BE1024531B1 - MANUFACTURE OF METALLURGICAL ADDITIVES TITLEED FOR STEELWORK, FOUNDRIES AND THE NON-FERROUS SECTOR - Google Patents

Abstract

The present invention relates to a process for manufacturing aluminum-based products based on an assembly step, that is to say a controlled mixture, or blend, of different types of recycled aluminum products and on less the combination of the following treatment steps: - selective collection of recycled aluminum products from packaging, machining chips or in the form of crushed pieces or fragments (11, 12, 13, 14, 15, 16); - assembling and producing a mixture (1) of recycled products collected in given proportions according to their nature, the selected production route and the intended use; - grinding and screening (2) of the mixture to give a finely divided product; - compaction (3) of the product finely divided into briquettes, billets or blocks (33), and if necessary for final recovery; controlled melting (5) of the briquettes (33); - final shading; - Casting and / or shaping (6) into titrated ingots or granules (52, 61) depending on the customer's request and / or the intended use.

Description

(30) Priority data:

(73) Holder (s):

METALLURGICAL RESEARCH CENTER ASBL- CENTRUM VOOR RESEARCH IN DE METALLURGIE VZW

1000, BRUXELLES Belgique (72) Inventor (s):

MARIQUE Christian 4042 LIERS Belgium

NELIS Adrien 7050 HERCHIES Belgium

DORMANN Marcel 4600 VISE Belgium

HERMAN Jean-Claude 4670 BLEGNY-TREMBLEUR Belgium (54) MANUFACTURE OF TITRATED METALLURGICAL ADDITIVES FOR THE STEEL, FOUNDRY AND NON-FERROUS SECTOR (57) The present invention relates to a process for the manufacture of products based on aluminum based on an assembly step, i.e. a controlled mixture, or blend, of different types of aluminum recycled products and on at least the combination of the following processing steps: selective collection of aluminum recycled products from packaging, machining chips or in the form of crushed parts or fragments (11, 12, 13, 14, 15, 16); - assembly and production of a mixture (1) of recycled products collected in given proportions according to their nature, the selected manufacturing route and the intended use; - grinding and screening (2) of the mixture to give a finely divided product; - compacting (3) of the product finely divided into briquettes, billets or blocks (33), and if necessary for the final recovery; - controlled melting (5) of the briquettes (33); final shade; - casting and / or shaping (6) into titrated ingots or granules (52, 61) depending on the customer's request and / or the intended use.

FIS.Î

BELGIAN INVENTION PATENT

FPS Economy, SMEs, Classes

Medium & Energy

Intellectual Property Office

Publication number: 1024531 Deposit number: BE2016 / 5672

International Classification: C22B 21/00 Date of issue: 04/03/2018

The Minister of the Economy,

Having regard to the Paris Convention of March 20, 1883 for the Protection of Industrial Property;

Considering the law of March 28, 1984 on patents for invention, article 22, for patent applications introduced before September 22, 2014;

Given Title 1 “Patents for invention” of Book XI of the Code of Economic Law, article XI.24, for patent applications introduced from September 22, 2014;

Having regard to the Royal Decree of 2 December 1986 relating to the request, the issue and the maintenance in force of invention patents, article 28;

Considering the patent application received by the Intellectual Property Office on 01/09/2016.

Whereas for patent applications falling within the scope of Title 1, Book XI of the Code of Economic Law (hereinafter CDE), in accordance with article XI. 19, §4, paragraph 2, of the CDE, if the patent application has been the subject of a search report mentioning a lack of unity of invention within the meaning of the §ler of article XI.19 cited above and in the event that the applicant does not limit or file a divisional application in accordance with the results of the search report, the granted patent will be limited to the claims for which the search report has been drawn up.

Stopped :

First article. - It is issued to

METALLURGICAL RESEARCH CENTER ASBL- CENTRUM VOOR RESEARCH IN DE METALLURGIE VZW, Rue Ravenstein 4, 1000 BRUSSELS Belgium;

represented by

PRONOVEM - Office Van Malderen, Zénobe Gramme business park (building K) - Square des Conduites d'eau 1-2, 4020, LIEGE;

a Belgian invention patent with a duration of 20 years, subject to the payment of the annual fees referred to in article XI.48, §1 of the Code of Economic Law, for: MANUFACTURE OF TITRATED METALLURGICAL ADDITIVES FOR SIDERURGY, FOUNDRY AND NON-FERROUS SECTOR.

