WO2021074937A1

WO2021074937A1 - Multiple casting apparatus and method

Info

Publication number: WO2021074937A1
Application number: PCT/IT2020/050244
Authority: WO
Inventors: Andrea De Luca; Massimiliano ISERA; Luca ENTESANO; Federico TORTUL
Original assignee: Danieli & C. Officine Meccaniche S.P.A.
Priority date: 2019-10-18
Filing date: 2020-10-06
Publication date: 2021-04-22
Also published as: IT201900019304A1; DE212020000746U1; CN219724531U

Abstract

Some embodiments described here concern a multiple casting apparatus (10), provided with two or more casting lines (11), which allows to cast metal materials enriched with different contents of alloy elements, a multi-line co- rolling plant (100), which allows to work two or more enriched metal materials on different co-rolling lines (103), and the corresponding methods.

Description

MULTIPLE CASTING APPARATUS AND METHOD

FIELD OF THE INVENTION

Embodiments described here concern a multiple casting apparatus that can be used in the steel industry to simultaneously cast two or more enriched metal materials, chemically differentiated from each other, starting from feeding, upstream of the casting, a single metal material low in alloy elements. The apparatus can be used in a multi-line co-rolling plant to simultaneously produce two or more finished products, chemically differentiated from each other, in particular, but not only, long products, for example bars, wire rod, beams or also other profiles, and/or flat products, for example sheet, strip, coil, or other profiles, starting from respective enriched metal materials.

BACKGROUND OF THE INVENTION

In the steel industry, methods and apparatuses are known, to process semi finished cast products, such as for example slabs, beam blanks, billets and blooms, with a square, rectangular or round section, or other shapes.

The semi-finished cast products, typically obtained by continuous casting of molten metal material, are subsequently processed by rolling, in order to obtain finished products, such as for example strip, bars, wire rod, beams or other profiles.

Steel plants for the production of long finished products are known, known as co-rolling plants, in which a rolling mill is directly connected to a casting apparatus, the latter comprising at least one mold, in a processing direction.

In particular, the rolling mill is located downstream of the casting apparatus, and can have a rolling line for example aligned and directly coupled with the casting line, thus defining a co-rolling line.

These known plants can perform a production process without any break in continuity, also known as “endless”, in which the semi-finished cast product is a single product, gripped, which extends from the solidification zone of the molten steel up to an entrance zone of the rolling mill and rolling occurs without any break in continuity of the casting.

Multi-line co-rolling plants and methods are known, for example described in patent document EP 3.052.259 B1 in the name of the present Applicant, in which the continuous casting apparatus is provided with at least two casting lines and the rolling mill downstream is provided with at least two rolling lines. Each casting line is aligned with a respective rolling line, defining altogether at least two co-rolling lines disposed side by side in respective processing directions, which can be parallel, both along the entire length and also only in certain segments, or diverging.

Document JP H02 137654 A concerns a method to control the introduction of a quantity of alloy in a tundish for the production of small bars in a continuous casting plant.

Document JP S6 1147953 A describes a method to cast the same molten steel by adding alloys by means of a tundish with a dividing tank.

Document JP H02 99251 A concerns a double casting equipment for the production of small bars in a continuous casting plant.

Document JP S59 169654 A describes a method to regulate the composition of molten metal which allows the economical production of small batches of steel materials with different composition by means of continuous casting.

Document US 7,618,582 B2 concerns a process to continuously refine steel by means of multiple distinct reaction channels using melting, oxidation, reduction and refining, for the continuous delivery of steel, for example, for a tundish of a continuous casting system.

These plants make it possible to differentiate the processing modes of the semi-finished cast products, so that, starting from a single casting apparatus, it is possible to simultaneously produce different sections of finished products, diversifying the operational configuration of the rolling lines.

For example, one line can be used for endless production, for example for the production of wire rod, while another can be used for the production of bars of a certain length and section, and yet another can be used to feed a further rolling mill.

It is also possible to obtain different final sizes, or different surface finishes, starting from the same casting apparatus.

However, different finished products often require different chemical composition specifications of the starting metal, for example different contents of alloy elements, also called alloying agents. The chemical composition of the steel with which the finished products are made is typically determined in the melting furnace and in the refining furnace.

One disadvantage of known multi-line co-rolling plants and methods is that in general, with known casting machines, it is not possible to diversify the chemical composition of the semi-finished cast products and, consequently, of the finished products, along the different co-rolling lines. Consequently, known casting machines can only cast semi-finished cast products that all have the same chemical composition of the steel, that is, having the same content of alloy elements for the different rolling lines in the casting step.

This disadvantage means that, if it is necessary to produce finished products that require different chemical composition specifications, it is necessary to produce them in batches, each with its own defined starting chemical composition, suitable to obtain only a certain type of products.

In particular, it is necessary to carry out a first processing sequence of a first finished product with a certain chemical composition, and then, at the end of the first processing sequence, to vary the chemical composition of the metal material coming from the melting area that feeds the casting apparatus and carry out the second processing sequence.

This solution entails not only long production times, but also an increase in the management and operating costs of the plants, which may not be exploited for all their production potential.

Furthermore, this solution makes the plants not very flexible to market demands, which may require the production of different finished products in a short time.

At most, if two finished products require different but compatible chemical specifications, it is possible to use the same composition for both products.

For example, using a steel with a suitable chemical composition for bars to produce construction rods, which require a chemical composition with fewer alloy elements than bars, a product with high characteristics, not all of which are necessary, would be obtained.

This solution, therefore, is not only applicable only in some cases but also has an economic disadvantage, since a material is enriched in a more complex and therefore more expensive way, to produce products for which such a wealth of elements is not required.

Some known solutions provide to enrich the metal material with alloy elements during the casting step, for example by means of a cored wire disposed directly inside the mold which, as it dissolves, releases the alloying agents into the flow of metal material.

