Aluminum smelting system and process

Abstract

The invention relates to an aluminum waste melting system (1) comprising a melting furnace (10) including a burner (20) which includes an oxidizer injector (23), and a fuel injector (25); a suction hood (30) for capturing combustion fumes (F) by suction and including a carbon monoxide sensor (37) configured to measure a carbon monoxide concentration (C) in said combustion fumes (F); and a control device (50) configured to receive an input information representative of the value of the carbon monoxide concentration (C), and to control the oxidizer injector (23) and / or the fuel injector (25), according to said input information, the oxidizer and fuel flow rates being controlled to keep the level of volatile organic compounds (VOCs) at the outlet of the melting furnace below a safety value.The invention also relates to a method for melting aluminum waste by such a melting system (1). Figure 1.

Description

Title of the invention: Aluminum waste melting system and process. Technical field of the invention

[0001] The present invention relates to the field of aluminum waste recycling and more particularly, to the field of aluminum waste melting systems for melting aluminum waste.

[0002] The present invention also relates to the field of aluminum waste melting processes by an aluminum waste melting system. State of the art

[0003] In the field of aluminum waste recycling, rotary kilns, or tilting rotary kilns, are known to be used. This technology is specifically designed to process oxidized waste, such as foundry dross, or materials containing organic coatings, such as coated coils, manufacturing scrap, or materials made up of small individual particles, such as beverage cans, or UBCs (Used Beverage Cans) according to established Anglo-Saxon terminology. Before being introduced into the rotary kiln, the beverage cans are generally compacted to form a load with an overall parallelepiped or cubic shape. Since beverage cans are coated with varnish and paint, organic residues are systematically found in these loads.The residual carbon content in each batch is therefore highly variable and depends on the amount of varnish and paint present on the crushed beverage cans in the batch and the process control conditions.

[0004] During the melting of aluminum scrap, in addition to the liquid aluminum intended for recovery and casting, oxides, which are impurities present in the molten mass, are also formed. To eliminate these oxides, it is known in the prior art to use salts which, on the one hand, limit the oxidation of the aluminum, and on the other hand, separate these oxides from the molten mass by forming a slag on the surface of the molten metal.

[0005] To remove organic coatings, different methods can be used. A first method as described in document US2017 / 0051914A1 consists of evaporating the organic coatings by heating, then carrying out afterburning in a separate chamber before melting the metal in a second furnace.

[0006] Alternatively, and as described in documents WO2005 / 085732A1 and EP1243663A2, it is possible to remove organic coatings by descaling the beverage cans through combustion directly in the furnace used for smelting the metal. In such an operation, the stoichiometry of the oxidizer and fuel is crucial, as it influences the composition of the combustion fumes produced and the quality of the resulting liquid metal. If the quantity of oxidizer is insufficient, combustion is incomplete and produces volatile organic compounds (VOCs) rather than carbon dioxide.

[0007] Volatile organic compounds (VOCs) refer to all organic molecules containing at least one carbon atom bonded to hydrogen, nitrogen, oxygen, sulfur, chloride, etc., with the exception of carbon monoxide (CO), carbon dioxide (CO2), water (H2O), and nitrogen oxides (NOx). A primary problem with VOC formation is that it contributes to lowering the temperature inside the furnace. A secondary problem arises from the fact that some VOCs are toxic. It is therefore essential to limit their formation or drastically reduce their concentration before venting combustion fumes from the melting system. Furthermore, most industrial processes are subject to regulatory requirements governing VOC emission limits.

[0008] However, if the conditions are highly oxidizing (i.e., with a quantity of oxidant greater than the quantity of fuel), all the organic matter is burned to form carbon dioxide, but it is possible to oxidize the liquid aluminum, and thus generate oxides. One consequence of this oxide generation is that they can be incorporated into the molten metal, which degrades the quality of the metal obtained after solidification. Document WO2005 / 085732A1 therefore provides for a reduction phase of the oxidation of liquid aluminum to prevent the formation of oxides. However, such a reduction phase has the disadvantage of increasing the quantity of fuel released (for example, methane), which is a volatile organic compound.

[0009] It is therefore clear that, given the highly variable carbon content in each charge, it is very difficult to control the maximum amount of charge to be introduced into the furnace to guarantee both optimal combustion and efficient metal melting, while limiting VOC emissions outside the melting system. Furthermore, since the oxidant flow rate is technically limited by the furnace's capacity, it is sometimes impossible to supply enough oxidant to prevent incomplete combustion, particularly if the carbon content in the charge is too high.

[0010] Furthermore, in fusion devices such as those described in document WO2005 / 085732A1, the combustion fumes produced are introduced into a pipes to be cooled. This cooling method generally involves the formation of toxic dioxins which should be prevented. Object of the invention

[0011] The present invention aims to provide a solution that addresses all or part of the aforementioned problems. In particular, the fusion system according to the invention aims to: - limit the formation of VOCs; - limit the formation of dioxin; - to achieve the melting of aluminium and the combustion of organic coatings inside the same furnace, while limiting the formation of oxides; - to achieve the melting of an optimal quantity of aluminum waste in a large furnace.

[0012] This goal can be achieved through the implementation of an aluminum waste melting system to melt aluminum waste, the melting system comprising: - a melting furnace intended for melting said aluminum waste, and comprising: - a drum internally delimiting a melting chamber intended to receive the said aluminum waste to be melted; - a burner comprising an ignition device, at least one oxidizer injector, and at least one fuel injector, said oxidizer injector being configured to inject a flow of oxidizer into the melting chamber, said fuel injector being configured to inject a flow of fuel into the melting chamber, and the ignition device being configured to start combustion of the oxidizer and fuel injected into the melting chamber, to bring heat into the melting chamber; - means of evacuation configured to allow the extraction of all or part of the combustion fumes from inside the melting enclosure to an open air area located outside the melting enclosure and where the air is free to circulate; - an extraction hood located outside the melting enclosure and intended to capture by suction all or part of the said combustion fumes present in the open air zone, said extraction hood further comprising a control line including at least one carbon monoxide sensor configured to measure a value of a carbon monoxide concentration in the said combustion fumes captured by the extraction hood; - a control device configured to receive input information representative of the value of the carbon monoxide concentration measured by the carbon monoxide sensor, and to control said flow of oxidant injected by said oxidant injector and / or said flow of fuel injected by said fuel injector, according to said input information.

[0013] The provisions described above make it possible to propose an aluminum waste melting system capable of melting aluminum waste to obtain liquid aluminum, while also allowing the volatile organic compounds to be burned inside the melting chamber. The presence of the carbon monoxide sensor communicating with the control device also allows the oxidizer and fuel flow rates to be controlled to keep the VOC level at the outlet of the melting furnace below a regulatory limit.