INVENTOR (S):

MARIQUE Christian, Rue des Ragayets 30, 4042, LIERS;

NELIS Adrien, Rue du Champignon 57, 7050, HERCHIES;

DORMANN Marcel, Rue Marchand 69, 4600, VISE;

HERMAN Jean-Claude, Rue des Brasseurs 98, 4670, BLEGNY-TREMBLEUR;

PRIORITY (S):

DIVISION:

divided from the basic application: filing date of the basic application:

Article 2. - This patent is granted without prior examination of the patentability of the invention, without guarantee of the merit of the invention or of the accuracy of the description thereof and at the risk and peril of the applicant (s) ( s).

Brussels, 04/04/2018, By special delegation:

BE2016 / 5672

MANUFACTURE OF TITRATED METALLURGICAL ADDITIVES FOR

STEEL, FOUNDRY AND THE NON-FERROUS SECTOR

OBJECT OF THE INVENTION The present invention relates to the manufacture, from recycled aluminum products, of new products rich in aluminum valued as titrated additives and suitable for deoxidation and nuancing operations within the framework of the processes. metallurgical and steel industries.

Alternatively, the invention relates to the recycling of aluminum-rich products to transform them into titrated additives for hot coating baths (aluminization, galvanization) of steel and other metallic products.

The present invention is addressed in particular to the recycling of packaging and various residues of aluminum or containing aluminum (machining chips, dismantling residues, ...).

STATE OF THE ART It is known that aluminum is a very interesting metal from the point of view of recycling. It can be recycled indefinitely without loss of quality and remelted using only 5% of the energy required for the production of primary aluminum. In particular, recycling used post-consumer aluminum (such as beverage cans) saves energy and minimizes CO ₂ emissions.

New waste is generated during the production or manufacturing stages, the final product obtained being sold to the consumer.

B E2016 / 5672

Old waste is generated when a product containing aluminum reaches the end of its useful life and is collected and treated by recycling. There are two main types of packaging:

- food and drink cans, aerosol cans, food trays and menu trays, drug blisters where an aluminum foil is welded to a plastic shell, ... also called rigid and semi-rigid packaging;

- flexible packaging in which an aluminum sheet of thickness typically between 5 and 200pm is:

- either used alone in the form of film ("foil" or "aluminum foil") or sachets or sealed packages,

- either co-laminated for example with plastic or cardboard / paper.

Rigid / semi-rigid packaging can generally be qualified as "robust" while flexible packaging can generally be qualified as "light" or "very light".

Aluminum beverage cans constitute the largest part of rigid and semi-rigid packaging. This waste has a high aluminum content (generally> 90%) and therefore a high market value.

In Europe, on average, 70% of cans are harvested. Generally for rigid packaging, the recycling rate is 50% (data: Norsk Hydro).

Flexible packaging waste has a lower overall aluminum content and is very variable when it comes in thin sheets painted and varnished and / or co-laminated with paper and / or plastic. Thus, in the case of sealed foils or packages, the aluminum content can vary in a range from 7-8 to 90%, for example.

According to EN 13920, used drink cans contain on average 94% metallic aluminum, 0.8% oxide and 5.2% foreign material. Coated packaging, less rich in aluminum,

B E2016 / 5672 contain on average 71% metallic aluminum, 3.8% oxide and 24.7% foreign bodies such as paints, varnishes, etc.

Aluminum alloys for wrinkling are aluminum-based alloys intended for processing by forging techniques (rolling, spinning, stamping, etc.). They are designated, under American and European standards (EN 573-1) by a 4-digit numerical system identifying the chemical composition of the alloy. Thus, for example, the 1000 series designates products containing at least 99% aluminum, the 2000 series has copper as the main alloying element (AfeCu, AbCuMg), the 3000 series manganese (AI ₆ Mn), the 5000 series magnesium (Mg2Si), 7000 series zinc (MgZn ₂ ), etc.

Document FR 2 801 060 A1 discloses a process for manufacturing an intermediate product, such as a rolling plate, a spinning billet, a forging block or an ingot, from a specific alloy of the 7000 series. , said determined alloy having a targeted content of at least one first anti-recrystallizing element, chosen from the group consisting of Zr and Cr, said method being characterized in that it comprises:

- the supply of scrap and machining chips comprising scrap and chips in at least one second alloy of the 7000 series having a targeted content of at least one second anti-recrystallizing element, chosen from the group consisting of Zr and Cr, higher than the maximum content accepted in said determined alloy;

- At least one step of refining said scrap and chips making it possible to reduce the content of said second anti-recrystallizing element to a value lower than the maximum content accepted in said determined alloy;

- the development of a batch of liquid metal, in whole or in part, from the refined metal resulting from refining;

- The formation of said product by casting said liquid metal to the title.

