Lid for ladle

Abstract

A lid for a ladle comprising a body which has a central axis defining an axial direction is described. The body is provided with an edge at which, in use, the lid rests on an upper edge of a ladle, to close the ladle from the top. Advantageously, the lid comprises a plurality of telescopic rods jutting, one after the other, from the edge along respective longitudinal axes parallel to the axial direction. Each telescopic rod is telescopically extendable, independently of the others, in a longitudinal position between, or equal to, a fully extracted position of the telescopic rod in the lid and a retracted position of the telescopic rod from the lid, correspondingly to the distance, considered for each telescopic rod, between the edge of the lid and the upper edge of a ladle. One or more telescopic rods are preferably hollow and connected to an air inflow line and have one or more nozzles facing one or both of the adjacent telescopic rods. The nozzles are adapted, in use, to generate an air blade along the edge of the lid by means of the pressurized inflow air, so as to limit the amount of heat and / or fumes dispersed outside of the ladle.

Description

[0001] Lid for ladle

[0002] ***

[0003] DESCRIPTION

[0004] Field of the invention

[0005] The present invention concerns the iron and steel field and particularly concerns a lid of a ladle preferably used in a preheating station for a ladle.

[0006] Known art

[0007] As known, during the production process of metal products in foundry, such as for billets, tubes, bars, wheels or railway axles, appropriate vessels are used to contain molten metal. Such vessels are known under the name of ladles. A ladle is precisely a container provided with a cylinder-shaped body provided with an inner cavity coated on the inside with refractory material able to withstand contact with molten metal. In the context of the present application, molten metal can be understood as pure metal, such as for example aluminum, or a ferrous alloy for producing steel.

[0008] The body of the ladle has an outer surface intended to stay in contact with the outer environment and an inner surface actually coated with refractory material intended to come into contact with the molten metal. Moreover, a circular-shaped base, at which the ladle can be rested on the ground or a respective carriage, and an upper body, positioned at the opposite end from the base, also circular-shaped and which delimits the mouth of the inner cavity, can be distinguished in the body of the ladle.

[0009] There are ladles of different capacities: those of greater dimensions can contain up to 400 tons of molten metal.

[0010] All are similar in that they are used for transporting the molten metal from a first station of a foundry to a second station of a foundry. Typically, ladles are used for transferring the molten metal from the melting furnace (for example an electric furnace), where the metal is precisely melted, to the station where the molds, or casts, are located, where the molten metal is poured into the molds (tapping operation) and solidifies to form the desired metal products. In order to ensure that the temperature of the molten metal does not drop excessively and / or too suddenly when it is poured into the ladle, it is now customary to pour the molten metal into a ladle which has previously been heated.

[0011] In particular, the refractory material coating the inner surface of the body of the ladle is heated.

[0012] The heating of the ladle occurs in appropriate preheating stations. Such preheating stations can essentially be constituted of a machine comprising a movable arm at the end of which there is a lid intended for being positioned on the upper edge of the ladle to be heated. Such preheating stations are of the vertical type, i.e. extend along their own axis perpendicular to the ground.

[0013] As an alternative, there are preheating stations which extend along their own axes parallel to the ground (preheating stations of the horizontal type) and which are provided with one or more carriages on which a lid, intended to be brought to abutment on the upper edge of a ladle to be heated, is placed.

[0014] Examples of preheating stations are described in US 4 364 729, JP H11 28562 and DE 12 13 088.

[0015] As known, a lid for ladle is circular-shaped and comprises a lower surface intended for closing the ladle and an upper surface, opposite the lower surface, at which the lid is constrained to the arm of the machine.

[0016] A lid for ladle according to the preamble of claim 1 is described in US 4 364 729.

[0017] As known, the lid is provided with a burner positioned in the center, at the lower surface, which provides the energy required to heat the refractory material of the ladle.

[0018] The lid can also be equipped with a recovery system of the fumes generated by the burner when preheating the ladle.

[0019] In practice, in a first step, the ladle (devoid of molten metal) is brought to the preheating station where it is closed with its respective lid: the lid is laid down on the upper edge of the ladle, therefore closing the inner cavity of the lid from the top.

[0020] At this point, the burner is lit so as to heat the refractory material. Usually, the burner heats the inside of the ladle until the refractory material reaches approximately 1000°C.

[0021] Once the desired temperature has been reached, the burner is turned off, the lid is moved away from the ladle by exploiting the movable arm to which it is constrained and the ladle is brought near the melting furnace from where the molten metal is poured directly into the inner cavity of the ladle itself. Following the pouring step, the ladle with the molten metal is brought to stations for purifying or enriching the molten metal and, finally, to the tapping station, in which the molten metal is poured into molds or casts. At this point, the ladle is once again empty and is brought back to the preheating station, where another work cycle is initiated.

[0022] It is known that whenever the molten metal is poured from the melting furnace into the ladle or poured from the ladle into the molds, parts of molten metal end up on the upper edge of the ladle and solidify there almost instantly. This solidified slag of molten metal is formed randomly, therefore is distributed on the upper edge of the ladle in a non-homogeneous way and have different shapes from one another, i.e. some are higher than others or have a greater extent than others.

[0023] Since the same ladle is used for several work cycles, the number of solidified slag on the upper edge increases over time.

[0024] The presence of such slag impedes the lid of the preheating station from perfectly laying down on the upper edge of the ladle; it actually defines, with the ladle, empty spaces precisely due to the slag of molten metal solidified on the upper edge of the ladle itself.

[0025] This is, for example, schematically depicted in figure 10.

[0026] A portion of a ladle 200, made in a known way and provided with an upper edge 201 delimiting an inner cavity 202 coated with a refractory material 203, is shown in this figure. Various solidified slag of molten metal is present at the upper edge 201. For example, the solidified slag identified with the number of reference 250 has greater height and length than those of the solidified slag identified with the number 251. Moreover, the solidified slag 250 itself is of irregular shape, i.e. does not have a constant height but has various peaks. For example, the peak 251a has a height greater than the peaks 251 b and 251c which are arranged on opposite parts with respect to the peak 251a.

[0027] A lid 252 of a ladle 200 made according to the known art is moreover depicted in figure 10. The lid 252 has an edge 253 which should rest directly on the upper edge 201 of the ladle 200 but which instead, due to the presence of the solidified slag 250, stays spaced from the upper edge 201 , therefore defining empty spaces 254, 255 therewith.

[0028] The lid 252 actually rests on the peak 251a of the solidified slag 250 and defines, with the ladle 200, an empty space 254 to the left and an empty space 255 to the right of the peak 251 a.

[0029] It is known that, at the empty spaces defined between the lid and the ladle, a non-negligible heat loss occurs during the ladle preheating process which forces to use the burner of the lid for a long duration and / or high intensity, with a consequent increase of the fuel used (usually methane) and respective costs.

[0030] It is therefore clear that there is a need to find a solution which allows to minimize the heat loss during the ladle preheating step.

[0031] Summary of the invention

[0032] Object of the present invention is to provide a lid for a ladle which is easy to use and which allows, when laid down on a ladle, to limit the heat loss and / or fumes dispersion outside of the ladle on which the lid is positioned.

[0033] A further object of the present invention is to provide a lid for a ladle which allows, in use, to decrease the costs related to the preheating of the ladle.

[0034] A first aspect of the present invention therefore concerns a lid for a ladle according to claim 1 . The lid for a ladle according to claim 1 comprises, in a known way, a body which has a central axis defining an axial direction. The body is provided with an edge at which the lid is adapted to rest on an upper edge of a ladle, to close the ladle.

