Recycling floor covering materials

Abstract

A method of recycling floor covering material having a backing layer comprising a backing material. The method comprises a cooling step to reduce the temperature of the floor covering material, follow

Description

The present invention relates to a method and apparatus for recycling floor covering materials and is concerned in 5 particular, though not exclusively, with a method and apparatus for recycling floor covering materials comprising Bitumen. A typical floor covering material comprises at least an 10 upper layer of face yarn or a fibre as a pile, and one or more support layers including a backing. Bitumen is often used in the backing material as it is stable and resilient. However, the presence of bitumen makes it difficult to recycle the floor covering materials at the end of their 15 useful life, as it causes shredding machines, often used in the recycling of textiles, to become clogged. A typical floor covering material backing is usually comprised of a mixture of bitumen and calcium carbonate. 20 As a result, floor covering materials are usually disposed of by either incineration or placing in landfill. Neither of these solutions is good for the environment. Incineration of floor covering materials can release harmful chemicals and significant amounts of carbon into 25 the atmosphere. Floor covering materials that end up in landfill will likely take decades to degrade and will remain, while leaching chemicals such as dyes into the ground. 30 Therefore, there is a need for disposing of floor covering materials, especially those that comprise Bitumen, that is environmentally friendly and scalable. Embodiments of the present invention aim to provide a method of recycling floor covering materials wherein the aforementioned problems are addressed. The present invention is defined in the attached independent claims, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto. According to one aspect of the present invention, there is provided a method of recycling a floor covering material having a backing layer comprising a backing material, the method comprising a cooling step of substantially reducing the temperature of the floor covering material, followed by a size reduction step comprising mechanically fragmenting the floor covering material, and wherein the method comprises combining the size-reduced floor covering material with new backing material to form a backing layer for new floor covering material. The floor covering material preferably comprises tiles, such as carpet tiles, more preferably bitumen-backed tiles. Preferably, portions of the floor covering material are sorted according to origin prior to the step of substantially reducing the temperature of the floor covering material. The size reduction step may comprise inputting the floor covering material into a size-reduction apparatus, comprising one or more of a shredder, a cutting device, a chopping device a grinder and / or a guillotine. The size reduction step may comprise any of pulverizing, grinding, cutting, chopping, impacting, shocking, for example acoustically shocking, shearing, ultrasonically vibrating and / or comminuting the floor covering material. The size reduction apparatus may comprise brushes to remove any residue left from the size reduction process. These brushes may comprise bristle brushes. Preferably, there is at least a first and a second size reduction step. The first size reduction step may comprise reducing the size of the floor covering material into particles between 10mm - 5mm. The second size reduction step may comprise further size reduction of the floor covering material into particles between 5mm - 1mm. By using two size reduction steps to obtain a required particle size, overheating of the floor covering material can be avoided. Optionally, there is a further cooling step between the first and second size reduction steps. Optionally, there is a further size reduction step whereby the floor covering material obtained from either the first or second size reduction step is ground into a powder having a particle size of less than 1mm. Optionally there is a further cooling step before the further size reduction step . Preferably the floor covering particle size in a range preferably, the floor covering particle size in a range of preferably, the floor covering particle size in a range of 200 material is fragmented to a of 1-1000 microns. More material is fragmented to a 100-750 microns. Still more material is fragmented to a -500 microns. The floor covering material may be transported along a vibrating conveyor apparatus between steps. This advantageously allows the material to spread out and lie substantially level. The fragmented floor covering material may be screened by size, preferably using a sieve. More preferably, the fragmented floor covering may be sorted by size using a micron sieve. The fragmented floor covering material may have its moisture content reduced. Preferably, the fragmented floor covering has its moisture content reduced in a dehumidifier. This may occur at any point after the temperature of the floor covering material has been substantially reduced. The fragmented floor covering may be collected and stored. The fragmented floor covering may be recycled to make further floor covering material. This further floor covering