Synthetic wood incineration and recycling method

Abstract

To provide an incineration method capable of efficiently incinerating synthetic wood.SOLUTION: An incineration method for synthetic wood that comprises fiber-reinforced plastic containing a glass fiber material and has a maximum size of over 1.5 m includes: a first step of cutting the synthetic wood to cut pieces of a length of 1.5 m or less; and a second step of incinerating the cut pieces at 600°C-1200°C for 2-6 hours to obtain glass fiber material-containing incineration residue. The ignition loss of the incineration residue is less than 10%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for incinerating and recycling synthetic wood. [Background technology]

[0002] Synthetic wood is used in various fields as a substitute for natural wood due to reasons such as cost and ease of maintenance. For example, a large amount of synthetic sleepers are required to lay structures such as railways. Natural sleepers made from natural wood were used as sleepers, but nowadays, those made from fiber-reinforced plastics (FRP) are widely used as a substitute for natural sleepers because they do not need to worry about corrosion caused by rain or termites and are easy to maintain.

[0003] However, various FRP products, including synthetic sleepers, contain glass fibers as a reinforcing material, so that when they become waste, they are more difficult to dispose of than natural sleepers. Patent Document 1 (JP Patent Publication 10-085704) proposes a method for disposing of FRP waste in which the FRP waste is heated in an incinerator to oxidize and remove organic matter, and then immediately put into a short glass fiber raw material melting furnace or a rock wool raw material melting furnace. It is disclosed that this method has the advantage that the FRP waste can be used as a raw material for short glass fiber or rock wool, and that industrial waste is reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-085704 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the processing method disclosed in Patent Document 1 can be applied to small-volume items such as scraps, offcuts, and crushed FRP products, some synthetic wood is large in size, and most synthetic sleepers in particular are 2.6 m or longer, making it difficult to process them as is. In addition, even if synthetic wood is incinerated to remove the organic matter, long glass fibers tend to remain, and these glass fibers tend to scatter and have sharp tips, which causes problems in terms of workability and work safety.

[0006] The present invention has been completed in view of the above problems, and in one embodiment, it is an object of the present invention to provide an incineration method capable of efficiently incinerating synthetic wood. In another embodiment, it is an object of the present invention to provide a recycling method that efficiently incinerates synthetic wood and is suitable for the composition of the incineration residue. [Means for solving the problem]

[0007] As a result of intensive research, the inventors have found that by cutting synthetic wood into pieces of a predetermined size or less and then incinerating it under predetermined conditions, the synthetic wood can be efficiently incinerated, thereby solving the above-mentioned problems. The present invention has been completed based on the above findings, and is exemplified below.

[0008] [1] A method for incinerating synthetic wood having a maximum dimension exceeding 1.5 m, the method comprising the steps of: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; a second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing a glass fiber material; wherein the ignition loss of the incineration residue is less than 10%. [2] The incineration method according to [1], characterized in that in the second step, at least a portion of the glass fiber material is melted and solidified to form an integrated glass fiber bundle. [3] The incineration method according to [1] or [2], wherein the incineration residue contains 40 mass% or more of silicon dioxide in terms of oxide. [4] The incineration method according to any one of [1] to [3], wherein the synthetic wood is a synthetic sleeper. [5] The incineration method described in [4], characterized in that in the second step, the pieces are incinerated while being stacked in a tower-like configuration in an incinerator. [6] The incineration method according to [4] or [5], wherein the dimensions of the synthetic sleepers are a length of 2.5 m to 5.0 m, a width of 0.1 m to 0.4 m, and a thickness of 0.1 m to 0.4 m. [7] A method for recycling synthetic wood having a maximum dimension exceeding 1.5 m, which is made of fiber-reinforced plastic containing glass fiber material, comprising: The method comprises: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; A second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing a glass fiber material, At least a portion of the incineration residue is used as a solvent for slag; The recycling method according to claim 1, wherein the incineration residue contains 40 mass % or more of silicon dioxide calculated as an oxide. [8] A method for recycling synthetic wood having a maximum dimension exceeding 1.5 m, which is made of fiber-reinforced plastic containing glass fiber material, comprising: The method comprises: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; A second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing a glass fiber material, At least a part of the incineration residue is used as a raw material for cement, The recycling method according to claim 1, wherein the incineration residue contains 40 mass % or more of silicon dioxide calculated as an oxide. [9] The recycling method according to [7] or [8], characterized in that in the second step, at least a portion of the glass fiber material is melted and solidified to form an integrated glass fiber bundle.

