Furnace systems and methods for stirring a metal material

Abstract

The disclosure describes a furnace system and a method for electromagnetic stirring of a metal melt. The furnace system includes a furnace for melting a metal material and a stirring system. The stirring system consists of at least two electromagnetic stirring units. The electromagnetic stirring units are located beneath the furnace on the vertices of an N-polygon. N is the number of electromagnetic stirring units. Each electromagnetic stirring unit is configured to induce a force on the metal material along a main direction of each electromagnetic stirring unit. The projection of the main direction of each electromagnetic stirring unit into a horizontal plane defines a main axis of each electromagnetic stirring unit. Each main axis of each electromagnetic stirring unit essentially passes through the center of the N-polygon.

Description

[0001] Furnace systems and methods for stirring a metal material

[0002] Technical field

[0003] The present disclosure relates to a furnace system including a furnace and a stirring system. Further, the disclosure relates to a method for electromagnetic stirring of a metal melt.

[0004] Technical Background

[0005] Traditionally, a metal material is melted inside a furnace. The metal material inside the furnace is stirred to mix the metal material and to achieve a uniform heat distribution inside the metal material. Electromagnetic stirring units are used for stirring the metal material without direct contact between the stirring system and the metal material. Such stirring systems may consist of one or multiple electromagnetic stirring units. Usually, in case of multiple stirring units, the electromagnetic stirring units are arranged such that the forces induced by all electromagnetic stirring units are directed parallel to a common axis.

[0006] Stirring systems, according to the state of the art, have a couple of disadvantages. For example, the mixing strength of the metal material may be insufficient; the melting rate of unmolten metal material may be insufficient; and / or unmolten metal material may be directed to the side wall of the furnace. In example, if direct reduced iron is received by the furnace, the melting rate might be insufficient to properly melt all the received material. The not properly molten material may form ferrobergs and may move to the side wall of the furnace. The ferrobergs on the side wall of the furnace may create operational problems.

[0007] Description of disclosure

[0008] According to an aspect of the disclosure, a furnace system is described. The furnace system includes a furnace for melting a metal material and a stirring system consisting of at least two electromagnetic stirring units. The electromagnetic stirring units are located beneath the furnace on the vertices of an N-polygon. N corresponding to the number of electromagnetic stirring units. Each electromagnetic stirring unit is configured to induce a force on the metalmaterial along a main direction of each electromagnetic stirring unit. The projection of the main direction of each electromagnetic stirring unit into a horizontal plane defines a main axis of each electromagnetic stirring unit. Each main axis of each electromagnetic stirring unit essentially passes through the center of the N-polygon.

[0009] According to an aspect of the disclosure, an electric arc furnace system is described. The electric arc furnace system includes an electric arc furnace for melting a metal material, a plurality of electrodes and a stirring system consisting of at least two electromagnetic stirring units. The electromagnetic stirring units are located beneath the furnace on the vertices of an N-polygon. N corresponding to the number of electromagnetic stirring units. Each electromagnetic stirring unit is configured to induce a force on the metal material along a main direction of each electromagnetic stirring unit. The projection of the main direction of each electromagnetic stirring unit into a horizontal plane defines a main axis of each electromagnetic stirring unit. A projection of each electrode of the plurality of electrodes in the horizontal plane defines a projected circumference of each electrode. A scaled circumference of each electrode corresponds to the projected circumference scaled by a factor of three or lower, such as two, 1.5 or even 1 (i.e., no scaling). A heating area encloses the scaled circumferences of all electrodes. A heating area periphery encompasses the heating area. The heating area periphery is defined as the shortest possible closed line enclosing the scaled circumferences of all electrodes. Particularly, the periphery of the heating area is minimized, that is, the shortest possible closed line (i.e., a closed line has no end points) that encloses the scaled circumferences of all electrodes is the heating area periphery. Each main axis of each electromagnetic stirring unit passes through the heating area.

[0010] According to an aspect of the disclosure, a method for electromagnetic stirring of a metal material is described. The method includes generating a magnetic field inside a furnace. The furnace is configured for melting a metal material. The magnetic field consists of at least two linear traveling magnetic fields. The linear traveling magnetic fields are generated at the vertices of an N-polygon. N is the number of linear traveling magnetic fields. Each linear traveling magnetic field induces a force on the metal material along a main direction of each linear traveling magnetic field. The projection of the main direction of each linear traveling magnetic field into a horizontal plane defines a main axis of each linear traveling magnetic field. Each main axis of each linear traveling magnetic field essentially passes through the center of the N-polygon.According to an aspect of the disclosure, a method for electromagnetic stirring of a metal material is described. The method includes generating a magnetic field inside an electric arc furnace. The electric arc furnace comprising a plurality of electrodes and being configured for melting a metal material. The magnetic field consists of at least two linear traveling magnetic fields. The linear traveling magnetic fields are generated at the vertices of an N-polygon. N is the number of linear traveling magnetic fields. Each linear traveling magnetic field induces a force on the metal material along a main direction of each linear traveling magnetic field. The projection of the main direction of each linear traveling magnetic field into a horizontal plane defines a main axis of each linear traveling magnetic field. A projection of each electrode of the plurality of electrodes in the horizontal plane defines a projected circumference of each electrode. A scaled circumference of each electrode corresponds to the projected circumference scaled by a factor of three or lower, such as two, 1.5 or even 1 (i.e., no scaling). A heating area encloses the scaled circumferences of all electrodes. A heating area periphery encompasses the heating area. The heating area periphery is defined as the shortest possible closed line enclosing the scaled circumferences of all electrodes. Particularly, the periphery of the heating area is minimized, that is, the shortest possible closed line (i.e., a closed line has no end points) that encloses the scaled circumferences of all electrodes is the heating area periphery. Each main axis of each linear traveling magnetic field essentially passes through the heating area.

[0011] In view of the above, embodiments of the present disclosure aim to provide furnace systems including a furnace and a stirring system consisting of at least two electromagnetic stirring units. The electromagnetic stirring units of the stirring system may be configured to induce a flux in the metal material which, in a top view, has mainly a radial component. The radial component may be either pointing from the side wall of the furnace to the center of the furnace or from the center of the furnace to the side wall of the furnace.

[0012] According to an aspect of the disclosure, it may be advantageous if the main axes of all electromagnetic stirring units are passing essentially through a common point or area. This may create a flux of the metal material essentially in the direction of the common point or area. This may guide unmolten floating material in the direction of the common point or area.