B E2016 / 5672 This process makes it possible to recycle scrap and machining chips from 7000 series alloys in the manufacture of intermediate products with high added value.

Document FR 3 023 848 A1 discloses a method for manufacturing an aluminum alloy ingot using aluminum alloy waste from the 2xxx or 7xxx series in which:

- we supply the aluminum alloy waste of the 2xxx or 7xxx series;

- Optionally, the oil present in the waste is separated;

- A first waste treatment operation is carried out with a first liquid at a temperature of at least 10 ° C, said first liquid being an aqueous solution having a pH of 1 to 5 or 8 to 13;

- Separating the first liquid and the waste thus treated;

- at least a second waste treatment operation is carried out using a second liquid;

- Separating the second liquid and the waste thus treated;

- The waste thus obtained is merged;

- an aluminum alloy ingot from the series of waste used is poured.

The ingots obtained by the process can be used for the manufacture after rolling, spinning and / or forging of aeronautical structural elements.

The problem of recycling scrap containing alkali or alkaline earth metal is encountered especially in the aeronautical sector.

Document CN 1401443 A discloses a process for recovering packaging from aluminum-plastic paper with a delaminating agent comprising the immersion of said packaging paper in an acid solution containing nitric acid at a concentration of between 15 and 68% and at a temperature between 40 and 70 ° C, to dissolve the aluminum oxide layer at the junction position, and to separate the aluminum layer from the plastic or paper layer.

BE2016 / 5672 [0018] Document CN 102671913 A describes a global method of use for waste packaging material made of aluminum-plastic paper. The method includes the following steps: grinding, cleaning and drying said material; heating, pyrolysis and gasification of the material dried in an autoclave at high pressure and high temperature under vacuum, and the realization at low temperature of recovery by hardening; placing the paper material mixed with the pyrolyzed and carbonated aluminum plastic in a reaction tank, adding a caustic potassium solution, for the reaction, and recovering the hydrogen generated to serve as special fuel; neutralizing the remaining material with dilute sulfuric acid, and performing filter pressing and washing to obtain a filter cake, namely an aqueous pulp; and complete filtration of the aqueous pulp, evaporation and crystallization of the filtrate obtained and centrifugation to remove the residues so as to recover the potassium alum, in a broad application.

Document US Pat. No. 6,193,780 B1 discloses a process for recovering aluminum and energy from aluminum-plastic packaging as well as an oven for implementing such a process, which includes a pretreatment for recovering paper. , the separation of aluminum and recyclable products by pyrolysis of polyethylene, mainly for their energy content. The product to be treated is introduced into an enclosure whose walls are heated to a temperature preferably between 300 ° C. and 500 ° C., the walls being inclined so as to collect in a container a heavy fraction originating from polyethylene pyrolysis, while the light fraction, which volatilizes, is burned. The process is carried out in an oven which contains a series of trays, and in which a heating gas circulates. The upper surface of the oven has the shape of an inverted cone, with an orifice at the point through which its axis passes. The heavy fraction of the pyrolysis flows through it and is collected separately from the aluminum.

Document US 2003/0129077 A1 discloses an aluminum-based alloy for the production of foundry alloys with magnesium as the main alloying element, which contains at least 50% of scrap on

B E2016 / 5672 based on primary aluminum and as remaining primary aluminum and / or scrap on the basis of secondary aluminum of known composition. For the production of the aluminum-based alloy, mainly food and animal food packaging is used, separated by a pyrolysis process and then the aluminum contained in the packaging is recycled by fusion. The foundry alloys obtained from the aluminum-based alloy are particularly suitable for the manufacture of parts resistant to heat and / or corrosion in engines, in particular for the production of engine blocks, cylinder heads and of oil sumps, by means of sand casting, tempered casting, pressure casting, thixomolding or thixoforging.

Document US 2008/0264596 A1 discloses a process for the recycling of composite materials comprising the steps consisting in bringing a quantity of composite material composed of at least one polymer and of aluminum into at least one first reactor; heating the composite material in a non-oxidizing environment to a temperature sufficient to vaporize the polymer and form a hydrocarbon by-product and aluminum in the first reactor; feeding aluminum separated from the polymer to a second reactor; and heating the aluminum in a non-oxidizing environment to a temperature sufficient to melt the aluminum in the second reactor.

