Melting and fiberization of recycled rock wool

Abstract

The present invention relates to a raw material composition suitable for being charged into a glass furnace, melted, and subsequently fibrousized by internal centrifugation, wherein the raw material composition comprises recycled rock wool. The present invention also relates to a method for melting this composition and fibrousizing it by internal centrifugation, and to mineral wool obtained by these methods. The present invention also relates to the use of recycled rock wool as a source of Al2O3, CaO, and MgO for the production of mineral wool.

Description

Technical Field

[0001] The present invention relates to a raw material composition suitable for being charged into a glass furnace, melted, and then fiberized by internal centrifugation, which contains rock wool recycled materials. The present invention also relates to a method for melting this composition and fiberizing it by internal centrifugation, and to the mineral wool obtained by these methods. The present invention also relates to the use of rock wool recycled materials as a source of Al2O3, CaO, and MgO for the production of mineral wool.

Background Art

[0002] It is known to "recycle" a mixture of mineral wool by melting it in a glass furnace for the purpose of fiberizing it again. Among the many advantages of such recycling of mineral wool waste, there is an improvement in the energy efficiency of the glass furnace because the recovered mineral wool mixture is relatively easier to melt than "conventional" raw material compositions that contain, among other things, large amounts of silica.

[0003] Mineral wool is characterized by an entanglement of discontinuous fibers and is distinguished from continuous fibers commonly used for reinforcing organic or inorganic materials (such as cement). Mineral wool can contain one or more types of fibers derived from their production (factory waste), such as the cutting and / or discarding of mineral wool mats, or from construction sites (construction site waste or demolition site waste), and / or from recycling routes that make it possible to recover such mineral fibers from end products, whether used or not. Other types of materials, such as paper, aluminum or asphalt film, or wooden pallet parts, etc., can be combined with the mineral fibers.

[0004] Such mineral fibers can be obtained, in particular, from raw materials conventionally used in the glass industry or from basaltic rocks. These are known as glass wool and rock wool, respectively. These two types of mineral wool differ from each other in their composition, their melting process, and the associated fiberization method.

[0005] In the context of this invention, mineral wool has a chemical composition comprising the following components: SiO2: 30~75% by mass, CaO+MgO: 5~45% by mass, Al2O3: 0~30% by mass, Na2O+K2O: 0~20% by mass, Fe2O3: 0~20% by mass, B2O3: 0~14% by mass, MnO: 0~4% by mass.

[0006] The term "rock wool" generally refers to mineral wool whose fiber chemical composition includes the following components: SiO2: 30~50% by mass, Al2O3: 10~22% by mass, CaO+MgO: 20~45% by mass, Fe2O3: 0~20% by mass, Na2O+K2O: 0~10% by mass, B2O3: 0~1% by mass.

[0007] In contrast, the term "glass wool" generally refers to mineral wool whose fiber chemical composition includes the following components: - In the case of so-called low-alumina glass wool: SiO2: 50~75% by mass, Al2O3: 0~8% by mass, CaO+MgO: 5~20% by mass, Fe2O3: 0~3% by mass, Na2O+K2O: 6~20% by mass, B2O3: 0~14% by mass, MnO: 0~4% by mass; - In the case of so-called high-alumina glass wool: SiO2: 35~55% by mass, Al2O3: 16~27% by mass, CaO+MgO: 3~30% by mass, Fe2O3: 0~15% by mass, Na2O+K2O: 5~17% by mass, B2O3: 0~5% by mass.

[0008] In this application, the composition is expressed in the form of oxides, as in the conventional method. In particular, when the (total) iron oxide content is expressed as Fe2O3, this does not necessarily mean that this iron oxide exists only in the form of iron(III). Iron oxide can exist in both the form of iron(III) (Fe2O3) and the form of iron(II) (FeO), and expressing the total iron oxide content as Fe2O3 is merely a convention.

[0009] Preferably, the total mass concentration of SiO2, Al2O3, CaO, MgO, Fe2O3, Na2O, K2O, and MnO in the raw material composition according to the present invention and the wool composition described in this application is 90% or more, or more specifically, 95% or more.

[0010] It should be understood that the aforementioned mineral wool may contain other oxides, such as P2O5 or TiO2, which are generally present in trace amounts.