However, these solutions have the disadvantage that the enrichment is carried out while the metal material flows through the mold and starts its solidification on the outside, therefore it is not possible to regulate the dissolving time of the alloying agents, which worsens the quality of the finished products. There is therefore a need to perfect a casting apparatus, to be used in multi-line rolling and/or co-rolling plants, and the corresponding methods, which can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to allow two or more finished products to be worked simultaneously even when said finished products require different chemical composition specifications, such as for example different contents of alloy elements.

It is therefore a purpose of the present invention to extend the applicability of known machines, plants and methods, to produce finished products of variable type and chemical composition simultaneously and in parallel. Another purpose of the present invention is to allow to effectively control the chemical composition of the finished products obtained by multi-line plants, guaranteeing high quality and preventing alloy elements intended for a finished product from contaminating another finished product being processed in the same plant. Another purpose of the present invention is to increase the productivity of known multi-line plants, allowing to increase the casting speed even when it is necessary to produce finished products with different contents of alloy elements.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes, the present invention concerns a multiple casting apparatus provided with two or more casting lines fed by a same feed receptacle, which overcomes the limits of the state of the art and eliminates the defects present therein.

The multiple casting apparatus comprises, as well as the feed receptacle, also one intermediate container and two or more molds associated with respective casting lines.

According to the present invention, the intermediate container is configured to divide a bath of molten metal material low in alloy elements present therein into at least two portions, at least one of which is associated with respective introduction means, configured to introduce alloy elements into the bath of metal material low in alloy elements.

In some embodiments, the at least two portions can be obtained by means of suitable diversion means, associated with the intermediate container, configured to divert the flow of molten metal material fed from the feed receptacle, so as to divide the bath of molten metal material into the at least two portions.

In some embodiments, the at least two portions can be obtained by means of suitable separation means, associated with the intermediate container, configured to physically divide the intermediate container into at least two parts, each part being associated with respective introduction means and with a respective portion of molten metal material.

In some embodiments, the intermediate container comprises a tundish, provided with two or more tanks to enrich, in an autonomous and independent manner between one tank and the other, the metal material low in alloy elements, obtaining respective enriched metal materials.

The two or more casting lines are therefore fed by respective enriched metal materials, chemically differentiated from each other.

In some embodiments, the intermediate container comprises outflow means suitable to discharge, along respective casting lines, the at least two portions of molten metal material in an independent and autonomous manner of one another.

In some embodiments, the feed receptacle comprises a ladle provided with discharge means suitable to discharge the metal material low in alloy elements into the intermediate container, for example into one or more of the two or more tanks.

In some embodiments, the multiple casting apparatus also comprises a control and management unit, to which at least the discharge means, the introduction means, the outflow means, and possible mixing means present are operatively connected and by which they are governed.

The control and management unit is configured to manage the functioning of the apparatus so as to enrich and cast the enriched metal materials, chemically differentiated from each other, in an autonomous and independent manner in the different casting lines.

Some embodiments described here also concern a multi-line co-rolling steel plant for the production of finished or semi-finished products, which comprises:

- the multiple casting apparatus described here, provided with two or more casting lines;

- a rolling mill, provided with two or more rolling lines, each associated with a respective casting line, thus defining respective co-rolling lines.

rolling plant can comprise sensors, operatively connected to the control and management unit, suitable to detect significant quantities of the materials being worked and to provide feedback to the control and management unit, in order to vary in real time the process parameters in a coordinated manner.

Other embodiments concern a multiple casting method, which provides to:

- feed molten metal material, low in alloy elements, from a feed receptacle to an intermediate container;

- divide the molten metal material in the intermediate container into at least two distinct portions;

- introduce alloy elements into at least one portion of the bath of molten metal material, in order to enrich the metal material low in alloy elements, in an autonomous and independent manner between one portion and the other, obtaining enriched metal materials, chemically differentiated from each other;

- cast along respective casting lines the portions of enriched metal materials, in an independent and autonomous manner between one portion and the other.

Other embodiments concern a method for multi-line co-rolling of two or more finished metal products, chemically differentiated from each other, which provides:

- multiple casting in accordance with the present description;

- multi-line rolling, wherein each of the enriched metal materials, chemically differentiated from each other, is rolled by means of a respective rolling line, in order to obtain the finished metal products, chemically differentiated from each other.

The present invention therefore allows to work in parallel semi-finished cast products which have different steel contents, cast from the same casting apparatus.

It is therefore possible to produce two or more finished products at the same time, even when these finished products require different chemical composition specifications, such as for example different contents of alloy elements, improving productivity compared to known multi-line plants.

Furthermore, the presence of the management and control unit and the sensors allows to effectively monitor the chemical composition of the finished products, regulating the process parameters in real time, thus allowing to limit, or also completely prevent, possible imperfections detected in the finished products, thus improving the quality of the production.

ILLUSTRATION OF THE DRAWINGS These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- figs. 1-4 are schematic representations of a multiple casting apparatus in accordance with some embodiments described here;

- fig. 5 is a detail of a portion of a casting apparatus;

- fig. 6 is a schematic representation of a multi-line co-rolling plant in accordance with some embodiments described here;

- fig. 7 is a schematic representation of a multiple casting apparatus in accordance with some embodiments described here;

- fig. 8 is a detail of fig. 7.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DESCRIPTION OF EMBODIMENTS

We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, one or more characteristics shown or described insomuch as they are part of one embodiment can be adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such modifications and variants.

Before describing these embodiments, we must also clarify that the present description is not limited in its application to details of the construction and disposition of the components as described in the following description using the attached drawings. The present description can provide other embodiments and non

phraseology and terminology used here is for the purposes of description only, and cannot be considered as limitative.

Some embodiments described by way of example by figs. 1-4 concern a multiple casting apparatus 10, configured to simultaneously cast, along respective

enriched metal materials, chemically differentiated from each other, starting from molten metal material low in alloy elements, that is, with a low content of alloy elements, also simply called poor metal material.