material may comprise floor covering material backing. The cooling step of the method may include reducing the temperature of the floor covering material by exposing it to a cooling component, such as to a liquefied gas, such as (but not limited to) liquid nitrogen. The method may include cooling the floor covering material within a temperature range of -50°C and -10°C at atmospheric pressure. The cooling component may be applied to the floor covering material by spraying the cooling component onto the material. Alternatively, or in addition, the cooling component may be applied to the floor covering material by pouring the cooling component onto the floor covering material. Alternatively, or in addition, the cooling component may be applied to the floor covering material by at least partially immersing the material in a volume of cooling component. Alternatively, or in addition, a cooling component may be applied to the size reduction apparatus. Alternatively, or in addition, the cooling step of the method may include reducing the temperature of the floor covering material by exposing the floor covering material to a cooled environment. The cooled environment may comprise a freezer. The cooled environment may be within the temperature range of -10°C to -20°C. The method may comprise the step of monitoring the temperature of the size reduction apparatus and controlling the rate of input of the floor covering material according to the monitored temperature. Preferably, the apparatus is kept at a temperature range of 0-110°C.More preferably, the apparatus is kept at a temperature range of 40-90°C. Even more preferably, the apparatus may be kept at a temperature range 70-90°C. The rate of the input of the floor covering material may be constantly adjusted to keep the temperature of the apparatus within the preferred temperature range. The recycling method may include the step of combining the fragmented floor covering material as a feedstock material into a backing material in the process of making a new floor covering material. In a preferred arrangement, the recycling method may comprise replacing at least some of 5 the bitumen and / or calcium carbonate in a backing material with the fragmented floor covering material. According to another aspect of the present invention, there is provided an apparatus for facilitating the recycling of 10 a floor covering material, the apparatus comprising a cooling stage wherein the temperature of the floor covering material is substantially reduced, and a size reduction stage, wherein the temperature-reduced floor covering 15 material is mechanically fragmented. The apparatus may comprise a preliminary stage wherein the floor covering material is reduced in size. The apparatus may comprise a size reduction apparatus comprising one or more of a shredder, a cutting device, a chopping device, 20 grinder and / or a guillotine. The size reduction apparatus may be arranged in use to fragment the floor covering using any of: pulverizing, grinding, cutting, chopping, impacting, shocking, for example acoustically shocking, shearing, ultrasonically vibrating and / or comminuting the 25 floor covering material. The size reduction device may comprise brushes to remove any residue left from the size reduction process. These brushes may comprise bristle brushes . 30 The apparatus may comprise a stage where the fragmented floor covering material is screened by size, preferably using a sieve. More preferably, the fragmented floor covering may be screened by size using a micron sieve. The apparatus may comprise a coolant applicator for applying a cooling component to the floor covering material. The coolant applicator may be arranged in use to spray the floor covering material with a cooling component. The apparatus may include a temperature monitor arranged in use to measure the temperature of the apparatus. The monitor may be arranged in use to produce a signal when a preferred temperature range has been exceeded. The apparatus is preferably arranged in use to control a rate of input of the floor covering material based on the temperature of the apparatus. According to another aspect of the invention, there is provided a method of recycling a floor covering material having a backing layer comprising a backing material, the method comprising a size reduction step of mechanically fragmenting the floor covering material using size reduction apparatus, and wherein the method comprises monitoring the temperature of the size reduction apparatus and controlling a rate of input of the floor covering material according to the temperature of the size-reduction apparatus, and wherein the method further comprises combining the size-reduced floor covering material with new backing material to form a backing layer for new floor covering material. The floor covering material preferably comprises tiles, such as carpet tiles, more preferably bitumen-backed tiles. Preferably, the apparatus is kept at a temperature range of 0-110°C. More preferably, the apparatus may be kept at a temperature range of 40-90°C. Even more preferably, the apparatus may be kept at a temperature range 70-90°C. The rate of the input of the floor covering material may be constantly adjusted to keep the temperature of the 5 apparatus within the preferred temperature range. According to another aspect of the present invention, there is provided a carpet tile including a backing layer of backing material, wherein the backing material comprises a 10 portion of previously made, entire fragmented carpet tile. The backing material may include a portion of recycled entire carpet tile in the range l%-50%, more preferably 5%-20% . 