[10] The recycling method according to any one of [7] to [9], wherein the synthetic wood is a synthetic sleeper. Effect of the Invention

[0009] According to one embodiment of the present invention, it is possible to provide an incineration method capable of efficiently incinerating synthetic wood. Also, according to another embodiment of the present invention, it is possible to provide a recycling method capable of efficiently incinerating synthetic wood and suitable for the composition of the incineration residue. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a photograph showing multiple pieces of synthetic sleepers arranged in a tower-like configuration. [Diagram 2] Figure 2 is a photograph showing the state of some of the incineration residue after multiple pieces of synthetic sleepers were assembled into a tower-like structure and incinerated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present invention will be described in detail with reference to the drawings. It should be understood that the present invention is not limited to the following embodiment, and that appropriate changes and improvements in the design may be made based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention.

[0012] (1.Synthetic wood) The synthetic wood that is the subject of the incineration and recycling methods of the present invention is made of fiber-reinforced plastic containing glass fiber material and has a maximum dimension exceeding 1.5 m. The maximum dimension refers to the longest dimension among the dimensions in any direction. Typically, the synthetic wood is a synthetic sleeper for a railway. The dimensions of the synthetic sleeper vary depending on the application, but the typical dimensions of the synthetic sleeper are in the range of 2.5 m to 5.0 m in length, 0.1 m to 0.4 m in width, and 0.1 m to 0.4 m in thickness. As described later, since the synthetic sleeper is long, it is necessary to cut it in the length direction at least once in order to incinerate it sufficiently, but it is also possible to incinerate it without cutting it in the width direction and thickness direction.

[0013] Synthetic wood includes synthetic resin and glass fiber material. Synthetic wood includes, for example, 40% or more synthetic resin. As the synthetic resin, for example, rigid foamed urethane resin such as polymethylene polyphenyl polyisocyanate polyol compound can be mentioned. The glass fiber material in the synthetic wood preferably includes 40% or more by mass of silicon dioxide in oxide equivalent. There is no particular upper limit to the amount of silicon contained in the glass fiber material in the synthetic wood, but for example, it can include 60% or less by mass of silicon dioxide in oxide equivalent. The amount of silicon dioxide contained in the glass fiber material is measured from the incineration residue obtained by incineration by the incineration treatment method of the present invention, as described later. As the glass fiber material suitable for the use of synthetic wood, for example, long fiber glass such as alkali-free glass (E glass, S glass) and alkali-containing glass (C glass, D glass) can be mentioned.

[0014] (2. Method of incineration of synthetic wood) In one embodiment, the synthetic wood incineration method of the present invention includes a first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less. As described above, synthetic sleepers are long, such as 2.5 m to 5.0 m in length, so if they are incinerated as is, it is difficult to completely burn the organic components, which are synthetic resins, and incineration is likely to be insufficient, especially near the center in the length direction. In addition, there is a problem that the incineration residue containing glass fibers after incineration becomes too long, making it difficult to work. Therefore, it is necessary to cut the synthetic wood into pieces with a maximum dimension of 1.5 m or less, preferably 1.4 m or less, and more preferably 1.3 m or less. In the case of synthetic sleepers, since they are long, they are cut to a shorter length.

[0015] From the viewpoint of sufficiently burning the organic components of the synthetic resin, it is preferable to cut the synthetic wood into pieces of shorter length, but cutting into pieces of excessively short length increases the number of times the synthetic wood is cut in the first step, which is not preferable in terms of work efficiency. Therefore, the synthetic wood may be cut into pieces of a maximum dimension of 0.3 m or more, preferably 0.5 m or more.

