Method and apparatus for removing dye from textile waste

Abstract

To recover a dye from textile waste by a safe, easy and environmentally clean means.SOLUTION: A batch of textile waste is reduced in size to clippings, extracted with a solvent under agitation, centrifuged to remove the solvent, and the solution comprising the solvent and extracted material is used as the solvent for extraction of another batch.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and plant for removing dyes from textile waste in order to recycle textile materials such as fabrics, yarns, filaments, and garments. More particularly, the present invention relates to a method for recovering polyester material, together with cellulosic material, from dyed fabric and garment waste. [Background technology]

[0002] Recycling of pre-consumer, post-industrial, post-consumer, used fabrics and garments (also known as "textile scrap" or "fabric scrap") has become a primary goal in the textile industry: new and efficient recycling methods are being actively investigated. One goal is to provide methods for recycling materials present in widely used fabrics and textiles.

[0003] The challenges of using post-consumer textiles in these processes include residues of contaminants that cause chemical reactions that reduce the molecular weight of the polyester and other materials that weaken the fiber. The challenge in recycling polyester- or cotton-containing fabrics essentially lies in removing contaminants such as dyes and polyurethane materials (e.g., elastin filaments) from the polyester or cotton fibers and filaments of the fabric.

[0004] WO2022 / 118244 discloses the recycling of waste polyester materials (including textile scraps) by dissolving the polyester in a solution comprising hexafluoroisopropyl alcohol and chlorinated hydrocarbons and / or aromatic hydrocarbons. Prior to dissolution, a pretreatment using dichloromethane (DCM) is carried out to remove colorants and impurities from the PET bottles and textile scraps. This method does not provide efficient and complete removal of dyes.

[0005] US2022169786 discloses a method for producing decolorized polyester by removing colorant from polyester with a decolorizing agent containing a glycol ether type compound having a boiling point of 160°C or higher at atmospheric pressure while heating the decolorizing agent to a temperature at or below the melting point of the polyester.

[0006] EP3699355 discloses a method and system for decolorizing textile waste dyed with disperse dyes using a magnetically charged dye-absorbing material in a hydrothermal environment. The textile material is treated under agitation in a decolorizing reactor containing water and magnetically activated carbon as the dye-absorbing material, under autogenous pressure, such as that obtained when heated to approximately 100-170°C. An ultrasonic generator is used to promote the release of dye molecules from the textile into the water. The dye released from the polyester fibers is adsorbed by the magnetically charged carbon (which is collected at the end of the process by activating a magnetic field).

[0007] US 4,003,881 relates to a method for recovering polyester polymer by stripping dye from dyed polyester fibers, followed by dissolving the polyester fibers and then precipitating the polyester polymer for reuse. Summary of the Invention [Problem to be solved by the invention]

[0008] Generally, known methods result in partial degradation of the polyester polymer material and / or cotton fibers and often only partial removal of the dye; in particular, Applicant has recognized that operation under mild conditions is necessary to reduce degradation of the polyester and / or cotton. Degradation of the polyester is detrimental to the reusability of the recovered polyester material. Similarly, degradation of the cotton fibers compromises the mechanical properties and appearance of yarns made from recycled cotton fibers.

[0009] In particular, it would be extremely useful to have a method that can remove all dyes (e.g., disperse and vat dyes) and decorations from dyed or printed / decorated textile materials in a short time without degrading or damaging the polyester and / or cotton fibers contained in the textile.

[0010] A further challenge is that polyester-based fabrics and garments often contain polyurethane materials (either as elastane-type filaments in fabric yarns or as printed layers on garments as decoration, for example in sports apparel). The presence of elastomeric materials is problematic when polyester and / or cotton fibers are recycled. [Means for solving the problem]

[0011] The object of the present invention is to solve the above problems and to provide a method for recycling textile waste comprising polyester and / or cellulose fibers, in particular a method for recovering dyes from waste comprising polyester and / or cellulose fibers, which method provides a safe, easy, and environmentally clean means of recovering polyester and / or cellulose materials from textile waste. Another object of the present invention is to provide a method for removing dyes from textile waste comprising polyester and / or cellulose fibers, which method reduces or does not cause degradation of the polyester and / or cellulose materials. A particular object of the present invention is to provide a method for recovering dyes from textile waste in an environmentally friendly (i.e., "clean") manner, i.e., a closed-loop method carried out in a fully closed-loop plant (apparatus), whereby the solvents used (including water) are fully recovered and reused in the process.

[0012] The decolorized material is then recycled by methods known per se in the art. For example, the decolorized polyester material can be further recycled by depolymerizing the polyester or by recovering the polyester as staple fibers. Another preferred recycling method is to convert the decolorized PET and polyester material into PET chips or beads for use in fiber spinning or molding processes, depending on the intended application. Cellulose fibers that may be present in the textile waste can be removed from the polyester filaments or fibers, for example, by chemical or enzymatic degradation of the cellulose fibers.

[0013] Similarly, decolorized cotton or cellulosic material can be recycled in a manner known per se, for example by mechanically providing cellulose staple fibers (including regenerated cellulose fibers, e.g., cotton fibers or regenerated cotton fibers) (the staple fibers being processed into yarns).

[0014] In the case of pre-consumer materials, particularly those present in clothing or fabrics, the clothing or fabrics are recycled by bleaching them to a raw (undyed) state and subsequently dyeing or printing or both of the treated clothing.

[0015] The problem is solved by a method according to claims 1 and 2 and by an apparatus, i.e. a plant, according to claim 18. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention comprising one extraction chamber and one centrifuge. [Figure 2] FIG. 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention comprising two extraction chambers and two centrifuges. [Figure 3] FIG. 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention comprising four extraction chambers and four centrifuges. [Figure 4]1 is a schematic diagram of an embodiment of the method and apparatus of the present invention including a mechanical treatment and quality control unit for the textile before extraction. [Figure 5] 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention including a textile washing unit after the quality control unit. [Figure 6] Photographs showing the appearance of a textile material (a small piece of polyester fabric) at each step of the process. DETAILED DESCRIPTION OF THE INVENTION

[0017] The object of the present invention is a method for removing dyes from textile materials, in particular textile waste, comprising dyes and at least 70% by weight of polyester fibers or dyes and at least 90% by weight of cellulose fibers, said method comprising the following steps: a) providing a textile material and a solvent suitable for removing dye from the textile in an extraction chamber to provide a textile and solvent mixture; b) extracting the textile with said solvent to provide a solution comprising the solvent and extracted substances, wherein the extracted substances include at least the dye, and wherein the textile material and the solvent are agitated in an extraction chamber during at least a portion of the extraction step, preferably during the entire extraction step; c) removing the solution comprising the solvent and the extracted substances from the fabric. comprising the steps of: a1) reducing the textile material to pieces preferably having a maximum dimension of 5 cm before feeding it into the extraction chamber; b1) after step b), feeding the mixture of solvent and fabric pieces into a centrifuge to carry out step c); c1) After step c), a solvent heated to a temperature suitable for removing the dye, preferably between 80 and 140°C, is fed into the centrifuge to wash the fabric and remove any residual dye from the fabric. wherein the bath ratio of fabric (kg):solvent (L) is within the range of 1:3 to 1:20 (kg / L).

[0018] Another object of the present invention is a method for removing dyes from textile materials, in particular textile waste, the textile materials comprising at least 50%, preferably at least 60%, more preferably at least 70% by weight of polyester fibres, said method comprising the following steps: a) providing a batch of textile material to an extraction chamber; b) extracting the batch of textile with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the textile material and the solvent are agitated in the extraction chamber during at least a portion of the extraction step, preferably during the entire extraction step; c) removing the solution comprising the solvent and extracted substances from the fabric. wherein the solution comprising the solvent and the extracted substances obtained in step b) and / or step c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are preferably repeated until the amount of extracted substances in the solution comprising the solvent and the extracted substances reaches a concentration at which further extraction of dye is impaired.

[0019] Furthermore, the object of the present invention is a method for removing dyes from textile materials, in particular textile waste, the textile materials comprising at least 80% by weight, preferably at least 90% by weight, of cellulose fibers, preferably cotton fibers, wherein at least a portion of the cellulose fibers are preferably dyed with indigo, said method comprising the following steps: a) providing a batch of textile material to an extraction chamber; b) extracting the batch of textile with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the textile material and the solvent are agitated in the extraction chamber during at least a portion of the extraction step, preferably during the entire extraction step; c) removing the solution comprising the solvent and extracted substances from the fabric. wherein the solution comprising the solvent and the extracted substances obtained in step b) and / or step c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are preferably repeated until the amount of extracted substances in the solution comprising the solvent and the extracted substances reaches a concentration at which further dye extraction is impaired.

[0020] Advantageously, it has been observed that the method of the present invention allows for the recycling of textile waste comprising polyester and / or cellulose fibers, particularly the removal of dyes from textile waste comprising polyester and / or cellulose fibers, to be carried out in a safe, rapid, easy, and environmentally friendly manner. The method of the present invention also allows for the removal of dyes from textile waste comprising polyester and / or cellulose fibers with reduced or no degradation of the polyester and / or cellulose materials in the textile waste. The method of the present invention allows for the effective removal of dyes from textiles containing both polyester and cotton. Advantageously, even when the textile waste also contains polyurethane materials, such as elastane or polyurethane prints or coatings, the polyurethane materials are effectively removed. The method of the present invention allows for the effective isolation and recovery of polyester materials (particularly polyester fibers and filaments) along with cellulose materials from textile waste, for example, textile waste containing multiple different dyes. Furthermore, it allows for the recovery of substantially all of the solvent used. In particular, the method of the present invention allows for solvent recovery rates of at least 99% and even 99.9% or more.

[0021] As used herein, the term "extracted material" refers to material, including dyes and other components and contaminants, that have been removed from textile waste by treating the textile waste in accordance with this specification, i.e., by extracting the textile waste with a solvent.

[0022] According to an embodiment, the extraction chamber (or extractor) is a device known per se in the art. For example, the extraction chamber (extractor) is selected from a single / double shaft mixer, a wash screw, a washer-like reactor, and a solvent washer. In an embodiment, the extraction chamber is a cylindrical vessel, such as a drum, with a rotation axis arranged substantially horizontally. In another embodiment, the extraction chamber is a stationary vessel containing an impeller that rotates around the rotation axis within the extraction chamber. The extraction chamber can have a vertical or horizontal rotation axis. Preferably, the extraction chamber is equipped with insulation to help maintain the solvent at the temperature required for best dye removal.

[0023] Preferred solvents are DMF (dimethylformamide) or DMAC (dimethylacetamide) or a mixture of DMF or DMAC with alkaline water, or mixtures thereof. Preferably, the solvent is DMF. In an embodiment for bleaching textiles containing or consisting of dyed cotton fibers, the solvent comprises DMF and alkaline water, preferably a reducing agent for the dye. As used herein, the term "alkaline water" refers to water having a pH of at least 10, e.g., in the range of 10 to 13.5. The pH is adjusted by adding a base, e.g., NaOH and KOH, to the water.