15 The invention also includes a floor covering material made using a recycled product according to any statement herein. Where the term "bitumen" is used herein, this should be 20 taken to include natural or modified bitumen, or a combination thereof. The invention may include any combination of the features or limitations referred to herein, except such a 25 combination of features as are mutually exclusive, or mutually inconsistent. A preferred embodiment of the present invention will now be described, by way of example only, with reference to the 30 accompanying diagrammatic drawings, in which: Figure 1 is a schematic representation of an apparatus for recycling floor covering materials, in accordance with an embodiment of the present invention; Figure 2 shows schematically a method of recycling a floor covering material according to an embodiment of the present 5 invention; and Figure 3 shows schematically a method of recycling a floor covering material according to a further embodiment of the present invention. 10 Turning to Figure 1, this represents schematically, generally at 1000, an apparatus for carrying out the recycling of floor covering materials according to an embodiment of the present invention. In this case the floor 15 covering materials are carpet tiles of an approximate size of 500 mm x 500 mm and 5 mm thickness, having a backing that is bitumen-based, that are at the end of their useful life. Other examples of floor covering material that could be used include, but are not limited to; chips, planks, and 20 factory waste cut offs. The tiles 1100 are received and sorted (not shown) and then introduced via a conveyor 1300 into a first size reduction apparatus 1150. The size reduction apparatus 1150 reduces 25 the size of the tiles into pieces of approximately 6mm x 6mm. The size reduction apparatus may include a chopper, grinder, shredder or similar, and is brushed with bristle brushes (not shown) at regular intervals to reduce clogging of the apparatus from the tiles. The reduced sized tiles 30 1100a enter a hopper 1200 from which they are deposited on a conveyor 1310. The conveyor 1310 vibrates such that the reduced sized tiles 1100a spread out and lie substantially level on the conveyor 1310. The tiles 1100a are then carried into a cooling bay 1400 in which they are exposed to a cooling component, such as liquid Nitrogen from spray nozzles 1410 until the tiles become sufficiently cooled so as to render them frangible, friable or brittle. The tiles leave the cooling bay 1400 and are transported through hopper 1200 to a second size reduction apparatus, in this case press 1500 where they are pulverized 1500, to break up the brittle carpet tiles into small particles of the order of 0.2 - 0.5 mm. As an alternative to a press, the second size reduction apparatus could be a grinder or similar. The pulverized carpet tile material 1100b travels on a further conveyor 1320 and is screened at 1600 such that material which is considered too big to use is screened out. Any pieces that are too big are returned to the press to be further pulverized, as shown by arrow A. The fragmented tile material 1100b is then transported on a further conveyor 1330 which vibrates such that the material 1100b spreads out and lies substantially level on the conveyor 1330. The conveyor 1330 transports the tile material 1100b to a dehumidifier 1700 where it is dried and then collected in a container 1800. The collected material 1100b is then added back into production to form part of a suitable backing material for new carpet tiles. Figure 2 shows schematically, generally at 2000, a method of recycling floor covering materials in accordance with the embodiment of the present invention described above. The floor covering materials, which in this example are used carpet tiles at the end of their useful life, are received at a Step 3100. They may then be sent to be reduced in size to approximately 6mm x 6mm at a size 5 reduction step 3200. If the floor covering material is received in a sufficiently small size, Step 3200 may be omitted. These reduced size tiles are then cooled, by exposure to / immersion in liquid nitrogen at a cooling Step 3300. Treatment by the liquid nitrogen cools the tiles to 10 the point at which they become brittle. This step may, effectively, freeze the articles. They are then transported to a fragmentation Step 3400, in which the carpet tiles are mechanically fragmented, by one 15 or more of pulverizing, grinding, cutting, chopping, impacting, shocking, for example acoustically shocking, shearing, ultrasonically vibrating and / or comminuting the floor covering material. 20 Fragmentation produces a granular material, with particles being of the order of a few mm or even sub-mm. The granular material may be screened by size, for example using a micron sieve at a step 3500. If the screening 25 process is not necessary, Step 3500 may be omitted. Particles of material that are screened out because they are too large may be returned to step 3400. 