PROCESS AND PLANT FOR REMOVING DYES FROM WASTE TEXTILES

Abstract

In a process for removing dyes from a textile material, comprising or consisting of polyester fibers, or comprising or consisting of cotton fibers, a batch of said textile material is reduced to clippings having small size, treated with a solvent under stirring in an extraction chamber and centrifugated to remove the solvent, the solution comprising solvent and extracted material is used as a solvent to extract dye from another batch of textile material.

Claims

1. A process for removing dyes from a textile material, said textile material including a dye and at least 50% by weight of polyester fibers, or said textile material comprising a dye and including at least 80% by weight of cellulosic fibers, said process comprising the following steps: a) providing said textile material and a solvent suitable to remove said dye from said textile in an extraction chamber to provide a mixture of textile and solvent; b) extracting said textile material with said solvent to provide a solution comprising said solvent and extracted material, said extracted material including at least said dye, wherein said extracting includes stirring said textile material and said solvent within said extraction chamber during at least part of said extraction step; c) removing said solution of said solvent and extracted material from said textile material, said process further comprising the steps of a1) reducing said textile material into pieces having maximum dimension of 5 cm prior to said step a) of providing; b1) after said step b), feeding said solution and said pieces of textile material to a centrifuge to perform said step c); and c1) feeding said solvent or a further solvent to said textile pieces after step c) to wash said textile and remove dye from said textile; wherein a bath ratio of textile (kg) to solvent (liters) is within the range of 1:3 (kg/l) to 1:20 (kg/l) and wherein at least in said steps a), b) and c1) the temperature of said solvent is in the range of 80 C. to 140 C.

2. A process for removing dyes from a textile material, wherein said textile material includes at least 50% by weight of polyester, or wherein said textile material includes at least 80% by weight of cellulosic fibers, said process comprising the steps of: a) providing a batch of said textile material in an extraction chamber; b) extracting said batch of said textile material with a solvent to provide a solution comprising said solvent and extracted material, said extracted material including at least a dye, wherein said extracting includes stirring said textile material and said solvent within said extraction chamber during at least part of said extracting step; and c) removing said solution of solvent and extracted material from said textile material; wherein said solution comprising solvent and extracted material of said step b) and/or said step c) is used as a solvent to extract dye from another batch of textile material, and wherein said steps b) and c) are repeated for a preset number of cycles or until an amount of extracted material in said solution comprising solvent and extracted material reaches a concentration whereby further dye extraction is impaired.

3. The process according to claim 1, wherein said extracting includes rotating said extraction chamber containing said solvent and textile material around its horizontal axis, or wherein said stirring includes rotating stirring means within said extraction chamber containing said solvent and textile material, whereby said textile material is stirred within said extraction chamber during the entire extracting step.

4. The process according to claim 1, wherein said step c) includes separating said solution comprising said solvent and said extracted material from said textile by centrifuging and is carried out in said centrifuge said centrifuge selected from the group consisting of a vertical peeler type bottom discharge centrifuge, a horizontal peeler type centrifuge, a horizontal pusher type centrifuge, and a decanter type centrifuge.

5. The process according to claim 4, wherein, after said step c) clean solvent is fed to the textile material present in said centrifuge and a hot solvent washing step of said textile material is carried out in said centrifuge, wherein said centrifuge is rotated at a speed lower than a centrifugation speed.

6. The process according to claim 5, wherein after said hot solvent washing step said textile material is washed with water to remove solvent before a drying step.

7. The process according to claim 1, wherein said textile material is reduced by mechanical treatment into pieces, at least 90% of said pieces having size in a range of 1 mm to 50 mm before said step a) of providing.

8. A process according to claim 1, wherein said textile material, after said extraction step b), is fed from said extraction chamber to a first centrifuge for said removal step c), and further comprising feeding said textile material from said first centrifuge to a further extraction chamber for a further extraction step b) and from said further extraction chamber to a second centrifuge for a further removal step c), whereby said extraction step b) and said further extraction step b) and said removal step c) and said further removal step c) are carried out in two different extraction chambers and two different centrifuges, respectively, wherein solvent removed from the further extraction chamber and/or said second centrifuge is fed to said extraction chamber.

9. A process according to claim 1, wherein steps b) and c) are repeated more than twice in more than two said extraction chambers and centrifuges, and wherein the solvent removed from any said extraction chamber except a first extraction chamber of said more than two said extraction chambers, is fed to the previous extraction chamber.

