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 primary heating device (130) with at least one immersion type heating element (131) which can be heated electrically; and - a circulation device (120) configured to create a flow of molten metal inside the melting furnace (100). In addition, a method for melting metal with such a melting furnace (100) is described.

Description

[0001] The invention relates to a melting furnace and a method for melting metal using at least one electrically heated immersion heating element.

[0002] Melting furnaces for producing molten metal from solid metal material are well-known and widely used. An example can be found in DE 103 25 153 A1. Although these melting furnaces are already in widespread use, there is potential for improvement regarding operating costs and the associated economic efficiency in the production of molten metal.

[0003] US Patent 4,128,415 A discloses a system for melting metal scrap in a liquid molten medium, comprising a housing with a largely cylindrical cross-section and upper and lower sections. Metal scrap is introduced into a molten medium contained in the upper section of the housing. A supply of liquid molten medium is directed to the upper section by a spiral located in the lower section of the housing. The molten medium is supplied by the movement of an impeller located in the lower section and attached to a drive shaft. Blades are attached to the drive shaft that control the flow of the liquid molten medium and the metal scrap in the upper section of the housing by creating a vortex to mix the molten medium and the metal scrap.

[0004] WO 2021 / 095731 A1 teaches a metal melting device with which pure, low-oxide molten metal can be obtained, even when scrap material and new material are mixed or fed in independently. The problem mentioned is solved by a metal melting device comprising a melting chamber into which a liquid raw material is fed, and an air jet device that introduces air into the molten metal in the melting chamber, generating an eddy current within the molten metal inside the melting chamber.

[0005] DE 10 2016 200697 A1 discloses a melting furnace, in particular a glass melting furnace or a metal melting furnace, with a tank and a lid, wherein the melting furnace is realized as a component of refractory blocks, comprising the tank made of a refractory material, which is formed as a first refractory block with a melting chamber for melt, in particular a glass melt or a metal melt, and the lid made of a refractory material, which is formed as a second refractory block with a closure body for the melting chamber of the tank, wherein the refractory material is formed as a lightweight refractory brick and surfaces of the first and / or second refractory block coming into contact with the melt are finished with refractory mortar, in particular coated, and wherein a feed for the melt and / or a gas and / or atmosphere feed is integrated in the first refractory block, namely the refractory block of the tank, and a heating element in the second refractory block.namely, the refractory block of the lid, which is integrated.

[0006] The present application therefore aims to improve the efficiency and, in particular, the cost-effectiveness of producing molten metals using melting furnaces.

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

[0008] Accordingly, a melting furnace for melting metal is disclosed, including: a first heating device with at least one electrically heated immersion heating element; and a circulation device designed to generate a flow of molten metal within the melting furnace.

[0009] The invention recognizes that the economic efficiency of existing melting furnaces is particularly influenced by the energy source used and its cost. To date, gas has been predominantly used as the energy source for melting metals. The invention departs from this by providing, at least partially, electrical energy as the energy source. Depending on the source of the electrical energy, potentially lower costs can be achieved compared to operation with gas as the energy source.

[0010] Furthermore, the invention 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.

[0011] The use of the circulation device can further accelerate the melting process. For example, this allows the flow of hot molten metal around the supplied solid metal, thus accelerating the melting of the still-solid metal. Additionally or alternatively, the flow can also extend to at least one immersion heating element, as explained in more detail below. This improves the heat transfer from the immersion heating element to or into the molten metal.

[0012] The first heating device can include 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 include at least one power connection and / or at least one connecting line to obtain electrical energy. The immersion heating element can be configured to convert the electrical energy into heat energy, for example, by dissipating the electrical energy by means of an electrical resistor.

[0013] The immersion heating element can be immersed in, or capable of being immersed in, the molten metal present or to be produced in the melting furnace, for example along at least half its length (e.g., at maximum fill level). The immersion heating element can generally be elongated and / or cylindrical and / or rod-shaped.

[0014] The immersion heating element may include ceramic components, in particular a ceramic outer shell or jacket. This enables effective heat transfer to the surrounding molten metal. The immersion heating element may also be referred to as an immersion heater or comprise such a heater. The total power output of all immersion heating elements in the melting furnace is at least 50 kW; for melting aluminum alloys, the total power output is at least 150 kW.

[0015] Where reference is made herein to a molten metal present in a melting furnace, it is understood that a person skilled in the art can typically deduce the position and extent of the molten metal to be received from the melting furnace itself. In particular, openings or conduits 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.

[0016] The maximum and minimum fill levels 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 only immersed in the melt to a minimum permissible depth. For instance, the minimum permissible immersion depth cannot exceed one-third or one-quarter of the theoretically available, or in other words, the maximum possible immersion depth.

[0017] Conversely, a maximum fill level 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 fed into the melting furnace but through which no molten metal should flow out of the furnace, can define a maximum possible fill level.

[0018] To reach the fill level in the melting furnace at which the immersion heating element is submerged in the molten metal to its minimum permissible depth, the furnace can be filled with liquid metal from an external furnace or a transport ladle, or by other means. Such an initial filling of the melting furnace may be necessary before the molten metal can be heated or the material to be melted can be heated by the immersion heating element. It may also be necessary before the flow of molten metal can be generated by the circulation device. A side pocket, open at the top and connected to the furnace via a fluid path, can be provided for filling the melting furnace with liquid metal.

[0019] To detect the fill level in the melting furnace at which the immersion heating element is immersed in the melt to its minimum permissible depth, the furnace can be equipped with one or more level sensors. The terms "level" and "fill level" can be understood synonymously here. A level sensor can detect the minimum permissible level of the melt in the 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 authorize the operation of the immersion heating element. If the level sensor detects that the minimum level for operating an immersion heating element is not present, for example, because metal has been removed from the furnace, the authorization to operate this immersion heating element is preferably revoked.Alternatively, a sensor can measure the level of the melt in the melting furnace and transmit an analog signal to a control unit. Preferably, the control unit compares the current level with the minimum permissible level and generates the corresponding signal to enable the operation of the immersion heating element.

[0020] If the melting furnace has a second heating device positioned outside the molten metal, the second heating device can be operated even if, due to the melt level in the furnace, the first heating device, namely the immersion heating elements, has not received operating authorization from a control unit.

[0021] In the same way as described above, the maximum fill level of the melting furnace can be detected, and a control unit can regulate the furnace's operation. For example, at maximum fill level, the addition of molten material can be prevented by the control unit blocking the opening of each charging door, for instance, by not enabling the door openers.

[0022] According to a preferred embodiment, the immersion heating element is surrounded by the flow of molten metal. In particular, the immersion heating element can be positioned in a region of the melting furnace through which the flow of molten metal flows. Additionally or alternatively, it can be immersed in a region of the molten metal where the flow is pronounced and, for example, exhibits a certain minimum velocity. For this purpose, the region can be located in a furnace segment with an inlet opening and an outlet opening, whereby this furnace segment is subject to a defined flow. In other words, the immersion heating element cannot be immersed in a quasi-static region of the molten metal or a region where the flow does not reach a minimum velocity.Several immersion heating elements can be arranged offset in the direction of flow, so that - viewed from the inlet opening of the chamber - they block the flow cross-section of the molten metal flow by more than 20%.

[0023] In particular, 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 (especially 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 of the same thermal conductivity).

[0024] According to the invention, the melting furnace comprises at least one charging opening for supplying the 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, lined with a refractory material. For this purpose, it can have a housing and / or wall sections that surround an interior space of the melting furnace in which the molten metal can be received.

[0025] The melting furnace may be at least partially lined with refractory material. It may consist of, or comprise, open-topped troughs covered by a removable lid. It may consist of, or comprise, areas and / or chambers with a non-removable lid.

[0026] The charging opening can be defined as a targeted penetration in the casing or wall sections of the melting furnace. It can be adapted to the size of the material being charged. The charging opening can have an area of ​​at least 40 cm²; it can also have a size of 6 m², depending on the size of the material being charged (also called the melt). It can be closable, e.g., by means of a door or flap. Through the charging opening, metal can enter the melt directly or first enter or be placed into a charging area of ​​the type described below.

[0027] For example, the charging opening can be a lateral opening in the melting furnace and / or a non-horizontal opening, which facilitates the feeding of metal and reduces the risk of molten metal splashing out. For example, the opening cross-section (or a plane in which it extends) can have an inclination to a vertical plane of no more than 45°.

[0028] Alternatively, the charging opening can be formed by an open section of the furnace's ceiling, and in particular by a furnace chamber (see definition below), meaning that the material to be melted can be fed in, for example, by opening a top cover. The charging opening can therefore also run horizontally or almost horizontally and, for example, have an inclination of no more than 45° to a horizontal plane. Combinations of differently oriented charging openings (e.g., horizontal and vertical) are also possible.

[0029] The melting furnace, and in particular a single furnace chamber, can have several charging openings, especially one large and one small charging opening of the type described above. This can be, in particular, a furnace chamber containing the first or the second heating device.

[0030] The charging opening does not necessarily have to be located in a furnace chamber, or at least not in a furnace chamber with a primary or secondary heating element. It can, for example, also be provided in a melting channel with a reduced cross-section between two furnace chambers.

[0031] In general, the melting furnace can be configured to melt a single, continuous piece of metal weighing up to 1200 kg, for which a suitably sized charging opening must be provided. The melting furnace can also be additionally or alternatively configured to melt a single piece of metal fed into the furnace from a collection container. Additionally or alternatively, the melting furnace can also be configured to melt lumpy material. This includes parts that are individually fed into the molten metal in the furnace, as opposed 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 configured to melt metal shavings.These can also be fed in via a comparatively small feed opening and / or as bulk material.

[0032] 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 moves from the immersion heating element towards the feed opening. This has the advantage that solid metal fed through the feed opening is not moved directly towards the immersion heating element by the molten metal flow, but potentially 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 towards a feed opening, from there to the immersion heating element, 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 heating elements not being positioned in the immediate vicinity of the feed opening.

[0033] Alternatively or additionally, the molten metal flow can be generated in such a way that it flows towards or around the feed material in the molten state. This can be achieved, for example, by appropriate positioning or orientation relative to a feed opening of the type described herein. The molten metal flow can, for example, flow below and / or directly past a feed opening, so that metal added through the feed opening enters the molten metal flow. The flow towards and, in particular, around the feed material accelerates its melting.

[0034] In particular, the molten metal flow can direct at least a portion of the supplied material towards it at a flow velocity that corresponds at least to an average flow velocity, and 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 narrowing of a melt channel, particularly annular in shape, can be provided in the area of ​​a charging opening.

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

[0036] According to another aspect, the first heating device is positioned in a furnace chamber, and the recirculation device is optionally positioned outside this furnace chamber but fluidly connected to it. For example, the recirculation device can draw molten metal from the furnace chamber via a melt channel or other fluid-conducting connection and, under pressure, return it to the furnace chamber (preferably, however, to another part of the furnace chamber, e.g., through an inlet opening). The molten metal preferably flows to, and in particular along, a charging 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, comprising an inlet and an outlet (e.g., in the form of an inlet and an outlet opening) and exhibiting a widening of the maximum flow cross-section of at least 20% relative to these inlet and outlet areas. The flow cross-sections considered here can refer to cross-sections defined by the structure, i.e., theoretically or structurally possible flow cross-sections. Alternatively, the 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 area can have a volume increase of at least 20% compared to melt channels connected with the inlet and outlet area (and / or chambers or areas directly adjacent to them), in particular with respect to 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 pass from one furnace chamber to another through an opening, in particular forming an inflow region and / or a reduction in the cross-sectional area of ​​the flow path compared to the furnace chamber. The cross-sectional area of ​​the inflow region may not exceed 80% of the cross-sectional area of ​​the flow path upstream and / or downstream of the inflow region.

[0040] A portion of the molten metal contained in a furnace chamber can be separated from other portions of the molten metal by process engineering in such a way that a process (e.g., holding or remelting) in the furnace chamber does not directly affect a process outside of that furnace chamber. For example, heat generated within the furnace chamber cannot directly affect the area outside the furnace chamber, but can only be transferred via the molten metal flowing out of the furnace chamber.

[0041] In the case of multiple furnace chambers, these can be separated from one another by at least one wall section (or, in other words, at least one partition). This wall section or partition 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 bounded, at least partially, by the common wall section. Any furnace chamber described herein can be bounded, at least partially, by at least one outer wall of the melting furnace, the outer wall generally defining a boundary with the furnace's surroundings.

[0042] Alternatively, a furnace chamber can 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 can, for example, be comprised by a single segment or a single module of the type disclosed herein. This connection can comprise, or be realized as, a flow channel, an open trough, or a furnace chamber dimensioned as a flow channel.

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

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

[0045] Unlike tubular or upward-opening and generally elongated melting channels, the furnace chamber can be designed to receive the molten metal, forming a large-area melt pool. The area of ​​the melt pool can be formed by an exposed, and in particular horizontal, surface of the molten metal. The dimensions of this area can be larger than the cross-sectional area of ​​the melt pool, which includes a vertical axis.

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

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

[0048] Any furnace chamber disclosed herein may 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 for transferring the molten metal, rather than receiving the molten metal for heating by any heating device described herein. However, troughs in which melting takes place are also conceivable. A trough may generally be characterized by the fact that the flow cross-section of the furnace before and after it can be at least 50% larger (for example, over a length of at least half a meter). The trough may be permanently open at the top or at least temporarily closable by a liftable cover.

