Melting furnace and method for melting metal by means of an electrically heatable immersion heating element

Abstract

The invention relates to a melting furnace (100) for melting metal, comprising: - a first heating device (130) having at least one electrically heatable immersion heating element (131); and - a circulating arrangement (120) designed to create a flow of molten metal within the melting furnace (100). The invention also relates to a method for melting metal using a melting furnace (100) of this type.

Description

[0001] StrikoWestofen GmbH

[0002] 237PCT 1722

[0003] Melting furnace and method for melting metal with electrically heated immersion heating element

[0004] The invention relates to a melting furnace and a method for melting metal by means of at least one electrically heatable immersion heating element.

[0005] Melting furnaces for producing a molten metal from solid metal material are well-known and widespread. An example can be found in DE 103 25 153 A1. Although these melting furnaces are already widely used, there is potential for improvement in terms of operating costs and the associated economic efficiency of producing molten metals.

[0006] The present application therefore aims to improve the efficiency and, in particular, the economic viability of producing metal melts using melting furnaces.

[0007] This problem is solved by the subject matter of the appended independent patent claims. Advantageous further developments are specified in the dependent claims and in this description.

[0008] Accordingly, a melting furnace for melting metal is disclosed, including:

[0009] - a first heating device with at least one electrically heatable immersion heating element; and

[0010] - a circulation device designed to generate a flow of molten metal within the melting furnace.

[0011] The invention recognizes that the economic viability of existing melting furnaces is particularly influenced by the energy source used and its costs. Gas has previously been used predominantly as the energy source for melting metals. The invention addresses this issue by instead using electrical energy, at least in part. Depending on the source of the electrical energy, potentially lower costs can be achieved than with operation using gas as the energy source.

[0012] The invention further proposes the use of at least one immersion heating element as an electrically operated heating device. It has been recognized that such an immersion heating element enables particularly efficient heat transfer to the metal and thus particularly effective melting of the metal.

[0013] Melting can also be accelerated by using the circulation device. For example, hot melt can flow around the supplied solid metal, which accelerates the melting of the still solid metal. Additionally or alternatively, the at least one immersion heating element can be flowed around, as explained in more detail below. This improves heat transfer from the immersion heating element to or into the molten metal. The first heating device can comprise at least one control device (for example comprising at least one processor and / or at least one memory device) to control the operation of the immersion heating element. The first heating device can comprise at least one power connection and / or at least one connecting line in order to be able to receive electrical energy.The immersion heating element can be configured to convert the electrical energy into thermal energy, for example by dissipating the electrical energy by means of an electrical resistance.

[0014] The immersion heating element may be immersed or capable of being immersed in the molten metal present or to be produced in the melting furnace, for example, along at least half of its length (for example, at a maximum fill level). The immersion heating element may be generally elongated and / or cylindrical and / or rod-shaped.

[0015] The immersion heating element can comprise ceramic components, in particular a ceramic outer shell or a ceramic jacket. This enables effective heat transfer to the surrounding molten metal. The immersion heating element can also be referred to as an immersion heater or can comprise such an immersion heater. The total power of all immersion heating elements in the melting furnace is at least 50 kW; for melting aluminum alloys, the total power is at least 150 kW.

[0016] Where reference is made herein to a molten metal present in the melting furnace, it is understood that a person skilled in the art can typically clearly deduce the position and extent of the molten metal to be received based on the melting furnace. In particular, openings or lines present in the melting furnace for guiding the molten metal and / or for supplying material to be melted can allow conclusions to be drawn about the possible extent of the molten metal.

[0017] A maximum and minimum fill level of the molten metal in the furnace can also be determined accordingly. The minimum fill level is reached, for example, when at least one immersion heating element is immersed in the melt only to a minimum permissible immersion length. For example, the minimum permissible immersion length cannot be more than one-third or more than one-quarter of the theoretically available or, in other words, the maximum possible immersion length.

[0018] A maximum fill level, however, can be determined by areas of the melting furnace that should not come into contact with molten metal. For example, the height of a charging opening through which metal to be melted can be introduced into the melting furnace, but through which no molten metal should flow out of the melting furnace, can determine a maximum possible fill level.

[0019] To achieve the fill level in the melting furnace at which the immersion heating element is immersed in the melt with its minimum permissible immersion length, the melting furnace can be filled with liquid metal from an external furnace or from a transport ladle, or by other means. Such an initial filling of the melting furnace may be necessary before the melt can be heated or the melted material can be melted by means of heat supplied by the immersion heating element. It may also be necessary before the molten metal flow can be generated by means of the circulation device. A lateral furnace pocket can be provided for filling the melting furnace with liquid metal. This furnace pocket is open at the top and is fluidly connected to the melting furnace.

[0020] In order to detect the fill level in the melting furnace at which the immersion heating element is immersed in the melt with its minimum permissible immersion length, the melting furnace can be equipped with one or more level sensors. The terms level and fill level can be understood as synonymous here. A level sensor can detect the minimum permissible level of the melt in the melting furnace and then transmit a preferably binary signal to a control unit of the first heating device. If the minimum permissible level is present, the control unit can issue approval for operation of the immersion heating element. If the level sensor detects that the minimum level for operation of an immersion heating element is not present, for example because metal has been removed from the melting furnace, the approval for operation of this immersion heating element preferably expires.Alternatively, a sensor can measure the melt level in the melting furnace and transmit an analog signal to a control device. Preferably, the control device compares the current level with the minimum permissible level and generates the corresponding signal to enable operation of the immersion heating element.

[0021] If the melting furnace has a second heating device positioned outside the molten metal, the second heating device can be operated even if the first heating device, namely the immersion heating elements, has not received an operating release from a control unit due to the melt level in the furnace.

[0022] In the same way as described above, the maximum fill level of the melting furnace can be detected, and a control unit can control the furnace's operation. For example, at a maximum fill level, the addition of melt material can be prevented by the control unit preventing the opening of each loading door, for example, by denying the drive units for opening the doors from operating.

[0023] According to a preferred embodiment, the immersion heating element can be surrounded by the molten metal flow. In particular, the immersion heating element can be positioned in a region of the melting furnace through which the molten metal flow flows. Additionally or alternatively, it can be immersed in a region of the molten metal in which the molten metal flow is pronounced and, for example, has a certain minimum velocity. For this purpose, the region can be located in a furnace segment with an inlet opening and an outlet opening, with this furnace segment being flowed through in a defined manner. In other words, the immersion heating element cannot be immersed in a region of the molten metal that is quasi-static or does not flow at a minimum velocity.Several immersion heating elements can be arranged offset in the flow direction so that they block the flow cross-section of the molten metal flow by more than 20%, as viewed from the inlet opening of the chamber.

[0024] In particular, a flow around the immersion heating element can be understood to mean that the convective heat transfer from the immersion heating element to the molten metal is higher (in particular at least 20% higher, at least 50% higher or at least 80% higher, e.g. approximately 100% higher or more) than the heat transfer from the immersion heating element to non-flowing metal of the same temperature and composition (and thus in particular also the same thermal conductivity).

[0025] According to the invention, the melting furnace comprises at least one charging opening for supplying metal to be melted. The melting furnace can be at least partially sealed off from the environment (for example, with the exception of optional open channels) and, in particular, be fireproof. For this purpose, it can have a housing and / or wall areas surrounding an interior of the melting furnace in which the molten metal can be accommodated.

[0026] The melting furnace may be at least partially refractory lined. It may consist of open-topped chutes covered with a removable lid, or may include such chutes. It may consist of areas and / or chambers with non-removable lids, or may include such areas and / or chambers.

[0027] The loading opening can be a targeted opening in the housing or wall areas of the melting furnace. It can be adapted to the size of the loading material. The loading opening can have an area of ​​at least 40 cm 2 it can also be 6 m 2 Depending on the size of the charge (also called melting material), it can be closed, e.g., by means of a door or flap. Metal can flow directly into the melt through the charge opening or first into or onto a charge area of ​​the type explained below.

[0028] For example, the charging opening may form a lateral opening in the melting furnace and / or a non-horizontal opening, which facilitates the supply of metal and reduces the risk of molten metal splashing out. For example, the opening cross-section (or a plane in which it extends) may have an inclination of no more than 45° to a vertical spatial plane.

[0029] Alternatively, the charging opening can be formed by an open ceiling area of ​​the melting furnace, and in particular by a furnace chamber (see definition below), so that melting material can be introduced, for example, by opening an upper cover. The charging opening can also be horizontal or nearly horizontal and, for example, have an inclination of no more than 45° to a horizontal spatial plane. Combinations of differently oriented charging openings (e.g., horizontal and vertical) are also possible.

[0030] The melting furnace and in particular a single furnace chamber can have a plurality of charging openings, in particular a large and a small charging opening of the above type. This can in particular be a furnace chamber with the first or the second heating device.

[0031] However, the charging opening does not necessarily have to be located in a furnace chamber, or at least not in a furnace chamber with a first or second heating device. It can also be provided, for example, in a melt channel with a reduced cross-section between two furnace chambers.

[0032] In general, the melting furnace can be designed to melt a feed material in the form of a continuous metal part or piece weighing up to 1200 kg, for which an appropriately dimensioned feed opening must be provided. The melting furnace can also be additionally or alternatively designed to melt a feed material consisting of several metal parts that are added to the melting furnace from a collecting container. Additionally or alternatively, the melting furnace can also be designed to melt lumpy feed material. This can mean parts to be melted that are added individually to the melt in the furnace, for example, in contrast to a collection of several parts that are pushed or thrown into the furnace from a container. Alternatively or additionally, the melting furnace can be designed to melt metal chips.These can also be fed through a comparatively small loading opening and / or as bulk material.

[0033] The molten metal flow can be generated (for example, by appropriate positioning and / or operation of the circulation device) and / or the feed opening can be positioned such that the molten metal flow flows from the immersion heating element toward the feed opening. This has the advantage that solid metal supplied through the feed opening is not moved directly toward the immersion heating element by the molten metal flow, but may be moved away from it. This reduces the risk of collision between the immersion heating element and the solid metal.For example, in this context, a circulating flow path may be provided as follows: from the circulation device toward a feed opening, from there to the immersion heater, and from there back to the circulation device, whereby the length of the flow path from the feed opening to the immersion heaters may be longer than the length of the flow path from the circulation device to the feed opening. The latter may include the immersion heaters not being positioned in the immediate vicinity of the feed opening.

[0034] Alternatively or additionally, the molten metal flow can be generated in such a way that it flows against or around the feed material in the melt. This can be achieved, for example, by appropriate positioning or alignment relative to a feed opening of the type explained herein. The molten metal flow can, for example, flow below a feed opening and / or directly past it, so that metal added through the feed opening enters the molten metal flow. The flow against and, in particular, around the feed material accelerates its melting. In particular, the molten metal flow can flow against at least a portion of the supplied feed material at a flow velocity that corresponds at least to an average flow velocity, in particular at least twice the average flow velocity, of the molten metal flow during its circulation in the melting furnace.For this purpose, for example, a cross-sectional constriction of a particularly annular melt channel can be provided in the region of a charging opening.

[0035] In general, the circulation device is preferably configured to generate the molten metal flow such that it circulates, in particular continuously, between the immersion heating element and the circulation device. The flow velocity can be set constant or variable, for example, depending on the operating state. In particular, in a pure heat-holding operation, in which no still-solid metal is to be melted, a different and in particular a lower flow velocity can be generated than in a melting operation in which added solid metal is to be melted.

[0036] According to a further aspect, the first heating device is positioned in a furnace chamber, and the circulation device is optionally positioned outside this furnace chamber, but is fluidly connected to it. For example, the circulation device can draw molten metal from the furnace chamber via a melt channel or another melt-conducting connection and convey it back into it under pressure (preferably, however, into another part of the furnace chamber, e.g., through an inlet opening). The melt preferably flows toward, and in particular along, a feed opening of the type disclosed herein before returning to the first heating device.

[0037] A furnace chamber can be understood as a region of the furnace through which the molten metal flows, which has an inflow and an outflow area (e.g., in the form of an inflow and an outflow opening) and, compared to these inflow and outflow areas, has a widening of the maximum flow cross-section of at least 20%. Flow cross-sections considered here can refer to flow-through cross-sections defined by the structure, i.e., in other words, to theoretically or structurally possible flow cross-sections. Alternatively, an actual flow cross-section of the molten metal at maximum fill level can be considered.

[0038] Alternatively or in addition to the above widening, the flow-through region can have a volume increase of at least 20% compared to melt channels connected to the inflow and outflow region (and / or chambers or regions immediately adjacent thereto), in particular based on a common unit of quantity (for example volume per meter).

[0039] The furnace chamber can be separated from the remainder of the furnace, and in particular from the remainder of its melt-carrying interior, by at least one wall. The molten metal can flow from one furnace chamber to another through an opening, in particular forming an inflow area and / or a cross-sectional reduction of the flow path relative to the furnace chamber. The flow cross-section of the inflow area may not exceed 80% of the flow cross-section before and / or after the inflow area.

[0040] A portion of the molten metal collected in a furnace chamber can be technically separated from other portions of the molten metal in such a way that a process (e.g., a holding or melting process) in the furnace chamber does not directly influence a process outside of that chamber. For example, heat generation within the furnace chamber cannot also directly affect the outside of the furnace chamber, but can essentially only be transferred from the furnace chamber via the outflowing molten metal.

[0041] In the case of a plurality of furnace chambers, these can be separated from one another by at least one wall region (or, in other words, at least one partition wall). This wall region or partition wall can, for example, form or comprise a particularly vertical and / or upright wall within a furnace housing or furnace volume. The molten metal can flow along this wall on both sides. According to this variant, the furnace chambers can each be at least partially delimited by the common wall region. Any furnace chamber described herein can be at least partially delimited by at least one outer wall of the melting furnace, wherein the outer wall can generally define a boundary from the surroundings of the furnace.

[0042] Alternatively, a furnace chamber may comprise its own (e.g., stand-alone) housing and be connected to at least one other housing of the furnace (e.g., again comprising or forming at least one furnace chamber). For this purpose, the furnace chamber may, for example, be comprised of a single segment or a single module of the type disclosed herein. This connection may comprise or be implemented as a flow channel, an open channel, or a furnace chamber dimensioned as a flow channel.

[0043] Any furnace chamber described herein can be refractorily lined (i.e., refractorily lined) and, for this purpose, enclosed, for example, by a refractory outer wall (or casing wall). This outer wall can, for example, only be penetrated locally by a feed opening, an inlet and outlet opening, or an optional exhaust line.

[0044] The furnace chamber may comprise at least 10% of the total furnace volume, particularly if it is a comparatively small secondary chamber of a plurality of furnace chambers. Alternatively, the furnace chamber may comprise at least 50% or even at least 70% of the total furnace volume, particularly if it is a comparatively large main chamber of a possible plurality of furnace chambers. The exact proportion may depend in particular on the total number of furnace chambers provided (for example, the higher this number, the lower the proportion).

[0045] In contrast to tubular or upwardly open and generally elongated melt channels, the furnace chamber can be designed to receive the molten metal, forming a large-area melt pool. The area of ​​the melt pool in question can be formed by an exposed and, in particular, horizontal surface of the molten metal. The dimensions of this area can be larger than a cross-sectional area of ​​the melt pool containing a vertical spatial axis.

[0046] In general, flow velocities of the molten metal flow within the furnace chamber can be reduced, for example compared to an inflow velocity and / or an outflow velocity.

[0047] Any furnace chamber disclosed herein may optionally be opened. In particular, an upper wall portion or an optional lid of the furnace chamber may be removable.

[0048] Any furnace chamber disclosed herein may also be a heated (for example, by heating the wall area or irradiating the molten metal from vertically above) or unheated trough. This may be the case if the furnace chamber primarily serves to transfer molten metal, rather than to receive the molten metal for heating by any heating device described herein. However, troughs in which melting takes place can also be provided. A trough can generally be characterized in that a flow cross-section of the furnace upstream and downstream of it can be at least 50% higher (for example, over a length of at least half a meter). The trough can be permanently open at the top or can be at least temporarily closed by a liftable cover.

[0049] One embodiment provides that the circulation device is arranged in another (second) furnace chamber and / or is connected via a melt channel to a (first) furnace chamber in which the at least one immersion heating element is located. The first furnace chamber can form a main chamber of the furnace with the largest volume. In particular, the first furnace chamber can also include a charging opening, but optionally not the circulation device furnace chamber. Alternatively, the circulation device and the first heating device can be arranged in a common furnace chamber.

[0050] According to a further development, the melting furnace has an annular channel, which is an annular (metal) melt channel. The heating device and the circulation device are preferably arranged in the annular channel. The annular channel can be accessible and, in particular, feedable through the charging opening. The annular channel can define an annular melt receiving area. The annular shape can be circular, elliptical, or rectangular, preferably with rounded corner areas. However, the annular shape is not limited to one of these variants. The furnace housing of the melting furnace can also be annular; and / or be shaped generally corresponding to the annular channel; and / or surround or receive the annular channel.

[0051] Preferably, the molten metal flow circulates through the annular channel, in particular as an open channel flow.

[0052] The annular channel may comprise any furnace chamber mentioned herein. In other words, any furnace chamber mentioned herein and any other melt-carrying region of the melting furnace may form a segment of the annular channel. Outside the annular channel, there may be no molten metal flow in the melting furnace, in particular no continuous and / or circulating molten metal flow.

[0053] The melting furnace can have an interior area surrounded by the annular channel. In particular, the interior area can be completely enclosed by the annular channel, e.g., viewed along the circumferential direction of the annular channel. Consequently, a furnace housing surrounding the annular channel can also completely and preferably closedly surround the interior area. The interior area can be open at the top and accessible from there (e.g., by means of ladders, stairs, or cranes). The interior area can remain free and / or define a work area, e.g., for maintenance work. In particular, it can be free of other furnace components. For example, only components firmly connected to a furnace housing can protrude into the interior area. The interior area can be sufficiently large to accommodate a person. For example, it can have an area of ​​at least 1 m 2 and preferably at least 2 m 2 include.