10. The process according to claim 1, wherein said solvent used in said step b) is in the form of solution comprising said solvent and extracted material including at least a dye.

11. The process according to claim 1, wherein said solvent comprises Dimethylformamide (DMF) or Dimethylacetamide (DMAC), or a mixture of DMF or DMAC with alkali water, or mixtures thereof and the temperature of said solution comprising solvent and extracted material in said extraction chamber is in a range of 80 C. to 140 C.

12. The process according to claim 1, wherein a bath ratio of said textile material/solvent is in a range from to 1/20 kg/liter.

13. The process according to claim 1, wherein said step c) is carried out in said centrifuge at a g-force in a range of from 250 to 5000 for a time in a range of 1 to 5 minutes.

14. The process according to claim 1, wherein said textile material comprises polyester fibers and further comprises at least a polyurethane material; said textile material comprises at least 90% by weight of said polyester fibers and at most 10% by weight of elastane fibers, wherein at least part of said polyester fibers is dyed with at least one disperse dye, wherein said solvent is DMF, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber is in a range of from 85 C. to 105 C., wherein prior to said step a) of providing said textile material is reduced by mechanical treatment into pieces, at least 90% of said pieces having size from 2.0 mm to 2.5 mm; or wherein said textile comprises polyester fibers and further comprises at least a cellulosic material, said textile material comprises at least 50%, by weight of polyester fibers and at most 50% by weight of cotton fibers, wherein at least part of said polyester fibers is dyed with at least one disperse dye and wherein at least part of said cotton fibers is dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, wherein said solvent is a mixture of DMF and water comprising at least one base or a mixture of DMF and water comprising at least one base and at least one reducing agent, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber is in the range of from 85 C. to 110 C., wherein prior to said step a) of providing said textile material said textile material is reduced by mechanical treatment into pieces, at least 90% of said pieces having size from 2.0 mm to 50 mm.

15. The process according to claim 1, wherein said textile material comprises polyester fibers and further comprises elastane and at least a cellulosic material comprising cotton-fibers, wherein said textile material comprises at least 50% by weight of said polyester fibers and at most 50% by weight of said cotton fibers and said elastane fibers, wherein at least part of said polyester fibers is dyed with at least one disperse dye and wherein at least part of said cotton fibers is dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, wherein said solvent is a mixture of DMF and water comprising a base or a mixture of DMF and water comprising a base and at least one reducing agent, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber and optionally in said step c1) is in a range of 95 C. to 105 C., wherein prior to said step of providing said textile material, said textile material is reduced by mechanical treatment into pieces, at least 90% of said pieces having size from 2.0 mm to 50 mm; or wherein said textile material comprises at least 90% by weight of cotton fibers and at most 10% of elastane fibers, wherein at least part of said cotton fibers is dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, wherein said solvent is a mixture of DMF and water comprising a base or a mixture of DMF and water comprising a base and at least one reducing agent, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber is in the range of from 95 C. to 105 C., wherein prior to said step of providing said textile material to said extraction chamber, said textile material is reduced by mechanical treatment into pieces, at least 90% of said pieces having size above 20 mm.

16. The process according to claim 1, wherein said textile material comprises cotton fibers, wherein at least part of said cotton fibers is dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, wherein said solvent is a mixture of DMF and water comprising at least a base or a mixture of DMF and water comprising a base and at least one reducing agent, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber is in a range of from 85 C. to 110 C.

17. The process according to claim 1, wherein said solution obtained in step b) and/or c) is used as the solvent to extract dye from another batch of textile material, and wherein said steps b) and c) are repeated using said solution as said solvent up to 20 times.

18. An apparatus for removing dyes from a textile comprising at least one extraction chamber configured to treat a textile material with a solvent, at least one centrifuge for separating a solution comprising said solvent and extracted material from said textile material, at least one fresh solvent storage tank and at least one distillation device, means to reduce the size of said textile material by mechanical treatment into textile pieces, means to feed said textile pieces and said solvent to said at least one extraction chamber, duct means for feeding a mixture of solvent and textile pieces from said at least one extraction chamber to said at least one centrifuge and means to feed said solvent to said at least one centrifuge to carry out a washing step, wherein said at least one extraction chamber and said duct means for feeding said mixture to said at least one centrifuge are provided with insulation that thermally insulates them.