[0013] At least some disadvantages of the state of the art are overcome. In particular, embodiments of the present disclosure provide at least one or more of the following advantages: (a) increased mass and heat transfer; (b) enhanced chemical composition; (c) enhanced temperature homogenization; (d) speed up of the solid metal material melting and refining process; (e)reduced energy consumption; (f) reduced refractory consumption; and / or (g) increased furnace productivity. Further, a flux of the metal material may be induced guiding floating, unmolten material away from the side wall of the furnace in the direction of the center of the furnace. Hence, so-called ferroberg formation may be reduced. Additionally, ferrobergs may be guided away from the side wall of the furnace, where they would cause operational problems, and ferroberg melting may be increased.

[0014] According to an aspect of the disclosure, the furnace may be at least one of (a) an electric arc furnace; (b) a top charged furnace; (c) a flat bath operation furnace; (d) a ladle furnace; (e) an aluminum melting furnace; (f) an aluminum holding furnace; (g) a copper anode furnace; (h) a lead melting furnace; and / or (i) any other kind of furnace capable of melting a metal. Each electromagnetic stirring unit of the stirring system may be located beneath the furnace. Optionally, at least one electromagnetic stirring unit may be located beneath a non-magnetic portion of the furnace. More optionally, all electromagnetic stirring units may be located beneath a non-magnetic portion of the furnace.

[0015] According to an aspect of the disclosure, the plurality of electrodes of an electric arc furnace may be supplied with AC current.

[0016] According to an aspect of the disclosure, an electromagnetic stirring unit may be configured to create a linear traveling magnetic field. The electromagnetic stirring unit may use at least two induction coils to create the linear traveling electromagnetic field. Optionally, the electromagnetic stirring unit may include a core around which the induction coils are at least partially wound. The electromagnetic stirring unit may be configured to induce a force on a metal material along a main direction. The main direction of an electromagnetic stirring unit mounted to a furnace may have a horizontal component and may have a vertical component. The main axis of the electromagnetic stirring unit may be an infinite, directionless extension of the horizontal component of the main direction.

[0017] According to an aspect of the disclosure, the stirring system may consist of at least two electromagnetic stirring units. Optionally, the stirring system may consist of at least three electromagnetic stirring units. More optionally, the stirring system may consist of at least four electromagnetic stirring units. Even more optionally, the stirring system may consist of exactly two electromagnetic stirring units.According to an aspect of the disclosure, all electromagnetic stirring units located directly beneath a furnace may be part of the stirring system. The furnace system may include no other electromagnetic stirring unit located beneath the furnace. Optionally, the furnace system may include no other electromagnetic stirring unit.

[0018] According to an aspect of the disclosure, the location of an electromagnetic stirring unit in the horizontal plane may be defined as the center of the polygon defined by the projection of the perimeter of the electromagnetic stirring unit in a horizontal plane.

[0019] An N-polygon is well known to the skilled person. Reference is made to the definition of the N-polygon in geometry according to which a polygon is a figure made up of line segments connected to form a closed polygonal chain in the Euclidean space. An N-polygon, or also N-gon, is understood as a polygon with N sides. For instance, a triangle is a 3-polygon or 3-gon. The segments of the closed polygonal chain are called its edges or sides. The points where two edges meet are the polygon's vertices or corners.

[0020] According to an aspect of the disclosure, the center of the N-polygon may be calculated from the location of the vertices of the N-polygon. The location of the center may be the mean of the locations of the vertices. The location of the center of a polygon may be calculated as: xc= —

[0021] where xcis the x-coordinate of the center of the polygon, ycis the

[0022]

[0023] y-coordinate of the center of the polygon, xnare the x-coordinates of the vertices of the polygon, ynare the y-coordinates of the vertices of the polygon, N is the number of vertices of the polygon and n is a natural number with 1 < n < N. For example, a polygon with four vertices located at (1, 0), (0, 1), (-1, 0) and (0, -1) may have its center at ((l+0-l+0) / 4, (0+l+0-l) / 4) = (0,0). The center of an irregular and / or non-symmetric polygon may be calculated in the same way. According to an aspect of the disclosure, the main axis of an electromagnetic stirring unit may essentially pass through the center of the N-polygon if the angle a formed between the main axis of the electromagnetic stirring unit and a line connecting the location of the electromagnetic stirring unit in the horizontal plane and the center of the N-polygon is less than 25°, optionally less than 20°, even more optionally less than 15°, even more optionally less than 10° or even more optionally less than 5°.According to an aspect of the disclosure, the main axis of an electromagnetic stirring unit may essentially pass through the center of the N-polygon if the main axis of the electromagnetic stirring unit passes through the heating area.

[0024] According to an aspect of the disclosure, the heating area may include the center of the N-polygon.

[0025] According to an aspect of the disclosure, a projection of a heating region in the horizontal plane defines a projected circumference of the heating region. The heating region may be the region of heat generation inside the furnace. Optionally, the heating region may be the region of the main heat generation inside the furnace. Alternatively, the projected circumference of a heating region corresponds to a projection of the heat generating device in the horizontal plane. A scaled circumference of each heating region corresponds to the projected circumference of the heating region scaled by a factor of X. For example, X may be 3, 2.5, 2, 1.5, 1 or 0.5. A 1-times scaled circumference of the heating device may correspond to no scaling, which might be understood as the scaled circumference is equal to the projected circumference.

[0026] A scaled circumference of a projected circumference may have the same geometry as the projected circumference. The center of the scaled circumference may be overlapping with the center of the projected circumference. The geometry of the scaled circumference may be larger, equal or smaller compared to the geometry of the projected circumference.