[0035] In practice, the lid preferably has a lower surface, or first surface, intended, in use, to face the inner cavity of a ladle, and an upper surface, or second surface, opposite the lower surface. The edge of the lid is precisely provided at the lower surface. For the purpose of the present invention, the lower surface and the upper surface are identifiable as such also if the lid is intended to be positioned on the upper edge of a ladle extending parallel to the ground.

[0036] According to the invention, the lid comprises a plurality of telescopic rods jutting, one after the other, from the edge, i.e. arranged in series or in succession to one another. In practice, the telescopic rods are arranged on the perimeter of the edge and are jutting from the edge. Each telescopic rod extends on a respective longitudinal axis parallel to the axial direction. Moreover, each telescopic rod is telescopically extendable in a longitudinal position between, or equal to, a retracted position of the telescopic rod in the lid and a fully extracted position of the telescopic rod from the lid. In practice, each telescopic rod can extend longitudinally in a fully extracted position, in a retracted position or in a multiplicity of longitudinal positions intermediate between the retracted position and the fully extracted position.

[0037] In practice, the longitudinal position of each telescopic rod is determined, in use, by the telescopic rod in abutment against the upper edge of the ladle or against any solidified slag of molten metal present on the upper edge of a ladle.

[0038] The telescopic rods are preferably jutting downward from the edge of the ladle (obviously if the lid is kept in the horizontal position with respect to the ground). Since lids are conventionally circular-shaped, they are arranged circumferentially with respect to the central axis, which also is the symmetry axis of the lid. Each telescopic rod extends telescopically independently of the others; the magnitude of the longitudinal extent of the telescopic rods is not actually predetermined or does not depend on the longitudinal extent of the adjacent telescopic rods but only depends, for each telescopic rod, on possible irregularities present on the surface of the upper edge where each telescopic rod abuts.

[0039] Actually, as is known, solidified slag of molten metal, generated randomly and which therefore does not have homogeneous shape and distribution, is often present on the upper edge of the ladle.

[0040] Each telescopic rod therefore is adapted, i.e. extends telescopically, correspondingly to the presence or absence of such solidified slag and to the height from the upper edge of such solidified slag; for example, the telescopic rods which go into abutment on solidified slag of greater height extend for a lesser length, while the telescopic rods which go into abutment on solidified slag of lesser height or which go into abutment directly on the upper edge extend for a greater length.

[0041] In practice, once the lid has been positioned on the ladle, each telescopic rod extends telescopically, independently of the others, longitudinally on its own axis for a length equal to the distance, considered at each rod, between the edge of the lid and the upper edge of the ladle, or between the edge of the lid and any solidified slag of molten metal present on the upper edge of the ladle.

[0042] Each telescopic rod autonomously and automatically extends longitudinally correspondingly to the irregularities on the surface of the upper edge of the ladle, i.e. without requiring an external operator to program the magnitude of the longitudinal extent of the telescopic rods or to intervene to determine the longitudinal extent from time to time.

[0043] A first advantage of the use of a lid of the present invention is therefore that it automatically adjusts to the irregularities present on the upper edge of the ladle by resting at several points on the upper edge of the ladle (i.e. at each telescopic rod) and not exclusively on the solidified slag of greater height, as occurs in the lids according to the known art.

[0044] This allows to form a real physical barrier constituted by the very presence of the telescopic rods, which limits the amount of fumes and / or heat which can escape from the space defined between the lid and the upper edge of the ladle. This way, the amount of energy, which, in use, is dispersed by the ladle when the lid according to the invention is arranged thereon, is limited.

[0045] According to a preferred embodiment, the lid according to the present invention is a lid of a preheating station for a ladle. The use of the lid according to the present invention therefore allows to limit the amount of heat generated by a burner, which heat would otherwise be dispersed outside of the ladle when using lids according to the known art.

[0046] According to an alternative embodiment, the lid according to the present invention is a lid usable for covering a ladle containing molten metal during transport of the ladle from a first station of a foundry to a second station of a foundry. Also in this circumstance, it is clear that the lid allows to limit the heat loss outside of the ladle, therefore contributing to keep high and constant the temperature of the molten metal in the ladle itself.

[0047] In practice, the presence of the telescopic rods allows to reduce the amount of fumes and / or heat dispersed outside of the ladle through the space defined between the edge of the lid and the upper edge of the ladle. In practice, the telescopic rods fully or partly close this space between the edge of the lid and the upper edge of the ladle.

[0048] Firstly, this allows to keep a higher temperature inside the ladle, because it limits the amount of heat and fumes dispersed outside of the ladle. Moreover, if a device for recovering fumes and a respective heat exchanger are combined with the lid, the lid according to the present invention allows to increase the percentage of recovered fumes and, therefore, also the amount of heat reused for heating the burner’s combustion air or for heating a basket, or box, for metal scraps.

[0049] In light of the characteristics described above, a technician of the field will be able to implement the lid according to the present invention such as to limit, or prevent, that, in use, heat and / or fumes are dispersed from the ladle.

[0050] In practice, depending on the dimensions of the lid and on any specific requirements, a technician of the field will be able to determine a number of telescopic rods appropriate for achieving this purpose. Generally, the telescopic rods can be cylinder-shaped; it is however clear that it is possible to use telescopic rods of any other shape. Moreover, it is possible to make the lid with one or more telescopic rod assemblies grouped together.

[0051] For example, it is possible to make a lid of a diameter of approximately 3090 mm and provided with 55 cylinder-shaped telescopic rods. The distance between two adjacent telescopic rods is approximately 117.5 mm and the angle defined between the longitudinal axes of two adjacent telescopic rods is 6.55°.

[0052] Or, it is possible to make a lid of a diameter of approximately 2300 mm and provided with 40 cylinder-shaped telescopic rods. The distance between two adjacent telescopic rods is approximately 117.5 mm and the angle defined between the longitudinal axes of two adjacent telescopic rods is 9°.

[0053] As an alternative, it is possible to make a lid of a diameter of approximately 1500 mm and provided with 25 cylinder-shaped telescopic rods. In this case, the distance between two adjacent telescopic rods is approximately 116.5 mm and the angle defined between the longitudinal axes of two adjacent telescopic rods is 14°.

[0054] Or, it is possible to make a lid of a diameter of approximately 3090 mm and provided with 13 telescopic rod assemblies: each assembly extending along an arc of a circle and comprising ten telescopic rods grouped into a single semicircular body. The distance between two adjacent assemblies is 60 mm.

[0055] It is therefore clear that, depending on the cases, it is possible to provide and make telescopic rods in different numbers and shapes (for example 25 telescopic rods, 40 telescopic rods, 55 telescopic rods or 110 telescopic rods).

[0056] The distance between two adjacent telescopic rods of said plurality of telescopic rods (or the distance between adjacent assemblies of telescopic rods) is preferably at most 150 mm, still more preferably such distance is at most 117.5 mm.

[0057] In other words, the telescopic rods have an arrangement such that, taking any two adjacent telescopic rods, the distance between those telescopic rods is at most 150 mm, still more preferable such distance is at most 117.5 mm.

[0058] In this context, no preferred minimal distance between two adjacent telescopic rods is identifiable because the telescopic rods can also be arranged flush one another.

[0059] The telescopic rods are preferably arranged equidistant from one another, i.e. the same angle is defined along the whole circumference between two adjacent telescopic rods with respect to the central axis.

[0060] One or more telescopic rods, and still more preferably all the telescopic rods, are preferably hollow and connected to an air inflow line. These telescopic rods have one or more nozzles facing one or both of the adjacent telescopic rods, i.e. in front of one or both of the adjacent telescopic rods. In practice, the nozzles open, at an end, into the cavity of the corresponding telescopic rod and outward at the other, toward the adjacent telescopic rods.