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

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

[0051] Preferably, the molten metal flow passes through the annular channel in a circulating manner, particularly as an open channel flow.

[0052] The annular channel can encompass any furnace chamber mentioned herein. In other words, any furnace chamber mentioned herein, and indeed any other molten area of ​​the melting furnace, can form a segment of the annular channel. Outside the annular channel, no molten metal flow can exist in the melting furnace, in particular no continuous and / or circulating molten metal flow.

[0053] The melting furnace has an interior area surrounded by the annular channel. In particular, the interior area can be completely enclosed by the annular channel, e.g., along the direction of rotation of the annular channel. Consequently, a furnace housing surrounding the annular channel can also completely and preferably fully encircle the interior area. The interior area can be open at the top and accessible from there (e.g., by ladders, stairs, or cranes). The interior area is unobstructed. It can define a work area, e.g., for maintenance work. In particular, it can be free of other furnace components. For example, only components permanently attached to a furnace housing can project into the interior area. The interior area can be sufficiently large to allow a person to be present in it. It comprises an area of ​​at least 1 m² and preferably at least 2 m².

[0054] During furnace operation, various tasks and operations can be performed from the outside, i.e., from the sides of the furnace housing facing away from the interior. Such externally performed measures can include, in particular, charging the furnace and removing molten metal. Additionally or alternatively, these measures can include skimming solid impurities from the melt surface, sampling the melt, alloying, or refining.

[0055] Inside the furnace, components such as lid lifting devices with drives, cable ducts, and / or electrical junction boxes (in other words, electrical fuse boxes or switch boxes) may be installed. These interior furnace components do not obstruct work carried out from the outside. In particular, access to the melt is unimpeded and is not hindered or blocked by interior furnace components. Conversely, the interior furnace components are not soiled or damaged by work carried out outside.

[0056] The annular channel can comprise a plurality of modules through which the molten metal flow passes. The modules can be arranged sequentially and / or in series along a flow direction of the molten metal. The modules can be arranged and interconnected in such a way that they jointly define the annular channel disclosed herein. Optionally, further modules can also be provided, which, for example, enable the supply or removal of molten metal to or from the annular channel. These modules need not necessarily be subject to the circulating flow of molten metal, in particular not continuously.

[0057] The modules can form independently manageable, transportable, and / or manufactured parts of the melting furnace. Each module can comprise at least a section of a furnace housing. Each module can be supported independently on a base. When connected in series, the modules can contact at least one adjacent module and, in particular, be connected to it, for example, by a mechanical connection or by welding. The modules can be connected in series along the direction of flow of the molten metal. Each module can comprise and / or completely form a section (in other words, a channel segment) of the annular channel, with this section extending along the direction of flow of the molten metal. 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, and at least one outlet opening. The at least one inlet opening can be provided for introducing molten metal from an adjacent module, in particular from an outlet opening of that module, and is preferably 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 encompass a corresponding supply area. In particular, this further inlet opening can be designed as a branch channel or be fluid-conductingly connected to one in order to supply molten metal to the melting furnace. The inlet opening and outlet opening can be located opposite each other along the flow direction of the molten metal flow.The inlet opening allows molten metal to flow from a preceding module (in the direction of flow). The outlet opening allows molten metal to flow into a subsequent module (in the direction of flow). A module can therefore be traversed from the inlet opening to at least one outlet opening. Alternatively, an outlet opening can be designed as a branch channel or be fluid-conductingly connected to one in order to discharge molten metal from the melting furnace.

[0059] Each module can be fluid-tightly connected to at least two other modules to transfer the molten metal flow between them. Each module can be connected, for example, to a first module via an inlet opening and to a second module via an outlet opening. This is particularly relevant for modules that together form an annular channel as disclosed herein and / or are arranged in series in the flow direction. It is also possible that there are additional modules (e.g., for liquid metal supply or melt extraction) 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, for example, the module flanges can be bolted, welded, or otherwise joined together. The connection can be sealed or sealed. Each module can preferably be connectable to any other module. Consequently, the modules can have uniform interface areas for connection with other modules. These interface areas can be characterized, for example, by uniform dimensions and / or shapes, in particular by uniform flanges for creating a connection with other modules.

[0061] The modules can be connected, at least partially, only at the final installation site, which is where the melting furnace will be used. This facilitates the transport of the melting furnace to the installation site. In particular, the modules can have dimensions suitable for standard truck or shipping container loading volumes to simplify transport. For example, the modules can have a cross-sectional area (width x height) of less than 12 m² for road transport or less than 7.2 m² for transport by sea container.

[0062] Each module can comprise a furnace casing, particularly one made of steel. Each module can be refractory-lined, or in other words, have a refractory lining. This lining is preferably applied, for cost reasons, before the module is erected at the furnace site and / or before the module is assembled to construct a furnace. For example, pre-cured linings can be installed in the modules, or the modules can be cured or dried within the modules before they are erected and connected at the furnace site. This reduces the required heating of the furnace during the initial start-up phase at the site. Alternatively, the modules can be refractory-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 assembled to construct a melting furnace, for example, to meet specific furnace capacities. By selecting and combining modules from a single group, several different melting furnaces can theoretically be produced. This reduces the manufacturing costs of each individual furnace. As explained below, using at least two modules offers particular advantages in terms of reduced transportation costs. A larger number of modules, especially at least four, allows for different arrangements and connections to create various melting furnace layouts. For example, the sequence of modules along the metal flow axis can be varied to generate different layouts.

[0064] Accordingly, in an advantageous embodiment, the modules can be used in different layouts or designs of a melting furnace, or, in other words, assembled and connected according to such different layouts or designs. Put another way, the modules are preferably configured such that different properties and / or capabilities of the melting furnace can be achieved through different combinations or sequences of the modules. For example, by varying the number of modules, different furnace sizes or capacities can be produced with limited effort. For example, the melting capacity 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 a circulating pump; module with a charging opening; module with an 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 withdrawal. According to one embodiment, the melting furnace comprises at least one module according to each of 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 withdrawal, a module, which preferably defines a section of an annular channel disclosed herein, can comprise a conventional tapping valve.In principle, a module can also embody or include two of these examples, for example by including both a circulation pump and immersion heating elements.

[0066] According to a training course, the following applies to the dimensions of each module or at least a majority of the modules: the height is less than or equal to 2.9 m (especially for transport in a sea container) or the height is less than or equal to 3.8 m (especially for road transport); and / or at least one first (e.g. shorter) horizontal dimension is less than or equal to 2.5 m (especially for transport in a sea container) or is less than or equal to 3 m (especially for road transport); and / or 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.

[0067] The first horizontal dimension can be, for example, a width, and / or the second horizontal dimension can be, for example, a length. The first and second horizontal dimensions can be essentially or completely orthogonal to each other.

[0068] For example, a module with an opening for receiving rejected components or recycled material from a forming process for remelting may be larger than several or all other modules. This module may be dimensioned for road transport and / or approach or exceed the upper limits defined above (and / or, in particular, exceed the lower limits). All other modules, however, may at most approach the lower limits defined above.

[0069] The modules may have a connection 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 connection area may, for example, include a flange or interface area of ​​the type discussed above. This may be particularly relevant in the context of variants in which, as described above, the modules each comprise a furnace housing lined with a refractory material.

[0070] In a simple case, the melting furnace comprises only two modules, in which the molten metal circulates in a ring channel formed by the modules. Each module has a connection point, e.g., a flange, at its inlet and outlet openings. The flanges are preferably located on the longitudinal side of the modules (e.g., a longer or the 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 shipping containers, while the melting furnace assembled from the modules is wider than 2.5 m.

[0071] This melting furnace can be easily enlarged or expanded by adding further modules between the two modules described above. For example, the melting capacity of the furnace can be increased by adding one module with immersion heating elements. The melting capacity can be increased as desired by adding further modules with immersion heating elements.

[0072] In a further training, the circulation device includes 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.

[0073] According to a further embodiment, the heating device is arranged in a section of the annular channel where 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 a correspondingly continuous flow through said section. In other words, no volume fractions of the molten metal flow can remain permanently in this section and / or flow through this section at a significantly reduced velocity (for example, at a velocity of less than half the maximum flow velocity of the molten metal flow in this section). The molten metal can flow continuously and completely through the section containing the heating device, so that a correspondingly large volume of the molten metal is heated by the heating device.In particular, the section encompassing the heating element can be free of projections directed towards the center of the channel and / or free of undercuts. Such shape features could otherwise impede the preferably complete melt exchange during flow through this section.

[0074] Additionally or alternatively, the molten metal flow in the section encompassing the heating device (and / or immediately upstream of this section) can exhibit a substantially uniform (or constant) flow velocity across its cross-section. In particular, the velocity profile within this cross-section can show 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.

[0075] According to a further embodiment, the heating device comprises a plurality of immersion heating elements, each immersion heating element being arranged at least partially outside the flow shadow of at least one other corresponding immersion heating element (or the at least one other immersion heating element). In particular, each immersion heating element can be arranged at least outside the direct flow shadow of at least one or all other immersion heating elements.

[0076] The flow shadow of an immersion heating element can form or encompass a region into which molten metal cannot enter without being deflected by the immersion heating element (in particular, deflected along its outer surface). Viewed along a flow direction of the molten metal stream impinging on an immersion heating element, the flow shadow may be located at the rear of the immersion heating element. The molten metal stream may, conversely, impinge on the immersion heating element at its front. The flow shadow may include a virtual extension of a flow axis of the molten metal stream impinging on the immersion heating element, with this extension intersecting the immersion heating element.

[0077] 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 shadows. To be positioned 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 relative to the other immersion heating element, in particular at least partially or completely.

[0078] According to a further development, the melting furnace comprises at least a second heating device that is positioned or positionable outside the molten metal. The second heating device is preferably configured to supply heat to the molten metal and / or to a metal being 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 also be positioned at a horizontal distance from the charging opening and, in particular, behind the charging opening when viewed in the direction of flow. Alternatively, it can be positioned directly opposite and above the optional charging ramp.

[0079] Providing a second heating element 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, particularly when circulating, after optionally flowing around the immersion heating element can thus be prevented, enabling a more energy-efficient design and / or operation of the immersion heating element. The second heating element can be located in a furnace area that is already required for furnace operation, but where the provision of immersion heating elements is not necessarily preferred, for example, near a charging opening.

[0080] The first and second heating devices can be spaced apart along the flow path of the molten metal. The first heating device may, for example, be configured to generate sufficient heat to melt the metal. The second heating device, on the other hand, may not be configured to generate such a high heat. Instead, it may generate less heat, but enough to keep the molten metal warm (especially molten).

[0081] 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 and second heating devices can be configured to generate heat independently of each other. Additionally or alternatively, they can be controlled and / or operated independently with respect to their respective heat generation. According to one embodiment, the second and first heating devices comprise independently operable heat sources. Optionally, both the first and 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.

[0082] In particular, the second heating device can be designed as a radiant heater and, furthermore, especially as a ceiling-mounted radiant heater (or ceiling-mounted radiant heater), or at least comprise such a heater. This heater can be positioned opposite the molten metal and / or directed towards it. The radiant heater can be electrically operated. The ceiling-mounted radiant heater can be arranged in a ceiling area of ​​the melting furnace, in particular on an inner ceiling extending substantially parallel to the molten metal. The ceiling area can be fixed or, in other words, not openable.

[0083] In general, the heating device can comprise at least one heating element that irradiates and thereby heats the surface of the molten metal from above, particularly where more than 50% of the heat transfer to or into the melt occurs by 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. Multiple heating elements, and especially heating rods, can be arranged in a common plane. This plane can, in turn, be horizontal and / or parallel to the surface of the molten metal.

[0084] Alternatively, the second heating device can include at least one gas burner. This burner can be specifically designed and positioned to heat solid metal in a charging area, or to heat the molten metal. Multiple second heating devices can also be provided, and these devices may differ from one another. For example, the melting furnace can include both a radiant heater (especially a ceiling-mounted heater) and a gas burner.

[0085] The radiant heater enables efficient continuous operation and, in particular, helps to maintain the molten metal at a desired temperature. A gas burner can allow for particularly rapid heating of solid metal before it is added to the molten metal, but it can also reliably heat an already existing molten metal.

[0086] In one variant, the second heating element is positioned vertically higher than the immersion heating element. This allows for reliable heating of the molten metal without the second heating element having to be immersed in it. In particular, the second heating element can be positioned vertically above the maximum possible fill level.

[0087] In one embodiment, the second heating element is arranged at least at the same vertical height as, or vertically higher than, a charging opening, and in particular higher than any charging opening of the melting furnace. This ensures a particularly reliable positioning of the second heating element outside the molten metal.

[0088] According to another aspect, the circulation device, as mentioned above, comprises a mechanical or electromagnetic pump or, alternatively, a magnetic or electromagnetic stirrer. The magnetic or electromagnetic stirrer can be located outside the melting furnace and / or a housing or furnace chamber. At least part of the stirrer (e.g., a magnetic or electromagnetic drive unit) can be located, for example, below a furnace chamber or furnace housing.

