to the major plane of ~the plate and the ducts being at least partially and preferably substantially parallel to the principal plane of the plate. Preferably the ratio of the maximum longi-25. tudinal dimension of the sliding surface of the plate to the minimum thickness of the plate is in the range of ratios of 25:1 to 7.5:1 and more preferably 20:1 to 10:1 and especially 15:1 to 10:1.
In a preferred form of the invention the duc-ts are 30. tortuous. The term "tortuous duct" covers any duct which undergoes KDNK/JP 5.

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~i31~6~5 a change of direction in its passage from its co~mencement at an inlet aperture to the body to its emer~ence at an outlet aperture to the body. These ducts may have a circular or non-circular cross section, such as a rectangular, 5. oval or other cross ~ec-tion. Parts of the ducts may be curved, others straigh-t and they rnay intercommunicate at an angle, for instance at a right angle. The ducts may be formed by metal or ceramic or other heat resistant tubes incorporated in the refractory wearing parts. Preferably at least the 10. entry to a duct is formed by a metal insert to facilitate connection of the ducts to a supply of working fluid.
In ano~her embodiment of the invention the refractory wearing part is of two-part construction, preferably being divided in a parting plane parallel to its principal plane 15. and one of the components of the piate contains the duct or ducts with one open side in such a way that when combined with the other plate component or cover the open side of the duct or ducts is closed.
The cover is preferably flush with the surface of the 20. plate which may have parallel principal surfaces. Preferably the inner edge of the cover is spaced away from the edges of the dischar~e opening. It may consist of refractory material, e.g. a ceramic or of steel.
The openings of the duct or ducts may be in the cover.
25. Alternatively the inlet and outlet openings may be formed in the sides or ends of the plate. It is desirable that at least the inlet opening of the ducts should be formed by a metal insert to facilitate connecting the duct to a gas or liquid supply.
30. Refractory wearing parts according to the invention may KD~/JP 6.

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be produced by pouring a refractory co~crete into an appropriate mould, means determining the duct or ducts of desired cross section being disposed in the desired position inside the mould before t~e concrete is poured.
5. The means used fcr forming the duct or ducts may, if this is desirable, be of a temporary nature, for instance they may consist of a combustible material such as paper or synthetic plastics material, so that they can be remo~ed by heating before the refractory wearing part is used for the first time, or may 10. be such that their removal during first use will not result in a restriction of the duct cross sec-tion. Alterna-tively the rneans may also consist of a removable solid material that possesses the desired shape of the duct and that is inserted in the mould (as a core) and removed after the refractory part has been 15. moulded, for instance they may consist of a combustihle material such as paper or synthetic plastics Inaterial, so that they can be removed by heating before the refrQctory wearing part is used for the first time, or may be such that their removal during first use will not result in a restriction 20. of the duct cross section. Alternatively the means may also consist of a removable solid material that possesses the desired shape of the duct and that is inserted in the mould (as a core) and removed after the refractory part has been moulded, for instance by the application of heat, for instance by making ~5. such a core of a low melting alloy, such as a tin alloy or Rose's metal. This has the advantage of permitting ducts of non-circular cross section to be easily produced. Alternati~rely the duct or ducts may be formed of heat resistant ~etal or ceramic tubes or pipes.
30. Preferably tne duc-ts are so shaped that they embrace KDI~K/JP 7.

113~6~5 the discharge passage traversing the slidin~ plate by surrounding the same in 'at least 180 arc and preferably in a 360 circle. In plates having asymmetrically disposed discharge passages the ducts ~lill with advantage run at 5. least from the middle, preferably from the remote end of the plate in an at least 180 arc around the discharge passage and then preferably extend back again at least to the middle and preferably to the same end of the plate.
The inlet openings into ducts surrounding the discharge 10. passage are preferably tangentially disposed to the circle to facilitate circulation of the working fluid which may be heating or cooling ~luid.
The heating fluid and the cooling fluid are preferably gaseous. With advantage a heating fluid may be a combustlon 15. gas, whereas the coolant may with advantage be compressed air.
The invention also extends to a method of conditioning, particularly sliding plates in sliding gate nozzles for vessels containing molten metal, which is characterised in that heating fluids and/or cooling fluids are circulated through at least 20. one duct contained in the sliding plate.

The invention also relates to refractory structures containing a gas-permeable insert and adapted for use in or with 25. a vessel which is itself adapted to con-tain molten metal, parti~
cularly for discharge control means on vessels adapted to contain a metal melt.
Refract~ry structures lncorporating gas-permeable inserts have been described for example in German Pat. Specn, No. 1935401, 30. German Pat. Specn. No. 2019550, and German as-filed Patent Specn~
No~ 2218155.
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1~3~ L5 The purposes of the gas-permeable inserts include that of permitting major volumes of a gas to be introduced under pressure into the space or cross sectioll provided for the discharge of the metal melt.
5. When such gas-permeable inserts are provided in conventional fired refractory plates or nozzles they must be inserted into pre-bored holes and not inconsiderable difficulties arise, particularly in quantity production, in firmly securing them in their holes and in making suitable 10. arrangements for the supply of the gas.
It is an object of the invention to avoid these draw backs and to provide more simply a refractory component of the kind contemplated above. In the present invertion this object is achieved by embedding the gas-permeable insert in 15. refractory concrete from which the refractory component is formed.
The gas-permeable porous insért is embedded preferably directly, in the body of refractory con~crete, for instance by pouring and vibrating the concrete around the inser-t. Ducts 20. for working fluid communicating with the gas permeable insert may be formed in the in the refractory concrete. ~Iowever, if desired, the insert may be previously located in a metal surround in such a way that a cavity remains between an inner face of the insert and the refractory concrete body9 the gas supply 25. means, for instance a duct moulded into the concrete opening into this cavity. The ducts extends preferably to a remote end face of the component. In the case of a slee~e (nozzle brick) containing a central metal discharge passage or of the fixed plate of a 2-plate sliding gate noz~le, the gas-permeable inser-c 30. may with advantage extend to the wall of the metal discharge KDNK/JP 9.

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passage traversing the part and may encompass the entire periphery of this passage, thus itself forming the wall of this passage.
With a sliding plate for a two-plate sliding gate 5. nozzle (i.e. comprising one fixed and one movable plate~, the gas-permeable insert is preferably located in the sliding plate and flush with the top face of the latter so as to be below the discharge passage of -the fixed plate when the gate is shut. The insert may be adapted to be supplied 10. with gas via a duct extending from one end or side wall of the plate or the bottom face of the plate.
~ en the inlet is in the bottom face of the sliding plate of a three-plate sliding gate (i.e. having two fixed plates and one movable plate in the middle~, access thereto for the 15. gas may be obtained via a duct in the lower fixed plate. This duct is preferably formed in a cast refractory concrete plate as described above.
The use of gas-permeable inserts which are embedded in a refractory component of a 2- or 3-plate sliding gate nozzle 20. made of refractory concrete is of particular importance in preventing the gates from becoming inoperative by the molten metal freezing in the discharge passage above the closed sliding plate. The gas preferably used is an inert gas, such as argon or nitrogen.
25. The form of construc-tion according to the invention in which a ~as-permeable or porous insert is embedded in a refractory part made of refrac-tory concrete 9 for instance by pouring and possibly compacting the concrete, e.g. by vibratlon9 around the insert, provides an oustandingly reliable bond between 30. the gas-permeable insert and the refractory concrete and KDNK/JP 10.