Document WO 2011/032696 A1 relates to a process for recycling aluminum from beverage cans, in which the beverage cans are ground into small particles in a grinder and the particles are first cleaned of residues beverage adherents and then cleaned of adherent paint residue. The first cleaning step is a spinning step in a centrifuge. The second downstream cleaning step is a thermal step of burning in an oven. Finally, the thermally cleaned particles are melted in a melting tank.

Document EP 0 442 027 A2 discloses a method for recovering disposable packaging, in particular packaging containers in the form of a tray for long-distance catering, in which it is proposed to orient the containers, with the open side facing down,

B E2016 / 5672 successively above a cleaning shower directed from bottom to top and then under a cleaning shower directed from top to bottom, and then subjecting them to a compression of material by means of forces directed vertically and finally to a pressing operation, which takes place perpendicular to them, to further compress the material. In document EP 0 487 961 A2, a method and a device for implementing the method are described, where two pressing operations are successively envisaged for significant compaction of the non-reusable packaging material, the compressed material then being granulated .

Document DE 25 18 935 A1 discloses a process for recycling waste or aluminum shavings into a finished product, by compressing aluminum waste at room temperature into billets or blocks having a density of 1.8 -2.4 g / cm ³ , by heating the metal block to 350 550 ° C, compressing the heated metal block in a pressure vessel into a mass having a density> 2.4 g / cm ³ , while maintaining a state in which the air pressure applied at the perimeter of the metal block is lower than that applied in its center, by continuously extruding the compacted metal block twice from the pressure vessel in a mold, while retaining the conditions described. Non-porous, dense, scab-free products are obtained, even using a small press, and with reduced energy consumption.

AIMS OF THE INVENTION The present invention aims to provide a solution for the effective recycling of all types and categories of aluminum packaging products (foils, cans, trays, capsules of tea and / or coffee, ... ), but also in the form of a mixture with machining chips, crushed waste or various aluminum fragments or parts, such as waste electrical equipment, and their recovery as new additives with high aluminum content (in the 1xxx series for example) and alternatively as aluminum products containing zinc, silicon and / or magnesium and other metals (manganese, ...).

B E2016 / 5672 The present invention also aims to propose a new manufacturing cycle with high ecological value, completely aligned with the concept of circular economy, the principle of which is essentially that of a loop economy succeeding in not to produce waste, or in any case a bare minimum, and to reduce any waste, in particular of materials or energy.

Summary of the invention The present invention relates to a process for manufacturing aluminum-based products based on an assembly step, that is to say a controlled mixture, or blend, of different types of recycled aluminum products and on at least the combination of the following processing steps:

- selective collection of recycled aluminum products from packaging, machining chips or in the form of crushed parts or fragments;

- assembly and production of a mixture of recycled products collected in given proportions according to their nature, the manufacturing route selected and the intended use;

- grinding and screening the mixture to give a finely divided product;

- compacting the product finely divided into briquettes, billets or blocks; and if necessary for final recovery,

- controlled fusion of briquettes;

- final nuance;

- casting and shaping into titrated ingots or granules according to customer demand and / or the intended use.

According to preferred or exemplary embodiments, the method further comprises at least one of the following characteristics or an adequate combination of these:

- the aluminum packaging collected is flexible, in the form of flexible sheets, co-laminated or not with sheets of paper and / or plastic, or rigid / semi-rigid in the form of beverage cans,

B E2016 / 5672 destination of food container, small trays or capsules of coffee and / or tea;

- the mixing is carried out according to the following proportions:

- flexible packaging: 5 to 50%,

- rigid / semi-rigid packaging: 5 to 50%,

- chips, parts and fragments: 5 to 100%;

- the components of the mixture undergo any possible oil removal;

- The product resulting from grinding and screening has a particle size between a few millimeters to a few centimeters;

- the compaction pressure is 300 bar maximum on an area of 10 to 50 cm ² ;

- the size of the briquettes is approximately 10 to 50 cm ² base on a height of 3 to 20 cm;

- the final shade includes an addition of other recycled aluminum products, in particular in the 2000 to 7000 series, and / or alloys;