[0089] An alternative or additional embodiment provides that the circulation device includes a mechanically driven stirrer as an example of 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.

[0090] A preferred circulation device is a mechanical or an electromagnetic pump.

[0091] A further development provides that the second heating element and the first heating element 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 an area through which flow can pass or around them. Preferably, the furnace chamber (hereinafter also referred to as the first furnace chamber) containing the first heating element 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) containing the second heating element. For example, the (e.g., average or maximum) flow cross-section of the first furnace chamber may be no more than 80% or even no more than 50% of the (e.g., average or maximum) flow cross-section of the second furnace chamber.This allows for the desired flow around at least one immersion heating element. Furthermore, this allows the surface area of ​​the molten metal in the second furnace chamber to be specifically increased for effective heat transfer by the second heating device, which is positioned outside the melt.

[0092] 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 the metal to be melted. This can be the only charging opening of the melting furnace or one of several charging openings. In the latter case, it is preferably not the smallest charging opening of the melting furnace, but for example the largest or at least one that is larger than average.

[0093] 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.

[0094] 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.

[0095] In general, the cross-section of the inlet area to the furnace chamber containing the second heating element can be smaller than the cross-section of an outlet area of ​​this furnace chamber. This allows flow velocities near the inlet area to be increased, ensuring that solid metal parts there are thoroughly surrounded by flow with high heat transfer per unit of time.

[0096] Furthermore, the inlet area of ​​the furnace chamber, which includes the second heating element, can be located closer to the charging opening of this furnace chamber (also referred to here as the second charging opening) than the outlet area of ​​this chamber. This proximity can be measured along a flow path and, in particular, as the distance traveled along this flow path. This also ensures that the supplied metal parts are exposed to high flow velocities and are melted accordingly quickly.

[0097] In this context, it may also be provided that the (first) furnace chamber, in which the first heating device is located, includes a smaller loading opening than the loading opening of the furnace chamber (second furnace chamber) in which the second heating device is located. Both furnace chambers can therefore have loading openings, but the furnace chamber with the first heating device may have a smaller one, so that, for example, only small metal parts can be fed into it. This also helps to reduce the risk of damage to the immersion heating element from solid metal. In particular, the cross-sectional area of ​​the loading opening in the first furnace chamber may be less than half the size, or less than one-tenth, or less than one-hundredth of the cross-sectional area 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 orientation of the circulation device) such that it flows from an outlet area of ​​the (first) furnace chamber, which contains the first heating element, towards an inlet area of ​​the (second) furnace chamber, which contains the second heating element. It can also flow from an outlet area of ​​the second furnace chamber towards an inlet area of ​​the first furnace chamber. This represents an advantageous circulation direction for the molten metal flow, ensuring effective metal melting with a low risk of damage to the immersion heating element from collisions with solid components.

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

[0100] In one embodiment, the recirculation device is positioned near an inlet area of ​​the furnace chamber containing the second heating element and / or opens into this inlet area, particularly in that the recirculation device is positioned outside the furnace chamber containing the second heating element. This allows solid metal supplied to the second furnace chamber to flow around it at high pressures and / or high velocities, enabling rapid melting. Conversely, this reduces the risk of the recirculation device circulating molten metal containing solid particles, thus minimizing the risk of damage to the recirculation device. In principle, it can also be provided that solid metal supplied to the first furnace chamber can flow around it at high pressures.

[0101] According to one embodiment, the circulation device is arranged in the furnace chamber that contains 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] Another variant provides for the generation of a molten metal flow such that it flows from the first heating device towards the circulation device and from the circulation device towards the second heating device. This can facilitate the melting of solid components in the molten metal, which is kept warm by the second heating device, before they reach the first heating device.

[0103] Another variant proposes generating the molten metal flow in such a way that it flows from the first heating element towards the circulation element and from the circulation element towards a charging opening of the second furnace chamber (second charging opening). This can facilitate the melting of solid components in the furnace chamber with the second charging opening and, through convective heat transfer, render the second heating element unnecessary.

[0104] The melting furnace can have at least one impurity collection chamber through which the molten metal flows, and 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 includes, for example, a drain valve that can be opened to allow impurities that have settled in the bottom area to flow out (or be drained).

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

[0106] In particular, the impurity collection chamber can be permeated by a volume of molten metal before it enters the first furnace chamber. This allows impurities to be retained within the impurity collection chamber before they can adhere to the immersion heating elements or otherwise damage them.

[0107] Additionally or alternatively, the impurity collection chamber can have an inlet and an outlet, and a bottom area (or, in other words, a vertically recessed area or depression) that is lowered at least relative to the outlet for collecting impurities that settle there. Impurities in the incoming molten metal can therefore sink into the bottom depression, especially since this depression can cause a local reduction in flow velocity.

[0108] The inlet area can have an opening cross-section extending to a bottom area of ​​a furnace chamber located upstream of the contaminant collection chamber. This furnace chamber could be, for example, the first or the second furnace chamber.

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

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

[0111] Consequently, one embodiment provides that the impurity collection chamber has an outflow area with an opening cross-section, wherein the 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 of the impurity collection chamber (in particular, directly upstream). 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] For any contaminant collection chamber, to ensure an effective cleaning function, it may be the case that its inlet area is closer to a feed opening than its outlet area.

[0113] In one embodiment, the melting furnace comprises a first impurity collection chamber of the type described above, with a recessed bottom area for collecting impurities suspended in the molten metal. This melting furnace also comprises a second impurity collection chamber for collecting impurities of the type described above that float on the surface. The first and second impurity collection chambers are preferably designed to be sequentially permeated by the flow of molten metal. This enables particularly reliable purification of the molten metal. Alternatively, the two embodiments of the impurity collection chambers are combined in a single chamber. In particular, these two impurity collection chambers can be positioned between the second and 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 designed 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 bottom area of ​​the melting furnace and / or towards the molten metal to be received. The charging area can adjoin a charging opening and / or be accessible via it. Metal to be melted can be supplied via the charging opening and, for example, placed 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 using 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 designed to heat the metal taken up in the charging area before it enters the molten metal. This can be achieved in particular by supplying heated air from another area of ​​the furnace, the other area being, for example, positioned near the second heating device, especially if this is designed as a ceiling-mounted radiant heater 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 towards a charging area as described above, a device for circulating the furnace atmosphere may be provided. This device may, for example, include a blower or a fan.

[0117] A further development provides that the recirculation device (viewed, for example, along the flow of molten metal) 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 may, in particular, be encompassed by the first or second furnace chamber of the type disclosed herein. For example, the recirculation device may be located no more than 2 m or no more than 1 m away from the charging opening and / or the charging area when viewed along the flow of molten metal. This increases the flow velocity of the molten metal near the charging opening and / or the charging area. The supplied solid metal is therefore surrounded by liquid melt at a higher velocity, which allows for a higher heat input into the solid metal per unit time.

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

[0119] In a second furnace chamber through which the molten metal flows, the molten metal 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 lumps of material to the molten metal and is arranged so that the molten metal flows around the immersed material. To achieve effective heat transfer and / or to allow for the immersion of large lumps of material, the surface area of ​​the molten metal in the second furnace chamber is preferably larger than in the first furnace chamber. The molten metal circulates between the furnace chambers under the influence of the circulation device. The circulation device can also be arranged along a flow path between the furnace chambers.

[0120] It should be noted that multiple circulation devices may be provided, for example, each in a separate furnace chamber. Multiple primary and / or secondary heating devices may also be provided, each in a separate furnace chamber. For example, multiple furnace chambers may 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 at least a temporary (or even section-by-section) reduction in the flow cross-section (e.g., by more than 20% compared to an upstream region) can be located upstream of a feed opening of 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 feed opening, the flow cross-section can increase again, for example, to the size upstream of the aforementioned region with the reduced flow cross-section. The region with the 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 feed opening can flow around it at an increased velocity and thus experience a higher heat input per unit of time.In one variant, a region with a corresponding reduction in the flow cross-section is located upstream of a majority of, and in particular all, feeding openings.

[0122] A further development provides for a side 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 offset laterally from at least one furnace chamber. This pocket can be filled in the manner described above, particularly for the initial filling of the melting furnace with molten metal.

[0123] As also described above, the melting furnace can be equipped for level detection, or in other words, melt level monitoring. For this purpose, it can have a control unit and a sensor configured to measure the level of the melt in the 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 include detecting the presence or absence of melt at this height, especially in

[0124] This is a purely binary form of 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, perform a distance measurement to a molten surface. A further development of the melting furnace includes at least one bottom weir at the bottom of the annular channel. When the furnace is emptied of molten metal, a residual quantity may remain in the furnace up to a certain height for various reasons. After the furnace's heating elements are switched off, this molten metal solidifies at the bottom. This results in volume contraction. In a melting furnace with 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 the expected level of any solidifying residual molten metal in the furnace.Therefore, it reduces the pressure on the refractory lining. For this purpose, at least one bottom weir, viewed along the extension of a channel's side wall, is positioned such that an inner corner of the channel no longer exists at the bottom. Any bottom weirs can be positioned so that a solidified molten metal plate (e.g., viewed along a flow axis) located between two bottom weirs has an almost rectangular shape, particularly when viewed from above. Such a rectangular solidified metal plate can then be lifted upwards out of the channel using simple tools.

[0125] Geometrically, the bottom weir defines a height difference (in other words, a step) between (especially when viewed in the direction of flow) the areas of the ring channel adjacent to the bottom weir on both sides. These adjacent areas of the ring channel can run at an angle of more than 45° to each other, particularly at an angle of approximately 90°. Consequently, the bottom weir can be positioned in, or adjacent to, a deflection, bend, or corner section of the ring channel, as explained below, where the direction of flow of the molten metal is not straight.

[0126] The bottom weir can reduce the height of a correspondingly curved or deflected wall surface of the annular channel, along which the molten metal flows, due to the difference in elevation. This is particularly advantageous when the molten metal solidifies, which can lead to increased stresses on such non-straight wall surfaces.

[0127] The bottom weir can have a maximum height above the bottom that corresponds to at least 10% and preferably between 15% and 40% (e.g., 20%) of the 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.

[0128] According to one variant, the bottom weir has a connecting channel, which is designed, for example, as a depression or groove and / or which is located at the same level as the bottom of the adjacent areas of the ring channel and connects these areas in a way that conducts the molten metal. This allows the molten metal to flow completely from an area upstream of the bottom weir to an area downstream of the bottom weir, for example, in the direction of flow of a circulating molten metal.

[0129] In other words, a bottom weir can have a connecting channel roughly in its center between the adjacent sections of the annular channel, thus linking these sections in a way that conducts the molten metal. When the furnace is emptied, the molten metal can flow through this connecting channel. This has the advantage that the remaining liquid from both sections of the annular channel—namely, from the areas before and after the bottom weir—can flow to a common point where it is drawn from the furnace. This reduces the number of points where a device for removing the remaining molten metal needs to be provided. While the connecting channel can create an inner corner in the annular channel, damage to this corner caused by contracting molten metal 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's side walls.

[0130] According to a further development, the melting furnace also has a furnace housing that (at least partially) delimits the annular channel, with at least one lid and a lid lifting device configured to lift the lid to provide access to the annular channel. A lid lifting device can include 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) can be attached to the lid and lifted together with the lid. In the raised position, the immersion heating element can be positioned at least partially or completely outside the furnace housing, for example, for maintenance purposes.

[0131] The lid can be lifted vertically and / or in a straight line, unlike, for example, a lid that simply swings open. This allows heat radiation to be spatially limited to an area above the furnace housing, which facilitates maintenance work.

[0132] The lid lifting device can be located on the side of the melting furnace facing the interior. Accordingly, the lid lifting device can be serviced from inside the furnace.

[0133] According to a further development, the annular channel has at least one deflection region in which the flow direction of the molten metal is deflected by at least 45°, preferably by approximately 90°. The deflection region can form a corner region or a curved region of the annular channel. In particular, it can connect two essentially straight channel segments that run at an angle to each other.

[0134] Side wall sections of the annular channel, located upstream and downstream of the deflection zone, can transition smoothly into one another or be chamfered. In particular, these side wall sections can be enclosed by an inner side of the annular channel closer to the interior of the melting furnace, thus forming inner side walls as opposed to outer side walls. The deflection zone can therefore also be internal and / or define an internal deflection or an internal corner region. Alternatively or additionally, side wall sections enclosed by an outer side of the annular channel furthest from the interior of the melting furnace can transition smoothly into one another or be chamfered. In other words, the annular channel, and especially its inner walls, can have rounded or chamfered corner regions, for example, in a deflection zone as described above.Providing a chamfer can involve connecting two wall sections running at a large angle to each other, e.g., 90°, by an intermediate section, which is preferably flat and runs at a smaller angle to each of these wall sections. This results in a less sharp transition between the wall sections.

[0135] 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.

[0136] The invention also relates to a melting furnace for melting metal, including: a molten metal taken up in the melting furnace; a first heating device with at least one electrically heated immersion heating element; a circulation device which is set up to generate a flow of molten metal around the immersion heating element.

[0137] All features, developments and variants of a melting furnace and its characteristics disclosed herein may also be provided for in this melting furnace with incorporated molten metal.

