MXPA99008163A - Method and device for melting and refining materials capable of being vitrified - Google Patents

Abstract

The invention concerns a method for melting and refining materials capable of being vitrified, such that all or part of the heat energy required for melting said materials capable of being vitrified is supplied by burning fossil fuel(s) with at least an oxidant gas, said fuel(s)/gas(es) or gas products derived from combustion being injected beneath the mass of materials capable of being vitrified (7). The refining of the melted materials capable of being vitrified comprises at least a step of pressurisation at sub-atmospheric pressure level. The invention also concerns the device for implementing the method and its applications.

Description

PROCEDURE AND DEVICE FOR FUSING AND TUNING VITRIFICABLE MATERIALS DESCRIPTION The present invention relates to a melting and refining process of vitrifiable materials for feeding with continuous molten glass, glass forming installations. The flat glass formation installations as well as the float laminate installations are more particularly the object of the present invention, but so are the hollow glass forming installations of the bottles, knobs, glass fibers of the mineral wool type of thermal or phonic insulation or also the textile glass yarns called reinforcement. Many of the search works were related to those procedures that schematically comprise a first melting stage, followed by a tuning intended to thermally and chemically condition the molten glass, and to suppress the non-melted parts, the bubbles, all this causing defects that appear after the training.

For example, in the field of fusion, it has also sought to accelerate the merger, or improve energy efficiency. In this way, one can mention the procedure that consists of rapidly heating, in a homogeneous and controlled manner, the vitrifiable materials, carrying out an intense mechanical mixing that allows to put intimately in contact, the vitrifiable materials still solid with the already liquid phase. This method is particularly detailed in the patents: FR-2 423 452, FR-2 281 902, FR-2 340 911, FR-2 551 746, and generally uses electrical heating means of the submerged electrodes type. Another type of fusion process was developed, for example of the type of those described in the patents US-3 627 504, US-3 260 587 or US-4 539 034 which consist in using as heating means, submerged burners , ie gas and air-fed burners, generally arranged so as to reach the level of the hearth so that the flame develops within the mass of the vitrifiable materials in the course of liquefaction. In one case as in the other, if it is effectively prevented to reduce very significantly the residence time of the vitrifiable materials in the melting chamber, in considerably increasing the yield of production in relation to "classical" mergers, on the contrary, the glass in fusion it is presented in the form of a foam that is delicate to refine; above all it is difficult to guarantee the same quality to the final glass, especially optical. Searches were also made in the field of tuning. Thus, it is known, for example, from patent EP-775 671 and US-4 919 697 to perform at least a part of the tuning under reduced pressure, which allowed, for example, obtaining glasses containing very few sulfates, and strong redox. However, a tuning of this type causes intense foaming, which can be delicate to control and eliminate. The object of the invention is therefore to improve the melting and tuning processes, especially with the aim of using more compact and / or more flexible installations in their operation and / or more important production performance, etc ..., without these industrial advantages being obtained to the detriment of the quality of the glass produced. First, the invention has as its object a melting and refining process for vitrifiable materials which is characterized by the combination of two characteristics: on the one hand, all or part of the thermal energy necessary for the melting of the vitrifiable materials is provided by combustion of fossil fuel (s) with at least one fuel gas; those fuels / gas or gaseous products that come from combustion, are injected below the level of the mass of the vitrifiable materials; - on the other hand, the refining of vitrifiable materials after the merger, comprises at least one step of putting into operation at a subatmospheric pressure. It was revealed that there was in fact an extremely advantageous synergy on the industrial plane between the use of a so-called "submerged burner" fusion, for simplicity and that of a tuning under reduced pressure. However, this combination was far from being imposed as evidence, and it could be expected that all those advantages detailed below will be obtained only at the price of mediocre glass quality, which was not the case. In fact, if the principle of a tuning under reduced pressure was known in its generality, it was delicate to use it, and it was not sure to obtain the residual rate in bubbles / parts without melting only with a classical tuning. On the other hand, in the invention, that very particular tuning is used, changing a size parameter, namely: that instead of feeding the tuning area with "classic" molten glass to be tuned, it is actually fed here with a glass that is obtained by fusion by means of submerged burners, that is to say with glass of totally particular characteristics in the sense that it is globally foamy, with a relatively small density in relation to that of a normal glass. Nothing left one to suppose that it could be tuned at reduced pressure, a relatively sparkling glass of departure. Surprisingly, this became clear that it was possible, because it has been discovered that this sparkling glass, which comes from a fusion by means of submerged burners, also had the characteristic of containing only and extremely few sulfates, whether or not one has the same, starting. In general, there is less than 600 and even less than 200 or less than 100 ppm, even less than 50 ppm of sulphate expressed by weight of S02, in the glass that leaves the melting chamber, and this without having to control , to reduce the sulphate rate customarily contained by the raw materials used, inadvertently, even by voluntarily adding sulfates to the vitrifiable materials. And it's that small sulfate rate that allows you to fine tune under reduced pressure without problem. In the opposite case, a percentage of important or simply "normal" content of sulphate in the glass to be refined, would have caused at the time of the tuning at reduced pressure, a very strong expansion of the foam by desulfation, expansion that would have been totally delicate to control and to dominate. This almost absence of sulphate in the glass at the exit of the fusion chamber, can be explained above all by the partial pressure of water generated by the combustion of the submerged burners within the vitrifiable materials. It should be noted that a desulfated glass, gives less problems of volatile compounds in the bath fl oa t, less risk of formation of tin sulfide and therefore, in the end, less risk of tin defect on the glass sheet. This decreases the amount of sulfides (even totally suppresses it) in the case of reduced glasses, especially of iron sulphides that give unwanted yellow / amber residual colors or inclusions of nickel sulphide, which can cause the breaking of the glass at the moment of thermal treatments of the tempered type. Another very advantageous feature of the glass at the outlet of the melting chamber according to the invention should also be noted: if it is effectively in the form of a type of foam that remains to be refined, the size of the bubbles it contains can be controlled, and all in certain cases, almost eliminate all the smallest bubbles, that is to say with a diameter of 200 μm, effecting on that glass at the time of its fusion, a type of "micro-tuning" prior to the true tuning that follows the fusion; micro-tuning that facilitates the coalescence of the bubbles, the disappearance of the smallest bubbles for the benefit of the larger ones and favors by means of addition in. the vitrifiable substances of coking aids or sulfates. In addition, that glass at the outlet of the melting chamber generally has a particularly small residual rate of unmelted parts, which here too, such as the size of the bubbles, facilitates the tuning operation that follows the melting. Therefore the invention allows to have glasses with very few sulfates before the tuning operation, therefore of glasses at least with less sulphates, or even more with few sulfates after tuning, and this without having to purify / select vitrifiable materials so that they have little sulphate. On the contrary, you can still add starting sulphate, which is totally amazing and advantageous.