[0061] Since these nozzles open into the cavity of the respective telescopic rod, they are in fluid communication with the air inflow line; therefore, in use, when air is supplied to the inflow line, an air blade is generated by the nozzles along the edge of the lid, i.e. toward the adjacent telescopic rods, which air blade allows to further limit the amount of heat and / or fumes dispersed outside of the ladle and recovered, for example, by a device for recovering fumes. In practice, considering any two adjacent telescopic rods, they are positioned at a distance from one another that the air blade produced by the respective nozzles is able to limit, or prevent, the heat loss and / or fumes dispersion. In practice, thanks to the presence of the telescopic rods and the air blade, a barrier is generated, which limits or prevents the heat loss and / or dispersion of fumes generated, in use, in the ladle. The nozzles are preferably made as through holes.

[0062] The nozzles can be designed to generate a pressure, or compressed, air blade, or can be designed to generate a ventilated air blade. In alternative, some nozzles can be designed to generate a pressure air blade and others to generate a ventilated air blade.

[0063] The air blade can possibly be enriched with sprayed water by using a sprayer.

[0064] Each telescopic rod preferably comprises a fixed portion integral with the lid and provided with an inner cavity extending along the corresponding longitudinal axis, a movable portion coaxially and telescopically inserted into the inner cavity of the fixed portion and a resilient element arranged between an end of the fixed portion and the movable portion.

[0065] The fixed portion and the movable portion are preferably made cylindershaped.

[0066] The resilient element allows to counteract the movement of the second movable portion toward the fixed portion. In practice, the resilient element constantly pushes the movable portion away from the fixed portion, i.e. to the fully extracted position. When the lid is laid down on a ladle, the resilient element of each telescopic rod is contracted correspondingly to the distance, considered for each telescopic rod, between the edge of the lid and the upper edge of the ladle or correspondingly to the height of the solidified slag of molten metal.

[0067] Once the lid is raised from the ladle, the telescopic rods return to the fully extracted position because the resilient elements push the movable portion away from the fixed portion.

[0068] The movable portion is preferably movable with respect to the fixed portion between the retracted position, at which the distance between the movable portion and the edge of the lid is minimal or null, and the fully extracted position, at which the distance between the movable portion and the edge of the lid is maximal, and vice-versa. In the extension movements, the movable portion can assume various intermediate positions between the retracted position and the fully extracted position, such as to be able to adapt itself to the multiple heights the solidified slag of molten metal can have.

[0069] The fixed portion preferably comprises a first end inserted into the lid and distal from the edge and a second end, opposite the first end, positioned at the edge: the second end defines a central hole into which the movable portion is slidably inserted.

[0070] The second end of the fixed portion preferably has a ring jutting toward the respective longitudinal axis and which actually defines the central hole into which the movable portion is inserted. In particular, when the movable portion is pushed by the resilient element to the completely extracted position, it is in abutment on this central ring at its own base. In practice, the central ring acts as a limit stop for the movable portion. Actually, the movable portion preferably comprises a base constantly housed in the fixed portion, and a stem jutting downward from the base and which is intended to go into abutment on the upper edge of a ladle.

[0071] The movable portion preferably has:

[0072] - a first end constantly housed in the fixed portion and at which the movable portion has a base where the resilient element is housed, and

[0073] - a second end, slidable outside of the fixed portion and formed on a stem jutting from the base.

[0074] The second end is preferably designed for going into abutment on the upper edge of a ladle or a solidified slag of molten metal. For this reason, at the second end a through hole can be formed, or a nozzle is provided, at the longitudinal axis. This hole allows to form an air blade which allows to limit the dispersion of fumes and / or heat loss also if it should abut on an irregular or inclined surface.

[0075] The pressurized air inflow line preferably opens into the inner cavity of the fixed portion, and the inner cavity of the fixed portion is in turn in fluid communication with an inner cavity of the movable portion. The inner cavity of the movable portion is therefore in fluid communication with the air inflow line.

[0076] Said one or more nozzles are preferably provided in the movable portion and open into the inner cavity of the movable portion. For this reason, in use, the nozzles are adapted to generate an air blade along the edge of the lid by means of the inflow air supplied to the telescopic rod by the air inflow line.

[0077] Each of said one or more nozzles preferably extend parallel to the longitudinal axis for at least 9% of the length of the telescopic rod.

[0078] Said one or more telescopic rods preferably each comprise two or more nozzles provided longitudinally and at different heights and which are alternately positioned in opposite portions of the telescopic rod.

[0079] An angle of approximately 6.55° and 14°, between the longitudinal axes of two adjacent telescopic rods, is defined with respect to the central axis. For example, approximately 6.6°.

[0080] The lid is preferably a lid of a preheating station for a ladle, i.e. a station designed for heating the refractory material of the ladle in a uniform way before the molten metal is poured therein. It can therefore comprise a burner adapted, in use, to generate a flame to heat the refractory material coating the inner cavity of the ladle and / or a device for recovering fumes generated, in use, inside a ladle.

[0081] In its second aspect, the present invention concerns a preheating station according to claim 22 and which, thanks to the use of a lid according to the present invention, allows to limit the amount of fumes and / or heat dispersed into the environment during the ladle preheating operation.

[0082] In its third aspect, the present invention concerns a recovery system of the heat generated by a burner of a preheating station, according to what is claimed in claim 23. In addition to a preheating station, the heat recovery system also comprises:

[0083] - a heat exchanger coupled to the recovery system of the fumes, which is arranged to recover part of the heat of the fumes recovered by said device for recovering fumes and to release said heat to the burner’s combustion air, and / or

[0084] - at least one conduit coupled to the device for recovering fumes, said at least one conduit being adapted to convey the recovered fumes to a basket, or box, arranged to house scrap metals.

[0085] Thanks to the use of the lid according to the present invention, which allows to reduce the dispersion of fumes and / or heat loss outside of the ladle and to consequently increase the percentage of heat recovered by the heat exchanger, this heat recovery system allows to reduce the amount of fuel used to preheat the ladle itself.

[0086] In its fourth aspect, the present invention concerns a method for limiting the amount of heat and / or fumes dispersed by a ladle, according to what is claimed in claim 24. In this method, it is preferably possible to use a lid for ladle according to what is described above.

[0087] Brief list of the figures

[0088] Further characteristics and advantages of the invention will become clearer in the review of the following detailed description of its preferred, although not exclusive, embodiments illustrated by way of example and without limitations with the aid of the accompanying drawings, in which:

[0089] - figure 1 is an elevated section of a portion of an assembly constituted of a ladle 200 and of a respective lid 1 according to a first embodiment of the present invention, provided with telescopic rods 6;

[0090] - figure 2 is a bottom plan view of the lid 1 shown in the figure;

[0091] - figure 3 is a detail of figure 2;

[0092] - figure 4 is a section considered with respect to a plane tangential to the edge 4 of the lid 1 shown in figure 1 ;

[0093] - figure 5 is a schematic sectional view, considered with respect to a radial plane of the lid 1 shown in figure 1 , in which the telescopic rods 6 are all in the fully extracted position;

[0094] - figure 6 is a schematic sectional view, considered with respect to a radial plane of the lid 1 and of the ladle 200 shown in figure 1 , where the telescopic rods 6 are in the retracted position;

[0095] - figure 7 is a schematic sectional view, considered with respect to a radial plane of the lid 1 and of the ladle 200 shown in figure 1 , where the telescopic rods 6 are in an intermediate position between the fully extracted position and the retracted position;

[0096] - figure 8 is a front view of a heat recovery system comprising two preheating stations 36 arranged vertically and two preheating stations 39 arranged horizontally;

[0097] - figure 9 is a top view of the heat recovery system shown in figure 8;

[0098] - figure 10 is a section, considered with respect to a plane tangential to the edge of a lid of a ladle according to the known art, in which it is possible to observe that the lid rests on the ladle at the slag of molten metal of greatest height;

[0099] - figure 11 is a bottom plan view of a second embodiment of a lid T according to the present invention;

[0100] - figure 12 is a bottom plan view of a third embodiment of a lid 1” according to the present invention;

[0101] - figure 13 is a bottom plan view of a fourth embodiment of a lid T” according to the present invention.