[0014] Advantageously, the use of a fume hood at the melting furnace exhaust system allows for the rapid cooling of combustion fumes by mixing them with the open air directly at the furnace outlet, while simultaneously capturing said combustion fumes. In this way, it is possible to limit the formation of dioxins in the combustion fumes, while ensuring the capture of all cooled combustion fumes at the melting furnace outlet.

[0015] The fusion system may also have one or more of the following characteristics, taken alone or in combination.

[0016] According to one embodiment, the melting furnace includes a material introduction door configured to allow the introduction of aluminum scrap into the melting chamber. In this case, the material introduction door is opened to introduce the aluminum scrap into the melting chamber.

[0017] By "control" it is meant that the control device is capable of regulating or varying the flow rates of oxidant and / or fuel introduced into the furnace enclosure, for example through one or more valves.

[0018] According to one embodiment, the control device is an automated system configured to automatically control the flow rate of oxidant injected by the oxidant injector, and / or the flow rate of fuel injected by the fuel injector, and / or optionally the rotational speed of the rotary drum, for example, according to an algorithm stored in the control device's memory. Such an algorithm may include instructions corresponding to operating modes of a control step of the fusion process according to the invention.

[0019] According to one embodiment, the melting furnace is a rotary furnace comprising a rotating drum configured to be rotated.

[0020] In this way, it is possible to accelerate or slow down the combustion of organic coatings by rotating the rotating drum.

[0021] According to another embodiment, the melting furnace is a multi-chamber furnace.

[0022] According to one embodiment, the means for evacuating the melting furnace include at least one opening provided in a wall of the melting furnace.

[0023] According to one embodiment, at least one opening is disposed at the level of a door of the melting furnace, for example on an upper portion of said door.

[0024] The above-described provisions allow for the design of a door that is not airtight against combustion fumes. The design and manufacture of such a door is therefore easier compared to aluminum scrap melting systems in which the door is airtight. It is thus possible to design and manufacture large rotary melting furnaces capable of receiving a greater quantity of aluminum scrap.

[0025] Advantageously, the presence of the extraction hood also prevents the escape of combustion fumes outside the aluminum waste melting system, and thus limits diffusion in the workshop in which the melting furnace is located.

[0026] According to one embodiment, the carbon monoxide sensor comprises a laser emitter configured to emit laser radiation, and a laser receiver configured to receive said emitted laser radiation, and to measure an absorption spectrum of said received laser radiation, the value of the carbon monoxide concentration being determined from said absorption spectrum thus measured.

[0027] In other words, the carbon monoxide sensor measures the value of the carbon monoxide concentration by a measurement method by laser absorption spectrometry, also called TDLAS for "Tunable diode laser absorption spectroscopy" according to the established Anglo-Saxon terminology.

[0028] Advantageously, the use of a laser absorption spectrometry measurement method with the carbon monoxide sensor makes it possible to measure the carbon monoxide concentration with a sensitivity of approximately 0.3 ppm in a time interval of less than 1 second. This is particularly advantageous for performing near-real-time control of the melting furnace to monitor the combustion of volatile organic compounds.

[0029] Moreover, such a carbon monoxide sensor has the advantage of being a non-contact measurement method, facilitating maintenance.

[0030] Finally, this online spectrometry measurement method limits interference with other gases, making the measurement reliable.

[0031] According to one embodiment, the melting furnace includes an additional oxidizer lance separate from at least one oxidizer injector, and configured to to allow the introduction of an additional flow of oxidant inside the fusion chamber.

[0032] According to one embodiment, the additional oxidizer lance has a maximum oxidizer introduction flow rate into the fusion chamber which is strictly greater than a maximum oxidizer introduction flow rate of at least one oxidizer injector.

[0033] The above-described provisions make it possible to propose a melting furnace with improved oxidant injection capabilities, which is particularly suitable for improving the combustion of volatile organic compounds inside the melting chamber.

[0034] According to one embodiment, the oxidizer injector is an oxygen injector industrially pure.

[0035] According to one embodiment, the additional oxidizer lance is an industrially pure oxygen lance.

[0036] In this way, it is possible to improve the combustion of volatile organic compounds without cooling the inside of the melting furnace. This is particularly advantageous for reducing the time and therefore the energy required to melt a given quantity of aluminum scrap compared to a melting furnace using an oxidant containing less than 100% oxygen, typically air or oxygen-enriched air.

[0037] According to one embodiment, the control duct for the extraction hood comprises an extraction end at which the combustion fumes are captured, and a filtration end, opposite the extraction end, said filtration end being equipped with a dust filter configured to filter combustion products separate from the VOCs remaining in the combustion fumes, at the filtration end. Advantageously, the dust filter may be a lime filter configured both to capture the dust remaining in the combustion fumes and to neutralize acidic fumes such as hydrochloric acid (HCl).

[0038] In this way, it is possible to filter the combustion fumes before they escape outside the aluminum waste melting system.

[0039] According to one embodiment, the fusion system includes a carbon dioxide trap disposed at the filtration end, said carbon dioxide trap being configured to trap all or part of the carbon dioxide present in the combustion fumes before they are evacuated from the fusion system.

[0040] The object of the invention can also be achieved through the implementation of a process for melting aluminum waste using an aluminum waste melting system, the melting process comprising: - a step of making available an aluminium waste melting system as described above; - a first introduction stage in which a first quantity of said aluminium waste is introduced into the melting chamber of the melting furnace; - a melting stage in which the ignition device is lit so that the burner brings heat into the melting chamber of the melting furnace when it is supplied with oxidizer and fuel respectively by the oxidizer injector, and by the fuel injector, said melting stage leading to the formation by melting of liquid aluminium, and to the formation of combustion fumes; - a measurement step in which the carbon monoxide sensor measures the value of the carbon monoxide concentration in the combustion fumes captured by the extraction hood; - a piloting step in which the control device receives input information representative of the value of the carbon monoxide concentration measured by the carbon monoxide sensor, and controls the flow of oxidant injected by the oxidant injector, and / or controls the flow of fuel injected by the fuel injector, according to said input information.

[0041] The provisions described above make it possible to propose a melting process which makes it possible both to form liquid aluminium from aluminium waste and to limit the quantity of volatile organic compounds in the combustion fumes evacuated from the melting chamber of the melting furnace by the thermolysis of said volatile organic compounds in-situ in the melting furnace.

[0042] The fusion process may also have one or more of the following characteristics, taken alone or in combination.

[0043] According to one embodiment, the first introduction step further includes the introduction of at least one salt, so as to obtain a slag denoted "L" covering the liquid aluminum and comprising alumina and said at least one salt during the melting step.

[0044] Advantageously, the introduction of at least one salt during the first The introduction step allows for the trapping of solid residual organic compounds that originate from the thermolysis of organic materials present in aluminum waste.

[0045] According to one embodiment, the melting process includes a step of emptying the melting furnace, in which all or part of the liquid aluminum contained in The melting chamber is extracted from the melting chamber, typically by tilting or siphoning.