[0016] On the other hand, synthetic sleepers have relatively small dimensions in the width and thickness directions, so they can be incinerated without being cut. However, smaller pieces are preferred from the viewpoint of sufficiently burning the organic components of the synthetic sleepers. For this reason, the pieces of synthetic sleepers can be further cut in half in the width or thickness directions.

[0017] Next, the second step is carried out in which the pieces obtained by cutting are incinerated at a temperature of 600°C to 1200°C for 2 to 6 hours. If the incineration temperature is lower than 600°C, the organic components of the synthetic wood cannot be sufficiently burned, and the ignition loss described below cannot be achieved. In addition, as described below, a high incineration temperature of 600°C or more is required to melt and solidify the glass fiber material in the incineration residue obtained by incineration to form an integrated glass fiber bundle. From this viewpoint, the incineration temperature is preferably 700°C or higher, and more preferably 800°C or higher. On the other hand, even if the incineration temperature exceeds 1200°C, the effect will plateau, so the upper limit is set to 1200°C from the viewpoint of productivity and cost. The upper limit of the incineration temperature can also be 1100°C or lower, or 1000°C or lower.

[0018] If the incineration time is less than 2 hours, the organic matter in the synthetic wood cannot be sufficiently burned, and the ignition loss described below cannot be achieved. On the other hand, if the incineration time exceeds 6 hours, the effect will reach a plateau, so the upper limit is set to 6 hours from the viewpoint of productivity and cost. The upper limit of the incineration time can also be set to 5 hours or less.

[0019] For the incineration in the second step, an incinerator that incinerates the target object by flame, such as a fixed bed incinerator, can be used. In the case of synthetic sleepers, in the second step, multiple pieces of synthetic sleepers may be incinerated in a state where they are spread out flat in the incinerator, but from the viewpoint of saving space inside the incinerator, multiple pieces may be incinerated in a state where they are assembled and placed in a tower shape. By assembling them three-dimensionally, an air passage can be secured compared to when they are placed in contact with the floor surface, and incineration can be performed more efficiently. The number of layers or height to which the pieces are stacked can be appropriately set according to the dimensions of the pieces and the dimensions of the incinerator.

[0020] In addition, when multiple pieces are assembled in a tower-like shape in the second step, a support may be provided to surround the sides of the tower so that the pieces stacked in a tower-like shape do not fall over during incineration. For example, a metal cage with a mesh-like surface surrounding the sides of the tower may be used as this support. By forming the cage in a mesh shape, the flame of the incinerator can directly contact the pieces through the mesh, allowing for more efficient incineration.

[0021] The second step produces an incineration residue containing glass fiber material. The incineration residue can be disposed of as industrial waste or reused as, for example, a slag solvent as described below. To be disposed of as industrial waste, the incineration residue must have an ignition loss of less than 10%. There is no need to set a lower limit for the ignition loss, but an appropriate lower limit for practical operation may be set, for example, to 4.0% or more.

[0022] Ignition loss (or ignition loss) is measured according to the method described in Attachment 2 of "Points to Note in Guidance for General Waste Treatment Businesses" (Ensei No. 95), issued on November 4, 1977. Specifically, the incineration residue is thoroughly dried at 105°C ± 5°C using a dryer or similar device, and then ignited in an electric furnace at 600°C ± 25°C for three hours. The weight loss rate of the incineration residue after these operations is defined as the ignition loss.

[0023] From the viewpoint of easy handling of the incineration residue, it is preferable that in the second step, at least a part of the glass fiber material of the synthetic wood is melted and solidified to form a glass fiber bundle in which a plurality of glass fibers are integrated. Since each glass fiber is a thin fibrous fiber, it is usually easy to scatter, but by forming a glass fiber bundle, it becomes difficult to scatter, improving workability and work safety. Since glass fibers do not naturally adhere to each other and form bundles, if the formation of a glass fiber bundle is confirmed, it can be considered that the glass fibers have melted and solidified.