[0054] During furnace operation, various operations and actions can be performed from an external area, i.e., from the sides of the furnace housing facing away from the interior of the furnace. Such external actions can include, in particular, charging the furnace and removing molten metal. Additionally or alternatively, these actions can include scraping the melt surface to remove solid impurities, sampling the melt, alloying, or refining.

[0055] For example, lid lifting devices with drives, cable ducts, and / or electrical terminal boxes (in other words: electrical fuse boxes or switch boxes) may be installed indoors. These indoor furnace elements do not interfere with the work carried out from outside. In particular, access to the melt is unobstructed and is not hindered or blocked by indoor furnace elements. Conversely, the indoor furnace elements are not contaminated or damaged by work carried out outside.

[0056] The annular channel can have a plurality of modules, each through which the molten metal flow flows. The modules can be arranged consecutively and / or lined up in a row along a flow direction of the molten metal. The modules can be arranged and connected to one another in such a way that they jointly define the annular channel disclosed here. Optionally, additional modules can also be provided, which, for example, enable melt to be fed into or removed from the annular channel. These modules do not necessarily have to be flowed through by the circulating molten metal flow, in particular not continuously.

[0057] The modules can form independently handleable and / or independently transportable and / or independently manufactured parts of the melting furnace. They can each comprise at least a section of a furnace housing. Each module can be independently supported on a base. When arranged in series, the modules can contact at least one adjacent module and in particular be connected to this, e.g. by a mechanical connection or by welding. The series can take place along a flow direction of the molten metal flow. Each module can comprise and / or completely form a section (in other words: a channel segment) of the annular channel, whereby this section can extend along the flow direction of the molten metal flow. For example, the section along the flow direction can have a length of at least 0.5 m.

[0058] Each module can have at least one inlet opening, preferably exactly one inlet opening, and at least one outlet opening. The at least one inlet opening can be provided for introducing melt from an adjacent module, in particular from an outlet opening thereof, and can preferably be connected to this outlet opening. A further inlet opening can be provided, for example, for supplying liquid metal into the annular channel. This inlet opening can be connected to or comprise a corresponding supply area. In particular, this further inlet opening can be designed as a branch channel or be fluidly connected to such a channel in order to supply molten metal to the melting furnace. The inlet opening and outlet opening can be opposite one another when viewed along the flow direction of the molten metal flow.The molten metal can flow from a preceding module (viewed in the direction of flow) through the inlet opening. The molten metal can flow into a subsequent module (viewed in the direction of flow) through the outlet opening. Consequently, a module can be flowed through from the inlet opening to the at least one outlet opening. An outlet opening can alternatively be designed as a branch channel or be fluidly connected to such a channel in order to drain molten metal from the melting furnace.

[0059] Each module can be connected to at least two other modules in a fluid-tight manner for transferring the molten metal flow between the modules. Each module can be connected, for example, to a first module by means of an inlet opening and to a second module by means of an outlet opening. This can apply in particular to modules that together form an annular channel as disclosed here and / or are arranged in series in the direction of flow. It is not excluded that there are additional modules (e.g. for liquid metal supply or melt removal) that are connected to only one module but do not, for example, themselves form a section of the annular channel.

[0060] To connect the modules, the flanges of the modules can be screwed, welded, or otherwise connected. The connection can be sealed or sealed. Each module can preferably be connected to any other module. Consequently, the modules can have uniform interface areas for connecting to other modules. The interface areas can be characterized, for example, by uniform dimensions and / or shapes, in particular by uniform flanges for establishing a connection to other modules.

[0061] The modules can be connected to each other, at least in part, only at a final installation site, which is the location where the melting furnace is used. This facilitates the transport of the melting furnace to the installation site. In particular, the modules can have dimensions suitable for common truck or shipping container loading volumes to facilitate their transport. For example, the modules can have a cross-sectional area, as the product of a width and a height, of less than 12 m 2 for road transport or less than 7.2 m 2 for transport by sea containers.

[0062] Each module can comprise a furnace housing, in particular made of steel. Each module can be refractory lined or, in other words, refractorily lined. This lining is preferably carried out, for cost reasons, before the module is erected at the melting furnace installation site and / or before the module is installed to manufacture a melting furnace. For example, already cured linings can be installed in the modules or cured or dried in the modules before these modules are erected and connected to one another at the melting furnace installation site. This reduces the heating required for the melting furnace during an initial start-up phase at the installation site. Alternatively, the modules can be refractorily lined at the installation site, for example with a cured or uncured lining.The refractory linings of interconnected modules can also be connected to each other and / or supplemented to form a continuous lining.

[0063] The modules can be flexibly combined to form a melting furnace, for example, taking into account the desired capacity of the melting furnace. Thus, in principle, several different melting furnaces can be produced from a group of modules by selecting and combining the modules. This reduces the manufacturing costs of each melting furnace. As explained below, providing at least two modules offers particular advantages regarding reduced transport costs. A larger number of modules, in particular at least four, allows the modules to be arranged and connected in different ways to produce different layouts of a melting furnace. For example, a module sequence can be varied along the metal flow axis to create different layouts.

[0064] Accordingly, according to an advantageous embodiment, the modules can be used in different layouts or designs of a melting furnace or, in other words, can be assembled and connected according to such different layouts or designs. In other words: the modules are preferably configured such that different properties and / or capabilities of the melting furnace can be achieved through different combinations or different sequences of the modules. For example, by varying the number of modules, different furnace sizes or different furnace capacities can be produced with limited effort. For example, the melting performance of the melting furnace can be varied by varying the number of modules in which immersion heating elements are arranged. For example, by varying the modules with a charging area, the melting furnace can be easily adapted to the metal to be melted.

[0065] The melting furnace can be constructed entirely from modules of the type disclosed herein. A module can be configured according to any of the following examples, and a melting furnace can comprise any combination and number of modules according to the following examples: module with circulation pump; module with feed opening; module with opening for skimming the melt surface (comparable to or comprising a contaminant collection chamber disclosed herein); module with immersion heating elements; module for molten metal removal. According to one embodiment, the melting furnace comprises at least one module according to the examples listed above, but in particular the module with an opening for skimming the melt surface can be omitted. Furthermore, instead of a separate module for molten metal removal, a module, which preferably defines a portion of an annular channel disclosed herein, can comprise a conventional tapping valve.In principle, a module can also embody or comprise two of these examples, for example, by comprising both a circulation pump and immersion heating elements. According to a further development, the following applies to the dimensions of each module or at least a majority of the modules:

[0066] - the height is less than or equal to 2.9 m (in particular for transport in a sea container) or the height is less than or equal to 3.8 m (in particular for road transport); and / or

[0067] - at least one first (e.g. shorter) horizontal dimension is less than or equal to 2.5 m (in particular for transport in a sea container) or is less than or equal to 3 m (in particular for road transport); and / or

[0068] - at least one second (e.g. longer) horizontal dimension is less than or equal to 6 m or is less than or equal to 13.6 m.

[0069] The first horizontal dimension may be, for example, a width and / or the second horizontal dimension may be, for example, a length. The first and second horizontal dimensions may be substantially or completely orthogonal to each other.

[0070] For example, a module with an opening for receiving rejected components or recycled material from a molding process for remelting may be larger than several or all other modules. This module may be dimensioned for road transport and / or may approach or exceed the upper limits defined above (and / or, in particular, exceed the lower limits). All other modules, however, may at best approach the lower limits defined above.

[0071] The modules can have a connecting area at the at least one inlet opening and / or at the at least one outlet opening, by means of which they can be connected to any other module. This connecting area can, for example, comprise a flange or interface area of ​​the type discussed above. This can be provided in particular in the context of variants in which, in the manner described above, the modules each comprise a furnace housing with a refractory lining.

[0072] In a simple case, the melting furnace comprises only two modules, within which the melt nevertheless circulates in a ring channel formed by the modules. Each module has a connecting area, e.g. a flange, at its inlet and outlet openings. The flanges are preferably located on the long side of the modules (e.g. a comparatively longer or longest outer side of the modules), so that the modules are only about half as wide for transport as the melting furnace after the modules are connected at the installation site. The width of the modules is then, for example, less than the aforementioned 2.5 m for transport in sea containers, while the melting furnace assembled from the modules is wider than 2.5 m.

[0073] With this melting furnace, the melting furnace can be easily enlarged or expanded by adding additional modules between the two modules described above. For example, the melting capacity of the melting furnace can be increased by adding one module each with immersion heating elements. The melting capacity can be increased as required by adding additional modules with immersion heating elements.

[0074] In a further development, the circulation device comprises a mechanical or an electromagnetic pump and the molten metal flow flows from a pressure side to a suction side of the pump as part of its circulation.

[0075] According to a further embodiment, the heating device is arranged in a section of the annular channel in which a substantially complete volume exchange of the molten metal occurs as a result of the molten metal flow. This volume exchange preferably occurs continuously, in particular by correspondingly continuous flow through said section. In other words, no volume portions of the molten metal flow can remain permanently in this section and / or flow through this section at a significantly reduced speed (for example, at a speed of less than half a maximum flow speed of the molten metal flow in this section). The molten metal can flow continuously and completely through the section with the heating device, so that a correspondingly high volume of the molten metal is heated by the heating device.In particular, the section comprising the heating device can be free of projections directed toward a channel center and / or free of undercuts. Such shape features could otherwise impede the preferably complete melt exchange during flow through this section.

[0076] Additionally or alternatively, in the section comprising the heating device (and / or immediately upstream of this section), the molten metal flow can have a substantially uniform (or constant) flow velocity in the cross-section. In particular, a velocity profile within this cross-section can exhibit deviations between a maximum and minimum velocity of no more than 25%. Areas of direct contact between the molten metal and the inner walls of the melting furnace and / or the annular channel cannot be considered.

[0077] According to a further embodiment, the heating device comprises a plurality of immersion heating elements, wherein each immersion heating element is arranged at least partially outside the flow shadow of at least one corresponding other immersion heating element (or of the at least one other immersion heating element). In particular, each immersion heating element can be arranged at least outside a direct flow shadow of at least one or all of the other immersion heating elements.

[0078] The flow shadow of an immersion heating element can form or comprise an area into which molten metal cannot reach without being deflected by the immersion heating element (in particular, deflected along its outer side). Viewed along a flow direction of the molten metal flow impinging on an immersion heating element, the flow shadow can be arranged at a rear side of the immersion heating element. The molten metal flow, however, can impinge on the immersion heating element at a front side. The flow shadow can comprise a virtual extension of a flow axis of the molten metal flow impinging on the immersion heating element, wherein this extension intersects the immersion heating element.

[0079] At least half, at least two-thirds, and preferably the entire surface of each immersion heating element immersed in the molten metal can lie outside the aforementioned flow shadow. In order to be arranged outside the flow shadow of another immersion heating element, an immersion heating element (preferably each immersion heating element) can be offset transversely to the flow direction of the molten metal flow relative to the corresponding other immersion heating element, in particular at least partially or completely.

[0080] According to a further development, the melting furnace comprises at least one second heating device, which is positioned or positionable outside the molten metal. The second heating device is preferably designed to supply heat to the molten metal and / or a metal to be melted. In the latter case, for the purpose of this heat supply, it can be positioned close to and in particular vertically higher than a charging opening or an optional charging area described below, which can in particular be designed as a charging ramp. However, it can be positioned at a horizontal distance from the charging opening and, in particular, behind the charging opening, viewed in the direction of flow. Alternatively, it can be positioned directly opposite and above the optional charging ramp.

[0081] The provision of a second heating device can improve the efficiency of the melting furnace. This allows the molten metal to be heated when it is located away from the at least one immersion heating element. Excessive cooling of the molten metal, in particular the circulating metal, after optionally flowing around the immersion heating element can thus be prevented, which enables a lower-power design and / or lower-power operation of the immersion heating element. The second heating device can be arranged in a furnace area that is required for furnace operation anyway, but in which the provision of immersion heating elements is not necessarily preferred, for example, near a charging opening.

[0082] The first and second heating devices can be spaced apart from each other along the flow path of the molten metal. The first heating device can, for example, be configured to generate sufficient heat to melt the metal. The second heating device, however, may not be configured to generate such high heat. Instead, it can generate less heat, which is nevertheless sufficient to keep the molten metal warm (in particular, to keep it molten).

[0083] The first and second heating devices can be generically different, for example based on different operating principles for heat generation and / or heat transfer. In particular, the first heating device and the second heating device can be configured to generate heat independently of one another. Additionally or alternatively, they can be controllable and / or operated independently of one another with regard to their respective heat generation. According to one variant, the second heating device and the first heating device comprise heat sources that can be operated independently of one another. Optionally, both the first and the second heating devices can be electrically operated or, in other words, convert electrical energy into heat energy. Preferably, the first heating device transfers at least 50% of the energy required for melting into the metal, and preferably more than this 50%.In contrast, the second heating device preferably transfers less than 50% of the energy required for melting.

[0084] In particular, the second heating device can be designed as a radiant heater and furthermore in particular as a ceiling heater (or ceiling radiant heater) or at least comprise such a heater. This heater can be located opposite the molten metal and / or directed towards it. The radiant heater can be electrically operated. The ceiling heater can be arranged in a ceiling region of the melting furnace, in particular on an inner ceiling extending substantially parallel to the molten metal. The ceiling region can be fixed or, in other words, cannot be opened.

[0085] In general, the heating device can comprise at least one heating element that irradiates the surface of the molten metal from above and thereby heats it, in particular wherein more than 50% of the heat transfer into or onto the melt occurs through radiation. According to one variant, the heating element is elongated and / or rod-shaped and / or cylindrical. For example, it can be a SiC heating rod arranged horizontally and / or parallel to the surface of the molten metal. If there are a plurality of heating elements, and in particular heating rods, these can be arranged in a common plane. This plane can in turn run horizontally and / or parallel to the surface of the molten metal.

[0086] Alternatively, the second heating device can comprise at least one gas burner. This can be configured and positioned, in particular, to heat a still-solid metal in a charging area, or to heat the molten metal. A plurality of second heating devices can also be provided, although these heating devices can also differ from one another. For example, the melting furnace can comprise both a radiant heater (in particular a ceiling heater) and a gas burner.

[0087] The radiant heater can enable efficient continuous operation and, in particular, help maintain the molten metal at a desired temperature. A gas burner can enable particularly rapid heating of solid metal before it is added to the molten metal, but can also reliably heat existing molten metal. According to one variant, the second heating device is arranged vertically higher than the immersion heating element. This enables reliable heating of the molten metal without the second heating device having to be immersed in it. In particular, the second heating device can be arranged vertically above a maximum possible fill level.

[0088] In one embodiment, the second heating device is arranged at least at the same vertical height as, or vertically higher than, a charging opening, and in particular than any charging opening of the melting furnace. This ensures particularly reliable positioning of the second heating device outside the molten metal.

[0089] According to a further aspect, the circulation device, as already mentioned above, comprises a mechanical or electromagnetic pump or, alternatively, a magnetic or electromagnetic stirrer. The magnetic or electromagnetic stirrer can be arranged outside the melting furnace and / or a housing or furnace chamber. At least a part of the stirrer (e.g., a magnetic or electromagnetic drive device) can be arranged, for example, below a furnace chamber or furnace housing.

[0090] An alternative or additional embodiment provides that the circulation device comprises a mechanically driven stirrer, for example, a mechanical pump. In this case, for example, a stirring element extending into the melt can be rotated by mechanical coupling to a drive motor.

[0091] A preferred circulation device is a mechanical or electromagnetic pump.

[0092] A further development provides that the second heating device and the first heating device are arranged in different furnace chambers. As explained above, these different furnace chambers can be separated, for example, by at least one wall, another furnace chamber, or another area through which air can flow or around which air can flow. Preferably, the furnace chamber (hereinafter also referred to as the first furnace chamber) that has the first heating device has a smaller (e.g., average or maximum) flow cross-section than the other furnace chamber (hereinafter also referred to as the second furnace chamber) that has the second heating device. For example, the (e.g., average or maximum) flow cross-section of the first furnace chamber can be no more than 80% or no more than 50% of the (e.g., average or maximum) flow cross-section of the second furnace chamber.This allows a desired flow around the at least one immersion heating element to be achieved. On the other hand, the surface area of ​​the molten metal in the second furnace chamber can be specifically enlarged for effective heat transfer by the second heating device, which is positioned outside the melt.

[0093] According to one aspect, the second heating device is arranged in a (second) furnace chamber of the melting furnace, which has a charging opening for supplying metal to be melted. This can be the only charging opening of the melting furnace or one of a plurality of charging openings of the melting furnace. In the latter case, it is preferably not the smallest charging opening of the melting furnace, but rather, for example, the largest or at least an above-average size.

[0094] This allows comparatively large metal parts to be melted to be fed into the second furnace chamber and melted there before they reach the immersion heating element in the other (first) furnace chamber. This reduces the risk of collision between solid metal parts and the immersion heating element.

[0095] According to one aspect, the second furnace chamber has a loading opening that is larger than the first loading opening or than the loading opening in the first furnace chamber.

[0096] In general, the cross-section of the inflow area to the furnace chamber containing the second heating device can be smaller than the cross-section of the outflow area of ​​this furnace chamber. This allows flow velocities near the inlet area to be increased, allowing the flow to flow particularly comprehensively around solid metal parts there, with high heat transfer per unit time.

[0097] Furthermore, the inflow area of ​​the furnace chamber comprising the second heating device can be closer to the charging opening of this furnace chamber (herein also referred to as the second charging opening) than the outflow area of ​​this chamber. This proximity can be measured along a flow path and in particular as a distance along this flow path. This can also ensure that supplied metal parts are exposed to high flow velocities and are melted accordingly quickly. In this context, it can further be provided that the (first) furnace chamber in which the first heating device is arranged has a smaller charging opening than the charging opening of the furnace chamber (second furnace chamber) in which the second heating device is arranged.Both furnace chambers can therefore have loading openings, but the furnace chamber with the first heating device can have a small one, so that, for example, only small metal parts can be fed there. This also contributes to reducing the risk of damage to the immersion heating element from solid metal. In particular, the opening cross-section of the loading opening in the first furnace chamber can be less than half the size, less than a tenth, or less than a hundredth of the opening cross-section of the loading opening in the second furnace chamber.

