A MOLDED ARTICLE, BINDER SYSTEM AND METHOD FOR PRODUCING A COMPOSITE MATERIAL FROM GLASS WOOL AND STONE WOOL

TECHNICAL FIELD

The disclosure relates to a composite material obtained by processing used glass wool and used stone wool, a method for producing the composite material, a molded article comprising the composite material and to a binder system comprising the composite material.

BACKGROUND

Stone wool is a fibrous material made from the spinning of a 1500 °C melt into fibers. The material is mainly known as an insulation material with excellent fire properties and is a widely used material for building insulation, to provide thermal and acoustic comfort for all types of buildings. Glass wool is another insulating material made from fibers of glass arranged using a binder into a texture similar to wool. The process traps many small pockets of air between the glass, and these small air pockets result in high thermal insulation properties. As there is a growing global focus on limiting energy consumption and the release of greenhouse gasses, the use of building insulation material has been growing. As the use of stone and glass wool grows, so does the amount of wool waste generated either during production and installation or during the renovation and demolition of buildings.

The use of recycled primary raw materials, such as cullet (crushed glass) for glass wool, dramatically improves the carbon footprint of the production process, and secondary raw materials from other industries in stone wool, doubly benefit the environment by minimizing waste and reducing consumption of primary raw materials. In addition, for the purpose of reducing process waste, manufacturing processes have been reengineered to incorporate production scrap back into the primary production process, allowing 75% of glass wool production waste and 66 - 100% of stone wool waste to be recycled.

Material produced before 1997 have a weighted biopersistance of about 17 days, thereby exceeding the limit of 10 days according to CLP Regulation Index 926-099-9: "Synthetic glassy (silicate) fibers without specific orientation and containing more than 18 % by weight of alkaline oxides and alkali earth oxides (Na20 + K2O + CaO + MgO + BaO) .

Biopersistence is influenced by several parameters, including chemical composition.

Materials produced today are produced to meet the requirements of said CLP Regulation Index, however, waste originating from building demolition typically ends up as landfill, where organic binders present in stone and glass wool give rise to methane gas, which has a far greater green-house effect than carbon dioxide.

Further, the flexible nature of glass and stone fibers causes said byproducts to be classified as hazardous to health due to their physical properties.

Recycling solutions existing today are severely limited in capacity and don't solve the aforementioned problems. The origin of the fibers, the presence of organic binder and the hazardous classification are all limitations to establishing alternative recycling solutions. Therefore, a viable outlet for waste generated during the renovation and demolition of buildings is currently lacking.

SUMMARY

It is, therefore, an object to provide a method of treating glass and stone wool waste to obtain a non-hazardous crystalline composite material that can be manipulated safely and/or disposed of in an innocuous manner or used in downstream applications such as production of molded articles useful in construction applications or as a filler.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures .

According to a first aspect, there is provided a method for producing a composite material, said method comprising the steps of:

- providing a fibrous stone wool component comprising fibers and with a stone component crystallization temperature range ,

- providing a fibrous glass wool component comprising fibers and with a glass component melting temperature,

- mixing said fibrous stone and glass fibers to obtain at least one stone and glass fiber cluster, and

- subsequently heating said at least one cluster above the glass component melting temperature and below the stone component upper crystallization temperature limit such that at least some glass fibers melt to form droplets and some stone short fibers undergo crystallization. Thereby, the composite material changes character from a flexible fiber material to a more rigid, brittle material. This is because the glass component at least partially melts and binds/sinters the stone component into small lumps. The partial melting also causes the stone component to transition to a crisp crystalline state, thereby losing the potentially harmful properties.

By maintaining the temperature below the stone component upper crystallization temperature limit, state transition of the stone component to a crystal form is favored; the stone component does not melt, thus, allowing for obtaining a crystal form that sinters with the glass component more readily, and avoids obtaining a melted stone component that mixes with the at least partially melted glass component and forms a solid mixture with porous structure when cooled.

In addition, said method advantageously produces a composite material wherein the sum of Na2O, K2O, CaO, MgO and BaO is above the 18% w/w by which said material may display a biopersistence below 10 days, thereby no longer being classified as hazardous material.