[0046] According to one embodiment, during the piloting step, the control device controls the flow rate of oxidant injected by the oxidant injector, and / or the flow rate of fuel injected by the fuel injector according to the following operating modes: - a first mode of operation in which the oxidant flow rate and the fuel flow rate are chosen to introduce the oxidant and the fuel into the fusion chamber in stoichiometric proportions, the first mode of operation being established if the value of the carbon monoxide concentration is strictly less than a first threshold; - a second operating mode in which a ratio between the oxidant flow rate and the fuel flow rate is varied between an initial ratio corresponding to an introduction under stoichiometric conditions of oxidant and fuel into the fusion chamber respectively by the oxidant injector and the fuel injector, and a maximum ratio corresponding to a zero flow rate of fuel introduced by the fuel injector into the fusion chamber and a maximum oxidant flow rate introduced by the oxidant injector into the fusion chamber, said ratio between the oxidant flow rate and the fuel flow rate being varied according to the value of the measured carbon monoxide concentration, the second operating mode being established if the value of the carbon monoxide concentration is strictly less than a second threshold and greater than or equal to the first threshold; - a third operating mode in which the oxidizer flow rate is set to the maximum oxidizer flow rate value, the fuel flow rate is stopped, and the ignition device is switched off, the third operating mode being established if the value of the carbon monoxide concentration is strictly less than a third threshold and greater than or equal to the second threshold; - a fourth operating mode in which the oxidizer flow rate is set to a maximum flow rate value, the fuel flow rate is stopped, the ignition device is switched off, the fourth operating mode being established if the value of the carbon monoxide concentration is strictly greater than the third threshold.

[0047] According to one embodiment, if the melting furnace is a rotary furnace comprising a rotating drum, the fourth operating mode further includes the variation, and in particular the reduction, of the rotation speed of the rotating drum.

[0048] According to one embodiment, the first threshold is strictly less than the second threshold.

[0049] According to one embodiment, the second threshold is substantially equal to five times the value of the first threshold.

[0050] According to one embodiment, the second threshold is strictly less than the third threshold.

[0051] According to one embodiment, the third threshold is substantially equal to twice the value of the second threshold.

[0052] According to one embodiment, the first threshold is substantially equal to 30 ppm.

[0053] According to one embodiment, the second threshold is approximately equal to 150 ppm.

[0054] According to one embodiment, the third threshold is approximately equal to 300 ppm.

[0055] By "approximately equal to", we mean "within 10%".

[0056] Advantageously, controlling the oxidizer and fuel injectors makes it possible both to limit the formation of volatile organic compounds and to protect against the risks of over-oxidation. Indeed, if the oxidizer and fuel injectors are placed in the second, third, and fourth operating modes, the excess oxidizer is consumed to limit the formation of volatile organic compounds and does not oxidize the liquid aluminum. Moreover, and advantageously, if the melting process includes the introduction of at least one salt, the slag formed acts as a shield against the oxidation of the liquid aluminum by the injected oxidizer.

[0057] According to one embodiment, the fourth operating mode further includes the introduction of an additional flow of oxidizer into the fusion chamber by the additional lance.

[0058] In this way, it is possible to increase the amount of oxidant introduced into the melting chamber, and to destroy by combustion a greater quantity of volatile organic compounds without decreasing the melting temperature of the melting furnace.

[0059] According to one embodiment, the first operating mode includes implementing a second introduction step in which a second quantity of aluminum scrap is introduced into the melting chamber of the smelting furnace. For example, the second introduction step may be implemented when the control device drives the oxidizer flow rate and the fuel flow rate in the first operating mode directly after having driven the oxidizer flow rate and the fuel flow rate in an operating mode selected from the second, third, or fourth operating mode.

[0060] Thus, it is possible to adjust the quantity of aluminum waste introduced into the melting chamber without first measuring the quantity of organic compounds volatiles in aluminum waste. The melting yield of liquid aluminum is thus increased.

[0061] According to one embodiment, during the piloting step, if the ignition device is off, and if the carbon monoxide concentration is strictly less than a restart threshold value, then the ignition device is switched on, the restart threshold value being strictly greater than the first threshold and strictly less than the second threshold. For example, the restart threshold value is approximately 1.5 times the value of the first threshold.

[0062] According to one embodiment, the restart threshold value is substantially equal to 45 ppm.

[0063] Advantageously, reigniting the ignition device once the carbon monoxide concentration falls below a sufficiently low threshold allows the aluminum melting process to restart and limits the formation of oxides on the surface of the liquid aluminum. This arrangement makes it possible to account for potential hysteresis phenomena during the melting of the metal and the combustion of organic coatings, which are related to the inertia of the melting furnace 10.

[0064] According to one embodiment, the fusion process includes a calibration step, in which a correlation law is established between: - an average carbon monoxide concentration measured by the carbon monoxide sensor, and - an average concentration of volatile organic compounds measured at the filtration end by a volatile organic compound sensor, The correlation law is established based on at least three average carbon monoxide concentration values ​​measured by the carbon monoxide sensor, each associated with an average volatile organic compound (VOC) concentration value measured over the same time interval. In one embodiment, the correlation law is in the form of a linear equation and is established using a linear regression method. Indeed, the applicant surprisingly found that it was possible to establish a linear relationship between the average carbon monoxide concentration at the outlet of the melting furnace and the average VOC concentration at the filtration end. This correlation law is particularly dependent on the melting system used, as it depends specifically on the melting furnace, the extraction hood, and the dilution rate of the combustion fumes in the open air before their capture by the extraction hood.

[0065] According to one embodiment, the average concentration of volatile organic compounds measured at the filtration end by a compound sensor volatile organic compounds are measured downstream of the dust filter, that is, after the dust filter has filtered the combustion fumes.

[0066] For example, the time interval corresponds to a melting cycle, which is the time interval between the introduction of the first quantity of aluminum scrap and the draining of the liquid aluminum. During this melting cycle, an average carbon monoxide concentration is measured by calculating the arithmetic mean of the carbon monoxide concentration values ​​measured by the carbon monoxide sensor over said melting cycle. During the same melting cycle, an average VOC concentration is measured by calculating the arithmetic mean of the VOC concentration values ​​measured by the VOC sensor. This average VOC concentration is then associated with the average carbon monoxide concentration.This operation is repeated at least three times to obtain at least three pairs of average carbon monoxide and VOC concentration values, allowing a linear equation to be established in the form [vco]™ = " * Cm where [vco]m is the average VOC concentration measured over a cycle expressed in milligrams of carbon equivalent per normal cubic meters (mg / Nm3), Cm is the average carbon monoxide concentration measured over a cycle expressed in ppm, and a is a positive real coefficient. For example, the coefficient a is approximately equal to 0.4.