For example, poor metal material can be steel with a steel grade known as “GB/T 1499.2-2018 Grade HRB400/HRBF400”, low in manganese and with an absence of vanadium, while enriched metal materials can be steels known as “GB/T 1499.2-2018 Grade HRB400E/HRBF400E”, “GB/T 1499.2-2018 Grade HRB500”, “GB/T 1499.2-2018 Grade HRB500E/HRBF500E”, which have progressively higher contents of carbon, manganese, silicon and vanadium.

By way of example, in the attached drawings the poor metal material has been represented with a background of horizontal lines, while the two visible enriched metal materials have been represented with backgrounds of lines inclined in two different directions.

The apparatus 10 comprises a receptacle 12 to feed the molten metal material, an intermediate container 14 and two or more molds 37, associated with respective casting lines 11.

In some embodiments, the intermediate container 14 is configured to divide the bath of molten metal material, low in alloy elements, into at least two portions.

These two portions can be substantially associated with respective parts of the intermediate container 14, not necessarily physically separated from each other.

The intermediate container 14 can be of shapes suitable to promote the division of the bath into portions, for example, it can be elongated in a lateral direction, so that two bath portions can be located in correspondence with the lateral ends of the intermediate container 14.

Respective introduction means 15 are associated with each portion of the bath, in order to introduce alloy elements into the metal material low in alloy elements.

The introduction means 15 are therefore suitable to enrich each portion of poor metal material with alloy elements, chemically differentiating it into different metal materials enriched in an independent and autonomous manner from the other portions.

In some embodiments, the division of the bath of molten metal material into portions can be obtained by means of suitable dividing means 18, associated with the intermediate container 14.

In some embodiments schematically described by figs. 1-4, the dividing means 18 comprise separation means 218, configured to physically divide the intermediate container 14 into at least two parts, in each of which there is a portion of molten metal material, which can be enriched in an independent and autonomous manner from the other portions.

In some embodiments schematically described by figs. 7 and 8, the dividing means 18 comprise diversion means 118, associated with the intermediate container 14, configured to suitably divert the flow of molten metal material fed from the feed receptacle 12, so as to divide the bath of molten metal material into the at least two portions, which can be enriched in an independent and autonomous manner of one another.

In some embodiments, the feed receptacle 12 can for example comprise a ladle 112, suitable to contain and feed the poor metal material.

In some embodiments, the poor metal material can be obtained by means of melting carried out in a melting furnace, possibly an electric arc furnace, and then it can be poured into the ladle 112 in order to be refined by means of a ladle furnace.

In some embodiments, the refining can be set so as to supply the poor metal material with a base steel grade, which contains only the common alloy elements shared by each of the enriched metal materials that are to be cast in the different casting lines 11.

Further specific alloying agents, required for the enriched metal materials, cast from each casting line 11 , and for the corresponding finished products obtainable therefrom, will be added later, as described hereafter. In some embodiments, the ladle 112 can have, on a lower portion thereof, discharge means 13, suitable to discharge the molten metal material into the intermediate container 14, for example configured as a tundish 114.

The tundish 114 can be configured as a container of variable shape, made or lined with refractory material, which has one or more apertures in correspondence with an upper portion thereof, for the introduction of the poor metal material from the ladle 112.

The tundish 114 can provide outflow means 16, in correspondence with a lower portion thereof, suitable to cast, in a substantially vertical direction, the various enriched metal materials along the respective casting lines 11. The outflow means 16 can be suitable to cast the at least two portions of bath of molten metal material in an independent and autonomous manner of one another.

In some embodiments described by way of example by figs. 1-4, the tundish 114 comprises two or more tanks 17, for example separated by separation means 218, in this case configured as partitions, or barriers, made of refractory material, each suitable to contain the molten metal material.

In some embodiments, one or more tanks 17 can have some apertures in an upper portion thereof in order to receive the poor metal material cast from the ladle 112.

In some embodiments schematically described by fig. 5 and combinable with all the embodiments described here, on the bottom of the intermediate container 14, in particular of the tundish 114, there can be a stop well 19, configured to receive, during use, the impact of the jet of molten metal material coming from the ladle 112. This characteristic allows to reduce the wear of the materials with which the bottom of the tundish 114 is made and the maintenance costs of the apparatus 10, since the deteriorated stop well 19 can be replaced without replacing the entire tundish 114.

In some embodiments, two or more tanks 17 can be provided with the introduction means 15, in order to enrich the poor metal material in an autonomous and independent manner between one tank 17 and the other.

In some embodiments, two or more tanks 17 can be provided with the outflow means 16, in order to cast the enriched metal materials in an autonomous and independent manner between one tank 17 and the other.

In some embodiments, the tanks 17 can also have mixing means 20, to promote the mixing of the metal material with the alloy elements, preventing the creation of inclusions or concentration gradients of alloy elements in the enriched metal material, which can cause irregularities in the chemical composition of the finished products.

In some embodiments, the mixing means 20 can be configured as gas diffusers from which inert gas is blown into the tanks 17.

In some embodiments, the multiple casting apparatus 10 is provided with a control and management unit 21, suitable to monitor and manage the functioning of all the components of the apparatus 10.

In particular, the control and management unit 21 can manage the functioning at least of the discharge means 13, the introduction means 15, the outflow means 16 and the mixing means 20, in order to cast the enriched metal materials, chemically differentiated from each other, in an autonomous and independent manner in the various casting lines 11.

In the attached drawings, the hatching that connects the various components of the apparatus and the plant has only an explanatory function, and does not take into account the actual disposition of the circuits. It is therefore understood that even if, for ease of representation, multiple components may appear connected by the same hatching, we do not exclude the fact that the control and management unit 21 can manage these components separately from each other.

In some embodiments schematically described by fig. 1 , the discharge means 13 of the ladle 112 can comprise dischargers 22 associated with respective tanks 17 ofthe tundish 114.

During use, each discharger 22 can be partly immersed in the molten metal material present in the tundish 114, so as to prevent contact between the flow of molten metal material and air during discharge.

Each discharger 22 can be made of ceramic refractory material, perforated in a through manner along its longitudinal development, with a hole aligned with a respective discharger-gate 23 present on the bottom of the ladle 112, in order to define a passage channel for the flow of molten metal material.