In a possible implementation form of the first aspect, the method comprises the steps of:

- providing a fibrous stone wool component comprising fibers and with a stone component crystallization temperature range ,

- providing a fibrous glass wool component comprising fibers and with a glass component melting temperature,

- mixing said fibrous stone and glass fibers to obtain at least one stone and glass fiber cluster, and - subsequently heating said at least one cluster above the glass component melting temperature and below the stone component upper crystallization temperature limit such that at least some glass fibers melt to form droplets and some stone short fibers undergo crystallization, wherein the stone and/or glass short fibers before mixing are between 0.01mm and 13mm in length, such as between 0.01mm and 10mm in length, such as between 0.1mm and 8mm in length, such as between 0.1mm and 6mm in length, such as between 0.1mm and 4mm in length, such as approximately 2mm in length.

In a possible implementation form of the first aspect at most 60% w/w glass component is provided, such as at most 55% w/w, such as at most 50% w/w, such as at most 45% w/w, such as at most 40% w/w, such as at most 35% w/w, such as at most 30% w/w, such as at most 25% w/w, such as at most 20% w/w, such as at most 15% w/w, such as at most 10% w/w, such as at most 5% w/w, such as at most 3% w/w, such as approximately 1% w/w. By not comprising more than the stated percentage of glass component, the resulting composite material advantageously displays a density that allows for easy manipulation and mixing with additional components for downstream applications. In addition, by not comprising more than the stated percentage of glass component, porous and brittle nature of the composite material is advantageously achieved. By the composite material being brittle, a non-hazardous material and molded article may advantageously be achieved. A brittle composite material also favors physical degradation and incorporation of the same when, e.g. , mixed with other material, such as earth or clay to form a brick.

In a possible implementation form of the first aspect the molded article comprises at most 99% w/w stone component, such as at most 95% w/w stone component, such as at most 90% w/w stone component, such as at most 85% w/w stone component, such as at most 80% w/w stone component, such as at most 75% w/w stone component, such as at most 70% w/w stone component, such as at most 65% w/w stone component, such as at most 60% w/w stone component, such as at most 55% w/w stone component, such as at most 50% w/w stone component, such as at most 45% w/w stone component, such as approximately 40% w/w stone component .

In a possible implementation form of the first aspect stone and/or glass fibers are mixed.

By mixing stone and/or glass fibers a mix comprising stone and/or glass fiber clusters is obtained. Said clusters favor adhesion/ sintering of melted glass to crystallized stone components to obtain a porous and brittle composite material comprising a crystallized stone wool component and a glass wool component, wherein at least part of the glass component acts as a binder in the composite material.

In a possible implementation form of the first aspect stone and/or glass fibers before mixing are no more than 13 mm in length, such as no more than 10mm in length, such as no more than 9mm in length, such as no more than 8mm in length, such as no more than 7mm in length, such as no more than 6mm in length, such as no more than 5mm in length, such as no more than 4mm in length, such as approximately 3mm in length. By the stone and/or glass short fibers not being above the stated length, the number of contact points between melted glass compound and crystallized stone component are advantageously increased. Also, ease of state transition of stone wool short fibers from fibrous to crystalline form, as well as the melting of glass short fibers to form droplets in the mix is advantageously increased.

Thus, in a possible implementation form of the first aspect stone and/or glass short fibers before mixing are between 0.01mm and 13mm in length, such as between 0.01mm and 10mm in length, such as between 0.1mm and 8mm in length, such as between 0.1mm and 6mm in length, such as between 0.1mm and 4mm in length, such as approximately 2mm in length.

Thus, in a possible implementation form of the first aspect the method further comprises the step of reducing the size of said fibrous stone and/or glass wool components, so that when mixed, stone and/or glass fiber clusters wherein the greatest dimension is between 0.01mm and 13mm are obtained.

In a possible implementation form of the first aspect the size reduction of said fibrous stone and/or glass wool components to obtain stone and/or glass fiber clusters wherein the greatest dimension is between 0.01mm and 13mm is done mechanically, such as by mechanical shredding, milling, or crushing .