- compacting into briquettes is followed by direct recovery of the briquettes, preferably in the absence of organic products in the basic recycled products or in the presence of such products whose content is below a certain predetermined threshold, this threshold being preferably between 0.1 to 1.5% organic;

- the briquettes have a density between 0.5 and 2.5 kg / dm ³ ;

the compacting into briquettes is followed by a controlled melting of the briquettes in a rotary kiln, preferably during the presence in recycled basic products of organic products the content of which is above a certain predetermined threshold, this threshold being preferably 0.5% organic;

- controlled melting is carried out in two stages, a pyrolysis pre-stage between 80 and 250 ° C, followed by a melting step between 650 and 860 ° C;

- The molten bath undergoes additional stirring, by variable rotation of the rotary kiln and continuously followed by gases and fumes;

- controlled melting is carried out with or without salt, in batch or continuously, including feeding the oven, with the application of a suitable burner,

B E2016 / 5672 preferably regenerative, and with a post-combustion of gases for the elimination of organics and finally with dynamic control;

- the dynamic control of the controlled fusion includes a gas analysis, a torque measurement and / or a LIBS measurement.

Brief Description of the Figures [0029] Figure 1 schematically shows an example of an embodiment of recycling / recovery treatment according to the present invention.

Description of a preferred embodiment of the invention The present invention relates to a manufacturing cycle based on one. assembly step, that is to say a controlled mixture ("blend"), of different types of recycled / recyclable aluminum products and on at least the combination of the following processing steps:

- selective collection of recycled aluminum products from packaging, for example foil types, cans, trays, tea and / or coffee capsules, shavings, waste and various fragments, ...;

- assembly and production of mixtures of recycled products collected in given proportions according to their nature, the selected manufacturing route (see below) and the intended use / final recovery:

- flexible packaging: 5 to 50%,

- rigid / semi-rigid packaging: 5 to 50%,

- chips, waste and various fragments: 5 to 100%;

- grinding of these mixtures until a particle size ranging from a few millimeters to a few centimeters is obtained;

- compacting into briquettes, for example of the following dimensions: 21.8 cm ² base x 3 to 8 cm high, with a pressure of 300 bar maximum, and if necessary for final recovery;

- controlled merger;

B E2016 / 5672

- final shading, and in particular for additions to metal coating baths, with the incorporation of other recycled aluminum products (for example from classes 2000 to 7000) and / or alloys;

- casting and shaping of titrated ingots or granules according to the customer's request and / or the desired end use.

The proportions of recycled products are given by weight and the sum of the proportions indicated is 100%.

According to a first preferred embodiment, the compacting into briquettes is followed by a first direct recovery of the briquettes, preferably in the absence of organic products in harmful quantities (paints, varnishes, food residues, ... ) or being at most of the order of 0.1 to 1.5%. The density should be checked, preferably between 0.5 and 2.5 g / cm ³ . According to a second preferred embodiment, the compacting into briquettes is followed by a melting of the briquettes in a rotary kiln for mixtures with organics (> 0.5%).

According to a preferred embodiment, the controlled fusion is carried out in two stages with pyrolysis pre-stage, according to a first phase with a temperature ranging from 80 to 250 ° C. and a second fusion phase with a temperature, ranging from 650 to 856 ° C.

Preferably, the controlled fusion will be carried out:

- with or without salt;

- batch or continuous (including supply to the oven);

- with the application of a suitable burner, possibly regenerative and post-combustion of the gases;

- with dynamic control such as: gas analysis, torque measurement, LIBS, etc.

EXAMPLE Figure 1 gives an example of a recycling / recovery treatment process for recycled aluminum waste.

We first collect different types of aluminum or aluminum recyclable products: light 11 and rigid packaging 12, long machining chips 13 (oily or not), short dry chips 14

BE2016 / 5672 (non-oily), waste electrical and electronic equipment (WEEE) 15, various fragments 16, etc.

We proceed to a mixture 1 of these products in proportions to be defined optionally depending on the target final product (composition, etc.).

Grinding and screening 2 of the mixture is carried out until a product having a particle size ranging from a few millimeters to a few centimeters is obtained. Any massive objects 21 that cannot be shredded are eliminated at this stage.

We then proceed to compaction 3 of this product of 10 controlled particle size, possibly adding short oily shavings 31, to obtain briquettes 33 and a crop of cutting oil

32. In the notable absence of organic products, the briquettes are valued directly, therefore with a fusion bypass 4, followed by final shaping into ingots, bars, granules, etc. of appropriate dimensions 61.

