Preparation of the raw material composition

Abstract

A method for preparing a raw material composition suitable for feeding into a melting chamber of an apparatus suitable for obtaining crushed glass, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulated glass, the method being characterized by comprising at least one step of grinding a mineral wool mixture suitable for feeding into the raw material composition, such that the bulk density of the resulting particulate mixture is greater than or equal to 30 kg / m³. 3 .

Description

[0001] This invention relates to a method for preparing a raw material composition suitable for charging in a glass melting furnace. The invention also relates to the resulting raw material composition and a method for melting the composition. Finally, the invention relates to a method for producing cullet, glass wool and / or rock wool, woven glass yarn and / or flat glass, or insulating glass (bottles, flasks, etc.), or a method performed after said melting method.

[0002] More specifically, the raw material composition according to the invention is obtained from a mineral wool blend. In the sense of the invention, this mineral wool blend comprises one or more types of mineral fibers derived from the production of said fibers (factory waste), construction sites (construction site waste or demolition site waste), and / or recycling facilities that allow the recovery of such fibers from the final product, regardless of whether they have been used. In practice, different steps in mineral wool production generate a certain amount of waste that enters the composition of said mineral wool blend. For example, this waste may come from the cutting of products (and / or discarded products) and at this time contains a large amount of organic material, such as a resin called "adhesive" designed to ensure the mechanical cohesion of the fiber mat. Other types of materials may be used in combination with the mineral fibers, such as paper films, aluminum-based films, or bitumen films, or wooden pallet components. These mineral fibers may in particular be composed of glass and / or rock. They are then referred to as glass wool and rock wool, respectively. These mineral fibers are typically used in combination with organic adhesives and other metallic and / or organic materials.

[0003] In this context, as described in the specification of patent EP1 771391B 1, it is known to "recycle" a mineral wool mixture by melting it in a glass furnace to produce cullet glass, or in other words, a mineral material suitable for use as a vitrification feedstock in subsequent glass melting processes. Among the many advantages of this mineral wool waste recycling is, in particular, improved energy efficiency of the glass furnace, because the collected mineral wool mixture and / or the cullet glass produced by its melting is more easily melted than "conventional" feedstock compositions that, among other things, contain a significant amount of silica.

[0004] Despite these advantages, the inventors have found that, in practice, this mineral wool blend occupies a considerable volume when introduced into the furnace, for example, via a screw feeder. At a constant feed rate, using a feed composition consisting of this mineral wool blend tends to significantly reduce the mass of feed introduced into the furnace per unit time compared to so-called "conventional" feed compositions. In other words, using this mineral wool blend as a feedstock correspondingly reduces the furnace feed rate, and thus reduces furnace efficiency, which has proven to be a significant drawback in an industrial context.

[0005] The natural solution to this technical problem lies in increasing the capacity of the feeder, for example, by using a larger screw feeder. However, this solution is not without its drawbacks, as it requires structural modifications to the feeder and, more generally, its size depends on the type of composition being fed.

[0006] The claimed invention aims to provide a technical solution to the shortcomings described above. More specifically, in at least one embodiment, the proposed technology relates to a method for preparing a raw material composition suitable for feeding into a melting chamber of an apparatus suitable for obtaining crushed glass, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulated glass, the method being characterized in that it includes at least one step of grinding a mineral wool mixture suitable for entering the raw material composition, such that the resulting particle mixture has a particle size greater than or equal to 30 kg / m³. 3 The packing density.

[0007] Throughout this specification, the term "bulk density" (a synonym for "uncompacted apparent density," more precisely, apparent density) refers to the mass of a crushed mixture per unit total volume, including the interstitial spaces separating the aggregates (particles) constituting the mixture. For the purposes of this invention, this bulk density is measured according to the operating procedures described in the specification or by any operating procedure that allows for equivalent results.