In a possible implementation form of the first aspect said stone and/or glass fiber clusters are subjected to a size exclusion process. In one possible implementation form, size exclusion cutoff is set to between 3mm and 20mm, such as to between 3mm and 15mm, such as to between 3mm and 13mm, such as to between 4mm and 12mm, such as to between 5mm and 10mm, such as to between 6mm and 8mm, such as to approximately 7mm.

In a possible implementation form of the first aspect subjecting the stone and/or glass fiber clusters to a size exclusion process comprises passing said clusters through a sieve . In a possible implementation form of the first aspect, reducing the size of the fibrous stone and/or glass wool components to obtain stone and/or glass fiber clusters is done concomitantly with subjecting the stone and/or glass fibers to a size exclusion process. Thereby, overall process time for implementing the method may be advantageously reduced .

In a possible implementation form of the first aspect at least 50% w/w _s of stone wool fibers comprised in fiber clusters are between 0.01mm and 13mm in length, such as at least 55% w/w _s , such as at least 60% w/w _s , such as at least 65% w/w _s , such as at least 70% w/w _s , such as at least 75% w/w, such as at least 80% w / w _s , such as at least 85% w/w, such as at least 90% w/w _s , such as at least 95% w/w _s , such as approximately 100% w/w _s , wherein w _s is total stone component weight provided.

In a possible implementation form of the first aspect the mix is heated above the glass component melting temperature. Thereby, at least part of the glass in the mix melts and forms droplets, which bind the stone component to at least partially form the composite material. Upon cooling below the glass component melting temperature, the glass component hardens and binds the stone component crystals and fibers possibly remaining in the composite material. Further, additional components possibly present in the stone and/or glass wool, such as binders, glue or other contaminants, are burnt away thereby contributing to obtaining a composite material that is non-hazardous and can be directly used as a filler or additive in a molded article, such as a brick or tile useful for construction applications, or as a filler in asphalt compositions, thereby acting as a substitute for sand. Further, because of the combination of large surface area and high content of Si and Al the material is expected to advantageously possess pozzolanic properties, which can be utilized in cement and cement-based binder systems including paint, putty mass, filler paste and inorganic sealants. Further, the resulting composite material may be advantageously used as a substitute for clay and sand in Leca nuts or as raw material in production of stone wool, as a water absorbing and water-retaining material suitable for acting as a substrate for plant growth.

The process for obtaining recycled wool according to the possible implementation forms of the first aspect as described herein can be used to obtain an additive useful in steel production, e.g. , for the purpose of replacing calcium carbonate in the production of steel from iron scrap. Recycled mineral wool binds impurities in the molten iron to form a slag, or production waste, which accumulates on the surface of the molten iron and is removed by skimming with the impurities before the steel is cooled.

In a possible implementation form of the first aspect at least 5% w/wg glass fibers melt to form droplets by effect of said heat, such as 10% w/w _g glass fibers melt, such as 20% w/w _g glass fibers melt, such as 30% w/w _g glass fibers melt, such as 40% w/wg glass fibers melt, such as 50% w/w _g glass fibers melt, such as 60% w/w _g glass fibers melt, such as 70% w/w _g glass fibers melt, such as 80% w/w _g glass fibers melt, such as 90% w/wg glass fibers melt, such as 95% w/w _g glass fibers melt, such as approximately 100% w/w _g , wherein w _g is the weight of total glass component present in the heated mix.

In a possible implementation form of the first aspect the mix is heated below the stone component upper crystallization temperature limit. Thereby, crystallization is favored while avoiding melting of the stone component. Crystallization, i.e. , fibrous amorph to crystallized state-transition of the fibrous stone advantageously provides a stone component in a non-hazardous porous and brittle form.

In a possible implementation form of the first aspect at least 5% w/w _s stone fibers crystallize by effect of said heat, such as 10% w/w _s stone fibers crystallize, such as 20% w/w _s stone fibers crystallize, such as 30% w/w _s stone fibers crystallize, such as 40% w/w _s stone fibers crystallize, such as 50% w/w _s stone fibers crystallize, such as 60% w/w _s stone fibers crystallize, such as 70% w/w _s stone fibers crystallize, such as 80% w/w _s stone fibers crystallize, such as 90% w/w _s stone fibers crystallize, such as 95% w/w _s stone fibers crystallize, such as approximately 100% w/w _s , wherein w _s is the weight of total stone component present in the heated mix.