[0102] Detailed description of the invention

[0103] With reference to figures 1-7, a preferred embodiment of a lid according to the present invention and adapted to close a lid from the top will be described hereunder. Such embodiment corresponds to a first embodiment.

[0104] In the accompanying figures, the lid of the ladle is generally denoted by the number of reference 1 , whereas the ladle is identified with the number of reference 200. The lid 1 is preferably a lid of a preheating station 36 of the type shown in figures 8 and 9.

[0105] The ladle 200 is a ladle according to the known art (i.e. of the type previously described with reference to the known art) and has an upper edge 201 delimiting an inner cavity 202 coated with refractory material 203.

[0106] In the context of the present invention, the lid 1 and the respective ladle 200 will be described by keeping in mind how they are normally used in the iron and steel field.

[0107] For example, in figure 1 , it is therefore possible to observe that the lid 1 has a body 2 with an upper surface 3 and a lower surface 4.

[0108] In use, the body 1 rests on the ladle 200 at the lower surface 4, i.e. the lower surface 4 is facing the ladle 200, i.e. downward, and closes the inner cavity 202 of the ladle itself from the top.

[0109] The upper surface 3 is facing in the opposite direction with respect to the lower surface 4, i.e. upward, and is intended, in use, to stay in contact with the outer environment. As shown in figure 9, the lid 1 can be constrained to one or more arms 36b of a preheating station 36 at the upper surface 3.

[0110] The body 2 has a central axis shown in figure 2, which is directed toward the observer in this figure. The central axis X is preferably also the symmetry axis of the lid, i.e. the body 2, except for minimal construction differences, is symmetric with respect to the central axis X. Actually, the lid is preferably circular and extends with respect to the central axis X. The central axis X also defines an axial direction of the lid 1 .

[0111] Returning to figure 1 , it is possible to observe that the body 2 is concave toward the bottom and has an edge 5 at which the lid rests on the ladle 200.

[0112] Unlike known lids for ladle, the lid 1 has a series of telescopic rods 6 jutting from the edge 5 at the lower surface 4.

[0113] In the radial section shown in figure 1 , a single telescopic rod 6 is shown (in section); shifting the attention to figure 2, it is possible to notice that telescopic rods 6 are arranged, one after the other, along the whole edge 5 of the lid 1 . In practice, the telescopic rods 6 are arranged circumferentially on the edge 6.

[0114] For example, it is possible to make a lid of a diameter of 3090 mm provided with fifty five telescopic rods and intended to close a ladle of a diameter of 3060 mm. In this case, the distance between two adjacent telescopic rods 6 is 117.5 mm. Such distance is calculated with respect to the movable portions 8 of the corresponding telescopic rods 6. The angle defined between the longitudinal axes Y of two adjacent telescopic rods 6 is 6.55°.

[0115] As an alternative, it is possible to make a lid T shown in figure 11 of a diameter of 2300 mm and with 40 telescopic rods 6. Also in this case, the distance between two adjacent telescopic rods 6 is 117.5 mm. Such distance is calculated with respect to the movable portions 8 of the corresponding telescopic rods 6. The angle defined between the longitudinal axes Y of two adjacent telescopic rods 6 is 9° (as shown in detail in figure 11).

[0116] Or, it is possible to make a lid 1” shown in figure 12 of a diameter of 1500 mm and with 25 telescopic rods. In this case, the distance between two adjacent telescopic rods 6 is 116.5 mm. Such distance is calculated with respect to the movable portions 8 of the corresponding telescopic rods 6. The angle defined between the longitudinal axes Y of two adjacent telescopic rods 6 is 14° (as shown in detail in figure 12).

[0117] It is therefore clear that a technician of the field will be able to make a lid for ladle in which the number and distance of the telescopic rods are such as to allow to limit, or eliminate, the heat loss and / or fumes dispersion from a ladle while using it.

[0118] Moreover, a further embodiment representing a lid T” in which several telescopic rods 6 are grouped into an assembly 40 is shown in figure 13. In particular, the lid T” comprises thirteen assemblies 40, each comprising ten telescopic rods 6 grouped into a single body 41. Each assembly 40 extends along a circumferential portion of the lid T”. The distance between two adjacent assemblies 40 is 60 mm.

[0119] Returning to figure 1 , it is possible to observe more precisely how each single telescopic rod 6 can preferably be made.

[0120] What is described with reference to the telescopic rod 6 shown in figure 1 can also therefore be applied to the other telescopic rods of the lid 1 shown in figure 2.

[0121] The telescopic rod 6 extends on a longitudinal axis Y parallel to the axial direction defined by the central axis X, so as to be orthogonal with respect to the upper edge 201 of the ladle 200.

[0122] The stem is defined as “telescopic” because it has a fixed portion integrally inserted into the lid 1 (denoted by the reference number 7) and a movable portion 8 coaxially inserted into the fixed portion 7.

[0123] The fixed portion 7 and the movable portion 8 are cylinder-shaped and the movable portion 8 has a smaller diameter than the fixed portion 7.

[0124] For example, the fixed portion 7 has a length of approximately 225 mm and a diameter of 76 mm, whereas the movable portion 8 has a length of 280 mm and a diameter of approximately 48.3 mm.

[0125] The movable portion 8 is slidably inserted into the fixed portion 7, i.e. is susceptible of longitudinal displacements, along the longitudinal axis Y, with respect to / in the fixed portion 7 itself.

[0126] A resilient element 9, for example a spring, is arranged between the fixed portion 7 and the movable portion 8 and counteracts the movements of the movable portion 8 toward the fixed portion 7.

[0127] The movable portion 8 can actually slide in the fixed portion 7 in a first direction and in a second direction opposite the first direction.

[0128] In detail, the movable portion 8 is movable between a retracted position in the fixed portion 7 and a position fully extracted from the fixed portion 7, and vice-versa.

[0129] A series of telescopic rods 6 with the movable portion 8 in the fully extracted position is shown in figure 5, while the telescopic rods 6 (those closest to the observer) with the movable portion 8 in the retracted position are shown in figure 6.

[0130] By comparing figure 5 and figure 6, it is possible to observe that, when the movable portion 8 is in the fully extracted position, it extends mostly outside of the fixed portion 7, and that the distance between the movable portion 8 and the edge 5 of the lid 1 is maximal. For example, the movable portion 8 in the fully extracted position protrudes 180 mm from the fixed portion 7, or from the edge 5.

[0131] Instead, when the movable portion 8 is in the retracted position, it is mostly housed in the fixed portion 7 and the distance between the movable portion 8 and the edge 5 is minimal. For example, the movable portion in retracted position protrudes 55 mm from the fixed portion, or from the edge 5.

[0132] The resilient element 9 counteracts the displacement of the movable portion 8 in retracted position, by pushing it to the completely extracted position.

[0133] The movable portion 8 can assume a multiplicity of intermediate positions between the fully extracted position and the retracted position, in figure 7, for example, the movable portion 8 of the telescopic elements 6 is in an intermediate position between the extracted position and the retracted position.

[0134] In figure 7, for example, the movable portion 8 protrudes 130 mm from the fixed portion 7.