[0098] A further development provides that the molten metal flow can be generated (e.g., by appropriate positioning and / or alignment of the circulation device) such that it flows from an outflow region of the (first) furnace chamber, which has the first heating device, toward an inflow region of the (second) furnace chamber, which has the second heating device. Furthermore, it can flow from an outflow region of the second furnace chamber toward an inflow region of the first furnace chamber. This represents an advantageous circulation direction for the molten metal flow to ensure effective melting of metal with a low risk of damage to the immersion heating element due to collisions with solid components.

[0099] In general, the circulation device can draw molten metal from the first furnace chamber and convey it into the second furnace chamber. Alternatively, the circulation device can draw molten metal from the second furnace chamber and convey it into the first furnace chamber.

[0100] In one embodiment, the circulation device is positioned near an inflow region of the furnace chamber which has the second heating device, and / or opens into this inflow region, in particular wherein the circulation device is positioned outside the furnace chamber which has the second heating device. As a result, solid metal fed into the second furnace chamber can be flowed around at high pressures and / or high velocities, which enables rapid melting. On the other hand, the risk of the circulation device circulating molten metal containing solid components can be reduced, which reduces a corresponding risk of damage to the circulation device. In principle, it can be provided that solid metal fed into the first furnace chamber can also be flowed around at high pressures.

[0101] According to one embodiment, the circulation device is arranged in the furnace chamber containing the first heating device. However, it can also be positioned outside of this chamber, for example, in a separate furnace chamber, but preferably not in the furnace chamber with the second heating device.

[0102] A further variant provides for the molten metal flow to be generated in such a way that it flows from the first heating device toward the circulation device and from the circulation device toward the second heating device. This can support the melting of solid components in the molten metal kept warm by the second heating device before they reach the first heating device.

[0103] A further variant provides for the molten metal flow to be generated in such a way that it flows from the first heating device toward the circulation device and from the circulation device toward a charging opening of the second furnace chamber (second charging opening). This can support the melting of solid components in the furnace chamber with the second charging opening and, due to convective heat transfer, make the second heating device unnecessary.

[0104] The melting furnace can have at least one impurity collection chamber through which the molten metal flow can flow, within which impurities contained in the molten metal can be collected. Furthermore, the impurity collection chamber can allow the collected impurities to be removed or drained, in particular via an open top, an openable lid, an openable door, or a drain valve. According to one variant, the impurity collection chamber comprises, for example, an outlet valve that can be opened to allow impurities deposited in the bottom area to flow away (or drain away).

[0105] The impurity collection chamber can be positioned, viewed along the molten metal flow direction, between the second furnace chamber, which comprises the second heating device and / or a second charging opening, and the first furnace chamber, which comprises the first heating device. In melting furnaces with a charging opening, the impurity collection chamber is preferably arranged downstream of the charging opening and / or its charging area, viewed along the flow path (in particular, closer to the charging opening, viewed along the flow path, than to the nearest of the first and second heating devices, viewed in the flow direction).In melting furnaces with several charging openings, the impurity collection chamber is preferably arranged - viewed in the direction of flow and in particular starting from the first heating device - after one or more of these charging openings and / or their charging areas (in particular, viewed along the flow path, closer to the charging opening than to the nearest of the first and second heating devices viewed in the direction of flow).

[0106] In particular, the contaminant collection chamber can be flowed through by a volume of molten metal before it enters the first furnace chamber. Thus, contaminants can be retained within the contaminant collection chamber before they can adhere to the immersion heating elements or otherwise damage them.

[0107] Additionally or alternatively, the contaminant collection chamber may have an inflow area and an outflow area, and a bottom area (or, in other words, a vertically recessed area or even a bottom depression) that is at least lower than the outflow area for collecting contaminants that settle there. Contaminants in the inflowing molten metal can thus sink into the bottom depression, particularly since this depression can cause a local reduction in the flow velocity.

[0108] The inflow region may have an opening cross-section extending to a bottom region of a furnace chamber located upstream of the contaminant collection chamber. This furnace chamber may, for example, be the first or second furnace chamber.

[0109] Alternatively, the contaminant collection chamber may have a device (for example, in the form of a surface weir) for collecting contaminants floating on or near the surface. This device may be comb-like, filter-like, and / or step-like, and may be designed to allow the molten metal to flow over or through it. The device may generally be designed to retain contaminants floating on or near the surface. These can then be removed by the device and thus from the melting furnace.

[0110] A contaminant collection chamber for collecting contaminants floating on or near the surface may have an inflow area and an outflow area, with the outflow area positioned lower than the inflow area in a vertical spatial direction. This can cause the contaminants to float on the surface within the contaminant collection chamber over as large an area as possible and for as long a period of time, and thus can be collected and removed with correspondingly increased reliability.

[0111] Consequently, one embodiment provides that the contaminant collection chamber has an outflow area with an opening cross-section, wherein an upper edge of the opening cross-section is lower than a minimum permissible level (k-min) of the molten metal in a furnace chamber located upstream relative to the contaminant collection chamber (in particular directly). Furthermore, the inflow area can have an opening cross-section whose upper edge is higher than a maximum permissible level (k-max) of the molten metal in said upstream chamber.

[0112] To ensure an effective cleaning function, any contaminant collection chamber may have its inflow area located closer to a feed opening than its outflow area.

[0113] In one embodiment, the melting furnace comprises a first impurity collection chamber of the type described above with a recessed bottom region for collecting impurities floating in the molten metal. Furthermore, this melting furnace also comprises an impurity collection chamber for collecting impurities of the type described above floating on the surface. The molten metal flow can preferably flow through the first and second impurity collection chambers successively. This enables particularly reliable cleaning of the molten metal. Alternatively, the two embodiments of the impurity collection chambers are combined in one chamber. In particular, these two impurity collection chambers can be positioned between the second and the first furnace chambers, viewed along the flow direction.

[0114] In a further embodiment, the melting furnace has a charging area that is positioned or positionable outside the molten metal and is configured to receive metal to be melted, in particular wherein the charging area is inclined in a ramp-like manner, for example vertically downwards and / or towards a floor region of the melting furnace and / or towards the receivable molten metal. The charging area can be adjacent to a charging opening and / or be accessible via the latter. Metal to be melted can be supplied via the charging opening and deposited, for example, in the charging area. There, it can heat up due to its proximity to the molten metal and the generally higher temperature inside the furnace compared to the surroundings. As disclosed herein, targeted heating can also be carried out by means of the second heating device or another heating device.Preheating the solid metal accelerates its subsequent melting.

[0115] Accordingly, it can generally be provided that the melting furnace is configured to heat metal received in the charging area before it enters the melt. This can be achieved, in particular, by supplying heated air from another area of ​​the furnace, wherein the other area is positioned, for example, near the second heating device, particularly if this is designed as a ceiling radiator above the molten metal, or by means of a gas burner directed at the charging area or an electrically operated heating device (for example, a radiant heater).

[0116] To direct heated air within the furnace, particularly in the manner described above toward a loading area, a device for circulating the furnace atmosphere may be provided. This device may comprise, for example, a blower or a fan.

[0117] A further development provides that the circulation device (for example, viewed along the molten metal flow) is positioned near a charging opening and / or a charging area (for example, closer to this than to the first heating device), wherein the charging opening and / or the charging area can in particular be encompassed by the first or second furnace chamber of the type disclosed herein. For example, the circulation device can be no more than 2 m or no more than 1 m away from the charging opening and / or the charging area, viewed along the molten metal flow. This increases the flow velocity of the molten metal near the charging opening and / or the charging area. Liquid melt therefore flows around the supplied solid metal at a higher velocity, which enables a higher heat input into the solid metal per unit time.

[0118] According to one variant, the melting furnace can be designed as follows: A first furnace chamber comprises the first heating device and a pump as a circulation device, each immersed in the melt. The immersion heating elements of the first heating device are arranged so that the melt flows around them. Optionally, a comparatively small charging opening is provided for adding (particularly small-piece) melt material to the melt, which is arranged so that the melt flows around the immersed melt material.

[0119] In a second furnace chamber through which the melt flows, the melt can be heated from above by means of a second heating device (e.g. comprising a radiant heater (in particular comprising at least one heating rod, a heating plate, a heating panel or a heating coil) or a gas burner). Furthermore, a comparatively large charging opening is provided here for adding, for example, large-piece melting material to the melt and is arranged such that the melt flows around the immersed melting material. The surface area of ​​the molten metal in the second furnace chamber is preferably larger than in the first furnace chamber to achieve effective heat transfer and / or to immerse large-piece melting material. The melt circulates between the furnace chambers under the influence of the circulating device. The circulating device can also be arranged along a flow path between the furnace chambers.

[0120] It should be noted that multiple circulation devices can also be provided, for example, each in a different furnace chamber. Multiple first and / or multiple second heating devices can also be provided in different furnace chambers. For example, multiple furnace chambers can be provided for multiple groups of immersion heating elements, with these furnace chambers being spatially separated and / or with at least one other furnace chamber without immersion heating elements located between them.

[0121] Furthermore, according to one aspect, a region with an at least temporary (or even section-wise) reduction in flow cross-section (of, for example, more than 20% compared to an upstream region) can be arranged upstream of a charging opening according to any type described herein (e.g., at a distance of less than 2 m or even less than 1 m along the flow path of the molten metal). Up to the charging opening, the flow cross-section can increase again, for example, to the size upstream of the aforementioned region with reduced flow cross-section. The region with reduced flow cross-section can be at least 20 cm and / or up to 1 m long. Due to the reduction in cross-section, molten material added through the charging opening can flow around it at an increased speed and thus experience a higher heat input per unit of time.In one variant, a plurality of, and in particular all, feed openings are preceded by an area with a corresponding reduction in flow cross-section.

[0122] A further development provides a lateral furnace pocket for filling the melting furnace with liquid metal. This can be understood as a furnace pocket arranged on a side wall of the furnace and / or laterally offset from at least one furnace chamber. This can be filled in the manner described above, in particular for the initial filling of molten metal into the melting furnace.

[0123] As also described above, the melting furnace can be configured for fill level detection or, in other words, melt level detection. For this purpose, it can have a control unit and a sensor configured to measure a level of the melt in the melting furnace (e.g., as a specific value) and / or to detect melt at a specific vertical height (in particular corresponding to a minimum permissible level or fill level) in a chamber of the melting furnace. The latter can comprise detecting the presence or absence of melt at this height, in particular in the form of a purely binary detection. Furthermore, the sensor can be configured to transmit a corresponding signal to the control unit, i.e., a signal indicating the measurement and / or detection result. The sensor can, for example, measure the distance to a melt surface.A further development of the melting furnace comprises at least one bottom weir at a bottom of the annular channel. When the furnace is emptied of melt, a residual amount up to a certain height can remain in the furnace for various reasons. After the heating devices of the furnace are switched off, this melt solidifies at the bottom. This causes a volume contraction. In a melting furnace having an annular channel, this contraction can lead to high pressures on the inner corners of the channel or on the refractory lining at these inner corners. The at least one bottom weir is preferably higher than an expected level of solidifying residual melt in the furnace. Therefore, it reduces the pressure on the refractory lining. For this purpose, the at least one bottom weir is positioned in the extension of a side wall of a channel such that an inner corner of the channel is no longer present at the bottom. Any bottom weirs can be positioned so that a (e.g.Solidified melt arranged between two bottom weirs (e.g., viewed along a flow axis) has an almost rectangular shape, especially when viewed from the bottom. Such a rectangular solidified metal plate can then be lifted upwards out of the channel using simple tools.

[0124] Geometrically, the bottom weir defines a height difference (in other words: a step) between the areas of the annular channel adjacent to the bottom weir on either side (particularly viewed in the direction of flow). The areas of the annular channel adjacent to either side can extend at an angle of more than 45° to each other, in particular at an angle of approximately 90°. Consequently, the bottom weir can be positioned in a deflection, bend, or corner area of ​​the annular channel (explained below), or can border an area in which the flow direction of the molten metal flow is not straight.

[0125] Due to the height difference, the bottom weir can reduce the height of a correspondingly curved or deflected wall surface of the annular channel along which the molten metal flow flows. This is particularly advantageous during solidification of the molten metal, which can lead to increased stresses on such non-rectilinear wall surfaces.

[0126] The bottom weir may have a maximum height above the bottom corresponding to at least 10%, and preferably between 15% and 40% (e.g., 20%), of a maximum fill level of the molten metal (e.g., a maximum fill level in the area of ​​the bottom weir or immediately upstream and / or downstream of it). This enables effective stress reduction without excessive reduction of the flow cross-section.

[0127] According to one variant, the bottom weir has a connecting channel, which is designed, for example, as a recess or groove and / or is located at the same level as the bottom of the adjacent areas of the annular channel and connects these areas to one another in a melt-conducting manner. This enables complete flow of the melt from an area upstream of the bottom weir to an area downstream of the bottom weir, for example, viewed in the flow direction of a circulating metal melt prior to flow.

[0128] In other words, a bottom weir can have a connecting channel approximately in its center between the adjacent areas of the annular channel, thus connecting these areas in a melt-conducting manner. When the furnace is emptied, the melt can flow through this connecting channel. This has the advantage that the residual liquid from both areas of the annular channel, namely from the areas before and after the bottom weir, can flow to a common point where it is removed from the furnace. This reduces the number of points where a device for removing the residual melt must be provided. The connecting channel can indeed form an inner corner in the annular channel, namely at the connecting channel. However, damage to this corner caused by contracting melt can be easily repaired with appropriate refractory materials and is generally less expensive to repair than damage to the inner corners of the annular channel side walls.

[0129] According to a further development, the melting furnace further comprises a furnace housing that delimits the annular channel (at least in sections), having at least one lid and a lid-lifting device configured to lift the lid to make the annular channel accessible. A lid-lifting device may comprise at least one actuator for lifting the lid. The at least one immersion heating element (or any plurality or all of the immersion heating elements) may be attached to the lid and may be liftable together with the lid. In the raised state, the immersion heating element may be positioned at least partially or completely outside the furnace housing, for example for maintenance purposes.

[0130] The lid can be lifted essentially vertically and / or linearly, as opposed to pivoting the lid. This allows heat radiation to be spatially limited to an area above the furnace casing, facilitating maintenance work.

[0131] The lid lifting device can be arranged on a side of the melting furnace facing the interior. Accordingly, the lid lifting device can be serviced from the interior.

[0132] According to a further development, the annular channel has at least one deflection region in which the flow direction of the molten metal flow is deflected by at least 45°, preferably by approximately 90°. The deflection region can form a corner region or curved region of the annular channel. In particular, it can connect two essentially rectilinear channel segments that extend at an angle to one another.

[0133] Side wall sections of the annular channel, which are arranged upstream and downstream of the deflection region in the direction of flow, can merge into one another in a rounded manner or be provided with a chamfer. In particular, these side wall sections can be encompassed by an inner side of the annular channel closer to the inner region of the melting furnace, thus forming inner side walls as opposed to outer side walls. The deflection region can therefore also be inner and / or define an inner deflection or an inner corner region. Alternatively or additionally, side wall sections which are encompassed by an outer side of the annular channel remote from the inner region of the melting furnace can merge into one another in a rounded manner or be provided with a chamfer. In other words, the annular channel and in particular its inner walls can have rounded or chamfered corner regions, for example in an above-mentioned deflection region.The provision of a chamfer can involve connecting two wall sections extending at a large angle, e.g., 90°, to each other by a particularly flat intermediate section that extends at a smaller angle to each of these wall sections. Thus, the deflection between the wall sections occurs with less sharp edges.

[0134] The rounded or chamfered transitions reduce stress peaks during any solidification of the molten metal. These stress peaks could otherwise damage the refractory lining of the melting furnace.

[0135] The invention also relates to a melting furnace for melting metal, including:

[0136] - a molten metal taken up in the melting furnace;

[0137] - a first heating device with at least one electrically heatable immersion heating element;

[0138] - a circulation device designed to generate a flow of molten metal flowing around the immersion heating element.

[0139] All features, developments and variants of a melting furnace and its features disclosed herein can also be provided in this melting furnace with accommodated molten metal.

[0140] Furthermore, the invention also relates to a method for melting metal by means of a melting furnace according to any aspect disclosed herein, the method comprising, inter alia:

[0141] - Generating the molten metal flow by means of the circulation device so that the molten metal flow flows around the immersion heating element.

[0142] The method may include all further steps and measures to provide any operating conditions, interactions, and functions of a melting furnace disclosed herein. For example, the method may also include the step of supplying metal to be melted via a charging opening, wherein the charging opening may be designed and arranged according to any variant described herein.

[0143] The invention also relates to a method for producing a melting furnace with an annular channel (for example, designed according to any aspect disclosed herein) in which a molten metal can be circulated, the method comprising: connecting individual modules to form at least a portion of the melting furnace, wherein each module comprises a channel segment of the annular channel and, in particular, an inflow opening and at least one outflow opening. The modules and the melting furnace can be designed according to any aspect disclosed herein. The modules can be selected and / or combined from a plurality of modules that can in principle be installed.

[0144] Exemplary embodiments are described in more detail with reference to the attached figures.

[0145] It shows

[0146] Figure 1 is a schematic representation of a melting furnace for melting metal.

[0147] Figure 2 is a schematic representation of a melting furnace for melting metal according to a further embodiment

[0148] Figure 2' is a schematic representation of a possible alternative arrangement of the immersion heating elements of Figure 2 in the melting furnace of Figure 2

[0149] Figure 2" is a schematic representation of a possible further alternative arrangement of the immersion heating elements of Figure 2 in the melting furnace of Figure 2

[0150] Figure 2'" is a schematic representation of a possible further alternative arrangement of the immersion heating elements of Figure 2 in the melting furnace of Figure 2

[0151] Figure 3 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment. Figure 4 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment.