By binding with the melted fraction of the glass component and subsequent cooling below the glass component melting temperature, an innocuous, inert, and non-hazardous porous and brittle composite material that can be safely disposed of or used in downstream applications such as construction applications or as a filler is advantageously obtained.

In a possible implementation form of the first aspect the temperature is between 300°C and 1200°C, such as between 600°C and 1200°C, such as between 700°C and 1200°C, such as between 800°C and 1200°C, such as between 900°C and 1100°C, such as between 900°C and 1100°C, such as at approximately 950°C, 1000°C, 1020°C or 1050°C. Above said lower temperature limit, and in any case above 300°C, contaminants in glass and/or stone wool advantageously burn away, thereby producing a clean composite material.

In a possible implementation form of the first aspect heat is applied as a batch process in a high temperature oven.

In another possible implementation form of the first aspect heat is applied as a continuous process in a rotational furnace .

In a possible implementation form of the first aspect heat can be applied for at least 1 hour, such as for at least 2 hours, such as for at least 5 hours, such as for at least 10 hours, such as for at least 15 hours, such as for approximately 24 hours.

In a possible implementation form of the first aspect the method further comprises the step of adding clay or a hydrous aluminum phyllosilicate to said mix prior to heating. Upon heating to the aforementioned temperature, the stone and/or glass components at least partly advantageously sinter with the clay or hydrous aluminum phyllosilicate providing a composite material with potential for much higher compressive strength. The stone and/or glass components provide comparatively greater strength when sintered with clay or hydrous aluminium phyllosilicates since sand, which is traditionally used, is prone to introducing cracks in the composite material.

In a possible implementation form of the first aspect the clay or hydrous aluminum phyllosilicate is added to between 50% w/w and 99% w/w, such as to between 60% w/w and 98% w/w, such as to between 70% w/w and 97% w/w, such as to between 80% w/w and 96% w/w, such as to between 90% w/w and 95% w/w, such as to approximately 94% w/w. In a possible implementation form of the first aspect the method further comprises the step of molding said composite material into a compact shape. By the composite material being molded into a compact shape, a solid article may be produced characterized by high density and high compressive strength and that is suitable for use in construction applications, such as roofing, pavement, floor tiles or as wall bricks.

In a possible implementation form of the first aspect the compact shape is molded by applying a force of at least / between 2900 and 12600 N/cm2.

In a possible implementation form of the first aspect the molding is extrusion molding, compression molding, injection molding or rotational molding.

In a possible implementation of the first aspect the composite material is still partially melted at the time of molding, i.e. , is not solid, and can easily be molded into the desired shape within the mold.

Further, by the composite material still being at least partially melted, compaction within the mold facilitates binding of the melted glass and the crystallized stone components and clay, if present, while expelling possible air bubbles and providing a molded composite article with improved characteristics, such as improved density and compressive strength .

In a possible implementation of the first aspect a cooling mold is used for the molding step.

According to a second aspect, there is provided a molded article obtained by a method comprising the steps of: - providing a fibrous stone wool component comprising fibers and with a stone component crystallization temperature range ,

- providing a fibrous glass wool component comprising fibers and with a glass component melting temperature,

- mixing said fibrous stone and glass fibers to obtain stone and glass fiber clusters, and subsequently heating said cluster above the glass component melting temperature and below the stone component upper crystallization temperature limit such that at least some glass fibers melt to form droplets and some stone short fibers undergo crystallization, and

- molding said article in by compression molding or sintering .

In a possible implementation of the second aspect the molded article is obtained by any of the methods as described herein.

By compression molding, it is to be understood any process involving a mold into which the composite material is laid and that gives shape to the molded article by compression and possible curing of said composite material.

In a possible implementation of the second aspect the composite material is presented in the mould in a mixture comprising a thermoplastic polymer, thermosetting polymer and/or an inorganic binder, and, optionally, said mixture is cured.