[0135] Returning to figure 1 , it is possible to observe that the telescopic rod 6 is connected to an air inflow line whose function will be described hereunder. In particular, the telescopic rod 6 preferably is in fluid communication with a chamber 11 of the air inflow line formed in the lid 1 , for example, just below the upper surface 3.

[0136] The fixed portion 7 has a first end 12 inserted into the body 2 of the lid 1 , and a second end 13 positioned at the edge 5.

[0137] The telescopic element 6 has a respective central hole 14 and 15 at the first end 12 and the second end 13.

[0138] In detail, at the first end 12, the telescopic element 6 has a bushing 16 extending along the longitudinal axis Y and precisely defining the central hole 14; instead, at the second end 13, the fixed portion 7 has a ring 17 jutting inward, i.e. toward the longitudinal axis Y, and defining the central hole 15.

[0139] As previously mentioned, the fixed portion 7 is hollow, i.e. has an inner cavity 18 extending along the longitudinal axis Y from the first end 12 to the second end 13.

[0140] The fixed portion 7, and in particular the inner cavity 18, is in fluid communication with the chamber 11 by means of the central hole 14, right at the first end 12.

[0141] As shown in figure 1 , the movable portion 8 is inserted into the fixed portion 7 through the central hole 15 of the second end 13.

[0142] Focusing the attention to the movable portion 8, it is possible to notice that it also extends along the longitudinal axis Y, actually being coaxial with the fixed portion 7, and has a first end 19 and a second end 20 opposite the first end.

[0143] The movable portion 8 preferably comprises a base 21 provided at the first end 19, a stem 22 extending from the base 21 and away from the first end 12 of the fixed portion 7, along the longitudinal axis Y. The second end 20 is actually on the stem 22, in the position opposite the base 21 .

[0144] Moreover, the base 21 has a lower end 21a and an upper end 21 b and a diameter greater than that of the stem 22.

[0145] For example, the diameter of the base 21 corresponds to the diameter of the inner cavity 18 of the fixed portion 7, i.e. it is 52 mm, while the diameter of the stem 22 is 48.3 mm.

[0146] As shown in figure 5, when the movable portion 8 is in the fully extracted position, it is in abutment on the ring 17 of the fixed portion 7 at the lower end 21a of the base 21.

[0147] As shown in figure 7, the movable portion 8 is also hollow, i.e. it has an inner cavity 23.

[0148] At the base 21 , the movable portion 8 has a flange 24 defining a central hole 26. It is possible to notice that the resilient element 9 is positioned, at one end, at the flange 24 of the movable portion 8 and at the bushing 16 of the fixed portion 7 on the other end, such as to actually counteract the displacement of the movable portion 8 to the retracted position in the fixed portion 7.

[0149] The central hole 26 of the movable portion 8 allows to put the inner cavity 23 of the movable portion 8 in fluid communication with the inner cavity 18 of the fixed portion 7 and, consequently, also with the chamber 11 of the air inflow line.

[0150] The air inflow line supplies air able to generate an air blade along the edge 5 of the lid 1. The air blade can be of the pressure or ventilated type. The pressure or ventilated air blade can possibly be enriched with sprayed water.

[0151] In figure 1 , it is actually possible to observe that the telescopic rod 6 preferably has a nozzle 29 formed in the movable portion 8. The nozzle 29 has the shape of a through slot, i.e. a through hole, in the wall of the telescopic rod 6 and extends parallel to the longitudinal axis Y. In particular, the nozzle 29 is formed in the wall of the movable portion 8. The nozzle 29 is provided in the telescopic rod 6, in a radial position such as to be facing the adjacent telescopic rod (not shown in figure 1 but which would be behind the telescopic rod 6 shown herein). In practice, the nozzle 29 is in front of the adjacent telescopic rod.

[0152] The nozzle can extend for 25 mm parallel to the longitudinal axis Y and has an angular width of 3 mm.

[0153] Figure 1 is a section considered with respect to a plane passing through the central axis X and dividing the telescopic rod 6 in half. It is therefore possible to imagine that the telescopic rod 6 also has one or more additional nozzles (precisely not visible in figure 1 ) provided in the movable portion 8, in the half opposite the one shown.

[0154] Actually, in the end opposite the end shown in figure 1 , the telescopic rod 6 preferably has two additional nozzles. This can be seen, for example, in figures 5-7, where it is possible to see the nozzles 29a, 29b extending parallel to the respective axis Y in the movable portion 8.

[0155] The nozzles 29, 29a and 29b can be seen as a whole in figure 4, which instead shows a section of a portion of the lid 1 considered along a plane tangential to the edge 5.

[0156] Figure 4 shows three telescopic rods 6 made identical but which, to make their respective identification easier, are denoted from left to right by the numbers of reference 6, 6a and 6b.

[0157] With reference to the telescopic rod 6, it is possible to observe the presence of the nozzle 29 described in figure 1 , and of two additional nozzles 29a and 29b provided in the movable portion 8 in an angular position opposite the nozzle 29 and at different heights with respect to it.

[0158] Considering the longitudinal axis Y, the nozzle 29 is actually at an intermediate height between the nozzle 29a and the nozzle 29b.

[0159] As mentioned above, the nozzles 29, 29a and 29b are provided in the movable portion 8 so as to face the adjacent telescopic rods.

[0160] The nozzles 29a and 29b of the telescopic rod 6 actually face the telescopic rod 6a and, similarly, the nozzles 29 and 29a, 29b of the telescopic rod 6a face, respectively, the telescopic rod 6 and 6b.

[0161] As denoted by the arrows 30, since the inner cavity 23 of the movable portion 8 is in fluid communication with the chamber 11 of the air inflow line, air generating an air blade directed along the edge 5, i.e. tangential with respect to the circular-shaped edge 5, comes out of the nozzles 29, 29a and 29b. In use, the pressurized air is heated.

[0162] The advantages of the presence of such nozzles will be discussed hereunder.

[0163] The movable portion 8 can have a hole 27 formed in a closing wall 28. The closing wall 28 can possibly be devoid of the hole 27.

[0164] Staying with figure 4, it is appropriate to highlight the advantage of providing each telescopic rod 6 extendable longitudinally, independently of the other telescopic rods.

[0165] As mentioned above, the lid 1 comprises a plurality of telescopic rods 6 and each telescopic rod 6 has a movable portion 8 movable longitudinally in a corresponding fixed portion 7 between a retracted position and a fully extracted position, and vice-versa, and is provided with a resilient element 9 which counteracts the movement of the movable portion in retracted position. When the lid 1 is not laid down on a ladle 200, the telescopic rods 6 are therefore all in the fully extracted position, as shown in figure 5. This can be the configuration of lid 1 , for example, before it is positioned on a corresponding ladle 200 in a preheating station.

[0166] From the moment the lid 1 is laid down on a ladle 200, the telescopic rods 6 adapt themselves, each independently of the others, to the surface of the edge 201 of the ladle 200 on which they go into abutment.

[0167] In practice, from the fully extracted position, each telescopic rod 6 is displaced to a specific intermediate position or a retracted position depending on irregularities present and encountered on the upper edge of the ladle, resulting in compression of the corresponding resilient elements 9.

[0168] As mentioned in the description of the known art, solidified slag of molten metal can actually be present on the upper edge 201 of the ladle 200, the upper edge 201 is therefore not homogeneous but can have solidified slag of molten metal of different height, extent and shape.

[0169] The fact that each telescopic rod 6 can extend longitudinally correspondingly to the presence or absence of a solidified slag of molten metal, and possibly to its height, allows the lid 1 to go into abutment on the ladle at several points, as many as the telescopic rods 6 are.