[0027] For example, a three-times scaled circle of a projected circle with a radius of R may be a circle with a radius of 3 times R. For example, a three-times scaled ellipse of a projected ellipse with a semi-major axis of Rmajorand a semi-minor axis of may be an ellipse with a semi-major

[0028]

[0029] axis of 3 times Rmajorand a semi-minor axis of 3 times Rminor. For example, a three-times scaled N-polygon of a projected N-polygon may have N vertices. The center of the scaled N-polygon and the center of the projected N-polygon may be identical. Compared to the projected N-polygon, each vertex of the scaled polygon may have a distance to the center of the N-polygon three times larger than the distance of the corresponding vertex of the projected N-polygon to the center of the N-polygon. Each axis passing through a vertex of the scaled polygon and the center of the N-polygon is identical to the axis passing through the corresponding vertex of the project N-polygon and the center of the N-polygon. For example, a projected circumference may be partially circular, elliptical and / or polygonal. A scaled circumference of such a projected circumference may be derived for the circular, the elliptical and / or the polygonal part of the projected circumference according to the above described examples.According to an aspect of the disclosure, the plurality of electrodes may be arranged in any configuration. For example, the electrodes may be arranged on the vertices of an E-polygon, wherein E is the number of electrodes. For example, the electrodes may be arranged on the vertices of a regular E-polygon, wherein E is the number of electrodes. For example, the electrodes may be arranged in a line. For example, the electrodes may be arranged on the vertices of an irregular E-polygon.

[0030] According to an aspect of the disclosure, the heating area may enclose a X-times scaled circumference of each electrode. For example, X may be 3, 2.5, 2, 1.5 1, or 0.5. A 1-times scaled circumference of the heating device may correspond to no scaling, which might be understood as the scaled circumference is equal to the projected circumference.

[0031] According to an aspect of the disclosure, the heating area may enclose a scaled circumference of an electrode if the area of the scaled circumference of the electrode is fully included in the area of the heating area.

[0032] According to an aspect of the disclosure, the perimeter of the heating area may be minimized. For example, the heating area is defined such that the heating area encloses the scaled circumference of all electrodes while minimizing the perimeter of the heating area.

[0033] According to an aspect of the disclosure, a 2-polygon may be defined by a stirring system consisting of two electromagnetic stirring units. For example, the 2-polygon may have two vertices located at each of the two electromagnetic stirring units. In the context of geometry, the 2-polygon may also be referred to as bigon, digon and / or 2-gon. Optionally, the 2-polygon may be defined as a double covering of a line segment. For example, vertex A might be connected with vertex B by a first straight line and vertex B might be connected with vertex A by a second straight line. The first and second straight line may be fully overlapping. Therefore, in practice, the two vertices of a 2-polygon may be considered to lie on a straight line connecting the two vertices.

[0034] According to an aspect of the disclosure, the stirring unit may consist of at least three electromagnetic stirring units.

[0035] According to an aspect of the disclosure, each electromagnetic stirring unit of the stirring system may individually induce a force on the metal material towards the center of the N-polygon or away from the center of the N-polygon.According to an aspect of the disclosure, each electromagnetic stirring unit of the stirring system may individually induce a force on the metal material towards the heating area or away from the heating area.

[0036] According to an aspect of the disclosure, the furnace system further may include a control unit. The control unit may be configured to individually, operate each electromagnetic stirring unit to adjust the force, applied on a metal material, induced by each electromagnetic stirring unit. For example, the control unit may be configured to at least adjust, for each electromagnetic stirring unit, one of (a) the direction of the force induced on the metal material; (b) the amplitude of the force induced on the metal material; (c) the strength of the electromagnetic field induced on the metal material; and / or (d) the velocity of the traveling linear electromagnetic field. According to an aspect of the disclosure, the electric arc furnace system further may include a control unit. The control unit may be configured to individually, operate each electromagnetic stirring unit to adjust the force, applied on a metal material, induced by each electromagnetic stirring unit. For example, the control unit may be configured to at least adjust, for each electromagnetic stirring unit, one of (a) the direction of the force induced on the metal material; (b) the amplitude of the force induced on the metal material; (c) the strength of the electromagnetic field induced on the metal material; and / or (d) the velocity of the traveling linear electromagnetic field.

[0037] According to an aspect of the disclosure, the N-polygon may be a regular N-polygon. In the context of the disclosure, a regular polygon may satisfy at least one of the following conditions: (a) the polygon is equiangular, that is, all angles are equal; (b) the polygon is equilateral, that is, all sides of the polygon have an equal length, (c) the polygon is equidistant, that is, all vertices of the polygon have an equal distance to the center of the polygon. Optionally, a regular polygon may be equiangular and equilateral.

[0038] According to an aspect of the disclosure, in a top view, the center of the N-polygon may overlap with the center of the furnace. For example, in a top view may be interpreted as a projection of the perimeter of the furnace in a horizontal plane of the N-polygon. The perimeter of the furnace may be defined by the portion of the furnace holding the metal material. The location of the center of a polygonal furnace may be calculated as the mean of the location of the vertices of the polygon. The center of a furnace with a predominantly circular shape may be located in the center of the circle. The center of a furnace with a predominantly elliptical shape may be located in the center of the ellipse.According to an aspect of the disclosure, in a top view, the heating area may overlap with the center of the furnace.

[0039] According to an aspect of the disclosure, in a top view, a furnace may have a predominantly circular shape. A furnace may have a predominantly circular shape, if at least 50% of the perimeter of the portion of the furnace holding the metal material follows a circular shape. Optionally, a furnace may have a predominantly circular shape, if at least 75% of the perimeter of the portion of the furnace holding the metal material follows a circular shape. More optionally, a furnace may have a predominantly circular shape, if the whole perimeter of the portion of the furnace holding the metal material follows a circular shape.

[0040] According to an aspect of the disclosure, in a top view, a furnace may have a predominantly elliptical shape. A furnace may have a predominantly elliptical shape, if at least 50% of the perimeter of the portion of the furnace holding the metal material follows an elliptical shape. Optionally, a furnace may have a predominantly elliptical shape, if at least 75% of the perimeter of the portion of the furnace holding the metal material follows an elliptical shape. More optionally, a furnace may have a predominantly elliptical shape, if the whole perimeter of the portion of the furnace holding the metal material follows an elliptical shape.

[0041] According to an aspect of the disclosure, the perimeter of the furnace may be defined by the portion of the furnace holding the metal material. In case of a polygonal perimeter of the furnace, the term radially may particularly be interpreted as pointing to or away from the center of the polygon defined by the perimeter of the furnace.

[0042] According to an aspect of the disclosure, the furnace may be an electric arc furnace. Optionally, in a top view, the arc of the electric arc furnace may be created at the center of the N-polygon. Optionally, the arc of the electric arc furnace may be created at the center of the furnace. According to an aspect of the disclosure, the arc of the electric arc furnace system may be created at the center of the furnace.