By the article being molded, the composite material is advantageously compacted into a shape to suit any chosen purpose, e.g. , a straight brick, split, soap, wedge, or arch brick, amongst others, pellet, pavement tile, or an indoor floor or wall tile or an outdoor roofing tile.

In a possible implementation of the second aspect the composite material is mixed with a thermoplastic polymer, thermosetting polymer and/or an inorganic binder.

In a possible implementation of the second aspect the density of the molded article is between 0, 6 - 2 g/cm ³ , such as 0, 65

- 0,85 g/cm ³ , such as 0,7 - 0,8 g/cm ³ , such as approximately 0,75 g/cm ³ . Such a range, e.g. , around 0, 6 g/cm ³ , advantageously corresponds to a molded article comprising a thermos-setting polymer, high content of composite material and low pressure applied.

In a possible implementation of the second aspect the density of the molded article is between 0, 9 - 1, 9 g/cm ³ , such as 1,1

- 1,8 g/cm ³ , such as 1,2 - 1,7 g/cm ³ , 1,3 - 1, 6 g/cm ³ , 1, 4 - 1, 6 g/cm ³ , such as approximately 1,5 g/cm ³ . Such a range corresponds to the molded article comprising an inorganic binder, and very high pressure applied.

Density of the molded article is directly proportional to the relative amount of glass component added to the mix for heating. This is particularly the case when other parameters, such as pressure, humidity, shredding method, sieving and dimensions of the original fibers are maintained constant. Density is best related to the relative content of glass component in the high end of the interval. In the middle and lower end, the structure is preserved, and the density is close to constant.

In a possible implementation form of the second aspect the molded article comprises at most 60% glass component, such as at most 55% glass component, such as at most 50% glass component, such as at most 45% glass component, such as at most 40% glass component, such as at most 35% glass component, such as at most 30% glass component, such as at most 25% glass component, such as at most 20% glass component, such as at most 15% glass component, such as at most 10% glass component, such as at most 5% glass component, such as at most 3% glass component, such as approximately 1% glass component. By not comprising more than the stated percentage of glass component, the molded article advantageously. In addition, by not comprising more than the stated percentage of glass component, porous and brittle nature of the composite material in the molded article is advantageously achieved. By the composite material being brittle, a non-hazardous material and molded article is advantageously achieved. A brittle composite material also favors physical degradation and incorporation of the same when, e.g. , mixed with other material, such as earth or clay to form a brick.

In a possible implementation form of the second aspect the molded article comprises at most 99% w/w stone component, such as at most 95% w/w glass component, such as at most 90% w/w glass component, such as at most 85% w/w glass component, such as at most 80% w/w glass component, such as at most 75% w/w glass component, such as at most 70% w/w glass component, such as at most 65% w/w glass component, such as at most 60% w/w glass component, such as at most 55% w/w glass component, such as at most 50% w/w glass component, such as at most 45% w/w glass component, such as approximately 40% w/w glass component .

In a possible implementation of the second aspect the molded article comprises between 35% w/w and 55% w/w SiC>2, 5% w/w and 15% w/w AI2O3, 0% w/w and 2% w/w TiC>2, 1% w/w and 7% w/w Fe2C>3, 7% w/w and 20% w/w CaO, 4% w/w and 10% w/w MgO, 1% w/w and 6% w/w Na2O, and 1% w/w and 6% w/w K2O.

In a possible implementation form of the second aspect the molded article is molded by applying a force of at least / between 2900 and 12600 N/cm2.

According to a third aspect, there is provided a composite material obtained by a method comprising the steps of:

- providing a fibrous stone wool component comprising fibers and with a stone component crystallization temperature range ,

- providing a fibrous glass wool component comprising fibers and with a glass component melting temperature,

- mixing said fibrous stone and glass fibers to obtain stone and glass fiber clusters, and

- subsequently heating said clusters above the glass component melting temperature and below the stone component upper crystallization temperature limit such that at least some glass short fibers melt to form droplets and some stone short fibers undergo crystallization.

In a possible implementation form of the third aspect the method is any one method described herein above.