[0008] The milled mineral wool blend contains one or more types of mineral fibers derived from the production of said fibers, on-site (construction or demolition), and / or from recycling facilities that allow the recovery of such fibers from the final product, regardless of whether they have been used. These mineral fibers can, in particular, be composed of glass and / or rock. They are then referred to as glass wool and rock wool, respectively.

[0009] The preparation method according to the invention allows for increasing the bulk density of the mineral wool mixture through grinding, thereby obtaining a particulate mixture that can be fed into so-called "conventional" glass furnaces at a satisfactory feed rate. As detailed in the specification, the use of this particulate mixture particularly allows for a feed mass rate of greater than or equal to 5 tons / day under standard feed conditions below the glass bath level. The selection of this minimum bulk density takes into account, in particular, the empirically observed difference between the theoretical value of the feed mass rate and the actual value of this rate measured under standard operating conditions.

[0010] According to one particular embodiment, the obtained particulate mixture has a particle size greater than or equal to 50 kg / m³. 3 Preferably greater than or equal to 70 kg / m 3 Preferably greater than or equal to 90 kg / m 3 Preferably greater than or equal to 100 kg / m3 .

[0011] The increased bulk density of the particulate mixture allows for a higher feed rate to the furnace, thereby increasing the furnace's productivity.

[0012] According to one particular embodiment, the bulk density of the particle mixture obtained after grinding is less than or equal to 500 kg / m³. 3 .

[0013] As detailed in the specification, melting tests conducted on submerged burner furnaces have shown that above a certain bulk density value, a portion of the introduced feedstock composition, due to its high volatility, tends to be emitted with the flue gas. This complicates the handling of these flue gases, reduces furnace productivity, and thus represents a major industrial drawback. In this regard, as detailed in the specification, a bulk density of 500 kg / m³ or less is preferred. 3 The particulate mixture allows for maintaining an acceptable particulate mixture flue loss (pourcentage d′envol) because the percentage is less than 3%.

[0014] According to one particular embodiment, the bulk density of the obtained particulate mixture is less than or equal to 400 kg / m³. 3 Preferably less than or equal to 300 kg / m 3 More preferably less than or equal to 220 kg / m 3 .

[0015] Limiting the bulk density of particulate mixtures allows for a reduction in the percentage of feedstock losses in flue gas, thereby facilitating flue gas treatment.

[0016] According to a particular embodiment, the mass ratio of the particulate mixture to the total mass of the raw material composition is greater than or equal to 5%, preferably greater than or equal to 20%, preferably greater than or equal to 40%, preferably greater than or equal to 60%, preferably greater than or equal to 70%, preferably greater than or equal to 80%, preferably greater than or equal to 90%, preferably greater than or equal to 95%, preferably greater than or equal to 99%.

[0017] According to one particular embodiment, the preparation method includes the step of adding crushed glass to the particulate mixture, wherein the mass of the crushed glass is greater than or equal to 1% of the total mass of the particulate mixture.

[0018] The inventors have observed that adding crushed glass to a particulate mixture (and thus after grinding) tends to alter its rheological behavior and thus facilitate its transport, particularly during the feeding of the raw material. This is therefore termed "fluidization" of the particulate mixture. A minimum proportion of 1% corresponds to the minimum threshold at which this fluidization effect of the particulate mixture is observed.

[0019] The introduction of shattered glass has an additional advantage: it allows it to be processed for later use, for example by removing unwanted compounds in a submerged combustion furnace.

[0020] According to one particular embodiment, the mass of the shattered glass is less than or equal to 20% of the total mass of the particulate mixture.

[0021] Since quartz glass itself is produced by melting raw materials, the addition and melting of quartz glass, which accounts for more than 20% of the total mass of the particulate mixture, often reduces the overall energy efficiency of the method by an unacceptable proportion due to the non-negligible energy cost.

[0022] According to one particular embodiment, the added shards of glass have a particle size between 1 and 5 mm.