[0043] According to an aspect of the disclosure, the electromagnetic stirring units may generate a force on the metal material from the center of the furnace radially outward to the side wall of the furnace. The force may induce a flux of the metal material which is directed from the center of the furnace to the side wall of the furnace in a bottom portion of the metal material; upward on the side wall of the furnace; from the side wall of the furnace to the center of the furnace in thetop portion of the metal material; and downward at the center of the furnace. For example, the flux may cause unmolten, floating material to propagate to the center of the furnace.

[0044] According to an aspect of the disclosure, the electromagnetic stirring units may generate a force on the metal material from the center of the N-polygon radially outward to the side wall of the furnace. The force may induce a flux of the metal material which is directed from the center of the N-polygon to the side wall of the furnace in a bottom portion of the metal material; upward on the side wall of the furnace; from the side wall of the furnace to the center of the N-polygon in the top portion of the metal material; and downward at the center of the N-polygon. For example, the flux may cause unmolten, floating material to propagate to the center of the N-polygon.

[0045] According to an aspect of the disclosure, the electromagnetic stirring units may generate a force on the metal material from the heating area radially outward to the side wall of the furnace. The force may induce a flux of the metal material which is directed from the heating area to the side wall of the furnace in a bottom portion of the metal material; upward on the side wall of the furnace; from the side wall of the furnace to the heating area in the top portion of the metal material; and downward at the heating area. For example, the flux may cause unmolten, floating material to propagate to the heating area.

[0046] According to an aspect of the disclosure, at least one electromagnetic stirring unit may apply a force on the metal material directed from the center of the furnace to the side wall of the furnace and at least one electromagnetic stirring unit may apply a force on the metal material directed from the side wall of the furnace to the center of the furnace.

[0047] According to an aspect of the disclosure, at least one electromagnetic stirring unit may apply a force on the metal material directed from the center of the N-polygon to the side wall of the furnace and at least one electromagnetic stirring unit may apply a force on the metal material directed from the side wall of the furnace to the center of the N-polygon.

[0048] According to an aspect of the disclosure, at least one electromagnetic stirring unit may apply a force on the metal material directed from the heating area to the side wall of the furnace and at least one electromagnetic stirring unit may apply a force on the metal material directed from the side wall of the furnace to the heating area.According to an aspect of the disclosure, all electromagnetic stirring units may be configured to induce a force on the metal material directed from the center of the furnace and / or from the center of the N-polygon and / or from the heating area to the side wall of the furnace.

[0049] According to an aspect of the disclosure, all electromagnetic stirring units may be configured to induce a force on the metal material directed from the side wall of the furnace to the center of the furnace and / or to the center of the N-polygon and / or to the heating area.

[0050] According to an aspect of the disclosure, the furnace system may further include at least one supply area for receiving material. An electromagnetic stirring unit may be located beneath at least one supply area. Optionally, an electromagnetic stirring unit may be located beneath each supply area.

[0051] According to an aspect of the disclosure, the electric arc furnace system may further include at least one supply area for receiving material. An electromagnetic stirring unit may be located beneath at least one supply area. Optionally, an electromagnetic stirring unit may be located beneath each supply area.

[0052] According to an aspect of the disclosure, the furnace system may include at least one supply area for receiving material. The supply area may be, at least partially, outside the heating area. Optionally, the supply area may be, at least partially, inside the heating area.

[0053] According to an aspect of the disclosure, the electric arc furnace system may include at least one supply area for receiving material. The supply area may be, at least partially, outside the heating area. Optionally, the supply area may be, at least partially, inside the heating area. According to an aspect of the disclosure, an electromagnetic stirring unit may be located beneath a supply area if, in a top view, the supply area and the electromagnetic stirring unit overlap at least partially. The supply area may be defined as the area intended to receive material. Optionally, at least 90% of the material intended to be received in a supply area may be received in the supply area. More optionally, all of the material intended to be received in a supply area may be received in the supply area.

[0054] According to an aspect of the disclosure, the material received in a supply area may be at least one of (a) scrap; (b) direct reduced iron; (c) briquetted iron; (d) ferroalloys; (e) pig iron; (f) hot metal; and / or (g) a mixture of metallic materials and oxides.According to an aspect of the disclosure, different materials may be received at different supply areas. The material may be received at the same time and / or at different times. The material may be received at different supply areas according to a work cycle program.

[0055] According to an aspect of the disclosure, different materials may be received at the same supply area. The material may be received at the same time and / or at different times. The material may be received at the same supply area according to a work cycle program.

[0056] According to an aspect of the disclosure, the material received in the supply area may be (a) continuous charging from the side wall of the furnace; (b) continuous charging from the roof of the furnace; (c) bucket charging from the open roof; (d) bucket charging from a shaft installed above the furnace bath; and / or (e) any other method for charging material to be received in a supply area.

[0057] According to an aspect of the disclosure, the furnace system may further include a flux bridge. The flux bridge may guide the magnetic flux from at least one electromagnetic stirring unit to at least one other electromagnetic stirring unit.

[0058] According to an aspect of the disclosure, the electric arc furnace system may further include a flux bridge. The flux bridge may guide the magnetic flux from at least one electromagnetic stirring unit to at least one other electromagnetic stirring unit.

[0059] According to an aspect of the disclosure, at least one electromagnetic stirring unit may create a magnetic flux predominantly leaving the electromagnetic stirring unit in the direction of the center of the N-polygon. A majority of the flux predominantly leaving the electromagnetic stirring unit in the direction of the center of the N-polygon may pass through the flux bridge and may enter a different electromagnetic stirring unit. The flux entering the different electromagnetic stirring unit may enter the different electromagnetic stirring unit on a side facing the center of the N-polygon.

[0060] According to an aspect of the disclosure, at least one electromagnetic stirring unit may create a magnetic flux predominantly leaving the electromagnetic stirring unit in the direction of the heating area. A majority of the flux predominantly leaving the electromagnetic stirring unit in the direction of the heating area may pass through the flux bridge and may enter a different electromagnetic stirring unit. The flux entering the different electromagnetic stirring unit may enter the different electromagnetic stirring unit on a side facing the heating area.According to an aspect of the disclosure, the majority of magnetic flux leaving and / or entering each electromagnetic stirring unit on the side of the electromagnetic stirring unit facing the center of the N-polygon and / or the heating area may enter and / or leave the flux bridge.