19. The apparatus according to claim 18, wherein said at least one fresh solvent storage tank is configured to feed said fresh solvent to said at least one extraction chamber, and configured to receive said solvent from said distillation device, and wherein said distillation device is configured to receive said solution comprising said solvent and extracted material from said at least one extraction chamber and/or from said at least one centrifuge, to separate said extracted material from said solvent; said apparatus comprising at least one storage tank, configured to receive said textile material from said at least one extraction chamber and to feed said textile material to said at least one centrifuge.

20. The apparatus according to claim 18, wherein said at least one centrifuge has a lateral wall to which said textile pieces adhere after solvent removal by centrifugation, and further includes a scraper to remove the textile pieces from said lateral wall of the centrifuge after centrifugation.

21. The apparatus according to claim 18, wherein said apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, wherein said extraction chambers and said centrifuges are arranged in a series, and means for feeding said textile material along said series of extraction chambers and centrifuges to provide a flow of textiles, wherein at least one said centrifuge is connected, directly or indirectly, with an extraction chamber of said plurality of extraction chambers upstream with respect to the flow of textiles and is connected to another extraction chamber of said plurality of extraction chambers downstream with respect to said flow of textiles, each said extraction chamber being connected to a previous extraction chamber of said plurality of extraction chambers with solvent feeding means, said solvent feeding means being configured to feed said solution comprising said solvent and extracted material exiting from each said extraction chamber to said previous extraction chamber and wherein only the last extraction chamber of said series is connected to a first fresh solvent storage tank of said at least one fresh solvent storage tank, said fresh solvent storage tank being configured to feed said solvent to said last extraction chamber only.

22. The process according to claim 2, wherein said extracting includes rotating said extraction chamber containing said solvent and textile material around its horizontal axis, or wherein said stirring includes rotating stirring means within said extraction chamber containing said solvent and textile material, whereby said textile material is stirred within said extraction chamber during the entire extracting step.

23. The process according to claim 2, wherein said step c) includes separating said solution of said solvent and said extracted material from said textile by centrifuging and is carried out in a centrifuge selected from the group consisting of a vertical peeler type bottom discharge centrifuge, a horizontal peeler type centrifuge, a horizontal pusher type centrifuge, and a decanter type centrifuge.

24. The process according to claim 23, wherein, after said step c) clean solvent is fed to the textile material present in said centrifuge and a hot solvent washing step of said textile material is carried out in said centrifuge, wherein said centrifuge is rotated at a speed lower than a centrifugation speed.

Description

[0109] Further aspects and advantages in accordance with the present disclosure will be discussed more in detail with reference to the enclosed drawings, given by way of non-limiting example, wherein:

[0110] FIG. 1 shows a schematic representation of an embodiment of the process and apparatus of the invention including one extraction chamber and one centrifuge;

[0111] FIG. 2 shows a schematic representation of an embodiment of the process and apparatus of the invention including two extraction chambers and two centrifuges;

[0112] FIG. 3 shows a schematic representation of an embodiment of the process including four extraction chambers and four centrifuges;

[0113] FIG. 4 shows a schematic representation of an embodiment of the process and apparatus of the invention, including a mechanical treatment of the textiles before extraction and the quality control unit;

[0114] FIG. 5 shows a schematic representation of an embodiment of the process and apparatus of the invention, including a washing unit for the textiles after the quality control unit;

[0115] FIG. 6 is a photograph showing the aspect of textile material (small pieces of polyester fabric) at different steps of the process.

[0116] In FIGS. 1 to 3, continuous arrows schematically represent the flow of the textile material while dashed arrows schematically represents the flow of the solvent and/or the solution comprising solvent and the extracted material.

[0117] With reference to the exemplary embodiment of FIG. 1, the waste textile material is collected and pre-treated to reduce the size of the textile in a textile size reduction device 1. For example, the textile size reduction device 1 can be a cutter or other machine, suitable for reducing fabrics and garments into pieces having a reduced size, i.e., clippings, or a machine suitable for converting fabrics and/or garments into fibers. The size of the pieces of fabric has been previously disclosed in the description: a sample of green-blue polyester fabric reduced to pieces having a size that is at least 90% in the range 2.0 mm to 2.5 mm is shown under reference 1 in FIG. 5.