[0024] The solvent is heated to a temperature suitable for removing the dye from the fabric.

[0025] According to a specific embodiment, the extraction chamber containing the solvent is rotated about its horizontal axis, thereby agitating the textile material in the extraction chamber for at least part of the extraction step (i.e., step b), preferably for the entire extraction step. In a specific embodiment, the textile material is agitated in the extraction chamber by at least one impeller (the impeller is arranged along the horizontal or vertical axis of the extraction chamber, which is preferably stationary). Preferably, the extraction chamber is thermally insulated.

[0026] The expressions "agitate," "agitated," and "agitation" define the movement of the fabric pieces together with the solvent, as obtained by i) rotation of the extraction chamber or extraction vessel around its axis of rotation, or ii) rotation of an impeller or similar device suitable for imparting movement to a mixture of solvent and fabric pieces in a stationary vessel. The two movements may also be combined. As mentioned above, in one embodiment, the extraction chamber is a cylindrical vessel with a substantially horizontally oriented axis of rotation; preferably, the extraction chamber is housed in a tank. In another embodiment, the extraction chamber is a stationary vessel housing an impeller that rotates around the vertical axis of the extraction chamber or along a horizontal axis.

[0027] According to a specific embodiment, step c) comprises separating the solution comprising the solvent and the extracted substances from the textile material by centrifugation. Advantageously, after the extraction step is completed, the use of centrifugation (especially applied to textile materials impregnated with the solution comprising the solvent and the extracted substances) allows for effective separation of the textile material from the solution comprising the solvent and the extracted substances (which were captured by the textile material), thus achieving particularly effective removal of the dye and residual solvent from the textile material. This further results in less energy consumption for drying the textile material recovered at the end of the method, since most of the solvent and / or the solution comprising the solvent and the extracted substances has already been removed. In addition, the use of centrifugal force also allows for a reduction in the number of extractions (step b)) required to remove the dye (and optionally other substances) from the textile material. Centrifugation is also a particularly safe technique for removing all the solvent from the textile. According to a specific embodiment, the centrifuge is a centrifuge that rotates around its horizontal axis; in other embodiments, the centrifuge rotates around its vertical axis.

[0028] According to a specific example, extraction step b) has a duration of 2 to 20 minutes, preferably 5 to 15 minutes, more preferably 7.5 to 12.5 minutes, and most preferably 10 minutes. As discussed below, the centrifugation step of the method is preferably carried out for 1 to 5 minutes; this results in a total process time of about 25 to 35 minutes to complete the removal of the dye from the textile pieces. The short time required by the present invention is a surprising result when compared to the time required by prior art methods, such as those in US 4,003,881, which can take up to 270 minutes or require several extraction steps.

[0029] According to a specific example, the temperature of the solvent (or the solution comprising the solvent and the extracted substance) in the extraction chamber is in the range of 80 to 140°C, preferably 82 to 135°C. The temperature is selected depending on the solvent used and the dye to be removed. For example, when DMF is used as the solvent, the temperature of the solvent (or the solution comprising the solvent and the extracted substance) in the extraction chamber is about 90°C.

[0030] Advantageously, the solvent in contact with the mixture of solvent and textile material, i.e., textile pieces, is maintained at a temperature in accordance with the above disclosure. For this purpose, parts of the apparatus for containing the textile and solvent are preferably thermally insulated; in particular, at least the ducts supplying the solvent / textile mixture to the extraction chamber and the centrifuge are thermally insulated. In a preferred embodiment of the plant, all ducts, pipes, tanks, and reservoirs for containing the solvent are thermally insulated by means known per se in the art. In addition, the apparatus provides a closed system with zero emissions. In fact, the solvent used in the process is recovered at 99.9% after distillation, so that the process is a completely closed-loop process in the apparatus of the present invention.

[0031] According to a specific example, step b) is repeated at least twice, and preferably, between each repetition, recovery of the solution comprising the solvent and the extracted substances is performed according to step c), preferably by centrifugation. In a specific example, centrifugation is performed in an extraction chamber. For example, if the extraction chamber is a washer or solvent purifier, the extraction chamber can perform centrifugation and drying. Preferably, the extraction chamber is different from the centrifugal separator (i.e., a centrifuge). According to a specific example, centrifugation is performed at a G force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1200, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. For example, centrifugation is performed at a G force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300. In a specific example, after each centrifugation, the solution of the solvent and the extracted substances is reused to process another batch of textile material.

[0032] According to an embodiment, a portion of the solution comprising the solvent and extracted substances obtained during step b) is removed from the extraction chamber before step c), in other words, in an embodiment, the solution comprising the solvent and extracted substances obtained during step b) is removed from the extraction chamber.

[0033] According to a specific embodiment, step c) is carried out in a centrifuge. For example, the centrifuge is selected from a vertical peeler-type bottom discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, and a decanter-type centrifuge. Preferably, the centrifuge comprises a filtering means for filtering fiber particles from the solvent exiting the centrifuge. In a specific embodiment, the centrifuge rotates about its horizontal axis. In a specific embodiment, both the extraction chamber and the centrifuge rotate about their horizontal axes. In a specific embodiment, the extraction chamber comprises a paddle-type impeller that rotates about the horizontal axis of the extraction chamber and includes paddles arranged along the impeller shaft, so that the mixture of solvent and textile material is moved along the horizontal axis from the inlet of the extraction chamber to the outlet on the opposite side of the extraction chamber during the extraction process.

[0034] In a specific example, after centrifugation, the textile pieces after solvent removal in the centrifuge are subjected to a washing step. Preferably, the washing step is carried out in a centrifuge. In this case, the centrifuged textile material is washed using fresh solvent supplied to the interior of the centrifuge via a solvent supply line; during the washing step, the centrifuge is rotated at a reduced speed relative to the centrifugal speed, i.e., a speed effective for washing the textile pieces, preferably in the range of 300 to 700 rpm, more preferably 400 to 600 rpm. According to a specific example, hot washing is carried out, e.g., the temperature of the solvent supplied to the centrifuge for the washing step is high enough to quickly raise the temperature of the mixture of textile pieces and solvent to a temperature equal to or higher than the temperature of the solvent used for extraction of the textile material. The washing step is carried out for a time period ranging from 3 to 10 minutes, and more preferably, about 5 to 6 minutes is sufficient to remove residual dye. After washing, the textile is centrifuged again to remove the solvent remaining on the textile used in the washing step. The final solvent content of the fabric pieces after centrifugation is generally 4-7% by weight; this has the advantage that a "ring cake" is formed at the end of the centrifugation process, i.e., a layer of small fabric pieces that adhere to the side walls of the centrifuge. Such cake is easily removed from the wall by process means, such as a scraper mounted on the centrifuge door or a screw that feeds the scraped fabric particles to the outside of the centrifuge.

[0035] After centrifugation and optional washing, the textile is dried. For example, the centrifuged textile is transferred from the centrifuge to a drying device and dried. Advantageously, the solvent is also recovered, restored, and collected during the drying process. According to a specific example, after centrifugation and optional washing, but before drying, the textile, typically a sample of the treated textile, is checked in a quality control unit, where the amount of dye in the textile is measured according to techniques known per se in the art, for example, color measurement using a spectrophotometer, i.e., Datacolor. If the dye is still present in the textile in an unacceptable amount, the textile material is returned to the extraction chamber and extracted again according to step b) of the method of the present invention. If the dye has been sufficiently removed from the textile, the textile is dried. According to a specific example, before being sent to the drying step, the textile is subjected to a water wash to remove the original solvent, i.e., DMF or DMAC.

[0036] According to a specific example, preferably before being transferred to the centrifuge, the textile material obtained in step b) is transferred from the extraction chamber to a storage tank, for example, when the centrifuge cannot hold the entire amount of textile material processed in the extraction chamber and therefore another batch of textile material is extracted in the extraction chamber while centrifuging the textile material obtained in step b).

[0037] According to a specific example, if the amount of extracted substances in the solution comprising the solvent and extracted substances is at a concentration that would impair further dye extraction, the solution comprising the solvent and extracted substances is fed to a distillation apparatus to separate the solvent from the extracted substances. In this case, the solvent is advantageously recovered and reused. Also, the extracted substances, e.g., dyes, elastane and / or other polyurethane materials, are recovered and further processed. For example, if all the textiles to be processed are dyed with the same dye (disperse or vat dye), the dye is also recovered and reused without further treatment or processing.

[0038] According to a specific example, the distillation, in particular the distillation of DMF, is carried out at a temperature ranging from 70 to 100°C, preferably from 75 to 95°C, more preferably from 80 to 90°C, and at a pressure ranging from 15 to 90 mbar, preferably from 20 to 85 mbar, more preferably from 40 to 80 mbar.

[0039] According to an embodiment, the textile material is provided to the extraction chamber in a form selected from fabric powder, fibers, filaments, yarns, fabric, fabric clippings (e.g., pieces), garments, garment clippings (e.g., pieces), and mixtures thereof. The powdered textile material can be obtained by grinding other forms of textile waste, such as fabric or garments. According to an embodiment, the method of the present invention further comprises the step of grinding the textile waste to obtain a powder, preferably a polyester powder.

[0040] According to an embodiment, the method of the present invention comprises the step of mechanically treating textiles, preferably cloth and garments, to reduce their dimensions to obtain pieces of textiles, preferably cloth and garment pieces (e.g. cloth and garment clippings). In a preferred embodiment, the material is fed to the extraction chamber after mechanical treatment in the form of cloth or garment pieces (i.e. clippings) (at least 90% of the pieces have a dimension between 1 and 50 mm).

[0041] According to a specific embodiment, the material is a polyester-based fabric, optionally with elastane filaments, and is fed to the extraction chamber in the form of small pieces of fabric or clothing (i.e., clippings), where at least 90% of the fabric or clothing pieces have a dimension of 2-2.5 mm. Fabric and / or clothing pieces with the above dimensions are obtained by techniques and means known per se in the art, for example, by crushing devices or shredders. According to another specific embodiment, when the textile waste contains cotton fibers to be recycled, preferably containing at least 50% cotton fibers, the fabric is fed to the extraction chamber in the form of fabric pieces (i.e., clippings), where 90% of the fabric pieces have a dimension of at least 20 mm, preferably in the range of 20-50 mm.

[0042] The advantage of using textile waste, i.e., woven or knitted fabric in the form of reduced-size pieces as described above, is that extraction times are dramatically reduced; for example, in accordance with the present invention, the extraction of 400 kg of woven polyester pieces with hot (90-95°C) DMF under stirring in an extraction chamber takes only 10 minutes. Also, the subsequent centrifugation and washing step with hot DMF solvent in a centrifuge at reduced rpm is completed in 5-10 minutes. Another advantage is that the mixture of fabric pieces and hot solvent is transported along pipes from one part of the equipment, i.e., plant, to another.