In some embodiments, with each discharger 22 there can be associated a ladle- slide 24, configured to be moved by the control and management unit 21 from an open position to a closed position, in order to respectively allow and block the discharge flow of molten metal material from the ladle 112.

For example, the ladle-slide 24 can comprise a fixed perforated plate and a mobile perforated plate, the latter mobile between the open position, in which the hole is aligned with the passage channel, to the closed position, in which the hole is offset from the passage channel.

In some embodiments, the outflow means 16 of the tundish 114 can provide dischargers 122, associated with respective discharger-gates 123 present on the bottom of the tanks 17 from which the enriched metal materials are cast along the respective casting lines 11, for example along a first 11a and a second casting line lib.

Again with reference to fig. 1, the outflow means 16 can provide means 25 for regulating the flow, configured to be moved by the control and management unit 21 in order to regulate the casting speed of the enriched metal material from the respective tank 17 of the tundish 114, in an autonomous and independent manner from the other tanks 17.

In some embodiments schematically shown in fig. 1 , with particular reference to the tank 17 on the left, the means 25 for regulating the flow can be configured as a tundish-slide 26, which can for example comprise two fixed perforated plates 27 and a mobile perforated plate 28, provided with holes with sizes coherent with the passage channel, and a command module 29, operatively connected to the control and management unit 21.

The fixed perforated plates 27 are mounted with the hole aligned with the passage channel.

The mobile perforated plate 28 can be moved by the control and management unit 21, by means of the command module 29, in an adjustable manner from an open position to a closed position. In the open position, the hole of the mobile perforated plate 28 is aligned with the passage channel; in the closed position, the hole of the mobile perforated plate 28 is offset with respect to the passage channel; in the intermediate positions, the hole of the mobile perforated plate 28 is partly aligned with the passage channel, providing a variable passage gap which allows to regulate the casting speed.

In some embodiments schematically shown in fig. 1 , with particular reference to the tank 17 on the right, the means 25 for regulating the flow can provide a buffer rod 30, or stopper, which has a tip of sizes coherent with the hole of the discharger-gate 123 of the tank 17, vertically movable by the control and management unit 21 in order to vary the occlusion thereof, thus regulating the casting speed.

In some embodiments schematically shown in fig. 1, with particular reference to the tank 17 on the left, the introduction means 15 can comprise nozzles, or lances 31, partly immersed in the molten metal material, by means of which the alloy elements can be removed from special tanks (not shown) and delivered into the tanks 17 of the tundish 114, for example in powder form, in order to enrich the poor metal material.

For example, it is possible to deliver alloy elements such as Vanadium to enrich the poor metal material in one or more specific and desired tanks 17.

Vanadium can be supplied as Fe-V in powder form by means of a nozzle, or lance 31.

In possible variants, the Fe-V can be supplied by a nozzle, or lance 31, of the “ejector argon” type.

The lances 31 can be operatively connected to the control and management unit 21, which for example can regulate the delivery position and depth, the flow rate of the alloy elements, the tank from which the alloy elements, possibly of different types, are taken and other parameters.

In some embodiments schematically shown in fig. 1, with particular reference to the tank 17 on the right, the introduction means 15 can comprise one or more cored wires 32, possibly unwound from a reel 33 at a predetermined immersion speed, of the order of a few meters per second, which depends on the desired delivery depth.

The reel 33 can be unwound by means of a rotary actuator operatively connected with the control and management unit 21, which can therefore regulate the immersion speed and depth.

The cored wire 32 can be a flexible tube made of metal material, for example steel, internally hollow and of reduced thickness, inside which there are alloy elements in powder form.

When the cored wire 32 comes into contact with the molten metal material, the metal material with which it is made begins to melt, gradually releasing the alloy

In s -ome e -mbod -iments described bv wav of examnle bv fie. 2. the discharee means 13 of the ladle 112 can comprise a single discharger 22, provided with two or more discharge branches 34a, 34b, each associated with a respective tank 17 of the tundish 114.

In these embodiments, the discharger 22 can also provide, as an alternative or in addition to the ladle-slide 24, a three (or more) way valve 35, of a type suitable for iron and steel use, disposed at the fork of the discharge branches 34a, 34b and operatively connected to the control and management unit 21, which can therefore allow the flow of molten metal material through all the discharge branches 34a, 34b, or only part of them.

In some embodiments described by way of example by fig. 3, the ladle 112 is a mobile ladle, by means of known movement means 36 operatively connected to the control and management unit 21, in order to alternatively discharge the molten metal material into one of the tanks 17 of the tundish 114.

In these embodiments, the terminal end of the discharger 22 associated with the ladle 112 can be located at a greater height than the height of the separation means 218 that separate the tanks 17 of the tundish 114, so as not to interfere with the horizontal movement of the ladle 112.

Some embodiments are also possible in which the ladle 112 is mobile both horizontally and also vertically, so as to be able to immerse the terminal end of the discharger 22 into the molten metal material in the tundish 114 during discharge, preventing contact with air.

In these embodiments, it is also possible to lift the ladle 112 during the horizontal movement, so as to prevent interference between the end of the discharger 22 and the separation means 218 of the tanks 17.

In some embodiments schematically described by fig. 3, with one tank 17 of the tundish 114, in particular with the tank 17 on the right, there can be associated several casting lines 11, for example a second 1 lb and a third casting line 11c, providing respective outflow means 16, which can operate in an autonomous and independent manner of one another. These embodiments are particularly advantageous since they allow to work the semi-finished cast products in an autonomous and independent manner, in order to obtain both finished products that have the same chemical composition, similarly to what is disclosed in patent document EP 3,052,259 B1 in the name of the same Applicant, and also finished products that have different steel compositions, in accordance with the embodiments described here.