[0061] According to an aspect of the disclosure, the flux bridge may facilitate the mounting of the stirring system to a location beneath the furnace and / or the mounting of the stirring system to the furnace.

[0062] According to an aspect of the disclosure, the flux bridge may satisfy at least one of the following properties: (a) in a top view, the flux bridge overlaps with the center of the N-polygon defined by the stirring system; (b) in a top view, the flux bridge overlaps with the center of the furnace; (c) the material of the flux bridge is the same material as the material of the core of at least one of the electromagnetic stirring units of the stirring system; (d) the flux bridge has the same cross-section as at least one of the electromagnetic stirring units of the stirring system, optionally, the flux bridge has the same cross-section as the core of at least one of the electromagnetic stirring units of the stirring system; (e) the flux bridge is in physical contact with at least two electromagnetic stirring units of the stirring system; (f) in a top view, the flux bridge overlaps with the heating area; and / or (g) the flux bridge is separated from at least one of the electromagnetic stirring units by a small gap, optionally the gap is smaller than 10cm, more optionally the gap is smaller than 5cm or even more optionally the gap is smaller than 1cm.

[0063] According to an aspect of the disclosure, the stirring system may consist of a maximum of six electromagnetic stirring units. Hence, 2 < N < 6. And N is the number of electromagnetic stirring units included in the stirring system.

[0064] According to an aspect of the disclosure, the stirring system may be mounted to the furnace. The stirring system may follow the movement of the furnace. The movement of the furnace may include translations and / or rotations.

[0065] According to an aspect of the disclosure, the stirring system may not be mounted to the furnace. The furnace may be moved without the stirring system. The movement of the furnace may include translations and / or rotations.

[0066] According to an aspect of the disclosure, the method may further include adjusting a parameter of at least one linear traveling magnetic field. Each linear traveling magnetic field may includeat least one or more of the following parameters: (a) traveling direction; (b) maximum intensity; and / or (c) traveling speed.

[0067] According to an aspect of the disclosure, the method may further include receiving material in at least one supply area. The force induced on the metal material may create a flux of the metal material. The flux of the metal material may guide the received material in the direction of the center of the N-polygon and / or in the direction of the center of the furnace and / or in the direction of the heating area.

[0068] According to an aspect of the disclosure, the method may further include controlling the flux of the metal material according to a work cycle program by adjusting at least one parameter. The work cycle program may include at least one of the following steps: (a) melting of the received material; and / or (b) mixing of the metal material.

[0069] According to an aspect of the disclosure, the work cycle program may include further steps. For example, the work cycle program may include a step for removing, at least partially, the metal material from the furnace.

[0070] According to an aspect of the disclosure, the work cycle program may include charging of material to be received in a supply area.

[0071] According to an aspect of the disclosure, the work cycle program may repeat at least twice the steps of melting received material and mixing the metal material.

[0072] According to an aspect of the disclosure, a metal material may be understood as a material including at least some metal. The metal material may already be partially molten. Optionally, the material may already be molten completely. Alternatively, the metal material may not be molten.

[0073] According to an aspect of the disclosure, any feature described herein referring to the furnace system and / or to the electric arc furnace system may be included in the furnace system and / or in the electric arc furnace system.

[0074] According to an aspect of the disclosure, any feature described herein for the furnace system and / or the electric arc furnace system may be included in the method for stirring of a metal material. Any step implied by features of the furnace system and / or electric arc furnace system may be included in the method for stirring of a metal material.

[0075] Brief description of the figuresIn the following, examples for the disclosure are described in more detail with reference to the drawings. Therein:

[0076] Figure la-f show schematic drawings of a top view of six different embodiments of the stirring system according to the present disclosure,

[0077] Figure 2a, b show schematic drawings of a top view of two different embodiments of the stirring system according to the present disclosure,

[0078] Figure 3a-c show schematic drawings of the flux of the metal material for a certain stirring program according to the present disclosure,

[0079] Figure 4a, b show schematic drawings of the flux of the metal material for certain stirring programs according to the present disclosure,

[0080] Figure 5 shows a schematic drawing of a top view of an electric arc furnace system including supply areas according to the present disclosure,

[0081] Figure 6a, b show schematic drawings of a top view of two furnace systems including a flux bridge according to the present disclosure,

[0082] Figure 7 shows a schematic drawing of a top view of an embodiment of the stirring system according to the present disclosure,

[0083] Figure 8a-c show schematic drawings of a top view of three different embodiments of the furnace system according to the present disclosure,

[0084] Figure 9 shows a schematic drawing of a cross-section of a furnace system according to the present disclosure,

[0085] Figure 10a, b show schematic drawings of electrodes and the heating area according to the present disclosure,

[0086] Figure 10c shows a schematic drawing of a top view of an electric arc furnace system according to the present disclosure,

[0087] Figure 11 shows a schematic drawing of a top view of an electric arc furnace system according to the present disclosure.

[0088] Detailed description of the figures

[0089] In the following possible embodiments of the disclosure are described with reference to the figures. The embodiments are only examples of the disclosure and do not limit the disclosure to the features shown in the figures.Figure la-f show different embodiments of a stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. The embodiments of the figures might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0090] Figure la and lb illustrate a stirring system consisting of two electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28 defined by the electromagnetic stirring units 20. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0091] Figure 1c illustrates a stirring system consisting of three electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0092] Figure Id illustrates a stirring system consisting of four electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit (20) has a main axis (22) passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0093] Figure le illustrates a stirring system consisting of five electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0094] Figure If illustrates a stirring system consisting of six electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0095] Figure 2a and 2b show different embodiments of a stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. Theembodiments of the figures might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0096] Figure 2a illustrates a stirring system consisting of three electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of an irregular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0097] Figure 2b illustrates a stirring system consisting of five electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of an irregular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0098] Figure 3a and 3b show an embodiment of a stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. Figure 3c shows a cross-section of the furnace system. The embodiments of the figures might also include a heating are (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0099] Figure 3a-c illustrate a stirring system consisting of four electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0100] Each electromagnetic stirring unit 20 induces a force on the metal material 18 along the main axis 22 of the electromagnetic stirring unit 20 radially outward. Figure 3a illustrates the flux of the metal material 18 in the bottom portion of the metal material 18. In the bottom portion of the metal material 18 the flux of the metal material 18 is directed radially outward from the center of the furnace 12 to the side wall of the furnace 10. Figure 3b illustrates the flux of the metal material 18 in the top portion of the metal material 18. In the top portion of the metal material 18 the flux of the metal material 18 is directed radially inward from the side wall of the furnace 10 to the center of the furnace 12. Figure 3c illustrates a cross-section view of the furnace system. The stirring system induces a force on the metal material 18. The force inducesa flux of the metal material 18 which is directed from the center of the furnace 12 to the side wall of the furnace 10 in the bottom portion of the metal material 18; upward on the side wall of the furnace 10, from the side wall of the furnace 10 to the center of the furnace 12; and downward at the center of the furnace 12.