[0011] The melting of rock (basalt or blast furnace slag) generally requires heating the raw materials to significantly higher temperatures than that required for melting so-called glass raw materials. Traditionally, this process has been carried out in cupola furnaces, which heat large quantities of coke to approximately 1500°C. In fact, the refractory furnaces conventionally used for melting glass raw materials cannot withstand the high temperatures required to melt rock.

[0012] Similarly, the fiberization processes for these mineral wools are not interchangeable because they depend directly on their respective compositions.

[0013] Therefore, a commonly used fibrosis method for producing rock fibers is known as external centrifugation. In this method, the material to be fibrousized is poured in a molten state onto the peripheral tread of a rotating centrifuge wheel, accelerated by these wheels, separated from it, partially deformed into fibers under the influence of centrifugal force, and a gas stream is released tangentially to the peripheral tread of the wheel, thereby separating the fibrous material from the unfibrous material and recovering it, which is then transported to a receiver. For example, fibrosis by external centrifugation may be referenced in European Patent Application Publication No. 0195725.

[0014] This method of fiberizing rock wool is distinct from those commonly used for fiberizing glass wool (low-alumina or high-alumina type), and is called the internal centrifugal separation fiberization method. It involves introducing a molten mesh of the stretchable material into a rapidly rotating centrifugal separator, also known as a fiberization spinner. Such a fiberization spinner may alternatively have a bottom with numerous orifices perforated around its periphery, through which the material is ejected in a filamentous form under the influence of centrifugal force. These filaments are then subjected to a high-temperature, high-speed annular gas extraction flow along the walls of the centrifugal separator using an annular burner (potentially reaching temperatures of 1000°C or even 1200°C and speeds of 250 m / s, depending on the desired product), which thins them and transforms them into fibers.

[0015] Therefore, significant differences exist between rock wool and glass wool with respect to their composition, their melting process, the physical properties of the molten material discharged from the furnace (and the resulting properties) (temperature, viscosity, etc.), and the associated fiberization methods. Regarding the latter aspect, it should be noted that rock wool compositions are technically impossible to fiberize by internal centrifugal separation, and glass wool compositions are also technically impossible to fiberize by external centrifugal separation.

[0016] Therefore, regarding these technical differences and in the context of recycling used fibers, it is natural for those skilled in the art to allocate rock wool recycling solely to the production of rock wool and glass wool recycling solely to the production of glass wool, and not to consider at all mixing these two different technical fields.

[0017] The strict separation that exists during the use of one type of glass wool waste and the other type of rock wool waste has the drawback of complicating the associated supply routes by increasing the number of storage locations and / or extending the transportation distance, or by performing sorting before feeding into the melting bath.

Summary of the Invention

Problems to be Solved by the Invention

[0018] The present invention is intended to provide a technical solution to the aforementioned drawbacks. More particularly, in at least one embodiment, the proposed technique relates to a raw material composition adapted to be fiberized by melting and internal centrifugation to obtain mineral wool, particularly glass wool, wherein the raw material composition contains recycled rock wool in a mass ratio of 1% to 50% (for example, 1% to 40%, or even 10% to 40%).

Means for Solving the Problems

[0019] For the purpose of the present invention, the raw material composition is suitable for being fiberized by internal centrifugation when, for a kinematic viscosity of Log3 poise, the temperature of the glass bath (Tlog3) is less than 1400 °C, preferably less than 1300 °C, more preferably less than 1250 °C, even more preferably less than 1200 °C, or even less than 1100 °C, and the difference (Tlog3 - Tliq) between the temperature corresponding to the Log3 poise viscosity value and the crystallization temperature of the glass (also called the liquidus temperature) is more than 35 °C, preferably more than 70 °C, more preferably more than 100 °C, even more preferably more than 110 °C, or even more than 120 °C, for example more than 130 °C. As is well known in the field of glass melting, the kinematic viscosity is expressed in LogN poise, which is 10 NIt corresponds to poise (1 poise = 0.1 Pa·s), and each viscosity value corresponds to a predetermined glass bath temperature. The kinematic viscosity can be measured using a glass viscometer.

[0020] The present invention is based on the concept of introducing rock wool recycled material into a raw material composition intended for melting and thus internal centrifugal fiberization. The fiberization method is usually restricted to the production of mineral wool, particularly glass wool. The addition of rock wool recycled material, which is initially not suitable for fiberization by internal centrifugation in terms of its composition, introduces additional technical difficulties for those skilled in the art responsible for melting and fiberization. Despite these technical difficulties, such addition enables the operator to gain flexibility in the selection of the raw materials used and thus to seize the opportunities that can be temporarily provided by the recycling routes located around the melting and fiberization facilities.