An advantageous effect obtained by the combination according to the invention is related to the energy cost of the process: the fusion by submerged burners allows to have no recourse to the electric fusion of the submerged electrodes type, whose cost can be very significant according to the countries . In addition, and this is the most important point, the fusion by submerged burners creates a convective mixing within the vitrifiable materials in the course of liquefaction, as detailed below. This very strong mixture between materials still not liquefied and those that are already in fusion, is extremely effective, and allows to obtain a fusion of vitrifiable materials of identical chemical composition, at a lower temperature and / or much faster than with heating means traditional And tuning under reduced pressure also makes it possible to refine the glass at a lower temperature, and much more quickly. In fact, by lowering the pressure at the time of tuning, an increase in the molar volume of the gases contained in the meltable vitrifiable materials is caused, of which an increase in the volume of the bubbles that it contains and consequently an increase of its ascension velocities towards the surface of the bath and its evacuation.

By tweaking the reduced pressure, you can "afford" to work at the lowest temperature compared to the classic tunings, just inside the lower temperatures that are used with the technique of fusion by submerged burners. Therefore, the temperatures found at the same time in the melting and tuning according to the invention, are fully compatible and adapted to each other, and globally less elevated compared with the usual procedures, which is very interesting economically speaking, simply in terms of energy cost, but also because of the selection of materials of the refractory type that then enter the manufacturing of the facilities: less hot, they corrode less quickly. The times of permanence in the fusion zone and in that of the tuning, are also very significantly reduced and compatible, which is obviously very positive on the production yield, on the removal of the installation as a whole. At the same time, the invention makes it possible to obtain very compact installations: in fact, the fusion by submerged burners, always thanks to the very strong mixing that it causes, allows to considerably reduce the size of the melting chamber. And the tuning under reduced pressure has the same consequences on the size of the compartment (s) where this operation is carried out: globally, the installation can be very compact therefore, with clear gains in terms of construction cost, simplification of operation, reduction of wear of construction materials, etc ... In what relates to the operation of fusion, the selected comburent can be, according to the invention, based on air, air enriched with oxygen or even substantially based on oxygen. A strong oxygen concentration in the oxidizer is effectively advantageous due to different reasons: combustion fumes are diminished, which is favorable on the energy plan and in which it avoids any risk of excessive fluidization of the vitrifiable materials that can cause projections on the superstructures, vaults of the fusion chamber. In addition, the "flames" that are obtained are shorter, more emissive, which allows a rapid transfer of energy to vitrifiable materials, and incidentally decrease, if desired, the depth of the "bath" of vitrifiable materials in the course of liquefaction. It starts here with "flames", but they are not necessarily flames in the usual sense of the term. It is possible to speak more generally - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - further, any eventual NO gas emission, contaminant, is reduced in that way to the minimum. Regarding the selection of the fuel, this can be of the gaseous fossil fuel type or not, such as natural gas, propane, fuel or any other hydrocarbon fuel. It can be hydrogen. The melting process by submerged burners according to the invention is then an advantageous means of using hydrogen, on the other hand difficult to use with "aerial" burners, not submerged, since the low emissive character of the flames obtained by combustion between H2 and O2 • Combining in a fusion by submerged burners, the use of an oxygen comburent and that of a hydrogen fuel, is a good means of ensuring an efficient thermal transfer of the energy from the burners to the molten glass, which otherwise leads to a completely "own" procedure, that is without NO nitrogen oxide emission, or greenhouse gas of the CO type? that is not the one that may come from the decarbonisation of raw materials. Advantageously, the melting is carried out according to the invention in at least one melting chamber which is equipped with burners arranged in such a way that their combustion or combustion gas develops in the mass of the vitrifiable materials during the melting process. In this way, they can be traversed through their side walls, the floor and / or suspended above, by hooking them to the vault or any appropriate superstructure. These burners can be such that their gas arrival pipes reach the level of the wall they pass through. It may be preferable that these conduits "enter", at least in part, into the mass of the vitrifiable materials, in order to prevent the flames from being too close to the walls, and cause premature wear of the refractory materials. You can also select to inject only the combustion gases; the combustions are made outside the fusion chamber itself. As mentioned above, it was revealed that this heating mode caused, by convection, an intense mixing of the vitrifiable materials: a half circles of convection are formed in this way on one side and on the other of the combustions or " flames "or combustion gas streams, permanently mixing the molten materials and those not yet melted in a very effective manner. In this way, the favorable characteristics of a "stirred" fusion are again found, without resorting to unreliable mechanical agitation means and / or that wear out quickly. Preferably, the height of the mass of the vitrifiable materials in the melting chamber is regulated, as well as the one on which combustion or combustion gases develop, so that these combustions / gases remain in the mass of these materials vitrifiable: the object is that of allowing to establish in this way the circles of convective circulation in matter in the course of liquefaction. In general, this type of fusion allows to reduce considerably the emission of any type of powder at the level of the fusion chamber, and of NO? , because the thermal exchanges are made very quickly, avoiding the peaks of temperatures that can favor the formation of these gases. It also reduces in a considerable way, the emission of CO type gases? . Optionally, it can be foreseen to precede the melting by a stage of preheating of the vitrifiable materials, at a temperature nevertheless significantly lower, than that which is necessary to liquefy them, for example at more than 900 ° C. To perform this preheating, the thermal energy of the fumes can be advantageously recovered. By impoverishing them in this way thermally, the specific energy consumption of the installation can be reduced overall. The vitrifiable materials may comprise raw materials, but also pulverized glass, even waste destined to be vitrified. They can also comprise fuel elements (organic): in this way they can be recirculated, for example, mineral fibers ensimadas, with a binder (of the type of those used in thermal or acoustic insulation or those used to reinforce materials plastic), glazing sheets with polymer sheets of the polyvinyl butyral type, such as para-breezes, or any type of "composite" material associating glass and plastic materials, such as certain bottles. In this way, it is also possible to recirculate "glass-metal compounds or metal compounds", such as glazing functionalized with coatings containing metals, difficult to recirculate up to now, because this had the risk of causing a progressive enrichment of the melting chamber in metals that accumulate on the surface of the hearth. However, the mixing imposed by the fusion according to the invention makes it possible to avoid this sedimentation and, for example, to recirculate enamel coated with enamel layers, with metal layers and / or with different connection elements. The object of the invention is also to recirculate all those composite elements that contain glass thanks to the fusion by burners submerged in a glass oven. Above all, furnaces with submerged burners can be provided, the essential function of which is that of the manufacture of a pulverized glass from those diverse materials that are to be recirculated, particularly pulverized glass that can then serve as raw materials, associated or not with the normal powdered glass, for traditional glass kilns. Advantageously, it is possible to provide all or part of the vitrifiable materials in the melting chamber below the level of the mass of the vitrifiable materials during the melting process. You can enter a part of those subjects in a customary way, above the mass in the course of liquefaction, and the rest below, for example by means of bringing the screw type endless. In this way, materials can be introduced directly into the mass in the course of liquefaction, in a single point or at different points distributed in the walls of the fusion chamber. Such an introduction, directly into the mass of materials in the course of liquefaction (hereinafter referred to by "glass bath") is advantageous for more than one reason: first, any risk of volatile release of raw materials is considerably reduced. above the