[0023] In this paper, "particle size" refers to the size of aggregate determined by sieving on a screen. Selecting a particle size range of 1-10 mm for crushed glass allows for optimization of the fluidization of the crushed glass to the particle mixture.

[0024] According to one particular embodiment, the preparation method includes a preliminary step of determining the desired bulk density value of the milled particle mixture based on the size characteristics of the feeder used and / or the desired feed mass rate value.

[0025] By pre-determining and subsequently considering the desired density value, it is possible to adjust the method of preparing the raw material composition to achieve the target feed rate by using a feeder with known dimensional characteristics.

[0026] According to one particular embodiment, the moisture content of the mineral wool mixture is greater than 1% of the total mass of the mixture.

[0027] As detailed in the instruction manual, testing activities conducted on the mill have confirmed that increasing the moisture content of the mineral wool blend allows for a further increase in the bulk density of the granular mixture obtained after milling, regardless of the mass introduced by the addition of water. In fact, water acts as a binder by forming capillary bridges between the fibers, which allows the fibers to better adhere together.

[0028] According to one particular implementation, water is supplied, for example by spraying, before and / or during grinding.

[0029] Another advantage of humidifying the mineral wool mixture during the grinding process is that it limits dust emissions.

[0030] According to one particular embodiment, the moisture content of the mineral wool mixture is greater than 2%, preferably greater than 3%.

[0031] Increasing the moisture content allows for a further increase in the bulk density of the particulate mixture. When the particulate mixture is conveyed on a conveyor belt, the upper limit of 25% corresponds to a threshold beyond which the particulate mixture tends to adhere to the conveyor belt and thus block and / or damage it.

[0032] According to one particular embodiment, the preparation method uses at least one grinding machine equipped with a sieve with a mesh size of less than 20 mm.

[0033] Choosing this mesh size will result in a bulk density greater than or equal to 30 kg / m³. 3 A mixture of granules.

[0034] According to one particular embodiment, the mesh size of the screen is less than 20 mm, preferably less than 15 mm, and more preferably less than 10 mm.

[0035] Choosing increasingly smaller mesh sizes allows for the production of particle mixtures with increasingly higher densities.

[0036] According to one particular embodiment, the grinder is adapted to rotate at a speed greater than 150 rpm, preferably greater than 175 rpm, and more preferably greater than 200 rpm.

[0037] The output of a grinding mill often increases with the rotational speed of its drum.

[0038] According to one particular embodiment, the ground mineral wool mixture comprises, when not bonded:

[0039] SiO2: 30 to 75% by weight

[0040] CaO + MgO: 5 to 40% by weight

[0041] Al2O3: 0 to 30% by weight

[0042] Na2O + K2O: 0 to 20% by weight

[0043] Iron oxide: 0 to 15% by weight.

[0044] According to one particular embodiment, the abrasive mineral wool mixture is composed of rock wool (also known as "black glass" by those skilled in the art), which, when not bonded:

[0045] SiO2: 30 to 50% by weight

[0046] Al2O3: 10 to 22% by weight

[0047] CaO + MgO: 20 to 40% by weight

[0048] Iron oxide: 3 to 15% by weight

[0049] Na₂O + K₂O: 1 to 10% by weight.

[0050] According to one particular embodiment, the ground mineral wool mixture consists of glass wool, which, when not bonded:

[0051] SiO2: 50 to 75% by weight

[0052] Al2O3: 0 to 8% by weight

[0053] CaO + MgO: 5 to 20% by weight

[0054] Iron oxide: 0 to 3% by weight

[0055] Na₂O + K₂O: 12 to 20% by weight

[0056] B2O3: 2 to 10% by weight.