[0021] The solution proposed by the present invention has the advantages of both economy and environmental consideration. In fact, glass wool is usually produced from natural raw materials such as feldspar, dolomite, and lime, etc., which are expensive and / or emit CO2 and / or reduce the melting yield of the glass composition. Using rock wool recycled material as a source rich in Al2O3, CaO, and MgO reduces the use of these raw materials. Furthermore, the reduction in CO2 and water vapor emissions during the production of glass wool using recycled rock wool contributes to an improvement in the material yield, that is, the ratio between the amount of raw material introduced and the amount of molten glass obtained after melting the raw material composition. The use of rock wool also reduces the energy required for melting the raw material composition.

[0022] Therefore, the present invention also relates to the use of rock wool recycled material as a source of Al2O3, CaO, and MgO for the production of mineral wool, particularly glass wool.

Mode for Carrying Out the Invention

[0023] According to a particular embodiment, the raw material composition contains rock wool in mass percent of 2% to 38%, for example, 5% to 35%, 10% to 30%, 15% to 25%, 20% to 38%, or 25% to 38%.

[0024] According to a particular embodiment, the raw material composition contains 1% to 9% by mass of recycled rock wool.

[0025] According to another specific embodiment, the raw material composition contains 10% to 40% by mass of recycled rock wool material.

[0026] Recycled rock wool materials include not only rock wool itself, but also derived forms, such as crushed rock wool or forms in which glass rock aggregates are formed by heating.

[0027] According to certain embodiments, the rock wool regenerated material added to the raw material composition is rock wool that is at least partially bonded. In the sense of the present invention, the term “bonded rock wool” as used herein refers to mineral wool consisting of mineral fibers having an organic binder on their surface, which is already crosslinked. Alternatively, the rock wool may be coated with a thin layer of a sizing agent or lubricant.

[0028] According to certain embodiments, the rock wool regenerated material added to the raw material composition is at least partially virgin rock wool. In the sense of the present invention, the term "virgin rock wool" refers to rock wool obtained by external centrifugation, whose fibers are not bound together by organic binders, in contrast to bonded rock wool. Such virgin rock wool is typically used as blown-in wool for attic insulation or spray-in wool for underfloor insulation.

[0029] According to a particular embodiment, the recycled rock wool material has a chemical composition comprising, by mass percent, the following components: SiO2: 30-50%, Al2O3: 10-22% CaO + MgO: 20-45% Fe2O3: 0-20%, for example, 3-20% Na2O + K2O: 0-10%, for example, 0-8%, and B2O3: 0-1%.

[0030] According to a more specific embodiment, the recycled rock wool material has a chemical composition comprising, by mass percent, the following components: SiO2: 40-48%, Al2O3: 14-19% (e.g., 15-17%) CaO + MgO: 24-33% Fe2O3: 3-20% Na2O + K2O: 0-8% (e.g., 2-8%), and, B2O3: 0-1%.

[0031] For example, recycled rock wool material may have a chemical composition containing the following components by mass percentage: SiO2: 30-50%, Al2O3: 10-22% CaO + MgO: 20-45% Fe2O3: 3-20%, Na2O + K2O: 0-5%, or even 0-4%, and B2O3: 0-1%.

[0032] Furthermore, according to certain embodiments, the recycled rock wool material is, by mass percentage, It has a chemical composition containing the following components: SiO2: 40-48%, Al2O3: 14-19%, for example, 15-17%. CaO + MgO: 24-33% Fe2O3: 5-12% Na2O+K2O: 2~4%, and B2O3: 0-1%.

[0033] For detailed explanations, three exemplary compositions of recycled rock wool are referred to as "Rock Wool 1," "Rock Wool 2," and "Rock Wool 3" (compositions described in the examples below), which fall within these compositional ranges and are commonly used in the insulation industry. Therefore, such waste can be recovered from numerous production sites and / or construction / demolition sites.

[0034] According to certain embodiments, the recycled rock wool material has a boron-free composition. Such a composition is particularly useful in the insulation industry.

[0035] According to a particular embodiment, the raw material composition includes household cullet and / or flat glass cullet. The addition of household cullet and / or flat glass makes it possible to increase the flexibility of the selection of raw materials used.