[0043] According to a specific example, the textile material, optionally after a mechanical treatment step for size reduction, is mixed with a solvent in a ratio of textile pieces (kg) to solvent (L) ranging from 1:8 to 1:20, preferably from 1:10 to 1:20, such that the mixture (preferably having a slurry-like consistency) is suitable for being fed from the extraction chamber along the device to a centrifuge, for example by pumping or an Archimedes screw.

[0044] According to an embodiment, the textile material comprises a plurality of dyes. According to an embodiment, the polyester fibers in the textile material comprise at least a dye selected from a disperse dye and a vat dye, and / or the polyester fibers are dope-dyed. According to an embodiment, the cellulose fibers, preferably cotton fibers, in the textile material can comprise at least one dye selected from a vat dye, a reactive dye, a direct dye, a sulfur dye, and mixtures thereof. According to an embodiment, the cellulose fibers, preferably cotton fibers, in the textile material can comprise at least one vat dye, preferably indigo.

[0045] For example, fabrics recycled by the method of the present invention include polyester sports apparel (e.g., T-shirts) and garments that have decorations printed onto a thin layer or film of polyurethane material that is applied to the garment. The polyurethane layer is dissolved by a solvent, along with the ink that forms the decorative elements (e.g., logos or numbers, etc.).

[0046] As used herein, reference is made to "polyurethane materials" or PU materials; this term encompasses elastomeric materials used in yarns (e.g., elastane and spandex) and any other polyurethane materials that may be present on or in fabrics, for example, as decorations (e.g., printed decorations) or coatings.

[0047] According to an embodiment, at least a portion of the polyester fibers are dyed, preferably with at least one disperse dye, or dope dyed. According to an embodiment, all of the polyester fibers in the textile material are dyed, preferably with at least one disperse dye, optionally with a plurality of disperse dyes, or dope dyed.

[0048] According to a specific embodiment, step b) is carried out one or more times, preferably each time in a different extraction chamber, and / or step c) is carried out one or more times, optionally each time in a different centrifuge. The extraction chambers are arranged in series. In one embodiment, each extraction chamber comprises a centrifuge.

[0049] According to a specific embodiment, the extraction chamber is a first extraction chamber, and after the first extraction step b), the textile material is fed from the first extraction chamber to a first centrifuge for a first removal step c). Thereafter, the textile material is fed from the first centrifuge to a second extraction chamber for a second extraction step b) and then from the second extraction chamber to a second centrifuge for a second removal step c). In a specific embodiment, the first and second extraction steps b) and the first and second removal steps c) are carried out in two different extraction chambers and two different centrifuges, respectively.

[0050] According to a specific example, several batches of textile waste are extracted with the same solvent batch. For example, after extraction in the second extraction chamber, once the dye has been completely removed, the solvent used in the second extraction chamber and / or the second centrifuge is preferably supplied from the second extraction chamber to the first extraction chamber to extract the next batch of textile material. In this case, advantageously, the solvent (i.e., the solution comprising the solvent and the extracted substances) removed from the second extraction chamber and / or the second centrifuge is used to further increase the concentration of the extracted substances in the solution for extracting the next batch of textile material, thus reducing the amount of solvent required for the process. For example, the textile waste is extracted with the solvent in the first extraction chamber, centrifuged, then extracted again in the second extraction chamber, followed by centrifuging again, preferably in a second centrifuge. Fresh solvent may be used for the second extraction step.

[0051] After the second extraction step, a solution comprising the solvent and extracted substances is obtained; the solution (including the residual solution recovered from the second centrifuge after centrifuging the textile material after the second extraction) is reused in the second extraction chamber for multiple extractions, for example, up to 20, preferably up to 30, and more preferably up to 40 extractions. At this point, the solution comprising the solvent and extracted substances is fed to the first extraction chamber and reused for extracting textile waste until the extracted substances in the solution reach a concentration that impairs further dye extraction. When the extracted substances in the solution reach a concentration that impairs further dye extraction, the solution comprising the solvent and extracted substances is fed to a distillation device, thereby distilling and recovering the solvent. In other words, when further dye extraction in the first extraction chamber is impaired, the solution comprising the solvent and extracted substances is fed to a distillation device, and the solution comprising the solvent and extracted substances obtained in the second extraction chamber is fed to the first extraction chamber. In this case, advantageously, the concentration of the extracted substances in the solution comprising the solvent and the extracted substances obtained in the second extraction chamber is not limiting, as long as the solution comprising the solvent and the extracted substances obtained in the second extraction chamber is suitable for carrying out extraction step b) on further batches of textile in the first extraction chamber.

[0052] According to a specific example, steps b) and c) are repeated two or more times in two or more extraction chambers and centrifuges, with the solvent recovered from any extraction chamber different from the first chamber being fed to the previous extraction chamber. In this case, advantageously, the solvent (i.e., the solution comprising the solvent and the extracted substances) recovered from any second or further extraction chamber is used to extract the next batch of textile material in the previous extraction chamber, so that the concentration of the extracted substances in the solution increases whenever the solution moves from one extraction chamber to the previous one, so that a new batch of textile material is extracted for the first time in the first extraction chamber with the solution comprising the solvent and the extracted substances, and then treated in the subsequent extraction chambers using solutions having progressively decreasing concentrations of the extracted substances.

[0053] According to a specific embodiment, the solvent (i.e., the solution comprising the solvent and extracted substances) exiting the extraction chamber is filtered to maximize the amount of fabric debris remaining in the extraction chamber and to keep the solution comprising the solvent and extracted substances solids-free.

[0054] According to an embodiment, the solvent used in step b) contains already extracted substances (the extracted substances include at least dyes) before the start of step b). In other words, according to an embodiment, the solvent used in step b) is in the form of a solution comprising the solvent and the extracted substances (the extracted substances include at least dyes). In an embodiment, the solvent containing already extracted substances is supplied to the extraction chamber from a solvent storage tank. In an embodiment, such a solvent storage tank is configured to receive the solution comprising the solvent and extracted substances exiting the extraction chamber and / or the centrifuge. In an embodiment, the extracted substances in the solution may originate from other processes and / or plants. In an embodiment, the extracted substances in the solution may originate from a batch of textile material that has already been treated according to the method of the present invention.

[0055] According to a specific example, the solvent is DMF (dimethylformamide) or DMAC (dimethylacetamide) or a mixture of DMF or DMAC with alkaline water, or a mixture thereof. Preferably, the solvent is DMF. In an example where the textile comprises cotton fibers and a suitable dye, the solvent comprises DMF and alkaline water. As used herein, the term "alkaline water" refers to water having a pH of at least 10, e.g., in the range of 10 to 13.5. The pH is adjusted by adding a base, e.g., NaOH and KOH, to the water.

[0056] According to a specific example, the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 3.5 to 1 / 10, more preferably 1 / 4 to 1 / 6 (kg / L). In a specific example, the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 10 to 1 / 20. The advantage of a liquor ratio of 1 / 10 to 1 / 20 is that the mixture of fabric pieces and solvent is suitable for pumping along duct means, for example, from the mixing tank to the extraction chamber and from the extraction chamber to the centrifuge. In a specific example, additional solvent and / or additional solutions comprising the solvent and the extracted substances are added to maintain the liquor ratio within the above-mentioned range.

[0057] According to a specific example, step c) is carried out in a centrifuge at a G-force in the range of 250-5000, preferably 800-2000, more preferably 900-1300, for a time in the range of 0.5-10 minutes, preferably 1-5 minutes. The force exerted on the sample in the centrifuge is a function of the rotation speed (RPM) of the centrifuge and the radius of the rotor. Knowing the radius of the rotor (cm), the formula for calculating the G-force (gravitational equivalent) is: G-force = 0.00001118 x rotor radius x (RPM) 2 is.

[0058] In an embodiment, the textile waste may be pre-treated before being extracted according to step b), for example, the size of the textile waste is reduced, for example, by cutting the cloth or garment (e.g., 100% PET cloth or garment) into clippings, by cutting the clippings (e.g., 100% PET clippings) to further reduce their size, or by grinding the cloth or garment or clippings to obtain a powder, preferably a 100% PET powder.

[0059] According to a specific example, the waste is first processed to obtain pieces of fabric (e.g., clippings) having dimensions of 1 to 50 mm, preferably 2 to 10 mm, more preferably 2 to 2.5 mm, in particular for polyester fabrics. According to a specific example, when the textile material contains cotton (at least 50% cotton), the dimensions of the pieces are in the range of 20 to 50 mm.

[0060] In a specific example, if the textile material contains 50% by weight or less, preferably 30% by weight, of cotton, the textile material is pretreated to reduce the amount of cotton in the extracted textile material. For example, the amount of cotton in the textile material is reduced by pretreating the textile scraps with cellulase enzymes or chemical reactants suitable for depolymerizing cotton (or other cellulosic materials) (e.g., treatment with organic or inorganic acids), according to techniques known in the art. In a specific example, if the textile material contains elastane fibers, the textile material can be pretreated to reduce the amount of elastane in the extracted textile material. For example, the amount of elastane in the textile is reduced by pretreating the textile scraps with DMF, according to techniques known in the art. Advantageously, the method of the present invention is particularly effective when it comprises a step of pretreating the textile scraps.

[0061] According to an embodiment, the textile material is made of polyester fibers. In other words, according to an embodiment, the textile material is selected from polyester fibers, polyester filaments, polyester yarns, polyester fabric, clippings of polyester fabric (i.e., 100% polyester fabric), polyester garment, clippings of polyester garment, and mixtures thereof. For example, the textile material is selected from polyester fibers (i.e., 100% polyester fabric), clippings made of polyester fibers (100% polyester fabric or clippings from textile), polyester fibers, and mixtures thereof. According to an embodiment, at least a portion of the polyester fibers in the textile material made of polyester fibers are dyed. According to an embodiment, all of the polyester fibers in the textile material made of polyester fibers are dyed. According to an embodiment, the textile material made of polyester fibers contains a plurality of dyes, for example, a plurality of disperse dyes.

[0062] According to a specific example, the textile material is selected from fabrics made of polyester fibers, clippings made of polyester fibers (i.e. pieces of fabric and / or clothing, preferably having the above-mentioned dimensions) and mixtures thereof, at least some of the polyester fibers being dyed with at least one disperse dye. In this case, the solvent is preferably DMF, and the temperature of the solvent (or the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 85-105°C, preferably 95-100°C.

[0063] According to a specific example, the textile material is polyester fibers (i.e., separated fibers), and the polyester fibers are dyed with at least one disperse dye. In this case, the solvent is preferably DMF, and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in step b) in the extraction chamber is in the range of 80-110°C, preferably 85-105°C.