In the presence of organic products, alternatively, a controlled fusion 5 is carried out, with or without salt. The organic materials are eliminated by pyrolysis and post-combustion 51. A casting / solidification 6 is carried out to obtain the final product titrated 61 in suitable form (ingots, bars, granules, truncated cones, flats, etc.).

List of reference symbols

1 mixed 2 grinding 3 compaction 4 fusion bypass 5 fusion with or without salt 6 casting / solidification 11 flexible packaging 12 rigid packaging 13 long shavings (oily or not) 14 short dry shavings

B E2016 / 5672

15 WEEE 16 fragments 21 massive objects 31 short shavings (oily) 32 cutting oil 33 briquettes 51 pyrolysis and post-combustion of organic matter 52 aluminum ingots in the desired formats 61 ingots, bars, granules, truncated cones, flats, etc.

BE2016 / 5672

Claims (15)

1. Method for manufacturing aluminum-based products based on an assembly step, ie a controlled mixture, or blend, of different types of recycled aluminum products and on at least the combination of steps following treatment: - selective collection of recycled aluminum products from packaging, machining chips, waste electrical / electronic equipment and / or in the form of crushed parts or fragments (11,12,13, 14,15,16) ; - assembly and production of a mixture (1) of recycled products collected in given proportions according to their nature, the selected manufacturing route and the intended use; - grinding and screening (2) of the mixture to give a finely divided product; - compacting (3) of the product finely divided into briquettes, billets or blocks (33), and if necessary for the final recovery; - controlled melting (5) of the briquettes (33); - final nuance; - casting and / or shaping (6) into titrated ingots or granules (52, 61) depending on the customer's request and / or the intended use. 2. Method according to claim 1, characterized in that the aluminum packaging collected is flexible (11), in the form of flexible sheets, co-laminated or not with sheets of paper and / or plastic, or rigid / semi-rigid (12) in the form of beverage cans, trays for food containers, small trays or capsules of coffee and / or tea. 3. Method according to claim 2, characterized in that the mixing is carried out in the following proportions: - flexible packaging (11): 5 to 50%, - rigid / semi-rigid packaging (12): 5 to 50%, - chips, parts and fragments (13, 14, 15, 16, 31): 5 to 100%. BE2016 / 5672 4. Method according to claim 1, characterized in that the components of the mixture (1) undergo any possible oil removal. 5. Method according to claim 1, characterized in that the product resulting from grinding and screening (2) has a particle size included 5 between a few millimeters to a few centimeters. 6. Method according to claim 1, characterized in that the compaction pressure (3) is 300 bar maximum on an area of 10 to 50 cm ² . 7. Method according to claim 1, characterized in that the size 10 of the briquettes (33) is 10 to 50 cm ² base on a height of 3 to 20 cm. 8. Method according to claim 1, characterized in that the final shading comprises an addition of other recycled aluminum products, especially in the 2000 to 7000 series, and / or alloys. 9. Method according to claim 1, characterized in that the compacting into briquettes is followed by a direct recovery of the briquettes (33), preferably in the absence of organic products in the basic recycled products or in the presence of such products whose content is below a certain predetermined threshold, this threshold preferably being between 0.1 to 1.5% organic. 20 10. Method according to claim 9, characterized in that the briquettes (33) have a density between 0.5 and 2.5 g / cm ³ . 11. Method according to claim 1, characterized in that the compacting (3) into briquettes is followed by a controlled melting (5) of the briquettes in a rotary kiln, preferably during the presence in recycled products of 25 based on organic products the content of which is above a certain predetermined threshold, this threshold preferably being 0.5% organic. 12. Method according to claim 11, characterized in that the controlled melting (5) is carried out in two stages, a pyrolysis pre-stage between 80 and 250 ° C, followed by a proper melting stage between 650 and 860 ° C. B E2016 / 5672 13. The method of claim 11, characterized in that the molten bath (5) undergoes additional stirring, by variable rotation of the rotary kiln and followed, continuously, gases and fumes. 14. Method according to claim 11, characterized in that the controlled fusion (5) is carried out with or without salt, in batch or continuously including the supply of the oven, with the application of a suitable burner, preferably regenerative, and with a post-combustion of gases for the elimination of organics and finally with dynamic control. 15. Method according to claim 14, characterized in that the dynamic control of the controlled fusion comprises an analysis of the gases, a measurement of torque and / or a LIBS measurement. BE2016 / 5672 17