[0057] According to one particular embodiment, the ground mineral wool mixture comprises, without adhesive:

[0058] SiO2: 39 to 44% by weight

[0059] Al2O3: 16 to 27% by weight

[0060] CaO: 6 to 20% by weight

[0061] MgO: 1 to 5% by weight

[0062] Na2O: 0 to 15% by weight

[0063] K2O: 0 to 15% by weight

[0064] Na₂O + K₂O: 12 to 20% by weight

[0065] P2O5: 0 to 3% by weight

[0066] Fe2O3: 1.5 to 15% by weight

[0067] B2O3: 0 to 2% by weight

[0068] TiO2: 0 to 2% by weight

[0069] The present invention also relates to a raw material composition suitable for feeding into the melting chamber of an apparatus suitable for obtaining, preferably by such preparation method, cullet, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulating glass, characterized in that it comprises a bulk density greater than or equal to 30 kg / m³. 3 A mixture of granules.

[0070] According to one particular embodiment, the particulate mixture has a concentration greater than or equal to 50 kg / m³. 3 Preferably greater than or equal to 70 kg / m 3 Preferably, it is greater than or equal to 90 kg / m 3 Preferably, it is greater than or equal to 110 kg / m 3 The packing density.

[0071] According to one particular embodiment, the particulate mixture has a concentration of less than or equal to 500 kg / m³. 3 Preferably less than or equal to 400 kg / m 3 Preferably less than or equal to 300 kg / m 3 Preferably less than or equal to 200 kg / m 3 Preferably less than or equal to 160 kg / m 3 Preferably less than or equal to 140 kg / m 3 The packing density.

[0072] According to a particular embodiment, the raw material composition comprises at least 30% by weight, preferably at least 60% by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight, and more preferably at least 98% by weight of a particulate mixture.

[0073] According to one particular embodiment, the raw material composition comprises at least 1% by mass of chopped glass as part of the total mass of the particulate mixture.

[0074] According to one particular embodiment, the mass of the shattered glass is less than or equal to 20% of the total mass of the particulate mixture.

[0075] The present invention also relates to a method for melting such a raw material composition to obtain shattered glass, glass wool and / or rock wool, woven glass yarn and / or flat glass / insulating glass.

[0076] According to one particular embodiment, the raw material composition is fed by a feed screw, preferably from a buffer hopper containing the raw material composition.

[0077] Compared to pistons that operate in a feed cycle, endless screws allow for continuous feeding, which is particularly useful when feeding below the glass bath level.

[0078] Using a buffer hopper preferably equipped with a scale at the outlet allows for precise adjustment of the mass introduced into the feeder.

[0079] According to one particular embodiment, the raw material composition is fed at a feed rate of 5 tons / day or greater.

[0080] According to one particular embodiment, the feedstock composition is fed at a mass rate of 7 tons / day or more, preferably 9 tons / day or more, preferably 10 tons / day.

[0081] The overall yield of the furnace increases with increasing feed rate, so there is interest in increasing it. Using the feed composition according to any one of claims 7 and 8 allows for easier achievement of such a feed rate value.

[0082] According to one particular implementation, the bulk density of the particulate mixture is measured periodically, manually, and / or automatically.

[0083] According to one particular implementation, the bulk density of the particle mixture is manually and / or automatically adjusted according to the desired feed rate.

[0084] According to one particular embodiment, the raw material composition is fed below the glass bath level, and preferably the melting method employs a melting chamber equipped with an immersion burner.

[0085] In this specification, the terms "liquid glass" and "glass bath" refer to the molten products of these vitrifiable materials introduced into the glass furnace. For the purposes of this invention, "immersion burners" are understood to be burners constructed such that the flames and / or combustion gases they produce develop within the glass bath itself. Typically, they are arranged flush with the bottom liquid level so that the flame develops within the same vitrifiable material body during liquefaction (melting). Thus, they can be made to pass through their sidewalls, bottom (lower partition wall), and / or suspended from above by suspending them from a vault or any suitable superstructure. These burners can have their gas supply lines flush with the walls they pass through. It is preferable that these lines at least partially "enter" into the vitrifiable material body to avoid the flame being too close to the partition wall and to avoid premature wear of the refractory material. Alternatively, it is also possible to inject only combustion gases, with combustion taking place more precisely outside the melting chamber.