[0067] According to one embodiment, the restart threshold value, the first threshold, the second threshold, and the third threshold are determined at the end of the calibration step. For example, said thresholds can be determined to limit emissions of volatile organic compounds below defined thresholds, for example, by use or by regulatory requirements.

[0068] For example, the first threshold may correspond to the following formula: 7 if $5 L

[0069] The second threshold can correspond to the following formula: 52=.;«^

[0070] The third threshold can correspond to the following formula: 53 = - [raV],™^ you

[0071] The restart threshold value may correspond to the following formula: Sr =

[0072] where a is the coefficient determined by establishing the linear equation described above, and

[0073] where [C0V]max is a maximum average VOC concentration value over a melting cycle, arbitrarily set by the user, or by regulatory or normative requirements.

[0074] According to one embodiment, the melting process further comprises a cooling step, in which the combustion fumes are diluted and cooled in open air outside the melting chamber. It is understood that in a melting cycle, the cooling step and the measurement step can be carried out simultaneously and continuously.

[0075] The arrangements described above allow the combustion fumes to be cooled outside the melting chamber in open air. This cooling step is particularly advantageous because it allows the combustion fumes to be diluted and cooled while minimizing the formation of toxic dioxins.

[0076] For example, the cooling stage includes an evacuation stage in which the evacuation means are operated to allow the evacuation of the combustion fumes produced during the melting stage outside the melting enclosure and into the open air, and a suction stage in which the suction hood captures by suction the combustion fumes present in the open air outside the melting furnace.

[0077] According to one embodiment, the piloting step is carried out after the measurement step within the same phase and said phase is repeated over time, in particular in a cyclical or periodic manner.

[0078] According to one embodiment, the measurement step is implemented several times over a piloting time interval, so as to implement the piloting step several times over said piloting time interval.

[0079] According to one embodiment, the measurement and control steps are implemented continuously and in real time over the control interval. Thus, it is possible to control the melting furnace in real time during the control process. In this way, it is possible to optimize the melting time of the quantity of aluminum scrap, while limiting the amount of volatile organic compounds released from the melting chamber. Brief description of the drawings

[0080] Other aspects, objectives, advantages and features of the invention will become clearer upon reading the following detailed description of preferred embodiments of this, given by way of non-limiting example, and made with reference to the attached drawings on which:

[0081] [Fig.1] Fig.1 is a schematic view of a fusion system according to a particular embodiment of the invention.

[0082] [Fig.2] The [Fig.2] is a schematic view of a melting process according to a particular embodiment of the invention. Detailed description

[0083] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to enhance the clarity of the figures. Moreover, the different embodiments and variants are not mutually exclusive and may be combined.

[0084] As illustrated in [Fig. 1], the invention relates to a system for melting aluminum waste. Such aluminum waste may, for example, consist of beverage cans that have been compacted together to form a mass of waste to be melted.

[0085] The melting system 1 includes first of all a melting furnace 10 intended for melting said aluminum waste. According to a first variant, the melting furnace 10 is a rotary furnace, but such a variant is not limiting and it is also possible that the melting furnace 10 is a multi-chamber furnace, or any other furnace suitable for melting aluminum, i.e. capable of placing a mass of waste at a temperature above 660°C.

[0086] The melting furnace 10 includes a drum 11 which internally delimits a melting chamber 13 for receiving the aluminum waste to be melted. According to the previously described embodiment in which the melting furnace 10 is a rotary furnace, the drum 11 is a rotary drum configured to be rotated. In this way, it is possible to accelerate or slow down the combustion of the organic coatings by rotating the drum 11.

[0087] The melting furnace 10 also includes a burner 20 comprising an ignition device 21, at least one oxidizer injector 23, and at least one fuel injector 25.

[0088] The oxidizer injector 23 is configured to inject a flow of oxidizer into the melting chamber 13. It is generally coupled to an oxidizer supply located outside the melting furnace 10, as well as to an oxidizer valve for varying the flow rate of oxidizer injected into the melting chamber 13. Such an oxidizer valve can advantageously be actuated automatically, so as to be able to control or vary The burner automatically regulates the flow of oxidizer injected into the combustion chamber 13. In one embodiment, the burner 20 comprises a central oxidizer injector 23 located near the ignition device 21, and four peripheral oxidizer injectors 23 arranged at equal distances from the central oxidizer injector 23. However, this configuration is not limited, and the burner 20 may comprise one or more oxidizer injectors 23 arranged in a different manner.

[0089] Advantageously, the oxidizer injector 23 can be an injector of industrially pure oxygen. In this way, it is possible to improve the combustion of volatile organic compounds (VOCs) without cooling the inside of the melting furnace 10. This is particularly advantageous for reducing the time and therefore the energy required to melt a given quantity of aluminum scrap compared to a melting furnace 10 using an oxidizer containing less than 100% dioxygen, typically air or oxygen-enriched air.

[0090] The fuel injector 25 is configured to inject a flow of fuel into the melting chamber 13. It is generally coupled to a fuel supply located outside the melting furnace 10, as well as to a fuel valve for varying the flow of fuel injected into the melting chamber 13. Such a fuel valve can also be actuated automatically, so as to be able to control or automatically vary the flow of fuel inserted into the combustion chamber 13. According to one embodiment, the burner 20 may include a single fuel injector 25 located near the central oxidizer injector 23 and the ignition device 21.

[0091] The ignition device 21 is configured to start combustion of the oxidizer and fuel injected into the melting chamber 13, in order to supply heat to the melting chamber 13. Thus, the burner 20 is able to allow the melting of the aluminum waste in the melting chamber 13. Furthermore, the melting furnace 10 allows the combustion of the organic compounds present in the aluminum waste.

[0092] As illustrated in [Fig. 1], the melting furnace 10 may also include an additional oxidizer lance 27 separate from at least one oxidizer injector 23, and configured to allow the introduction of an additional flow rate of oxidizer into the melting chamber 13. This additional oxidizer lance 27 is not generally included in the burner 20. It may, for example, have a maximum flow rate of oxidizer introduction into the melting chamber 13 that is strictly greater than the maximum flow rate of oxidizer introduction from at least one oxidizer injector 23. In the same way that For the oxidizer injector 23, the additional oxidizer lance 27 can be an industrially pure oxygen lance. The arrangements described above allow for a melting furnace 10 with improved oxidizer injection capabilities, which is particularly suitable for improving the combustion of volatile organic compounds (VOCs) inside the melting chamber 13.