glass bath; therefore it minimizes the rate of solid powders emitted by the furnace. Then, it allows to better control the minimum dwell time of these materials before extraction to the tuning area, and selectively introduce them where the convective mixing is stronger, according to the arrangement of the submerged burners. That or those points of introduction in the glass bath can (can) be found in that way in the vicinity of the surface, or more deeply in the glass bath, for example at a height of glass bath, comprised between 2/5 parts and 4/5 parts of the total depth of the glass bath, from the floor level, or also between 1/3 part and 2/3 parts of that depth. It has been found that the process according to the invention allowed to recycle plastic materials, in the form of composite products associated with glass; very particularly, those plastics serve in that way as part of fuel. It is also possible and advantageous to introduce all or part of the fuel necessary for melting by submerged burners in the form of solid fuel (organic materials of polymer type, coal) or even liquid fuel; that fuel comes to replace in part at least the fuels (especially fossil) liquid or gas that feed the burners. In general, the term "vitrifiable materials" or "raw materials" used in this text, is intended to cover the materials necessary to obtain a glassy matrix (or ceramic or vitro-ceramic), but also all additives (tuning additives, etc ...), all possible liquid or solid fuels (plastic or composite material or not, organic materials, coal, etc ...), all types of powdered glass. The process according to the invention can operate at a high pulverized glass rate. As mentioned above, the tuning according to the invention is therefore carried out on meltable vitrifiable materials of the type in the foamed state. Typically, this foam has a density of about 1 to 2, ie a density of 1 to 2 g / cm 3 (to be compared to a density of the order of 2.4 for non-foaming glass), preferably a sulphate at most 600 or even more than 100 ppm expressed by weight of S03 and a majority of bubbles with a diameter of at least 200 μm. In this way, it can have a volumetric mass comprised between 0.5 and 2 g / cm3, especially 1 to 2 g / cm. To improve the tuning behavior, various refining aid additives are preferably added to the vitrifiable materials. The object was above all to make disappear of the glass, the bubbles of smaller diameter to 200 μm from the fusion stage, as it is evoked above. They can be reducing additives, such as coke (which also allows adjusting the redox of the glass). In this case, it is advantageous to select coke powder with an average grain size of less than 200 μm. It can also be sulfates. The tuning under reduced pressure, causes a growth of the bubbles; the object is that this growth is done quickly, and that bubbles can easily be evacuated or burst on the surface of the glass bath. Other tuning aid additives will be rather effective at the time of the tuning stage, properly speaking, after that of the merger. They allow, above all, to "destabilize" the foam: it is, for example, fluorine or a compound of fluorine or chlorine, more generally of halides, or also of nitrate of the NaN03 type; fluorine (halogen) seems to lower the viscosity of the glass; in that way it would facilitate the draining of the films that are formed between the bubbles, draining that favors the fall of the foam. It also lowers the surface tension of the glass. Another factor that influences the manner in which the growth of the bubbles takes place at the time of tuning under reduced pressure, is the nature of the gases above the material in fusion. Of course, you can simply select a partial air pressure. It can also be selected to enrich the atmosphere with inert gas of the nitrogen type, even if a partial pressure is not selected only with inert gas of the nitrogen type. Indeed, it was noted that selecting a residual pressure of inert gas of the nitrogen type was favorable to the bursting of the bubbles on the surface at the time of tuning. In fact, it is the too strong concentration of oxidizing gas of type 02 that seems unfavorably to tend to stop this explosion. Advantageously, the sub-atmospheric pressure in which at least a part of the tuning is effected is less than or equal to 0.5 atmosphere (0.5.105 Pa), especially in the order of 0.3 to 0.01 atmosphere (approximately 3.104 to 0.1.103). Pa). Advantageously, the method according to the invention allows melting and / or tuning to be carried out at temperatures not exceeding 1400 ° C, especially at most 1380 ° C or 1350 ° C. The tuning according to the invention, according to a first variant, can be done in at least one static compartment (motionless in operation) in front of the melting chamber and of which at least one area is put under reduced pressure. According to a second variant, the tuning is always operated in front of the fusion chamber, but in a compartment that can be rotated to ensure tuning by centrifugation, with at least one area of that compartment above all further back, which it is put under reduced pressure. A third variant consists of combining the two above, especially using for the tuning a first static compartment with a zone under reduced pressure, and then a second compartment in rotation also comprising a zone under reduced pressure, preferably more reduced than in the static compartment. According to one embodiment, the method according to the invention provides for treating the flow of the meltable vitrifiable materials, between the melting phase and the tuning phase or at the beginning of the tuning phase, with at least one jet dividing means. This means, for example a perforated element with orifices by which the flowing glass flow is forced to pass, allows that flow to be divided into a large number of small diameter threads. The size of the holes is advantageously selected so as to be close to that of the bubbles to be eliminated. In this way, if the jet divider means is arranged just after the sub-atmospheric pressure zone of the tuning compartment, the action of the reduced pressure will be exerted very quickly on the trickles generated by the jet divider means, and allow fast tuning, even at important glass flows. The feeding of glass to be refined from the tuning compartment can thus become more or less analogous to that obtained by means of a row that would lead to a room of reduced pressure. (In the context of the invention, the terms "back" and "forward" refer to the direction of the runoff or flow of the glass in the installation, from the placing of the vitrifiable materials in the melting chamber, to the extraction of the glass tuned up). The melting / tuning process according to the invention makes it possible to produce glasses of very varied compositions and properties. Due to the fact of its low inertia, it allows, on the other hand, to move from one composition to another, with very short transition times. In this way, it allows to manufacture relatively small glasses, which have a redox above or equal to 0.3 (redox is defined as the ratio of the percentage content by weight of ferrous iron FeO to the percentage of total iron content of the composition expressed under the form of Fe203). It also makes it possible to manufacture glasses with a high Si02 rate, for example at least 72% or even at least 75% by weight, glass generally difficult to melt, but interesting, especially in terms of cost of raw materials, due to the fact that they are of low density, and that they have a very good compatibility with plastic materials. It also makes it possible to manufacture quite particular glasses, with a high rate of alkaline-earth oxide, for example containing at least 18% by weight of CaO, however quite corrosive with traditional melting processes at a higher temperature than that according to the invention , as well as glasses of small sodium oxide, of at least 11% by weight for example, or at small sulphate rates, at most 100 ppm for example. Glasses containing iron, high redox but small percentage of sulfate content, also allow the obtaining of residual color glasses in blue, particularly aesthetic and sought in the field of flat glass for the automobile and for construction for example. In this way, very selective antisun glasses can be obtained, on which anti-solar layers can be deposited to reinforce the thermal behaviors, of the TiN type for example, layers that are described in the patents: EP-638 627 and EP-511 901. The subject of the invention is also a melting and tuning device, especially adapted for the work described above, comprising: - at least one melting chamber equipped with burners supplied with fuel (s); ) fossil (s) of the type gas (natural) and of oxidizer (s) of the air or oxygen type; these burners are arranged so as to inject those gases or the gases that come from the combustion, below the level of the mass of the vitrifiable materials introduced in that fusion chamber; - at least one tuning compartment in front of the melting chamber and comprising at least one area that can be put under sub-atmospheric pressure. Advantageously, as mentioned above, the melting chamber can be equipped with at least one means for introducing vitrifiable materials below the level of the glass bath, especially at least two and preferably in the form of an opening (s). in the walls associated (s) to a conveyor means of the worm type. In this way, the risks of volatile release of the powders are minimized, while at the same time preventing an introduction above the glass bath for vitrifiable materials such as silica, on which a preheating operation can be carried out without risk. of mass taking.