[0064] According to a specific example, the textile material is in the form of a clipping (i.e. a piece of fabric and / or clothing, preferably having the above-mentioned dimensions) made of polyester fibers, at least some of the polyester fibers being dope-dyed. In this case, the solvent is preferably DMF, and the temperature of the solvent (or the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 80 to 140°C, preferably 85 to 130°C.

[0065] According to a specific embodiment, the textile waste also comprises at least a polyurethane material, preferably elastane. According to a specific embodiment, the textile material comprises polyester fibers and further comprises at least one polyurethane material, preferably elastane. In this case, advantageously, the polyurethane material, e.g., elastane, contained in the textile material is extracted together with the dye. For example, the textile material can comprise at least 90% by weight of polyester fibers and further comprise one or more polyurethane materials, preferably elastane, more preferably at most 10% by weight of elastane. In a specific embodiment, the textile material comprises 90% by weight of polyester fibers and 10% by weight of elastane.

[0066] According to a specific example, the textile material comprises at least 90% by weight of polyester fibres and at most 10% by weight of elastane fibres, at least some of the polyester fibres being dyed with at least one disperse dye. In this case, the solvent is preferably DMF, and the temperature of the solvent (or of the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 85-105°C, preferably about 95°C.

[0067] According to a specific example, the textile material comprises polyester fibers and further comprises at least one cellulose material, preferably cotton fibers. For example, the textile material may comprise at least 50%, preferably 60%, more preferably 70% by weight of polyester fibers and further comprise cellulose fibers, for example at most 50%, preferably 40%, more preferably 30% by weight of cotton fibers.

[0068] According to embodiments, at least a portion of the cellulose fibers in the textile material are dyed. According to embodiments, all of the cellulose fibers in the textile material are dyed. According to embodiments, the textile material comprises cellulose fibers with a plurality of dyes, for example, a plurality of vat dyes.

[0069] According to a specific embodiment, the textile material comprises dyed cellulose fibers, preferably dyed cotton fibers. The dyed cellulose fibers comprise at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, sulfur dyes, and mixtures thereof. According to a specific embodiment, the textile material comprises dyed cellulose fibers, preferably dyed cotton fibers, and the solvent is preferably a mixture of DMF, water, and a base (optionally containing a reducing agent). In other words, in a specific embodiment, the solvent is preferably a mixture of DMF and alkaline water (optionally containing a reducing agent). Suitable reducing agents are selected from the group consisting of alkali metal hydrosulfites, sulfites, thiosulfates, and oxalates; thiourea dioxide; alkali metal sulfoxylate formaldehyde, hydroxyacetone, and derivatives of sulfinic acid. For example, the reducing agent is NaSO. Suitable bases are NaOH, KOH, and mixtures thereof.

[0070] According to a specific example, the textile material comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers, at least some of the polyester fibers being dyed with at least one disperse dye and at least some of the cotton fibers being dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water comprising a base and optionally a reducing agent, and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in step b) in the extraction chamber and after the first centrifugation in the washing step in the centrifuge is in the range of 85 to 110°C, preferably about 95°C.

[0071] According to a specific example, the textile material comprises polyester fibers and further comprises a polyurethane material, preferably elastane, and at least one cellulose material, preferably cotton, more preferably cotton fibers. For example, the textile material may comprise at least 50%, preferably 60%, more preferably 70% by weight of polyester fibers and further comprise elastane and cellulose fibers, for example at most 50%, preferably 40%, more preferably 30% by weight of elastane and cotton fibers.

[0072] According to a specific example, the textile material comprises at least 50%, preferably 60%, more preferably 70% by weight of polyester fibers and elastane fibers and at most 50%, preferably 30%, by weight of cotton fibers and elastane fibers, and at least some of the polyester fibers are dyed with at least one disperse dye, and at least some of the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water comprising a base and optionally a reducing agent, and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in step b) in the extraction chamber and in the washing step in the centrifuge after the first centrifugation is in the range of 95 to 105°C, preferably about 100°C.

[0073] According to a specific example, the textile material comprises at least 90% by weight of cotton fibers and at most 10% by weight of elastane fibers, at least a portion of the cotton fibers being dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water comprising a base and optionally a reducing agent, and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in the extraction chamber in step b) and in the washing step in the centrifuge after the first extraction is in the range of 95-105°C, preferably about 100°C.

[0074] According to a specific example, the textile material consists of cotton fibers (i.e., 100% cotton), and at least a portion of the cotton fibers have been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water comprising a base and optionally a reducing agent, and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in the extraction chamber in step b) and in the washing step in the centrifuge after the first extraction is in the range of 85-110°C, preferably about 95°C.

[0075] According to an embodiment, the textile material may comprise a vat dye, optionally a plurality of vat dyes. According to an embodiment, the textile material may comprise a mixture of disperse and vat dyes.

[0076] According to a specific embodiment, the textile material comprises a vat dye different from indigo, and the solvent (or solution comprising the solvent and the extracted substances) further comprises water and a base, and optionally a reducing agent. Advantageously, the presence of the reducing agent allows the reduction of the vat dye to the corresponding leuco form, which allows the vat dye to be easily removed from the textile.

[0077] In a specific example, the vat dye is indigo. Advantageously, when the vat dye is indigo, it is not necessarily required that water, a base, and a reducing agent be present together with the solvent. In other words, the indigo is removed by a solvent (DMF, DMAC, or a mixture thereof) or by a solution comprising the solvent and the extracted substance, thereby not necessarily requiring the presence of water and a reducing agent. However, in a specific example, the vat dye is indigo and the solvent (or the solution comprising the solvent and the extracted substance) further comprises water, a reducing agent, and a base.

[0078] According to a specific embodiment, the textile material comprises at least one cellulosic material, preferably cotton, more preferably cotton fibers, and indigo.

[0079] In an embodiment, the solution obtained in steps b) and / or c) is used as a solvent for extracting dyes from other batches of textile material up to 20 times, preferably up to 30 times, more preferably up to 40 times.

[0080] In a specific example, when multiple extraction steps are performed (each extraction is performed in a different extraction chamber), the solvent (or a solution comprising the solvent and extracted material) is used for up to 20, preferably up to 40, and more preferably up to 60 extraction cycles, i.e., for 20, preferably 40, and more preferably 60 batches of textile waste. For example, if three extraction chambers are used, the solvent would be used 20 times for the first extraction chamber (e.g., depending on the dye concentration of the textile waste), and the solvent used in the second and third extraction chambers would also be used 20 times in the second and third extraction chambers. After the dye in the solvent (i.e., the solution comprising the solvent and extracted material) reaches a concentration that impairs further dye extraction, the solvent in the second extraction chamber (which has already been used 20 times) is fed to the first extraction chamber and used again, for example, 20 times. Similarly, the solvent in the third chamber (which has already been used 20 times) is fed to the second extraction chamber and used again, for example, 20 times. For example, after the solvent has been used for 60 extractions, the extraction of the dye is impaired.

[0081] According to a specific example, the solution obtained in steps b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are repeated until the amount of extracted dye in the solution comprising the solvent and the extracted material reaches a concentration that impairs further dye extraction.

[0082] According to a specific example, the solution obtained in steps b) and / or c) is used as a solvent for extracting dye and optionally polyurethane (preferably elastane) from another batch of textile material, and steps b) and c) are repeated until the solution comprising the solvent and the extracted substances reaches a viscosity that impairs further dye extraction.

[0083] As used herein, "dye extraction is impaired" means that the solvent used in the extraction process (i.e., in the first extraction chamber) is no longer able to reduce the amount of dye in the textile waste. This is verified by checking the concentration of the dye in the solvent (i.e., the concentration of the dye in the solution comprising the solvent, dye, and extracted materials). In other words, at this point, the solvent is saturated and has reached the limit of its extraction capacity based on the content of dye and non-PET materials. The saturation level of the solvent is measured by periodically analyzing samples taken from the desaturated solution tank 9 and / or samples taken along the line of Plant A.

[0084] According to a particular embodiment, during step b), the solvent or a solution comprising the solvent and the extracted substance enters the extraction chamber, circulates through the textile material and leaves the extraction chamber.

[0085] According to a specific embodiment, during step b), the rotation of the extraction chamber is stopped and the solvent or a solution comprising the solvent and the extracted substance is circulated into the extraction chamber, through the textile material and out of the extraction chamber in order to extract the textile material. In this embodiment, the textile material, e.g., fabric or garment or fabric, is contained in a non-moving, i.e., stationary, extraction chamber.

[0086] Another object of the invention resides in an apparatus (or plant) A for removing dyes from textile materials in a method according to the invention, comprising at least one extraction chamber 2 adapted to treat the textile material with a solvent, at least one centrifuge 3 for separating a solution comprising the solvent and extracted substances from the textile material, at least one storage tank 6 for fresh solvent, and at least one distillation device 5, wherein the storage tank 6 for fresh (i.e. clean) solvent is provided with duct lines adapted to supply clean solvent to the extraction chamber 2 and the centrifuge 3 and duct lines adapted to receive solvent from the distillation device 5, and the distillation device is adapted to receive the solution comprising the solvent and extracted substances from the centrifuge 3.

[0087] According to a specific embodiment, the extraction chamber is configured to rotate horizontally during operation, thereby agitating the textile material within the extraction chamber. In a specific embodiment, the extraction chamber rotates about its horizontal axis and includes a baffle, so that the textile material is moved along the horizontal axis from an entry point into the extraction chamber to an exit point on the opposite side of the extraction chamber during the extraction process. According to a specific embodiment, the extraction chamber 2 does not rotate and includes an impeller for agitating the textile material within the extraction chamber during operation; preferably, the impeller is a paddle-type impeller having paddles distributed along its shaft.

[0088] According to a specific embodiment, the device further comprises at least one storage tank 7 (see FIG. 3) configured to receive the mixture of textile material and solvent from the extraction chamber, e.g. after step b) of the method, and to feed the textile material to a centrifuge, e.g. for carrying out step c).

[0089] According to a specific example, the apparatus may further comprise at least one non-saturated solvent storage tank configured to supply the solvent, i.e., the solution comprising the solvent and the extracted substance, to the extraction chamber and configured to receive the solution comprising the solvent and the extracted substance from the extraction chamber and / or from the storage tank and / or from the centrifuge.

[0090] According to an embodiment, the apparatus further comprises at least one distillation device 5 configured to receive a solution comprising the solvent and extracted substances from the extraction chamber and to separate the extracted substances from the solvent. Preferably, the solution comprising the solvent and extracted substances is fed to the distillation device when the amount of extracted substances in the solution comprising the solvent and extracted substances reaches a concentration at which further dye extraction is impaired. In an embodiment, a suitable pressure value in the distillation device is 15 to 90 mbar, preferably 20 to 85 mbar, and most preferably 40 to 80 mbar.