[0093] The melting furnace 10 finally includes exhaust means 17 configured to allow the extraction of all or part of the combustion fumes, denoted "F", from inside the melting chamber 13 to an open air zone located outside the melting chamber 13 and where air is free to circulate. As illustrated in [Fig. 1], the melting furnace 10 may include a material introduction door 15 configured to allow the introduction of aluminum waste into the melting chamber 13 when this door 15 is open. For example, the exhaust means 17 of the melting furnace 10 may consist of at least one opening in a wall of the melting furnace 10, for example at the door 15 of the melting furnace 10 which is used for material introduction. In [Fig.[l] The evacuation means 17 comprise a single opening located on an upper portion of the door 15; however, it is understood that the evacuation means 17 may also comprise several openings. The arrangements described above allow for a door 15 that is not airtight to combustion fumes F. The design and manufacture of such a door 15 is therefore facilitated compared to aluminum scrap melting systems in which the door 15 is airtight. It is thus possible to design and manufacture large rotary melting furnaces 10 capable of receiving a greater quantity of aluminum scrap.

[0094] The aluminum waste melting system 1 further includes a suction hood 30 located outside the melting chamber 13 and designed to capture by suction all or part of the combustion fumes F present in the open air zone. The suction hood 30 includes a control duct 31 which may include a suction end 33 at which the combustion fumes F are captured. For example, this suction end 33 may be located at the exhaust means 17 of the melting furnace 10. In this way, it is possible to rapidly cool the combustion fumes F by mixing them with the open air directly at the furnace outlet, while simultaneously capturing said combustion fumes F. The formation of dioxin by de novo synthesis in the combustion fumes F is thus limited, and the combustion fumes F are cooled and captured directly at the outlet of the melting furnace 10.In other words, the presence of the extraction hood 30 prevents the escape of combustion fumes F outside the aluminum waste melting system 1 and thus limits the diffusion in the workshop in which the melting furnace 10 is located.

[0095] The control line 31 of the extraction hood 30 may also include a filter end 35 opposite the extraction end 33. This filter end 35 may advantageously be equipped with a dust filter 39 configured to filter combustion products separate from the VOCs remaining in the combustion fumes F, at the level of the filter end 35. Advantageously, the dust filter 39 may be a lime filter configured both to capture the remaining dust in the combustion fumes and to neutralize acidic fumes such as hydrochloric acid (HCl). In this way, it is possible to filter the combustion fumes F before they escape outside the aluminum waste melting system 1.According to an unrepresented variant, the fusion system 1 includes a carbon dioxide trap disposed at the filtration end 35, said carbon dioxide trap being configured to trap all or part of the carbon dioxide present in the combustion fumes F before their evacuation from the fusion system 1.

[0096] The control line 31 includes at least one carbon monoxide sensor 37 configured to measure a carbon monoxide concentration value, denoted "C", in the combustion fumes F captured by the extraction hood 30. For example, the carbon monoxide sensor 37 includes a laser emitter configured to emit laser radiation, and a laser receiver configured to receive said emitted laser radiation and to measure an absorption spectrum of said received laser radiation, the value of the carbon monoxide concentration C being determined from said absorption spectrum thus measured. In other words, the carbon monoxide sensor 37 measures the value of the carbon monoxide concentration C by a laser absorption spectrometry measurement method, also known as TDLAS for "Tunable diode laser absorption spectroscopy" according to established Anglo-Saxon terminology.Advantageously, the use of laser absorption spectrometry with the carbon monoxide sensor 37 allows for the measurement of carbon monoxide concentration (C) with a sensitivity of approximately 0.3 ppm in less than 1 second. This is particularly advantageous for near real-time control of the melting furnace 10 to monitor the combustion of volatile organic compounds. Furthermore, such a carbon monoxide sensor 37 offers the advantage of being a non-contact measurement method, simplifying maintenance. Finally, this online spectrometric measurement method minimizes interference from other gases, ensuring reliable measurements.

[0097] Finally, the aluminum waste melting system 1 includes a control device 50 configured to receive input information representative of the carbon monoxide concentration value C measured by the sensor of carbon monoxide 37, and to control the flow rate of oxidizer injected by said oxidizer injector 23 and / or the flow rate of fuel injected by said fuel injector 25, according to said input information. By "control," it is understood that the control device 50 is capable of regulating or varying the flow rates of oxidizer and / or fuel introduced into the furnace chamber, for example, via one or more valves. Generally, the control device 50 is an automated system configured to automatically control the flow rate of oxidizer injected by the oxidizer injector 23 and / or the flow rate of fuel injected by the fuel injector 25, and / or optionally the rotational speed of the rotating drum 11, for example, according to an algorithm stored in a memory of the control device 50.Such an algorithm could include instructions corresponding to operating modes of a control step E6 of the fusion process, which will be described later.

[0098] The arrangements described above make it possible to propose an aluminum waste melting system 1 capable of melting aluminum waste to obtain liquid aluminum, denoted "M", while allowing the burning of volatile organic compounds (VOCs) inside the melting chamber 13. The presence of the carbon monoxide sensor 37 communicating with the control device 50 also makes it possible to control the oxidizer and fuel flow rates to keep the VOC level at the outlet of the melting furnace 10 below a safety value.

[0099] The invention also relates to a process for melting aluminum waste using an aluminum waste melting system 1. At the end of the melting process, a step is generally carried out to empty the melting furnace 10 (not shown), in which all or part of the liquid aluminum M contained in the melting chamber is extracted from the melting chamber 13, typically by tipping or siphoning.

[0100] An embodiment of the melting process is shown for example in [Fig.2]. The melting process first includes a step of making available El a melting system 1 of aluminium waste of the type of one of those described previously.

[0101] Prior to implementing other steps of the melting process, it may be advantageous to carry out a calibration step Eli, in which control parameters for the melting furnace 10 are determined. As we will see later, these control parameters can be used in a control step E6, which is then implemented differently depending on these furnace control parameters, i.e., depending on the type of melting furnace 10 used, or depending on the size of this melting furnace 10. During the calibration step Eli, a correlation law, for example in the form of a linear equation, is established between: - an average carbon monoxide concentration Cm measured by the carbon monoxide sensor 37, and - an average concentration of volatile organic compounds [VOCs]m measured at the filtration end 35 by a volatile organic compound VOC sensor.

[0102] For example, such a correlation law is established by a linear regression method based on at least three average carbon monoxide concentration values ​​Cm determined from measurements of the carbon monoxide sensor 37, each associated with an average volatile organic compound (VOC) concentration value [VOC]m determined over the same time interval. Indeed, the applicant has surprisingly found that it is possible to establish a linear relationship between the average carbon monoxide concentration Cm at the outlet of the melting furnace 10 and the average VOC concentration [VOC]m at the filtration end 35. This correlation law is dependent on the melting system 1 used, as it depends in particular on the melting furnace 10, the extraction hood 30, and the dilution rate of the combustion fumes F in the open air before their capture by the extraction hood 30.

[0103] According to one embodiment, the average concentration of volatile organic compounds measured at the filtration end 35 by a volatile organic compound sensor is measured downstream of the dust filter 39, i.e. after the dust filter 39 has filtered the combustion fumes F.