~3~ 5 s~rprisingly there is no significant impairmen-t of the permeability to gas of the gas-permeable or porous insert.
The gas-permeable insert and the ducts for the working fluid may be loca-ted on a metal plate which is flush with 5. the underface of the sliding or middle plate.
The working fluid may be conducted to the gas-permeable insert through an opening in the metal plate ln the bottom of the sliding plate, which opening communicates with a recess in the upper surface of the bottom fixed plate, and the recess 10. may be cor~ected to an external gas supply pipe.
Alternatively the working fluid may be conducted to the gas-permeable insert through an opening in the upper surface of the sliding plate, which opening communicates wit,h a recess in the undersurface of the upper fixed plate, and the 15. recess may be co~nected to an external gas suppiy pipe.
The length of the recess is preferably so calculated and its position so chosen that the closing movement of the sliding plate uncovers the gas admission from the recess to the gas-permeable insert when the insert is~in the working position 20. in the metal discharge passage, and the opening movement of the sliding plate shuts off the gas supply when the gas-permeable insert withdraws from the discharge passage and the latter is opened for the discharge therethrough of molten metal.
The invention also extends to cases where the refractory 25. component is in the form of a sleeve or nozzle brick for lining the well brick of a metallurgical vessel.
The gas-permeable insert may be itself sleeve-shaped and embedded in the middle of the sleeve. The gas-permeable insert preferably inserted into a sleeve shaped sheet metal surround 30. before bein~ embedded, so that a clearance remains bet~reen the outside peripher~ of the insert and the inside surface of the KDN~/JP 11.

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metal surround, which clearance serves as a gas distributing chamber.
The invention also extends to a method of producing a nozzle brick in accordance with the invention in which the 5. concrete pouring mould comprises an outer form and a central core for holding the gas permeable insert in the desired position inside the mould. In a preferred form of the invention a jacket conforming with the shape of -the form and consisting of a fire-resistant felt is introduced into the form before 10. pouring begins, and is then firmly bonded to ~e refractory component O
The gas-permeable insert is preferably soaked with water before the concrete is poured.
As mentioned above the invention relates to sliding gate 15. nozzles for vessels adapted to contain molten metal, parti~
cularly steel casting ladles and -tundishes for the continuous casting of steel.
In such sliding gate nozzles thermal stresses (i.e.
mechanical stresses due to differential thermal expansion) 20. often arise ~or which it is very difficult to compensate.
In addition, high thrusts are encountered. These may jointly give rise to bending and tensile stresses of a severity which the refractory material of the nozzle plates cannot withstand.
The conditions are unlike those when refractory components 25~ and parts are purely statically loaded such as occur in furnace - walls or roofs. There it is fairly easy -to~make allowance for any possib]e thermal stresses and strains. Tensile stresses can be largel-y avoided and dynamic thrus-ts do not arise.
In conven-tioIlal sliding gate nozzles the above mentioIled 30. severe stresses are in practlce absorbed by embedding the KDNK/JP 12.

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refractory material in the metal supporting structures of the gate in a densely compacted layer of mortar which makes all-overlclose surface contact with the refractory plate and the suppo~ting structure. Th~ generally accepted 5. solution of the problem is technically satisfactory, provided it is properly applied. However, it requires skilled manual work and the functional reliability of the gate depends upon this work having been carried out with repeatably uniform precisian. The dependence of ope~atlng safety upon purel~r 10. human factors is a major defect, bearing in mind the freauency with which the wearing material in sliding gates requires replacement and the danger o~ a serious steel leakage. An additional factor is that the service life of the refrac.toy material located by embodiment in mortar is relatively short, 15. particularly in the case of the orificed plates used for controlling such sliding gate nozzles as mentioned above.
It is an object of this aspect of the present invention to provide a sliding gate nozzle for vessels adapted to contain a metal melt, wherein the above described defects are at least 20. redvced in severity.
This aspect of the invention relates to a sliding ga-te nozzle for vessels adapted to contain metal melts comprising at least one fixed and one movable plate, at least one of the plates being associated with a supporting frame and each plate having 25. an orifice for the passage therethrough of the metal melt, characterised in that ~ least the movable sliding plate consists substantially of refractory concrete and on its side facing away from i-ts slidin~ face is provided with a metal reinforcement embedded therein wi-thout the use of mortar, said reinforce.rnent 30. being thus anchored in the sliding plate so that tension, KDNK/JP 13.

1~3~5 compression or shear forces cannot shlf-t it, the sliding plate itself being located in -the supporting frame without the use of mortar and the likewise movable supporting frame and the reinforlcement preferably incorporating elements for 5. transmitting the thrusts when the gate is operated.
The reinforcement preferably substantially comprises a metal sheet or a metal plate provided with elements firmly fitted thereto and projecting Otlt of its principal plane, the said elements creating the non-shift anchorage of the rein-10. forcement in the sliding plate against -tensile and brea~ing forces or thrusts.
The elements projecting out of the principal plane o: the reinforcement may be tabs integrally formed wi-th the sheet metal or metal plate of the reinforcement and bent to embrace 15. the sides and ends of the sliding plate. Alternatively the elements projecting from the principal plane of the reinforcement may be parts that have been bent out of the reinforcemen-t plate itself.
In another alternative the elements projecting from 20. the principal plane of the reinforcement rnay be indentations or corrugations formed in the sheet metal reinforcement or the reinforcement pla,te. In yet another alternative the elements projecting from the principal p'lane of the reinforcement may be projections such as pins welded to the sheet metal 25. reinforcement or reinforcement plate. In a further alternati~e the sheet metal reinforcement or the reinforcement plate may be perforated.
The elements for transmitting the thrusts which arise when the gate is operated rnay comprise ai~utment or elevations 30. on either side of the discharge passage of the molten metal KDNKJJP 14.

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1~3~ 5 through the s~pportlng frame, said abutments cooperating wi-th shoulders formed by the reinforcement.
The abutments on the supporting frame may extend across the direction of movement of the sliding plate and may 5. consist of ribs extending a distance correspor~ding to the width of the sl~ding plate and each cooperating with a complementary shoulder formed by the reinforcernent.
The elements on the supporting frame transrnitting the thrusts which arise ~en the ga-te is operated may comprise 10. a pin provided at least at one poin-t spaced away from the discharge passage for the molten metal, said pin engaging a reinforcement socket in the sliding plate~
The reinforcement may rest on three and preferably six bearing abutments on the facing surface of the supporting 15. frame.
Preferab]y at least three and preferably four of the bearing abutments are disposed symmetrically at a distance about the discharge passage for the molten metal, so that the sliding plate can freely bend slightly in the axlal direction in the region 20. surrounding the orifice.
The reinforcemen-l; contains an opening in the region of the discharge passage of the molten metal through the sliding plate, and this opening preferably has a diameter exceeding the diameter of the orifice, e.g. by an amount in the range of 25. 120 to 3009'.