30 The screened granular material is dried at a step 3600 by means of a dehumidifier, from which the dried granular material is collected. If the screened granular material does not require drying, step 3600 may be omitted. This material can then be combined at Step 3700 with bitumen and calcium carbonate material for use in the making 3800 . to make a suitable backing of new carpet tiles, in Step Figure 3 shows schematically, generally at 5000, a method of recycling floor covering materials in accordance with a further embodiment of the present invention as described above . The floor covering material to be processed / recycled, which in this example includes used carpet tiles at the end of their useful life, and / or carpet tile production waste such as offcuts and / or scrap material, is received at a Step 5100. The material may be cooled at an optional cooling stage Cl. It is then inputted at stage II into a size reduction apparatus, which reduces the size of the material at a step 5200 by one or more of pulverizing, grinding, cutting, chopping, impacting, shocking, for example acoustically shocking, shearing, ultrasonically vibrating and / or comminuting the floor covering material. The input rate of the floor covering material may be manually or automatically controlled. The temperature of the size reduction machine may be monitored during the mechanical fragmentation as shown at step 5400a and may be used to control the rate of input of material to the size reduction machine . After this first size reduction step at step 5200, the material may be cooled at optional cooling stage C2. The material is then input at stage 12 into a mechanical fragmentation step 5300. The temperature of the size reduction machine may be monitored during the mechanical fragmentation as shown at step 5400b and the rate of input of material is controlled accordingly. Temperature data from step 5400b is fed back to the input step 12. If the temperature of the size reduction apparatus exceeds a predetermined temperature range, the input rate of the floor covering materials may need to be reduced to allow the size reduction apparatus to operate within a predetermined optimal temperature range. Optionally the size reduction apparatus may be cooled at a cooling stage 03. Fragmentation produces a granular material, with particles being of the order of a few mm or even sub-mm. The granular material may be screened by size, for example using a micron sieve at a step 5500. The mechanical fragmentation step 5300 may include a combination of shredding and grinding. For example, there may be at least a first shredding step and more preferably an additional second shredding step. There may be a grinding step, as an alternative or in addition to the or each shredding step, and more preferably following the first shredding step. A material cooling stage preferably cools the material prior to and / or between fragmentation steps. Alternatively, or in addition, there may be an apparatus cooling stage in which the fragmentation apparatus, or at least a part thereof, is cooled for example by the application of a cooling component such as a liquefied gas (e.g. Nitrogen or similar). Particles of material that are screened out because they are too large may be returned to step 5300. In another embodiment, the mechanical fragmentation stage 5300 comprises more than one fragmentation step wherein different screen sizes are used to incrementally reduce the size of the floor covering materials. The screened granular material is dried at a step 5600 by means of a dehumidifier from which the dried granular material is collected. The dried granular material is optionally packaged and stored at step 5700. Preferably, the material is packaged and stored in a way which reduces caking of the material, such as, but not limited to, in thin layers. If this step is not required, then step 5700 may be omitted. The dried granular material can then be combined at Step 5800 with bitumen and calcium carbonate to make a suitable backing material for use in the making of new carpet tiles, in Step 5900. The invention allows the useful recycling of floor covering materials without resorting to landfill or incineration, with their negative environmental impacts. Some previous attempts have been made to recycle carpet tiles, by separating the backing from the yarn. This requires extensive processing of the tiles which is energy intensive and environmentally damaging. In comparison, the present invention offers an efficient, pragmatic and environmentally friendly way of recycling carpet tiles. The present invention provides a method and apparatus for recycling a previously made floor covering material having a backing layer comprising a backing material, the method comprising a cooling step of substantially reducing the temperature of the previously made floor covering material, followed by a size reduction step comprising mechanically fragmenting the previously made floor covering material, and wherein the method comprises combining the size-reduced previously made floor covering material with new (fresh / previously unused) backing material to form a new backing layer for new floor covering material. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and / or shown in the drawings, whether or not particular emphasis has been placed thereon.

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