[0104] For example, the time interval corresponds to a melting cycle, which is the time interval between the introduction of the first quantity of aluminum scrap and the step of draining the liquid aluminum M. During this melting cycle, an average carbon monoxide concentration value Cm is measured by calculating an arithmetic mean of the carbon monoxide concentration values ​​C measured by the carbon monoxide sensor 37 over said melting cycle. Over the same melting cycle, an average VOC concentration value [VOC]m is measured by calculating an arithmetic mean of the VOC concentration values ​​[VOC] measured by the VOC sensor.

[0105] This average VOC concentration value [VOC]m is then associated with the average carbon monoxide concentration value Cm. This operation is repeated at least three times to obtain at least three pairs of average carbon monoxide concentration values ​​Cm and VOC [VOC]m, allowing a linear equation to be established in the form (covj = " " cm, where [VOC]m is the concentration The average VOC concentration measured over a cycle is expressed in milligrams of carbon equivalent per normal cubic meters (mg / Nm3), Cm is the average carbon monoxide concentration measured over a cycle expressed in ppm, and a is a positive real coefficient. For example, the coefficient a determined in this case is equal to 0.4.

[0106] It is then possible to determine a restart threshold value Sr, a first threshold SI, a second threshold S2, and a third threshold S3 at the end of the calibration step Eli, which constitute the control parameters that can be used in the control step E6. For example, said thresholds can be determined to limit emissions of volatile organic compounds VOCs below thresholds defined, for example by use, or by normative requirements.

[0107] For example, the first SI threshold may correspond to the following formula: si = — ïcovi Sa;L

[0108] The second threshold S2 can correspond to the following formula:

[0109] The third threshold S3 can correspond to the following formula: ^3 — — [COVj^a*.

[0110] The restart threshold value Sr can correspond to the following formula:

[0111] where a is the coefficient determined by establishing the linear equation described above, and

[0112] where [C0V]max is a maximum average VOC concentration value over a cycle, arbitrarily set by the user, or by regulatory or normative requirements.

[0113] Although such values ​​are not limiting, setting such thresholds by the correlation law, based on the maximum average VOC concentration value over a cycle, arbitrarily set by the user, or by regulatory or normative requirements, makes it possible to guarantee that VOC emissions will remain on average over a melting cycle contained at values ​​below the regulatory thresholds.

[0114] The melting process then comprises a first introduction step E21 in which a first quantity of said aluminum waste is introduced in the melting chamber 13 of the melting furnace 10. The first introduction step E21 can also include the introduction of at least one salt along with the aluminum scrap. Thus, during the melting step described later, it is possible to obtain a slag L covering the liquid aluminum M and comprising alumina and said at least one salt. Advantageously, the introduction of at least one salt during the first introduction step E21 allows for the trapping of residual solid organic compounds (polycyclic aromatic hydrocarbons, soot, etc.) that result from the thermolysis of organic materials present in the aluminum scrap. This slag L also has the advantage of forming a protective layer against oxidation, which is particularly useful during all stages of the melting process, and especially during the pilot stage E6.

[0115] Once the first materials necessary for melting have been introduced into the furnace, the melting process includes a melting step E3 in which the ignition device 21 is lit so that the burner 20 brings heat into the melting chamber 13 of the melting furnace 10 when it is supplied with oxidizer and fuel respectively by the oxidizer injector 23, and by the fuel injector 25. This melting step E3 thus leads to the formation by melting of liquid aluminium M, and to the formation of combustion fumes F, but also of slag L if a salt has been introduced into the melting chamber 13.

[0116] The melting process generally includes a cooling step E4, in which the combustion fumes F are diluted and cooled in open air outside the melting chamber 13. As can be seen in [Fig. 1], the cooling step E4 may include an exhaust step in which the exhaust means 17 are operated to allow the exhaust of the combustion fumes F produced during the melting step E3 outside the melting chamber 13 and into open air. Subsequently, a suction step may be implemented, in which the suction hood 30 captures by suction the combustion fumes F present in the open air outside the melting furnace 10. The arrangements described above allow the combustion fumes F to be cooled outside the melting chamber 13 in open air.This E4 cooling stage is particularly advantageous because it allows the combustion fumes F to be diluted and cooled, minimizing the formation of toxic dioxins.

[0117] Once the combustion fumes F are captured by the extraction hood 30, the melting process includes the measurement step E5 in which the carbon monoxide sensor 37 measures the concentration of carbon monoxide C in the combustion fumes F. This measurement step E5 makes it possible to determine the concentration of carbon monoxide C in the combustion fumes F in real time, and very quickly after these combustion fumes F have been formed. This is particularly advantageous, as it allows for a very rapid determination of the VOC concentration in the combustion fumes F, when referring to the formula established during the calibration step Eli, for example. It is well understood that in a melting cycle, the cooling step E4 and the measurement step E5 can be implemented simultaneously and continuously.

[0118] The melting process also includes the pilot step E6 in which the control device 50 receives input information representing the value of the carbon monoxide concentration C measured by the carbon monoxide sensor 37, and controls the flow rate of oxidant injected by the oxidant injector 23, and / or controls the flow rate of fuel injected by the fuel injector 25, according to said input information. "Control" means that the control device 50 is capable of regulating or varying the flow rates of oxidant and / or fuel introduced into the furnace chamber, for example, via one or more valves.

[0119] In particular, and as detailed in the non-limiting embodiment of [Fig.2], during the piloting step E6, the control device 50 controls the flow rate of oxidant injected by the oxidant injector 23, and / or the flow rate of fuel injected by the fuel injector 25 according to the following operating modes.

[0120] A first operating mode Modl includes selecting the oxidizer flow rate and the fuel flow rate to introduce the oxidizer and fuel into the melting chamber 13 in stoichiometric proportions. This first operating mode Modl is established if the carbon monoxide concentration C is strictly below the first SI threshold, for example, as determined during the calibration step Eli. In one embodiment, the first SI threshold is substantially equal to 25 ppm, 30 ppm, 35 ppm, or 40 ppm. Optionally, the first operating mode Modl may also include implementing a second introduction step E22 in which a second quantity of aluminum scrap is introduced into the melting chamber 13 of the melting furnace 10.For example, it can be envisaged that the second introduction step E22 will be implemented when the control device 50 drives the oxidizer flow rate and the fuel flow rate in the first operating mode directly after having driven the oxidizer flow rate and the fuel flow rate in an operating mode selected from a second, third, or fourth operating mode, which are described below. Thus, it is possible to adjust the quantity of aluminum scrap introduced into the melting chamber 13 without first measuring the quantity of volatile organic compounds (VOCs) in the aluminum scrap. The melting yield of liquid aluminum M is thereby increased.