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~3~ 5 The invention may be put i.nto practice in various wa~Js and certain specific ernbodiments w ll be descri~ed by way of ` example to illustrate the in~ention with reference to the : accompanying drawings, in which~
: 5. Figure 1 is a diagrammatic cross sectional view taken on the line I - I of Figure 2 of the middle plate of a th~ee-plate sliding gate nozzle apparatus containing a duct forrned therein in accordance with a first embodiment of the inventlon~
Figure 2 is a cross sectional view of the plate, taken 10. on the line II II of Figure 1) Figure 3 is a diagramrnatic plan view of a second embodi-ment of a middle plate in accordance with the invention con-ta ming a duct formed therein and a porous insert~
Figure 4 is a cross sectional view of the plate in 15. Figure 3, taken on the line IV - IV of Figure 3~
Figure 5 is a cross sectional view of a modification of the embodi.ment shown in Figures 3 and 4, taken on the line V - V of Figure 6, Figure 6 i.s a diagrammatic cross sectional view taken on 20. the line VI - VI of Figure 5 of the middle plate and of a partial plan v.iew of the bottom plate of the embodiment shown in Figure 5, Figure 7 is a diagrammatic cross sectional view taken on line VII - VII of Figure 8 of a third embodiment of a middle 25. plate in accordance with the invention, Figure 8 is a cross sectional view of the plate sho~n in Figure 7, taken on the line VIII - VIII of Figure 7, Figure 9 is a diagra~lmatic cross sectional view taken on the longitudinal centre line, of a fourth em~odiment of a 30. middle plate and of part of the bottom stationary plate in 1~3~ 5 accordance with the present inven-tion, Figure 10 is a cross sectional view of the ernbodiment sho in Figure 9, taken on the line X X of Figure 9, Figure 11 is a diagrammatic plan view of the upper surface 5. of the bottom stationary plate of the eMbodiment sho~ in Figure 9, Figure 12 is a diagrammatic cross sectional view from a~ove taken on the line XIV - XIV in Figure 13 of a fifth embodiMent of a middle p].ate in a three-plate sliding gate nozzle apparatus, 10. provided with a duct that can be directl.y heated, Figure 13 is a sectional view of the plate shown in Figure.
12 taken on the line XIII ~ XIII in Figure 12~
Figure 14 is a diagrarnmatic cross sectional view of a sixth embodiment of a middle plate of a 3-plate sliding gate 15. nozzle apparatus con^taining a gas-permeable inser-t embedded therein in accordance with the present invention, Figure 15 is a plan view of the~plate shown in Figure 14, Figure 16 is a cross sectional view of a 3-plate sliding gate nozzle apparatus for a vessel adapted -to hold a metal melt 20. showing a seventh embodiment of a middle plate in accordance with the invention which incorporates a gas-permeable insert embedded in the plate which is sho~m in the open position, Figure 17 is a cross sectional view corresponding to Figure 16 showing the middle or sliding plate in the partly 25. closed position, Figure 18 is a cross sectional view corresponding to Figure 16 showing the middle sliding plate in the closed position, Figure 19 is a cross sectional view of a 2-pla-te slidlng gate nozzle apparatus incorporating an eighth embodiment of 30. the invention namely a sliding plate having a gas-permeable K~NK/JP ~7 ~38~9~5 : insert embedded therein, Figure 20 is a cross sectional view of a ninth embodirQent of the invention, namely a nozzl.e containing a gas-permeable insert in the metal discharge passage of a vessel adapted to 5. hold a metal melt.;
Figure 21 is a diagrammatic sectional view demonstratirig the way in which the embodiment shown in Figure 2~ can be produced, Figure 22 is a cross sectional view taken on the line 10. XXll - XXII of Figure 21 of the gas permeable insert shol~m in Figure 21, Figure 23 is a diagrammatic cross sec-tional view of a tenth embodiment of the invention exemplified by a sliding plate containing a metal reinforcement;
15. Figure 24 is a view similar to Figure 23 showing a modi.fied form of construction, - Figure 25 is a plan view of an eleventh embodlment of the invention, Figure 26 is a longitudinal sectional view of the embodi-20. ment shown in Figure 25, - Figure 27 is a longitudinal sectional view of a twelth embodiment of the invention, Figure 28 is a longitudinal sectional view of a thirteerlt.h embodiment of the invention, 25. Figure 29 is a longitudinal sectional view of a fourteenth embodiment of the invention~
Figure 30 is a longitudinal sectional view of a fifteenth embodment of t;he invention, Figure 31 is a l.ongitudinal sectional view of a sixteenth 30. embodimen-t of the invention, KDNK~JP I p 1~31~

~ F`igure 32 is a view of the embodiment sho~n in Flgure 31 s~en from above, Figure 33 is a cross sectional view on the line XXXIII -XXXIII of Figure 32, 5. Figure 34 is a view of a seventeenth embodiment of the invention seen from above, Figure 35 and 36 illustrate one way of producing a sliding plate provided with a metal reinforceMent, and Figures 37, 38 and 39 illustrate another way of produci.ng 10. a sli.ding plate provided with a metal reinforcement.
~igures 1 and 2 illustrate a middle plate 112 of a con~
ventional three-plate sliding gate nozzle apparatu.s. Other parts of the apparatus are not shown since sliding gates as such are kno~n.
15. A duct 150 for conducting a gas or a liquid extends from an inlet opening 151 roughly in the middle of one of the longer sides around a discharge passage 106 to an outlet open.ing 152 in the other longer sideO
In an alternative arrangement(indicated by a dot-dash li.ne 20. 153) the duct 150 may extend further around the discharge passage 106.
In yet another alte~1ative the duct openings 151 and 152 may be formed in one end of the plate 112, preferably at the end where the mechanism for actuating the plate is located.
25. The duct 150 is preferably formed in the upper half of the plate 112, i.e. in that half which faces the metal melt, for example at a height equal to 20 to 50% of the thickness of the plate measured from the upper surface 141 of the plate 112.
The plate .L12 is made of refractory concrete suitable 30. compositions for ~vhich are given in Examples 1s 2 and 3 below.