[0101] In an embodiment of the disclosure, the above-described flux may be induced by a stirring system including at least two electromagnetic stirring units. Optionally, the above-described flux may be induced by a stirring system consisting of two, three, four, five or six electromagnetic stirring units.

[0102] In an embodiment of the disclosure, the force induced by the electromagnetic stirring units 20 may be reversed. The force induces a flux of the metal material 18 which may be reversed in comparison to the flux illustrated in figure 3a-c.

[0103] Figure 4a and 4b show different embodiments of a stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. The embodiments of the figures might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0104] Figure 4a and 4b illustrate a stirring system consisting of four electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28.

[0105] Two of the electromagnetic stirring units 20 induce a force on the metal material 18 directed from the side wall of the furnace 10 to the center of the furnace 12. The other two electromagnetic stirring units 20 induce a force on the metal material 18 directed from the center of the furnace 12 to the side wall of the furnace 10. The force induced by the stirring system induces a turbulent flux in the metal material 18. The turbulent flux of the metal material 18 causes the metal material 18 to properly mix.

[0106] Figure 5 shows an embodiment of a stirring system beneath a furnace 10. The image shows the furnace system in a top view, hence as projection in a horizontal plane. The embodiment of the figure might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.Figure 5 illustrates a stirring system consisting of four electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28. The furnace 10 is an electric arc furnace. The electrodes 14, creating the electric arc, are in the center of the furnace 12. Supply areas 16, for receiving material, are located above two of the four electromagnetic stirring units. One of the supply areas 16 is not located above an electromagnetic stirring unit. The through each projection of each supply area in the horizontal plane passes a main axis of an electromagnetic stirring unit. Two of the supply areas 16 are located at the center of an electromagnetic stirring unit, respectively.

[0107] Figure 6a and 6b show different embodiments of a stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. The embodiments of the figures might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0108] Figure 6a illustrates a stirring system consisting of five electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28. A flux bridge 26 connects the five electromagnetic stirring units 20 of the stirring system. A majority of the flux of each electromagnetic stirring unit 20 leaving or entering the electromagnetic stirring unit 20 on the side facing the center of the N-polygon 28 is guided by the flux bridge 26. The flux bridge 26 effectively connects the electromagnetic stirring units 20 to a joint electromagnet. The magnetic field created by the joined electromagnet can be adjusted by individually adjusting parameters of each electromagnetic stirring unit.

[0109] Figure 6b illustrates a stirring system consisting of six electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 being located on a vertex of a regular N-polygon 24. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28. A flux bridge 26 connects two of the electromagnetic stirring units 20 of the stirring system. A majority of the flux of the twoelectromagnetic stirring units 20 leaving or entering each of the two electromagnetic stirring units 20 on the side facing the center of the N-polygon 28 is guided by the flux bridge 26. The flux bridge 26 effectively connects the two electromagnetic stirring units 20 to a joint electromagnet. The magnetic field created by the joined electromagnet can be adjusted by individually adjusting parameters of the two electromagnetic stirring units.

[0110] According to an embodiment of the disclosure, the flux bridge 26 may be movable and / or rotatable to connect a different set of electromagnetic stirring units.

[0111] Figure 7 shows an embodiment of the stirring system beneath a furnace 10. The image shows the furnace system in a top view, hence as projection in a horizontal plane. The embodiment of the figure might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0112] Figure 7 illustrates a stirring system consisting of two electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28 defined by the electromagnetic stirring units 20. The furnace 10 is predominantly circular with the center of the furnace 12 overlapping with the center of the N-polygon 28. As understood herein in all embodiments, a main axis 22 of an electromagnetic stirring unit 20 can be understood to pass essentially through the center of the N-polygon 28 if the angle a is less than 25°, optionally less than 20°, even more optionally less than 15°, even more optionally less than 10° or even more optionally less than 5°. The angle a is defined by the main axis 22 of the electromagnetic stirring unit 20 and a line connecting the electromagnetic stirring unit 20 with the center of the N-polygon 28.

[0113] Figure 8a-c show different embodiments of the stirring system beneath a furnace 10. The images show the furnace system in a top view, hence as projection in a horizontal plane. The embodiments of the figures might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0114] Figure 8a and 8b illustrate a stirring system consisting of two electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28 defined by the electromagnetic stirring units 20. The furnace 10 is predominantly circular with the center of the furnace 12 not overlapping with the center of the N-polygon 28.Figure 8c illustrates a stirring system consisting of two electromagnetic stirring units 20 and a furnace 10. Each electromagnetic stirring unit 20 has a main axis 22 passing essentially through the center of the N-polygon 28 defined by the electromagnetic stirring units 20. The furnace 10 has a perimeter with a polygonal shape with the center 12 of the polygon defined by the perimeter of the furnace 10 not overlapping with the center of the N-polygon 28 defined by the stirring system.

[0115] Figure 9 illustrates a furnace system in a cross-section view. The image shows a furnace 10 with a metal material 18 and electromagnetic stirring units 20 controlled by a control unit 30. The control unit 30 may be connected with the electromagnetic stirring units 20 via a physical connection or via a wireless connection. The control unit 30 may be connected individually with each electromagnetic stirring unit 20 of the stirring system or via a distribution box. The embodiment of the figure might also include a heating area (not shown). Exemplary configurations of a heating area are illustrated in figures 10a and 10b.

[0116] Although not shown in the figures 1 through 9, the illustrated furnace systems may have a heating area. The heating area may include the center of the N-polygon 28. Optionally, the heating area may be the projection of a heating region in the horizontal plane. The heating region may be the region of heat generation inside the furnace 10. Optionally, the heating region may be the region of the main heat generation inside the furnace 10. The heating region may include a projected circumference of the heating device (not shown) and an X-times scaled circumference of the heating device. For example, X may be 3, 2.5, 2, 1.5, 1 or 0.5. A 1-times scaled circumference of the heating device may correspond to no scaling, which might be understood as the scaled circumference is equal to the projected circumference.