[0152] Figure 5 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment

[0153] Figure 6 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment

[0154] Figure 6' the embodiment of Figure 6, wherein gas burners are provided as second heating elements instead of heating rods,

[0155] Figure 6" shows the embodiment of Figure 6, wherein both heating rods and gas burners are provided as second heating elements,

[0156] Figure 7 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment

[0157] Figure 8 is a schematic perspective view of a melting furnace

[0158] Figure 9 shows the melting furnace of Figure 8 in a section along a plane defined by the lines A and B shown in Figure 8

[0159] Figure 10 shows a section of Figures 8 and 9

[0160] Figure 11 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 10

[0161] Figure 12 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 11, wherein a loading ramp is provided,

[0162] Figure 13 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 12, wherein a loading ramp with gas burner is provided,

[0163] Figure 14 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 13, wherein a charging ramp and a gas circulation device are provided, Figure 15 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 14, wherein gas burners are provided instead of electrical heating elements,

[0164] Figure 16 is a schematic representation of a possible design of a melting furnace for melting metal according to a further embodiment,

[0165] Figure 17 is a sectional view of a melting furnace for melting metal according to another embodiment,

[0166] Figure 18 shows a subdivision of the melting furnace from Fig. 17 into individual modules,

[0167] Fig. 19 is a representation of a melting furnace according to a further embodiment with an annular melt channel and subdivision into two modules,

[0168] Fig. 20 is a representation of a melting furnace according to a further embodiment with an annular melt channel and subdivision into four modules,

[0169] Figure 21 is a view of an individual module of the melting furnace of Figs. 17 & 18, wherein the individual module includes a lid lifting device.

[0170] Figure 1 shows a schematic representation of a melting furnace 100 for melting metal. The melting furnace 100 is particularly suitable for melting metals with a melting point below 900°C.

[0171] The melting furnace comprises a first furnace chamber 110. The melting furnace 100 has a first charging opening 140. The charging opening 140 is configured to supply metal to be melted. The charging opening 140 is arranged on the furnace chamber 110 such that metal to be melted, hereinafter referred to as charging material, can be introduced from an environment 1 surrounding the melting furnace 100 through the charging opening 140 into the first furnace chamber when the charging opening is open. The charging opening 140 can be closed by a charging opening door 141. A furnace interior comprising the furnace chamber 110 can be closed from an environment surrounding the melting furnace, for example by the charging opening door 140. The furnace interior can comprise further furnace chambers and / or melt channels.In particular, regions of the melting furnace 100 that are designed to come into contact with molten metal are lined with refractory material. For example, the furnace chamber 110 is lined with refractory material. The refractory-lined regions, for example comprising the furnace chamber 110, are designed to withstand temperatures of up to 1600°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C (e.g., lead) and / or at least 420°C (e.g., zinc) and / or at least 600°C (e.g., aluminum alloy) and / or a maximum of 900°C (e.g., special aluminum alloy).

[0172] The melting furnace 100 is electrically heated. The melting furnace 100 comprises a first heating device 130 with an electrically heatable immersion heating element 131, which is arranged in the furnace chamber 110. The immersion heating element 131 is electrically driven to generate heat. The immersion heating element 131 has a refractory surface and can be immersed in molten metal to heat it. The furnace chamber 110 is at least partially filled with a molten metal 101, for example, molten aluminum. Molten aluminum comprises aluminum. Molten aluminum can, for example, be an aluminum alloy. Approximately 70% of the molten metal 101 arranged in the melting furnace 100 is located in the furnace chamber 110. The molten metal 101 flows around the immersion heating element 131. The molten metal 101 has a temperature of about 750° C.The melting furnace 100 includes a circulation device 120 configured to generate a molten metal flow, at least partially represented by arrows 101', within the melting furnace.

[0173] 120 comprises a pump 121 for conveying the molten metal 101. The circulation device 120 is arranged and configured such that the molten metal flow 101' between the immersion heating element 131 and the pump

[0174] 121 circulates. The pump 121 can be arranged in the furnace chamber 110 or outside the furnace chamber 110, wherein the illustration in Figure 1 outside the furnace chamber 110 is not restrictive. The pump 121 can be arranged in a second furnace chamber 111. Alternatively, the pump 121 can be fluidly connected to the furnace chamber 110 via melt channels. The melt channels are fireproof. The melt channels can be designed, at least in some regions, as closed tubes and / or at least in some regions as open channels. The melt channels can be heated. The pump 121 can be arranged next to the immersion heating element 131 in such a way that a suction port of the pump 121 is arranged facing away from the immersion heating element 131 and a pressure port of the pump 121 is arranged facing the immersion heating element 131.If the pump 121 is fluidly connected to the furnace chamber 110 via melt channels, a first melt channel fluidly connected to the furnace chamber 110 is fluidly connected to the suction port of the pump 121, and a second melt channel fluidly connected to the furnace chamber 110 is fluidly connected to the pressure port of the pump 121. The second melt channel can open into the furnace chamber 110 next to the immersion heating element 131, and the first melt channel can open into the furnace chamber 110 at a distance from the immersion heating element 131 such that the pump 121 can generate a melt flow that at least partially flows around the immersion heating element 131.

[0175] In particular, the circulation device 120 and the first heating device 130 are arranged such that the flow flows around the immersion heater in the form of the immersion heating element 131, wherein the convective heat transfer from the immersion heating element 131 to the molten metal in a flow area around the immersion heater is significantly higher (e.g., at least 20%, at least 50%, or at least 80% higher) than the heat transfer from the immersion heating element 131 to non-flowing molten metal of the same temperature and composition. The flow area is, in particular, a region in which the molten metal 101 has a velocity of at least 4 cm / s when the pump 121 is switched on and circulates the molten metal 101.

[0176] When pump 121 is switched on, the molten metal 101 flows from the discharge port of pump 121 to the intake port of pump 121. The molten metal 101 is thus sucked in by pump 121 and thereby circulated. The molten metal 101 flows through the furnace chamber 110 with the immersion heating element 131 and is thereby heated. If molten material has been introduced into the furnace chamber 110 via the charging opening 140, molten material is present in the furnace chamber 110. When pump 121 is switched on, the molten metal flows around the charging material in the furnace chamber 110 and heats it, causing it to melt.

[0177] It is thus evident that the molten metal circulates within the melting furnace 100. The flow path runs through a type of annular channel, which in particular encompasses all of the described furnace chambers and melt channels. Alternatively or additionally, further furnace chambers can be provided, each of which can in particular have a charging opening. The further furnace chambers can be designed and arranged such that the molten metal 101 is circulated by the pump 121 such that it flows through the further furnace chambers. Connecting channels and / or connecting openings between the furnace chambers can be designed such that charging material from one furnace chamber is not moved into a subsequent furnace chamber (in the direction of flow) or is only moved when a maximum size is reached. The further

[0178] Loading openings of the additional furnace chambers can be smaller than loading opening 140. The additional furnace chambers can also be suitable for receiving and melting loading material, for example in the form of metal chips. The furnace chamber 110 and the loading opening 140 can, in particular, be designed to receive larger loading material. The larger loading material can, for example, comprise metal objects, each having a maximum length and / or width of at least 30 cm and / or at least 40 cm and / or at least 50 cm. The larger loading material can, for example, comprise metal objects, each having a maximum length and / or width of at most 300 cm and / or at most 200 cm and / or at most 100 cm. The loading opening then has a length of 300 cm and a height of 200 cm or 200 cm x 150 cm or 100 cm x 100 cm.The small-piece load can, for example, comprise metal objects that can be introduced into the furnace through a loading opening that is a maximum of approximately 8 cm x 5 cm or approximately 60 cm x 60 cm in size.

[0179] The embodiment of Figure 1 can additionally have a second heating device (not shown in Figure 1, but explained below, for example, with reference to Figure 6). In particular, the second heating device can be arranged in the region of the second furnace chamber 111. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods, heating plates, heating panels, or heating coils. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 110, 111. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat so that the melt below the second heating elements is heated.

[0180] Figure 2 shows a schematic representation of a melting furnace 200 for melting metal. Figure 2 shows a plan view of the melting furnace 200 in a horizontal section through the melting furnace 200.

[0181] The melting furnace 200 is particularly suitable for melting metals with a melting point below 900 °C.

[0182] The melting furnace comprises a first furnace chamber 210 and a second furnace chamber 211. The first furnace chamber 210 and the second furnace chamber 211 are formed by furnace walls 212. A partition wall 212' separates the first furnace chamber 210 from the second furnace chamber 211. The first furnace chamber 210 and the second furnace chamber 211 are fluidly connected to one another via a first connecting opening 213 and a second connecting opening 214.

[0183] The melting furnace 200 has a first loading opening 240. The loading opening 240 is configured to supply metal to be melted. The loading opening 240 is arranged on the furnace chamber 211 such that metal to be melted, hereinafter referred to as the loading material, can be introduced from an environment 1 surrounding the melting furnace 200 through the loading opening 240 into the second furnace chamber 211 when the loading opening 240 is open. The loading opening 240 has a width of 120 cm and a height of 120 cm. The charging opening 240 can be closed by a charging opening door 241. A furnace interior, comprising the furnace chamber 210 and the second furnace chamber 211, can be closed by the charging opening door 240 from the environment 1 surrounding the melting furnace.

[0184] In particular, regions of the melting furnace 200 that are designed to come into contact with molten metal are lined with fireproof material. For example, the furnace chamber 210 and the furnace chamber 211 are, at least in some regions, lined with fireproof material. The fireproof-lined regions are designed to withstand temperatures of at least -50°C and / or at least -20°C and / or at least 0°C. The fireproof-lined regions are designed to withstand temperatures of up to 1500°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C and / or at least 420°C and / or at least 600°C and / or a maximum of 900°C. The melting furnace 200 is electrically heatable. The melting furnace 200 comprises a first heating device 230 with electrically heatable immersion heating elements 231 arranged in the furnace chamber 210.Preferably, five immersion heating elements 231 are arranged in the furnace chamber 210. The immersion heating elements 231 are electrically driven to generate heat. The immersion heating elements 231 have a refractory surface and can be immersed in molten metal to heat it.

[0185] Furnace chambers 210 and 211 are at least partially filled with molten metal 201, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 60% of the molten metal 201 arranged in the melting furnace 200 is located in the furnace chamber 211. About 40% of the molten metal 201 arranged in the melting furnace 200 is located in the furnace chamber 210. The molten metal 201 has a temperature of about 750°C.

[0186] The melting furnace 200 includes a circulation device 220 configured to generate a molten metal flow, at least partially represented by the arrows 201', within the melting furnace 200. The circulation device 220 includes a pump 221 for conveying the molten metal 201.

[0187] The circulation device 220 is arranged and configured such that the molten metal flow 201' circulates between the immersion heating elements 231 and the pump 221. The pump 221 is arranged in the first furnace chamber 210. An intake port of the pump 221 is sealingly connected to the first connection opening such that molten metal 201 flowing through the first connection opening flows into the pump 221. A discharge port of the pump 221 is arranged facing the immersion heating elements 231. The second connection opening is arranged downstream behind the immersion heating elements 231 such that the molten metal 201 conveyed by the pump 221 flows through the first furnace chamber 210, flowing around the immersion heating elements 231, and then flowing through the second connection opening into the second furnace chamber 211. As the immersion heating elements 231 flow around them, the molten metal 201 is heated.It is thus evident that the molten metal circulates within the melting furnace 100. The flow path runs through a kind of annular channel, which in particular encompasses all of the described furnace chambers.

[0188] For example, the immersion heating elements 231 can be arranged in a row in the direction of flow. Alternatively, one or more further rows of immersion heating elements 231 can be provided. The immersion heating elements 231 of a first row can be arranged exactly next to the immersion heating elements 231 of a second row. This is shown schematically in Figure 2', wherein the immersion heating elements 231 of the first row are shown in solid lines and the immersion heating elements 231 of the second row are shown in dashed lines. The immersion heating elements 231 of a first row can be arranged offset from the immersion heating elements 231 of a second row. This is shown schematically in Figure 2", wherein the immersion heating elements 231 of the first row are shown in solid lines and the immersion heating elements 231 of the second row are shown in dashed lines.

[0189] The immersion heating elements can be arranged offset in the flow direction. This can be done, in particular, such that they block the flow cross-section of the molten metal flow by more than 20%, as shown schematically in Figure 2.

[0190] When melting material 250 has been introduced into the furnace chamber 211 via the charging opening 240, the melting material 250 is located in the furnace chamber 211. When the pump 221 is switched on, the molten metal 201 flows around the melting material 250 located in the furnace chamber 211 and heats it, causing it to melt. The molten metal 201 flows from the connecting opening 214 through the second furnace chamber 211, flowing around the melting material 250 and flowing to the intake port of the pump 221, which is connected to the connecting opening 213.

[0191] Alternatively or in addition to a pump 221, the circulation device 220 can comprise a stirrer for circulating the molten metal. The stirrer can, for example, be arranged at least partially outside the furnace chambers and can be electromagnetic. At least part of the stirrer can, for example, be arranged below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 201 can be set into a rotational motion. Any stirrer mentioned in the context of the exemplary embodiments can be designed according to one of the above variants.

[0192] The embodiment of Figure 2 can additionally have a second heating device (not shown). In particular, the second heating device can be arranged in the region of the second furnace chamber 211. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods, heating plates, heating panels or heating coils. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 210, 211. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat, so that the melt below the second heating elements is heated.

[0193] Figure 3 shows a schematic representation of a melting furnace 300 for melting metal. Figure 3 shows a plan view of the melting furnace 300 in a horizontal section through the melting furnace 300.

[0194] The melting furnace 300 is particularly suitable for melting metals with a melting point below 900 °C. The melting furnace 300 is particularly suitable for melting lumpy feed material (melting material 350), for example, the size of a car rim.

[0195] The melting furnace comprises a first furnace chamber 310 and a second furnace chamber 311. The first furnace chamber 310 and the second furnace chamber 311 are formed by furnace walls 312. A partition wall 312' separates the first furnace chamber 310 from the second furnace chamber 311. The first furnace chamber

[0196] 310 and the second furnace chamber 311 are fluidly connected to each other via a first connecting opening 313 and a second connecting opening 314.

[0197] The melting furnace 300 has a first charging opening 340. The charging opening 340 is configured for supplying metal to be melted, in particular melting material 350, in this case, for example, a car rim. The charging opening 240 is arranged on the furnace chamber 311 such that the melting material 350 flows from an environment 1 surrounding the melting furnace 300 through the charging opening 340 into the second furnace chamber.

[0198] 311 when the charging opening 340 is open. The charging opening 340 has a width of 60 cm and a height of 60 cm. The charging opening 340 can be closed by a charging opening door 341. A furnace interior, comprising the furnace chamber 310 and the second furnace chamber 311, can be closed by the charging opening door 340 from the environment 1 surrounding the melting furnace.

[0199] In particular, regions of the melting furnace 300 that are designed to come into contact with molten metal are lined with refractory material. For example, the furnace chamber 310 and the furnace chamber 311 are lined with refractory material, at least in some regions. The refractory-lined regions are designed to withstand temperatures of up to 1500°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C and / or at least 420°C and / or at least 600°C and / or a maximum of 900°C.

[0200] The melting furnace 300 is electrically heated. The melting furnace 300 comprises a first heating device 330 with electrically heatable immersion heating elements 331 arranged in the furnace chamber 310. Preferably, six immersion heating elements 331 are arranged in the furnace chamber 310. The immersion heating elements 331 are electrically driven to generate heat. The immersion heating elements 331 have a refractory surface and can be immersed in molten metal to heat it.

[0201] Furnace chambers 310 and 311 are at least partially filled with molten metal 301, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 20% of the molten metal 301 located in the melting furnace 300 is located in the furnace chamber 311. About 80% of the molten metal 201 located in the melting furnace 300 is located in the furnace chamber 310. The molten metal 301 has a temperature of about 750°C.

[0202] The melting furnace 300 includes a circulation device 320 configured to generate a molten metal flow, at least partially represented by the arrows 301', within the melting furnace 300. The circulation device 320 includes a pump 321 for conveying the molten metal 301.

[0203] The circulation device 320 is arranged and configured such that the molten metal flow 301' circulates between the immersion heating elements 331 and the pump 321. The pump 321 is arranged in the first furnace chamber 310. A discharge port of the pump 321 is sealingly connected to the second connection opening 314 such that molten metal 301 flowing through the second connection opening first flows through the pump 321. An intake port of the pump 321 is arranged facing the immersion heating elements 331. The second connection opening 313 is arranged upstream of the immersion heating elements 231, so that the molten metal 301, which is conveyed by the pump 321, flows through the first furnace chamber 310, flows around the immersion heating elements 331, flows into the pump 321, and then flows through the second connection opening 314 into the second furnace chamber 311. Thus, it can be seen that the molten metal circulates within the melting furnace 100.The flow path runs through a kind of ring channel, which in particular encompasses all of the furnace chambers described.

[0204] As the immersion heating elements 331 flow around them, the molten metal 301 is heated. In particular, the immersion heating elements 331 can be arranged in three rows in the direction of flow. Alternatively, one or more further rows or just one or two rows of immersion heating elements 331 can be provided. The immersion heating elements 331 of a first row can be arranged offset from the immersion heating elements 331 of a second row. The immersion heating elements 331 of a first row can alternatively be arranged one behind the other or in alignment with the immersion heating elements 331 of a second row. This is shown schematically in Figure 3. Some immersion heating elements 331 can also be aligned with one another downstream, and some further immersion heating elements 331 can be arranged offset from one another downstream.

[0205] When melting material 350 has been introduced into the furnace chamber 311 via the charging opening 340, the melting material 350 is located in the furnace chamber 311. When the pump 321 is switched on, the molten metal 301 flows around the melting material 350 located in the furnace chamber 311 and heats it, causing it to melt. The molten metal 301 flows from the discharge port of the pump 331, from the connecting opening 314, through the second furnace chamber 311, flows around the melting material 350, and flows through the connecting opening 313, flows around the immersion heating elements 331 in the first furnace chamber 310, and flows to the intake port of the pump 321.