[0121] A second operating mode comprises varying the ratio between the oxidizer flow rate and the fuel flow rate. This ratio is varied between an initial ratio corresponding to the introduction of the oxidizer and fuel under stoichiometric conditions into the fusion chamber 13, and a maximum ratio corresponding to a zero fuel flow rate introduced into the fusion chamber 13 and a maximum oxidizer flow rate introduced into the fusion chamber 13 by the oxidizer injector 23, said ratio between the oxidizer flow rate and the fuel flow rate being varied according to the value of the carbon monoxide concentration C measured by the carbon monoxide sensor 37. It is therefore clearly understood that in the second operating mode Mod2, the oxidizer is always introduced either under stoichiometric conditions with respect to the fuel, or in excess.To achieve this, it is possible either to increase the flow rate of oxidizer introduced into the fusion chamber 13 by the oxidizer injector 23, or to decrease the flow rate of fuel introduced into the fusion chamber 13 by the fuel injector 25, or both. The variation in the ratio between the fuel flow rate and the oxidizer flow rate introduced into the fusion chamber 13 can be proportional to the carbon monoxide concentration C, or related to the carbon monoxide concentration by an exponential relationship or any other relationship determined by those skilled in the art, for example, experimentally. This second operating mode Mod2 is established if the value of the carbon monoxide concentration C is strictly less than a second threshold S2 and greater than or equal to the first threshold SI. Thus, the first threshold SI is strictly less than the second threshold S2.According to one embodiment, the second threshold S2 is substantially equal to 125 ppm, 150 ppm, 175 ppm, or 200 ppm. More generally, the second threshold S2 may be substantially equal to five times the value of the first threshold SI. By "substantially equal," we mean within ±10%.

[0122] A third operating mode Mod3 comprises setting the oxidizer flow rate to the maximum oxidizer flow rate value, stopping the fuel flow, and switching off the ignition device 21. This third operating mode Mod3 is established if the carbon monoxide concentration C is strictly less than a third threshold S3 and greater than or equal to the second threshold S2. Thus, the second threshold S2 is strictly less than the third threshold S3. In one embodiment, the third threshold S3 is substantially equal to 250 ppm, 300 ppm, 350 ppm, or 400 ppm. More generally, the third threshold S3 may be substantially equal to twice the value of the second threshold S2.

[0123] Since the third operating mode Mod3 includes the extinguishing of the ignition device, it is sometimes necessary to restart the melting step E3 once the measured carbon monoxide concentration C has fallen below of a certain threshold, thus saving time on the melting of the aluminum scrap. Therefore, if the ignition device 21 is off, and if the carbon monoxide concentration C is strictly below a restart threshold value Sr, then the ignition device 21 is switched on. The restart threshold value Sr is generally strictly greater than the first threshold S1 and strictly less than the second threshold S2. In one embodiment, the restart threshold value Sr is substantially equal to 37.5 ppm, 45 ppm, 52.5 ppm, or 60 ppm. More generally, the restart threshold value Sr is substantially equal to 1.5 times the value of the first threshold SI. Advantageously, reigniting the ignition device 21 once the carbon monoxide concentration C is below a sufficiently low threshold allows the melting of the aluminum scrap to restart and limits the formation of oxides on the surface of the liquid aluminum M.This provision allows for consideration of possible hysteresis phenomena during the melting of the metal and the combustion of organic coatings, which are linked to the inertia of the melting furnace 10.

[0124] Finally, a fourth operating mode Mod4 includes setting the oxidizer flow rate to a maximum value, stopping the fuel flow rate, and switching off the ignition device 21 if it has not already been switched off. This fourth operating mode Mod4 is established if the carbon monoxide concentration C is strictly greater than the third threshold S3. Advantageously, if the melting furnace 10 is a rotary furnace comprising a rotating drum 11, the fourth operating mode Mod4 also includes varying, and in particular decreasing, the rotational speed of the rotating drum 11. Furthermore, if the melting furnace 10 includes an additional oxidizer nozzle 27, then the fourth operating mode Mod4 also includes introducing an additional flow rate of oxidizer into the melting chamber 13 through the additional nozzle 27.In this way, it is possible to increase the amount of oxidant introduced into the melting chamber 13, and to destroy by combustion a greater quantity of volatile organic compounds VOCs without decreasing the melting temperature of the melting furnace 10.

[0125] Controlling the oxidizer and fuel injectors 23, 25 both limits the formation of volatile organic compounds (VOCs) and protects against the risk of over-oxidation. Indeed, if the oxidizer and fuel injectors 23, 25 are positioned in the second, third, and fourth operating modes Mod2, Mod3, and Mod4, thus in stoichiometric oxidation for gas injection, the excess oxidizer is consumed to limit the formation of VOCs and does not oxidize the liquid aluminum M. Moreover, and advantageously, if the melting process includes the introduction of at least one salt, the slag L formed acts as a shield against the oxidation of the liquid aluminium M by the injected oxidant.

[0126] It is understood that the steps of the melting process described above can be repeated or implemented continuously throughout the entire duration of the aluminum scrap melting process. In particular, the pilot step E6 is carried out after the measurement step E5 within the same phase, and this phase can be repeated over time, notably cyclically, periodically, or continuously. For example, the measurement step E5 can be implemented several times over a pilot time interval so as to implement the pilot step E6 several times over said pilot time interval. Similarly, the measurement step E5 and the pilot step E6 are implemented simultaneously and / or continuously and in real time over the pilot interval. Thus, it is possible to control the melting furnace 10 in real time during the pilot process.In this way, it is possible to optimize the melting time of the quantity of aluminum waste, while limiting the amount of volatile organic compounds (VOCs) released from the melting chamber 13.

[0127] All the arrangements described above make it possible to propose a melting process which makes it possible both to form liquid aluminium M from aluminium waste and to limit the quantity of volatile organic compounds in the combustion fumes F evacuated from the melting chamber 13 of the melting furnace 10 by the thermolysis of said volatile organic compounds in-situ in the melting furnace 10.

Claims

1. Demands Aluminum waste melting system (1) for melting aluminum waste, the melting system (1) comprising: - a melting furnace (10) intended for melting said aluminum waste, and comprising: • a drum (11) internally delimiting a melting chamber (13) intended to receive said aluminum waste to be melted; • a burner (20) comprising an ignition device (21), at least one oxidizer injector (23), and at least one fuel injector (25), said oxidizer injector (23) being configured to inject a flow of oxidizer into the melting chamber (13), said fuel injector (25) being configured to inject a flow of fuel into the melting chamber (13), and the ignition device (21) being configured to start combustion of the oxidizer and fuel injected into the melting chamber (13), to bring heat into the melting chamber (13); • evacuation means (17) configured to allow the extraction of all or part of the combustion fumes (F) from inside the melting enclosure (13) to an open air area located outside the melting enclosure (13) and where the air is free to circulate; - a suction hood (30) located outside the melting chamber (13) and intended to capture by suction all or part of said combustion fumes (F) present in the open air zone, said suction hood (30) further comprising a control line (31) including a carbon monoxide sensor (37) configured to measure a value of a carbon monoxide concentration (C) in said combustion fumes (F) captured by the suction hood (30), the carbon monoxide sensor comprising a laser emitter configured to emit laser radiation, and a laser receiver configured to receive said radiation laser emitted, and to measure an absorption spectrum of said received laser radiation, the value of the carbon monoxide (C) concentration being determined from said absorption spectrum thus measured; - a control device (50) configured to receive input information representative of the value of the carbon monoxide (C) concentration measured by the carbon monoxide sensor (37), and to control said flow of oxidant injected by said oxidant injector (23) and / or said flow of fuel injected by said fuel injector (25), according to said input information.