[0138] The invention further relates to a method for melting metal using a melting furnace according to any aspect disclosed herein, the method comprising, inter alia: Generating the flow of molten metal by means of the circulation device, so that the flow of molten metal surrounds the immersion heating element.

[0139] The method may include all further steps and measures to provide any operating states, interactions, and functions of a melting furnace disclosed herein. For example, the method may also include the step of feeding metal to be melted through a charging opening, the charging opening being designed and arranged according to any variant described herein.

[0140] The invention also relates to a method for manufacturing a melting furnace with an annular channel (for example, configured according to any aspect disclosed herein) in which a molten metal can be circulated, the method comprising: connecting individual modules to form at least one section of the melting furnace, wherein each module comprises a channel segment of the annular channel and, in particular, an inlet opening and at least one outlet opening. The modules and the melting furnace can be configured according to any aspect disclosed herein. The modules can be selected and / or combined from a plurality of modules that can be installed in principle.

[0141] Exemplary embodiments are described in more detail with reference to the accompanying figures. These relate to the Figure 1-6 General embodiments that are helpful for understanding the claimed invention, but are not themselves embodiments according to the invention.

[0142] They show Figure 1: A schematic representation of a melting furnace for melting metal. Figure 2: A schematic representation of a melting furnace for melting metal according to a further embodiment. Figure 2': A schematic representation of a possible alternative arrangement of the immersion heating elements. Figure 2 in the melting furnace of Figure 2 Figure 2"a schematic representation of a possible further alternative arrangement of the immersion heating elements of the Figure 2 in the melting furnace of Figure 2 Figure 2‴a schematic representation of a possible further alternative arrangement of the immersion heating elements of the Figure 2 in the melting furnace of Figure 2Figure 3: A schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 4: A schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 5: A schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 6: A schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 6: The embodiment of the Figure 6 , wherein gas burners are provided as the second heating elements instead of heating rods (Figure 6) – the embodiment of the Figure 6, wherein both heating rods and gas burners are provided as second heating elements. Figure 7 shows a schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 8 shows a schematic, perspective view of a melting furnace. Figure 9 shows the melting furnace of the Figure 8 in a section along a through the in Figure 8 The lines A and B drawn in the plane define Figure 10 a section of the Figure 8 or Figure 11 shows a section through the second furnace chamber of the melting furnace. Figures 8 to 10 Figure 12 shows a section through the second furnace chamber of the melting furnace. Figures 8 to 11 , wherein a loading ramp is provided Figure 13 shows a section through the second furnace chamber of the melting furnace of the Figures 8 to 12 , wherein a charging ramp with gas burner is provided Figure 14 shows a section through the second furnace chamber of the melting furnace of the Figures 8 to 13, wherein a loading ramp and a gas circulation device are provided. Figure 15 shows a section through the second furnace chamber of the melting furnace. Figures 8 to 14 , wherein gas burners are provided instead of electric heating elements. Figure 16: a schematic representation of a possible embodiment of a melting furnace for melting metal according to a further embodiment. Figure 17: a sectional view of a melting furnace for melting metal according to a further embodiment. Figure 18: a representation of a subdivision of the melting furnace made of Fig. 17 Fig. 19 shows a representation of a melting furnace according to a further embodiment with an annular melting channel and division into two modules. Fig. 20 shows a representation of a melting furnace according to a further embodiment with an annular melting channel and division into four modules. Figure 21 shows a view of a single module of the melting furnace. Figure 17 - 18, wherein the individual module includes a lid lifting device.

[0143] Figure 1 Figure 100 shows a schematic representation of a melting furnace for melting metal. The melting furnace is particularly suitable for melting metals with a melting point below 900 °C.

[0144] The melting furnace comprises a first furnace chamber 110. The melting furnace 100 has a first charging opening 140. The charging opening 140 is designed for supplying 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 the charge, can be introduced from an environment 1 surrounding the melting furnace 100 into the first furnace chamber through the charging opening 140 when the charging opening is open. The charging opening 140 can be closed by a charging door 141. A furnace interior comprising the furnace chamber 110 can be closed off from the environment surrounding the melting furnace, for example, by the charging door 141. The furnace interior can include further furnace chambers and / or melting channels.

[0145] In particular, areas of the melting furnace 100 that come into contact with molten metal are lined with refractory material. For example, furnace chamber 110 is lined with refractory material. The refractory-lined areas, including 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, molten metal in the melting furnace, especially in 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).

[0146] The melting furnace 100 is electrically heated. The melting furnace 100 comprises a first heating unit 130 with an electrically heated 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 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 contained in the melting furnace 100 is located in the furnace chamber 110. The immersion heating element 131 is surrounded by the molten metal 101. The molten metal 101 has a temperature of approximately 750°C.The melting furnace 100 comprises a circulation device 120, which is configured to generate a flow of molten metal, at least partially represented by the arrows 101', within the melting furnace. The circulation device 120 includes a pump 121 for conveying the molten metal 101. The circulation device 120 is arranged and configured such that the flow of molten metal 101' circulates between the immersion heating element 131 and the pump 121. The pump 121 can be arranged in the furnace chamber 110 or outside the furnace chamber 110, as shown in Figure 1. Figure 1The pump 121 is not restrictive outside of furnace chamber 110. It can be located in a second furnace chamber 111. Alternatively, the pump 121 can be fluidly connected to furnace chamber 110 via melt channels. The melt channels are lined with refractory material. The melt channels can be designed, at least partially, as closed tubes and / or, at least partially, as open channels. The melt channels can be heated.

[0147] The pump 121 can be arranged next to the immersion heating element 131 such that a suction port of the pump 121 is located away from the immersion heating element 131 and a discharge port of the pump 121 is located towards 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 discharge 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 such a distance from the immersion heating element 131 that the pump 121 can generate a melt flow that at least partially surrounds the immersion heating element 131.

[0148] In particular, the circulation device 120 and the first heating device 130 are arranged such that the flow surrounds 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-around region of 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-around region 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 circulating the molten metal 101.

[0149] With pump 121 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 drawn in by pump 121 and circulated. The molten metal 101 flows through the furnace chamber 110 with the immersion heating element 131 and is thereby heated. If material to be melted has been introduced into the furnace chamber 110 via the charging opening 140, the furnace chamber 110 contains molten material. With pump 121 switched on, the molten metal flows around the material in the furnace chamber 110 and heats it, causing it to melt.

[0150] 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 and melting channels.

[0151] Alternatively or additionally, further furnace chambers can be provided, each of which may have a charging opening. These further furnace chambers can be designed and arranged such that the molten metal 101 is circulated by the pump 121 in such a way that it flows through them. Connecting channels and / or openings between the furnace chambers can be designed such that the charge material from one furnace chamber is not moved into a subsequent furnace chamber (in the direction of flow) or is only moved when it reaches a maximum size. The further charging openings of the additional furnace chambers can be smaller than the charging opening 140. The additional furnace chambers can also be suitable for receiving and melting charge material, for example, in the form of metal shavings. The furnace chamber 110 and the charging opening 140 can be designed, in particular, to receive larger charge material.The larger items to be loaded can, for example, consist of metal objects, each with 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 items to be loaded can, for example, consist of metal objects, each with a maximum length and / or width of no more than 300 cm and / or no more than 200 cm and / or no more than 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 smaller items to be loaded can, for example, consist of 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.

[0152] The exemplary embodiment of the Figure 1 may also have a second heating device (not shown in Figure 1 , however, below, for example, based on Fig. 6(explained). In particular, the second heating device can be arranged in the area 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 an area 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 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.

[0153] Figure 2shows a schematic representation of a 200 mm melting furnace for melting metal. Figure 2 The melting furnace 200 is shown in a horizontal section through the melting furnace 200 in a top view.

[0154] The melting furnace 200 is particularly suitable for melting metals with a melting point below 900 °C.

[0155] 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 fluidically connected to each other via a first connecting opening 213 and a second connecting opening 214.

[0156] The melting furnace 200 has a first charging opening 240. The charging opening 240 is designed for supplying metal to be melted. The charging opening 240 is arranged on the furnace chamber 211 such that metal to be melted, hereinafter referred to as the charge, can be introduced from the environment 1 surrounding the melting furnace 200 into the second furnace chamber 211 through the charging opening 240 when the charging opening 240 is open. The charging opening 240 has a width of 120 cm and a height of 120 cm. The charging opening 240 can be closed by a charging door 241. An interior space of the furnace, comprising the furnace chamber 210 and the second furnace chamber 211, can be closed off from the environment 1 surrounding the melting furnace by the charging door 240.

[0157] In particular, areas of the melting furnace 200 that are designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 210 and furnace chamber 211 are, at least partially, lined with refractory material. The refractory-lined areas 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 areas 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, molten metal in the melting furnace, in particular in 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.

[0158] The melting furnace 200 is electrically heated. The melting furnace 200 comprises a first heating device 230 with electrically heated immersion heating elements 231, which are 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.

[0159] Furnace chambers 210 and 211 are at least partially filled with molten metal 201, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 211 contains approximately 60% of the molten metal 201 contained in furnace 200. Furnace chamber 210 contains approximately 40% of the molten metal 201 contained in furnace 200. The molten metal 201 has a temperature of approximately 750 °C.

[0160] The melting furnace 200 comprises a circulation device 220, which is configured to generate a flow of molten metal, 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.

[0161] 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 located in the first furnace chamber 210. An intake port of the pump 221 is sealed to the first connecting opening such that molten metal 201 flowing through the first connecting opening flows into the pump 221. A discharge port of the pump 221 faces the immersion heating elements 231. The second connecting opening is located downstream of the immersion heating elements 231, so that the molten metal 201, conveyed by the pump 221, flows through the first furnace chamber 210, passing around the immersion heating elements 231, and then flows through the second connecting opening into the second furnace chamber 211. As the molten metal flows around the immersion heating elements 231, it is heated. This shows 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 described furnace chambers.

[0162] 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 directly next to the immersion heating elements 231 of a second row. This is shown schematically in Figure 2', where the immersion heating elements 231 of the first row are shown as solids and the immersion heating elements 231 of the second row are shown as 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" shown, wherein the immersion heating elements 231 of the first row are shown as solid and the immersion heating elements 231 of the second row are shown as dashed lines.

[0163] The immersion heating elements can be arranged offset in the direction of flow. This can be done in such a way that, viewed from the inlet opening of the chamber, they obstruct the flow cross-section of the molten metal flow by more than 20%, as shown schematically in Figure 2.

[0164] When the molten metal 250 has been introduced into the furnace chamber 211 via the charging opening 240, the molten metal 250 is located in the furnace chamber 211. With the pump 221 switched on, the molten metal 201 flows around the molten metal 250 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 molten metal 250 and towards the suction port of the pump 221, which is connected to the connecting opening 213.

[0165] Alternatively or additionally to a pump 221, the circulation device 220 can include 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 foregoing variants.

[0166] The exemplary embodiment of the Figure 2The furnace may additionally have a second heating device (not shown). In particular, the second heating device may be arranged in the area of ​​the second furnace chamber 211. The second heating device may, in particular, be an electric heating device. In particular, the second heating device may be arranged in an area that does not come into contact with the melt. In particular, the second heating device may be arranged above the melt. The second heating device may comprise second heating elements in the form of heating rods, heating plates, heating panels, or heating coils. Additionally or alternatively, the second heating device may comprise heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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, thus heating the molten material below the second heating elements.

[0167] Figure 3 shows a schematic representation of a 300 mm melting furnace for melting metal. Figure 3 The melting furnace 300 is shown in a horizontal section through the melting furnace 300 in a top view.

[0168] The 300 melting furnace is particularly suitable for melting metals with a melting point below 900 °C. The 300 melting furnace is particularly suitable for melting lumpy material (melt material 350), for example, the size of a car wheel rim.

[0169] 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 310 and the second furnace chamber 311 are fluidically connected to each other via a first connecting opening 313 and a second connecting opening 314.

[0170] The melting furnace 300 has a first charging opening 340. The charging opening 340 is designed for supplying metal to be melted, in particular material 350, in this case, for example, a car wheel rim. The charging opening 340 is arranged on the furnace chamber 311 such that the material 350 can be introduced from the surrounding environment 1 of the melting furnace 300 through the charging opening 340 into the second furnace chamber 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. An interior furnace space, comprising the furnace chamber 310 and the second furnace chamber 311, can be closed off from the environment 1 surrounding the melting furnace by the charging opening door 340.

[0171] In particular, areas of the melting furnace 300 designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 310 and furnace chamber 311 are, at least partially, lined with refractory material. The refractory-lined areas 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, molten metal in the melting furnace, especially in 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.

[0172] The melting furnace 300 is electrically heated. The melting furnace 300 comprises a first heating unit 330 with electrically heated immersion heating elements 331, which are 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.

[0173] Furnace chambers 310 and 311 are at least partially filled with molten metal 301, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 311 contains approximately 20% of the molten metal 301 located in furnace 300. Furnace chamber 310 contains approximately 80% of the molten metal 301 located in furnace 300. The molten metal 301 has a temperature of approximately 750 °C.

[0174] The melting furnace 300 comprises a circulation device 320, which is configured to generate a flow of molten metal, 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.