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1~3~645 The duc-t 150 is formed for example by the provision of a steel tube in the mould and the refractory concrete is poured around the -tube. The concrete is then allowed to set, for example for 12 hours, and the plate is then taken out of 5. the mould and allowed fully to harden for another 48 hours at room temperature.
Instead of providing a steel tube a consumable material may be used to form the duct. Thus a tu~e made of cardboard or of a synthetic plastics material can be used which burns away 10. when casting begin~s. Alt~ natively a core of low melting metal, such as CERROBEND, an alloy of tin, or Rose's metal can be uscd.
This has the advantage that non-circular ducts of any desired cross section, such as rectangular or oval cross sections can be easily produced.
15. The CERROBEND material can be xemoved by the application of heat 7 for instance during the proGess of drying the plate.
The alloy will then melt and run out, a process that can be accelerated by blowing low pressure steam through the duct.
The discharge passage 106 may be bored through the cured 20. c.oncrete either with a diamond tool or preferably this passa~e is moulded during the pouring of the concrete by providing a removable core, and if the passage is cylindrical the core may be of split construction to faci]itate its extraction.
- Figures 3 and 4 illustrate a modified form of construction 25. of a middle pla-te 112 containing a cooling duct or heating duct 150 and a porous or gas-permeable insert 1560 The plate 112 is composed of two component parts, namely a body componen-t 160 and a separate cover plate 161 for the d~lCt.
The kody component 160 is first produced, as above descrlbed ~;itl 30. reference -to ~igures 1 and 2, by pouring the concrete into a mould which forms the duct 1~0, in the present instance formln~

KDl~K/JP 20 1~3E~45 an opèn groove and reba-ted ledges 162 and 16~ .or the cover 161.
The ledge 163 adjoins another recessed. portion 164 which penetrates to a greater depth into the body componen-~ part ].60 for the purpose of creating a gas distributing chamber surround~ng 5. a porous and gas-permeable insert 1560 The height of -the inser-t 156 is prefe.rably ..;lightly less than the depth of the led.ge i63 so that a clearance 167 remains between the cover 161 and -the inner face of the insert 156.
The cover 161 may be separately made of the same materlal 10. as the body component 160 and it may be cemented into position with the same refractory concrete (as indicated at 168). The cover 161 may be reinforced by casting a metal plate into the same.
Alternatively9 for some applications w~ere differences in 15. -thermal expansion are not very serious, a steel cover, preferably of stainless steel, might also be used.
The discharge passage 106 and the inlet 151 and out].et 152 may be produced in the same way as described with reference to Eigures 1 and 2. Al-ternatively they may be holes in the body 20. component 150 drilled with a diamond drill.
External valve means are preferably provided for the purpose of allowing a gas e.g. air or nitrogen.to enter through the inlet 151 and to leave through the outle-t 152 when the sl.Lding gate is ~pen, escape through the insert 156 being prevented 25. by the upper st~ionary plate (not shown), and in the closed position of the gate to enable the outlet 152 to be closed and to cause a gas preferably argon to be dlver-ted to the insert 156 w~ence it escapes through the discharge passage in the upper stationary plate and enters the molten metal.
30. In an al-cernative embodirnent the inlet and outlet openings, KDNK/JP 2l 1~31~ S

as lndicated at 170 and 171, may be formed in the cover 161 and arranged to comm~micate with the gas supply and return through suitably located grooves in the bottom stationary plate (not shown). Such an arrangement will be described in greater 5. detail wit.h reference to Figures 9 to 11. A special form of this arrangement for an outlet is illustrated in Figures 5 and 6 In this instance the outlet 171 from the plate 112 is formed in the cover 161 and leads across the undersurface of the plate 112 to the outside. The outlet 171 communicates with a longi-10. .tudinal groove 172 in the upper surface of the bo-ttom stationary plate 111. When the middle pl.ate 112 is in the casting pos.ition (open position) one end 173 of the groove 172 extends beyond the end of plate llZ thereby permitting the hot gas from the duct 150 to escape from the end 173 of the groove 172 in the 15. bottom plate 111. At the same time the length of the groove 172 is so determined that when plate 112 is moved from its open into its closed position, the groove 172 will be completely covered by plate 112 and the gas in the duct 150 will be forced to pass through the porous or gas-permeable insert 156 into the 20. melt in the metallurgical vessel. This form of construction ¦ clearly has the advantage of greater simplicity compared with the ¦ arrangement in Figures 7 and 4 and of providing automatic control ! f the gas.
I Figures 7 and 8 illustrate a modified form of the construc i 25. tion of Figures 1 and 2, which includes a porous or gas-permeable i inser-t 156. In this arrangement the middle plate 112 contains an insert 175 made of a normal ceramic material or of steel (ordinary or stainless steel) at the end 142 of the longer side of the plate. This facilitates the provision of the parts required ¦ ~0. for the gas supply connection and it also serves as a support .

KDNK/JP

1136~6-~5 for the porous insert 156 and the core for the duct 150 during ! production of the plate9 both being secured, for example, with a mastic, to the plate 112 whilst the concrete is being poured into the mould. The duct 150 extends into the proximity of the discharge passage 106 or in another form of construction it embraces the same as indicated at 153.
The duct 150 is flattish and extends at a level which is between 20% and 80S of the thickness of the plate 112 away from its upper face 141. The porous insert 156 is rectangular &nd 10. disposed between the arms of the duct 150.
In this forrn of construction the above-described CERROBEND
material may be used. The insertion 175 is placed on the bottom of the mould, the CERROBEND core defining the shape of duc~ 150 is formed and the porous insert 156 so located between the arms 15. of the duct that the CERROBEND material prevents the liquid refractory concrete from penetrating into the porous insert 156.
The concrete mass is then poured into the mould. After the casting has set and has been removed and allowed to cure the CERROBEND material i~ removed by heating or by blowing it out 20. with steam.
The discharge passage 106 is produced as has been described above and the upper and bottom surfaces of the plate are machined should this be necessary.
Figures 9 to 11 show another form OI ConStrUCtiQn of the 25. three-plate sliding gate in~hich the middle plate 112 as well as the bottom stationary plate 111 are of somewha-t different construction.
A porous insert 156 is located in the longer part of the middle piate 112 and supplied with gas from a pipe 180 30. through an upward,y recessed openin~ 1~1 in the insert 156.