[0091] According to a specific embodiment, the apparatus comprises a plurality of extraction chambers 2a-2d and a plurality of centrifuges 3a-3d; the extraction chambers and centrifuges are arranged in series, and the apparatus further comprises means for feeding the textile material along the series of extraction chambers and centrifuges to provide a flow of textile material, wherein at least one centrifuge is associated with an extraction chamber in an upward direction with respect to the textile flow and another extraction chamber in a downward direction with respect to the textile flow.

[0092] According to a preferred embodiment, the centrifuge 3 is selected from a vertical peeler-type bottom-discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, and a decanter-type centrifuge. Preferably, the centrifuge comprises a filter wall arranged on a rotating drum to retain the fabric pieces, a solvent supply line, and a scraper. The scraper is for removing the wet fabric pieces (which precipitate as a thin layer or as a ring-shaped cake after centrifugation) from the inner wall of the centrifuge. As mentioned above, the extraction chamber preferably has stirring means, such as an impeller, rotating around its horizontal axis or rotating inside, is thermally insulated, and is directly connected to the centrifuge by a duct D to supply the mixture of solvent and fabric pieces obtained after the extraction process to the centrifuge. According to a preferred embodiment, a duct line 14 is provided for supplying clean solvent from the clean solvent tank 6 to the centrifuge 3 for the aforementioned washing process with hot solvent in the centrifuge 3 after the centrifugation process has been carried out. Advantageously, a filter 11 is arranged on the outlet duct to retain the fibers and pieces present in the solvent exiting the centrifuge 3.

[0093] Apparatus A also comprises a quality control unit 10, in which the amount of dye present in the treated textile pieces after centrifugation and washing, but before drying, is measured. The amount of dye still present in the textile is determined according to techniques known per se in the art, for example, color measurement using a spectrophotometer, i.e., Datacolor. If the dye is still present in the textile in unacceptable amounts, the textile material is returned to the extraction chamber and extracted again according to step b) of the method of the present invention. If the dye has been sufficiently removed from the textile, the textile is transferred to a drying unit 4. In a preferred embodiment, a washing device is provided upstream of the drying unit to remove the solvent, i.e., DMF, from the treated textile pieces by washing them with water.

[0094] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to a specific embodiment, each extraction chamber is connected to the next extraction chamber in a path for transporting the fabric from the first extraction chamber to the next extraction chamber by a solvent supply means, and the solvent supply means is configured to supply the solution comprising the solvent and extracted substances leaving each extraction chamber to the preceding extraction chamber.

[0095] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to an embodiment, the last extraction chamber in the series is connected to a fresh solvent storage tank, which is configured to supply fresh solvent to the last extraction chamber.

[0096] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to a specific embodiment, the apparatus may further comprise a plurality of storage tanks, each storage tank being arranged with respect to the fabric flow downward relative to the extraction chamber and upward relative to the centrifuge (i.e., between the extraction chamber and the centrifuge), and / or each storage tank being arranged with respect to the centrifuge and downward relative to the extraction chamber.

[0097] Further aspects and advantages of the present invention will be discussed in more detail with reference to the accompanying drawings, which provide non-limiting examples.

[0098] In Figures 1 to 3, the solid arrows generally represent the flow of textile material, and the dotted arrows generally represent the flow of solvent and / or solution comprising solvent and extracted substances.

[0099] Referring to the exemplary embodiment of Figure 1, fabric waste is collected and pre-processed to reduce the size of the fabric in a fabric size reduction device 1. For example, fabric size reduction device 1 may be a cutter or other machine suitable for reducing fabric and garments to pieces having reduced size, clipping, or a machine suitable for converting fabric and / or garments into fibers. The size of the fabric pieces has been disclosed earlier in this specification: a green-blue polyester fabric sample reduced to pieces at least 90% having a size in the range of 2.0-2.5 mm is shown in Figure 5 as 1.

[0100] After size reduction pretreatment, the textile material is transferred to extraction chamber 2. For example, the extraction chamber may be selected from a single or double shaft mixer, a wash screw, a washing machine-like reactor, or a solvent-based cleaning machine. In a specific embodiment, extraction chamber 2 has a horizontal rotating shaft and a rotating drum; in a specific embodiment, the extraction chamber is equipped with a rotating impeller, preferably a paddle-like impeller.

[0101] In the extraction chamber 2, the textile material, i.e., the pieces of fabric, are extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances (the extracted substances including at least the dye and, if initially present in the textile, the polyurethane material). In the extraction chamber, the textile material is agitated, for example, by rotating the extraction chamber 2 or by an impeller without rotating the extraction chamber 2, for at least part of the extraction process, and preferably for the entire extraction process.

[0102] According to a specific example, the extraction step b) has a duration of 2 to 20 minutes, preferably 5 to 15 minutes, more preferably 7.5 to 12.5 minutes, most preferably 10 minutes.

[0103] According to a specific example, the temperature of the solvent (or the solution comprising the solvent and the extracted substance) in the extraction chamber 2 ranges from 80 to 140° C., preferably from 82 to 135° C. A preferred solvent is DMF, optionally containing an aqueous base solution depending on the dye to be removed.

[0104] Advantageously, the conditions of the extraction step b) are adjusted depending on the composition of the textile material to be treated.

[0105] For example, if the textile material is in the form of 100% PET fabric and / or clippings dyed with at least one disperse dye, the solvent is preferably DMF and the temperature of the solvent in extraction chamber 2 is in the range of 85-105°C, preferably about 100°C. For example, if the textile material is in the form of 100% PET fibers dyed with at least one disperse dye, the solvent is preferably DMF and the temperature of the solvent in extraction chamber 2 is in the range of 80-110°C, preferably about 85-105°C. For example, if the textile material is in the form of clippings (i.e., pieces of fabric and / or clothing) made of polyester fibers, at least a portion of the polyester fibers are dope-dyed. In this case, the solvent is preferably DMF and the temperature of the solvent (or solution comprising the solvent and the extracted substance) used in step b) in extraction chamber 2 is in the range of 80-140°C, preferably about 85-130°C. For example, when the textile material comprises at least 90% by weight of polyester fibers and at most 10% by weight of elastane fibers dyed with at least one disperse dye, the solvent is preferably DMF, and the temperature of the solvent in the extraction chamber 2 is in the range of 85 to 105°C, preferably about 95°C. For example, when the textile material comprises at least 70% by weight of polyester fibers and at most 30% by weight of cotton fibers or a mixture of cotton fibers and elastane, the polyester fibers are dyed with at least one disperse dye, and the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is preferably a mixture of DMF and water containing a reducing agent and a base, and the temperature of the solvent in the extraction chamber 2 is in the range of 95 to 105°C, preferably about 100°C.

[0106] For example, when the textile material comprises at least 90% by weight of cotton fibers and at most 10% by weight of elastane fibers, and the cotton fibers have been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is preferably a mixture of DMF and water containing a reducing agent and a base, and the temperature of the solvent in the extraction chamber 2 is in the range of 95 to 105°C, preferably about 100°C. For example, when the textile material comprises cotton fibers (i.e., 100% cotton), and the cotton fibers have been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is preferably a mixture of DMF and water containing a reducing agent and a base, and the temperature of the solvent in the extraction chamber 2 is in the range of 85 to 110°C, preferably about 95°C.

[0107] After step a), a solution comprising the solvent and the extracted substances (i.e. at least one extracted dye and optionally extracted polyurethane substances, such as elastane) is obtained together with the treated textile.

[0108] In a specific example, the solution comprising the solvent and extracted substances is recirculated during step b) by moving in and out of the extraction chamber 2 both while the fabric is being agitated in the extraction chamber 2 or while agitation of the fabric in the extraction chamber 2 is discontinued, i.e., while both the fabric and the extraction chamber 2 are maintained in a stationary (i.e., static) state.

[0109] According to a specific embodiment, at the end of step b), the mixture of textile and solvent is transferred to a centrifuge 3 in order to remove the solution comprising the solvent remaining in the textile and the extracted substances according to step c). Preferably, the centrifuge 3 is different from the extraction chamber. In a specific embodiment, the centrifugation is carried out in the extraction chamber. For example, if the extraction chamber is a washer or a solvent clarifier, the extraction chamber can carry out the centrifugation and drying. In a specific embodiment, the extraction, centrifugation, washing and drying are carried out in one machine, for example, a solvent clarifier; the same machine can further comprise a distillation unit.

[0110] In a specific example, the solvent not absorbed by the fabric is removed from the extraction chamber 2 and provided to a solvent storage tank 9. The solvent storage tank 9 is further configured to receive the solvent removed from at least the centrifuge 3 and, optionally, the drying device 4. The solvent in the solvent storage tank 9 is typically a solution of the solvent and the extracted substances. The solvent (or the solution comprising the solvent and the extracted substances) is provided from the solvent storage tank 9 to the extraction chamber 2.

[0111] According to a specific embodiment, the centrifugation is carried out at a G-force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. In a specific embodiment, after centrifugation, the solution of solvent and extracted substances is returned to the extraction chamber 2 for processing another batch of textile material, i.e. a new batch of textile material.

[0112] In a specific example, after centrifugation, the textile material may be washed in centrifuge 3. The washing is carried out, for example, using fresh, i.e., clean, solvent or a fresh mixture of solvent, water, reducing agent, and base, depending on the material to be washed. The fresh solvent or a fresh mixture of solvent, water, reducing agent, and base is fed from centrifuge 3 via line 14 to fresh solvent tank 6 (see FIG. 4). The clean solvent washing step is carried out at the temperature at which extraction is carried out in extraction chamber 2. Thus, the clean solvent is fed to centrifuge 3, which is heated to the hot washing temperature. The washed material is centrifuged again to remove the solvent used for washing. The used solvent or the mixture of solvent, water, reducing agent, and base is recovered and preferably transferred to extraction chamber 2 for processing another batch of textile material.

[0113] According to FIG. 1, after centrifugation the textile material is dried in a drying device 4 .

[0114] When the extracted materials in the solution comprising the solvent and extracted materials reach a concentration at which the solvent is saturated and further dye extraction is impaired, the solution comprising the solvent and extracted materials is fed to a saturated solution tank, which feeds the distillation apparatus 5, thereby separating the solvent from the extracted materials. The distilled solvent is then transferred to a fresh solvent tank 6 for storage. When required, fresh solvent is fed from the fresh solvent tank 6 to at least the extraction chamber 2, for example, to adjust the fabric:solvent bath ratio. As described above, fresh solvent can be fed from the fresh solvent tank 6 to the centrifuge 3 to perform the washing of the textile.

[0115] In one embodiment, the textile material is selected from polyester fibers, fabrics made of polyester fibers, fabric clippings made of polyester fibers, and polyester fibers ground to polyester powder, at least some of the polyester fibers are dyed with at least one disperse dye, the solvent is DMF, and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber 2 and in the centrifuge washing step after the first extraction is in the range of 80 to 110°C, preferably 85 to 110°C, and preferably about 95°C for the fabric, fabric clippings, and polyester powder.