[0036] According to a particular embodiment, the raw material composition contains Fe2O3 in a mass ratio of 0% to 20%, for example, 0% to 15%, or even 0% to 10%, relative to the solid content mass in the raw material composition. According to a particular embodiment, the raw material composition contains Fe2O3 in a mass ratio of at least 2%, preferably at least 5%, relative to the solid content mass in the raw material composition. Increasing the Fe2O3 content in the raw material composition makes it possible to improve the maximum handling temperature of the resulting fibers after fiberization. In other words, such fibers have relatively good resistance to relatively high temperatures.

[0037] According to a particular embodiment, the raw material composition contains Al2O3 in a mass ratio of 0% to 25%, for example, 0% to 15%, or even more preferably 0% to 10%, relative to the solid content mass in the raw material composition. According to a particular embodiment, the raw material composition contains Al2O3 in a mass ratio of at least 2%, preferably at least 5%, more preferably at least 10%, and most preferably at least 20%, relative to the solid content mass in the raw material composition.

[0038] According to a particular embodiment, the raw material composition contains SiO2 in a mass ratio of 20% to 75%, for example, 30% to 75%, or 20% to 60%, relative to the solid content mass in the raw material composition.

[0039] More specifically, the raw material composition may contain 37% to 75% (e.g., 37% to 60%, or 50% to 75%) of SiO2, 0% to 8% (e.g., 0% to 6%) of Al2O3, and 0% to 3% of Fe2O3, in mass ratio with respect to the solid content mass in the raw material composition.

[0040] Alternatively, the raw material composition may contain 26% to 55% (e.g., 26% to 41% or 35% to 55%) of SiO2, 12% to 27% (e.g., 16% to 27% or 12% to 24%) of Al2O3, and 0% to 15% (e.g., 0% to 12%) of Fe2O3, based on the mass ratio of solid content in the raw material composition.

[0041] According to a particular embodiment, the mineral wool (i.e., the mineral wool in question) has a chemical composition comprising, by mass percent, the following components: SiO2: 30-75%, Al2O3: 0-30% CaO + MgO: 3-45% Fe2O3: 0-20% Na2O + K2O: 4-20% B2O3: 0-14%, and MnO: 0-4%.

[0042] According to a particular embodiment, the mineral wool (i.e., the mineral wool in question) has a chemical composition comprising, by mass percent, the following components: SiO2: 30-75%, for example, 39-70% Al2O3: 0-30%, for example, 1-25% CaO + MgO: 5-45%, for example, 9-22% Fe2O3: 0-20%, for example, 0-10% Na2O + K2O: 0-20%, for example, 1-18% B2O3: 0-14%, and MnO: 0-4%.

[0043] According to a particular embodiment, the mineral wool (i.e., the mineral wool in question) has a chemical composition comprising, by mass percent, the following components: SiO2: 30-75%, for example, 39-70% Al2O3: 0-30%, for example, 1-25% CaO + MgO: 5-45%, for example, 5-18% Fe2O3: 0-20%, for example, 0-10% Na2O + K2O: 4-20%, for example 5-18%, or even 9-18%. B2O3: 0-14%, and MnO: 0-4%.

[0044] According to a particular embodiment, the mineral wool (i.e., the mineral wool in question) has a chemical composition comprising, by mass percent, the following components: SiO2: 35-75%, Al2O3: 0-27% CaO + MgO: 5-45%, for example, 5-18% Fe2O3: 0-15% Na2O + K2O: 4-20%, or even 9-18%, B2O3: 0-14%, and MnO: 0-4%

[0045] For example, mineral wool (i.e., the mineral wool in question) may have a chemical composition containing the following components by mass percentage: SiO2: 30-75%, for example, 39-70% Al2O3: 0-30%, for example, 1-25% CaO + MgO: 5-18% Fe2O3: 0-20%, for example, 0-10% Na2O + K2O: 4-20% B2O3: 0-14%, and MnO: 0-4%.

[0046] More specifically, mineral wool (i.e., the mineral wool in question) may have a chemical composition containing, by mass percentage, the following components: SiO2: 50-75%, for example, 60-70% Al2O3: 0-8%, for example, 1-5% CaO + MgO: 5-20%, for example, 9-14% Fe2O3: 0-3%, for example, 0-1% Na2O + K2O: 6-20%, for example, 12-18% B2O3: 0-14%, and MnO: 0-4%.