[0024] (3. How to recycle synthetic wood) One embodiment of the synthetic wood recycling method of the present invention includes using at least a portion of the incineration residue obtained by any of the embodiments of the synthetic wood incineration method of the present invention as a slag solvent.

[0025] Slag refers to a mixture that is generated by the action of a solvent when melting and refining industrial waste, ores, etc. For example, when processing industrial waste such as incineration ash containing metallic iron, sludge, slag, printed circuit boards, pad scraps, waste catalysts, metal scraps, waste shot, grinding chips, and dust, there is a method of melting industrial waste in which the industrial waste is put into the melting hearth of a reverberatory furnace-type recycling furnace, and the resulting molten material is poured into a basin and separated into slag and matte.

[0026] In order to efficiently separate the slag and matte obtained by the above melting process, it is necessary to melt the high melting point melt into a low melting point slag. For example, iron oxide (Fe 3+ Slag with a high iron content can be converted into metallic iron slag by the following reaction: Fe+Fe2O3→3FeO 2FeO+SiO2 → 2FeO SiO2

[0027] Therefore, a SiO2 source is needed as a flux to lower the melting point of the slag in the recycle furnace.

[0028] In addition to the above-mentioned recycling furnaces for the treatment of industrial waste, non-ferrous smelting furnaces also require a SiO2 source as a slag solvent. For example, copper smelting furnaces include flash furnaces, which oxidize copper concentrate to produce copper matte with a copper content of about 65% and slag mainly composed of Fe and Si, and converters, which oxidize copper matte to produce blister copper with a copper content of about 99%. In flash furnaces and converters, the raw materials are kept in a molten state by the heat of the oxidation reaction, and are separated into two phases, copper matte and slag, or blister copper and slag, which are then recovered. A solvent is added to the slag to obtain an appropriate composition and to lower the melting point during melting.

[0029] There are various types of fluxes for copper smelting, but silica ore, which is mainly composed of SiO2, is commonly used. When silica ore is used as a flux, the following reaction occurs in the flash furnace or converter. Flash furnace: CuFeS2+SiO2+O2→Cu2S·FeS+2FeO·SiO2+SO2 Converter:Cu2S·FeS+SiO2+O2→Cu+2FeO·SiO2+SO2

[0030] There are various types of glass fibers contained in synthetic wood, but glass fibers mainly composed of silicon oxides are common. Silicon oxides refer to inorganic oxides that contain silicon. Therefore, the incineration residue of synthetic wood can be used as a SiO2 source for the slag solvent in recycling furnaces and copper smelting furnaces. In addition, by supplying the incineration residue of synthetic wood to flash smelting furnaces, which have a large amount of copper concentrate processed and require a larger SiO2 source, a larger amount of processing can be expected.

[0031] However, since the glass fibers contained in synthetic wood may contain Al in the form of alumina, they also contain components that are unnecessary as a SiO2 source for slag. Therefore, it is preferable to mix the synthetic wood incineration residue with other SiO2 sources before supplying it to a recycling furnace or a non-ferrous smelting furnace. By thoroughly mixing the synthetic wood incineration residue with other SiO2 sources, it is possible to avoid sudden fluctuations in the components and form a stable slag. However, if the volume of the synthetic wood incineration residue is small and the effect on the components of the solvent in the recycling furnace or non-ferrous smelting furnace is small, it is also possible to supply the incineration residue as it is.

[0032] In addition, when silica ore is used as a SiO2 source for a non-ferrous smelting furnace such as a flash furnace, it is common to crush the silica ore with a crushing device before feeding it into the non-ferrous smelting furnace, but it is also preferable to crush the synthetic wood incineration residue before feeding it. This makes it possible to further homogenize the components.

[0033] Another embodiment of the synthetic wood recycling method of the present invention includes using at least a part of the incineration residue obtained by any of the embodiments of the synthetic wood incineration method of the present invention as a raw material for cement.