[0086] Compared to "conventional" melting, the use of a submerged combustion furnace allows for a significant increase in throughput. In effect, melting via a submerged burner generates convective mixing within the vitrifiable material during the liquefaction process. This mixing between the undiluted and molten material is highly efficient and allows vitrifiable materials of the same chemical composition to melt at lower temperatures and / or faster than with conventional heating devices. This results in highly advantageous "stirred" melting characteristics, eliminating the need for unreliable and / or rapidly agitating mechanical stirrers. This is highly beneficial because it reduces the energy costs of the furnace and also because of the choice of refractory materials used in the preparation apparatus: they are lower-temperature materials that corrode more slowly.

[0087] According to one particular embodiment, the raw material composition is fed above the glass bath level, and preferably the melting method uses a melting chamber equipped with a flame burner arranged above the glass bath level.

[0088] The advantage of feeding the raw material composition above the glass bath level is that it allows the organic matter present in the composition to burn before it is introduced into the glass bath, which allows the use of the additional energy generated by these organic matter while limiting contamination of the glass bath.

[0089] In this context, a reduced thickness of the composition batch fed onto the glass bath surface allows for better melting while limiting the risk of particles flying out through the chimney. Therefore, the composition according to the invention is particularly suitable because it has a reduced volume and thus a reduced thickness for equivalent mass.

[0090] The present invention also relates to a method for preparing shattered glass, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulating glass, including such a melting method.

[0091] As discussed in this article, the implementation of this melting method allows for particularly advantageous production yields.

[0092] The present invention also relates to shattered glass, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulated glass obtained according to this preparation method.

[0093] Other features and advantages of the invention will be apparent from the following description of specific embodiments given by way of illustrative and non-limiting example only, as well as the appendix. Figure 1 [ Figure 1 And thus it becomes obvious, attached Figure 1 This is a flowchart illustrating a method for preparing crushed glass, glass wool and / or rock wool, woven glass yarn, flat glass and / or insulated glass according to a specific embodiment of the present invention.

[0094] Throughout the instruction manual, including Figure 1 Unless otherwise stated, the same reference numerals denote similar or identical elements.

[0095] It should also be understood that the present invention is by no means limited to the specific embodiments described and / or introduced, and that other embodiments may be perfectly implemented.

[0096] Figure 1 This is a flowchart illustrating a method for preparing a glass product (5) according to a specific embodiment of the present invention. In a conventional manner, a raw material (4) obtained at least partially from a mineral wool mixture (1) is fed (step S3) into a glass furnace for melting (step S4) and subsequently processed into a glass product (5).

[0097] According to known methods, the molten mixture may alternatively be cooled and crushed to obtain sharded glass, fiberized to obtain glass wool or rock wool, drawn into glass textile yarn and / or poured onto a tin bath to obtain flat glass, each of these industrial applications being referred to throughout the specification as “glass product (5)”.

[0098] According to a particular embodiment of the invention, this preparation method includes making at least partially [a substance] with a bulk density greater than or equal to 30 kg / m³. 3 The raw material composition (4) obtained from the particulate mixture (2) is melted.

[0099] According to a reproducible procedure for measuring the bulk density of the particulate mixture (2), the particulate mixture is first poured into a container of known mass and volume, such as a bucket. The container must be at least 20 liters in size to ensure sufficient accuracy and to comply with the aspect ratio limiting the compaction of the mixture, by satisfying the following formula:

[0100] [Mathematical Expression 1]

[0101]

[0102] Where L max V is the maximum amplitude of the container in a given direction, similar to the Féret diameter of a particle, and V is the volume of the container.

[0103] It is equally important to ensure that the mixture is poured gently, without moving the bucket or mechanically compressing it, to minimize compaction. Then weigh the full bucket to determine the mass of the poured mixture. Bulk density is the ratio of the measured mass of the mixture to the volume of the bucket.