KDNK/JP
~3 ~3F~ 5 The insert 156 and the pipe 180 are located on a metal plate 182 which has aln opening 188 opposite to a corresponding opening 189 pointing do~ ards at the end of the pipe 180. A metal pipe 184 is provided inside the plate 112 transversely there~
5. to between the insert 156 and the discharge passage 106 and this has an elltry 185 and an outlet 186 both pointing do~wards~ 185 comm~micating with duct 184~ and 186 with 184b which have openings in the undersurface of plate ].12.
As will be apparent from Figures 10 and 11 the bo-ttom 10. stationary plate 111 is provided with two parallel groo~es 190 and l91 in its upper face which are covered by the lGwer fase of the plate 112 and serve as gas ducts. The groove 190 extends from a metal or ceramic inserted component 192 ser~ing 8.S an inlet to the end of the plate 111 where it communicates with a 15. -cross groove 19~ extending only across about half the width o*
the plate 111. The other groove 191 extends from a point facing groove 193 to an outlet 194. In the open posi-tion of the plates 111 and 112 the cold gas is flowing through the opening 19~, the groove 190 and the opening 184a into the cooling t~lbe 184 from 20. whence it passes at the other end through the opening '84b and the groove 191 to the outlet 194, through which the hot gas havlng cooled the plate can freely and safely blow off into the at~.nosphere.
The pipe 180 is so d.isposed that when the plates 111 and 25. 112 are in the closed position (corresponding to a mo~ement of the sliding plate 112 from left to right),the opening 188 communicates with groove 193 and gas will be conducted from the entry 192 through the insert 156. The pipe 184 in this posi-cion is closed.
30. In Figures 12 and 1~ the !niddle pla-te 112 has a central KD~K/JP

1~31~16~

flattened duct 260 which reaches from one end of the plate 112 into the proximity of the discharge passage 106 where it divides into two oval ducts 261 and 262 that embrace the discharge passage 106 and have outlets at the other end O L the 5. plate 112. A burner nozzle 264 (or an air lance) is inserted into the entry opening of the flattened duct 160, permitting the~ plate 112 to be heated by hot combustion gases. When an air lance is used the pl~te 112 can be cooled by compressed air being blo~m through the plate.
10. Although not shown in the drawings the entry openings into the duct or ducts in a preferred form of construction may tangentially communicate with the ducts to improve circulation of the heating or cooling fluid. This arr~ngement is parti-cularly useful when the duct or ducts surround the discharge 15. passage.
Examples of refractory concretes are hereunder given, SUCh as may be used for the wearing parts that have been described above, and for making refractory parts provided with gas-permeable inserts, particularly for parts of sliding gate no~zles 20. associated with vessels holding molten metal.
EXample 1 80% by weight of an aggregate containing 40% by weight of A1203 and having a particle size from 0 to 5 mm are ~ixed with - 20% by weight of a fused alumina cement having a content of 25. 40% by weight of A1203, 12 litres of water being added in respect of each 100 kg of the dry mix.
For the production of a wearing part this mi~ is poured into a ~ould and compacted by vibration should this be desirable.
After having sufficiently set the concrete part is taken out of 30. the ~ould, stored to cure and dried.
KDNK/JP
~S ..

80% by weight of ~uyana bauxite containing 88~ by weight of A1203 particle size 0 to 5 mm was mixed with 20% by weight of alumina cement containi.ng 70~ by ~eight of A1203 5. and 10 litres of water per 100 kg of ~ry mix. This mix is further processed as described in Example 1~
However, if th~ plates are tobe used for casting st~els having melting points above 1500C whlch are cast at temperatures 50C to 60C above their melt.ing points, the conditions 10. which the plates have to wi-thstand are very much more severe and in order to ensure a more reliable service special compo~
sitions rnust be used.
These conditions consist in a very severe rnechanical erosive and chemical corrosive attack on the edges of the dis-15. charge passages of t~ plates combined with extreme thermalshock, the plates before the pour starts having a temperature of only 200C to 300C.
For such very severe conditions it is preferred to use refrac-tory concretes containing from 5 to 8% by weight of an 20. alumina cement, 2.5 to 4% by weight of a pulverent refractory material (having a particle size of less than 50 microns and I preferably less than 1 micron) such as a ~aolin or bentonite, micronised silica, micronised al~nina, micronised magnesia, micronised chromite or micronised fosterite, 0.01 to 0-30S' 25. by weight of an agent effective to increase the flowability of the composition comprising an alkali metal phosphate, alkali metal polyphosphate 9 alkali metal carbonate, alkali metal carboxylate OI' alkali metal hl~.ate and from 87.7 to 92o by weight of at least one refractory aggregate, desirably having 30. a particle size not exceeding 30 mm, an~ desirably all of which KDNK/JP
: . 2 6 ~386~

pass a 10 mrn mesh and about 25~ of which pass an 0.5 mrn mesh screen. The refractory aggregate may consist of calcined refrac-tory clay, bauxite, cyanite, sillimanite, andalusite, corundum, tabular alumina~ silicon carbide, 5. magnesia, chromite or zircon or mixtures thereof.
An example of such a concrete is given below:
Example ~
.
87.8 to 92% by weight of tabular alumina, particle size 0 - 6 mm are mixed with 5 to 8% by weight of alumina cement con-taining 10. about 80% by weight of A120~, 2.5 - 4% by weight of micronised alumina and 0.01 to 0.3% by weight of alkali metal poly-phosphate. 5 litres of water are added per 100 kg of dry mix.
The mix is poured into the mould and can be compacted by vibration.
15. Fi~ures 14 and 15 illustrate the sliding or middle plate 112 of refractory ooncrete of a 3-plate sliding gate nozzle apparatus in which a gas-permeable insert 156 ~s embedded.
The insert 156 may be a porous body consisting of a coarse-grained mass of corundum or mullite sintered with a small quantity 20. of a cementing agent and exhibiting a gas-permeability of at least 100 nanoperms.
The principal component of the sliding plate 112 is a pressed or cast body 200 containing a rectangular central window 201. In view of the relatively short-duration of a pour (from 25. the time of filling to the time of completely discharging the vessel) this body is heated to only a relatively low temperature, e.g. between 400 and 500C (when casting steel which heats up the walls of the discharge passage to more than 1500C).
For this reason it ls not absolutely necessary to m~ke -the body 30. 200 of a refractory material. More important is the choice of KDNK/JP

1~3~S

a material that is dimensionally particularly stable and insensiti~e to temperature shock of the described kind, so that this body 200 can serve as a durable frame for the actua] gating portion of the sliding plate 1127 5. The window 201 contains a member 202 which is of the same thickness as the body 200, but which has a slight clearance in the window 201 to facilitate replacement.
The member 202 has chamfered edges 203 and a cast-in cylindrical sleeve 205 which defines the discharge passage 106 10. for the metal through the sliding plate. This sleeve may be produced by pressing and firing or by casting a highly refractory mass. Without significantly increasing the cost of a sliding plate the sleeve may consist of a material of the highest quality, such as zircon, which can be standardised for size and shape 15. and which will consitute only a small part of the entire volume of the plate.
The member 202 consists of refractory concrete of a quality that should be chosen to allow for the aggressiveness of the molten metal in question. In the majority of cases a concrete 20. as specified above in Example 3 will sa-tisfy the needs of the case. I~ the member 205, as is preferred, is used, then the member 202 may be made of a lower quality, such as that described in Examples 1 and 2 above.
The member 202 contains the gas-permeable insert 156 embedded 25. therein supported by a metal plate 182 which has an opening 188 comrnunicating with an opening 189 at one end of a metal tube 180 of which the other end opens into a distributing chamber 208 at the bottom of the gas-permeable insert 156.
The gas-permeable inser~ 156, the tube 180, and the rnetal 30. plate 1~2 are assernbled and cemented or otherwise joined toge,~her, ~DI~K/JP