In some embodiments described by way of example by fig. 4, the tundish 114 comprises a plurality of tanks 17, in particular five tanks 17, of which:

- a central tank 17a suitable to receive the molten metal material from the ladle 112, which can possibly have the stop well 19;

- two intermediate tanks 17b, 17c, adjacent to the central tank 17a, suitable for the enrichment of the poor metal material, having the introduction means 15 and, possibly, also the mixing means 20;

- two external tanks 17d, 17e, adjacent to the intermediate tanks 17b, 17c, suitable to cast the enriched metal materials, having the outflow means 16.

In these embodiments, the separation means 218 can be at a lower height than the height of the walls of the tundish 114, so that, during use, the molten metal material can flow into the intermediate tanks 17b, 17c and into the external tanks 17d, 17e, once the central tank 17a and the intermediate tanks 17b, 17c respectively have been filled, as schematically indicated by the arrows in fig. 4.

It is obvious to the person of skill in the art that some embodiments (not shown) are also possible which provide more than one central tank 17a, for the discharge of the molten metal material and/or more than two intermediate tanks 17b, 17c, for the enrichment of the molten metal material and/or more than two external tanks 17d, 17e for the casting of the molten metal material.

For example, it is possible to provide two more internal intermediate tanks 17b, 17c, adjacent to the central tank 17a, which enrich and cast the molten metal material with a certain content of alloying agents, and two more external intermediate tanks 17b, 17c, adjacent to the more internal intermediate tanks 17b, 17c, which further enrich the molten metal material and cast respective enriched metal materials with a higher content of alloying agents or with other alloying agents of a different type.

Advantageously, the embodiments in which the enrichment and casting are performed in separate tanks 17 allow to improve the quality of the finished products by increasing the mixing and dissolution time of the alloying agents in the molten metal material. It is therefore possible to obtain finished products with a more uniform chemical composition, compared to the embodiments in which the metal material is poured, enriched, mixed and simultaneously cast in the same tank 17.

In some embodiments schematically described by figs. 7 and 8, the primary flow F0 of molten metal material arriving from the ladle 112 can be diverted by the diversion means 118 in two or more different directions, that is, into two or more secondary flows FI, F2.

In some embodiments, the diversion means 118 can comprise depressions, rises, obstacles, recesses, indentations, protrusions, edges, cantilevered profiles conformed in a variable manner, roughness, protuberances, wedges, partitions, barriers, or any other element or profile whatsoever suitable to divert and separate a flow into different flows.

For example, in some embodiments not shown, diversion means 118 can be provided in the zone in which the primary flow F0 impacts against the bottom of the intermediate container 14.

In these embodiments, the diversion means 118 can comprise wedge-shaped or laminar protrusions, or channels, or depressions, or reliefs, defined on the bottom of the intermediate container 14, which separate the primary flow F0 into two or more secondary flows FI, F2, directed in different directions, that is, toward different parts of the intermediate container 14.

In some embodiments schematically described by figs. 7 and 8, the diversion means 118 can comprise obstacles, for example partitions or barriers, of a height lower than the height of the walls of the intermediate container 14, which divert the primary flow F0 into a first secondary flow FI, which remains confined in the proximity of the discharge zone and re-mixes with the material fed by the primary flow F0, and a second secondary flow F2, able to go past the diversion means 118 from above.

The Applicant has verified that, once the first FI and the second secondary flow F2 are separated, vortexes are created in the zone of separation between the two flows FI, F2 which prevent them from re-mixing, as schematically shown in fig. 8.

This phenomenon can be explained, by way of example, by observing that in the zone in the proximity of the diversion means 118 the flow lines of the first FI and of the second secondary flow F2 are opposite and diverging from each other, as indicated by the arrows.

This phenomenon can be further explained by considering that the second secondary flow F2 has to go past, from above, both the obstacle posed by the diversion means 118 and also the vortexes of the first secondary flow FI. Once the second secondary flow F2 impacts against the wall of the tundish 114, a return flow is created, directed toward the diversion means 118, necessarily from below. This return flow will impact against the diversion means 118 and will reinforce the vortexes in a divergent and opposite direction with respect to the vortexes of the first secondary flow FI.

The diversion means 118 therefore prevent the return flow of the second secondary flow F2 from re-mixing with the material fed by the primary flow F0 arriving from the ladle 112, effectively dividing the bath of molten metal material in the intermediate container 14 into two distinct portions which do not mix together, and which can be enriched and cast in an independent and autonomous manner, respectively by introduction means 15 and outflow means 16. In these embodiments, the molten metal material can be fed into the tundish 14 at a speed suitable to generate and promote the vortexes and the separation of the flows.

In some embodiments, each casting line 11 of the multiple casting apparatus 10 can comprise, downstream of the tundish 114, a mold 37 (schematically shown in figs. 1-4 and 6), a straightening unit 38 (schematically shown in fig. 6 and, partly, in figs. 1-4) and an emergency oxy-fuel cutting unit 39 (schematically shown in fig. 6), which are known and are associated with the respective outflow means 16.

The straightening unit 38 can be provided with rollers configured to straighten the cast product from a substantially vertical casting direction to a substantially horizontal rolling direction.

Some embodiments described here also concern a multi-line co-rolling steel plant 100 for the production of finished products, in particular long metal products.

In accordance with the present description, the plant 100 is configured to carry out the solidification of metal, for example liquid steel, into semi-finished cast products and to produce finished products starting from such semi-finished cast products.

The semi-finished cast products can be blooms or billets with a circular, rectangular, square or polygonal section, typically used for the production of bars, round pieces, rod, profiles, or they can also be beam-blank with a substantially H-shaped section for the production of beams or profiles.

In some embodiments schematically described by fig. 6, the plant 100 comprises a multiple casting apparatus 10 in accordance with the present description, which comprises two or more casting lines 11, and a rolling mill 101, which comprises two or more rolling lines 102, each associated with a respective casting line 11, thus defining respective co-rolling lines 103.

In accordance with the present description, with the expression “co-rolling line” we therefore mean that a casting line 11 is aligned, that is, it is on the same axis, with respect to the respective rolling line 102 downstream, or at least with respect to an initial segment of the rolling line 102, therefore without the provision of intermediate devices, transfer devices, shuttles, translating planes, mobile roller ways, or other, which actively move the cast metal, for example translating it in directions transverse to a direction of advancement and work.