[0116] In one embodiment, the textile material is a clipping made of polyester fibers, at least some of which are dope dyed, the solvent is DMF, and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and in the centrifuge washing step after the first centrifugation is in the range of 80 to 140°C, preferably 85 to 130°C.

[0117] In one embodiment, the textile material comprises at least 90% by weight of polyester fibers and at most 10% by weight of elastane fibers, wherein at least some of the polyester fibers are dyed with at least one disperse dye, the solvent is DMF, and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and in the centrifuge washing step after the first centrifugation is in the range of 85-105°C, preferably about 95°C.

[0118] In one embodiment, the textile material comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers, wherein at least a portion of the polyester fibers are dyed with at least one disperse dye and at least a portion of the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is a mixture of DMF and water comprising at least one base and optionally at least one reducing agent, and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and in the washing step in the centrifuge after the first centrifugation is in the range of 85-110°C, preferably about 95°C.

[0119] FIG. 2 shows a schematic diagram of an embodiment of the method and apparatus of the present invention, which includes two extraction chambers (2a and 2b) and two centrifuges.

[0120] Referring to the non-limiting example of Figure 2, in a textile size reduction apparatus 1, textile waste is collected and pretreated for textile size reduction. The pre-treated textile material is transferred to a first extraction chamber 2a. In the extraction chamber 2a, the textile material is extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances, wherein the extracted substances include at least one dye. Preferably, when the apparatus comprises more than one extraction chamber, the solvent used in the first extraction chamber is the solution comprising the solvent and extracted substances obtained in the second extraction chamber after the second extraction step b) performed on a previous batch of treated textile. The textile material is agitated in the extraction chamber 2a, for example, by rotating the extraction chamber 2a or by an impeller without rotating the extraction chamber 2a, for at least part of the extraction step, and preferably for the entire extraction step.

[0121] In a specific example, the resulting solution comprising the solvent and extracted substances is recirculated during step b) by flowing in and out of the first extraction chamber 2a, both during agitation of the fabric in the extraction chamber 2a or while agitation of the fabric in the extraction chamber 2a is interrupted, i.e., while both the fabric and the extraction chamber 2a are maintained in a stationary (i.e., static) state.

[0122] According to a specific embodiment, at the end of step b), the textile is transferred from the first extraction chamber 2a to a first centrifuge 3a in order to remove the solution comprising the solvent and extracted substances remaining in the textile according to step c). According to a specific embodiment, the centrifugation is carried out at a G-force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. In a specific embodiment, after centrifugation, the solution comprising the solvent and extracted substances is fed back to the extraction chamber 2 for processing another batch of textile material.

[0123] After centrifugation, the textile material is transferred from the first centrifuge 3a to the second extraction chamber 2b. In the second extraction chamber 2b, the textile material is further extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances (the extracted substances include at least one dye). Preferably, if the apparatus includes more than one extraction chamber, the solvent used in the second extraction chamber may be fresh solvent. The textile material is agitated in the extraction chamber 2b, for example, by rotating the extraction chamber 2b or by an impeller without rotating the extraction chamber 2b, for at least part of the extraction process, preferably for the entire extraction process.

[0124] 1, and referring to FIG. 2, in an embodiment, solvent not captured by the fabric is recovered from extraction chambers 2a and 2b and supplied to at least one solvent storage tank (not shown). The at least one solvent storage tank is further configured to receive solvent removed from at least centrifuges 3a and 3b and, optionally, from drying device 4. The solvent in the solvent storage tanks is generally a solution comprising the solvent and the extracted substances. The solvent (or solution comprising the solvent and the extracted substances) is supplied from the at least one solvent storage tank to extraction chambers 2a and 2b.

[0125] In a specific example, in a multi-extraction method, fresh solvent is supplied to all extraction chambers at the start of the method (i.e., to process the first batch of textile waste), and the solvent is reused in the same extractor until a saturation point is reached, i.e., a concentration condition at which the extracted material in the solvent becomes impaired, e.g., after extraction of at least 20 batches, preferably at least 30 batches, more preferably at least 40 batches, e.g., 50 batches.

[0126] In a specific example, the resulting solution comprising the solvent and extracted substances is recycled during step b) by flowing in and out of the second extraction chamber 2b both during agitation of the fabric in the extraction chamber 2b or during interruptions in agitation of the fabric in the extraction chamber 2b, i.e., while both the fabric and the extraction chamber 2b are maintained in a stationary (static) state.

[0127] At the end of step b), the textile is transferred from the second extraction chamber 2b to a second centrifuge 3b in order to remove the solution comprising the solvent and extracted substances remaining in the textile according to step c). In a specific example, after centrifugation, the solution of solvent and extracted substances is returned to the extraction chamber 2b for processing another batch of textile material.

[0128] Preferably, the solution comprising the solvent and extracted substances obtained in the second extraction chamber 2b after one or more extraction steps is fed to the first extraction chamber 2a for extracting another batch of textile.

[0129] In a specific example, after centrifugation in the second centrifuge 3b, the textile material may be washed with hot cleaning solvent in the second centrifuge 3b. The washed material is centrifuged to remove the solvent used for washing. The solvent, or a mixture of solvent, water, and reducing agent and base, is recovered and preferably transferred to the second extraction chamber 2b for processing another batch of textile material.

[0130] According to FIG. 2, after centrifugation in the second centrifuge 3 b the textile material is dried in a drying device 4 .

[0131] When the extracted materials in the solution comprising the solvent and extracted materials reach a concentration such that the solvent is saturated and further dye extraction is impaired, the solution comprising the solvent and extracted materials is fed from the first extraction chamber 2a and / or the first centrifuge 3a to a distillation apparatus 5, which separates the solvent from the extracted materials. The distilled solvent is then transferred to a fresh solvent tank 6 for storage. If desired, fresh solvent can be fed from the fresh solvent tank 6 to at least the second extraction chamber 2b to adjust the fabric:solvent bath ratio. As described above, fresh solvent can be fed from the fresh solvent tank 6 to the second centrifuge 3b to wash the textile. Optionally, fresh solvent can also be fed from the fresh solvent tank 6 to the first centrifuge 3a to wash the textile.

[0132] FIG. 3 shows a schematic diagram of an embodiment of the method including multiple (four) extraction chambers and multiple (four) centrifuges.

[0133] 3 shows a plurality of storage tanks, specifically a plurality of first storage tanks 7a, 7b, 7c, 7d and a plurality of second storage tanks 8a, 8b, 8c, 8d, one first storage tank 7a, 7b, 7c, 7d is provided after each extraction chamber 2a, 2b, 2c, 2d, and one second storage tank 8a, 8b, 8c, 8d is provided after each centrifuge 3a, 3b, 3c, 3d.

[0134] According to a specific example, the textile material obtained in step b), i.e. the textile material after extraction with the solvent, can be transferred from the extraction chamber 2a, 2b, 2c, 2d to the first storage tank 7a, 7b, 7c, 7d, for example when the centrifuge 3a, 3b, 3c, 3d cannot hold the entire amount of textile material to be processed in the reaction chamber 2a, 2b, 2c, 2d, the textile material obtained in step b) can be transferred from the extraction chamber 2a, 2b, 2c, 2d to the first storage tank 7a, 7b, 7c, 7d, so that a further batch of textile material can be extracted in the extraction chamber 2a, 2b, 2c, 2d and at the same time the centrifugation of the textile material obtained in step b) can be completed.

[0135] In the embodiment of Figure 3, the textile material leaving the centrifuges 3a, 3b, 3c, 3d is transferred to second storage tanks 8a, 8b, 8c, 8d. The material in the first three second storage tanks 8a, 8b, 8c is then fed to the subsequent extraction chambers (i.e., extraction chambers 2b, 2c, 2d) for further extraction. The textile material in the last second storage tank 8d is free or substantially free of dyes and possible polyurethanes and is subjected to drying.

[0136] In a specific example, the solution comprising the solvent and extracted substances obtained in each extraction chamber is recirculated during step b) by entering and exiting the same extraction chamber both during agitation of the fabric in the extraction chamber or while agitation of the fabric in the extraction chamber is discontinued, i.e., while both the fabric and the extraction chamber are maintained in a stationary (i.e., static) state.

[0137] In a specific example, after centrifugation, the solution of solvent and extracted substances is returned to the preceding extraction chamber for processing another batch of textile material. For example, referring to Figure 3, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3a is returned to extraction chamber 2a, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3b is returned to extraction chamber 2b, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3c is returned to extraction chamber 2c, and the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3d is returned to extraction chamber 2d.

[0138] According to the embodiment of FIG. 3, the solvent used in the last extraction chamber 2d may be fresh solvent. After extraction, a solution containing the solvent and extracted substances is obtained. In particular, after the solvent used in the first extraction chamber 2a, i.e., the solution containing the solvent and extracted substances, reaches a concentration such that further dye extraction is impaired, and the solution containing the solvent and extracted substances is transferred from the first extraction chamber 2a to a distillation apparatus, the solution containing the solvent and extracted substances obtained in the last (fourth) extraction chamber may be supplied to the preceding (third) extraction chamber 2c for the third extraction step of the subsequent batch of textile, and the solution containing the solvent and extracted substances obtained in the last (fourth) extraction chamber 2d may be supplied to the preceding (third) extraction chamber 2c for the third extraction step of the next batch of textile. The solution containing the solvent and extracted substances obtained in the third extraction chamber 2c may be supplied to the preceding (second) extraction chamber 2b for the second extraction step of the next batch of textile. The solution containing the solvent and extracted substances obtained in the second extraction chamber 2b may be fed to the preceding (first) extraction chamber 2a for the first extraction step of the next batch of textile. Advantageously, the amount of dye in the textile gradually decreases from the first extraction chamber 2a to the last extraction chamber 2d, while the concentration of the extracted substances, in particular the dye, in the solvent used in the extraction step (i.e., the solution comprising the solvent and extracted substances) decreases from the first extraction chamber 2a to the last extraction chamber 2d. In other words, the solution containing the solvent and extracted substances obtained in the last (fourth) extraction chamber 1d is fed to the third extraction chamber 2c for the third extraction step of the next batch of textile, after the solvent used in the first extraction chamber 2a is fed to a distillation apparatus, and the solvent used in the second extraction chamber 2b is fed to the first extraction chamber 2a, and the solvent used in the third extraction chamber 2c is fed to the second extraction chamber 2b.

[0139] Figure 4 shows an embodiment of the method and apparatus of the present invention, in which the raw material is shown to be dyed polyester-elastane textile waste; however, the apparatus disclosed with reference to the illustrative embodiment of Figure 4 is suitable for all suitable textile materials in accordance with the present invention.