1~L3~

as indicated at 209; before the refractory concrete is poured.
~ igures 16, 17 and 18 illustra-te a 3-plate sliding gate nozzle apparatus in which the sliding plate 112 corresponds to the sliding plate in Figures ~ and 15. The fixed plates 5. are marked 110 and 111.
The lower fixed plate 111 is mounted in a supporting frame 131 in a prepared bed of mortar 1~1'. The metal dis-charge passage through the 3-plate slidi.ng gate nozzle apparatus is generally identified by 106~ but the sleeve for lining the 10. discharge passage has been omitted.
In its upper surface the lower fixed plate 111 contains a recess 154 which communicates wi~h a supply duct 155 and with a connecting gas pipe 157 for supplying the gas-permeable insert 156 with gas. When the gate is wide open, as in Figure 16 15. no gas can enterO
However, when the gate is partly closed, as in Figure 17, the gas entry opening is partly uncovered and some gas already passes into the discharge passage 106.
Finally, when the gate is fully closed as in E'igure 18~ the 20. gas supply is completely uncovered and the gas flows at maximllm rate into the discharge channel 106.
The recess 154 is so located in the lower ~ixed plate 111 and it is of a length such that during the closing movement of the sliding plate 112 the supply of gas to the gas-permeable 25. insert 156 through the gas pipe 157, the gas duct 155, the recess 154 and the tube 180 will begin when the gas-permeable insert 156 enters the discharge passage 106, and that a full rate gas supply to the gas-permeable insert 156 will be assur~d when the sliding p.late 112 is in closing position.
30. Figure 19 is an embod.iment of a 2-plate sliding gate KDl~K/JR

~3!~i45 nozzle appara~us in which 165 indicates a sliding plate co-operating with a fixed plate 169 which in its underfaoe - contains a recess 177 supplied with gas through a duct 183 and a gas supply pipe 183a.
5. The 2-plate sliding gate defines a metal discharge passage 106. The sliding plate 165 contains a gas-perrneable insert 156 which receives the gas through a duct 179 and a distributing chamber 178. The distributing chamber 178 is covered by a metal plate 178a. The gas is supplied in the 10. same way as described in the case of the 3-plate sliding gate ; in Figures 16, 17 and 18.
The fixed plate 169 is contained in a holder 174 and bedded in mortar 176.
~igures 20 to 22 illustrate the ninth embodiment of the 15. invention in its application to a nozzle brick or sleeve.
~, Figure-20 shows a nozzle brick 212 held in position in a mortar layer 21~ in the bottom b,rick 54 of a vessel adapted to hold molten metal.
Alternatively, the mortar layer 21~ could be replaced 20. by a jacket of fire-resistant felt or ceramic fibre material.
For the purposes of the invention it is of particular advantage to secure this jacket to the coned outer surface of the nozzle brick or sleeve 212 whilst the concrete is being poured. The , advantage thus achieved is of a dual nature. Though providing i 25. a good seal the jacket will 210t adhere to the internal wall of i the bottom brick 54. Hence the more rapidly wearing sleeve 212 can be easily removed without damage being done to the bottom brick 54, whereas on the othe~ hand the pre~ormed bond between the jacket and the sleeve ensures both correct positioning of 30. the sleeve and an easy removal of the jacket when the sleeve 212 is removed~
KDNK/~P
3v 1~3~6~4~i It is of the essence that the sleeve 212 should consist of a refractory concrete beGause the operationally safe application of such a ~acket which forms a layer of consistent thickness OAnA the peripheral surface of the sleeve 5. 212 demands the observance of close tolerances in Gverall dimensions and angles during the fahrica-tion of t~e sleeve.
This is assured ~Jhen using a refractory concrete. In the case of a burn-t material experieAnAce shows tha-t such close tolerances carAAlot be assured without resorting to expensive 10. subsequeAnt machining.
The refractory ceramic fibre and felt material is preferably 3 to 4 mm thick, its bulk weight is 170 to 210 kg/cub.rr., e.g. 1~2 kg/cub.m, and the fibre gauge is roùghly 3 to 4 microns. The material is preferably compressible to 15. half its thickness. If the sliding gate nozzle is to be used in the casting of a metal melt at temperatures up to about 1260C a suitable felt would contain about 52~o by weight of SiO2 and 48yO by weight of ~1203. For higher temperatures up to about 1500C it is advisable to make use of a felt based 20. on a chromium alurninium silicate having a content of for exa~ple 54.5% by weight of SiO2, 42.3% by weight of A1203 and 3.2%
by weight of Cr203 and a melting point above 1650C.
The sleeve 212 contains a gas-permeable insert 215 preferably surrounded b-y a metal cylinder 216 which leaves a 25. clearance creating a gas distributing chamber 217. The end of the cylinder 216 is sufficiently far a-r~y from the metal discharge passage 55 to be protected by -the insulating effect of the refrac-toAry concrete. A ga., duct 218 is provided and may be defined by a cast--in leng~;h of tube (not sho~n) or i-k 30. may be bored into the brickc The gas rnay -then be supplied to the pOl'OUS insert through a tube 21~ loca-ted bet~l~een the KDNK/JP
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1~31~S

ladle bottom and i-ts brick linin-g and emerging through the bottom 52 on the outside of the frame 5~ of the plate. If preferred the tube 219 might also be located bet~een the bottom 52 and the frame 58 above the fixed plate 67.
5. The sleeve 212 in Figure 21 may be produeed in a mould 222 by pouring with the provision of cores 220 and 221. The core 220 is introduced through the bottorn of the inve~ted mould form 222 and the metal sleeve 216 together with the insert 215 is placed on the metal disc 216a, which is held by the conical 10. part 223 of the core. If a jacket of refractory felt is to be interposed between the sleeve 212 and the nozzle brick -to form a seal, then a preformed coned felt jac~et 21~a is located inside the form. The core 221 is then positioned on the end of the core 220. The refractory concrete is poured into the form 15. and the moulding taken out when set to be stored until fully hardened. Finally the duct 218 is produced by drilling (see Figure 20).
~ igure 22 relates to particu]ars of a preferred geo-metrical configuration of the gas-permeable insert 215. This 20. has a generally square cross section and charnfered edges to enable it to fit into the cylindrical sleeve 216. The four cavities thus created represent a distributing chamber 217.
Communication between the several cavities is prcvided by peripheral groo~es 224 and 225.
25.
Gas-permeable or porous inserts for sliding gate nozzle apparatus fitted to casting ladles can be produced as follows:
Raw material: - High purity corundum of a particle size between O.5 and 3 mm and between 1 and 3 mm.
30. ~onding agent:-KDNK/JP