[0047] Alternatively, mineral wool (i.e., the mineral wool in question) may have a chemical composition containing the following components in mass percent: SiO2: 35-55% (e.g., 40-50%) Al2O3: 16-27% (e.g., 17-25%) CaO + MgO: 3-30% (for example, 3-18%, or even 14-22%) Fe2O3: 0-15% (e.g., 1-8%) Na2O + K2O: 5-17% (e.g., 7-17%, or even 9-17%, or 10-14%), and, B2O3: 0-5% (e.g., 0-2%) Preferably: SiO2: 35-55%, Al2O3: 16-27%, CaO + MgO: 3-30% (e.g., 3-18%), Fe2O3: 0-15%, Na2O + K2O: 7-17%, and B2O3: 0-5%; More preferably: SiO2: 35-55%, Al2O3: 16-27%, CaO + MgO: 3-30% (e.g., 3-18%), Fe2O3: 0-15%, Na2O + K2O: 9-17%, and B2O3: 0-5%.

[0048] It should be noted that a person skilled in the art will have general knowledge, based on routine testing, to adapt the remaining portion of the raw material composition to meet the technical specifications for fiberization by internal centrifugal separation.

[0049] The present invention further relates to a method comprising the step of melting such a raw material composition in a glass furnace as defined in this application.

[0050] In known forms, such raw material compositions may be melted in a glass furnace having immersion burners and / or non-immersion burners, in an electric furnace, and / or in a hybrid furnace equipped with at least one burner and electrode. At the furnace outlet, the molten composition may be immediately fibrousized by internal centrifugation, or cooled and deformed into cullet, and subsequently remelted and fibrousized by internal centrifugation to obtain mineral wool.

[0051] The present invention further relates to a method for producing mineral wool, characterized in that it involves such a melting method and a subsequent step of fiberizing the molten composition of raw materials by internal centrifugal separation.

[0052] The present invention further relates to mineral wool obtained by such a manufacturing method.

[0053] The remainder of this specification details general methods that a furnace operator may employ to produce the raw material compositions according to the present invention.

[0054] In the first step, a target composition is selected that satisfies the viscosity criteria for fiberization by internal centrifugation. For the purposes of the present invention, such a composition is suitable for fiberization by internal centrifugation when the temperature of the glass molten material (Tlog3) is less than 1400°C, preferably less than 1300°C, more preferably less than 1250°C, and even more preferably less than 1200°C, with respect to the kinematic viscosity Log3 poise, and the difference between the temperature corresponding to the Log3 poise viscosity value and the glass crystallization temperature (also called the liquidus temperature) (Tlog3-Tliq) is greater than 35°C, preferably greater than 70°C, and more preferably greater than 100°C.

[0055] To assist in the selection of the target composition, the furnace operator uses a model that derives the relationship between chemical composition and the kinematic viscosity of the mixture, such as one commonly used in the glass industry.

[0056] In an industrial context and in a known manner, other considerations, such as the final cost of the composition, the energy required for its melting, and its suitability to a specific range of chemical compound concentrations, may also be taken into account when selecting a composition.

[0057] In the second step, the operator prepares the mixture, taking into account the respective chemical composition of each raw material in the disposal, and adjusts the relative proportions of these raw materials to obtain the target composition.

[0058] Alternatively or in combination, these raw materials may be pure oxides, salts (e.g., sodium carbonate, potassium salts, or borax), natural raw materials (siliceous sand, dolomite, limestone, sterile rock, slag, bauxite, feldspar, plagioclase, ferrite, etc.) which are already combinations of oxides, natural raw materials, waste glass and / or rock wool which may originate from the production of the above fibers or from the work site (construction or demolition), waste glass and / or rock wool, any liquid or solid fuel (composite or non-composite plastic materials, organic materials, coal), and any type of glass cullet. Recyclable materials are also included, which include combustible (organic) elements, e.g., mineral fibers (of the type used as reinforcing materials), glazing laminated with sheets of polyvinyl butyral polymer, e.g., windshields, glass bottles (household cullet), or any type of “composite” material combining glass and plastic materials, e.g., certain bottles. Furthermore, "glass-metal composites or metal compounds," such as functionalized glazing with a metal-containing coating, are also recyclable.

[0059] In addition, according to the alternative embodiment, the operator begins by considering the respective compositions of each raw material in the disposal, thereby adjusting their relative proportions, and empirically, based on a model in the disposal, determines and obtains a target composition that satisfies the viscosity criteria for fiberization by internal centrifugal separation.