[0140] In the embodiment of Figure 4, a batch of dyed polyester-elastane textile waste (both pre-consumer, post-industrial and post-consumer) is provided. The textile material is mechanically processed to obtain clippings or small pieces having dimensions of 1 to 50 mm, preferably 2 to 10 mm, more preferably 2 to 2.5 mm, depending on the nature of the fibers present in the fabric. The textile material in the form of small clippings is provided to an extraction chamber 2. In the extraction chamber, the textile material is extracted with a solvent to obtain a solution comprising the solvent and the extracted substances (in this case, dye and elastane). The liquor ratio of textile:solvent (kg:l) is preferably 1:10 to 1:20, preferably 1:13 to 1:15.

[0141] After extraction, the mixture of solvent and textile material is transferred along duct D to centrifuge 3. In the centrifuge, the textile material is centrifuged to separate the mixture of solvent and extracted materials from the textile material. After solvent removal in the centrifuge, the textile pieces undergo a washing step. Preferably, washing is carried out at the temperature required for extraction in the centrifuge using a hot cleaning solvent supplied to the interior of the centrifuge using solvent supply line 14. During washing, the centrifuge is rotated at a reduced speed, i.e., a speed effective for washing the textile pieces, preferably in the range of 300 to 700 rpm, more preferably 400 to 600 rpm. Washing is preferably carried out for a time period in the range of 3 to 10 minutes, more preferably about 5 to 6 minutes, which is sufficient to remove residual dye. After washing, the textile is again centrifuged to remove any remaining solvent used in the washing step remaining on the textile. The final concentration of solvent in the fabric pieces after centrifugation is typically about 4-7% by weight, which offers the advantage of having a thin layer of fabric "cake" adhering to the side walls of the centrifuge (i.e., a layer of compressed fabric pieces deposited along the walls of the centrifuge, providing a central free area). Such a layer of compressed fabric pieces can be easily removed from the walls, for example, by a scraper mounted on the centrifuge door and a hopper that receives the peeled wet fabric pieces (which includes a screw that feeds the collected fabric pieces out of the centrifuge).

[0142] After the centrifugation and washing steps, a quality control unit 10 determines the amount of dye (and possibly elastane) still present in the fabric according to techniques known per se. If dye (and / or elastane) is still present in the fabric in unacceptable amounts, the textile material is returned to the extraction chamber for re-extraction. If the dye has been sufficiently removed from the fabric, the fabric is dried in a drying device 4.

[0143] The dried woven polyester material with reduced dimensions is now ready to be subjected to thermomechanical processing to provide recycled PET chips, which is not the object of the present invention; the clean woven material is stored in a stock area.

[0144] The "process line" according to Figure 4 shows diagrammatically the course along which textile material is conducted according to the method and plant of Figure 4. The solution of solvent and extracted substances recovered from the centrifuge, after filtration in solvent filter 11, and the solution of solvent and extracted substances resulting from drying the textile, are sent to a non-saturated solution tank 9. If the amount of extracted dye (and elastane) in the solution comprising solvent and extracted substances is not at a concentration that would impair the extraction of further dye and / or elastane (i.e., the solution is "non-saturated"), the solution is fed back to the extraction chamber for extracting subsequent batches of textile material. If the amount of extracted dye (and elastane) in the solution comprising solvent and extracted substances is at a concentration that would impair the extraction of further dye and / or elastane (i.e., the solution is "saturated"), the solution is transferred to a "saturated storage tank" and then fed to a distillation apparatus 5, where the solvent is separated and recovered from the extracted substances (e.g., dye, elastane, and any finishing chemicals). The term "saturated" refers to a solution or solvent that has reached the limit of its extraction capacity based on the input content of non-PET materials. The saturation level is analyzed by periodic sampling from a storage tank containing the non-saturated solution and / or by in-line in-house measurement. The solvent after distillation, i.e., "fresh" solvent, is stored in a clean solvent storage tank 6. Fresh solvent is provided from the storage tank to the extraction chamber for extracting the textile material and to the centrifuge for washing the textile material after centrifugation. The "non-saturated solution line" according to FIG. 4 generally indicates the path followed by the solution of solvent and extracted materials whose concentration would impair further dye and / or elastane extraction. The "solution (post-saturated) line" generally indicates the path followed by the solution of solvent and extracted materials whose concentration would impair further dye and / or elastane extraction according to the method and plant of FIG. 4. The "clean solution line" according to FIG. 4 shows schematically the path taken by the solvent (ie the solvent recovered after distillation) through the process and plant of FIG.

[0145] FIG. 5 shows an embodiment of the method and apparatus of the present invention, corresponding to that of FIG. 4, and further including a washing unit 13 for washing the treated textile pieces with water, located upstream of a drying unit 4 for recovering the solvent, i.e., DMF. The washing with water may be carried out in a centrifuge 3. The water containing DMF or other solvent is supplied to a water-solution tank 12 for storage. From tank 12, the water-solvent solution is fed to a distillation column 15 to separate the solvent from the water. The solvent is fed to a clean solvent tank 6, and the distilled water is fed to a distilled water tank 16 for storage before further use in the method. In addition to the flow lines shown in FIG. 4, FIG. 5 shows wash water lines and a water-solution line.

[0146] 4 and 5 thus show that the apparatus or plant of the present invention is a fully closed loop plant for a closed loop process whereby the solvent (including water) used is completely recovered and reused in the process. In fact, it has generally been found that 99.9% of the solvent is recovered and reused.

[0147] FIG. 6 is a photograph showing the reduction in dye content from the initial polyester material of reduced size (reference number 1) to the same material after extraction (reference number 2), to the extracted material after further hot washing in a centrifuge (reference number 3), and to the extracted material after undergoing a final extraction in an extraction chamber and washing (reference number 4).

[0148] The present invention will now be further described with reference to the following non-limiting examples. [Example]

[0149] (impeller stirring only) 100 g of textile waste (100% PET dyed with disperse dyes) was ground to obtain a fine powder. The powder was placed in an extractor and 600 ml of solvent (DMF) was added. The extraction chamber was heated to 90-100°C and stirred with a mechanical stirrer (impeller). Extraction was completed in 10 minutes, and the powder was directly transferred to a centrifuge to remove the solvent from the powder under thermal conditions. A vertical centrifuge was used at 1250 G-force for 2-3 minutes. The sample was then transferred to a dryer. All powder was obtained in a dry state at 75°C for 10 minutes. All solvents recovered in the extraction, centrifugation, and drying processes were pooled together, and the pooled solvent was used for extracting a new batch in the same extractor. [Example]

[0150] (Agitation by rotating the extraction chamber + solvent circulation) Five kilograms of 100% PET textile waste (garment) dyed with disperse dye was placed in an extractor. After adding 50 L of solvent (DMF) to the extractor (i.e., extraction chamber), the extraction chamber was heated to 95°C and rotated horizontally for 15 minutes at an average rotation speed of 50 rpm. To increase extraction efficiency, the solvent was circulated during extraction. Excess solvent was recollected before and after the centrifugation process, which was carried out under thermal conditions (80-90°C) and relatively high G-force for 2-3 minutes. Because garments have a small surface area compared to fabrics, yarns, and fibers, a second extraction is necessary to remove all the dye on the textile waste (generally depending on the dye concentration on the textile). Therefore, the textile waste (from the first extraction) was sent to a second extraction chamber. All parameters of the extraction and centrifugation processes were the same. After the second centrifugation, the textile was dried at 75-80°C for 10 minutes. The solvent from the first extraction and first centrifuge tank was collected and sent to the first extraction tank for the extraction of a new batch, and the solvent from the second extraction and second centrifuge tank was sent to the second extraction tank for the extraction of a new batch. [Example]

[0151] (Agitation by rotating the extraction chamber + solvent circulation) 100 g of 100% cotton fabric waste dyed with vat and reactive dyes was placed in an extractor, and the extraction chamber was heated to 90-95°C. 1 L of solvent (DMF) was added to the extractor, and the fabric was held there for 10 minutes. After 10 minutes of extraction and solvent circulation by horizontal rotation of the extraction chamber, the fabric was directly fed into a centrifuge, and the solvent was removed at 1200 G-force for 2-3 minutes. The fabric was then fed into a second extractor, where 1 L of DMF and water (in the presence of a reducing agent and a base) was poured, and the remaining dye was removed at 90-95°C for 10 minutes. After the second centrifugation process, a drying process was carried out at 80-90°C. The solvent was recollected and reused as is in subsequent examples. [Example]

[0152] (large-scale production) 400 kg of 100% PET textile waste dyed with a light brown disperse dye was processed through a manufacturing protocol for closed-loop extraction and recycled PET chip production. The textile waste was first mechanically processed to produce small pieces with dimensions ranging from 1 to 15 mm (at least 90% by mass of the treated textile had dimensions ranging from 2.0 to 2.5 mm). The material was then transferred to an insulated extraction chamber (tank) into which a solvent was added. The textile was agitated by rotating a paddle-type impeller housed within the extraction chamber around a horizontal axis, and the extraction process was carried out for 10 minutes at 90°C with a bath ratio of 1:14 (kilograms of textile:liters of solvent). The solvent was dimethylformamide (DMF). After extraction, the wet textile material containing the solvent was transferred directly to a centrifuge and dynamically centrifugally run for 240 seconds at a force ranging from 900 to 1300 g to remove excess extraction solvent. An additional washing step was applied using clean DMF solvent at 90°C for 6 minutes at 500 rpm to improve dye removal in the centrifuge. After washing, another centrifugation was performed to remove the solvent. Then, as the color reached the appropriate level, the centrifuged fabric was transferred to a drying unit (in a quality control unit / tank) to remove any remaining solution. After sufficient drying, the material was sent to a recycled PET chip production equipment for further processing. The extraction solution used throughout the process was recovered from both the centrifuge and drying stages and reused in a closed-loop system until saturation was reached. The saturated solution was then sent to a distillation plant for purification and reuse. Because the entire system operates in a closed loop, minimal solvent loss is guaranteed, maintaining a sustainable and efficient process. [Example]

[0153] (large-scale production) 400 kg of 100% PET textile scrap dyed with blue disperse dye was processed through the manufacturing protocol for closed-loop extraction and recycled PET chip production according to the process described in Example 4. The starting material is shown in Figure 6 as 1. The extracted textile piece is shown in Figure 6 as 2, and the textile material after centrifugation, washing and centrifugation is shown in Figure 6 as 3. After checking in the control unit, the treated textile material at 3 was fed again into the extraction chamber for further dye extraction. The textile material after the second extraction was centrifuged and dried, resulting in the material at 4 in Figure 6.