[0206] Alternatively or in addition to a pump 321, the circulation device 320 can have a stirrer for circulating the molten metal 301. The stirrer can be arranged, for example, outside the furnace chambers and can be electromagnetic. The stirrer can be arranged, for example, below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 301 can be set into a rotational motion.

[0207] The embodiment of Figure 3 can additionally have a second heating device (not shown). In particular, the second heating device can be arranged in the region of the second furnace chamber 311. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods, heating plates, heating panels or heating coils. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 310, 311. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat, so that the melt below the second heating elements is heated.

[0208] Figure 4 shows a schematic representation of a melting furnace 400 for melting metal. Figure 4 shows a plan view of the melting furnace 400 in a horizontal section through the melting furnace 400.

[0209] The melting furnace 400 is particularly suitable for melting metals with a melting point below 900 °C. The melting furnace 400 is particularly suitable for melting both melting material 450, for example in the form of metal chips, as well as lumpy feed material 450', for example, the size of a car rim.

[0210] The melting furnace comprises a first furnace chamber 410 and a second furnace chamber 411. The first furnace chamber 410 and the second furnace chamber 411 are formed by furnace walls 412. A partition wall 412' separates the first furnace chamber 410 from the second furnace chamber 411. The first furnace chamber 410 and the second furnace chamber 411 are fluidly connected to one another via a first connecting opening 413 and a second connecting opening 414.

[0211] The melting furnace 400 has a first loading opening 440. The loading opening 440 is configured to supply metal to be melted, in particular melting material 450, in this case, for example, metal chips. The loading opening 440 is arranged on the furnace chamber 411 such that the melting material 450 can be introduced from an environment 1 surrounding the melting furnace 400 through the loading opening 440 into the second furnace chamber 411 when the loading opening 440 is open. The loading opening 440 has a width of 40 cm and a height of 40 cm. The loading opening 440 can be closed by a loading opening door 441. The first charging opening 440 is arranged at a first end of the second furnace chamber 411 in the region of the second connecting opening 414. The melting furnace 400 has a second charging opening 440'.The loading opening 440' is configured to supply metal to be melted, in particular melting material 450', in this case, for example, a car rim. The loading opening 440' is arranged on the furnace chamber 411 such that the melting material 450' can be introduced from an environment 1 surrounding the melting furnace 400 through the loading opening 440' into the second furnace chamber 411 when the loading opening 440' is open. The loading opening 440' has a width of 60 cm and a height of 60 cm. The loading opening 440' can be closed by a loading opening door 441'. The second loading opening 440' is arranged at a second end of the second furnace chamber 411 in the region of the first connecting opening 413. A furnace interior, comprising the furnace chamber 410 and the second furnace chamber 411, can be closed off from the environment 1 surrounding the melting furnace 400 by the charging opening doors 440 and 440'.

[0212] In particular, regions of the melting furnace 400 that are designed to come into contact with molten metal are refractorily lined. For example, the furnace chamber 410 and the furnace chamber 411 are refractorily lined, at least in some regions. The refractorily lined regions are designed to withstand temperatures of up to 1500°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C and / or at least 420°C and / or at least 600°C and / or a maximum of 900°C.

[0213] The melting furnace 400 is electrically heated. The melting furnace 400 comprises a first heating device 430 with electrically heatable immersion heating elements 431 arranged in the furnace chamber 410. Preferably, six immersion heating elements 431 are arranged in the furnace chamber 410. The immersion heating elements 431 are electrically driven to generate heat. The immersion heating elements 431 have a refractory surface and can be immersed in molten metal to heat it.

[0214] Furnace chambers 410 and 411 are at least partially filled with molten metal 401, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 20% of the molten metal 401 arranged in the melting furnace 400 is located in the furnace chamber 411. About 80% of the molten metal 201 arranged in the melting furnace 400 is located in the furnace chamber 410. The molten metal 401 has a temperature of about 750°C.

[0215] The melting furnace 400 includes a circulation device 420 configured to generate a molten metal flow, at least partially represented by the arrows 401', within the melting furnace 400. The circulation device 420 includes a pump 421 for conveying the molten metal 401.

[0216] The circulation device 420 is arranged and configured such that the molten metal flow 401' circulates between the immersion heating elements 431 and the pump 421. The pump 431 is arranged in the first furnace chamber 410. A discharge port of the pump 421 is sealingly connected to the second connection opening 414 such that molten metal 401 flowing through the second connection opening first flows through the pump 421. An intake port of the pump 421 is arranged facing the immersion heating elements 431. The second connection opening 413 is arranged upstream of the immersion heating elements 231, so that the molten metal 401, which is conveyed by the pump 421, flows through the first furnace chamber 410, flows around the immersion heating elements 431, flows into the pump 421, and then flows through the second connection opening 414 into the second furnace chamber 411. As it flows around the immersion heating elements 431, the molten metal 401 is heated.It is thus evident that the molten metal circulates within the melting furnace 100. The flow path runs through a kind of annular channel, which in particular encompasses all of the described furnace chambers.

[0217] In particular, the immersion heating elements 431 can be arranged in three rows in the direction of flow. Alternatively, one or more further rows or just one or two rows of immersion heating elements 431 can be provided. The immersion heating elements 431 of a first row can be arranged offset from the immersion heating elements 431 of a second row. The immersion heating elements 431 of a first row can alternatively be arranged one behind the other or in alignment with the immersion heating elements 431 of a second row. This is shown schematically in Figure 4. Some immersion heating elements 431 can also be aligned with one another downstream, and some further immersion heating elements 431 can be arranged offset from one another downstream.

[0218] When melting material 450 has been introduced into the furnace chamber 411 via the charging opening 440, melting material 450 is located in the furnace chamber 411. When the pump 421 is switched on, the molten metal 401 flows around the melting material 450 located in the furnace chamber 411 and heats it so that it melts. The molten metal 401 flows from the pressure port of the pump 431 from the connection opening 414 through the second furnace chamber 411, first flows around the melting material 450, then the melting material 450' and flows through the connection opening 413, flows around the immersion heating elements 431 in the first furnace chamber 410 and flows to the intake port of the pump 421. The first feed opening 440 is arranged closer to the pressure port of the pump 421 than the second feed opening 440'.As a result, the melt material 450 is first flowed around and already partially melted, before the metal melt 401, now already partially encompassing the melt material 450, flows around the melt material 450' and at least partially melts it.

[0219] Alternatively or in addition to a pump 421, the circulation device 420 can have a stirrer for circulating the molten metal 401. The stirrer can be arranged, for example, outside the furnace chambers and can be electromagnetic. The stirrer can be arranged, for example, below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 401 can be set into a rotational motion.

[0220] The embodiment of Figure 4 can additionally have a second heating device (not shown). In particular, the second heating device can be arranged in the region of the second furnace chamber 411. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods, heating plates, heating panels or heating coils. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 410, 411. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat, so that the melt below the second heating elements is heated.

[0221] Figure 5 shows a schematic representation of a melting furnace 500 for melting metal. Figure 5 shows a plan view of the melting furnace 500 in a horizontal section through the melting furnace 500.

[0222] Melting furnace 500 is particularly suitable for melting metals with a melting point below 900°C. Melting furnace 500 is particularly suitable for melting lumpy feed material (melting material 550), for example, the size of a car rim. Furthermore, melting furnace 500 is suitable for simultaneously accommodating and melting several larger metal parts.

[0223] The melting furnace comprises a first furnace chamber 510 and a second furnace chamber 511. The first furnace chamber 510 and the second furnace chamber 511 are formed by furnace walls 512. A partition wall 512' separates the first furnace chamber 510 from the second furnace chamber 511. The first furnace chamber

[0224] 510 and the second furnace chamber 511 are fluidically connected to each other via a first connecting opening 513 and a second connecting opening 514.

[0225] The melting furnace 500 has a first charging opening 540. The charging opening 540 is configured for supplying metal to be melted, in particular, melting material 550, in this case, for example, a car rim. The charging opening 540 is arranged on the furnace chamber 511 such that the melting material 550 flows from an environment 1 surrounding the melting furnace 500 through the charging opening 540 into the second furnace chamber.

[0226] 511 when the loading opening 540 is open. The loading opening 540 has a width of 60 cm and a height of 60 cm. For example, a conveyor or a robot can be connected to the loading opening so that loading material can be automatically introduced into the melting furnace 500. The loading opening 540 can be closed by a loading opening door 541. A furnace interior, comprising the furnace chamber 510 and the second furnace chamber 511, can be closed by the loading opening door 541 from the environment 1 surrounding the melting furnace.

[0227] The melting furnace 500 has a second charging opening 540'. The charging opening 540' is configured to supply metal to be melted, in particular melting material 550', in this case, for example, a plurality of metal bars. The charging opening 540' is arranged on the furnace chamber 511 such that the melting material 550' can be introduced from an environment 1 surrounding the melting furnace 500 through the charging opening 540' into the second furnace chamber 511 when the charging opening 540' is open. The charging opening 540' has a width of 150 cm and a height of 120 cm. This has the advantage that larger quantities of charging material can be introduced into the second furnace chamber simultaneously. For example, the feed material can be tipped from a collection container through the feed opening 540'. The melt material 550' can, for example, be returns from a casting process.The melting furnace can have receiving devices for such a collecting container on an outer wall. For example, a conveyor or a robot can be connected to the charging opening so that charging material can be automatically introduced into the melting furnace 500. The charging opening 540' can be closed by a charging opening door 541'. A furnace interior, comprising the furnace chamber 510 and the second furnace chamber 511, can be closed from the environment 1 surrounding the melting furnace by the charging opening door 541'.

[0228] In particular, regions of the melting furnace 500 that are designed to come into contact with molten metal are lined with refractory material. For example, the furnace chamber 510 and the furnace chamber 511 are at least partially lined with refractory material. The refractory-lined regions are designed to withstand temperatures of at least -50°C and / or at least -20°C and / or at least 0°C. The refractory-lined regions are designed to withstand temperatures of up to 5000°C and / or up to 2000°C and / or up to 1500°C. For this purpose, a metal melt 501 located in the melting furnace 500, in particular in the furnace chambers 510 and 511, can be heated to temperatures of at least 500 °C and / or at least 700 °C and / or at least 900 °C and / or at least 1100 °C.

[0229] The melting furnace 500 is electrically heated. The melting furnace 500 comprises a first heating device 530 with electrically heatable immersion heating elements 531 arranged in the furnace chamber 510. Preferably, six immersion heating elements 531 are arranged in the furnace chamber 510. The immersion heating elements 531 are electrically driven to generate heat. The immersion heating elements 531 have a refractory surface and can be immersed in molten metal to heat it.

[0230] Furnace chambers 510 and 511 are at least partially filled with molten metal 501, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 20% of the molten metal 501 arranged in the melting furnace 500 is located in the furnace chamber 511. About 80% of the molten metal 201 arranged in the melting furnace 500 is located in the furnace chamber 510. The molten metal 501 has a temperature of about 750°C.

[0231] The melting furnace 500 comprises a circulation device 520 configured to generate a molten metal flow, at least partially represented by the arrows 501', within the melting furnace 500. The circulation device 520 comprises a pump 521 for conveying the molten metal 501. The circulation device 520 is arranged and configured such that the molten metal flow 501' circulates between the immersion heating elements 531 and the pump 521. The pump 521 is arranged in the first furnace chamber 510. A pressure port of the pump 521 is sealingly connected to the second connection opening 514 such that molten metal 501 flowing through the second connection opening first flows through the pump 521. An intake port of the pump 521 is arranged facing the immersion heating elements 531.The second connection opening 513 is arranged upstream of the immersion heating elements 531, so that the molten metal 501, which is conveyed by the pump 521, flows through the first furnace chamber 510, flows around the immersion heating elements 531, flows into the pump 521, and then flows through the second connection opening 514 into the second furnace chamber 511. It can thus be seen that the molten metal circulates within the melting furnace 100. The flow path runs through a type of annular channel, which in particular encompasses all of the described furnace chambers.

[0232] As the immersion heating elements 531 flow around them, the molten metal 501 is heated. In particular, the immersion heating elements 531 can be arranged in three rows in the direction of flow. Alternatively, one or more further rows or just one or two rows of immersion heating elements 531 can be provided. The immersion heating elements 531 of a first row can be arranged offset from the immersion heating elements 531 of a second row. The immersion heating elements 531 of a first row can alternatively be arranged one behind the other or in alignment with the immersion heating elements 531 of a second row. This is shown schematically in Figure 5. Some immersion heating elements 531 can also be aligned with one another downstream, and some further immersion heating elements 531 can be arranged offset from one another downstream.

[0233] When molten material 550 has been introduced into the furnace chamber 511 via the charging opening 540, the molten material 550 is located in the furnace chamber 511. When the pump 521 is switched on, the molten metal 501 flows around the molten material 550 located in the furnace chamber 511 and heats it so that it melts. The molten metal 501 flows from the pressure port of the pump 531 from the connecting opening 514 through the second furnace chamber 511, first flowing around the molten material 550 and then the molten material 550' and flowing through the connecting opening 513, flowing around the immersion heating elements 531 in the first furnace chamber 510 and flowing to the intake port of the pump 521. Alternatively or in addition to a pump 521, the circulating device 520 can have a stirrer for circulating the molten metal 501. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. The stirrer can, for example, be located below the furnace chambers.By applying an alternating electromagnetic field, the molten metal 501 can be set into a rotational movement.

[0234] The embodiment of Figure 5 can additionally have a second heating device (not shown). In particular, the second heating device can be arranged in the region of the second furnace chamber 511. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods, heating plates, heating panels or heating coils. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 510, 511. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat, so that the melt below the second heating elements is heated.

[0235] Figure 6 shows a schematic representation of a melting furnace 600 for melting metal. Figure 6 shows a plan view of the melting furnace 600 in a horizontal section through the melting furnace 600.

[0236] The melting furnace 600 is particularly suitable for melting metals with a melting point below 1600 °C.

[0237] The melting furnace comprises a first furnace chamber 610 and a second furnace chamber 611. The first furnace chamber 610 and the second furnace chamber 611 are formed by furnace walls 612. A partition wall 612' separates the first furnace chamber 610 from the second furnace chamber 611. The first furnace chamber 610 and the second furnace chamber 611 are fluidly connected to one another via a first connecting opening 613 and a second connecting opening 614.

[0238] The melting furnace 600 has a first loading opening 640. The loading opening 640 is configured to supply metal to be melted. The loading opening 640 is arranged on the furnace chamber 611 such that metal to be melted can be introduced from an environment 1 surrounding the melting furnace 600 through the loading opening 640 into the second furnace chamber 611 when the loading opening 640 is open. The loading opening 640 has a width of 120 cm and a height of 120 cm. The charging opening 640 can be closed by a charging opening door 641. A furnace interior, comprising the furnace chamber 610 and the second furnace chamber 611, can be closed by the charging opening door 640 from the environment 1 surrounding the melting furnace.

[0239] In particular, regions of the melting furnace 600 that are designed to come into contact with molten metal are lined with refractory material. For example, the furnace chamber 610 and the furnace chamber 611 are lined with refractory material, at least in some regions. The refractory-lined regions are designed to withstand temperatures of at least -50°C and / or at least -20°C and / or at least 0°C. The refractory-lined regions are designed to withstand temperatures of up to 1500°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C and / or at least 420°C and / or at least 600°C and / or a maximum of 900°C.

[0240] The melting furnace 600 is electrically heated. The melting furnace 600 comprises a first heating device 630 with electrically heatable immersion heating elements 631 arranged in the furnace chamber 610. Preferably, five immersion heating elements 631 are arranged in the furnace chamber 610. The immersion heating elements 631 are electrically driven to generate heat. The immersion heating elements 631 have a refractory surface and can be immersed in molten metal to heat it.

[0241] Furnace chambers 610 and 611 are at least partially filled with molten metal 601, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 60% of the molten metal 601 arranged in the melting furnace 600 is located in the furnace chamber 611. About 40% of the molten metal 601 arranged in the melting furnace 600 is located in the furnace chamber 610. The molten metal 601 has a temperature of about 750°C.

[0242] The melting furnace 600 includes a circulation device 620 configured to generate a molten metal flow, at least partially represented by the arrows 601', within the melting furnace 600. The circulation device 620 includes a pump 621 for conveying the molten metal 601.

[0243] The circulation device 620 is arranged and configured such that the molten metal flow 601' circulates between the immersion heating elements 631 and the pump 621. The pump is arranged in the first furnace chamber 610. An intake port of the pump 621 is sealingly connected to the first connection opening such that molten metal 601 flowing through the first connection opening flows into the pump 621. A pressure port of the pump 621 is arranged facing the immersion heating elements 631. The second connection opening is arranged downstream behind the immersion heating elements 631 such that the molten metal 601 conveyed by the pump flows through the first furnace chamber, flowing around the immersion heating elements 631 and then flowing through the second connection opening 614 into the second furnace chamber 611. Thus, it can be seen that the molten metal circulates within the melting furnace 100.The flow path runs through a kind of ring channel, which in particular encompasses all of the furnace chambers described.

[0244] As the immersion heating elements flow around them, the molten metal 601 is heated. In particular, the immersion heating elements 631 can be arranged in a row in the direction of flow. Alternatively, one or more further rows of immersion heating elements 631 can be provided. In this case, the immersion heating elements 631 of a first row can be arranged exactly below the immersion heating elements 631 of a second row (analogous to the arrangement of the immersion heating elements 231 and as already described above with reference to Figure 2'). The immersion heating elements of a first row can be arranged offset from the immersion heating elements of a second row (analogous to the arrangement of the immersion heating elements 231 and as already described above with reference to Figure 2").