[0118] The textile material, after size-reduction pre-treatment, is moved to an extraction chamber 2. For example, the extraction chamber may be selected from single/double shaft mixer, wash screw, washing machine like reactors, cleaning machines using solvent. In embodiments, extraction chamber 2 has a horizontal rotation axis and a rotating drum; in embodiments the extraction chamber is provided with a rotating impeller, preferably a paddle-like impeller.

[0119] In extraction chamber 2, the textile material, namely the fabric pieces, is extracted (treated) with a solvent, to provide a solution comprising solvent and extracted material, said extracted material including at least a dye and polyurethanic material if initially present on the textile. The textile material is stirred within said extraction chamber 2, e.g., by rotating the extraction chamber 2 or by means of an impeller without rotating the extraction chamber 2, during at least part of said extracting step, preferably during the entire extraction step.

[0120] According to embodiments, extraction step b) has a duration of from 2 minutes to 20 minutes, preferably from 5 min to 15 min, more preferably from 7.5 min to 12.5 min., most preferably 10 min.

[0121] According to embodiments, the temperature of the solvent (or the solution comprising solvent and extracted material) in the extraction chamber 2 is in the range of from 80 C. to 140 C., preferably from 82 C. to 135 C. Preferred solvent is DMF optionally including an aqueous basic solution, according to the dyes to be removed.

[0122] Advantageously, the conditions of the extraction step b) can be adjusted according to the composition of the textile material to be treated.

[0123] For example, when the textile material is in the form of 100% PET fabrics and/or clippings, dyed with at least one disperse dye, the solvent is preferably DMF, and the temperature of said solvent in said extraction chamber 2 may be in the range of from 85 C. to 105 C., preferably about 100 C. For example, when 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 said solvent in said extraction chamber 2 may be in the range of from 80 C. to 110 C., preferably from 85 C. to 105 C. For example, when the textile material is in the form of clippings (i.e., pieces of fabrics and/or garments) consisting of polyester fibers, and at least part of said polyester fibers is dope-dyed. In this case, the solvent is preferably DMF, and the temperature of said solvent (or said solution comprising solvent and extracted material) used in said step b) in said extraction chamber 2 may be in the range of from 80 C. to 140 C., preferably from 85 C. to 130 C. For example, when the textile material comprises at least 90% by weight of polyester fibers, dyed with at least one disperse dye, and at most 10% by weight of elastane fibers, the solvent is preferably DMF, and the temperature of said solvent in said extraction chamber 2 may be in the range of from 85 C. to 105 C., and preferably is 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 of a mixture of cotton fibers and elastane, and the polyester fibers are dyed with at least one disperse dye, and the cotton fibers are dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, the solvent is preferably a mixture of DMF and water comprising a reducing agent and a base, and the temperature of said solvent in said extraction chamber 2, is in the range of from 95 C. to 105 C., preferably about 100 C.

[0124] For example, when the textile material comprises at least 90% by weight of cotton fibers and at most 10% of elastane fibers, and the cotton fibers is dyed with at least a 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 reducing agent and a base, and the temperature of said solvent in said extraction chamber 2, is in the range of from 95 C. to 105 C., preferably about 100 C. For example, when the textile material consists of cotton fibers (i.e., it is 100% cotton), and the cotton fibers are dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, the solvent is preferably a mixture of DMF and water comprising a reducing agent and a base, and the temperature of said solvent in said extraction chamber 2, is in the range of from 85 C. to 110 C., preferably about 95 C.

[0125] After step b) a solution comprising solvent and extracted material (i.e., at least one extracted dye and, optionally, extracted polyurethane materials such as elastane) is obtained, together with treated textiles.

[0126] In embodiments, solution comprising solvent and extracted material can be recirculated during step b), by exiting and entering the extraction chamber 2, both during stirring of the textiles within the extraction chamber 2 or during interruption of the stirring of the textiles within the extraction chamber 2, i.e., while keeping both the textiles and the extraction chamber 2 in a static (i.e., still) condition.

[0127] According to embodiments, at the end of step b), the mixture of textiles and solvent are moved to a centrifuge 3 for removal of the residual solution comprising solvent and extracted material in the textiles, according to step c). Preferably centrifuge 3 is different from the extraction chamber. In embodiments, centrifuging can be carried out in the extraction chamber. For example, when the extraction chamber is a washing machine or a solvent cleaning machine, the extraction chamber may perform centrifugation and drying. In embodiments, extraction, centrifugation, washing, drying can be performed in one machine, e.g., in a solvent cleaning machine; the same machine can further include a distillation unit.