[0060] Once the target composition is obtained, it is placed in a glass furnace and melted. The melted composition is then fibrousized by internal centrifugation, thereby forming mineral wool. [Examples]

[0061] Further features and advantages of the present invention will become apparent from the following examples, which are for illustrative purposes only and are not intended to limit the scope of the invention as defined by the appended claims.

[0062] Example 1: Low-alumina glass fiber

[0063] The furnace operator selects from the four target compositions of low-alumina glass wool listed in Table 1 below.

[0064] [Table 1]

[0065] For these four target compositions, the liquidus temperature (Tliq) may be approximated from experimentally measured values ​​available in the literature, and the Tlog3 temperature may be calculated using the Fluegel model (A. Fluegel, “Glass Viscosity Calculation Based on a Global Statistical Modeling Approach”, Glass Technol.: Europ. J. Glass Sci. Technol. A, vol. 48, 2007, no. 1, p13-30). The values ​​shown in Table 1 above indicate that all four target compositions are suitable for fiberization by internal centrifugation.

[0066] To obtain these target compositions, the operator has raw materials, in particular dolomite, sand, sodium carbonate, borax, quicklime, ferrite, potassium, manganese, and recycled rock wool. Three types of rock wool compositions are detailed in Table 2 below.

[0067] [Table 2]

[0068] The target composition is obtained by adjusting the mass percentage (%m) of each raw material as indicated in Table 3 below (with a maximum deviation of 0.2% relative to the target composition for major oxides (i.e., the target is greater than 1% by mass) and a maximum deviation of 0.8% relative to the target composition for minority oxides (i.e., the target is less than 1% by mass)).

[0069] [Table 3]

[0070] Therefore, starting from each of the rock wool compositions 1, 2, and 3, and adding appropriate raw materials thereto, the inventors were able to obtain target compositions of low-alumina wool having a mass concentration of rock fibers in the vitrifiable mixture at 1-20%, while meeting the criteria necessary for fiberization by internal centrifugation. Furthermore, it was demonstrated that the use of rock wool can reduce, or even eliminate, certain CO2-emitting raw materials (e.g., lime and dolomite: 0% in target composition 4 using 4% rock wool) or expensive materials (e.g., feldspar).

[0071] Example 2: High-alumina glass fiber

[0072] Two high-alumina glass wool target compositions, listed in Table 4 below, are selected by the furnace operator.

[0073] [Table 4]

[0074] For these two target compositions, the liquidus temperature (Tliq) and Tlog3 temperature can be determined as shown in Example 1. The values ​​shown in Table 4 above indicate that both target compositions are suitable for fiberization by internal centrifugation.

[0075] To obtain these target compositions, the operator has raw materials, in particular dolomite, bauxite, lime, potash, sand, sodium carbonate, iron oxide, and recycled rock wool. Two types of rock wool compositions are detailed in Table 2 above.

[0076] The mass percentage (%m) of each raw material is adjusted as shown in Table 5 below in order to obtain the target composition.

[0077] [Table 5]

[0078] Therefore, starting from compositions 1 and 2 of rock wool, and adding appropriate raw materials thereto, the inventors were able to obtain a target composition having a mass concentration of rock fibers of 13-37% while satisfying the criteria necessary for fiberization by internal centrifugation.

[0079] Example 3: Economic and energy reduction

[0080] Table 6 below illustrates the reduction in raw materials ("RM") achieved by introducing recycled rock wool, per ton of glass produced (i.e., after melting the raw material composition and before fiberization), for the raw material composition used to obtain target composition 4 (see Table 3).

[0081] [Table 6]

[0082] Using rock wool in the raw material composition for mineral wool production improves material yield. For example, to form 1 ton of molten glass of composition 4 (which becomes mineral wool after fiberization), 1071.3 kg of raw material is required when 4% rock wool is present, compared to 1077.1 kg when rock wool is absent.

[0083] Table 7 below illustrates the reduction in CO2 emissions (range 1) per ton of glass produced, considering the three main factors of CO2 emissions (range 1), for the raw material compositions used to obtain target composition 4 (see Table 3): - Dolomite: CO2 emission factor 0.47t CO2 / t RM, - Sodium carbonate: CO2 emission factor 0.41 t CO2 / t RM, - Quicklime: CO2 emission factor 0.41t CO2 / t RM.