[0245] When molten material 650 has been introduced into the furnace chamber 611 via the charging opening 640, the molten material 650 is located in the furnace chamber 611. When the pump 621 is switched on, the molten metal 601 flows around the molten material 650 located in the furnace chamber 611 and heats it so that it melts. The molten metal 601 flows from the pump 631, driven by a pressure port of the pump, through the first furnace chamber 610, flows around the immersion heating elements 631, flows through the connecting opening 614 into the second furnace chamber 611, flows around the molten material 650, and flows to the intake port of the pump 621 connected to the connecting opening 613. Alternatively or in addition to a pump 621, the circulating device 620 can have a stirrer for circulating the molten metal. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. The stirrer can, for example, be located below the furnace chambers.By applying an alternating electromagnetic field, the molten metal 601 can be set into a rotational movement.

[0246] A second heating device 660 is arranged in the region of the second furnace chamber 611. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region in the furnace chamber 611 that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. In the exemplary embodiment shown in Figure 6, the second heating device 660 comprises second heating elements 661 in the form of heating rods, which are arranged under a ceiling of the second furnace chamber 611. The heating rods are electrically operated. When switched on, the heating rods radiate heat, so that the melt in the region of the second heating chamber 611 is heated.

[0247] Figure 6' corresponds to Figure 6, but instead of heating rods, gas burners are provided as second heating elements 661. Only one gas burner is shown as an example. However, a single or multiple gas burners may be provided. The underlying melt 601 can be heated via the gas burner. Figure 6" corresponds to Figure 6, but in addition to heating rods, gas burners are also provided as second heating elements 661.

[0248] The gas burner can be positioned closer to the charging opening 640 than the heating rods. This allows heat to be transferred from the gas flame to the area near the charging opening, where the melting material is located immediately after it has been charged. This accelerates the melting process. However, a reverse sequence (heating rods closer to the charging opening 640 than the gas burner) can also be provided.

[0249] Figure 7 shows a schematic representation of a melting furnace 700 for melting metal. Figure 7 shows a horizontal section through the melting furnace 700 in a top view.

[0250] The melting furnace 700 is particularly suitable for melting metals with a melting point below 900°C. The melting furnace 700 is particularly suitable for melting lumpy feed material (melting material 750), for example, the size of a car rim. Furthermore, the melting furnace 700 is suitable for simultaneously accommodating and melting several larger metal parts.

[0251] The melting furnace comprises a first furnace chamber 710 and a second furnace chamber 711. The first furnace chamber 710 and the second furnace chamber 711 are formed by furnace walls 712. A partition wall 712' separates the first furnace chamber 710 from the second furnace chamber 711. The first furnace chamber

[0252] 710 and the second furnace chamber 711 are fluidly connected to each other via a first connecting opening 713 and a second connecting opening 714.

[0253] The melting furnace 700 has a first charging opening 740. The charging opening 740 is configured for supplying metal to be melted, in particular, melting material 750, in this case, for example, a car rim. The charging opening 740 is arranged on the furnace chamber 711 such that the melting material 750 flows from an environment 1 surrounding the melting furnace 700 through the charging opening 740 into the second furnace chamber.

[0254] 711 when the loading opening 740 is open. The loading opening 740 has a width of 120 cm and a height of 120 cm. For example, a conveyor or a robot can be connected to the loading opening so that loading material can be automatically introduced into the melting furnace 700. The loading opening 740 can be closed by a loading opening door 741. A furnace interior, comprising the furnace chamber 710 and the second furnace chamber 711, can be closed by the loading opening door 740 from the environment 1 surrounding the melting furnace.

[0255] The melting furnace 700 has a second charging opening 740'. The charging opening 740' is configured to supply metal to be melted, in particular melting material 750', in this case, for example, a plurality of metal bars. The charging opening 740' is arranged on the furnace chamber 711 such that the melting material 750' can be introduced from an environment 1 surrounding the melting furnace 700 through the charging opening 740' into the second furnace chamber 711 when the charging opening 740' is open. The charging opening 740' has a width of 100 cm and a height of 100 cm. This has the advantage that larger quantities of charging material can be introduced into the second furnace chamber simultaneously. For example, the feed material can be tipped from a collection container through the feed opening 740'. The melt material 750' can, for example, be returns from a casting process.The melting furnace can have receiving devices for such a collecting container on an outer wall. For example, a conveyor or a robot can be connected to the charging opening so that charging material can be automatically introduced into the melting furnace 700. The charging opening 740' can be closed by a charging opening door 741'. A furnace interior, comprising the furnace chamber 710 and the second furnace chamber 711, can be closed from the environment 1 surrounding the melting furnace by the charging opening door 741'.

[0256] In particular, regions of the melting furnace 700 that are designed to come into contact with molten metal are lined with refractory material. For example, the furnace chamber 710 and the furnace chamber 711 are lined with refractory material, at least in some regions. The refractory-lined regions are designed to withstand temperatures of at least -50°C and / or at least -20°C and / or at least 0°C. The refractory-lined regions are designed to withstand temperatures of up to 1500°C and / or up to 1100°C and / or up to 600°C. For this purpose, a molten metal located in the melting furnace, in particular in the furnace chamber 110, can be heated to temperatures of at least 300°C and / or at least 420°C and / or at least 600°C and / or a maximum of 900°C.

[0257] The melting furnace 700 is electrically heated. The melting furnace 700 comprises a first heating device 730 with electrically heatable immersion heating elements 731 arranged in the furnace chamber 710. Preferably, six immersion heating elements 731 are arranged in the furnace chamber 710. The immersion heating elements 731 are electrically driven to generate heat. The immersion heating elements 731 have a refractory surface and can be immersed in molten metal to heat it.

[0258] Furnace chambers 710 and 711 are at least partially filled with molten metal 701, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 20% of the molten metal 701 arranged in the melting furnace 700 is located in the furnace chamber 711. About 80% of the molten metal 201 arranged in the melting furnace 700 is located in the furnace chamber 710. The molten metal 701 has a temperature of about 750°C.

[0259] The melting furnace 700 comprises a circulation device 720 configured to generate a molten metal flow, at least partially represented by the arrows 701', within the melting furnace 700. The circulation device 720 comprises a pump 721 for conveying the molten metal 701. The circulation device 720 is arranged and configured such that the molten metal flow 701' circulates between the immersion heating elements 731 and the pump 721. The pump 721 is arranged in the first furnace chamber 710. A pressure port of the pump 721 is sealingly connected to the second connection opening 714 such that molten metal 701 flowing through the second connection opening first flows through the pump 721. An intake port of the pump 721 is arranged facing the immersion heating elements 731.The second connection opening 713 is arranged upstream of the immersion heating elements 731, so that the molten metal 701, which is conveyed by the pump 721, flows through the first furnace chamber 710, flows around the immersion heating elements 731, flows into the pump 721, and then flows through the second connection opening 714 into the second furnace chamber 711. It can thus be seen that the molten metal circulates within the melting furnace 100. The flow path runs through a type of annular channel, which in particular encompasses all of the described furnace chambers.

[0260] As the water flows around the immersion heating elements 731, the molten metal 701 is heated. In particular, the immersion heating elements 731 can be arranged in three rows in the direction of flow. Alternatively, one or more further rows or just one or two rows of immersion heating elements 731 can be provided. The immersion heating elements 731 of a first row can be arranged offset from the immersion heating elements 731 of a second row. The immersion heating elements 731 of a first row can alternatively be arranged one behind the other or in alignment with the immersion heating elements 731 of a second row. This is shown schematically in Figure 7. Some immersion heating elements 731 can also be aligned with one another downstream, and some further immersion heating elements 731 can be arranged offset from one another downstream.

[0261] The charging opening 740 is located in the flow direction immediately behind the connecting opening 714. When molten material 750 has been introduced into the furnace chamber 711 via the charging opening 740, the molten material 750 is located in the furnace chamber 711. When the pump 721 is switched on, the molten metal 701 flows around the molten material 750 located in the furnace chamber 711 and heats it so that it melts. The molten metal 701 flows from the pressure port of the pump 731 from the connecting opening 714 into the second furnace chamber and initially flows around the melting material 750. The charging opening 740' is located in the flow direction behind the connecting opening 714 and behind the charging opening 740. After the molten metal 101 has flowed around the melting material 750, it flows around the melting material 750', which was introduced via the charging opening 740'.When flowing through the second furnace chamber 711, the molten metal 701 first flows around the melting material 750 and then the melting material 750' and then flows through the connecting opening 713, flows around the immersion heating elements 731 in the first furnace chamber 710 and flows to the intake port of the pump 721.

[0262] A second heating device 760 is arranged on a ceiling in a ceiling region of the second furnace chamber 711. The second heating device 760 is an electric heating device. The second heating device 760 is arranged in an area that does not come into contact with the melt, namely on a furnace chamber ceiling. The second heating device 760 is arranged above the melt. The second heating device comprises four second heating elements 761 in the form of heating rods. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged below a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 710, 711. When switched on, the heating elements 761 radiate heat, so that the melt 701 below the second heating elements 761 is heated. The heating elements 761 are arranged downstream behind the second charging opening 740'.

[0263] Alternatively or in addition to a pump 721, the circulation device 720 can have a stirrer for circulating the molten metal 701. The stirrer can be arranged, for example, outside the furnace chambers and can be electromagnetic. The stirrer can be arranged, for example, below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 701 can be set into a rotational motion.

[0264] Figure 8 shows a schematic, perspective view of a melting furnace 800, which is shown partially in section to illustrate a furnace interior. The melting furnace 800 can be filled with molten metal. The illustrated melting furnace 800 has a first furnace chamber 810, in which a first heating device 830 comprising immersion heating elements 831 is arranged. The immersion heating elements 831, one of which is provided with the reference numeral 831 by way of example, are electrical heating elements. A second furnace chamber 811 is provided, which is fluidically connected to the first furnace chamber 810. The melting furnace 800 comprises further furnace chambers 811', 811", and 811'", which are also fluidically connected to the first furnace chamber 810 and the second furnace chamber 811. A circulation device 820 is arranged in a furnace chamber 811', which is arranged upstream of the furnace chamber 811. The circulation device 820 comprises a pump 821. A pressure port (ieAn inlet port (i.e., a pressure side) of the pump 821 faces the furnace chamber 811, and an intake port (i.e., an intake side) of the pump 821 faces the furnace chamber 810. The pump 821 circulates a molten metal located inside the furnace, so that it is conveyed from the first furnace chamber into the furnace chamber 811' by the pump 821 and from there into the second furnace chamber 811, from where it flows again via a furnace chamber 811"' into the first furnace chamber 810. It can thus be seen that the molten metal circulates within the melting furnace 100. The flow path runs through a type of annular channel, which in particular encompasses all of the furnace chambers described.

[0265] The dimensions of the furnace chamber 810, 811, 811', 811", 811'" are exemplary. In particular, the furnace chamber 811 can be dimensioned smaller. In particular, it can only be dimensioned comparatively large if its loading opening 840 is designed to be sufficiently large for any return parts (ie, defective castings that are to be remelted).

[0266] A charging opening 840 for introducing melt material is provided on the second furnace chamber 811. The loading opening 840 is located in an upper half of a vertical height of the second furnace chamber 811. A second loading opening 840' is provided on a furnace chamber 811". The second loading opening 840' is smaller than the first loading opening 840. The first loading opening 840 is suitable for larger metal parts to be introduced, for example with a size of at least 40 cm and at most 300 cm, and the second loading opening 840' is suitable for bulk material, for example metal chips with a maximum length of, for example, a maximum of 10 cm and a maximum minimum length of 0.5 mm. The furnace chamber 811'", which is arranged in the flow direction between the second furnace chamber 811 and the first furnace chamber 810, is designed as a contaminant collection chamber.An opening (not shown) for connecting a tapping valve is provided on the furnace chamber in the region of the lower recess. A second heating device 860 is arranged on a ceiling in the second furnace chamber 811. The heating device comprises heating elements 861, which are designed as electric heating rods. Additionally or alternatively, the heating rods can also be designed as gas burners. The melting furnace further comprises a removal pocket 811'. v which is arranged on the chamber 811' and fluidically connected thereto. Furthermore, a cleaning opening 870 (see Fig. 11) is provided on the furnace chamber 811. The cleaning opening 870 and the charging openings 840 and 840' each have a cover or a door for closing, although these are not shown in Figure 8.

[0267] Figure 9 shows the melting furnace 800 of Figure 8 in a section along a plane defined by the lines A and B shown in Figure 8.

[0268] In the figures, recurring features are provided with the same reference numerals.

[0269] Figure 9 shows a section through the furnace chamber 811, the furnace chamber 811'', the furnace chamber 810, and the furnace chamber 811'. In the furnace chamber 811, the heating elements 861 in the form of heating rods arranged on the ceiling of the furnace chamber 811 can be seen. The pump 821 conveys molten metal through the furnace chambers in the direction indicated by the arrow 801'. The molten metal is pumped through an inlet opening 814 by the pump 821 into the second furnace chamber 811. In Figure 10, a section of Figures 8 and 9 is shown again enlarged to illustrate the furnace chamber 811'''. The furnace chamber 811''', ie the contaminant collection chamber, comprises a lowered area in the form of a floor depression 8112. A floor 8113 of an inflow area of ​​the furnace chamber 811''' is at the same level as a floor 8114 of the furnace chamber 811 in the outflow area of ​​the furnace chamber 811.Behind the inflow area of ​​the furnace chamber 811"', a depression 8112 is formed in the furnace chamber 811'". Sediments can pass from the furnace chamber 811 into the furnace chamber 811'" and are deposited in the depression 8112. A bottom 8115 of an outflow opening of the furnace chamber 811'" is arranged above a bottom of the depression 8112, so that the sediments cannot or only partially reach the downstream furnace chamber 810. The bottom of the furnace chamber 810 is at the same height as the bottom 8115 of the outflow opening of the furnace chamber 811'".

[0270] Figure 10 shows an optional maximum fill level kmax and an optional minimum fill level k minThe fill levels indicate a possible minimum and maximum fill level of molten metal that ensures proper operation of the furnace. If furnace chamber 811 is heated electrically and not with burners that produce exhaust gases, the opening for the melt to furnace chamber 811"' can end above the maximum fill level kmax of the melt in the furnace, since no exhaust gases escape. Thus, impurities on the melt surface can be conveyed from furnace chamber 811 to furnace chamber 811'" at any fill level. Due to the melt circulation, these impurities are continuously transported from the first chamber into furnace chamber 811'" during melting operation of the furnace; this also applies to the sediments in the first chamber. A weir in the outflow area of ​​furnace chamber 811"' retains the impurities on the melt surface, allowing them to be skimmed off.The sediments are retained by the floor depression 8112. An outlet valve (not shown) is located at the lowest point of the lowered area 8112. The conveying direction of the molten metal is again indicated in Figure 10 by the arrow 801'.

[0271] Figure 11 shows a section through the furnace chamber 811 in the vertical direction along the line C shown in Figure 8. The charging opening 840 is clearly visible. A charging opening door (not shown) for closing the charging opening is arranged at the charging opening 840. The cleaning opening 870 is closed by a cleaning opening door 870'. The arrows 801' schematically indicate the flow of the molten metal from the inlet opening 814 toward the outlet opening 813. An outer wall of the furnace chamber 811, on which the charging opening 840 is formed, can be formed as an inclined plane (also referred to as a cleaning slope) 8401 (as shown in Fig. 11).

[0272] Figure 12 shows an alternative embodiment of the furnace chamber 811 of the melting furnace 800 of Figures 8-11. A loading ramp 8402 may be formed at the loading opening 840 in addition to or as an alternative to the cleaning slope 8401. The loading ramp 8402 is arranged, in particular, above a molten metal filling level k. Metal parts can thus dry on the loading ramp 8402. One or more gas burners 862 may be arranged above the loading ramp 8402 for heating the metal arranged on the loading ramp 8402, as shown, for example, in Figure 13.

[0273] Additionally or alternatively, a gas circulation device 880 may be provided in the furnace chamber 811. This is shown in Fig. 14. The gas circulation device 880 may comprise a fan 881. This fan may be designed and arranged such that furnace atmosphere is removed from a first region of the furnace chamber 811 and blown back into the area of ​​the loading ramp 8402. In particular, air heated by the heating elements 861 can be blown back into the furnace interior in the area of ​​the loading ramp 8402, in particular above the loading ramp. The arrows 802' indicate a gas circulation direction of the gas circulation device 880. Figure 15 shows a section through the second furnace chamber of the melting furnace of Figures 8 to 14, wherein gas burners 861' are provided instead of electrical heating elements 861.

[0274] Figure 16 shows a schematic representation of a melting furnace 1500 for melting metal. Figure 16 shows a plan view of the melting furnace 1500 in a horizontal section through the melting furnace 1500.

[0275] The 1500 melting furnace is particularly suitable for melting metals with a melting point below 1200°C. The 1500 melting furnace is particularly suitable for melting lumpy feedstock (1550 melting stock), for example, the size of a car rim. Furthermore, the 1500 melting furnace is suitable for simultaneously accommodating and melting several larger metal parts.

[0276] The melting furnace comprises a first furnace chamber 1510 and a second furnace chamber 1511. The first furnace chamber 1510 and the second furnace chamber 1511 are formed by furnace walls 1512. A partition wall 1512' separates the first furnace chamber 1510 from the second furnace chamber 1511. The partition wall is arranged in this case such that it forms an interior region 15121. The first furnace chamber 1510 and the second furnace chamber 1511 are fluidly connected to one another via a first connecting opening 1513 and a second connecting opening 1514.

[0277] The melting furnace 1500 has a first loading opening 1540. The loading opening 1540 is configured to supply metal to be melted, in particular, a melting material 1550, in this case, for example, a car rim. The loading opening 1540 is arranged on the furnace chamber 1511 such that the melting material 1550 can be introduced from an environment 1 surrounding the melting furnace 1500 through the loading opening 1540 into the second furnace chamber 1511 when the loading opening 1540 is open. The loading opening 1540 has a width of 60 cm and a height of 60 cm. For example, a conveyor or a robot can be connected to the loading opening so that the loading material can be introduced into the melting furnace 1500 in an automated manner. The loading opening 1540 can be closed by a loading opening door 1541.A furnace interior, comprising the furnace chamber 1510, can be closed off from the environment 1 surrounding the melting furnace by the charging opening door 1541.