In this way, it is possible to create a work process without a break in continuity, or endless, from the casting of the liquid steel to obtaining the finished products. In the endless process, with the expression “semi-finished cast product” we mean a single billet, having a length that spans from the solidification zone of the casting apparatus 10 to the entrance of the rolling mill 101.

The machine radius, that is, the radius of curvature of the casting line, can have a value comprised between 5 m and 20 m, preferably between 7 m and 18 m.

The steel plant 100 is also suitable to carry out a discontinuous work process, that is, in which the feed of the semi-finished cast products to the rolling mill 101 occurs with a partial break in continuity. In the discontinuous process, the rolling mill 101 is fed with segments of desired length, for example comprised between 12 m and 80 m.

In some embodiments schematically described by fig. 6, the plant 100 can have a layout comprising a single tundish 114 from which a first 11a and a second casting line lib branch off, associated respectively with a first 102a and a second rolling line 102b, in order to define co-rolling lines 103, in particular one line for rod 103a and one line for bars 103b.

For example, the line for bars 103b can have a heating furnace 104, preferably of the induction type, disposed immediately downstream of the multiple casting apparatus 10.

Downstream of the heating furnace 104 there can be two rolling trains 105, in particular a roughing train 105a and an intermediate rolling train 105b, which can be followed by a cooling unit 106, for example of the waterbox type, downstream of which a further rolling train 105 is disposed, in particular a finishing train 105c.

In some embodiments, the line for bars 103 b continues with another cooling unit 106 and a brake-shear unit 107, to cut the bars to commercial size.

In some embodiments, the line for bars 103b can then end with a unit 108 for storing bars and creating bundles. The bundles of bars can be unloaded by means of a suitable plate 109 for unloading bundles of bars.

For example, the line for rod 103a can have a heating furnace 104, preferably of the induction type, disposed immediately downstream of the multiple casting apparatus 10, followed by three rolling trains 105, in particular a roughing train 105a, an intermediate rolling train 105b and a finishing train 105c.

The line for rod 103 a can then provide a cooling unit 106 followed by another rolling train 105, in particular a fast rolling train 105d, followed by another cooling unit 106 and a coil forming unit 110.

In particular, the coil forming unit 110 can provide a coil forming head, a rod belt and a coil collection well.

It is obvious to the person of skill in the art that a multiple casting apparatus 10 made in accordance with the embodiments described here can also be used, without particular difficulties and by means of obvious adaptations, in a steel plant based on semi-continuous casting. In such cases, in fact, it is sufficient, for example, to couple molds to the outflow means 16 of the tundish 114, thus achieving the possibility of simultaneously working metal products that are chemically differentiated from each other.

In possible variants, the mold can be of the power mold type. The mold can possibly have an at least partly curved longitudinal development.

In some embodiments, the apparatus 10 and the plant 100 of the present invention can provide sensors S, operatively connected to the control and management unit 21, suitable to detect significant quantities of the materials being worked, providing feedback to the control and management unit 21, in order to vary in real time the process parameters in a coordinated manner.

In particular, the control and management unit 21 can vary the process parameters in feed-forward and/or feedback mode, as described below.

In some embodiments, the sensors S can be of the thermal, optical, radar, capacitive, laser, Eddy current type.

In some embodiments, sensors based on spectroscopic methods can be employed, such as for example infrared spectroscopy, UV- Visible spectroscopy, both in emission and also in absorption, LIBS (Laser Induced Breakdown Spectroscopy), also known as LIPS (Laser Induced Plasma Spectroscopy). In some embodiments, the sensors S can be configured to detect the surface temperature of a material, for example they can be infrared sensors or sensors of any other suitable type whatsoever.

In some embodiments, the sensors S can be configured to detect the microcrystalline structure of a material.

In some embodiments, the sensors S, for example those based on LIBS, can be configured to detect the chemical composition of a material, in particular the content of alloy elements.

The functioning of the LIBS type sensors S provides to irradiate the metal material with a laser pulse, which vaporizes a portion of its mass, for example comprised between picograms and nanograms, taking it to the plasma state; the sensor S, by detecting the radiation emitted by the plasma, in particular by the chemical elements that constitute the metal material present in atomic or ionized form in the plasma, can trace the chemical composition of the starting metal material.

Advantageously, this type of sensors can therefore be used to analyze materials in any state whatsoever, for example liquid, molten, solid, partly solid, both crystalline as well as glassy or metallic, since, regardless of the state that the material starts from, the analysis is performed on the plasma generated by means of laser irradiation.

Such sensors S can therefore be used to analyze the bath of molten metal material, as well as to analyze the semi-finished cast products, and also to analyze the finished products.

Furthermore, it is possible, with a single sensor device, to analyze the plasma emission in different regions of the electromagnetic spectrum, for example UV and IR, by means of one or more suitable detectors.

Advantageously, the LIBS type sensor S, equipped with a detector in the infrared spectrum, can also detect the temperature of the metal material.

Advantageously, LIBS type sensors S can be associated and operatively coordinated, for example by the control and management unit 21, with mixing means 20 configured as gas diffusers. In these embodiments, the laser pulse can be directed inside an inert gas bubble blown into the bath of metal material in the tanks 17. This characteristic allows to measure the chemical composition and temperature of the bath in a continuous and reliable manner.

In some embodiments, sensors S provided in the proximity of the tanks 17 of the tundish 114, schematically shown in figs. 1-4, can detect and communicate to the control and management unit 21 the chemical composition, in particular the content of alloy elements, and/or the temperature of the baths of enriched metal material in the tanks 17. The control and management unit 21 can, on the basis of such data, regulate in an independent and autonomous manner for each tank 17 the work parameters of the introduction means 15 and/or of the mixing means 20.

For example, the flow of alloying agents exiting the lances 31 can be increased in the event that an excessively low content is detected in the enriched metal material.