[0084] [Table 7]

[0085] Using rock wool in the raw material composition during the production of mineral wool reduces CO2 emissions (range 1). For example, introducing 1% to 4% rock wool to form the molten glass (which becomes mineral wool after fiberization) of composition 4 reduces CO2 emissions, particularly CO2 (range 1), by 5% to 17%.

Claims

1. A raw material composition suitable for being melted and fibrousized by internal centrifugal separation to obtain mineral wool, characterized in that the raw material composition contains 1% to 50% by mass of recycled rock wool material.

2. The raw material composition according to claim 1, wherein the raw material composition contains at least 2%, preferably at least 5%, of Fe2O3 by mass ratio with respect to the solid content mass in the raw material composition.

3. The raw material composition according to claim 1 or 2, wherein the raw material composition contains at least 2%, preferably at least 5%, of Al2O3 by mass ratio with respect to the solid content mass in the raw material composition.

4. The aforementioned recycled rock wool material comprises the following components by mass percentage: SiO2: 30-50%, Al2O3: 10-22%, CaO + MgO: 20-45%, Fe2O3: 0-20%, for example, 3-20% Na2O+K2O: 0-8%, B2O3: 0-1%. A raw material composition according to any one of claims 1 to 3, having a chemical composition containing the following.

5. The aforementioned recycled rock wool material comprises the following components by mass percentage: SiO2: 30-50%, Al2O3: 10-22%, CaO + MgO: 20-45%, Fe2O3: 3-20%, Na₂O + K₂O: 0-8%, or even 0-5%, B2O3: 0-1%, A raw material composition according to any one of claims 1 to 4, having a chemical composition containing the following.

6. The aforementioned recycled rock wool material comprises the following components by mass percentage: SiO2: 40-48%, Al2O3: 14-19%, CaO + MgO: 24-33%, Fe2O3: 5-12%, Na2O+K2O: 2-4%, B2O3: 0-1%, The raw material composition according to claim 4 or 5, having a chemical composition including the following:

7. A raw material composition according to any one of claims 1 to 6, comprising 1% to 40% by mass of recycled rock wool, for example, 10% to 40%.

8. The aforementioned mineral wool comprises the following components by mass percentage: SiO2: 30-75%, for example, 39-70% Al₂O₃: 0-30%, for example, 1-25% CaO + MgO: 5-45%, for example, 5-18% Fe2O3: 0-20%, for example, 0-10% Na₂O + K₂O: 4-20%, for example, 9-18% B2O3: 0-14%, MnO: 0-4%, A raw material composition according to any one of claims 1 to 7, having a chemical composition including

9. The aforementioned mineral wool comprises the following components by mass percentage: SiO2: 30-75%, Al2O3: 0-30%, CaO + MgO: 5-18%, Fe2O3: 0-20%, Na2O+K2O: 4-20%, B2O3: 0-14%, MnO: 0-4%, A raw material composition according to any one of claims 1 to 7, having a chemical composition including

10. The aforementioned mineral wool comprises the following components by mass percentage: (a) SiO2: 50-75%, for example 60-70%, Al₂O₃: 0-8%, for example, 1-5% CaO + MgO: 5-20%, for example, 9-14% Fe2O3: 0-3%, for example, 0-1% Na₂O + K₂O: 6-20%, for example, 12-18% B2O3: 0-14%, MnO: 0-4%, or (b) SiO2: 35-55%, for example 40-50%, Al₂O₃: 16-27%, for example, 17-25% CaO + MgO: 3-30%, for example, 3-18% Fe2O3: 0-15%, for example, 1-8% Na₂O + K₂O: 5-17%, for example, 7-17%, or even 9-17%, B2O3: 0-5%, for example, 0-2% A raw material composition according to any one of claims 1 to 9, having a chemical composition including

11. The aforementioned mineral wool comprises the following components by mass percentage: SiO2: 30-75%, Al2O3: 16-27%, CaO + MgO: 3-18%, Fe2O3: 0-15%, Na2O+K2O: 9-17%, B2O3: 0-5%, A raw material composition according to any one of claims 1 to 10, having a chemical composition containing the following.

12. A method comprising the step of melting a raw material composition according to any one of claims 1 to 11 in a glass furnace.

13. A method for producing mineral wool, characterized by carrying out the melting method described in claim 12 and a subsequent step of fiberizing the molten composition of raw materials by internal centrifugal separation.

14. Mineral wool obtained by the manufacturing method described in claim 13.

15. Al for the manufacture of mineral wool ２ O ３ The use of recycled rock wool as a source of CaO and MgO.

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