[0278] The loading opening 1540 and / or 1540' and / or 1540" for the loading parts can be arranged vertically or almost vertically. This means that an angle between the vertical and the plane of the loading opening can in particular be less than 45°, preferably less than 25° and / or equal to 0° or greater than 0°.

[0279] The charging opening 1540 and / or 1540' and / or 1540" can be arranged horizontally or almost horizontally, so that the charging parts are added to the melt from above. This means that an angle between the horizontal and the plane of the charging opening can in particular be less than 45°, preferably less than 25° and / or equal to 0° or greater than 0°. The cover of the charging opening can then be a lid that is pivoted upwards to expose the corresponding charging opening 1540 and / or 1540' and / or 1540". One or more of the charging openings can be arranged horizontally as described above and one or more charging openings can be arranged vertically as described above.

[0280] For feeding a collection of feed parts, which are, for example, pushed or tilted from a feed container into the melt, the width of the feed chamber can be greater than the width of the inlet or outlet opening of the corresponding furnace chamber. This is illustrated in Figure 16 as an example for the feed chamber 1511 at the feed opening 1540'.

[0281] The melting furnace 1500 has a second charging opening 1540'. The charging opening 1540' is configured to supply metal to be melted, in particular, melting material 1550', in this case, for example, a plurality of metal ingots. The charging opening 1540' is arranged on the furnace chamber 1511 such that the melting material 1550' can be introduced from an environment 1 surrounding the melting furnace 1500 through the charging opening 1540' into the second furnace chamber 1511 when the charging opening 1540' is open. The charging opening 1540' has a width of 150 cm and a height of 120 cm. This has the advantage that larger quantities of charging material can be introduced into the second furnace chamber simultaneously. For example, the feed material can be tipped from a collecting container through the feed opening 540'. The melt material 1550' can, for example, be in the form of returns from a casting process.The melting furnace 1500 can have receiving devices for such a collecting container on an outer wall. For example, a conveyor or a robot can be connected to the loading opening so that loading material can be automatically introduced into the melting furnace 1500. The loading opening 1540' can be closed by a loading opening door 1541'. A furnace interior, comprising the furnace chamber 1510 and the second furnace chamber 1511, can be closed from the environment 1 surrounding the melting furnace 1500 by the loading opening door 1541'.

[0282] The melting furnace 1500 has a third charging opening 1540". The charging opening 1540" is designed to supply metal to be melted, in particular melting material 1550", in this case, for example, metal chips. The charging opening 1540" is arranged on the furnace chamber 1511 in such a way that the melting material 1550" is fed from a melting furnace

[0283] 1500 surrounding environment 1 through the charging opening 1540" into the second furnace chamber 1511 when the charging opening 1540" is open. The melting material 1550" can be in the form of metal chips, for example. The charging opening 1540" can be closed by a charging opening door 1541". A furnace interior, comprising the furnace chamber 1510 and the second furnace chamber 1511, can optionally be closed by the charging opening door 1541" from the environment 1 surrounding the melting furnace 1500. It should be noted, however, that a charging opening door is not mandatory, particularly due to the regions a with reduced flow cross-section in front of and behind the charging opening 1540".

[0284] In particular, regions of the melting furnace 1500 that are designed to come into contact with molten metal are refractorily lined. For example, the furnace chamber 1510 and the furnace chamber 1511 are refractorily lined, at least in some regions. The refractorily lined regions are designed to withstand temperatures of at least -50°C and / or at least -20°C and / or at least 0°C. The refractorily lined regions are designed to withstand temperatures of up to 5000°C and / or up to 2000°C and / or up to 1500°C. For this purpose, a molten metal present in the melting furnace 500, in particular in the furnace chambers 1510 and 1511,

[0285] 1501 heated to temperatures of at least 500 °C and / or at least 700 °C and / or at least 900 °C and / or at least 1100 °C.

[0286] In the dark marked areas a, a flow cross-section is reduced, whereby these areas are located upstream of the feed openings.

[0287] The melting furnace 1500 is electrically heated. The melting furnace 1500 comprises a first heating device 1530 with electrically heatable immersion heating elements 1531 arranged in the furnace chamber 1510. Preferably, six immersion heating elements 1531 are arranged in the furnace chamber 1510. The immersion heating elements 1531 are electrically driven to generate heat.

[0288] The 1531 immersion heating elements have a fire-resistant surface and can be immersed in molten metal to heat it.

[0289] Furnace chambers 1510 and 1511 are at least partially filled with molten metal 1501, for example, molten aluminum. The molten aluminum comprises aluminum. The molten aluminum can be, for example, an aluminum alloy. About 80% of the molten metal 1501 located in the melting furnace 1500 is located in the furnace chamber 1511. About 20% of the molten metal 201 located in the melting furnace 1500 is located in the furnace chamber 1510. The molten metal 1501 has a temperature of about 750°C.

[0290] The melting furnace 1500 comprises a first circulation device 1520, which is configured to generate a molten metal flow, at least partially represented by the arrows 1501', within the melting furnace 1500. The circulation device 1520 comprises a pump 1521 for conveying the molten metal 1501. The melting furnace 1500 comprises a second circulation device 1520', which is configured to generate a molten metal flow, at least partially represented by the arrows 1501', within the melting furnace 1500. The circulation device 1520' comprises a pump 1521' for conveying the molten metal 1501.

[0291] The circulation device 1520 is arranged and configured such that the molten metal flow 1501' circulates between the immersion heating elements 1531 and the pump 1521. The pump 1521 is arranged in the first furnace chamber 1510. A discharge port of the pump 1521 is sealingly connected to the second connection opening 1514 such that molten metal 1501 flowing through the second connection opening 1514 first flows through the pump 1521. An intake port of the pump 1521 is arranged facing the immersion heating elements 1531. The second connection opening 1513 is arranged upstream of the immersion heating elements 1531, so that the molten metal 1501, which is conveyed by the pump 1521, flows through the first furnace chamber 1510, flows around the immersion heating elements 1531, flows into the pump 1521, and then flows through the second connection opening 1514 into the second furnace chamber 1511. Thus, it can be seen that the molten metal circulates within the melting furnace 100.The flow path runs through a type of annular channel, which in particular encompasses all of the described furnace chambers. As the liquid flows around the immersion heating elements 1531, the molten metal 1501 is heated. In particular, the immersion heating elements 1531 can be arranged in a row in the direction of flow. Alternatively, one or more further rows or just one or two rows of immersion heating elements 1531 can be provided. The immersion heating elements 1531 of a first row can be arranged offset from the immersion heating elements 1531 of a second row. The immersion heating elements 1531 of a first row can alternatively be arranged one behind the other or in alignment with the immersion heating elements 1531 of a second row. Some immersion heating elements 1531 can also be aligned with one another downstream, and some further immersion heating elements 1531 can be arranged offset from one another downstream.The second circulation device 1520', in particular the second pump 1521', is arranged downstream of the first circulation device. The second pump 1521' is arranged in particular between the feed opening 1540" and the feed opening 1540'.

[0292] The first circulation device 1520' increases the pressure of the melt, for example, to compensate for the pressure loss of specially shaped flow channels or flow elements, which are necessary, for example, for the immersion melting of metal chips. The second circulation device 1520' is optional. The melting furnace 1500 can also be designed without the second circulation device. The melting furnace can include special flow channels to increase or decrease the pressure of the melt.

[0293] Preferably, a contaminant collection chamber 1511' is arranged downstream of one or more or all of the charging openings 1540 and / or 1540' and / or 1540". The contaminant collection chamber may be configured in accordance with the furnace chamber 811'" described with respect to the melting furnace 800. The contaminant collection chamber may have a closable opening for removing contaminants.

[0294] When melting material 1550 has been introduced into the furnace chamber 1511 via the charging opening 1540", melting material 1550 is located in the furnace chamber 1511. When the pump 1521 is switched on, the molten metal 1501 flows around the melting material 1550 located in the furnace chamber 1511 and heats it so that it melts. The molten metal 1501 flows from the pressure port of the pump 1521 from the connection opening 1514 through the second furnace chamber 1511, first flowing around the melt 1550" and then the melt 1550' and then the melt 1550 and flows through the connection opening 1513, flows around the immersion heating elements 1531 in the first furnace chamber 1510 and flows to the intake port of the pump 1521. Between the charging opening 1540" and 1540', the pump 1521' can be arranged such that a pressure port points to the charging opening 1540' and a intake port points to the charging opening 1540'.

[0295] Alternatively or in addition to a pump 1521, the circulation device 1520 can comprise a stirrer for circulating the molten metal 1501. The stirrer can be arranged, for example, outside the furnace chambers and can be electromagnetic. The stirrer can be arranged, for example, below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 1501 can be set into a rotational motion.

[0296] The embodiment of Figure 16 can additionally have a second heating device (not shown). In particular, the second heating device can be arranged in the region of the second furnace chamber 1511. The second heating device can in particular be an electric heating device. In particular, the second heating device can be arranged in a region that does not come into contact with the melt. In particular, the second heating device can be arranged above the melt. The second heating device can comprise second heating elements in the form of heating rods. Additionally or alternatively, the second heating device can comprise heating elements in the form of gas burners. The heating elements can be arranged under a ceiling of a furnace chamber, in particular of one or both of the furnace chambers 1510, 1511. The heating rods are in particular electrically operated.When switched on, the heating elements can radiate heat, so that the melt below the second heating elements is heated.

[0297] It should be noted that features disclosed with respect to one of the embodiments may be combined with another embodiment, even if this has not been explicitly described in the description of the corresponding embodiment.

[0298] Figure 17 shows a sectional view of a melting furnace 1700 for melting metal according to another embodiment. The sectional plane runs horizontally in space and, for example, approximately halfway along the vertical height of the melting furnace 1700. The melting furnace 1700 has a furnace housing 1703 surrounding an annular melt channel (annular channel) 1710. More specifically, the melting furnace 1700 has refractory walls 1701 located in the furnace housing 1703. The refractory side walls 1701 and the illustrated floor form the annular melt channel 1710, which is enclosed (i.e., surrounded) by the furnace housing 1703.

[0299] The annular channel 1710 is rectangular in shape, for example. A molten metal flow circulates within the annular channel 1710. Exemplary flow arrows 1702 indicate a flow direction, which can also be reversed. The flow arrows 1702 also indicate an opening in an intermediate wall in the annular channel 1710 located outside the cutting plane, by means of which the annular channel 1710 assumes a continuous or closed annular shape.

[0300] The annular channel 1710 (and the furnace housing 1703) encircles an interior area 1752 of the melting furnace 1700. This interior area 1752 is preferably free of furnace components, with the exception of any components permanently attached to the furnace housing 1701. The interior area 1752 is generally accessible for maintenance work and sufficiently large to allow maintenance personnel to be present there.

[0301] The annular channel 1710 comprises a circulation device 1720, preferably in the form of a pump. This pump conveys a molten metal, for example, clockwise or counterclockwise through the annular channel 1710.

[0302] The annular channel 1710 further comprises heating devices 1730, each having, for example, five immersion heating elements 1731. All of the immersion heating elements 1731 are offset transversely to a flow direction (see arrow 1702) and are thus positioned outside the flow shadow of the respective other immersion heating elements 1731.

[0303] The annular channel 1710 also includes a feed opening (not shown separately) which is positioned directly above a feed material melting area 1750.

[0304] The annular channel 1710 has a plurality of rectilinear regions 1712, each of which is angled to adjacent rectilinear regions 1712, for example, by approximately 90° here. The rectilinear regions 1712 are connected to one another via deflection regions 1714. An inner wall 1711 of the annular channel 1710 is rounded or chamfered in the region of the deflection regions 1714, as explained in more detail below.

[0305] A bottom weir 1740 is positioned in or adjacent to at least some of the deflection regions 1714. This defines a height step within the annular channel 1710 and, in particular, an elevation of the channel floor in or adjacent to the deflection regions 1714. This reduces a free wall area on the inner wall 1711 in the region of the deflection regions 1714 against which the molten metal can adhere. In other words, the annular channel 1710 is divided into straight sections up to the height of the bottom weirs 1740. This reduces stress peaks that could occur more frequently in non-straight wall regions of the annular channel 1710 as a result of potentially solidifying molten metal.

[0306] To enable complete flow of the melt out of the annular channel 1710, the bottom weirs 1740 each have connecting channels 1742 extending along the flow direction. These are designed as incisions down to a channel bottom within the, for example, block-like bottom weirs 1740. Contraction of the solidifying melt can also lead to increased stresses at these connecting channels 1742, but any damage is less relevant at the bottom weirs 1740 than at the deflection region 1714 (and more precisely, than at the corners of the inner walls within the deflection regions 1714). Furthermore, the stresses at the bottom weirs 1740 can be reduced by plastic deformation of the metal because the amount of metal in the connecting channels 1742 is smaller than at the aforementioned corners.

[0307] In Figure 17, the corners 1715 of some of the deflection regions 1714 are marked, with these corners 1715 being chamfered to further reduce stress peaks during solidification of molten metal. For example, only the inner corners 1715 of the inner wall 1711 and / or near the inner region 1752 are chamfered accordingly, since higher stresses occur there. A further advantage of the chamfered inner corners 1715 is a reduction in dead zones in the flow direction behind the corners 1715 and a reduction in flow separation in the region of the corners 1715.

[0308] Figure 18 shows a subdivision of the melting furnace 1700 from Fig. 17 into individual modules, numbered 1-12. The modules 1-12 are arranged in a row along a flow direction through the annular channel 1710. Each module 1-12 is connected to a module 1-12 preceding and following in the flow direction in a melt-conducting and fluid-tight manner with respect to the molten metal. Depending on the desired furnace configuration, the modules 1-12 can be flexibly selected, arranged, and connected to one another. The following modules are provided: Number 1: Module with circulation pump; Number 2: Module with vertical charging opening, i.e.which in particular enables metal to be fed along an at least approximately horizontal axis, since the feed opening itself lies in a vertical spatial plane; Number 3: Module with an opening for skimming off the melt surface (comparable to or comprising a contaminant collection chamber disclosed here); Numbers 4, 5, 6, 8, 9, 10: Modules with immersion heating elements; Number 7: Module with a horizontal feed opening, ie which in particular enables metal to be fed along an at least approximately vertical axis, since the feed opening itself lies in a horizontal spatial plane; Number 11: Corner module; Number 12: Module for metal melt removal.

[0309] Fig. 19 shows an alternative configuration of a melting furnace 100 according to a further embodiment, wherein the melting furnace 100 is composed of exactly two modules 1-2. The modules 1, 2 each have a rectangular shape that is open on one side, e.g., based on their outer outline in the plan view shown. On one of their long sides and in particular at both ends thereof, each module 1, 2 has connecting regions 2000 for fluid-tight and mechanical connection with the other module 1, 2. The connecting regions 2000 each comprise an opening through which melt can be exchanged with the corresponding other module 1, 2. Depending on the flow direction, this opening functions as an inflow or outflow opening. The connecting regions 2000 also each comprise flange regions 2010, which serve as interfaces for connecting the connecting regions 2000 to one another. The flange regions 2010 can, for example,a furnace housing encompassed by the modules 1, 2 each runs in a ring-like manner near the connecting areas 2000.

[0310] It can again be seen that modules 1, 2 define an annular channel 2012 that encircles a free interior area 2014. Furthermore, one of modules 1 comprises a circulation device 2016, and, for example, both modules 1, 2 comprise immersion heating elements 2018. A position of a metal feed via a charging opening (not shown separately) is indicated by an arrow 2020. A position of a melt removal via a tap opening (not shown separately), melt removal pump, or other device is indicated by an arrow 2022.

[0311] By dividing the melting furnace into two modules 1, 2, transport to the installation site can be made easier. In particular, a width dimension of the individual modules 1, 2, which runs vertically in the plan view from Fig. 19, can be significantly reduced compared to the melting furnace assembled from them. Fig. 20 shows an alternative configuration of a melting furnace 100 according to a further exemplary embodiment, wherein the melting furnace 100 is composed of exactly four modules 1-4. Two of the modules 1, 2 are designed similarly to the variant from Fig. 19, but are not directly connected to one another. Instead, they are indirectly connected to one another via further modules 3, 4, wherein each of the further modules 3, 4 defines a section of a vertically running transverse side of the melting furnace in the plan view from Fig. 20.By way of example only, these additional modules 3, 4 define comparatively shorter sections of the annular channel 2012 and both of the additional modules 3, 4 have immersion heating elements 2018. The additional modules 3, 4 also each have connection areas 2000 and flange areas 2010 of the type explained above.

[0312] The additional modules 3 and 4 allow the volume of the annular channel 2012 and thus the capacity of the melting furnace to be increased. This particularly applies to the melting capacity due to the additional immersion heating elements 2018 of the additional modules 3 and 4.

[0313] Figure 21 shows a view of an individual module 1780 of the melting furnace 1700 from Figures 17 & 18, wherein the individual module 1780 includes a lid lifting device 1790. First, it can be seen that the individual module 1780, like each of the modules 1-12 from Figure 18, includes an inflow opening 1792 and an outflow opening 1794 facing away from the viewer. Depending on the flow direction, the functional assignment of the inflow and outflow can alternate between the openings 1792, 1794. Example flow arrows 1702 through the individual module 1780 are shown in Figure 21.

[0314] The individual module 1780 comprises a cover 1796. The immersion heating element 1731 is attached to this cover, for example, so that the individual module 1780 corresponds, for example, to module 4 from Fig. 18. The cover 1796 can be lifted vertically, for example, by electric motor or hydraulically, using the cover lifting device 1790. The cover lifting device 1790 faces the interior region 1752 from Fig. 17 and is accessible from there for maintenance purposes. The immersion heating element 1731, raised together with the cover 1796, can, however, be accessible from an outside of the melting furnace 1700. The immersion heating element 1731 is therefore easier to access than the cover lifting device 1790, which takes into account its shorter maintenance intervals.