In a possible implementation form of the third aspect the composite material comprises at most 60% glass component, such as at most 55% glass component, such as at most 50% glass component, such as at most 45% glass component, such as at most 40% glass component, such as at most 35% glass component, such as at most 30% glass component, such as at most 25% glass component, such as at most 20% glass component, such as at most 15% glass component, such as at most 10% glass component, such as at most 5% glass component, such as at most 3% glass component, such as approximately 1% glass component. By not comprising more than the stated percentage of glass component, the composite material advantageously displays a density that allows for easy manipulation and mixing with additional components for downstream applications. In addition, by not comprising more than the stated percentage of glass component, porous and brittle nature of the composite material is advantageously achieved. By the composite material being brittle, a non-hazardous material is advantageously achieved. A brittle composite material also favors degradation and disappearing of the same when, e.g. , mixed with other material, such as earth in a landfill, or clay in a brick.

In a possible implementation form of the third aspect the composite material comprises at most 99% w/w stone component, such as at most 95% w/w glass component, such as at most 90% w/w glass component, such as at most 85% w/w glass component, such as at most 80% w/w glass component, such as at most 75% w/w glass component, such as at most 70% w/w glass component, such as at most 65% w/w glass component, such as at most 60% w/w glass component, such as at most 55% w/w glass component, such as at most 50% w/w glass component, such as at most 45% w/w glass component, such as approximately 40% w/w glass component .

In a possible implementation of the third aspect the composite material comprises between 35% w/w and 55% w/w SiC>2, 5% w/w and 15% w/w AI2O3, 0% w/w and 2% w/w TiC>2, 1% w/w and 7% w/w Fe2C>3, 7% w/w and 20% w/w CaO, 4% w/w and 10% w/w MgO, 1% w/w and 6% w/w Na2O, and 1% w/w and 6% w/w K2O. According to a fourth aspect, there is provided a binder system comprising a composite material obtained by a method comprising the steps of:

- providing a fibrous stone wool component comprising fibers and with a stone component crystallization temperature range ,

- providing a fibrous glass wool component comprising fibers and with a glass component melting temperature,

- mixing said fibrous stone and glass fibers to obtain stone and glass fiber clusters, and

- subsequently heating said clusters above the glass component melting temperature and below the stone component upper crystallization temperature limit such that at least some glass short fibers melt to form droplets and some stone short fibers undergo crystallization,

- grinding, crushing, or milling the composite material, and

- mixing the composite material with a binder, such as cement .

Due to the materials porous and brittle nature, it can easily be milled, grinded or in other ways manipulated to obtain smaller particle sizes, which process advantageously opens a variety of applications such as fine filler material in paint, putty mass and use in a broad range of polymer-based materials .

In a possible implementation form of the fourth aspect the composite material is in the form of fine aggregates, such that mortar suitable for masonry is obtained. Fine aggregates are those comprising composite material particles with no dimension greater than 63pm.

In a possible implementation form of the fourth aspect the composite material is in the form of intermediate aggregates, such that concrete suitable for use as construction material is obtained. Intermediate aggregates are those comprising composite material particles with no dimension greater than 2mm.

In a possible implementation method of the fourth aspect the composite material is in the form of coarse aggregates, such that concrete suitable for use as construction material is obtained. Coarse aggregates are those comprising composite material particles with no dimension greater than 9mm.

In a possible implementation method of the fourth aspect the composite material is mixed with asphalt and thereby used as a filler aggregate helping to fill voids in paving mix and improving cohesion of asphalt binder.

In a possible implementation form of the fourth aspect the binder comprises 50 - 70% w/w calcium silicate.

In a possible implementation form of the fourth aspect the composite material acts as a filler displaying pozzolanic activity for use as filler material in cement, concrete and other calcium-based systems, e.g. , calcium-based paint, calcium-based putty mass and similar.

In a possible implementation form of the fourth aspect the binder is a calcium aluminate cement comprising 10 - 40 % w/w C4AF (C=CaO, A=A12C>3, F=Fe2C>3) and / or 40 - 50% w/w calcium aluminate wherein compressive strength of a concrete 70 x 70 x 280mm prism with at least 250 Kg cement / m3 and 50% w/w water content is more than 5000 Psi after two days at 18°C. In a possible implementation form of the fourth aspect the binder system further comprises amorphous silica and one or more bases.