[0175] 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 located in the first furnace chamber 310. A pressure port of the pump 321 is sealed to the second connecting opening 314 such that molten metal 301 flowing through the second connecting opening first flows through the pump 321. A suction port of the pump 321 is located facing the immersion heating elements 331. The second connecting 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 through the second connecting 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 described furnace chambers.

[0176] 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 only one or two rows of immersion heating elements 331, can be provided. The immersion heating elements 331 of a first row can be offset from the immersion heating elements 331 of a second row. Alternatively, the immersion heating elements 331 of a first row can be arranged one behind the other or in line with the immersion heating elements 331 of a second row. This is shown schematically in Figure 3 As shown. Some immersion heating elements 331 can also be arranged in a downward alignment with each other, and some other immersion heating elements 331 can be arranged offset from each other downwards.

[0177] When the molten metal 350 is introduced into the furnace chamber 311 via the charging opening 340, it is located in the furnace chamber 311. With the pump 321 switched on, the molten metal 301 flows around the molten metal 350 in the furnace chamber 311 and heats it, causing it to melt. The molten metal 301 flows from the pressure port of the pump 331 through the connecting opening 314 in the second furnace chamber 311, flows around the molten metal 350, and then through the connecting opening 313. In the first furnace chamber 310, it flows around the immersion heating elements 331 and then to the suction port of the pump 321.

[0178] Alternatively or additionally to a pump 321, the circulation device 320 can include a stirrer for circulating the molten metal 301. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 301 can be set into rotational motion.

[0179] The exemplary embodiment of the Figure 3The furnace may additionally have a second heating device (not shown). In particular, the second heating device may be arranged in the area of ​​the second furnace chamber 311. The second heating device may, in particular, be an electric heating device. In particular, the second heating device may be arranged in an area that does not come into contact with the melt. In particular, the second heating device may be arranged above the melt. The second heating device may comprise second heating elements in the form of heating rods, heating plates, heating panels, or heating coils. Additionally or alternatively, the second heating device may comprise heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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, thus heating the molten material below the second heating elements.

[0180] Figure 4 This shows a schematic representation of a 400 mm melting furnace for melting metal. Figure 4 The melting furnace 400 is shown in a horizontal section through the melting furnace 400 in a top view.

[0181] The 400 melting furnace is particularly suitable for melting metals with a melting point below 900 °C. The 400 melting furnace is particularly suitable for melting both 450 material, for example in the form of metal shavings, and lumpy 450' material, for example the size of a car wheel rim.

[0182] 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 fluidically connected to each other via a first connecting opening 413 and a second connecting opening 414.

[0183] The melting furnace 400 has a first charging opening 440. The charging opening 440 is designed for supplying metal to be melted, in particular molten material 450, in this case, for example, metal shavings. The charging opening 440 is arranged on the furnace chamber 411 such that the molten material 450 can be introduced from the environment 1 surrounding the melting furnace 400 through the charging opening 440 into the second furnace chamber 411 when the charging opening 440 is open. The charging opening 440 has a width of 40 cm and a height of 40 cm. The charging opening 440 can be closed by a charging door 441. The first charging opening 440 is located at a first end of the second furnace chamber 411 in the area of ​​the second connecting opening 414.

[0184] The melting furnace 400 has a second charging opening 440'. The charging opening 440' is designed for supplying metal to be melted, in particular material 450', in this case, for example, a car wheel rim. The charging opening 440' is arranged on the furnace chamber 411 such that the material 450' can be introduced from the surrounding environment 1 of the melting furnace 400 into the second furnace chamber 411 through the charging opening 440' when the charging opening 440' is open. The charging opening 440' has a width of 60 cm and a height of 60 cm. The charging opening 440' can be closed by a charging door 441'. The second charging opening 440' is located at a second end of the second furnace chamber 411 in the area of ​​the first connecting opening 413.An interior furnace chamber, comprising the furnace chamber 410 and the second furnace chamber 411, can be closed off from the surrounding environment 1 around the melting furnace 400 by the charging opening doors 440 and 440'.

[0185] In particular, areas of the melting furnace 400 designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 410 and furnace chamber 411 are, at least partially, lined with refractory material. The refractory-lined areas 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, molten metal in the melting furnace, especially in 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.

[0186] The melting furnace 400 is electrically heated. The melting furnace 400 comprises a first heating unit 430 with electrically heated immersion heating elements 431, which are 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.

[0187] Furnace chambers 410 and 411 are at least partially filled with molten metal 401, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 411 contains approximately 20% of the molten metal 401 located in furnace 400. Furnace chamber 410 contains approximately 80% of the molten metal 401 located in furnace 400. The molten metal 401 has a temperature of approximately 750 °C.

[0188] The melting furnace 400 comprises a circulation device 420, which is configured to generate a flow of molten metal, 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.

[0189] 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 located in the first furnace chamber 410. A pressure port of the pump 421 is sealed to the second connecting opening 414 such that molten metal 401 flowing through the second connecting opening first flows through the pump 421. A suction port of the pump 421 is located facing the immersion heating elements 431. The second connecting 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 through the second connecting opening 414 into the second furnace chamber 411. As the molten metal 401 flows around the immersion heating elements 431, it 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.

[0190] 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 only one or two rows of immersion heating elements 431, can be provided. The immersion heating elements 431 of a first row can be 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 line with the immersion heating elements 431 of a second row. This is shown schematically in Figure 4 As shown. Some immersion heating elements 431 can also be aligned downstream with each other, and some other immersion heating elements 431 can be arranged offset downstream from each other.

[0191] When the molten metal 450 is introduced into the furnace chamber 411 via the charging opening 440, it is located in the furnace chamber 411. With the pump 421 switched on, the molten metal 401 flows around the molten metal 450 in the furnace chamber 411 and heats it, causing it to melt. The molten metal 401 flows from the discharge port of the pump 431 through the connecting opening 414 in the second furnace chamber 411, first flowing around the molten metal 450, then around the molten metal 450', and through the connecting opening 413. In the first furnace chamber 410, it flows around the immersion heating elements 431 and then to the suction port of the pump 421. The first charging opening 440 is located closer to the discharge port of the pump 421 than the second charging opening 440'.This means that the molten material 450 is first surrounded by the flow and partially melted, before the molten metal 401, now partially encompassing the molten material 450, flows around the molten material 450' and melts it at least partially.

[0192] Alternatively or additionally to a pump 421, the circulation device 420 can include a stirrer for circulating the molten metal 401. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 401 can be set into rotational motion.

[0193] The exemplary embodiment of the Figure 4The furnace may additionally have a second heating device (not shown). In particular, the second heating device may be arranged in the area of ​​the second furnace chamber 411. The second heating device may, in particular, be an electric heating device. In particular, the second heating device may be arranged in an area that does not come into contact with the melt. In particular, the second heating device may be arranged above the melt. The second heating device may comprise second heating elements in the form of heating rods, heating plates, heating panels, or heating coils. Additionally or alternatively, the second heating device may comprise heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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, thus heating the molten material below the second heating elements.

[0194] Figure 5 This shows a schematic representation of a 500 mm melting furnace for melting metal. Figure 5 The melting furnace 500 is shown in a horizontal section through the melting furnace 500 in a top view.

[0195] The 500 melting furnace is particularly suitable for melting metals with a melting point below 900 °C. The 500 melting furnace is especially suitable for melting lumpy materials (melt material 550), for example, the size of a car wheel rim. Furthermore, the 500 melting furnace is suitable for simultaneously loading and melting several larger metal parts.

[0196] 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 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.

[0197] The melting furnace 500 has a first charging opening 540. The charging opening 540 is designed for feeding metal to be melted, in particular material 550, in this case, for example, a car wheel rim. The charging opening 540 is arranged on the furnace chamber 511 such that the material 550 can be introduced from the surrounding environment 1 of 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 60 cm and a height of 60 cm. For example, a conveying device or a robot can be connected to the charging opening so that material can be automatically introduced into the melting furnace 500. The charging opening 540 can be closed by a charging door 541.An interior furnace chamber, comprising the furnace chamber 510 and the second furnace chamber 511, can be closed off from the environment 1 surrounding the melting furnace by the charging opening door 541.

[0198] The melting furnace 500 has a second charging opening 540'. The charging opening 540' is designed for supplying metal to be melted, in particular molten metal 550', in this case, for example, a large number of metal ingots. The charging opening 540' is arranged on the furnace chamber 511 such that the molten metal 550' can be introduced from the surrounding environment 1 of the melting furnace 500 into the second furnace chamber 511 through the charging opening 540' 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 molten metal can be introduced into the second furnace chamber simultaneously. For example, the molten metal can be tipped from a collection container through the charging opening 540'. The melt material 550' could, for example, be remnants from a casting process.The melting furnace can have receiving devices on an outer wall for such a collection container. For example, a conveying device or a robot can be connected to the charging opening so that the charge material can be automatically introduced into the melting furnace 500. The charging opening 540' can be closed by a charging door 541'. An interior furnace chamber, comprising the furnace chamber 510 and the second furnace chamber 511, can be closed off from the environment 1 surrounding the melting furnace by the charging door 541'.

[0199] In particular, areas of the melting furnace 500 designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 510 and furnace chamber 511 are lined with refractory material, at least in part. The refractory-lined areas 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 areas 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, molten metal 501 located in the melting furnace 500, in particular in 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.

[0200] The melting furnace 500 is electrically heated. The melting furnace 500 comprises a first heating device 530 with electrically heated immersion heating elements 531, which are 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.

[0201] Furnace chambers 510 and 511 are at least partially filled with molten metal 501, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 511 contains approximately 20% of the molten metal 501 located in furnace 500. Furnace chamber 510 contains approximately 80% of the molten metal 501 located in furnace 500. The molten metal 501 has a temperature of approximately 750 °C.

[0202] The melting furnace 500 comprises a circulation device 520, which is configured to generate a flow of molten metal, at least partially represented by the arrows 501', within the melting furnace 500. The circulation device 520 includes a pump 521 for conveying the molten metal 501.

[0203] 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 located in the first furnace chamber 510. A pressure port of the pump 521 is sealed to the second connecting opening 514 such that molten metal 501 flowing through the second connecting opening first flows through the pump 521. A suction port of the pump 521 faces the immersion heating elements 531. The second connecting 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 through the second connecting opening 514 into the second furnace chamber 511. 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 described furnace chambers.

[0204] 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 only one or two rows of immersion heating elements 531, can be provided. The immersion heating elements 531 of a first row can be offset from the immersion heating elements 531 of a second row. Alternatively, the immersion heating elements 531 of a first row can be arranged one behind the other or in line with the immersion heating elements 531 of a second row. This is shown schematically in Figure 5 As shown. Some immersion heating elements 531 can also be arranged in a downward alignment with each other, and some other immersion heating elements 531 can be arranged offset from each other downwards.

[0205] When the molten metal 550 is introduced into the furnace chamber 511 via the charging opening 540, it is located in the furnace chamber 511. With the pump 521 switched on, the molten metal 501 flows around the molten metal 550 in the furnace chamber 511 and heats it, causing it to melt. The molten metal 501 flows from the pressure port of the pump 531 through the connecting opening 514 in the second furnace chamber 511, first flowing around the molten metal 550 and then around the molten metal 550', and then through the connecting opening 513. In the first furnace chamber 510, it flows around the immersion heating elements 531 and then to the suction port of the pump 521.

[0206] Alternatively or additionally to a pump 521, the circulation device 520 can include a stirrer for circulating the molten metal 501. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 501 can be set into rotational motion.

[0207] The exemplary embodiment of the Figure 5The furnace may additionally have a second heating device (not shown). In particular, the second heating device may be arranged in the area of ​​the second furnace chamber 511. The second heating device may, in particular, be an electric heating device. In particular, the second heating device may be arranged in an area that does not come into contact with the melt. In particular, the second heating device may be arranged above the melt. The second heating device may comprise second heating elements in the form of heating rods, heating plates, heating panels, or heating coils. Additionally or alternatively, the second heating device may comprise heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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, thus heating the molten material below the second heating elements.

[0208] Figure 6 This shows a schematic representation of a 600 mm melting furnace for melting metal. Figure 6 The melting furnace 600 is shown in a horizontal section through the melting furnace 600 in a top view.

[0209] The 600 melting furnace is particularly suitable for melting metals with a melting point below 1600 °C.

[0210] 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 fluidically connected to each other via a first connecting opening 613 and a second connecting opening 614.

[0211] The melting furnace 600 has a first charging opening 640. The charging opening 640 is designed for supplying metal to be melted. The charging opening 640 is arranged on the furnace chamber 611 such that metal to be melted can be introduced from the environment 1 surrounding the melting furnace 600 into the second furnace chamber 611 through the charging opening 640 when the charging opening 640 is open. The charging opening 640 has a width of 120 cm and a height of 120 cm. The charging opening 640 can be closed by a charging door 641. An interior furnace space, comprising the furnace chamber 610 and the second furnace chamber 611, can be closed off from the environment 1 surrounding the melting furnace by the charging door 640.

[0212] In particular, areas of the melting furnace 600 that are designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 610 and furnace chamber 611 are, at least partially, lined with refractory material. The refractory-lined areas 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 areas 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, molten metal in the melting furnace, in particular in 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 600 is electrically heated. The melting furnace 600 comprises a first heating unit 630 with electrically heated immersion heating elements 631, which are 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.