[0315] By arranging the lid lifting device 1790 on one side of the individual module 1780 (here: inside), work from the corresponding other side (here: outside) on the melt surface (e.g., for the purpose of removing impurities) and / or on the immersion heating elements 1731 is not hindered by the lid lifting device 1790.

[0316] 1 Surroundings of the melting furnace

[0317] 100 melting furnace

[0318] 101 Metal melting

[0319] 101' molten metal flow

[0320] 110 Furnace chamber

[0321] 111 second furnace chamber

[0322] 120 Circulation device

[0323] 121 Pump

[0324] 130 first heating device

[0325] 131 Immersion heating element

[0326] 140 first loading opening

[0327] 141 Loading opening door

[0328] 200 melting furnace

[0329] 201 Metal melt

[0330] 201' molten metal flow

[0331] 210 Furnace chamber

[0332] 211 second furnace chamber

[0333] 212 furnace wall

[0334] 212' partition wall

[0335] 213 first connection opening 214 second connection opening

[0336] 220 Circulation device

[0337] 221 Pump

[0338] 230 first heating device

[0339] 231 Immersion heating element

[0340] 240 first loading opening

[0341] 241 Loading opening door

[0342] 250 melting material

[0343] 300 melting furnace

[0344] 301 molten metal

[0345] 301' molten metal flow

[0346] 310 Furnace chamber

[0347] 311 second furnace chamber

[0348] 312 furnace wall

[0349] 312' partition wall

[0350] 313 first connection opening

[0351] 314 second connecting opening

[0352] 320 Circulation device

[0353] 321 Pump

[0354] 330 first heating device

[0355] 331 immersion heating element

[0356] 340 first loading opening 341 loading opening door

[0357] 350 melt

[0358] 400 melting furnace

[0359] 401 Metal melt

[0360] 401' molten metal flow

[0361] 410 Furnace chamber

[0362] 411 second furnace chamber

[0363] 412 furnace wall

[0364] 412' partition wall

[0365] 413 first connection opening

[0366] 414 second connection opening

[0367] 420 Circulation device

[0368] 421 Pump

[0369] 430 first heating device

[0370] 431 immersion heating element

[0371] 440 first loading opening

[0372] 440' second loading opening

[0373] 441 first loading opening door

[0374] 441' second loading opening door

[0375] 450 melting material (metal chips)

[0376] 450' melting material (car rim) 500 melting furnace

[0377] 501 Metal melt

[0378] 501' molten metal flow

[0379] 510 Furnace chamber

[0380] 511 second furnace chamber

[0381] 512 furnace wall

[0382] 512' partition wall

[0383] 513 first connection opening

[0384] 514 second connection opening

[0385] 520 Circulation device

[0386] 521 Pump

[0387] 530 first heating device

[0388] 531 immersion heating element

[0389] 540 first loading opening

[0390] 540' second loading opening

[0391] 541 first loading opening door

[0392] 541' second loading opening door

[0393] 550 melt (car rim)

[0394] 550' melting material (metal to be melted, e.g. metal ingots)

[0395] 600 melting furnace

[0396] 601 Metal melt

[0397] 601' Metal melt flow 610 Furnace chamber

[0398] 611 second furnace chamber

[0399] 612 furnace wall

[0400] 612' partition wall

[0401] 613 first connection opening

[0402] 614 second connecting opening

[0403] 620 Circulation device

[0404] 621 Pump

[0405] 630 first heating device

[0406] 631 immersion heating element

[0407] 640 first loading opening

[0408] 641 Loading opening door

[0409] 650 melt

[0410] 660 second heating device

[0411] 661 second heating elements

[0412] 700 melting furnace

[0413] 701 Metal melt

[0414] 701' molten metal flow

[0415] 710 Furnace chamber

[0416] 711 second furnace chamber

[0417] 712 furnace wall

[0418] 712' Partition wall 713 first connecting opening

[0419] 714 second connecting opening

[0420] 720 Circulation device

[0421] 721 Pump

[0422] 730 first heating device

[0423] 731 immersion heating element

[0424] 740 first loading opening

[0425] 740' second loading opening

[0426] 741 first loading opening door

[0427] 741' second loading opening door

[0428] 750 melt (car rim)

[0429] 750' melting material (metal to be melted, e.g. metal ingots)

[0430] 760 second heating device

[0431] 761 second heating elements

[0432] 800 melting furnace

[0433] 810 Furnace chamber

[0434] 811 second furnace chamber

[0435] 811' additional furnace chamber

[0436] 811" additional furnace chamber

[0437] 811"' additional furnace chamber

[0438] 811' v Removal bag

[0439] 8112 Recess 8113 Floor inlet area of ​​the furnace chamber 811'"

[0440] 8114 Floor outlet area of ​​the furnace chamber 811

[0441] 8115 Bottom of the outlet opening of the furnace chamber 811"'

[0442] 813 Outlet opening

[0443] 814 Inlet opening

[0444] 820 Circulation device

[0445] 821 Pump

[0446] 830 first heating device

[0447] 831 immersion heating element

[0448] 840 first loading opening

[0449] 8401 Ramp

[0450] 8402 loading ramp

[0451] 840' second loading opening

[0452] 860 second heating device

[0453] 861 second heating elements

[0454] 861' gas burner

[0455] 862 gas burners

[0456] 870 cleaning opening

[0457] 870' cleaning opening door

[0458] 880 Gas circulation device

[0459] 881 Blower kmax Maximum filling level kmin Minimum filling level 1500 Melting furnace

[0460] 1501 metal melt

[0461] 1501' molten metal flow

[0462] 1510 furnace chamber

[0463] 1511 second furnace chamber

[0464] 1511' Contaminant collection chamber

[0465] 1512 furnace wall

[0466] 1512' partition wall

[0467] 15121 Interior

[0468] 1513 first connection opening

[0469] 1514 second connecting opening

[0470] 1520 Circulation device

[0471] 1521 Pump

[0472] 1520' second circulation device

[0473] 1521' second pump

[0474] 1530 first heating device

[0475] 1531 immersion heating element

[0476] 1540 first loading opening

[0477] 1540' second loading opening

[0478] 1540" third loading opening

[0479] 1541 first loading opening door

[0480] 1541' second loading opening door 1541" third loading opening door

[0481] 1550 melt (car rim)

[0482] 1550' melting material (metal to be melted, e.g. metal ingots)

[0483] 1550" Melt material (metal to be melted, e.g. metal chips) a areas of reduced flow cross-section

[0484] 1700 melting furnace

[0485] 1701 Refractory lined side wall of the furnace

[0486] 1703 furnace housing

[0487] 1702 Flow arrow / flow direction

[0488] 1710 Ring Canal

[0489] 1711 interior wall

[0490] 1712 straight section

[0491] 1714 Deflection area

[0492] 1715 Corner with bevel

[0493] 1720 circulation device

[0494] 1730 heating device

[0495] 1731 immersion heating element

[0496] 1740 Bodenwehr

[0497] 1742 connecting canal

[0498] 1750 Feed material melting area

[0499] 1752 interior

[0500] 1754 canal segment

[0501] 1780 Single module 1790 Lid lifting device

[0502] 1792 inlet opening

[0503] 1794 outlet opening

[0504] 1796 cover 2000 connection area

[0505] 2010 flange area

[0506] 2012 Ring Canal

[0507] 2014 Interior

[0508] 2016 Circulation device 2018 Immersion heating elements

[0509] 2020 Metal Feed

[0510] 2022 Melt withdrawal

[0511] 1-12 Module

Claims

1. Melting furnace (100) for melting metal, with: - at least one feed opening (140) for supplying metal to be melted; - a first heating device (130) with at least one electrically heated immersion heating element (131); and - a circulation device (120) which is set up to generate a molten metal flow within the melting furnace (100) which circulates between the circulation device (120) and the immersion heating element (131) and flows past the charging opening (140).

2. Melting furnace (100) according to claim 1, comprising an annular channel (1710) which is an annular melting channel, wherein the heating device (130) and the circulation device (120) are arranged in the annular channel (1710) and / or wherein the annular channel (1710) is accessible through the charging opening (140).

3. Melting furnace (100) according to claim 2, wherein the metal molten flow passes circulatingly through the annular channel (1710), in particular as an open trough flow.

4. Melting furnace (100) according to one of the preceding claims, wherein the melting furnace (100) has an accessible and / or unobstructed interior area (1752) which is surrounded by the annular channel (1710).

5. Melting furnace (100) according to one of the preceding claims, wherein the annular channel (1710) has a plurality of modules (1-12) through which the molten metal flow passes.

6. Melting furnace (100) according to claim 5, wherein each module (1-12) has at least one inlet opening (1792) and at least one outlet opening (1794).

7. Melting furnace (100) according to claim 5 or 6, wherein each module (1-12) is connected to at least two further modules (1-12) in a fluid-tight manner for the transfer of the molten metal flow between the modules (1-12).

8. Melting furnace (100) according to one of claims 5 to 7, wherein each module (1-12) comprises a furnace housing lined with refractory material.

9. Melting furnace (100) according to one of claims 5 to 8, wherein the following applies to the dimensions of at least a plurality of the modules (1-12): - a height is less than or equal to 2.9 m or the height is less than or equal to 3.8 m; and / or - at least one first horizontal dimension is less than or equal to 2.5 m or is less than or equal to 3 m; and / or - at least one second horizontal dimension is less than or equal to 6 m or is less than or equal to 13.6 m.

10. Melting furnace (100) according to claim 6, wherein the modules (1-12) have a connection area at at least one inlet opening (1792) and / or at the at least one outlet opening (1794) by means of which they can be connected to any other module (1-12).

11. Melting furnace (100) according to one of the preceding claims, wherein the circulation device (120) comprises a mechanical or an electromagnetic pump (121) and the molten metal flow flows from a pressure side to a suction side of the pump (121) as part of its circulation.

12. Melting furnace (100) according to one of the preceding claims, wherein the heating device (130) is arranged in a section of the annular channel (1710) in which a substantially complete volume- The exchange of the molten metal occurs as a result of the molten metal flow.

13. Melting furnace (100) according to one of the preceding claims, wherein the heating device (130) comprises a plurality of immersion heating elements (131), wherein each immersion heating element (131) is arranged at least partially outside of a flow shadow of at least one correspondingly different immersion heating element (131).

14. Melting furnace (100) according to one of the preceding claims, characterized in that the charging opening is positioned vertically above the metal molten flow and the metal molten flow can be generated in such a way that it flows towards a charge material (250 or / and 350 or / and 450 or / and 550) supplied to the melting furnace (100) through the charging opening at a flow velocity.

15. Melting furnace (100) according to claim 14, characterized in that the molten metal flow passes over at least a part of the supplied feed material at a flow velocity which corresponds at least to an average flow velocity, in particular at least twice the average flow velocity, of the molten metal flow during its circulation in the melting furnace (100).

16. Melting furnace (100) according to one of the preceding claims, further comprising at least a second heating device (660) which is positioned or positionable outside the molten metal (101) and which is configured to supply heat to the molten metal (101) and / or to a metal to be melted.

17. Melting furnace (100) according to claim 16, wherein the second heating device (660) is electrically heated and in particular is designed as a ceiling radiant heater and / or wherein the second heating device has at least one gas burner (861').

18. Melting furnace (100) according to claim 16 or 17, wherein the second heating device (660) is arranged vertically higher than the immersion heating element (131, 631) and / or wherein the second heating device (660) is at least at the same vertical height or higher than a charging opening of a furnace chamber (611) with the second Heating device (640) is arranged.

19. Melting furnace (100) according to one of claims 16 to 18, wherein the second heating device (660) and the first heating device (130, 630) are arranged in different furnace chambers (610, 611, 612, 612').

20. Melting furnace (100) according to claim 19, wherein the furnace chamber (611) in which the second heating device (660) is arranged has a charging opening (640) for supplying metal to be melted.

21. Melting furnace (100) according to claim 20, wherein an inlet area (614) of the furnace chamber (611) in which the second heating device (660) is arranged is located closer to the charging opening (640) than an outlet area of ​​this furnace chamber (613).

22. Melting furnace (100) according to claim 20 or 21, wherein the furnace chamber (610) in which the first heating device (630 or 130) is arranged comprises a smaller dimensioned charging opening (140) than the charging opening (640) of the furnace chamber (611) in which the second heating device (660) is arranged.

23. Melting furnace (100) according to one of claims 19 to 22, wherein the circulating device (120) is positioned near an inlet area (614) of the furnace chamber (611) in which the second heating device (660) is arranged, and / or opens into this inlet area, in particular wherein the circulating device (120) is positioned outside the furnace chamber (611) which has the second heating device (660).

24. Melting furnace (100) according to one of claims 16 to 23, wherein the metal molten flow can be generated such that it flows from the first heating device (130 or 630) in the direction of the circulation device (120) and from the circulation device (120) in the direction of the second heating device (660).

25. Melting furnace (100) according to one of the preceding claims, wherein the melting furnace (100) has at least one impurity collection chamber (811'') through which the molten metal flow can pass. exhibits, within which impurities contained in the metal melt (101) can be collected.

26. Melting furnace (100) according to claim 25, wherein the impurity collection chamber (811'") has an inlet area and an outlet area and a bottom area (8112) that is lowered at least relative to the outlet area for collecting impurities that settle there, and / or wherein the inlet area has an opening cross-section that extends to a bottom area (8112) of a furnace chamber (811) that is arranged upstream of the impurity collection chamber (811'').

27. Melting furnace (100) according to one of claims 24 or 25, wherein the impurity collection chamber (811'') comprises an outlet valve which can be opened to allow impurities that have settled in the bottom area (8112) to drain away.

28. Melting furnace (100) according to claim 24, wherein the impurity collection chamber (811'') has an outflow area with an opening cross-section, wherein an upper edge of the opening cross-section is lower than a minimum permissible level (k-min) of the molten metal in a furnace chamber located upstream relative to the impurity collection chamber (811'"), and wherein the inflow area has an opening cross-section whose upper edge is higher than a maximum permissible level (k-max) of the molten metal in the upstream furnace chamber.

29. Melting furnace (100) according to one of claims 24 to 28, wherein the inlet area of ​​the impurity collection chamber (811') is closer to a charging opening (140 and / or 240 and / or 340 and / or 440 and / or 540 and / or 540' and or 640 and / or 740 and / or 740') than the outlet area of ​​the impurity collection chamber (811').

30. Melting furnace (100) with a first impurity collection chamber (811'") according to one of claims 16 to 17 and with a second impurity collection chamber (811'") according to claim 18, wherein the first and second impurity collection chambers (811'") can be successively through which the molten metal flow can pass.

31. Melting furnace (100) according to one of the preceding claims, further comprising a charging area (8402) which is positioned or positionable outside the molten metal (101) and is equipped to receive metal to be melted.

32. Melting furnace (100) according to claim 31, wherein the charging area (8402) is inclined.

33. Melting furnace (100) according to claim 31, wherein the melting furnace (100) is configured to heat metal received in the charging area (8402), in particular by supplying heated air (881) from another area of ​​the melting furnace (100) or by means of a gas burner (862) directed towards the charging area.

34. Melting furnace (100) according to one of the preceding claims, further comprising a region (a) with at least a section-wise reduction of the flow cross-section, which is located upstream of the charging opening (840).

35. Melting furnace (100) according to one of the preceding claims, with a side furnace pocket for filling the melting furnace (100) with liquid metal.

36. Melting furnace (100) according to one of the preceding claims, comprising a control unit and a sensor configured to measure a level of the melt in the melting furnace and / or to detect melt at a certain vertical height in a chamber of the melting furnace, and to transmit a corresponding signal to the control unit.

37. Melting furnace (100) according to one of the preceding claims with claim 2, with at least one bottom weir (1740) at a bottom of the ring channel (1710), wherein the bottom weir (1740) defines a height difference between areas of the ring channel (1710) adjoining the bottom weir (1740) on both sides, wherein the areas of the ring channel (1710) adjoining the bottom weir (1740) on both sides run at an angle of more than 45° to each other, in particular of approximately 90°.

38. Melting furnace (100) according to claim 37, wherein the bottom weir (1740) has a connecting channel (1742), which is located at the same level as the floor of the adjacent areas of the annular channel (1710) and connects these areas to each other in a molten-conducting manner. Melting furnace (100) according to one of the preceding claims, further comprising a lid (1796) and a lid lifting device (1790) which is configured to lift the lid (1796) to make the annular channel (1710) accessible, in particular wherein the lid (1796) can be lifted essentially vertically and / or linearly, and wherein the lid lifting device (1790) is arranged on a side of the melting furnace (100) facing the interior area (1752).Melting furnace (100) according to one of the preceding claims, wherein the annular channel (1710) has at least one deflection region (1796) in which the flow direction of the molten metal flow is deflected by at least 45°, wherein side wall sections of the annular channel (1710) arranged upstream and downstream of the deflection region (1714) in the flow direction are rounded or transition into one another by means of a chamfer. Melting furnace (100) for melting metal, comprising: - at least one feed opening (140) for supplying metal to be melted; - a molten metal (101) taken up in the melting furnace (100); - a first heating device (130) with at least one electrically heated immersion heating element (131); - a circulation device (120) configured to generate a flow of molten metal around the immersion heating element (131), wherein the molten metal flow circulates between the circulation device (120) and the heating device (130) and flows past the charging opening (140). A method for melting metal using a melting furnace (100) according to one of the preceding claims, wherein the method comprises: - Generating the molten metal flow by means of the circulation device (120), so that the molten metal flow surrounds the immersion heating element (131) and circulates between the circulation device (120) and the heating device (130) and flows past the charging opening (140). Method for manufacturing a melting furnace (100) with an annular channel (1710) in which a molten metal can be circulated, comprising: - Connecting individual modules (1-12) to form at least one section of the melting furnace (100), wherein each module (1-12) comprises a channel segment of the annular channel (1710) as well as an inlet opening (1792) and at least one outlet opening (1794).

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