In some embodiments, sensors S provided downstream of the casting lines 11 , immediately after the oxy-fuel cutting unit 39, schematically shown in fig. 6, can detect and communicate to the control and management unit 21 the chemical composition, in particular the content of alloy elements, and/or the microcrystalline structure and or the temperature of the semi-finished cast products entering the rolling mill 101. The control and management unit 21 can, on the basis of such data, regulate in an independent and autonomous manner for each casting line 11 the work parameters of the introduction means 15, of the mixing means 20 and or of the outflow means 16.

For example, the flow of inert gas can be increased to further promote the dissolution of the alloy elements, in the event that inclusions or concentration gradients of alloying agents are detected in the semi-finished cast products.

In some embodiments, sensors S provided downstream of the rolling lines 102, immediately after the last cooling units 106, can communicate to the control and management unit 21 the chemical composition, in particular the content of alloy elements, and/or the microcrystalline structure of the finished products exiting the rolling mill 101. The control and management unit 21 can, on the basis of such data, regulate in an independent and autonomous manner for each co-rolling line 103 the work parameters of the plant 100, for example of the introduction means 15 or of the heating furnaces 104.

For example, the temperature of the heating furnaces 104 can be increased, in the event that rolling defects are detected due to inclusions or to metal material that has solidified too quickly.

Advantageously, the present invention allows to control and manage the different tanks 17 of the tundish 114, the different casting lines 11, the different co-rolling lines 103 in an autonomous and independent manner with respect to each other.

It is therefore possible to perform a closed loop process control, in feedback, by setting some set point values, for example for the chemical composition and/or temperature of the bath or of the semi-finished cast products, which are compared with the values actually detected by the sensors S. On the basis of the outcome of the comparison, the control and management unit 21 can modify the work parameters of the apparatus 10 and/or of the plant 100 in such a way as to reduce the difference between the detected values and the set points.

Advantageously, the apparatus 10 and the plant 100 are therefore able to autonomously modify, without the external intervention of operators, the production procedures, adapting them to the detections of the S sensors.

For example, in some embodiments there can be provided sensors S associated with the central tank 17a, which detect the chemical composition of the poor metal material arriving in the tundish 114, and sensors associated with the external tanks 17d, 17e, which detect the chemical composition of the enriched metal materials being cast, and the set point values can be desired contents for the alloying agents of the cast materials. In these embodiments, the control and management unit 21 can regulate the in-flow of alloying agents into the intermediate tanks 17b, 17c, or the dissolution time, in order to minimize the difference between the contents of the cast materials and the set points. Some embodiments described here also concern a multiple casting method, on two or more casting lines 11 , which initially provides to feed the metal material low in alloy elements from a feed receptacle 12 to an intermediate container 14.

The method also provides to divide the bath of molten metal into at least two portions. In some embodiments, this division can be obtained by providing that the intermediate container 14 is physically divided, for example by means of separation means 218, into at least two parts, each part being associated with a respective portion of the molten metal material. In these embodiments, the division can be associated with the feed, since the individual parts of the intermediate container 14 can be fed, effectively dividing the bath.

In some embodiments, the division can be obtained by providing suitable diversion means 118, which divide the flow of metal material arriving from the feed receptacle 12 into at least two portions.

In these embodiments, the molten metal material can be fed at a speed suitable to generate and promote the division of the bath by means of suitable vortexes.

Subsequently, the alloy elements can be introduced into the different portions, in an autonomous and independent manner between one portion and the other, in order to obtain different enriched metal materials, chemically differentiated from each other.

These enriched metal materials can be cast, in an independent and autonomous manner between one portion and another.

In some embodiments, the feed, the introduction of the alloying agents and the casting can be performed simultaneously in the different parts of the intermediate container 14 or for the different portions of molten metal material.

Alternative embodiments can also provide that these operations are performed at different times between one part and the other, or between one portion and the other.

For example, in the event the intermediate container 14 is configured as a tundish 114 provided with three tanks 17, it is possible to feed one tank 17 with the poor metal material, while the alloying agents are introduced and mixed in a different tank 17 and the enriched metal material is cast from the last tank 17, carrying out the different steps of the method in a staggered sequence between the three tanks 17.

According to another example, it is possible to feed the tanks 17 only when necessary. In particular, in the event several casting lines 11 work at different casting speeds, for example because they are associated with finished products of different types, these are emptied at non-synchronized times. In such cases it is possible to supply the tanks 17 with poor metal material when the level of the bath falls below a certain predetermined threshold, guaranteeing the continuity of the work process. Some embodiments described here also concern a method for multi-line co rolling of two or more finished metal products, chemically differentiated from each other, which provides to use the multiple casting method described here to cast different enriched metal materials and roll them by means of multi-line rolling, wherein several rolling lines 102 are associated with respective casting lines 11.

It is clear that modifications and/or additions of parts or steps may be made to the apparatus 10, to the plant 100 and to the method as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of apparatus 10, plant 100 or method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

In particular, it will be obvious to a person of skill in the art that it is possible to provide an arbitrary number of tanks 17, casting lines 11 and co-rolling lines 103.

For example, by combining the embodiments described by way of example by fig. 1, or 2, or 3, with the embodiments described by fig. 4, it is possible to produce an apparatus 10 that comprises a tundish 114 with five tanks 17, all provided with introduction means 15 and outflow means 16, a ladle 112 suitable to feed these five tanks 17, and five molds 37, with which five co-rolling lines 103 can be associated.

In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.

Claims

1. Multiple casting apparatus, comprising at least one receptacle (12) to feed the molten metal material, one intermediate container (14) and two or more molds (37) associated with respective casting lines (11), characterized in that said intermediate container (14) is configured to divide a bath of molten metal material, low in alloy elements, present in said intermediate container (14), into at least two portions, at least one of said two portions being associated with respective introduction means (15), to introduce alloy elements into said bath of metal material low in alloy elements.