[0104] It is important to note that this method of characterizing bulk density is significantly more accurate and rigorous than any alternative method that merely estimates the size of the fiber agglomerates (also known as “sheets”). In fact, any mineral wool blend (1) can be viewed as an agglomeration of mineral fibers with an expandable or compressible volume, which itself can be divided into multiple agglomerates of smaller and / or lower-density fibers. Without additional information, the size of the mineral fiber agglomerates cannot therefore be used as data to characterize the product and / or compare two products.

[0105] To more accurately estimate the glass feed rate as a function of variations in various furnace operating parameters and the bulk density of the feed composition, the inventors conducted experiments by feeding two batches of glass with feed rates of 20 kg / m³. 3 and 110kg / m 3 Testing activities for the bulk density of glass wool waste.

[0106] Two types of tests were implemented:

[0107] - "Cold" test, in which glass wool waste is fed into the feed screw over a given time period, and then the glass wool waste is collected and weighed at the feeder outlet to infer the mass flow rate of the feeder.

[0108] - A "hot" test was conducted, for which the same feeder was installed at the inlet of the working furnace. A known mass of scrap was input and the time required for the total input was recorded to calculate the feed rate.

[0109] For each of the two tests, the endless feed screw had a diameter and pitch of 30 cm. The fill rate was 100%, with the screw hopper fully loaded to ensure continuous feeding.

[0110] Simultaneously with these two industrial tests, the theoretical feed rate values ​​were calculated under the same operating conditions based on the following formula, which gives an approximate value (in kg / s) of the feed rate Q carried by the screw:

[0111] Q = r * d * V * π * R 2 *H,

[0112] Where r is the screw filling rate, d is the density of the feed mixture (in kg / s), and V is the rotational speed of the endless screw (in s). -1 (10 rpm under standard feeding conditions), R is the screw radius (in meters), and H is the screw pitch (in meters).

[0113] Table 1 below shows the results obtained for four glass wool samples with different bulk densities. These four samples were fed into the furnace by an endless screw at different screw speeds.

[0114]

[0115] Table 1 - Variation of feed rate as a function of different furnace operating parameters and the bulk density of the feed composition

[0116] By comparing the theoretical feed rate values ​​with the results obtained from cold testing, negligible differences were observed. Therefore, the theoretical feed rate (theoretical value) of the screw conveyor allows for a relatively accurate estimate of the cold test results.

[0117] On the other hand, when comparing the theoretical value of the mass flow rate with the results obtained from this test conducted under high-temperature conditions, a surprising and significant reduction in mass flow rate was observed, between 20% and 40% of the theoretical value. Several hypotheses could reasonably support the justification for this numerical difference, based on empirical observations, including the pressure exerted on the feed mixture by the glass bath and / or the rise of combustion gases from the furnace, which at this point occupy a portion of the available space in the screw.

[0118] This consideration of the difference has direct application in industrial reality. Therefore, it is generally accepted that, for the sake of furnace profitability, the minimum feed mass flow rate of raw materials entering the furnace should be 5 tons / day, or 208 kg / h. If those skilled in the art adhere to theory or results obtained in cold testing—that is, within a testing framework where hot testing is significantly easier—they will conclude that, under standard feed conditions, using glass wool waste with a bulk density of 20 kg / m³ is sufficient to achieve a feed rate of 232 kg / h, which is a satisfactory rate.

[0119] However, this is not the case. Thermal tests conducted on sample 1 (see Table 1) showed that the actual mass rate obtained was 150 kg / m³, which is far below the set standard flow rate.

[0120] For equivalent operating conditions, and taking into account a maximum deviation of 40%, the bulk density required to obtain a feed rate of 208.8 kg / m³ is almost equal to the minimum set threshold, which is actually 30 kg / m³.