1~38~

a) Clay containing not less than 4390 A1203: up to 5 percellt byweight (particle size 0 to 0.25 mm).
b) Aluminium monophosphate : up to 1.5 percent ky weight ~50%
aqueous solution).
5. Bricks are compacted from this mix under a pressure of 500 to 600 kp/sq.cm. and the compacted masses are then kilned for not less than four hours at 1600C.
The physical properties of the bricks are:-Permeability to gas:- 500 to 700 nanoperm 10. Cold compressive strength:- 2~0 to 350 kp/sq.cm.
A few general explanations will be of assistance:- the proportion of open pores in volume percent is determined by the method of "Washburn". In this context it should be emphasised that the permeable pore ~olu~e may be only a 15. proportion of total porosity.
The gas permeability (according to DIN 51 058) is measured in nanoperm. 1 nanoperm corresponds to 10 9 perms.
A gas permeability of 1 perm is defined as the gas flow o~
1 cc/sq.cm/sec. driven by a pressure differential of one 20. dyne/sq.cm through a permeable body 1 cm thick, when the viscosity of the gas is 1 poise.
We refer now to Figure 23. This shows a moveable sliding plate 63 of a two-plate sliding gate nozzle for a vessel adapted to contain a metal melt. Such sliding gates are kr.o~m 25. in the art and the fixed plate of the gate is not therefore shown.
- The sliding plate 63 contains an orifice 55 for the passage therethrough of the metal melt. It is supported by a metal frame 64.
30. The side of -the sliding plate 63 facing away from its KDNK/JP

. . . ; . . .

1~3~64S

sliding face is provided wi-th a metal reinforcement 229 in the form of a flat metal sheet or a flat rnetal plate.
The reinforcement 22~ extends across the entire underface of the sliding plate 63 and it is connected to the plate so 5. that nei-ther tension, compression or shear forces can move it~
For transmitting the thrusts, which arise when the gate is operated, ~rom the supporting frame 64 to the sliding plate 63,the supporting frame 64 is formed with elevations 232 and 233 which co-operate with correspondingly shaped shoulders 10. 230 and 231 formed by the reinforcement 229. The elevations 232 and 233 on the supporting frame 64 may be ribs extending across the direction of movement of the sliding plate 63, the length of the ribs substantially equalling the width of the sliding plate 63.
15. It will be u~derstood that-the length and width of these ribs or elevations 232, 233 are arranged to comply with the demands that arise in any particular sliding gate nozzle. In Figure 23 the elevations 232 and 233 on the supporting frame 64 are disposed a relatively short distance away from the 20. orifice 55 for the passage of the metal, so that only com-paratively slight flexing of the sliding plate 63 can occur in use.
If it is desired that the sliding pla-te 63 should be capable of more pronounced bending the elevations 232 and 25. 233 on the supporting frame 6~ and the cooperating shoulders 230 and 231 of the sliding plate 63 may be spaced further apart and more particularly the elevation 232 and the shoulder 230 may be located nearer the end of the sliding plate 63 as is illustra-ted in Figure 24.
30. It will be understood -that the ?levations 232 and 233 KDNK/JP

~:4 1~3!~64S

on the supporting frame 64 and the shoulders 230 and 231 of the relnforcement 225 will be in dlrect engagement when the sliding gate is operated.
In the embodiment sho~m in Figures 25 and 26 the 5. reinforcement again comprises a flat metal sheet or a flat metal plate 235. The reinforcement extends over -the greater part of the underside of the sliding plate 112 and contains an opening 236 of a diameter exceeding the diameter of the orifice 106 for the molten metal. Preferably the diameter 10. of the opening in the reinforcement 236 may exceed the diameter of the orifice 106 by an amount ranging bet~een 120 and 300~o~ preferably from 140 to 2005o. Consequently when the refractory concrete is being poured during the production - of the sliding plate the gap between the orifice 106 and the 15. opening 136 in the rein~orcement will fill up with refrac-tory concrete and the reinforcement 235 will thus be sufficiently insulated frorn the teeming metal whilst casting proceeds.
The reinforcement 235 is provided wi-th six tabs 237 which are integra]ly formed on the edges of the reinforcement 20. and bent upwards to embrace the sides and ends of the sliding plate from the outside.
Figures 27 ~ 28 and 29 show three modified e~bodimen-ts of this type of reinforcement which in each case contains an opening 236 having a diameter exceeding that of the orifice 25. 106 as has abo~e been described.
~ In the embodi~nent sho~l in Figure 27 the reinforcement comprises parts 238 and 239 which have been bent out of t~le general plane defined by the reinforcement. In a ma~ner similar to the tabs 237 in Figures 25 and 26 thes~ bent parts 30. create a firm anchorage for taking up tension, c~mpression and KDI~l~;JJP

~3~

shear stress that may arise between the reinforcement and the body of the sliding plate 112, the allchorage or mechanical interlocking being created when the plate is being produced from refractory concrete by cas~ing.
5. In the embodiment sho~n in Figure 28, the reinforcement contains indentations or depressions 240 which in a sirnilar way also establish a secure anchorage between the reinforcernent and the body of the sliding plate. In a modification of this embodiment the depression 240 are replaced by punched up 10. perforated loops so that concrete can penetrate the loops and for~ a flush bottom face thereby increasing the interlocking , between the ref'ractory concrete and the metallic reinforcement.
In the embodiment shown in Figure 29 the only difference is that the reinf'orcement is perforated ~ 2~4/
15. In all these examples the upper sliding face of the sliding plate is manufactured so that it is parallel to the underface of -the reinforcement.
Figure 30 shows a three-plate sliding gate nozzle in which ~he sliding plate 112 has the f'orm shown in Figures 25 20. and 26. The fixed plates 110 and 111 of the sl:~din~ gate nozzle are provided with sheet metal reinforcement reser,1bling the sheet metal reinforcement 235, the upper fixed plate 110 being provided with the reinforcement on its upper surface and the lower fixed plale 111 on its underf'ace.
25. The sheet metal reinforcements are each formed with tabs 237, as in Figures 25 and 26~ and these tabs 237 embrace the sides and ends of the sliding plates ~ , 111 and 112 from the outside whil.st being embedded therein.
A supportin~ frame 118 is associated with the upper fixed 30. plate 110 and a supporting frame 131 with the lower fixed plate KDNK/JP
3~

` 1~31~i4S

111. Both frames 118 and 131 are provided with a plurality of pro-jections or bearing abutments 245 on their side facing the plate 110 or 111, and the sheet metal reinforcements 235 bear against these abubments. This ensures that the fixed plates 110 and 111 will be automatically fitted firmly and correctly without the need to use mortar.
Should it be desirable, sliding plates which are rein-forced in accordance with the invention may be reduced in thickness to less than the thickness attainable by conventional pressed and fired sliding plates. For instance, the ratio of length to thick-ness may exoeed 15:1, e.g. 20:1 to 25:1 or even m~re.
Figures 31 to 33 shGw a cast sliding plate 63 containing lengthwise and crosswide reinforcing elements formed on its under-side by l-sections 250 and 251 extending along both sides of the plate and interconnected by three welded transverse plates 252, 253 and 254.
Figure 34 shcws in plan view a sliding plate 312 which con-tains a metal reinforcement like the above described sliding plates although this cannot be seen in the illustrated view from above.
anly an opening 314 can be seen which is reinforoe d with sheet metal in a manner that will be later described with referen oe to Figures 35 to 39.
Bearing elements 315 indicated in discantinuous lines and conveniently for~ed by suitable elevations or abutments are provided on that side of the supporting frame (not here shown) which faoe s the sliding plate. m e reinforcement of the sliding plate 312 rests on these bearing elements. Consequently the rein~orced sliding plate 312 is freely suspended in the region of the discharge passage 106. The plate is j`:, . . ~.. .