Independently of the tuning operation also, the invention also relates to the concept improvements concerning the walls of the melting chamber which are intended to be brought into contact with the glass bath. Several variants are possible. In certain cases, known refractory materials based on oxide such as alumina, chromium oxide, refractories called AZS (based on alumina, zirconium and silica) can be used. It is generally preferred to associate them with a water circulation cooling system of the water type ("wa ter jacke t" or cooling by water box in Spanish). Provision can be made for arranging the water box on the outside; the refractories are then in direct contact with the glass, on the inside. The function of the water box is therefore to create a vein of colder glass in the vicinity of the refractories, particularly requested in this context because the glass bath generated by the submerged burners causes strong convective currents against the walls. Another variant consists of not using refractories in the area of the glass bath, but only the box mentioned above. Another variant consists of using refractory materials (possibly associated with a cooling system of the water box type) and of lining them with a coating of a highly refractory metal such as molybdenum (or Mo alloy). This coating can advantageously be maintained at a distance (for example from 1 to a few millimeters) from the walls of the refractories, and offer the glass bath a continuous contact surface [plate (s) filled with Mo] or not, [perforated plate (s) with Mo holes). This coating has the purpose of mechanically avoiding a direct convection of the glass on the refractories, generating a layer of "calm" glass along the refractories even suppressing any contact of the glass with the latter. In the melting chamber, preferably all or part of the burners have been submerged so that they can inject into the glass bath a fluid that does not participate in the combustion, in substitution (temporary) to the oxidizer and / or to the fuel. This fluid can be an inert gas of the N2 type or a cooling fluid of the liquid water type that vaporizes immediately in the glass bath. The fact of stopping the combustion temporarily while continuing to inject a fluid at the level of the burner, generally has two objectives: either that one wishes to stop the operation of the burner and more generally for example of the fusion chamber as a whole; the injection of inert gas of the N2 type allows to ensure the chamber at the level of the burners; Whether you want to change the burner for another, then the other burners work and therefore you are always in the presence of a molten glass bath. In this case, as indicated in detail below, appropriately projecting water through the burner allows the glass to be temporarily set above the burner, creating a kind of "bell", which leaves enough time for proceed to the change without envirriar the burner. As mentioned above, it can be envisaged to provide the device according to the invention with at least one jet dividing means between the melting chamber and the tuning compartment, especially just at the entrance to the tuning compartment or its part further back. It can be a perforated element with holes of appropriate size. On the other hand it should be noted that the use of a jet divider can also be planned independently of the adapted mode of fusion: such a divider means that it can be tuned more quickly, with important glass flows, whatever the manner in which it is used. it has obtained the fusion of the glass, for example by conventional means of the type of aerial burners (not submerged) and / or by electric fusion by means of submerged electrodes. In the same way, it can be interesting to use it even if the tuning is carried out at atmospheric pressure.

However, it is particularly interesting to employ it in a melting context by submerged burners which tends to generate a foam with very high bubble rate, and / or in a tuning context under reduced pressure, because it considerably increases the efficiency which is already particularly elevated According to a first variant mentioned above, the tuning compartment is static and in elevation (that is, of a height significantly greater than its dimensions on the ground). This compartment comprises, according to a first embodiment, a practically vertical internal separation delimiting, in combination with the internal walls of the compartment, at least two channels. It is successively a first channel that imposes to the vitrifiable materials in fusion, an ascending trajectory and then a second channel that imposes a downward trajectory on these vitrifiable materials; the first channel is preferably that which is placed at sub-atmospheric pressure. In this way a type of siphon is created for the glass that is going to be refined. This compartment is advantageously equipped with means for regulating / controlling the loss of charge of the meltable vitrifiable materials at the entrance to the tuning compartment. In the same way, it is planned to adjust the height of the tuning compartment according to different criteria, especially depending on the level of depression selected in the area under reduced pressure. According to a second embodiment, the static tuning compartment used in the context of the invention is in elevation, and comprises means for introducing meltable vitrifiable materials to be refined in the upper part, and means for evacuating materials tuned in the lower part; these subjects globally follow a mainly vertical descending trajectory in that compartment. Its concept can be inspired, for example, by the teachings of patents EP-231 518, EP-253 188, EP-257 238 and EP-297 405. According to a second variant, the tuning compartment comprises at least one apparatus that can be put into rotation to ensure the tuning by centrifugation; the internal walls of this apparatus virtually define the shape of a vertical hollow cylinder at least in its median part. Advantageously, the apparatus comprises a so-called upper sub-atmospheric pressure zone and a so-called lower zone which is left at ambient pressure, and which are separated one from the other, by one or more mechanical means of the perforated metal plate type with orifice ( s). According to a preferred concept, the apparatus is fed in its upper part with meltable vitrifiable materials, by a static conveying means of the drainage channel type. These bringing means may comprise at least one compartment which is placed under reduced pressure, to allow the feeding of the apparatus and / or to carry out a first tuning. It is necessary to provide sealing means which ensure the connection between the end of that channel with these means for bringing the apparatus, means of the type "dynamic joint" or rotary joint, as detailed below. The apparatus is advantageously provided with means for capturing solid particles of density greater than that of the glass, means which are located above all in its lower area and in the form of notches / grooves made in its internal walls. Preferably, the rotation speed of the apparatus is selected between 100 and 1500 turns per minute. The apparatus can also be provided with mechanical means fixed or following its rotation, and can crush the foam and carry it from top to bottom, that is to say towards the lower area of the apparatus from which the refined glass is taken. These means are mainly in the form of perforated deflectors, fins arranged in the upper area of the apparatus. That type of centrifugal tuning with passage inside a zone of reduced pressure, it is particularly effective. In effect, the reduced pressure will allow to ensure the strongest possible growth in the bubbles of the proper tuning by centrifugation: the bubbles are eliminated as soon as possible in the apparatus, as their diameter is important. The reduced pressure will also allow the percentage of residual sulphate content of the produced glass to decrease. It should be noted that a desulfated glass (this observation also applies to the first variant where the tuning is made in static form), gives less problems of volatile compounds in the bath fl oa t, less risk of sulfide formation and therefore to the final, less risk of lack of tin on the glass sheet. This also guarantees the absence of sulfides in the case of reduced glasses, especially of iron sulphides that give unwanted yellow / amber residual colors or inclusions of nickel sulphide, which can cause the glass to rupture at the time of thermal treatments of the type tempered. The centrifugal tuning comprising a phase of reduced pressure, is particularly indicated in the case of the tuning of the relatively foamed glass. The invention will be detailed below with the aid of two non-limiting embodiments, which are illustrated by means of the following figures: Figure 1: a schematic melting / tuning installation using a static tuning device; Figure 2: a schematic tuning fusion facility using a tuning device by centrifugation; Figure 3: an enlarged view of a tuning device of the installation of the type shown in Figure 2; Figure 4: a schematic enlarged view of the jet divider used in the device of Figure 2; Figure 5: a schematic cross-sectional view of a submerged burner that equips the fusion chamber of the installations of figures 1 and 2. These figures are not necessarily to scale and for clarity are extremely simplified. The devices described below are adapted to melt and refine glasses of very varied compositions; here glasses intended to feed a floa t installation to produce flat glass. But this application is not limiting. In addition, of course, all normal glasses of the silica-soda-calcium type, different types of special glasses, are particularly interesting to manufacture with the devices according to the invention, especially those that are considered to date as difficult to melt: glasses of small Na02 and relatively high rate of alkaline earth oxide, especially CaO, advantageous on the economic level in terms of cost of raw materials, but - quite corrosive at the conventional melting temperatures and relatively hard to melt by means of the classic procedures. These may be glass compositions, for example those described in patent FR-97/08261 lo. July 1997, such as (% by weight): SiO- from 72 to 74., 3 O A1203 from 0 'or to 1. .6% Na20 from 11.1 or,? to 13. .3"or? 2o from 0 g, or to 1.5. or, or CaO from 7.5% to 10 o.