[0121] The threshold for achieving the packing density is not obvious, as it is the result of a series of complex (thermal) tests conducted by the inventors.

[0122] To increase the bulk density of the granular mixture, the inventors used a standard industrial grinding mill and conducted testing activities during which three batches of glass wool waste were ground, and the bulk density of the resulting granular mixture was then measured for each of these batches. The purpose of this activity was specifically to evaluate the effects of various parameters of the grinding mill and the wetting rate on the bulk density of the ground mineral wool mixture.

[0123] The first batch consisted only of standard glass wool boards.

[0124] The second batch corresponds to the first batch, and 8.8 kg of wet glass wool waste was added.

[0125] The third batch corresponds to the second batch, and 6.4 kg of wet glass wool waste was added.

[0126] Five (5) tests were conducted based on these three batches of material. Tests No. 1 to 3 were conducted using the first batch of material, with changes made to the mill settings. Test No. 4 was conducted using the second batch of material, and Test No. 5 was conducted using the third batch of material.

[0127] Table 2 below shows the results obtained for each of these tests. Unless otherwise specified, all parameters not specified in this table are the same for each of these tests.

[0128]

[0129] Table 2 - Variation of bulk density of grinding glass wool waste as a function of grinding mill operating parameters and wetting rate of the grinding mixture.

[0130] Comparing the results of tests 1 and 2, it was observed that reducing the mesh size of the mill screen from 15 mm to 10 mm allowed for a 72% increase in the bulk density of the resulting particulate mixture and a 9.6% increase in the capacity of the mill.

[0131] Comparing the results of tests 2 and 3, it was observed that increasing the drum speed from 150 rpm to 210 rpm allowed for a 6.5% increase in the bulk density of the resulting particulate mixture.

[0132] Comparison of the results of tests 1 and 4 revealed that adding wet waste to the ground glass wool mixture allowed for an increase in the bulk density of the resulting particulate mixture and the capacity of the grinder. This was confirmed by a comparison of tests 4 and 5, where it was observed that increasing the proportion of wet waste further allowed for an increase in the bulk density of the ground mixture and the capacity of the grinder.

Claims

1. A method for the preparation of a raw material composition suitable for being fed into a melting chamber of a plant suitable for obtaining cullet, glass wool and / or rock wool, textile glass yarn, flat glass and / or hollow glass, said method being characterized in that it comprises at least one step of grinding a mineral wool mixture introduced into the raw material composition, so that the granular mixture obtained from the ground mineral wool mixture has a bulk density greater than or equal to 30 kg / m 3 and less than or equal to 500 kg / m 3 .

2. The production method according to claim 1, characterized by, The particulate mixture accounts for more than or equal to 5% of the total mass of the raw material composition.

3. The preparation method according to any one of claims 1 and 2, characterized in that, It includes the step of adding crushed glass to the particulate mixture, wherein the mass of the crushed glass is greater than or equal to 1% of the total mass of the particulate mixture.

4. The preparation method according to any one of claims 1 to 2, characterized in that, It includes a preliminary step of determining the desired bulk density value of the grinding particle mixture as a function of the size characteristics of the feeder to be used and / or the required mass flow rate value.

5. The preparation method according to claim 3, characterized in that, It includes a preliminary step of determining the desired bulk density value of the grinding particle mixture as a function of the size characteristics of the feeder to be used and / or the required mass flow rate value.

6. The preparation method according to any one of claims 1 to 2, characterized in that, It uses at least one grinding machine equipped with a screen with a mesh size of less than 20 mm.

7. The preparation method according to claim 3, characterized in that, It uses at least one grinding machine equipped with a screen with a mesh size of less than 20 mm.

8. The preparation method according to claim 4, characterized in that, It uses at least one grinding machine equipped with a screen with a mesh size of less than 20 mm.

9. The preparation method according to claim 5, characterized in that, It uses at least one grinding machine equipped with a screen with a mesh size of less than 20 mm.

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