[0117] Figure 10a and 10b show embodiments of an electric arc furnace system in a top view, hence as a projection in a horizontal plane, according to the present disclosure. The electrodes 14 and their projected circumference is illustrated showing different configurations of the electrodes 14. The electrodes 14 may be arranged in any configuration such as on the corners of a triangle or in a line. The number of electrodes 14 is not limited to three. For example, the number of electrodes might be two, four, five or six. The electric arc furnace may comprise any number of electrodes 14. The projection in a horizontal plane of an electrode 14 is not limited to be circular but may be elliptical, polygonal and / or a combination thereof.

[0118] Around the projected circumference of each electrode 14 a X-times scaled circumference 15 is shown. For example, X equals three. The heating area 19 encloses the scaled circumference ofall electrodes 15. As shown, the periphery of the heating area 19 is minimal while still enclosing the scaled circumference 15 of all electrodes.

[0119] Figure 10c shows an embodiment of a stirring system beneath an electric arc furnace 10. The image shows the electric arc furnace system in a top view, hence as projection in a horizontal plane.

[0120] Figure 10c illustrates a stirring system consisting of four electromagnetic stirring units 20 and an electric arc furnace 10 according to the present disclosure. Each electromagnetic stirring unit 20 is located on a vertex of a regular N-polygon 24. The electrodes 14, creating the electric arc, are in the center of the furnace 12. For each electrode 14 a scaled circumference 15 of the projected circumference of the electrode 14 is indicated. A heating area 19 encloses the three-times scaled circumference 15 of all electrodes 14, wherein the periphery of the heating area is the shortest possible closed line still enclosing the three-times scaled circumference.

[0121] Each electromagnetic stirring unit 20 has a main axis 22 passing through the heating area 19. The heating area 19 includes the center of the N-polygon 28. Each main axis 22 passes through the heating area 19. Supply areas 16, for receiving material, are located above two of the four electromagnetic stirring units. One supply area 16 is not located above an electromagnetic stirring unit. Through each projection of each supply area in the horizontal plane passes a main axis of an electromagnetic stirring unit.

[0122] Figure 11 shows an embodiment of a stirring system beneath an electric arc furnace 10. The image shows the electric arc furnace system in a top view, hence as projection in a horizontal plane.

[0123] There are shown two electromagnetic stirring units 20 located on the vertices of a 2-polygon 24. The center of the 2-polygon 28 is separated from the center of the furnace 12. Further, three electrodes 14 and their projected circumference are depicted. A three-times scaled circumference 15 for each electrode 14 is indicated. A heating area 19 encloses the scaled circumference 15 of all electrodes 14 with the periphery of the heating area 19 being the shortest possible closed line as explained. Each electromagnetic stirring unit 20 has a main axis 22 passing through the heating area 19.

[0124] Individual parts of an embodiment illustrated in the figures are not limited by other parts of the embodiment illustrated in the same figure. For example, the number of electromagnetic stirring units on each figure is only exemplary and might vary.List of reference signs

[0125] 10 furnace

[0126] 12 center of the furnace

[0127] 14 electrode

[0128] 15 scaled circumference

[0129] 16 supply area

[0130] 18 metal material

[0131] 19 heating area

[0132] 20 electromagnetic stirring unit 22 main axis

[0133] 24 N-polygon

[0134] 26 flux bridge

[0135] 28 center of the N-polygon 30 control unit

Claims

Claims1. A furnace system, the furnace system comprising:a furnace (10) for melting a metal material (18) and a stirring system, the stirring system consisting of at least two electromagnetic stirring units (20),wherein the electromagnetic stirring units (20) are located beneath the furnace (10) on the vertices of an N-polygon (24) where N is the number of electromagnetic stirring units (20); wherein each electromagnetic stirring unit (20) is configured to induce a force on the metal material (18) along a main direction of each electromagnetic stirring unit (20);wherein the projection of the main direction of each electromagnetic stirring unit (20) into a horizontal plane defines a main axis (22) of each electromagnetic stirring unit (20); and wherein each main axis (22) of each electromagnetic stirring unit (20) essentially passes through the center of the N-polygon (28).

2. A furnace system according to claim 1,wherein each electromagnetic stirring unit (20) is configured to individually induce a force on the metal material (18) towards the center of the N-polygon (28) and / or away from the center of the N-polygon (28).

3. A furnace system according to any previous claim, further comprising:a control unit (30);wherein the control unit (30) is configured to individually operate each electromagnetic stirring unit (20) toadjust the force, applied on the metal material (18), induced by each electromagnetic stirring unit (20).

4. A furnace system according to any previous claim,wherein the N-polygon (24) is a regular N-polygon (24).

5. A furnace system according to any previous claim,wherein, from a top view, the center of the N-polygon (28) overlaps with the center of the furnace (12).

6. A furnace system according to any previous claim, further comprisinga flux bridge (26);wherein the flux bridge (26) guides the magnetic flux from at least one electromagnetic stirring unit (20) to at least one other electromagnetic stirring unit (20).

7. A furnace system according to any previous claim,wherein the electromagnetic stirring units (20) generate a force on the metal melt (18) from the center of the furnace (12) radially outward to the side wall of the furnace (10); wherein the force induces a flux of the metal material (18), which is directed from the center of the furnace (12) to the side wall in the bottom portion of the metal material (18), upward on the side wall of the furnace (10), from the side wall to the center of the furnace (12) in the top portion of the metal material (18), and downward at the center of the furnace (12).

8. A furnace system according to any previous claim,wherein, during operation, at least one electromagnetic stirring unit (20) induces a force on the metal material (18) directed from the center of the furnace (12) to the side wall of the furnace (10); andwherein, during operation, at least one electromagnetic stirring unit (20) induces a force on the metal material (18) directed from the side wall of the furnace (10) to the center of the furnace (12).

9. A furnace system according to any previous claim,wherein, during operation, all electromagnetic stirring units (20) induce a force on the metal material (18) directed from the center of the furnace (12) to the side wall of the furnace (10); orwherein, during operation, all electromagnetic stirring units (20) induce a force on the metal material (18) directed from the side wall of the furnace (10) to the center of the furnace (12).