[0170] Once the preheating process of the ladle 200 has been completed, the lid 1 is raised and the ladle 200 is brought near the melting furnace. When the lid 1 is raised, it returns to the initial configuration, i.e. with all the telescopic rods in the fully extracted position due to the thrust exerted by the resilient element 9. The lid 1 is actually intended to be used for several work cycles and, when it will be positioned on another ladle or the same ladle after one or more additional work cycles, the telescopic elements 6 will therefore adapt themselves to the new shape of the surface of the upper edge of the ladle. For this reason, the lid 1 is versatile because, in addition to adapting itself to the irregular surface of the edge of a ladle, it can be adapted to the upper edge of several ladles.

[0171] The adaptability of the lid 1 can be better understood by taking figure 4 into consideration; in it, it is possible to observe that the telescopic rods 6, 6a, 6b extend, independently of the others, along the respective longitudinal axes Y, i.e. axially with respect to the central axis X of the lid 1. In other words, the longitudinal position assumed by each telescopic rod 6, 6a, 6b does not depend on the longitudinal position assumed by the other telescopic rods. In figure 4, the movable portion 8 of the telescopic rod 6 actually extends from the respective fixed portion 7 for a greater length with respect to the movable portion 8 of the telescopic rod 6a and with respect to the movable portion 8 of the telescopic rod 6b.

[0172] Each telescopic rod 6, 6a, 6b being extendable independently of the others, they can actually adapt their own longitudinal extent to the presence or absence of solidified slag of molten metal present on the upper edge 201 of the ladle 200 and, possibly, to the height of the slag itself.

[0173] As commented similarly above with reference to figure 10, the solidified slag of molten metal identified with the reference number 260 is of irregular shape, i.e. does not have a constant height but has various peaks. For example, the peak 261a has a greater height than the peaks 261 b and 261c.

[0174] Unlike what is described with reference to figure 10, where it was shown that a conventional lid rests with its edge exclusively on the highest peak, in figure 4, it is possible to observe that the lid 1 rests on the upper edge 201 of the ladle 200 or on the solidified slag present on the upper edge 201 of the ladle 200 by means of the telescopic rods 6, 6a, 6b.

[0175] The lid 1 is therefore not in abutment on the upper edge 201 of the ladle 200 at a single point, but at several points corresponding to the telescopic rods with which the lid 1 is equipped.

[0176] For example, always referring to figure 4, the rod 6 is in abutment on the peak 261c of the slag 260 of lesser height than the peaks 261a and 261 b. The rod 6 is in the fully extracted position and, in this circumstance, the movable portion 8 extends for 130 mm from the fixed portion 7.

[0177] Instead, the rod 6b rests on the peak 261a of greater height than the others. In this case, the rod 6b is in the retracted position and the movable portion 8 extends from the fixed portion for a lesser length, i.e. 75 mm for example.

[0178] Moreover, the rod 6a rests on the peak 261 b of intermediate height with respect to the peaks 261a and 26ac, and is therefore in an intermediate position between the extracted position and the retracted position.

[0179] The very presence of the same telescopic rods 6 allows to form a physical barrier which at least partially closes the space between the edge 5 of the lid 1 and the upper edge 201 of the ladle 200. In practice, the telescopic rods 6 delimit the escape of fumes and heat from the ladle during the preheating step of the ladle 200. Therefore, despite the presence or absence of an air blade generated by the nozzles of the stems, the lid 1 ensures that the dispersion of the heat from the space between the lid 1 and the ladle 200 during the preheating step is minimal and allows to use less energy, compared with conventional lids, to heat the ladle itself with the burner of the lid 1 (not shown).

[0180] A technician of the field will be able to arrange the telescopic rods such as to ensure the minimal possible fumes dispersion or heat loss.

[0181] For example, it is possible to arrange the telescopic rods circumferentially with respect to the axis X, in such a way that the longitudinal axes Y of two adjacent telescopic rods define among them, with respect to the central axis X, an angle of between approximately 6.55° and 14°.

[0182] The distance between two adjacent telescopic rods is preferably at most 150 mm, more preferably still at most 117.5 mm.

[0183] Energy savings increase if one or more nozzles 29, 29a, 29b, from which an air blade is generated, are provided. Such air blade allows to make an additional air barrier which prevents, or limits, the dispersion of fumes, and therefore heat loss, into the outer environment through the space delimited between the edge 5 of the lid 1 and the upper edge 201 of the ladle 200.

[0184] The fact of also making a hole 27 in the closing wall 28 can contribute to further limit the fumes dispersion and heat loss. Actually, in figure 4, it is shown, by arrows 30, that air, which allows to further limit the fumes dispersion and heat loss at the irregular surface of the edge of the ladle, also comes out of the hole 27 of the telescopic rods 6, 6a and 6b.

[0185] It is possible to make a lid 1 in which only some of the telescopic rods have one or more nozzles adapted to generate an air blade. In this case, the lid 1 could alternate one or more telescopic rods devoid of nozzles with one or more telescopic rods provided with one or more nozzles.

[0186] However, the lid 1 preferably comprises a plurality of telescopic rods 6 all provided with one or more nozzles adapted to generate an air blade.

[0187] A technician of the field will be able to form said one or more nozzles in the telescopic rods such as to make an air barrier and limit the fumes dispersion or heat loss.

[0188] For example, as described above, in the movable portion 8 of each telescopic rod, it is possible to make three nozzles 29, 29a and 29b shaped as elongated slots parallel to the longitudinal direction and arranged at different axial positions, i.e. at different heights, in the movable portion 8.

[0189] For the purpose of further reducing the dispersion of fumes, it is preferably possible to equip the lid 1 with a plurality of chains 32 attached to the lid 1 at an end of them.

[0190] In particular, in figure 1 , it is shown that the cover 1 has a supporting structure jutting radially away from the telescopic rod 6 and which is in a more outer radial position with respect to the telescopic rod 6 itself.

[0191] Two chains 32 are attached, at an end thereof, to the lid 1 at such supporting structure and extend downward beyond the upper edge 201 of the ladle 200. For example, the chains 32 have a length of 10 mm.

[0192] In figure 2, it is possible to observe that the lid 1 has a plurality of chains 32 arranged circumferentially with respect to the central axis X, in a more outer radial position with respect to the telescopic rods 6.

[0193] The chains 32 are also visible in the detail shown in figure 3.

[0194] With reference to figures 1-3, it is possible to see that, in a more inner radial position with respect to the telescopic rods 6, the lid 1 is preferably equipped with a ring 34 made of refractory material which protects the telescopic rods 6 from heat.

[0195] The ring 34 juts downward from the body 2 of the lid 1 and extends axially beyond the upper edge 201 of the ladle 1 for a greater length than the telescopic rods 6. For example, the ring 34 extends beyond the upper edge 201 of the ladle for a length of 275 mm.

[0196] Figures 2 and 3 actually show that the ring 34 run circumferentially around the lid 1 in a more inner radial position than that of the telescopic rods 6.

[0197] In the figures, the ring 34 is made in one piece: as an alternative, it is possible to equip the lid 1 with a plurality of panels or blocks of refractory material able to perform the same function as that of the ring 34.

[0198] Possibly, it is possible to provide a protective fiber pad positioned radially outside of the telescopic rods 6 and which allows the telescopic rods themselves to be protected.

[0199] Finally, the lid 1 can preferably comprise one or more bumper panels 35, shown in figure 1 , positioned in a more outer radial position with respect to the chains.

[0200] The bumper panels 35 can fully surround the lid 1 or protect only one part of the lid 1 .

[0201] For example, as shown in figure 2, the bumper panels 35 extend for 200° around the cover 1 and each bumper panel 35 identifies an angle of 20° with respect to the central axis.