[0214] Furnace chambers 610 and 611 are at least partially filled with molten metal 601, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 611 contains approximately 60% of the molten metal 601 located in the melting furnace 600. Furnace chamber 610 contains approximately 40% of the molten metal 601 located in the melting furnace 600. The molten metal 601 has a temperature of approximately 750 °C.

[0215] The melting furnace 600 comprises a circulation device 620, which is configured to generate a flow of molten metal, 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.

[0216] 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 located in the first furnace chamber 610. A suction port of the pump 621 is sealed to the first connecting opening such that molten metal 601 flowing through the first connecting opening flows into the pump 621. A discharge port of the pump 621 faces the immersion heating elements 631. The second connecting opening is located downstream of the immersion heating elements 631, so that the molten metal 601, conveyed by the pump, flows through the first furnace chamber, passing around the immersion heating elements 631, and then flows through the second connecting opening 614 into the second furnace chamber 611. Thus, it is evident 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 described furnace chambers.

[0217] 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. The immersion heating elements 631 of a first row can be arranged directly below immersion heating elements 631 of a second row (analogous to the arrangement of the immersion heating elements 231 and as already described above in relation to Figure 2' described). 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 in relation to Figure 2 "described).

[0218] When the molten metal 650 is introduced into the furnace chamber 611 via the charging opening 640, it is located in the furnace chamber 611. With the pump 621 switched on, the molten metal 601 flows around the molten metal 650 in the furnace chamber 611 and heats it, causing it to melt. The molten metal 601 flows from the pump 631, driven by a pressure nozzle of the pump, through the first furnace chamber 610, around the immersion heating elements 631, through the connecting opening 614 into the second furnace chamber 611, around the molten metal 650, and flows to the suction nozzle of the pump 621, which is connected to the connecting opening 613.

[0219] Alternatively or additionally to a pump 621, the circulation device 620 can include a stirrer for circulating the molten metal. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 601 can be set into a rotational motion.

[0220] A second heating device 660 is arranged in the area of ​​the second furnace chamber 611. The second heating device can, in particular, be an electric heating device. Specifically, the second heating device can be arranged in an area within the furnace chamber 611 that does not come into contact with the molten metal. In particular, the second heating device can be arranged above the molten metal. Figure 6In the illustrated embodiment, 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 area of ​​the second heating chamber 611 is heated.

[0221] Figure 6' corresponds to Figure 6 , wherein gas burners are provided as the second heating element 661 instead of heating rods. Only one gas burner is shown as an example. However, one or more gas burners can be provided. The underlying melt 601 can be heated via the gas burner. Figure 6 " corresponds to the Figure 6 , in addition to heating rods, gas burners are also provided as second heating elements 661.

[0222] The gas burner can be positioned closer to the charging opening 640 than the heating elements. This allows heat to be transferred from the gas flame to the area near the charging opening where the material to be melted is located immediately after being fed in. This accelerates the melting process. However, the reverse arrangement (heating elements closer to the charging opening 640 than the gas burner) is also possible.

[0223] Figure 7 shows a schematic representation of a 700 mm melting furnace for melting metal. Figure 7 The melting furnace 700 is shown in a horizontal section through the melting furnace 700 in a top view.

[0224] The 700 melting furnace is particularly suitable for melting metals with a melting point below 900 °C. The 700 melting furnace is especially suitable for melting lumpy material (melt material 750), for example, the size of a car wheel rim. Furthermore, the 700 melting furnace is suitable for simultaneously loading and melting several larger metal parts.

[0225] 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 710 and the second furnace chamber 711 are fluidically connected to each other via a first connecting opening 713 and a second connecting opening 714.

[0226] The melting furnace 700 has a first charging opening 740. The charging opening 740 is designed for feeding metal to be melted, in particular material 750, in this case, for example, a car wheel rim. The charging opening 740 is arranged on the furnace chamber 711 such that the material 750 can be introduced from the surrounding environment 1 of the melting furnace 700 into the second furnace chamber 711 through the charging opening 740 when the charging opening 740 is open. The charging opening 740 has a width of 120 cm and a height of 120 cm. For example, a conveying device or a robot can be connected to the charging opening so that material can be automatically introduced into the melting furnace 700. The charging opening 740 can be closed by a charging door 741.An interior furnace chamber, comprising the furnace chamber 710 and the second furnace chamber 711, can be closed off from the environment 1 surrounding the melting furnace by the charging opening door 740.

[0227] The melting furnace 700 has a second charging opening 740'. The charging opening 740' is designed for supplying metal to be melted, in particular molten metal 750', in this case, for example, a large number of metal ingots. The charging opening 740' is arranged on the furnace chamber 711 such that the molten metal 750' can be introduced from the surrounding environment 1 of the melting furnace 700 into the second furnace chamber 711 through the charging opening 740' 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 molten metal can be introduced into the second furnace chamber simultaneously. For example, the molten metal can be tipped from a collection container through the charging opening 740'. The melt material 750' can, for example, be residue from a casting process.The melting furnace can have receiving devices on an outer wall for such a collection container. For example, a conveying device or a robot can be connected to the charging opening so that the charge material can be automatically introduced into the melting furnace 700. The charging opening 740' can be closed by a charging door 741'. An interior furnace chamber, comprising the furnace chamber 710 and the second furnace chamber 711, can be closed off from the environment 1 surrounding the melting furnace by the charging door 741'.

[0228] In particular, areas of the melting furnace 700 designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 710 and furnace chamber 711 are at least partially lined with refractory material. The refractory-lined areas 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 areas 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, molten metal in the melting furnace, in particular in 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.

[0229] The melting furnace 700 is electrically heated. The melting furnace 700 comprises a first heating device 730 with electrically heated immersion heating elements 731, which are 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.

[0230] Furnace chambers 710 and 711 are at least partially filled with molten metal 701, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 711 contains approximately 20% of the molten metal 701 located in furnace 700. Furnace chamber 710 contains approximately 80% of the molten metal 701 located in furnace 700. The molten metal 701 has a temperature of approximately 750 °C.

[0231] The melting furnace 700 comprises a circulation device 720, which is configured to generate a flow of molten metal, at least partially represented by the arrows 701', within the melting furnace 700. The circulation device 720 includes a pump 721 for conveying the molten metal 701.

[0232] 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 located in the first furnace chamber 710. A pressure port of the pump 721 is sealed to the second connecting opening 714 such that molten metal 701 flowing through the second connecting opening first flows through the pump 721. A suction port of the pump 721 faces the immersion heating elements 731. The second connecting 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 through the second connecting opening 714 into the second furnace chamber 711. 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 described furnace chambers.

[0233] As the immersion heating elements 731 flow around them, 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 only one or two rows of immersion heating elements 731, can be provided. The immersion heating elements 731 of a first row can be offset from the immersion heating elements 731 of a second row. Alternatively, the immersion heating elements 731 of a first row can be arranged one behind the other or in line with the immersion heating elements 731 of a second row. This is shown schematically in Figure 7 As shown. Some immersion heating elements 731 can also be aligned downstream with each other, and some other immersion heating elements 731 can be arranged offset downstream from each other.

[0234] The charging opening 740 is located immediately behind the connecting opening 714 in the direction of flow. When the molten metal 750 has been introduced into the furnace chamber 711 via the charging opening 740, the molten metal 750 is located in the furnace chamber 711. With the pump 721 switched on, the molten metal 701 flows around the molten metal 750 located in the furnace chamber 711 and heats it, causing it to melt. The molten metal 701 flows from the pressure port of the pump 731 through the connecting opening 714 into the second furnace chamber and initially flows around the material to be melted 750. The charging opening 740' is located downstream of the connecting opening 714 and downstream of the charging opening 740. After the molten metal 101 has flowed around the material to be melted 750, it then flows around the material 750' that was introduced through the charging opening 740'.As the molten metal 701 flows through the second furnace chamber 711, it first flows around the melt 750 and then around the melt 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 suction nozzle of the pump 721.

[0235] A second heating device 760 is arranged on a ceiling in a ceiling area 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 may include heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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'.

[0236] Alternatively or additionally to a pump 721, the circulation device 720 can include a stirrer for circulating the molten metal 701. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 701 can be set into rotational motion.

[0237] The Figure 8Figure 1 shows a schematic, perspective view of a melting furnace 800, which is partially shown in section to illustrate the furnace interior. The melting furnace 800 can be filled with molten metal. The depicted 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 designated by reference numeral 831 for illustrative purposes, are electric 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 recirculation device 820 is arranged in a furnace chamber 811', which is located upstream of the furnace chamber 811. The recirculation device 820 comprises a pump 821. A pressure nozzle (i.e.The pressure side of pump 821 faces furnace chamber 811, while the suction side of pump 821 faces furnace chamber 810. Pump 821 circulates molten metal located inside the furnace, pumping it from the first furnace chamber into furnace chamber 811' containing pump 821, and from there into the second furnace chamber 811. From there, it flows back into the first furnace chamber 810 via furnace chamber 811‴. Thus, it is evident that the molten metal circulates within the melting furnace 100. The flow path runs through a kind of annular channel, which encompasses all of the furnace chambers described.

[0238] The dimensions of furnace chambers 810, 811, 811', 811", 811‴ are exemplary. In particular, furnace chamber 811 can be smaller. It can only be comparatively large if its charging opening 840 is sufficiently large to accommodate any returned parts (i.e., defective castings that need to be remelted).

[0239] The second furnace chamber 811 has a charging opening 840 for introducing material to be melted. The charging opening 840 is located in the upper half of the vertical height of the second furnace chamber 811. A second charging opening 840' is provided on a furnace chamber 811". The second charging opening 840' is smaller than the first charging opening 840. The first charging opening 840 is suitable for larger metal parts, for example, with a size of at least 40 cm and at most 300 cm, and the second charging opening 840' is suitable for bulk material, for example, metal shavings with a maximum length of, for example, 10 cm and a 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 in the lower recess of the furnace chamber. A second heating device 860 is arranged on the ceiling of 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 also has a dispensing pocket 811' v<, which is arranged on the chamber 811' and fluidically connected to it. Furthermore, a cleaning opening 870 (see...) is provided. Fig. 11 ) provided at the furnace chamber 811. The cleaning opening 870, the loading openings 840 and 840' each have a lid or a door for closing, these are in Figure 8 however, it is not shown.

[0240] Figure 9 shows the melting furnace 800 of the Figure 8 in a section along a through the in Figure 8The plane defined by the drawn lines A and B.

[0241] Recurring features in the figures are labelled with the same reference symbols.

[0242] In Figure 9 The furnace chamber 811, the furnace chamber 811'', the furnace chamber 810, and the furnace chamber 811'' are shown in section. In furnace chamber 811, the heating elements 861, arranged on the ceiling of furnace chamber 811, are visible in the form of heating rods. The pump 821 conveys molten metal through the furnace chambers in the direction indicated by the arrow 801'. The molten metal is pumped by the pump 821 into the second furnace chamber 811 through an inlet opening 814. Figure 10 is an excerpt of Figure 8Figure 9 is shown enlarged again to illustrate furnace chamber 811‴. Furnace chamber 811‴, i.e., the impurity collection chamber, includes a lowered area in the form of a floor depression 8112. A floor 8113 of an inlet area of ​​furnace chamber 811‴ is at the same level as a floor 8114 of furnace chamber 811 in the outlet area of ​​furnace chamber 811. Behind the inlet area of ​​furnace chamber 811‴, a depression 8112 is formed in furnace chamber 811‴. Sediments can enter furnace chamber 811‴ from furnace chamber 811 and are deposited in the depression 8112. A bottom 8115 of an outlet opening of the furnace chamber 811‴ is arranged above a bottom of the depression 8112, so that the sediments cannot enter the downstream furnace chamber 810, or can only enter partially. The bottom of the furnace chamber 810 is at the same level as the bottom 8115 of the outlet opening of the furnace chamber 811''.

[0243] In Figure 10An optional maximum fill level kmax and an optional minimum fill level kmin are shown. These fill levels represent the minimum and maximum possible fill heights of molten metal that ensure proper furnace operation. If furnace chamber 811 is heated electrically rather than with burners that produce exhaust gases, the opening for the melt into furnace chamber 811‴ can end above the maximum fill level kmax of the melt in the furnace, as 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. During the furnace's melting process, these impurities are continuously transported from the first chamber into furnace chamber 811‴ by the melt circulation; this also applies to the sediments in the first chamber.A weir in the outflow area of ​​furnace chamber 811 retains impurities on the molten metal surface, allowing them to be skimmed off. Sediments are retained by the depression 8112 in the bottom. An outlet valve (not shown) is located at the lowest point of the depression 8112. A conveying direction for the molten metal is shown in [reference missing]. Figure 10 indicated again by the arrow 801'.

[0244] Figure 11 shows a section through furnace chamber 811 in a vertical direction along the in Figure 8The charging opening 840 is clearly visible on the line C shown. A charging door (not shown) is arranged at the charging opening 840 for closing it. The cleaning opening 870 is closed by a cleaning door 870'. The arrows 801' schematically indicate the flow of the molten metal from the inlet opening 814 towards the outlet opening 813. An outer wall of the furnace chamber 811, on which the charging opening 840 is formed, can be designed as an inclined plane (also called a cleaning ramp) 8401 (as in Fig. 11 shown).