2. Apparatus as in claim 1, characterized in that it comprises diversion means (118), associated with said intermediate container (14), configured to divert the flow of molten metal material fed from said feed receptacle (12), so as to divide said bath of molten metal material into said at least two portions.

3. Apparatus as in claim 1, characterized in that it comprises separation means (218), associated with said intermediate container (14), configured to physically divide said intermediate container (14) into at least two parts, each part being associated with respective introduction means (15) and with a respective portion of molten metal material.

4. Apparatus as in claim 3, characterized in that said intermediate container (14) comprises a tundish (114) provided with two or more tanks (17) in order to enrich, in an autonomous and independent manner between one tank (17) and the other, said metal material low in alloy elements, obtaining respective enriched metal materials.

5. Apparatus as in any claim hereinbefore, characterized in that said intermediate container (14) comprises outflow means (16) suitable to cast said at least two portions of bath of molten metal material in an independent and autonomous manner of one another, along respective casting lines (11).

6. Apparatus as in claim 4 or 5, characterized in that said feed receptacle (12) comprises a ladle (112), provided with discharge means (13) suitable to discharge said metal material low in alloy elements into one or more of said two or more tanks (17).

7. Apparatus as in claim 6, characterized in that at least one of said two or more tanks (17) affected by the discharge of the metal material low in alloy elements from said ladle (112), has a stop well (19) configured to receive, during use, the impact of the jet of metal material coming from the ladle (112).

8. Apparatus as in claim 6 or 7, characterized in that said discharge means (13) comprise two or more dischargers (22), each associated with a respective tank (17).

9. Apparatus as in claim 6 or 7, characterized in that said discharge means (13) comprise a discharger (22), provided with two or more discharge branches (34a, 34b), each associated with a respective tank (17).

10. Apparatus as in claims from 6 to 9, characterized in that said ladle (112) is a mobile ladle, configured to alternately discharge said metal material low in alloy elements into one of said two or more tanks (17) of the tundish (114).

11. Apparatus as in any claim from 6 to 10, characterized in that said tundish (114) comprises five tanks (17), of which:

- a central tank (17a), configured to receive said metal material low in alloy elements from said ladle (112);

- two intermediate tanks (17b, 17c), provided with respective introduction means

(15);

- two external tanks (17d, 17e), provided with respective outflow means (16).

12. Apparatus as in any claim from 6 to 11, characterized in that it comprises a control and management unit (21), to which at least said discharge means (13), said introduction means (15) and said outflow means (16) are operatively connected and by which they are governed, configured to manage the functioning of the apparatus (10) so as to enrich and cast the enriched metal materials, chemically differentiated from each other, in an autonomous and independent manner in the different casting lines (11).

13. Apparatus as in claim 12, characterized in that it comprises sensors (S), operatively connected to the control and management unit (21), suitable to detect significant quantities of the materials being worked and provide feedback to the control and management unit (21), in order to vary in real time the process parameters in a coordinated manner.

14. Apparatus as in claim 13, characterized in that it comprises sensors (S) associated with the two or more tanks (17) and suitable to detect and communicate to the control and management unit (21) the contents of alloy elements of the respective baths of enriched metal material, and in that the control and management unit (21), on the basis of said contents of alloy elements detected, regulates, in an independent and autonomous manner between one tank (17) and the other, the work parameters of the introduction means (15).

15. Apparatus as in claims 13 or 14, characterized in that said sensors (S) are based on LIBS (Laser Induced Breakdown Spectroscopy).

16. Multi-line co-rolling steel plant for the production of finished metal products, characterized in that it comprises:

- a multiple casting apparatus (10) as in any claim hereinbefore, provided with two or more casting lines (11);

- a rolling mill (101), provided with two or more rolling lines (102), each associated with a respective casting line (11), thus defining respective co-rolling lines (103).

17. Plant as in claim 16, characterized in that at least one of said co-rolling lines (103) is an endless type line.

18. Plant as in claim 16 or 17, characterized in that at least one of said co rolling lines (103) is a discontinuous type line.

19. Plant as in any claim from 16 to 18, characterized in that it comprises a single tundish (114) from which two co-rolling lines (103) branch out, in particular one line for bars (103a) and one line for rod (103b).

20. Plant as in any claim from 16 to 19, characterized in that it comprises sensors (S) disposed downstream of each of the two or more casting lines (11) and upstream of the respective two or more rolling lines (102), suitable to detect and communicate to a control and management unit (21) the contents of alloy elements of the respective semi-finished cast products, and in that the control and management unit (21), on the basis of said contents of alloy elements detected, regulates, in an independent and autonomous manner between one casting line (11) and the other, the work parameters of the introduction means (15).

21. Plant as in any claim from 16 to 20, characterized in that it comprises sensors (S) disposed downstream of each of the two or more rolling lines (102), suitable to detect and communicate to the control and management unit (21) the contents of alloy elements of the respective finished metal products, and in that a control and management unit (21), on the basis of said contents of alloy elements detected, regulates, in an independent and autonomous manner between one rolling line (102) and the other, the work parameters of said introduction means (15).

22. Plant as in any claim from 16 to 21, characterized in that said sensors (S) are based on LIBS (Laser Induced Breakdown Spectroscopy).

23. Multiple casting method, which provides to:

- feed molten metal material, low in alloy elements, from a feed receptacle (12) to an intermediate container (14);

- divide said molten metal material in said intermediate container (14) into at least two distinct portions;

- introduce alloy elements into at least one portion of said bath of molten metal material in order to enrich said metal material low in alloy elements, in an autonomous and independent manner between one portion and the other, obtaining enriched metal materials, chemically differentiated from each other;

- cast along respective casting lines (11) said portions of enriched metal materials, in an independent and autonomous manner between one portion and the other.

24. Method for multi-line co-rolling of two or more finished metal products, chemically differentiated from each other, which provides:

- multiple casting as in claim 23;

- multi-line rolling, wherein each of said enriched metal materials, chemically differentiated from each other, is rolled by means of a respective rolling line (102), associated with a respective casting line (11), in order to obtain said finished metal products.