2. Aluminum waste melting system (1) according to claim 1, wherein the melting furnace (10) is a rotary furnace comprising a rotating drum (11) configured to be rotated.

3. Aluminum waste melting system (1) according to any one of claims 1 or 2, wherein the evacuation means (17) of the melting furnace (10) comprise at least one opening provided in a wall of the melting furnace (10).

4. Aluminum waste melting system (1) according to any one of claims 1 to 3, wherein the melting furnace (10) includes an additional oxidizer lance (27) separate from at least one oxidizer injector (23), and configured to permit the introduction of an additional flow of oxidizer into the melting chamber (13).

5. Aluminum waste melting system (1) according to any one of claims 1 to 4, wherein the oxidizer injector (23) is an industrially pure oxygen injector.

6. Aluminum waste melting system (1) according to any one of claims 1 to 5, wherein the control duct (31) of the extraction hood (30) comprises an extraction end (33) at which combustion fumes (F) are captured, and a filtration end (35), opposite the extraction end (33), said filtration end (35) being provided with a dust filter (39) configured to filter residues remaining in the combustion fumes (F), at the level of the filtration end (35).

7. A process for melting aluminum waste by means of an aluminum waste melting system (1), the melting process comprising: - a step of making available (E1) an aluminum waste melting system (1) according to any one of claims 1 to 6; - a first introduction step (E21) in which a first quantity of said aluminum waste is introduced into the melting chamber (13) of the melting furnace (10); - a melting step (E3) in which the ignition device (21) is lit so that the burner (20) supplies heat to the melting chamber (13) of the melting furnace (10) when it is supplied with oxidizer and fuel respectively by the oxidizer injector (23), and by the fuel injector (25), said melting step (E3) leading to the formation by melting of liquid aluminum (M), and to the formation of combustion fumes (F);- a measurement step (E5) in which the carbon monoxide sensor (37) measures the value of the carbon monoxide concentration (C) in the combustion fumes (F) captured by the extraction hood (30); - a control step (E6) in which the control device (50) receives input information representative of the value of the carbon monoxide concentration (C) measured by the carbon monoxide sensor (37), and controls the flow rate of oxidant injected by the oxidant injector (23), and / or controls the flow rate of fuel injected by the fuel injector (25), according to said input information, the process further comprising a calibration step (Eli), in which a correlation law is established between: - an average carbon monoxide concentration (Cm) measured by the carbon monoxide sensor (37), and;

8.

9. - an average concentration of volatile organic compounds (VOCs) measured at the filtration end (35) by a volatile organic compounds (VOC) sensor, said correlation law being established on the basis of at least three average carbon monoxide concentration values ​​(Cm) measured by the carbon monoxide sensor (37), each associated with an average volatile organic compounds concentration value ([VOC]m) measured over the same time interval. Melting process according to claim 7, wherein the first introduction step (E21) further includes the introduction of at least one salt, so as to obtain a slag (L) covering the liquid aluminium (M) and comprising alumina and said at least one salt during the melting step (E3). A fusion process according to any one of claims 7 or 8, wherein, during the piloting step (E6), the control device (50) controls the flow rate of oxidant injected by the injector of oxidizer (23), and / or the fuel flow rate injected by the fuel injector (25) according to the following operating modes: - a first operating mode (Modl) in which the oxidant flow rate and the fuel flow rate are chosen to introduce the oxidant and the fuel into the fusion chamber (13) in stoichiometric proportions, the first operating mode (Modl) being established if the value of the carbon monoxide concentration (C) is strictly less than a first threshold (SI); - a second operating mode (Mod2) in which the ratio between the oxidizer flow rate and the fuel flow rate is varied between an initial ratio corresponding to the introduction of oxidizer and fuel into the fusion chamber (13) under stoichiometric conditions by the oxidizer injector (23) and the fuel injector (25) respectively, and a maximum ratio corresponding to a zero fuel flow rate introduced by the fuel injector (25) into the fusion chamber (13), and a maximum oxidizer flow rate introduced by the oxidizer injector (23) into the fusion chamber (13), said ratio between the oxidizer flow rate and the fuel flow rate being varied according to the value of the measured carbon monoxide (C) concentration,the second operating mode (Mod2) being established if the value of the carbon monoxide (C) concentration is strictly less than a second threshold (S2) and greater than or equal to the first threshold (SI); - a third operating mode (Mod3) in which the oxidizer flow rate is set to the maximum oxidizer flow rate value, the fuel flow rate is stopped, and the ignition device (21) is switched off, the third operating mode (Mod3) being established if the value of the carbon monoxide concentration (C) is strictly less than a third threshold (S3) and greater than or equal to the second threshold (S2); - a fourth operating mode (Mod4) in which the oxidizer flow rate is set to a maximum flow rate value, the fuel flow rate is stopped, the ignition device (21) is switched off, the fourth operating mode (Mod4) being established if the value of the carbon monoxide concentration (C) is strictly greater than the third threshold (S3).

10. Melting process according to claim 9, wherein the provisioning step (El) comprises the provision of an aluminium waste melting system (1) according to claim 4, and wherein the fourth operating mode (Mod4) further comprises the introduction of an additional flow of oxidant into the melting chamber (13) by the additional lance (27).

11. Melting process according to any one of claims 9 or 10, wherein the first mode of operation (Modl) includes the implementation of a second introduction stage (E22) in which a second quantity of aluminum scrap is introduced into the melting chamber (13) of the melting furnace (10).

12. A melting process according to any one of claims 9 to 11, wherein during the pilot step (E6), if the ignition device (21) is off, and if the value of the carbon monoxide concentration (C) is strictly less than a restart threshold value (Sr), then the ignition device (21) is switched on, the restart threshold value (Sr) being strictly greater than the first threshold (SI) and strictly less than the second threshold (S2).

13. Melting process according to any one of claims 7 to 12, further comprising a cooling step (E4), in which the combustion fumes (F) are diluted and cooled in open air outside the melting enclosure (13).

14. A melting process according to any one of claims 7 to 13, wherein the pilot step (E6) is carried out after the measurement step (E5) within the same phase and said phase is repeated over time, in particular cyclically or periodically.

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