MgO of 3.5% at 4. .5 o, O Fe2 ° 3 of 0.1 g. to 1% or also of compositions of the type (expressed in percentages by weight: YES- from 66% to 7 2% especially from 68% to 70% A1203 from 0% to 7 3- Fe 2 ° 3 from 0% to 1% CaO from 15% to 22% MgO, especially from 3% to 6% Na20 from 4% to 9%, especially from 5% to 6% - 2o from 0% to 2% especially from 0% to 1% SO-traces An example illustrating this family of compositions is the following: SiO- 69% Al2 ° 3 1% Fe2 ° 3 0.1% CaO 18.9% MgO2o 0.3% Na20 5.6% SO, trace This glass has a lower temperature of annealing called also strain poin t of 590 ° C (temperature at which the glass has a viscosity of 1014.5 poises). There is also a temperature of liquids of 1225 ° C, a temperature T (log2) of 1431 ° C and a temperature T (log3.5) of 1140 ° C [Tlog (2) and Tlog (3.5), correspond to temperatures that the glass has respectively when it reaches in poises, a viscosity of log2 or log3.5] glasses of strong silica rate, also interesting on the economic plane, and with a relatively small density, whose field of compositions, always expressed in percentages weight, is as follows: Si02 from 72% to 80 CaO + MgO + BaO from 0.3% to 14% Na20 from 11% to 17 alkaline oxides from 11% to 18. 3 ^ 515- A1203 from 0.2% to 2 o, c B 2 ° 3 from 0% to 2 o, 'Fe 2 ° 3 from 0% to 3 o, -or optionally traces coke from 0 to 600 ppm and eventually coloring oxides: Ni oxide, Cr, Co etc ... (These glasses have the peculiarity of being particularly viscous) An example that illustrates this family of compositions, is the following: sio2 76.4% Fe203 0.1% Al2 ° 3 0.1% cao 7.6% MgO 5% Na20 10% K2o There is a density of approximately 2.46 (compare with the densities of 2.52 of the normal silica-soda-calcium glass of the Planil ux type marketed by Sain t-Gobain Vi trag). - It has also been seen above that it was possible to obtain, with the method according to the invention, reduced glasses, whose important redox, the percentage of iron content, and the very small sulphate rate, allow the obtaining of residual blue color glasses . With the method according to the invention, glasses of zero or almost zero rate of alkaline oxides of the Na02 type can also be manufactured, especially for applications for fire-resistant glazing or for substrates used in the electronics industry.

For this type of compositions, one can report above all on the patents EP-526 272 and EP-576 362. Other glasses, especially of small MgO rate of the type of those described in the patents: EP-688 741 and O-096/00194 can also be manufactured with the process of the invention. A first embodiment is therefore represented in FIG. 1: a channel 1 allows both to introduce a part of the vitrifiable materials into the melting chamber 2 through the vault 3 and to evacuate the combustion fumes. These fumes will preheat those vitrifiable materials; your thermal energy is recovered in that way. The raw materials that can also be introduced above the bath 7, comprise mainly silica, which can be preheated without taking in the dough. The rest of the raw materials is injected in at least one point 1 located below the level of the glass bath 7, above all by an opening fed by a worm screw. Here, only one injection point is shown, which is moreover relatively high in relation to the total height of the glass bath B, in the vicinity of two thirds (2/3) of that height and on the front wall of the camera.

In fact, several injection points can be provided in the walls (front walls or side walls) at that same height or not, especially, either to the upper half, or to the lower half of that height B, for example between a third (1/3) part and two thirds (2/3) of that height. In fact, this injection directly into the glass bath allows the volatility rate (emissions of solid powders) to be greatly reduced above the bath. In addition, according to its configuration, it allows to direct the materials where the convective mixing is stronger and / or take into account that condition, so that these materials remain at least some minimum time in chamber 2 before passing in the tuning area . The hearth 4 of the chamber is equipped by rows of burners 5 which pass through it and penetrate into the melting chamber at a reduced height. The burners 5 are preferably provided with cooling means, not shown, of the water box type. The burners 5 in operation develop combustions in zones 6 that create in their vicinity, currents of convection within the vitrifiable matter in the course of liquefaction. This convective mixing creates a foam that will transfer the thermal energy in the bath assembly 7. The melting is preferably carried out towards 1350 ° C, for example for a normal glass of the family of silica-soda-calcium glasses. The walls of the chamber 2 which are in contact with the glass bath 7, are here made with cooled refractory materials, on the outer side, by a cooling system of the water box type (not shown). A variant consists in that this cooling system, in the metallic walls, is against the refractories, but from the inner side and is therefore in contact with the molten glass. These two variants allow the wear of the refractories to be reduced by superficially cooling the glass in the vicinity of the refractory walls. The operation of the burners 5 was adapted to the submerged melt in the manner very schematically shown in figure 5. Figure 5a represents a longitudinal section of a burner 5 and figure 5b represents a cross section, at the level of the plane AA 'indicated in figure 5a of this. The burner is bent with a cooling system 50 of the water box type and with a central duct 51 around which a plurality of ducts 52 are arranged concentrically; all those cylindrical section ducts come to empty into the "nose" of the burner 53.