[0154] The claimed method and apparatus thus enable the removal of dyes from textile waste, in particular disperse dyes from polyester fibres and vat, reactive, pigment, direct and sulphur dyes from cotton fibres. The treated textiles are then recycled in a manner known per se. [Explanation of symbols]

[0155] (1) Fabric size reduction device (2) Extraction chamber (2a) First extraction chamber (2b) Second extraction chamber (2c) Third extraction chamber (2d) Fourth extraction chamber (3) Centrifuge (3a) First Centrifuge (3b) Second centrifuge (3a) No. 3 Centrifuge (3b) No. 4 centrifuge (4) Drying equipment (5) Distillation apparatus (6) Fresh solvent tank (7a)~(7c) First storage tank (8a)~(8b) Second storage tank (9) Unsaturated solution tank (10) Quality Control Unit (11) Filter (12) Water-solution tank (13) Cleaning equipment (14) Duct line (16) Distilled water tank

Claims

1. 1. A method for removing dyes from textile materials, in particular textile waste, wherein the textile material comprises dyes and 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, polyester fibres, or wherein the textile material comprises dyes and at least 80% by weight, preferably at least 90% by weight, cellulose fibres, the method comprising the following steps: a) providing a textile material and a solvent suitable for removing dye from the textile in an extraction chamber to provide a textile and solvent mixture; b) extracting the textile with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the textile material and the solvent are agitated in an extraction chamber during at least a portion of the extraction process, preferably during the entire extraction process; c) removing the solution comprising the solvent and extracted materials from the fabric. comprising the steps of: a1) reducing the textile material to pieces having a maximum dimension of 5 cm before providing the textile material to the extraction chamber; b1) after step b), feeding the mixture of solvent and fabric pieces to a means for carrying out step c), preferably a centrifuge; c1) applying a solvent to the fabric pieces after step c) to wash the fabric and remove the dye from the fabric. wherein the liquor ratio of fabric (kg):solvent (L) is in the range of 1:3 to 1:20, and the temperature of the solvent is in the range of 80 to 140°C in at least steps a), b) and c1).

2. 1. A method for removing dyes from textile materials, in particular textile waste, wherein the textile material comprises at least 50%, preferably at least 60%, more preferably at least 70% by weight of polyester fibres, or the textile material comprises at least 80%, preferably at least 90% by weight of cellulose fibres, the method comprising the following steps: a) providing a batch of textile material to an extraction chamber; b) extracting a batch of textile material with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the textile material and solvent are agitated in an extraction chamber during at least a portion of the extraction process, preferably during the entire extraction process; c) removing the solution comprising the solvent and extracted materials from the fabric. wherein the solution comprising the solvent and the extracted substances obtained in steps b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are repeated, preferably for a predetermined number of cycles or until the amount of extracted substances in the solution comprising the solvent and the extracted substances reaches a concentration at which further dye extraction is impaired.

3. 3. The method according to claim 1 or 2, wherein the extraction chamber containing the solvent and the textile material is rotated about its horizontal axis or an agitator is rotated within the extraction chamber containing the solvent and the textile material, thereby agitating the textile material during at least part of the extraction process, preferably during the entire extraction process.

4. 3. The method according to claim 1 or 2, wherein step c) comprises separating the solution comprising the solvent and the extracted substances from the textile by centrifugation, wherein step c) is preferably carried out in a centrifuge selected from a vertical peeler-type bottom discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, a decanter-type centrifuge.

5. 5. The method of claim 4, wherein after step c) clean solvent is supplied to the fabric present in the centrifuge and the step of hot solvent washing of the fabric is carried out in the centrifuge, wherein the centrifuge is rotated at a speed lower than the centrifugation speed.

6. 6. The method of claim 5, wherein after the hot solvent washing step and before the drying step, the textile material is washed with water to remove the solvent.

7. 3. The method according to claim 1 or 2, wherein prior to the step of providing the textile material to the extraction chamber, the textile material is divided into pieces by mechanical treatment, at least 90% of the pieces having a dimension of 1 to 50 mm, preferably 2 to 10 mm, more preferably 2 to 2.5 mm, or at least 90% of the pieces having a dimension in the range of 20 to 50 mm.

8. 3. The method according to claim 1 or 2, wherein the extraction chamber is a first extraction chamber, and wherein after the first extraction step b), the textile material is fed from the first extraction chamber to a first centrifuge for the first removal step c), from the first centrifuge to a second extraction chamber for the second extraction step b), and from the second extraction chamber to a second centrifuge for the second extraction step c), so that the first and second extraction steps b) and the removal step c) are carried out in two different extraction chambers and two different centrifuges, respectively, and preferably the solvent removed from the first extraction chamber and / or the second centrifuge is fed to the first extraction chamber.

9. 9. The method of claim 8, wherein steps b) and c) are repeated two or more times in two or more extraction chambers and centrifuges, and the solvent removed from any extraction chamber different from the first chamber is supplied to the preceding extraction chamber.

10. 3. The method of claim 1 or 2, wherein the solvent used in step b) is in the form of a solution comprising the solvent and extracted substances, the extracted substances including at least the dye.

11. 3. The method according to claim 1 or 2, wherein the solvent is DMF or DMAC or a mixture of DMF or DMAC with alkaline water or a mixture thereof, and preferably the temperature of the solvent or the solution comprising the solvent and the extracted substance in the extraction chamber is in the range of 80 to 140°C, preferably 82 to 135°C.

12. 3. The method according to claim 1 or 2, wherein the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 10 to 1 / 20.

13. 3. The method according to claim 1 or 2, wherein step c) is carried out in a centrifuge at a G-force of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for a time of 0.5 to 10 minutes, preferably 1 to 5 minutes.

14. the textile comprises polyester fibres and further comprises at least one polyurethane material, preferably elastane; preferably the textile material comprises at least 90% by weight of polyester fibres and at most 10% by weight of elastane fibres; at least a portion of the polyester fibres have been dyed with at least one disperse dye, the solvent is DMF, the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber and optionally in step c1) is in the range of 85-105°C, preferably 95°C, and before the step of providing the textile to the extraction chamber, the textile material has been reduced to pieces by mechanical treatment, at least 90% of the pieces having a dimension of 2.0-2.5 mm; or the textile comprises polyester fibres and further comprises at least a cellulose material, preferably cotton, more preferably cotton fibres, preferably 3. The method according to claim 1 or 2, wherein the textile material comprises at least 50%, preferably 70%, by weight of polyester fibres and at most 50%, preferably 30%, by weight of cotton fibres, at least a portion of the polyester fibres being dyed with at least one disperse dye and at least a portion of the cotton fibres being dyed with a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulphur dyes, the solvent is a mixture of DMF and water comprising at least one base and optionally at least one reducing agent, the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber is in the range of 85 to 110°C, preferably 95°C, and prior to the step of providing the textile to the extraction chamber, the textile material is reduced to pieces by mechanical treatment, and at least 90% of the pieces have a size in the range of 2.0 to 50 mm, preferably 20 to 50 mm.

15. the textile material comprises polyester fibers and further comprises at least one polyurethane material, preferably elastane, and at least a cellulose material, preferably cotton, more preferably cotton fibers, the textile material preferably comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers, at least a portion of the polyester fibers have been dyed with at least one disperse dye, and at least a portion of the cotton fibers have been dyed with a dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is a mixture of DMF and water comprising at least one base and optionally at least one reducing agent, the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and optionally in step c1) is in the range of 95 to 105°C, preferably about 100°C, and before the step of providing the textile to the extraction chamber, the textile material is divided into pieces by mechanical treatment, at least 90% of the pieces having a dimension of 20 mm or more, preferably 20 to 50 mm; or 3. The method according to claim 1 or 2, wherein the textile material comprises at least 90% by weight of cotton fibres and at most 10% by weight of elastane fibres, at least a portion of the cotton fibres have been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulphur dyes, the solvent is a mixture of DMF and water comprising a base and optionally at least one reducing agent, the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber and optionally in step c1) is in the range of 95 to 105°C, preferably about 100°C, and prior to the step of providing the textile to the extraction chamber, the textile material is divided into pieces by mechanical treatment, and at least 90% of the pieces have a dimension of 20 mm or more, preferably 20 to 50 mm.

16. 3. The method according to claim 1 or 2, wherein the textile material consists of cotton fibres, at least a portion of which has been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulphur dyes, the solvent is a mixture of DMF and water comprising at least one base and optionally at least one reducing agent, and the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber and optionally in step c1) is in the range of 85 to 110°C, preferably about 95°C.

17. 3. The method according to claim 1 or 2, wherein the solution obtained in step b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are repeated up to 20 times, preferably up to 40 times, more preferably up to 60 times using the solution as solvent.

18. 3. The apparatus (A) for removing dyes from textiles, preferably fabrics, according to claim 1 or 2, comprising at least one extraction chamber (2) adapted to treat the textile material with a solvent, at least one centrifuge (3) for separating a solution comprising the solvent and extracted substances from the textile material, at least one fresh solvent storage tank, and at least one distillation apparatus (5; 15), means (1) for reducing the size of the textile into pieces by mechanical treatment, means for feeding the textile pieces and solvent to the extraction chamber, duct means (D) for feeding the mixture of solvent and textile pieces from the extraction chamber (2) to the centrifuge (3), and means (12) for feeding the solvent to the centrifuge (3) for carrying out the washing step, preferably wherein at least the extraction chamber (2) and the duct means (D) for feeding the mixture of textile and solvent to the centrifuge (3) are provided with insulating means for thermally insulating them, more preferably wherein all parts of the apparatus for containing the solvent or the mixture of textile and solvent are thermally insulated.

19. 19. The apparatus according to claim 18, wherein the fresh solvent storage tank (6) is configured to supply fresh solvent to the extraction chamber and to receive the solvent from the distillation device (5; 15), and the distillation device is configured to receive a solution comprising the solvent and the extracted substances from the extraction chamber (2) and / or the centrifuge (3) and to separate the extracted substances from the solvent; and the apparatus optionally comprises at least one storage tank (7a-7d) configured to receive the textile material from the extraction chamber (2) and to supply it to the centrifuge (3); preferably, the centrifuge is selected from a vertical peeler-type bottom discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, a decanter-type centrifuge.

20. 19. Apparatus according to claim 18, wherein the centrifuge (3) has vertical walls to which the fabric pieces stick after the solvent is removed by centrifugation, and comprises stripping means for removing the fabric pieces from the vertical walls of the centrifuge after centrifugation.

21. 19. The apparatus according to claim 18, comprising a plurality of extraction chambers (2a-2d) and a plurality of centrifuges (3a-3d), wherein the extraction chambers and centrifuges are arranged in series, and means for feeding the textile along the series of extraction chambers and centrifuges to provide a textile flow, wherein at least one centrifuge is connected, directly or indirectly, to an extraction chamber (2) above in relation to the textile flow and to another extraction chamber below in relation to the textile flow, preferably each extraction chamber being connected to the preceding extraction chamber by a solvent supply means configured to supply a solution comprising solvent and extracted substances leaving each extraction chamber to the preceding extraction chamber, and only the last extraction chamber in the series is connected to a fresh solvent storage tank, which is configured to supply solvent only to the last extraction chamber.

Images