[0202] Since the preferred embodiment described with reference to the accompanying figures corresponds to a lid 1 of a preheating station, the lid 1 equipped with a burner, not shown in the figures, is preferably provided at the central axis X. As known, the burner is used to keep the temperature high inside the ladle and to make sure that the refractory material covering the whole surface of the ladle 200 has the most uniform temperature as possible before the molten metal is poured into the ladle 200. Moreover, the lid 1 is preferably equipped with a device for recovering fumes generated inside the ladle by the burner.

[0203] The device for recovering fumes allows to convey fumes inside the ladle to the outside of the ladle.

[0204] A heat exchanger, arranged to recover some of the heat of the fumes sucked out through the device for recovering fumes and to transfer the heat recovered to the combustion air used by the burner, is preferably combined with the lid 1.

[0205] This way, some of the heat produced by the burner, which would otherwise be dispersed with the fumes outside of the lid 1 and the ladle, is recovered through the heat exchanger and used to reduce the amount of fuel (for example methane) required to heat the ladle to the desired temperature. This detail allows the burner to be lit at a lower intensity and / or for lesser duration, since the ladle can in part be heated through the energy recovered from the fumes.

[0206] According to estimates carried out by the Applicant, it was found that the lid 1 allows to significantly reduce the percentage of non-recovered fumes, i.e. allows to minimize the percentage of dispersed fumes that escape from the space defined between the edge of the ladle and the edge of the lid.

[0207] Limiting the dispersion of fumes allows to increase the amount of fumes recovered by the device for recovering fumes and, consequently, also the amount of heat recovered by the heat exchanger.

[0208] An estimate shows that the energy savings deriving from the use of the lid 1 is equal to 8-10%.

[0209] Such estimate was calculated, neglecting heat loss through the walls of the ladle, starting from the following formula relating to the thermal efficiency of an assembly constituted of a ladle and a lid provided with a burner: 100 Eff= efficiency

[0210] Ef = energy contained in the fumes;

[0211] Ec = energy provided with the fuel;

[0212] QfR = flow rate of recovered fumes (discharged via recovery system); cpR = specific heat of recovered fumes; dp = density of recovered fumes;

[0213] TR = temperature of recovered fumes;

[0214] QfNR = flow rate of NON-recovered fumes (lost due to an opening between shield and ladle);

[0215] CPNR = specific heat of NON-recovered fumes; dNR = density of NON-recovered fumes;

[0216] TNR = temperature of NON-recovered fumes;

[0217] Qc = fuel flow rate;

[0218] PCI = lower heating value of fuel

[0219] The energy efficiency of an assembly comprising a ladle and a lid according to the known art (EITRIF) and the energy efficiency of an assembly comprising a ladle and a lid 1 (EFFNEW) were calculated by using this formula.

[0220] These values were used to actually calculate the energy savings (S) relating to the use of a lid 1 equipped with a burner. The formula is the following:

[0221] A heat recovery system, combined with two preheating stations 36 and two preheating stations 39, is shown in figures 8 and 9. The preheating stations 36 extend along their own axis orthogonal to the ground (they are preheating stations of vertical type), whereas the preheating stations 39 extend along their own axis parallel to the ground (they are preheating stations of horizontal type). Each preheating station comprises a preheating machine 36a or 39a. In a known way, the preheating stations 36 are equipped with one or more arms 36b to which ends a lid 1 is attached, whereas the preheating stations 39 are equipped with one or more carriages 39b on which the lid 1 is positioned. In these figures, the lids 1 are positioned on corresponding ladles 200. The device for recovering fumes conveys the fumes, through a conduit 37, to a basket 38 or box arranged to contain scrap metals, such as to use the waste heat of the fumes to preheat them and use less energy to successively melt them.

[0222] The fumes in the conduit have a temperature of less than 300°C.

[0223] The fact that the preheating stations 36 and 39 convey the fumes to the same conduit 37 allows to constantly supply energy to the basket 38; this way, when one of the preheating stations is not operative, the others can actually be operative and supply energy to the basket 38.

Claims

CLAIMS1. A lid (1 , 1’, 1”, T”) for a ladle (200) comprising a body (2) which has a central axis (X) defining an axial direction, the body (2) being provided with an edge (5) at which, in use, the lid (1 , T, 1”, 1”’) is adapted to rest on an upper edge (201) of a ladle (200), in order to close said ladle (200), characterized by comprising a plurality of telescopic rods (6) perimetrically arranged at the edge (5) and jutting from the edge (5) along respective longitudinal axes (Y) parallel to the axial direction (X), each telescopic rod (6) being telescopically extendable, independently of the other telescopic rods (6), in a longitudinal position between, or equal to, a fully extracted position of the telescopic rod (6) from the lid (1 , T, 1”, 1”’) and a retracted position of the telescopic rod (6) in the lid (1 , 1’, 1”, 1”’), and wherein, in use, the longitudinal position of each telescopic rod (6) corresponds to the telescopic rod (6) in abutment against said upper edge (201 ) of a ladle (200) or against possible solidified slag of molten metal (261 ) present on said upper edge (201) of a ladle.

2. Lid (1 , 1’, 1”, 1”’) according to claim 1 , wherein one or more telescopic rods (6) are hollow and connected to an air inflow line (10) and wherein said one or more telescopic rods (6) each have one or more nozzles (29, 29a, 29b) facing one or both of the adjacent telescopic rods, said nozzles (29, 29a, 29b) being adapted, in use, to generate an air blade (30) along the edge (5) of the lid (1 , T, 1”, 1”’) by means of the inflow air.

3. Lid (1 , 1’, 1”, T”) according to claim 2, wherein said one or more nozzles (29, 29a, 29b) are arranged to generate a pressure air blade, or a ventilated air blade or some are adapted to generate a pressure air blade and others to generate a ventilated air blade.

4. Lid (1 , T, 1”, 1”’) according to claim 3, comprising one or more water spraying devices coupled to the air inflow line or coupled to the nozzles (29, 29a, 29b), said one or more spraying devices being configured to enrich the pressure air blade or the ventilated air blade with sprayed water.

5. Lid (1 , T, 1”, 1”’) according to any one of claims 1-4, wherein the telescopic rods (6) are circumferentially arranged on the edge (5) with respect to the central axis (X).

6. Lid (1 , T, 1”, T”) according to any one of claims 1-5, wherein the lid (1 , T, 1”, 1”’) comprises a lower surface (4) intended, in use, to face the ladle (200) and wherein said plurality of telescopic rods (6) jut from the lower surface (4) at the edge (5).

7. Lid (1 , T, 1”, T”) according to any one of claims 1-6, wherein each telescopic rod (6) comprises a fixed portion (7) integral with the lid (1 , T, 1”, 1”’) and provided with an inner cavity (18) extending along the corresponding longitudinal axis (Y), a movable portion (8) coaxially and telescopically inserted into the inner cavity (18) of the fixed portion (7) and a resilient element (9) arranged between an end of the fixed portion (7) and the movable portion (8), said resilient element (9) being configured to counteract the movement of the movable portion (8) toward the fixed portion (7).

8. Lid (1 , 1’, 1”, T”) according to claim 7, wherein the movable portion (8) is movable with respect to the fixed portion (7) between said fully extracted position, at which the distance between the movable portion (8) and the edge (5) is maximal, and said retracted position, at which the distance between the movable portion (8) and the edge (5) is minimal or null, and vice versa, and wherein the movable portion (8) can assume a multiplicity of intermediate positions between the fully extracted position and the retracted position.