[0245] Figure 12 shows an alternative design of furnace chamber 811 of melting furnace 800. Figure 8 - 11At the feed opening 840, a feed ramp 8402 can be provided in addition to or as an alternative to the cleaning ramp 8401. The feed ramp 8402 is arranged, in particular, above a molten metal level k. This allows metal parts to dry on the feed ramp 8402. One or more gas burners 862 can be arranged above the feed ramp 8402 for heating the metal placed on the feed ramp 8402, as for example in Figure 13 shown.

[0246] A gas circulation device 880 can be additionally or alternatively provided in the furnace chamber 811. This is shown in Fig. 14The gas recirculation device 880 can include a blower 881. This blower can be designed and arranged such that furnace atmosphere is extracted from a first region of the furnace chamber 811 and blown back in at the charging ramp 8402. In particular, air heated by the heating elements 861 can be blown back into the furnace interior at the charging ramp 8402, especially above the charging ramp. The arrows 802' indicate a gas circulation direction of the gas recirculation device 880.

[0247] Figure 15 shows a cross-section through the second furnace chamber of the melting furnace of the Figures 8 to 14 , where gas burners 861' are provided instead of electric heating elements.

[0248] Figure 16 shows a schematic representation of a 1500-era melting furnace for melting metal. Figure 16The melting furnace 1500 is shown in a horizontal section through the melting furnace 1500 in a top view.

[0249] The 1500 melting furnace is particularly suitable for melting metals with a melting point below 1200 °C. The 1500 melting furnace is also particularly suitable for melting lumpy materials (melt material 1550), for example, the size of a car wheel rim. Furthermore, the 1500 melting furnace is suitable for simultaneously loading and melting several larger metal parts.

[0250] 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 such that it forms an interior space 15121. The first furnace chamber 1510 and the second furnace chamber 1511 are fluidically connected to each other via a first connecting opening 1513 and a second connecting opening 1514.

[0251] The melting furnace 1500 has a first charging opening 1540. The charging opening 1540 is designed for feeding metal to be melted, in particular material 1550, in this case, for example, a car wheel rim. The charging opening 1540 is arranged on the furnace chamber 1511 such that the material 1550 can be introduced from the surrounding environment 1 of the melting furnace 1500 into the second furnace chamber 1511 through the charging opening 1540 when the charging opening 1540 is open. The charging opening 1540 has a width of 60 cm and a height of 60 cm. For example, a conveying device or a robot can be connected to the charging opening so that the material can be automatically introduced into the melting furnace 1500. The loading opening 1540 can be closed by a loading opening door 1541.An interior furnace space, comprising the furnace chamber 1510, can be closed off from the surrounding environment 1 by the charging opening door 1541.

[0252] The loading opening 1540 and / or 1540' and / or 1540" for the loading parts can be arranged vertically or almost vertically. That is, an angle between the vertical and the plane of the loading opening can be, in particular, less than 45°, preferably less than 25° and / or equal to 0° or greater than 0°.

[0253] The feed opening 1540 and / or 1540' and / or 1540" can be arranged horizontally or almost horizontally, so that the feed parts are introduced into the melt from above. This means that the angle between the horizontal and the plane of the feed opening can be, in particular, less than 45°, preferably less than 25° and / or equal to or greater than 0°. The cover of the feed opening can then be a lid that pivots upwards to expose the corresponding feed opening 1540 and / or 1540' and / or 1540". One or more of the feed openings can be arranged horizontally as described above, and one or more feed openings can be arranged vertically as described above.

[0254] For feeding a collection of charge parts, which are, for example, pushed or tipped from a charge container into the melt, the width of the charge chamber can be greater than the width of the inlet or outlet opening of the corresponding furnace chamber. This is in Figure 16 The loading chamber 1511 is shown as an example at the loading opening 1540'.

[0255] The melting furnace 1500 has a second charging opening 1540'. The charging opening 1540' is designed for supplying metal to be melted, in particular molten metal 1550', in this case, for example, a large number of metal ingots. The charging opening 1540' is arranged on the furnace chamber 1511 such that the molten metal 1550' can be introduced from the surrounding environment 1 of the melting furnace 1500 into the second furnace chamber 1511 through the charging opening 1540' 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 molten metal 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 1 540'. The melt material 1550' may, for example, be in the form of returns from a casting process.The melting furnace 1500 can have receiving devices on an outer wall for such a collection container. For example, a conveying device or a robot can be connected to the charging opening so that the charge material can be automatically introduced into the melting furnace 1500. The charging opening 1540' can be closed by a charging door 1541'. An interior furnace chamber, comprising the furnace chamber 1510 and the second furnace chamber 1511, can be closed off from the surrounding environment 1 of the melting furnace 1500 by the charging door 1541'.

[0256] The melting furnace 1500 has a third charging opening 1540". The charging opening 1540 is designed for supplying metal to be melted, in particular molten metal 1550, in this case, for example, metal shavings. The charging opening 1540 is arranged on the furnace chamber 1511 such that the molten metal 1550 can be introduced from the surrounding environment 1 of the melting furnace 1500 into the second furnace chamber 1511 through the charging opening 1540 when the charging opening 1540 is open. The molten metal 1550 can, for example, be in the form of metal shavings. The charging opening 1540 can be closed by a charging door 1541. An interior furnace chamber, comprising the furnace chamber 1510 and the second furnace chamber 1511, can optionally be closed off from the environment 1 surrounding the melting furnace 1500 by means of the charging opening door 1541".It should be noted that, particularly due to the areas a with reduced flow cross-section in front of and behind the feed opening 1540", a feed opening door is not mandatory.

[0257] In particular, areas of the melting furnace 1500 designed to come into contact with molten metal are lined with refractory material. For example, furnace chamber 1510 and furnace chamber 1511 are, at least partially, lined with refractory material. The refractory-lined areas 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 areas 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, molten metal 1501 located in the melting furnace 500, in particular in furnace chambers 1510 and 1511, 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.

[0258] In the dark marked areas a, the flow cross-section is reduced, with feed openings being located upstream of these areas.

[0259] The melting furnace 1500 is electrically heated. The melting furnace 1500 comprises a first heating device 1530 with electrically heated immersion heating elements 1531, which are 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. The immersion heating elements 1531 have a refractory surface and can be immersed in molten metal to heat it.

[0260] Furnace chambers 1510 and 1511 are at least partially filled with molten metal 1501, for example, molten aluminum. The molten aluminum consists of aluminum. The molten aluminum can, for example, be an aluminum alloy. Furnace chamber 1511 contains approximately 80% of the molten metal 1501 that is located in furnace 1500. Furnace chamber 1510 contains approximately 20% of the molten metal 1501 that is located in furnace 1500. The molten metal 1501 has a temperature of approximately 750 °C.

[0261] The melting furnace 1500 comprises a first circulation device 1520, which is configured to generate a flow of molten metal, at least partially represented by arrows 1501', within the melting furnace 1500. The circulation device 1520 includes 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 flow of molten metal, at least partially represented by arrows 1501', within the melting furnace 1500. The circulation device 1520' includes a pump 1521' for conveying the molten metal 1501.

[0262] 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 located in the first furnace chamber 1510. A pressure port of the pump 1521 is sealed to the second connecting opening 1514 such that molten metal 1501 flowing through the second connecting opening 1514 first flows through the pump 1521. A suction port of the pump 1521 faces the immersion heating elements 1531. The second connecting 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 through the second connecting opening 1514 into the second furnace chamber 1511. Thus, it is evident 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 described furnace chambers.

[0263] As the immersion heating elements 1531 flow around them, 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 only one or two rows of immersion heating elements 1531, can be provided. The immersion heating elements 1531 of a first row can be 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 line with the immersion heating elements 1531 of a second row. Some immersion heating elements 1531 can also be aligned downstream with each other, and some other immersion heating elements 1531 can be offset from each other downstream. The second circulation device 1520', in particular the second pump 1521', is arranged downstream behind the first circulation device.The second pump 1521' is arranged in particular between the feed opening 1540" and the feed opening 1540'.

[0264] The first recirculation unit 1520' increases the pressure of the melt to compensate, for example, for the pressure loss in specially shaped flow channels or flow elements, which are necessary, for example, for the immersion melting of metal chips. The second recirculation unit 1520' is optional. The melting furnace 1500 can also be configured without the second recirculation unit. The melting furnace can include special flow channels to increase or decrease the pressure of the melt.

[0265] 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 can be designed in accordance with the furnace chamber 811‴ described in relation to the melting furnace 800. The contaminant collection chamber can have a closable opening for removing contaminants.

[0266] When the molten material 1550 has been introduced into the furnace chamber 1511 via the charging opening 1540", the molten material 1550 is located in the furnace chamber 1511. With the pump 1521 switched on, the molten metal 1501 flows around the molten material 1550 located in the furnace chamber 1511 and heats it, causing it to melt. The molten metal 1501 flows from the pressure port of the pump 1521 through the connecting opening 1514, through the second furnace chamber 1511, first flowing around the melt 1550" and then around the melt 1550' and then around the melt 1550 and flows through the connecting opening 1513, flows around the immersion heating elements 1531 in the first furnace chamber 1510 and flows to the suction port of the pump 1521. Between the charging opening 1540" and 1540', the pump 1521' can be arranged such that a pressure port points towards the charging opening 1540' and a suction port points towards the charging opening 1540'.

[0267] Alternatively or additionally to a pump 1521, the circulation device 1520 can include a stirrer for circulating the molten metal 1501. The stirrer can, for example, be located outside the furnace chambers and can be electromagnetic. Alternatively, the stirrer can be located below the furnace chambers. By applying an alternating electromagnetic field, the molten metal 1501 can be set into rotational motion.

[0268] The exemplary embodiment of the Figure 16The furnace may additionally have a second heating device (not shown). In particular, the second heating device may be arranged in the area of ​​the second furnace chamber 1511. The second heating device may, in particular, be an electric heating device. In particular, the second heating device may be arranged in an area that does not come into contact with the melt. In particular, the second heating device may be arranged above the melt. The second heating device may comprise second heating elements in the form of heating rods. Additionally or alternatively, the second heating device may comprise heating elements in the form of gas burners. The heating elements may be arranged under a ceiling of a furnace chamber, in particular 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.

[0269] It should be noted that features disclosed with respect to one embodiment can be combined with another embodiment, even if this is not explicitly described in the description of the corresponding embodiment.

[0270] Figure 17 Figure 1 shows a sectional view of a melting furnace 1700 for melting metal according to a further embodiment. The section plane runs horizontally in space and, for example, at approximately half the vertical height of the melting furnace 1700. The melting furnace 1700 has a furnace housing 1703 that surrounds an annular melting channel 1710. More precisely, the melting furnace 1700 has refractory-lined walls 1701 located within the furnace housing 1703. The refractory side walls 1701 and the floor shown form the annular melting channel 1710, which is enclosed (i.e., surrounded) by the furnace housing 1703.

[0271] The annular channel 1710 is rectangular in shape. A flow of molten metal circulates within the annular channel 1710. Example flow arrows 1702 indicate a flow direction, which can also be reversed. The flow arrows 1702 also indicate a perforation in an intermediate wall within the annular channel 1710 located outside the plane of the section, by means of which the annular channel 1710 assumes a continuous or closed ring shape.

[0272] The annular channel 1710 (and the furnace housing 1703) surrounds an inner chamber 1752 of the melting furnace 1700. This inner chamber 1752 is preferably free of furnace components, with the exception of any components permanently attached to the furnace housing 1701. The inner chamber 1752 is generally accessible for maintenance work and is sufficiently large to allow maintenance personnel to work there.

[0273] 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.

[0274] The annular channel 1710 also includes heating devices 1730, each with, 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 shadows of the respective other immersion heating elements 1731.

[0275] The annular channel 1710 also includes a feed opening, not shown separately, which is positioned directly above a feed material melting area 1750.

[0276] The annular channel 1710 has several straight sections 1712, which are angled to adjacent straight sections 1712, here by approximately 90° as an example. The straight sections 1712 are connected to each other via deflection sections 1714. An inner wall 1711 of the annular channel 1710 is rounded or chamfered in the area of ​​the deflection sections 1714, as explained in more detail below.

[0277] A bottom weir 1740 is positioned in or adjacent to at least some of the deflection zones 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 zones 1714. This reduces the free wall surface on the inner wall 1711 in the region of the deflection zones 1714 where the molten metal could come into contact. 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 as a result of potentially solidifying molten metal on non-straight wall sections of the annular channel 1710.

[0278] To allow the molten metal to flow completely 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. Although contraction of the solidifying molten metal can also lead to increased stresses at these connecting channels 1742, any damage to the bottom weirs 1740 is less significant than at the deflection area 1714 (and more precisely, than at the corners of the inner walls within the deflection areas 1714). Furthermore, the stresses at the bottom weirs 1740 can be relieved by plastic deformation of the metal because the amount of metal in the connecting channels 1742 is less than at the aforementioned corners.

[0279] In Figure 17The corners 1715 of some of the deflection areas 1714 are marked, and these corners 1715 are chamfered to further reduce stress peaks in a solidifying molten metal. For example, only the inner corners 1715 of the inner wall 1711 and / or near the inner area 1752 are chamfered accordingly, as higher stresses occur there. A further advantage of the chamfered inner corners 1715 is a reduction in flow dead zones downstream of the corners 1715 and a reduction in flow separation in the area of ​​the corners 1715.