In normal operation (operation [a]), the conduit 51 is supplied with natural gas (or other fuel gas or fuel) gas, and the conduits 52 are supplied with fuel, here oxygen for example); the CH ^ / 02 interaction creates a combustion in the glass bath. In safety operation (function [b]), that is to say when it is desired to stop combustion at the level of the burner without the risk of completely igniting it, nitrogen is injected via conduit 51 and / or via conduits 52. In operation it is intended to allow the exchange of one burner for another (operation [c]), water is injected through line 51, water that is vaporized instantaneously in the burner itself or from the outlet of the burner; the vapor creates a type of glass vault cooled above the burner; then any operation of the burner is stopped and then there is time to effect the exchange, before the "vault" collapses. The injected water is partially collected in the burner by means of the conduits 52 (the roles of the conduits 51 and 52 can also be reversed in this operating mode). Likewise, water can be replaced by any other cooling fluid that can set the glass in that way.

The burner and its different modes of operation that are described in the foregoing are an object of the invention, independently of the overall melting and tuning operation involved in the glass installation. The molten foamed glass coming from the melting by means of the submerged burners is then taken in the lower part by a channel 8 provided with a load-loss regulating means of the punch type, not shown. In this way, the pressure loss of the foam glass entering the static tuning compartment 9 is controlled. This compartment comprises side walls 10, a bottom wall 11 at the same level as the bottom of the melting chamber, and a wall upper 12 that delimits an interior volume practically parallelepiped. A separation partition 13 fixed to the bottom wall 11 is also provided, but which leaves a passage in the upper part. This assembly also defines a channel 14 that imposes on the glass, an ascending trajectory, and then a channel 15 that imposes a downward trajectory on the glass. In the upper part 16, a level of glass H is formed. The refined glass is then taken by a channel 17 that comes to feed a compartment 18 that brings the glass to the formation facility of the float type, not shown. In the tuning compartment, the channel area 14 is placed under reduced pressure, for example 0.3 atmosphere. The glass that comes from channel 8 then goes up in that channel; the residual residual non-melts are "digested" progressively and the bubbles grow in size as they rise in the channel. The expansion rate of the foam remains very moderate, however, thanks to the fact that the foam coming from the melting chamber 3 has a very small residual sulphate rate. In zone 16, the bubbles burst on the surface H, the foam quickly disappears, and the globally refined glass goes down again along the channel 15. If necessary, an auxiliary means can be provided in this zone 16. of heating, of the conventional burner type or electrical resistances hooked to the wall 12 and possibly mechanical means, not shown, intended to facilitate the bursting of the bubbles of the barrier type. To give a size order, it can be foreseen that the height h of the tuning compartment is of the order of a few meters, for example 3 meters for the selected reduced pressure of 0.3 atmosphere.

Figures 2 and 3 represent the second embodiment. The fusion chamber 2 is globally of the same concept as that shown in figure 1. The only difference lies in the way in which the walls of the refractories of chamber 2 are protected. Here, it has been immersed in the glass bath 7, a refractory metal lining constituted by a thin wall of molybdenum 40 which takes the shape of the cavity of the melting chamber and which is maintained at a distance of one to a few millimeters from the walls of the refractories, by means of appropriate wedges and / or being suspended in the glass bath by the walls of the refractories located above the bath or by the vault. This plate 40 is perforated with holes, first in the horizontal zone that comes to line the sill 4, so as to be able to cross with the burners 5, as well as in all the other walls, with a homogeneous distribution in the holes; therefore, this perforation does not prevent the refractory / molten glass contact, on the contrary it mechanically breaks the convection movements of the glass in the vicinity of the refractories, and thus decreases its wear. The holes 41 of the walls of the lining 40, except for those that line the hearth, are preferably cylindrical and of variable dimensions; those of the wall of the hearth side must at least comprise orifices 42, of a size sufficient to allow the burners to pass. The lining 40 must also be extensively perforated (43) in its wall that lines the front transverse wall of the chamber, so that the glass can be evacuated through channel 20a. The same happens for the zone 1 'of introduction of the raw materials: there is necessarily a complementarity in the openings provided in the refractory walls and in the molybdenum lining. This lining of Mo (designated under the Anglo-Saxon term "Molining"), is by itself an invention, particularly appropriate in association with a melting chamber by submerged burners, independently of the manner in which subsequent eventual tuning may be effected. . (The same thing happens with the cooling of the outer side or glass side of the refractories illustrated in the preceding figure). The other difference with Figure 1 lies in the manner in which the glass is taken from the melting chamber. In the case of figure 2, the glass is taken a little more "up", with a duct 20 which is composed of a first horizontal part 20 (a), a second vertical part 20 (b) and a third horizontal part 20 (c) that opens into the centrifuge apparatus 21. To allow the glass to rise in the channel and thereby feed the centrifuge, it is necessary to place at least zone 20 (b) of the channel under moderate reduced pressure, for example under 0.5 atmosphere. Another variant consists in that the molten glass is taken from the melting chamber in the upper part, for example with the help of a submerged groove, such as this is well known in the field of the glass industry. Figure 3 is concentrated on the horizontal zone 20 (c) of the channel for bringing the melting sparkling glass 20 taken from the melting chamber 2, which feeds with glass the body of the centrifuge 21. It presents an upper part 22 comprised between the piece 23 and the metal plate 24, and a lower part 30 that is placed below the metal plate 24. The piece 23 is hollow, it is a cylinder provided with perforations that allow to regulate the flow rate, the loss of load of the glass that enters the centrifuge 21. The glass also penetrates into the upper part 22 where a partial vacuum of for example 0.1 bar or atmosphere is established. The question of the junction 25 between the static part of the channel 20 and the part put into rotation of the body 21 is raised: A first solution consists in adopting a "dynamic" joint. The frothy glass that emerges from the hollow piece 23 goes, under the centrifugal force, to tend to "rise" in the zone 26 and to exit spontaneously through the space that remained free at the level of the joint 25: it is in this way that the glass itself, ejected continuously, ensures tightness. It is possible to envisage limiting and regulating the flow rate of the ejected glass by modulating the space between the mobile assembly 21 and the fixed assembly 20. Another solution consists in arranging in the joint 25, a so-called rotating joint of adapted composition. It can mainly be a liquid ring rotating joint, which uses a low-voltage liquid of the silicone oil type and whose operating principle is the same as that of the liquid ring vacuum pumps: the liquid ring is centrifuged by rotation and put under pressure opposing the depression that exists in the centrifuge. The glass is then drained through the holes of the plate 24 in the area 23 provided with an air-laying tube 27. This plate, at least for the parts completely immersed in the glass, can advantageously be molybdenum. The outer lining of the internal walls of the centrifuge body can be constituted by electrofused refractory pieces 32 comprising a thermal insulator 31 incorporated in such a way that it is not crushed by the centrifugal force. Also provided is a notch, slot 28 that surrounds the internal wall of part 30 (or discontinuous), which allows capturing all solid particles of density higher than that of glass, of the refractory inclusions type. In effect, the bottom-to-top runoff of the glass in the centrifuge, it is done in the following manner: the plate 24 decomposes the centrifuge into two parts, authorizes a centrifugation of the thin layer glass reducing the height of the apparatus in relation to that which would be necessary without it and without the application of a reduced pressure. One of the conditions for the glass to circulate correctly from bottom to top, is that the glass pressure corresponds to the distance between the upper parts of two parabolas, is greater than the sum of the head losses and the difference between the pressure reduced from part 22 and the ambient pressure from part 23, which is achievable. The glass that drains through the plate 24, therefore, will stick in thin layer against the inner walls of the part 30.; the denser solid particles than the glass then project against the walls and are captured in the slots 28 from where they can no longer exit. On the contrary, the bubbles grow and come, by centripetal action, to burst into the interior of the centrifuge body. At the end, the refined glass is taken in the lower part of part 30, by a channel whose head has approximately a funnel shape 29. Under normal operating conditions, it is not necessary to provide glass heating means; the speed of rotation can be of the order of 700 turns per minute and the height h of the centrifuge of 1 to 3 meters, for example. Figure 4 represents, in a very simplified manner, a possible variant of the tuner according to figures 2 and 3, concentrated on the junction zone 40 between the delivery channel 20c at atmospheric pressure and the body of the centrifuge 21 under reduced pressure: piston 41 which can regulate the pressure drop and the inflow of the glass to be tuned in the centrifuge 21. A molybdenum grating 43, perforated with a molybdenum grid 43, is interposed in the drip hole 42 of the channel 20c towards the centrifuge. preferably cylindrical holes, which plays the role of a feeding row for the centrifuge and which divides the glass jet at the entrance, in a multiplicity of small trickles of glass, represented very schematically under reference 44 and of diameter 1 to some millimeters approximately, for example. In this way, this grid 43 serves as a jet divider; the bubbles found in each trickle 44 are eliminated more quickly than if they were in a much wider section of glass vein. The combination of these small threads 44 with the use of a reduced pressure, allows the bubbles to explode in the glass extremely quickly. The trickles 44 whose bubbles were eliminated, are again found in the lower part of the centrifuge 21 in the form of small droplets that coalesce on their internal walls due to the fact of the centrifugal force.