10. A furnace system according to any previous claim, further comprising:at least one supply area (16) for receiving material;wherein the main axis of at least one electromagnetic stirring unit (20) passes through the projection of the supply area in the horizontal plane (16).

11. An electric arc furnace system, the electric arc furnace system comprising:a furnace (10) for melting a metal material (18), a plurality of electrodes (14) and a stirring system, the stirring system consisting of at least two electromagnetic stirring units (20), wherein the electromagnetic stirring units (20) are located beneath the furnace (10) on the vertices of an N-polygon (24) where N is the number of electromagnetic stirring units (20); wherein each electromagnetic stirring unit (20) is configured to induce a force on the metal material (18) along a main direction of each electromagnetic stirring unit (20);wherein the projection of the main direction of each electromagnetic stirring unit (20) into a horizontal plane defines a main axis (22) of each electromagnetic stirring unit (20); wherein a projection of each electrode (14) of the plurality of electrodes (14) in the horizontal plane defines a projected circumference of each electrode (14);wherein a scaled circumference (15) of each electrode (14) corresponds to the projected circumference scaled by a factor of three;wherein a heating area (19) is encompassed by a heating area periphery, the heating area periphery being defined as the shortest possible closed line enclosing the scaled circumferences (15) of all electrodes (14); andwherein each main axis (22) passes through the heating area (19).

12. An electric arc furnace system according to claim 11,wherein each electromagnetic stirring unit (20) is configured to individually induce a force on the metal material (18) towards the heating area (19) and / or away from the heating area (19).

13. An electric arc furnace system according to any of claims 11 or 12, further comprising: a control unit (30);wherein the control unit (30) is configured to individually operate each electromagnetic stirring unit (20) to adjust the force, applied on the metal material (18), induced by each electromagnetic stirring unit (20).

14. An electric arc furnace system according to any of claims 11 to 13,wherein, from a top view, the heating area (19) overlaps with the center of the furnace (12).

15. An electric arc furnace system according to any of claims 11 to 14, further comprising a flux bridge (26);wherein the flux bridge (26) guides the magnetic flux from at least one electromagnetic stirring unit (20) to at least one other electromagnetic stirring unit (20).

16. An electric arc furnace system according to any of claims 11 to 15,wherein the electromagnetic stirring units (20) generate a force on the metal melt (18) from the heating area (19) radially outward to the side wall of the furnace (10);wherein the force induces a flux of the metal material (18), which is directed from the heating area (19) to the side wall in the bottom portion of the metal material (18), upward on the side wall of the furnace (10), from the side wall to the heating area (19) in the top portion of the metal material (18), and downward at the heating area (19).

17. An electric arc furnace system according to any of claims 11 to 16,wherein, during operation, at least one electromagnetic stirring unit (20) induces a force on the metal material (18) directed from the heating area (19) to the side wall of the furnace (10); andwherein, during operation, at least one electromagnetic stirring unit (20) induces a force on the metal material (18) directed from the side wall of the furnace (10) to the heating area (19).

18. An electric arc furnace system according to any of claims 11 to 17,wherein, during operation, all electromagnetic stirring units (20) induce a force on the metal material (18) directed from the heating area (19) to the side wall of the furnace (10); or wherein, during operation, all electromagnetic stirring units (20) induce a force on the metal material (18) directed from the side wall of the furnace (10) to the heating area (19).

19. An electric arc furnace system according to any of claims 11 to 18, further comprising: at least one supply area (16) for receiving material;wherein the main axis of at least one electromagnetic stirring unit (20) passes through the projection of the supply area in the horizontal plane (16).

20. A method for electromagnetic stirring of a metal material (18), the method comprising: generating a magnetic field inside a furnace (10), the furnace (10) being configured for melting the metal material (18);wherein the magnetic field consists of at least two linear traveling magnetic fields, wherein the linear traveling magnetic fields are generated on the vertices of an N-polygon (24),wherein N is the number of linear traveling magnetic fields,wherein each linear traveling magnetic field induces a force on the metal material (18) along a main direction of each linear traveling magnetic field,wherein the projection of the main direction of each linear traveling magnetic field into a horizontal plane defines a main axis (22) of each linear traveling magnetic field, wherein each main axis (22) of each linear traveling magnetic field essentially passes through the center of the N-polygon (28).

21. A method according to claim 20, the method further comprising:adjusting a parameter of at least one linear traveling magnetic field,wherein the parameter comprises one or more of the following: traveling direction, maximum intensity and traveling speed.

22. A method according to claim 20 or 21, the method further comprising:receiving material in at least one supply area (16);wherein the force induced on the metal material (18) creates a flux of the metal material (18), wherein the flux of the metal material (18) guides the received material in the direction of the center of the N-polygon (28).

23. A method for electromagnetic stirring of a metal material (18), the method comprising: generating a magnetic field inside an electric arc furnace (10), the electric arc furnace (10) comprising a plurality of electrodes and being configured for melting the metal material (18); wherein the magnetic field consists of at least two linear traveling magnetic fields, wherein the linear traveling magnetic fields are generated on the vertices of an N-polygon (24),wherein N is the number of linear traveling magnetic fields,wherein each linear traveling magnetic field induces a force on the metal material (18) along a main direction of each linear traveling magnetic field,wherein the projection of the main direction of each linear traveling magnetic field into a horizontal plane defines a main axis (22) of each linear traveling magnetic field, wherein a projection of each electrode (14) of the plurality of electrodes (14) in the horizontal plane defines a projected circumference of each electrode (14);wherein a scaled circumference (15) of each electrode (14) corresponds to the projected circumference scaled by a factor of three;wherein a heating area (19) is encompassed by a heating area periphery, the heating area periphery being defined as the shortest possible closed line enclosing the scaled circumferences (15) of all electrodes (14); andwherein each main axis (22) of each linear traveling magnetic field passes through the heating area (19).

24. A method according to claim 23, the method further comprising:adjusting a parameter of at least one linear traveling magnetic field,wherein the parameter comprises one or more of the following: traveling direction, maximum intensity and traveling speed.

25. A method according to claim 23 or 24, the method further comprising:receiving material in at least one supply area (16);wherein the force induced on the metal material (18) creates a flux of the metal material (18), wherein the flux of the metal material (18) guides the received material in the direction of the heating area (19).

Images