9. Lid (1 , T, 1”, 1”’) according to claim 7 or claim 8, wherein the fixed portion (7) comprises a first end (12) inserted into the lid (1 , 1’, 1”, 1”’) and distal from the edge (5) and a second end (13), opposite the first end, positioned at the edge (5), wherein at least the second end (13) defines a central hole (15) into which the movable portion (8) is slidably inserted.

10. Lid (1 , 1’, 1”, T”) according to claim 9, wherein the second end (13) of the fixed portion (7) has a ring (17) jutting toward the respective longitudinal axis (Y) and defining said central hole (15), wherein the movable portion (8)comprises a base (21 ) and a stem (22) which juts from the base (21 ) and wherein the movable portion (8), in a fully extracted position, is in abutment on said ring (17) at the base (21).

11. Lid (1 , T, 1”, T”) according to claim 10, wherein the base (21 ) is constantly housed in the fixed portion (7), wherein the stem (22) has an end (20) opposite the base (21 ) and wherein the movable portion (8) is adapted to abut on said upper edge (201 ) of a ladle (200) or on solidified slag of molten metal (261) at said end (20) opposite the base (21 ).

12. Lid (1 , 1’, 1”, T”) according to claims 7-11 when dependent on claim 2, wherein said air inflow line (10) opens into the inner cavity (18) of the fixed portion (7), wherein also the movable portion (8) of said one or more telescopic rods (6) is hollow, i.e. it delimits an inner cavity (23) extending along the corresponding longitudinal axis (Y), and is in turn in fluid communication with the inner cavity (18) of the fixed portion (7), wherein said one or more nozzles (29, 29a, 29b) are provided in the moving portion (8) and, in use, are configured to generate an air blade (30) directed toward the adjacent rod (6).

13. Lid (1 , T, 1”, 1”’) according to claim 12, wherein the movable portion (8) of said one or more telescopic rods (6) has an end opposite the fixed portion (7) at which the movable portion (8) is adapted to abut on said upper edge (201 ) of a ladle (200) and wherein the movable portion (8) has at least one through hole (27), or a nozzle, provided at said end, at the longitudinal axis (Y), which, in use, is arranged to generate an air blade at said upper edge (201 ) or at a solidified slag of molten metal (261 ).

14. Lid (1 , 1’, 1”, 1”’) according to claims 1-13 when dependent on claim 2, wherein said one or more nozzles (29, 29a, 29b) extend parallel to the longitudinal axis (Y) for at least 9% of the length of the telescopic rod (6).

15. Lid (1 , 1’, 1”, 1”’) according to claims 3-14 when dependent on claim 2, wherein said one or more telescopic rods (6) each comprise two or more nozzles (29, 29a, 29b) provided, along the respective longitudinal axis (Y), at different heights and in alternately opposite angular positions.

16. Lid (1 , T, 1”, T”) according to claims 1-15, wherein an angle between 6.55° and 14°, between the longitudinal axes (Y) of two adjacent telescopic rods (6), is defined with respect to the central axis (X).

17. Lid (1 , T, 1”, 1”’) according to claims 1-16, comprising one or more chains (32) hanging from the lid (1 , T, 1”, 1”’) at said telescopic elements (6), or at some of them, in a more outward radial position, considering said central axis (X), with respect to the radial position of the telescopic elements (6).

18. Lid (1 , T, 1”, 1”’) according to claims 1-17, comprising one or more bumper plates (35) arranged around at least one portion of the edge (5) of the lid (1 , 1’, 1”, T”).

19. Lid (1 , T, 1”, T”) according to claims 1-18, comprising a ring (34), or one or more blocks, of refractory material in a more inward radial position, considering said central axis (X), with respect to the radial position of the telescopic elements (6).

20. Lid (1 , T, 1”, 1”’) according to claims 1-19, comprising a burner arranged to generate a flame adapted, in use, to heat the refractory material of a ladle (200) and / or comprising a device for recovering fumes generated, in use, inside a ladle (200).

21. Lid according to any one of the preceding claims, wherein the distance between two adjacent telescopic rods (6) is at most 150 mm, preferably at most 117.5 mm.

22. An assembly comprising a lid (1 , 1’, 1”, 1”’) according to one of the preceding claims and a preheating station (36) for a ladle (200) equipped with at least one arm (36b) or at least one carriage (39b) and wherein said lid (1 , T, 1”, 1”’) is constrained to said at least one arm (36b) or is positioned on said at least one carriage (39b), and wherein said lid (1 , T, 1”, 1”’) comprises a burner arranged to generate a flame adapted, in use, to heat the refractory material of a ladle (200) and / or comprises a device for recovering fumes generated, in use, by the burner.

23. A heat recovery system comprising a preheating station according toclaim 22, the heat recovery system also comprising:- a heat exchanger coupled to the recovery system of the fumes, which is arranged to recover part of the heat of the fumes recovered by said device for recovering fumes and to release said heat to the burner’s combustion air, and / or- at least one conduit (37) coupled to the device for recovering fumes, said at least one conduit (37) being adapted to be connected to a basket (38), or box, arranged to house scrap metals and to convey the recovered fumes to said basket (38), or box.

24. A method for limiting the amount of heat and / or fumes dispersed, in use, by a ladle (200), the method comprising the steps of: a) providing a lid (1 , T, 1”, 1”’) for a ladle (200) comprising a body (2) which has a central axis (X) defining an axial direction (X) and provided with an edge (5) at which, in use, the lid (1 , 1’, 1”, 1”’) is intended to rest on an upper edge (201) of a ladle (200), in order to close said ladle (200); b) laying down the lid (1 , 1’, 1”, 1”’) on a ladle (200) provided with an inner cavity (202) delimited by said upper edge (201 ) and adapted to accommodate molten metal, characterized in that the lid (1 , T, 1”, 1”’) comprises a plurality of telescopic rods (6) perimetrically arranged at the edge (5) and jutting from the edge (5) along respective longitudinal axes (Y) parallel to the axial direction (X), each telescopic rod (6) being telescopically extendable, independently of the others, in a longitudinal position between, or equal to, a fully extracted position of the telescopic rod (6) from the lid (1 , T, 1”, 1”’) and a retracted position of the telescopic rod (6) in the lid (1 , 1’, 1”, 1’”), in that at the end of step b), the lid (1 , T, 1”, 1’”) is positioned on the upper edge (201 ) of the ladle at its edge (5) and each telescopic rod extends along its own longitudinal axis (Y) for a length equal to the corresponding distance between the edge (5) of the lid and the upper edge (201 ) of the ladle orto the corresponding distance between the edge (5) of the lid and possible solidified slag of molten metal (260) present on said upper edge (201 ) of a ladle and in that said plurality of telescopic rods (6) limits, or prevents, the amount of heat and / or fumes dispersed, in use, by said ladle (200).

25. Method according to claim 24, wherein the distance between two adjacent telescopic rods (6) is at most 150 mm, preferably at most 117.5 mm.

26. Method according to claim 24 or 25, wherein during the step a) it is provided a preheating station (36) for a ladle (200) comprising said lid (1 , T, 1”, 1”’), said ladle (200) comprising in turn an inner cavity (202) coated by refractory material (203) and adapted to contain molten metal, wherein the lid (1 , 1’, 1”, 1”’) comprises in turn a burner and a device for recovering fumes generated by the burner and wherein the lid (1 , T, 1”, 1”’) is combined with a heat recovery system, wherein the method comprises a further step c) of:- activating the burner to preheat the refractory material (203) of the ladle (200) and activating the device for recovering fumes generated by the burner to recover the fumes generated by the burner in the ladle (200), wherein the heat of the fumes recovered by the system for recovering fumes is released, by means of the heat recovery system, to the combustion air used by the burner.

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