In a possible implementation form of the fourth aspect the base is a calcium siliconate.

These and other aspects will be apparent from the embodiment ( s ) described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 is a flow chart illustrating an embodiment of a method for producing composite material.

Fig. 2 is an illustration of non-heated glass and stone wool material consisting of fibers.

Fig. 3 is an illustration of a composite material following heat treatment according to the method and comprising glass component droplets and brittle stone crystals.

Fig. 4 is an illustration of composite material following heat treatment of glass and stone components and having been subsequently submitted to light finger pressure.

Fig. 5 is a flow chart illustrating an embodiment of a method for producing a molded composite article.

Fig. 6 is an illustration of composite material obtained according to the method and comprising 97% w/w sintered clay. DETAILED DESCRIPTION

Definitions

Stone and glass components, as referred to herein, may or may not comprise stone or glass fibers. Thus, the term stone and/or glass components may refer to either fibrous stone and glass components in the mix provided for heating or to the glass- and stone-derived composite material resulting from treatment by heat comprising mostly molten or re-solidified glass and crystallized stone, and no or a negligibly low weight percentage of stone and/or glass fibers.

The term "crystallization" as used herein refers to the process through which the atoms and / or molecules of a substance arrange themselves in a well-defined three- dimensional lattice and consequently minimize the overall energy of the system. When a substance is subjected to crystallization, its atoms or molecules bind together through well-defined angles. Thus, crystallization of stone wool fibers involves re-organization of stone wool molecules that form an amorphous fiber into an organized three-dimensional lattice to form stone crystals by the action of applying heat as described in the methods herein.

Compressive strength is tested by measuring the compressive load at which a sample deforms, fractures, shatters, or collapses. This type of test may be applied to a variety of products including glass, stone, bricks, concrete, or any sample where compressive strength is mentioned herein.

As used herein, the term "pozzolanic" refers to materials that are siliceous and aluminous, possessing little or no cementitious value by themselves, but in finely divided form and in the presence of moisture react chemically with calcium hydroxide liberated on hydration of cement at ordinary temperature to form compounds, possessing cementitious properties .

As used herein, the term cluster refers to, at the very least, a loose but discernible grouping of stone wool and/or glass wool material at a higher density than more dispersed surrounding material. Clusters ideally consist of tightly interacting stone wool and/or glass wool material surrounded by little to none lose material.

Referring to the diagrammatic representation of the method in Fig. 1, the composite material 1 is produced from at least a fibrous stone wool component and a fibrous glass wool component. Both components comprise at least 50% clusters of fibers wherein the greatest dimension is between 3mm and 13mm. This size ensures optimal mixing (B, D) and, once the glass component is melted and the stone component at least partly crystallized, optimal mixing and embedding of the stone crystals within the glass droplets.

If the components do not already conform to these dimensions, a size reduction step (A, B, C) is carried out. This may consist in crushing, milling, applying vibration, pulling, shredding or otherwise mechanically stressing the fibers to obtain fibers of the stated length. Size reduction by shredding is typically performed on a fast or semi fast running shredder or a fast or semi fast running hammer mill with a speed of 20-120 RPM, typically 20-40 RPM or 70-80 RPM. The shredder can be a single shaft or double shaft equipped with a screen of size 10mm - 40mm for size-exclusion. Alternatively, the size reduction can be carried out by milling in a ball mill or a rod mill, with typical running speed between 10-20 RPM.

A subsequent, or concomitant size-exclusion step (A, B, C) may be also carried out. Size-exclusion can be performed on a drum sieve, flip-flop screen or vibrating screen.

Screen size is typically 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm, 12mm, 15mm or 20mm sieve. This results in a more homogeneous collection of fibers and further improved mixing and embedding of said fibers.

A step of mixing said fiber may be carried out as a separate step (A, B) in a dedicated mixing device or might be omitted (C) if the fibers are already mixed to a satisfactory degree after size-reduction and size-exclusion.