[0034] The raw materials for cement include limestone raw materials, which are mainly composed of calcium carbonate, clay raw materials, which are mainly composed of silicon dioxide and aluminum oxide (alumina), silica raw materials, which are mainly composed of silicon dioxide, and iron oxide raw materials. Impurities that may be contained in the raw materials for cement include chlorine, chromium, and other heavy metals (copper, lead, etc.), and it is preferable for these impurities to be low. The raw materials for cement are generally fired at a maximum of 1450°C in a firing furnace such as a kiln to become clinker, which is then cooled, crushed, and other finishing processes to become cement.

[0035] On the other hand, as described below, the incineration residue of synthetic wood is rich in calcium, silicon, and aluminum, but the amount of the above impurity elements is small or almost absent. Therefore, if the incineration residue is mixed with other conventional cement raw materials and then fired, it is possible to obtain clinker of a specified composition. Therefore, the incineration residue of synthetic wood can be suitably used as a raw material for cement. EXAMPLES

[0036] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0037] Example 1 A synthetic sleeper with dimensions of 2,600 mm in length, 200 mm in width, and 200 mm in thickness was prepared. The composition of the synthetic sleeper was glass fiber reinforced urethane foam with 50% by mass of alumina borosilicate glass (E glass) and 50% by mass of polymethylene polyphenyl polyisocyanate-polyol compound.

[0038] The synthetic sleeper was cut in the center of its length to make a piece of 1,300 mm length, and the volume was 25.8 m 3 The waste was placed in a fixed bed furnace and incinerated for 4 hours. The temperature inside the furnace during incineration was controlled within the range of 850℃ to 900℃. After incineration, it was confirmed that part of the incineration residue had turned into glass fiber bundles.

[0039] The same synthetic sleepers were also prepared and the above procedure was repeated for testing. Since the pieces of synthetic sleepers were long, the incineration residue was also long. After each test, 100g samples (samples 1 and 2 for the first test, samples 3 and 4 for the second test) were taken from near the center of the length of the incineration residue, near the center of the thickness direction, and near the surface, and the elemental composition was identified by inductively coupled plasma atomic emission spectrometry (ICP-AES). In addition, the two samples were combined into one sample and the ignition loss was measured using the above-mentioned method, and the measured value was used as the ignition loss of the entire incineration residue obtained by each test. The results are shown in Table 1.

[0040] [Table 1]

[0041] As can be seen from Table 1, by incinerating synthetic sleepers under specified conditions, it was possible to obtain an ignition loss of less than 10%. Furthermore, the amount of Si element in the incineration residue was approximately 60 mass% in oxide conversion, which indicated that it could be used as a slag solvent. In addition to Si, the amount of Al element was approximately 14 mass% in oxide conversion, and the amount of Ca element was also approximately 23 mass% in oxide conversion. The total amount of these three elements in oxide conversion was close to 100 mass%, and the amount of Cr, which is considered an impurity, was very small, which indicated that it could be used suitably as a raw material for cement.

[0042] Example 2 The change in the overall ignition loss was investigated when the thickness of a synthetic sleeper was halved. Specifically, a synthetic sleeper with dimensions of 2,600 mm length x 120 mm width x 150 mm thickness was prepared. The composition of the synthetic sleeper was glass fiber reinforced urethane foam with 50 mass% alumina borosilicate glass (E glass) and 50 mass% polymethylene polyphenyl polyisocyanate polyol compound.

[0043] The synthetic sleeper was cut into small pieces 250 mm long, and one of the pieces was placed in a container with a volume of 25.8 m 3The piece was placed in a fixed-bed furnace and incinerated for 3 hours. The temperature inside the furnace during incineration was controlled within the range of 800°C to 850°C. Next, the other piece was cut in half in the thickness direction to make two pieces measuring 250 mm in length, 120 mm in width, and 75 mm in thickness, and these two pieces were placed in the same place in the same incinerator and incinerated under the same conditions. After incineration, it was confirmed that part of the incineration residue had become glass fiber bundles.

[0044] After the two tests, samples were taken and the ignition loss was measured in the same manner as in Example 1. In order to compare the efficiency of incineration, the total weight of the sleeper pieces before incineration and the total weight of the incineration residue after incineration were also measured. The results are shown in Table 2.