[0280] Figure 18 shows a subdivision of the melting furnace from 1700 Fig. 17into individual modules numbered 1-12. Modules 1-12 are arranged in a line along a flow direction through the annular channel 1710. Each module 1-12 is connected to the preceding and subsequent modules 1-12 in the flow direction in a molten-conducting manner and is fluid-tight 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. Specifically, the following modules are provided: Number 1: Module with a recirculating pump; Number 2: Module with a vertical charging opening, i.e.,which in particular allows a metal feed along an at least approximately horizontal axis, since the feed opening itself lies in a vertical plane; Number 3: Module with opening for skimming the melt surface (comparable to or comprising an impurity collection chamber disclosed herein); Numbers 4, 5, 6, 8, 9, 10: Modules with immersion heating elements; Number 7: Module with horizontal feed opening, i.e., which in particular allows a metal feed along an at least approximately vertical axis, since the feed opening itself lies in a horizontal plane; Number 11: Corner module; Number 12: Module for molten metal extraction.

[0281] Fig. 19Figure 1 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 open on one side, e.g., with respect to their outer outline in the top view shown. On one of their longitudinal sides, and in particular at both ends thereof, each module 1, 2 has connection areas 2000 for a fluid-tight and mechanical connection with the other module 1, 2. The connection areas 2000 each include an opening through which molten metal can be exchanged with the corresponding other module 1, 2. Depending on the flow direction, this opening functions as an inlet or outlet. The connection areas 2000 also each include flange areas 210, which serve as interfaces for connecting the connection areas 2000 to one another. The flange areas 2010 can, for example,A furnace housing, each encompassed by modules 1 and 2, is surrounded by a ring-shaped structure near the connection areas 2000.

[0282] It can be seen again that modules 1 and 2 define an annular channel 2012 that surrounds an unobstructed inner area 2014. Furthermore, one of the modules 1 includes a circulation device 2016, and both modules 1 and 2 include, by way of example, immersion heating elements 2018. The position of a metal feed via a feed opening (not shown separately) is indicated by an arrow 2020. The position of a melt withdrawal via a tapping opening (not shown separately), melt withdrawal pump, or other device is indicated by an arrow 2022.

[0283] Dividing the melting furnace into two modules, 1 and 2, facilitates transport to the installation site. In particular, a top view of... Fig. 19The vertical width dimension of the individual modules 1, 2 is significantly reduced compared to the melting furnace composed of them.

[0284] Fig. 20 Figure 1 shows an alternative configuration of a melting furnace 100 according to a further embodiment, wherein the melting furnace 100 is composed of exactly four modules 1-4. Two of the modules 1 and 2 are similar to the variant shown in Figure 2. Fig. 19 They are formed, but not directly connected to each other. Instead, they are indirectly connected to each other via further modules 3 and 4, with each of the further modules 3 and 4 shown in the top view as... Fig. 20a section of a vertically extending transverse side of the melting furnace is defined. These further modules 3 and 4, merely as examples, define comparatively shorter sections of the annular channel 2012 and both of the further modules 3 and 4 feature immersion heating elements 2018. The further modules 3 and 4 also each have connection areas 2000 and flange areas 2010 of the type described above.

[0285] 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 applies in particular to the melting capacity due to the additional immersion heating elements 2018 of the additional modules 3 and 4.

[0286] Figure 21 shows a view of a single module 1780 of the melting furnace 1700 from the Figure 17 & 18 , wherein the single module 1780 comprises a lid lifting device 1790. It can first be seen that the single module 1780, like each of the modules 1-12, consists of Fig. 18It comprises an inlet opening 1792 and an outlet opening 1794 facing away from the viewer. Depending on the flow direction, the functional assignment of inflow and outflow between openings 1792 and 1794 can change. Exemplary flow arrows 1702 through the single module 1780 are shown in Fig. 21 registered.

[0287] The single module 1780 includes a cover 1796. The immersion heating element 1731 is attached to this cover as an example, so that the single module 1780 can be connected to, for example, module 4. Fig. 18 The lid 1796 can be lifted, for example, by means of the lid lifting device 1790, either electrically or hydraulically, in a vertical direction. The lid lifting device 1790 is located in the interior area 1752. Fig. 17The immersion heating element 1731, which is raised together with the lid 1796, can, however, be accessed from the outside of the melting furnace 1700. The immersion heating element 1731 is therefore more easily accessible than the lid lifting device 1790, which accommodates its shorter maintenance intervals.

[0288] By arranging the lid lifting device 1790 on one side of the single 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. 1 Furnace area 100 Furnace 101 Molten metal 101 Molten metal flow 110 Furnace chamber 111 Second furnace chamber 120 Circulation device 121 Pump 130 First heating device 131 Immersion heating element 140 First charging opening 141 Charging opening door 200 Melting furnace 201 Metal melt 201'Metal melt flow 210 Furnace chamber 211 Second furnace chamber 212 Furnace wall 212'Partition wall 213 First connecting opening 214 Second connecting opening 220 Circulating device 221 Pump 230 First heating device 231 Immersion heating element 240 First charging opening 241 Charging opening door 250 Melt 300 Melting furnace 301 Metal melt 301'Metal melt flow 310 Furnace chamber 311 Second furnace chamber 312 Furnace wall 312'Partition wall 313 First connecting opening 314 Second connecting opening 320 Circulating device 321 Pump 330 First heating device 331 Immersion heating element 340 First charging opening 341 Charging opening door 350 Melt 400 Melting furnace 401 Melting metal 401' Melting metal flow 410 Furnace chamber 411 Second furnace chamber 412 Furnace wall 412' Partition wall 413 First connecting opening 414 Second connecting opening 420 Circulating device 421 Pump 430 First heating device 431 Immersion heating element 440 First charging opening 440' Second charging opening 441 First charging opening door 441' Second charging opening door 450 Melting material (metal shavings) 450' Melting material (car rim) 500 Melting furnace 501 Melting metal 501' Melting metal flow 510 Furnace chamber 511 Second furnace chamber 512 Furnace wall 512' Partition wall 513 First connecting opening 514 Second connection opening 520 Circulation device 521 Pump 530 First heating device 531 Immersion heating element 540 First loading opening 540' Second loading opening 541 First loading opening door 541' Second loading opening door 550 Melt (car rim) 550' Melt (metal to be melted, e.g., metal ingot) 600 Melting furnace 601 Metal melt 601'Metal melt flow 610 Furnace chamber 611 Second furnace chamber 612 Furnace wall 612'Partition wall 613 First connecting opening 614 Second connecting opening 620 Circulating device 621 Pump 630 First heating device 631 Immersion heating element 640 First charging opening 641 Charging opening door 650 Molten material 660 Second heating device 661 Second heating elements 700 Melting furnace 701 Metal melt 701'Metal melt flow 710 Furnace chamber 711 Second furnace chamber 712 Furnace wall 712'Partition wall 713 First connecting opening 714 Second connecting opening 720 Circulating device 721 Pump 730 First heating device 731 Immersion heating element 740 First charging opening 740' Second charging opening 741 First charging opening door 741' Second charging opening door 750 Melt (car rim) 750' Melt (metal to be melted, e.g., metal ingot) 760 Second heating device 761 Second heating elements 800 Melting furnace 810 Furnace chamber 811 Second furnace chamber 811' Further furnace chamber 811" Further furnace chamber 811‴ Further furnace chamber 811' v< Extraction pocket 8112 Recess 8113 Bottom of furnace chamber inlet area 811"' 8114 Bottom of furnace chamber outlet area 811 8115 Bottom of furnace chamber outlet opening 811"' 813 Outlet opening 814 Inlet opening 820 Circulation device 821 Pump 830 First heating device 831 Immersion heating element 840 First charging opening 8401 Ramp 8402 Charging ramp 840' Second charging opening 860 Second heating device 861 Second heating elements 861' Gas burner 862 Gas burner 870 Cleaning opening 870' Cleaning opening door 880 Gas recirculation device 881 Blower k max Maximum fill level k min Minimum fill level 1500 Melting furnace 1501 Metal melt 1501' Metal melt flow 1510 Furnace chamber 1511 Second furnace chamber 1511' Impurity collection chamber 1512 Furnace wall 1512' Partition wall 15121Interior 1513First connection opening 1514Second connection opening 1520Circulation device 1521Pump 1520'Second circulation device 1521'Second pump 1530First heating device 1531Immersion heating element 1540First loading opening 1540'Second loading opening 1540"Third loading opening 1541First loading opening door 1541'Second loading opening door 1541"Third loading opening door 1550Melt (car rim) 1550'Melt (metal to be melted, e.g., metal ingot) 1550"Melt (metal to be melted, e.g., metal shavings) aAreas of reduced flow cross-section 1700 Melting furnace 1701 Refractory lined side wall of the furnace 1703 Furnace housing 1702 Flow arrow / Flow direction 1710 Annular channel 1711 Inner wall 1712 Straight section 1714 Deflection area 1715 Corner with chamfer 1720 Circulation device 1730 Heating device 1731 Immersion heating element 1740 Bottom weir 1742 Connecting channel 1750 Charge material melting area 1752 Inner area 1754 Channel segment 1780 Single module 1790 Lid lifting device 1792 Inlet opening 1794 Outlet opening 1796 Lid 2000 Connecting area 2010 Flange area 2012 Annular channel 2014 Inner area 2016 Circulation device 2018 Immersion heating elements 2020 Metal feed 2022 Melt extraction 1-12 Module

Claims

1. A melting furnace (100) for melting metal, comprising: - at least one charging opening (140) for supplying metal to be melted; - a first heating device (130) with at least one electrically heatable immersion heating element (131); and - a circulating device (120), which is configured to produce a molten metal flow inside the melting furnace (100), which circulates between the circulating device (120) and the immersion heating element (131) and flows past the charging opening (140), and - a ring channel (1710), which is an annular melt channel for the molten metal flow, wherein: - the heating device (130) and the circulating device (120) are arranged in the ring channel and / or wherein the ring channel (1710) is accessible through the charging opening (140), characterized in that the melting furnace (100) has a free inner area (15121) around which the ring channel (1710) extends, wherein the inner area (1752) has an area of at least 1 m2.

2. The melting furnace (100) according to claim 1, wherein the ring channel (1710) is configured to be circulated by the molten metal flow, in particular as an open trough flow.

3. The melting furnace (100) according to any one of the preceding claims, wherein the inner area (1752) is accessible, in particular for performing maintenance work.

4. The melting furnace (100) according to any one of the preceding claims, wherein the ring channel (1710) comprises a plurality of modules (1-12) through which the molten metal flow flows respectively.

5. The melting furnace (100) according to claim 4, wherein: the modules (1-12) are arranged in succession and / or in a row along a flow direction of the molten metal; and / or the modules (1-12) form parts of the melting furnace that can be handled independently and / or transported independently and / or produced independently; and / or each module (1-12) is supported independently on a ground; and / or each module (1-12) comprises a section of the ring channel which is at least 0.5m long.

6. The melting furnace (100) according to claim 4 or 5, wherein each module (1-12) has at least one inlet opening (1792) and at least one oulet opening (1794).

7. The melting furnace (100) according to any one of the claims 4 to 6, wherein each module (1-12) is connected in a fluid-tight manner to at least two further modules (1-12) for transferring the molten metal flow between the modules (1-12).

8. The melting furnace (100) according to any one of the claims 4 to 7, wherein each module (1-12) comprises a furnace housing, which is lined with a refractory material.

9. The melting furnace (100) according to any one of the claims 4 to 8, wherein the following applies to the dimensions of at least a plurality of 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. The melting furnace (100) according to claim 6, wherein the modules (1-12) have a connecting area at at least one inlet opening (1792) and / or at at least one outlet opening (1794) by means of which they can be connected to any other module (1-12).

11. The melting furnace (100) according to any one of the preceding claims, further comprising at least one second heating device (660) which is positioned or can be positioned 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.

12. The melting furnace (100) according to claim 11, wherein the second heating device (660) is electrically heatable and in particular is designed as a ceiling radiator and / or wherein the second heating device comprises at least one gas burner (861').

13. The melting furnace (100) according to any one of the claims 11 to 12, wherein the second heating device (660) and the first heating device (130, 630) are arranged in different furnace chambers (610, 611, 612, 612').

14. The melting furnace (100) according to any one of the preceding claims, further comprising a lid (1796) and a lid-lifting device (1790), which is configured to lift the lid (1796) for making the ring channel (1710) accessible, in particular wherein the lid (1796) can be lifted substantially vertically and / or in a straight line, and wherein the lid-lifting device (1790) is arranged on a side of the melting furnace (100) facing the inner area (1752).

15. Method for producing a melting furnace (100) with a ring channel (1710), in which a molten metal can be circulated, characterized by: - connecting individual modules (1-12) to form at least one portion of the melting furnace (100) and so that the melting furnace (100) has a free inner area (15121) which the ring channel (1710) extends around, wherein each module (1-12) comprises a channel segment of the ring channel (1710) and an inlet opening (1792) and at least one outlet opening (1794), wherein the inner area (1752) has an area of at least 1 m2.