1~3~

thus capable of slight deformation when subjected to the ef~ects of forces that arise in use.
The production of a sliding plate according -to this aspect of the in~ention will now be more particularly 5. described ~rith reference to Figures 35 to 3~.
Figure 35 shows a mould 401 in which the prepar~d rein-forcement 402 shown in Figure 37 is ~irst placed in position. In the illustrate~ case the reinforcernent 402 consists of a metal sheet (or plate) 4~3 containing a tubular sheet metal insertion 10. 404 covered by a cap 405. Projections, for instance in the fol~m of metal pins or bosses, 406, are welded to the sheet metal rein~
~orcement 403. These pins 406 serv~ to create a mechanical inter-lock and thus secure anchorage between the relnforcement 402 and the refractory concrete constitu-ting the sliding plateO In a 15. ~urth~r ~referred modifica~ion we provide the pins 406 with broad ened heads or tangs or recesses so as to increase the interlocking of the metal reinforcement to t}le refractory concr~te.
The bottom of the mould 401 contains holes 407 through which e~ectors 408 can be introduced -to eject, the finished 20. sliding plate from the mould 401. This action is illustrated diagra~natically in Figure 36.
At the inst,ant lllustrated in Figure 35 the mould 401 has been prepared for the production of the slidlng plate l~y pouring refractory concrete and compactinO the same, e.g. by 25c vibration. The mould 401 is thu.s filled with refractory concrete, the surolus concrete being skimmed off over the ed~e which is machined parallel to the bottom of' the mould 401.
It may be noted that the cap 405 may consist of any suitable ma~erial since its purpose ~s to pre~ent the 30. refractory concrete from entering the tubular reinforcernent insertion 404. However, if ~ormed as a welded on steel cap5 KDNK/JP

~3l3~

it could also ~ncrease the mechanical interlocking.
Figure ~6 as above mentioned, dia~rarnmatically shows the plate being Ipushed out o:E the mould as soon as -the concrete has initially set. The reinforce~ent sheet 402 serves as a 5. support and prev-ents the sliding plate frorn warping in storage and during further treatment (curing, drying and so forth). ~t the same time the mould 401 is thus again quickly available for lurther use.
Figure 33 diagrammatically shows a side elet~ation of 10. part of a supportiIlg frame 411 of conventional kind. Accordi7~g~
to the invention this supporting frame 411 is subsequently provided with a firmly fittec3 boss or stub 409 which is of a diameter so calculated that i-t will be a sliding fit in the tubular insertion ~l04, in the reinforcement 402. .4 flat disc 15. 412 embraces the boss 409.
Figure 7`9 shows the reinforced sliding plate 413 about to be assembled with the supporting frame 411. The reinforcing metal sheet 402 rests on the disc 412 ~hich absorbs the vertical forces, -transmitting the same through the supporting 20. frame 411 to ways not shown in the drawing. The boss 409 inside the insertion 404 provides anchorage for ~;he sliding plate against horizontal displacement in ~e supporting frame Lll without, ho~Yever, preventing hori20n-tal thermal expansion.
The boss 409 also takes up the entire thrust when the sliding 25. plate is operated. The transmission of this thrust by the boS5 409 through the reinforcement 402 to the concrete component of the plate 413 is effected by elevations 9 projections or stubs 406 and the tube 404.
The disc-shaped bearing member 412 on the illustrated 30. long side OI +he siiding plate corresponds to at least one Y,l)NK/JP
. ' ,~'7 `"` 1~3~

corresponding abutment on the short side not shown in the drawing, resembling the abutments 245 in Figure 30 and 315 in Figure 34.
In the above-described embodiment the resultant bending 5. stresses are taken up by the reinforcement~ In the same way as in the embodiment according to Figure 34 this affords the advantage that the sliding plate by bending will be relieved of undue compressive stress due to thermal expansion when locally heated in the nei.ghbourho~d of the discharge 10. passage forthe molten metal. Furthermore, the provision of these bearing abutments makes the reinforcement amenable to precise static calculation.
It must still be mentioned that the boss 409, if desiredS
may be provided with a central bore for the admission there-15. through of a gas.
Examples of refractory concretes which can be used forthe above sliding gate nozzles are described above in Examples 1, 2 and 3.
In a modification of the arrangements of Figures ~5 to 39 a hole is drilled in the supporting frame 41:L of a size to accornmodate the tube 404 which is extended downwardly through the reinforcing element 402 so as to engage the hole in the frame 411. This tube can then be used as a working fl~id inlet and within the plate can communicate with a duct for working fluid.

KDN~/JP

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of conditioning a refractory structure for use with molten metal having a duct for working fluid which comprises passing working fluid through the said duct.

2. The method as claimed in claim 1 in which the refractory structure is in the form of a plate for a sliding gate nozzle.

3. The method as claimed in claim 2 of pouring molten metal from a metallurgical vessel provided with a sliding gate nozzle at least the sliding plate of which is a refractory structure having a duct for working fluid which comprises passing heating fluid through the duct prior to moving the sliding plate from the closed position to the open position at least for the first pour.

4. The method as claimed in claim 2 of pouring molten metal from a metallurgical vessel provided with a sliding gate nozzle at least the sliding plate of which is a refractory structure having a duct for working fluid which comprises passing cooling fluid through the duct at least part of the time that molten metal is passing through a discharge passage in the plate.

5. The method as claimed in claim 2 in which the working fluid is a hot gas produced by combustion of a fuel so that the plate is heated at least in the vicinity of a discharge passage in the plate.

6. The method as claimed in claim 4 in which the working fluid is compressed air so that the plate is cooled at least in the vicinity of the discharge passage.

7. The method as claimed in claim 1 in which the working fluid is a gas which does not oxidize the molten metal involved.

8. A method as claimed in claim 4 which comprises using an inert gas to cool the plate at least in the vicinity of the discharge passage in its open position and for scavenging the discharge passage in its closed position.

9. A method as claimed in claim 4 of pouring molten metal from a metallurgical vessel provided with a sliding gate nozzle having a combination of sliding plate and fixed plate in which the working fluid is selected to be one which does not oxidize the molten metal whereby gas may be used to scavenge the discharge passage while the gate is closed and to cool the plate at least in the vicinity of the discharge passage while the gate is open.

10. A method as claimed in claim 8 in which the inert gas is switched from cooling to scavenging automatically by way of the closing movement of the sliding plate.