[0045] [Table 2]

[0046] As can be seen from Table 2, cutting the synthetic sleepers into smaller pieces prior to incineration improved the efficiency of incineration and resulted in better (lower) ignition loss.

[0047] Example 3 The change in ignition loss was investigated when pieces of synthetic sleepers were incinerated while stacked in a tower shape. Specifically, synthetic sleepers with dimensions of 2,600 mm length x 150 mm width x 150 mm thickness were prepared. The composition of the synthetic sleepers was glass fiber reinforced urethane foam with 50 mass% alumina borosilicate glass (E glass) and 50 mass% polymethylene polyphenyl polyisocyanate polyol compound.

[0048] A piece of 1,200 mm in length was cut from a synthetic sleeper, and multiple pieces with dimensions of 1,200 mm in length × 150 mm in width × 150 mm in thickness were prepared. As shown in Figure 1, four pieces were arranged at intervals to form one layer, and up to six layers were stacked. When these were stored in a mesh metal cage, the volume was 25.8 m 3 The samples were placed in a fixed bed furnace and incinerated for 4 hours. The temperature inside the furnace during incineration was controlled within the range of 850℃ to 900℃.

[0049] After incineration, the incineration residue was piled up in a shape similar to the original sleeper pieces, but when some of the incineration residue was removed, it was confirmed that part of the incineration residue had become glass fiber bundles (Fig. 2). 50g samples were taken from near the center of the incineration residue in the length direction, near the center in the thickness direction, near the surface, and near the middle between the center and the surface, and the ignition loss was measured using the method described above. In order to evaluate the efficiency of incineration, the total weight of the sleeper pieces before incineration and the total weight of the incineration residue after incineration were also measured. The results are shown in Table 3.

[0050] [Table 3]

[0051] As can be seen from Table 3, even when the pieces of synthetic sleepers were incinerated in a tower-like configuration, they could be incinerated with high efficiency, resulting in an ignition loss of less than 10%.

Claims

1. A method for incinerating synthetic wood having a maximum dimension exceeding 1.5 m, the method comprising the steps of: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; a second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing glass fiber material; The incineration method according to claim 1, wherein the synthetic wood is a synthetic sleeper, and the ignition loss of the incineration residue is less than 10%.

2. 2. The incineration method according to claim 1, wherein the second step melts and solidifies at least a portion of the glass fiber material to form an integrated glass fiber bundle.

3. The incineration method according to claim 1 or 2, wherein the incineration residue contains 40 mass% or more of silicon dioxide in terms of oxide.

4. 2. The incineration method according to claim 1, wherein in the second step, the cut pieces are incinerated in a state in which the cut pieces are stacked in a tower shape and placed in an incinerator.

5. The incineration method according to claim 1 or 4, wherein the synthetic sleepers have a length of 2.5 m to 5.0 m, a width of 0.1 m to 0.4 m, and a thickness of 0.1 m to 0.4 m.

6. A method for recycling synthetic wood having a maximum dimension exceeding 1.5 m, which is made of fiber-reinforced plastic containing glass fiber material, comprising: The method comprises: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; A second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing a glass fiber material; At least a portion of the incineration residue is used as a solvent for slag; The incineration residue contains 40 mass % or more of silicon dioxide calculated as an oxide.

7. A method for recycling synthetic wood having a maximum dimension exceeding 1.5 m, which is made of fiber-reinforced plastic containing glass fiber material, comprising: The method comprises: A first step of cutting the synthetic wood into pieces with a maximum dimension of 1.5 m or less; A second step of incinerating the slices at a temperature of 600° C. to 1200° C. for 2 hours to 6 hours to obtain an incineration residue containing a glass fiber material; At least a part of the incineration residue is used as a raw material for cement, The recycling method according to claim 1, wherein the incineration residue contains 40 mass % or more of silicon dioxide calculated as an oxide.

8. 8. The recycling method according to claim 6 or 7, wherein in the second step, at least a part of the glass fiber material is melted and solidified to form an integrated glass fiber bundle.

9. The recycling method according to any one of claims 6 to 8, wherein the synthetic wood is a synthetic sleeper.

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