In some cases, the process of mixing will be sufficient for obtaining fibers of the desired length, thus, dedicated sizereduction and size-exclusion step may be omitted (D) .

Once a satisfactory mix of stone and glass components is obtained, this may proceed to being heated in an oven. Glass component melting temperature will previously have been established, and will determine the lower temperature range limit, as it is paramount for the process that at least some of the glass component melts to form droplets in the mix that first bind and then embed the crystallized stone component.

The stone component has a crystallization temperature range, i.e. , a range of temperatures at which the stone component transitions from an amorphous, fibrous state to a crystalline state . Temperature in the oven is set to below the upper stone component crystallization temperature limit. This ensures that while favoring amorphous to crystal transition, the stone component is not heated to its combustion temperature.

Thus, temperature in the oven is set to a temperature falling within the range delimited by the glass component melting temperature on the lower end and the upper stone component crystallization temperature limit on the upper end. Such a temperature lies between 500°C and 1200°C, such as at approximately 950°C, 1000°C, 1020°C or 1050°C.

Thermal treatment can be executed as a batch process in a high temperature oven, or as a continuous process in a rotational furnace.

Fig. 2 illustrates non-heated glass (3) and stone wool (4) fibers, which are flexible in nature and thereby constitute a health hazard for an operator when manipulating waste comprising them or for potential end-users of products comprising them.

Fig. 3 illustrates a composite material following heat treatment according to the method and comprising glass component droplets (5) and brittle stone crystals (6) . The heat-treated sample of composite material appears as small lumps of glass and stone component that have fused together (5, 6) . The material is also whitish in color, indicating that it has been partially melted and crystalline. By the material having fused together, it is no longer made up of individual fibers. The lighter color also shows that the material has changed from a flexible fiber material to a crisp crystalline material, with fundamentally different chemical and physical properties, rendering the composite safe and non-hazardous to health.

The product is a brittle porous non-fibrous material that easily breaks up to a sand-like material with a typical particle size 0-2mm, as illustrated in Fig. 4. Light mechanical pressure causes the material to crumble, which shows that it is no longer a flexible fiber material, but rather a brittle crystalline material. To some degree the geometrical shape from the fibrous starting material is preserved in the product, which results in a very high surface area. With further rubbing, the small angular crystals (6) break down further, mimicking the expected effect of mixing the composite material with additional material, such as earth and/or disposing of the composite material in a landfill.

Turning now to the diagrammatic representation of the method in Fig. 5, the composite article 2 is produced from at least a fibrous stone wool component and a fibrous glass wool component submitted to a heat treatment and with the same optional prior steps A, B, C, D as for production of the composite material 1. In addition, composite material 1 is introduced into a mold wherein compaction is achieved by applying pressure to the composite material and results in a molded composite article 2. Such a mold is arranged to produce bricks for use in masonry, floor or roofing tiles, pavement tiles and the like for use in construction applications by compression molding.

In another example of implementation of the method for producing a composite article, between 90% w/w and 98% w/w clay or hydrous aluminum phyllosilicate is added to the mix prior to heating. Thus, clay or hydrous aluminum phyllosilicate may be added prior to mixing, prior to size reducing and/or submitting the mix to a size-exclusion process, or directly before heating the mix.

In addition to glass and stone components 3, 4 changing the character by being submitted to heat-treatment, composite material is sintered with clay as shown in Fig. 6 when the two components are mixed and heat-treated as in Fig. 5. This integrates, at least in part due to sintering, the composite material as an integral part of the heated clay. The composite material thus ceases to exist as an independent material. Even when molded article 1, such as a brick or Leca® nuts are crushed and reused after use, no fibers will be released from these materials. Glass and stone components and clay sinter together. However, there is no trace of fiber-like materials that can be released from the material. All mineral components and clay are sintered together in a dead-burned mass of silicates .

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed sub ect-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage . The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g. , cross-hatching, arrangement of parts, proportion, degree, etc. ) together with the specification, and are to be considered a portion of the entire written description of this disclosure.

Example 1

Composite material chemical composition Ratios between glasswool stone wool and other A12O3 and SIO2 based mineralwool Example 2

Composite material chemical composition