The use of a jet splitter of this type also has an interest in the case in which the tuning is carried out in a static tuner as that shown in figure 1. In one case as in the other (static or centrifugal tuner) , it is seen that the size of the fusion / tuning devices currently available can be dramatically compressed. It should also be noted that it is advantageous that the partial vacuum, both in the case of the static tuner and in the case of the centrifugal tuner, is a nitrogen vacuum, which facilitates the bursting of the bubbles and which is less harmful to metal parts such as piece 24 of the centrifugal tuner. It is also of interest to add to the vitrifiable materials, tuning aids whose paper is described above, on coke of small granulometry, sulfate, nitrate, fluorine or chlorine.

On the other hand, it should be noted that the molybdenum which is optionally used in the melting chamber and / or in the tuning compartment, may be constituted by platinum. It is important to note that, even if the combination of a melting by means of submerged burners with a tuning using a partial pressure setting, is extremely advantageous, the invention also relates to those two aspects taken separately. In this way, the melting mode with submerged burners can be used advantageously, with a normal tuning, and reciprocally using a tuning with setting under reduced pressure, which follows a fusion by conventional heating means, remaining anyway and at the same time within the framework of the invention, even if the synergy underlined above is no longer obtained. It should also be noted that the melting mode can be advantageously used by means of submerged burners without having recourse to a tuning in the usual sense of the term. This may be the case in the field of the bundle, where it can be planned to feed the fiber-forming machines by internal centrifugation directly from sparkling glass which is obtained by melting with submerged burners; the centrifugation imposed by this fiber-forming technique performs de facto the refinement of the glass. You can also plan to directly treat the sparkling glass that comes from the melting, to make sparkling glass that is used as an insulator in the field of construction, for example. This melting mode can also be applied to recirculate glass / metal or glass / plastic composite products, as mentioned above, either to produce glass that can be used, or to produce powdered glass to feed a traditional glass-making furnace (according to, above all, the proportion of these composite products in relation to the rest of the more traditional vitrifiable materials).

Claims (35)

1. R E I V I N D I C A C I O N S 1. Fusion and refining procedure for vitrifiable materials characterized in that all or part of the thermal energy necessary for the fusion of the vitrifiable materials is contributed by the combustion of fuel (s) with at least one fuel gas; those fuels / gas or gaseous products that come from combustion, are injected below the level of the mass of the vitrifiable materials; and in that the tuning of the vitrifiable materials after melting, comprises at least one stage of putting into operation at a sub-atmospheric pressure.
2. 2. Method according to claim 1, characterized in that the comburent is based on air, air enriched with oxygen or oxygen.
3. 3. Method according to any of the preceding claims, characterized in that the fuel is of the hydrocarbon fuel type. of the fuel type or natural gas and / or is based on hydrogen.
4. 4. Method according to any of the preceding claims, characterized in that the vitrifiable materials comprise raw materials and / or powdered glass and / or vitrifiable waste and / or fuel elements, especially glass / plastic compounds, glass / metal compounds, materials organic, coal.
5. Method according to any of the preceding claims, characterized in that the melting of the vitrifiable materials is carried out in at least one melting chamber which is equipped with burners passing through its side walls and / or passing through the hearth and / or suspended from the vault or superstructures so that their combustion or combustion gases develop in the mass of the vitrifiable materials, in the course of fusion.
6. 6. - Method according to any of the preceding claims, characterized in that the combustions created by the combustion of fossil fuel with the fuel gas (s) and / or the gases that come from that combustion, ensure convection, the mixing of vitrifiable materials.
7. 7. Method according to claim 5, characterized in that the height of the mass of the vitrifiable materials in the melting chamber and the height at which the combustions / gases that come from the combustion are developed are regulated so that these combustions / combustion gas, remain in the mass of these vitrifiable materials.
8. 8. Method according to any of the preceding claims, characterized in that the melting is preceded by a stage of preheating of the vitrifiable materials, to a great extent at 900 ° C.
9. 9. - Method according to any of the preceding claims, characterized in that the tuning is carried out on the meltable vitrifiable materials of the type to the foamy state, which presents above all a volumetric mass comprised between 0.5 and 2 g / cm3 approximately, especially 1 to 2 g / cm.
10. 10. Method according to claim 9, characterized in that the tuning is carried out on the vitrifiable materials melting of the glass type to the foamy state, which has a sulphate rate of at most 600 ppm by weight in the form of S03 and / or a Most bubbles of at least 200 μm in diameter.
11. 11. Method according to any of the preceding claims, characterized in that the vitrifiable materials contain additives to help the tuning especially reducing additives of the type of coke with average granulometry less than 200 μm, sulfates or additives based on fluorine or of chlorine, of the halogenide type, or nitrates of the NaN? 3 type.
12. 12. Method according to any of the preceding claims, characterized in that all or part of the vitrifiable materials are introduced into the melting chamber below the level of the mass of the vitrifiable materials during the melting process.
13. 13. Method according to any of the preceding claims, characterized in that the tuning is carried out under reduced pressure in an atmosphere of air, of air enriched with inert gas of the nitrogen type, or based on inert gas of the nitrogen type.
14. 14. Method according to any of the preceding claims, characterized in that the sub-atmospheric pressure in which at least a part of the tuning is effected is less than or equal to 0.5 atmosphere, especially in the order of 0.3 to 0.01 atmosphere .
15. 15. Method according to any of the preceding claims, characterized in that the fusion and / or tuning are carried out at temperatures of at most 1400 ° C, especially at most 1380 ° C or 1350 ° C.
16. 16. - Method according to any of the preceding claims, characterized in that the tuning is carried out in at least one static compartment located in front of the melting chamber and of which, at least one zone, is placed under subatmospheric pressure.
17. 17. - Method according to any of claims 1 to 15, characterized in that the tuning is carried out in at least one compartment located in front of the melting chamber, and that can be put into rotation to ensure a tuning by centrifugation, with at least one area of that compartment, especially the most backward, which is put under sub-atmospheric pressure.
18. 18. Device for melting and refining vitrifiable materials, especially intended to implement the method of any of the preceding claims characterized in that it comprises: - at least one melting chamber equipped with burners supplied with fuel (s) and with oxidant (s) of the air or oxygen type; these burners are arranged so as to inject those gases or the gases that come from the combustion, below the level of the mass of the vitrifiable materials that are introduced in that fusion chamber; - at least one tuning compartment in front of the melting chamber and comprising at least one area that can be put under sub-atmospheric pressure.
19. 19. Device according to claim 18, characterized in that the melting chamber is equipped with at least one means for introducing vitrifiable materials below the level of the mass of the vitrifiable materials in the course of melting, especially at least two. , preferably in the form of an opening (s) associated with a conveyor means of the worm type.
20. 20. Device according to claim 19, characterized in that the walls of the melting chamber, especially those intended to be brought into contact with the mass of the vitrifiable materials in the course of melting, are based on refractory materials. associated with a fluid cooling system of the water type.
21. 21. Device according to any of claims 18 to 20, characterized in that the walls of the fusion chamber, especially those that are intended to be in contact with the mass of the vitrifiable materials in the course of melting, are based on Refractory materials lined with a molybdenum metal coating.
22. 22. Device according to claim 21, characterized in that said coating is kept at a distance from the walls constituted by the refractory materials.
23. 23. Device according to any of claims 21 or 22, characterized in that said coating constitutes a contact surface with the melted materials that is continuous or perforated with holes.
24. 24. Device according to any of claims 18 to 23, characterized in that at least a part of those of the burners of the melting chamber, is designed to be able to inject into the mass of the vitrifiable materials, a fluid, which it does not participate in the combustion, in substitution to the oxidizer and / or the fuel, especially an inert gas of the N type and / or a cooling fluid of the water type.
25. 25. Device according to any of claims 18 to 24, characterized in that the tuning compartment is static, in elevation, and in that it comprises a practically vertical internal separation that delimits, with the walls of the compartment, at least two channels, which successively a first channel that imposes to the vitrifiable materials in fusion, an ascending trajectory and a second channel that imposes to those vitrifiable materials in fusion, a downward trajectory.
26. 26. - Device according to claim 25, characterized in that the first channel is put under sub-atmospheric pressure, at least in part.
27. Device according to any of claims 25 or 26, characterized in that said channel is equipped with means (s) for regulating / controlling the loss of charge of the vitrifiable materials in fusion, at the entrance of the tuning compartment.
28. 28. Device according to any of claims 18 to 24, characterized in that the tuning compartment is static in elevation, and in that it comprises means for introducing melt materials to be refined in the upper part, and means for evacuation of materials tuned at the bottom; these subjects globally follow a mainly vertical descending trajectory in that compartment.
29. 29. - Device according to any of claims 18 to 24, characterized in that the tuning compartment comprises at least one apparatus that can be put into rotation to ensure the tuning by centrifugation; the internal walls of this apparatus virtually define the shape of a vertical hollow cylinder, at least in its median part.
30. 30. Device according to claim 28, characterized in that the apparatus comprises an upper area of sub-atmospheric pressure and a lower area of ambient pressure, which are separated from one another, by one or more mechanical means of the perforated metal plate type. with hole (s).
31. 31.- Device according to any of claims 29 or 30, characterized in that the apparatus is fed in its upper part with vitrifiable materials in fusion, by means of static conveyance of the type runoff channel, with sealing means between the means of static and the device, type "dynamic joint" or rotary joint.
32. 32. Device according to any of claims 29 to 31, characterized in that the apparatus is provided with means for capturing solid particles that are located mainly in its lower area and in the form of notches / grooves made in its internal walls. 33.- Device according to any of claims 29 to 32, characterized in that the speed of the apparatus is between 100 and 1500 rounds per minute. 34. - Device according to any of claims 29 to 33, characterized in that the apparatus is provided with fixed mechanical means or that follow its rotation, and that can crush the foam and bring it to the lower area of the apparatus, especially in the form of deflectors or fins perforated and arranged in the upper area of the apparatus. 35.- Process of fusion of vitrifiable materials, characterized in that a part of the thermal energy necessary for the fusion of these vitrifiable materials, is provided by the combustion of co-bust (s) with at least one oxidizing gas; that gas (s) called fuel / gas or gaseous products that come from combustion, are injected below the level of the mass of the vitrifiable materials. Declaration according to article 19.1 The added claim 35, which relates only to the melting process of the vitrifiable materials, is supported by the description, in particular: - on page 2, lines 21-28; - on page 26, lines 3-5 and 11-13.