[0128] In embodiments, the solvent that has not been picked up by the textiles can be removed from the extraction chamber 2 and fed 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, from the drying device 4. The solvent in the solvent storage tank 9 is generally a solution comprising solvent and extracted material. The solvent (or the solution comprising solvent and extracted material) can be fed from the solvent storage tank 9 to the extraction chamber 2.

[0129] According to embodiments, centrifugation is carried out at g-force in the range of from g-force from 250 to 5000, preferably from 800 and 2000, more preferably from 900 to 1300, for a time in the range of from 0.5 to 10 minutes, preferably from 1 to 5 minutes. In embodiments, after centrifugation, the solution of solvent and extracted material is moved back to the extraction chamber 2 for treating another batch of textile material, e.g., a new batch of textile material.

[0130] In embodiments, after centrifugation, the textile material may be washed within the centrifuge 3. The washing can be performed, for example, using fresh, i.e. clean, solvent or a fresh mixture of solvent, water, a reducing agent and a base, according to the material to be washed. The fresh solvent or fresh mixture of solvent, water, a reducing agent and a base, are fed to the centrifuge 3 from the fresh solvent tank 6 with line 14 (see FIG. 4). The washing step with clean solvent is carried out at the temperature at which the extraction is carried out in extraction chamber 2. Thus clean solvent is fed to centrifuge 3 heated to the temperature required to reach such 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, a reducing agent and a base is recovered and preferably moved to the extraction chamber 2 for treating another batch of textile material.

[0131] According to FIG. 1, after centrifugation, the textile material is dried in a drying device 4.

[0132] When the extracted material in the solution comprising solvent and the extracted material reaches a concentration whereby the solvent is saturated and further dye extraction is impaired, the solution comprising solvent and extracted material is fed to a saturated solution tank and from this tank to distillation device 5, whereby said solvent is separated from said extracted material. Distilled solvent is, then, moved to fresh tank solvent 6 for storage. When required, fresh solvent can be fed from the fresh solvent tank 6 to at least the extraction chamber 2, for example, to adjust the bath ratio textile:solvent. As above mentioned, fresh solvent can be fed from the fresh solvent tank 6 to the centrifuge 3 to perform washing of the textiles.

[0133] In an embodiment said textile material is selected from polyester fibers, fabrics consisting of polyester fibers, fabric clippings consisting of polyester fibers, polyester fibers ground into polyester powder, wherein at least part of said polyester fibers is dyed with at least one disperse dye, wherein said solvent is DMF, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber and in the step of washing in the centrifuge after a first centrifugation, is in the range of 80 C. to 110 C., preferably from 85 C. to 105 C. for polyester fibers and is in the range of from 85 C. to 110 C., preferably about 95 C. for said fabrics, fabric clippings and polyester powder.

[0134] In an embodiment said textile material is clippings consisting of polyester fibers, wherein at least part of said polyester fibers is dope-dyed, wherein said solvent is DMF, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber and in the step of washing in the centrifuge after a first centrifugation, is in the range of from 80 C. to 140 C., preferably from 85 C. to 130 C.

[0135] In an embodiment, said textile material comprises at least 90% by weight of polyester fibers and at most 10% by weight of elastane fibers, wherein at least part of said polyester fibers is dyed with at least one disperse dye, wherein said solvent is DMF, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber and in the step of washing in the centrifuge after a first centrifugation, is in the range of from 85 C. to 105 C., preferably about 95 C.

[0136] In an embodiment said 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 part of said polyester fibers is dyed with at least one disperse dye and wherein at least part of said cotton fibers is dyed with at least a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes, wherein said solvent is a mixture of DMF and water comprising at least one base and optionally at least one reducing agent, wherein the temperature of said solvent or said solution comprising solvent and extracted material in said extraction chamber and in the step of washing in the centrifuge after a first centrifugation, is in the range of from 85 C. to 110 C., preferably about 95 C.

[0137] FIG. 2 shows a schematic representation of an embodiment of the process and apparatus of the invention including two extraction chambers (2a and 2b) and two centrifuges.

[0138] With reference to the exemplary embodiment of FIG. 2, the waste textile material is collected and pre-treated to reduce the size of the textile in a textile size reduction device 1. The textile material, after size-reduction pre-treatment, is moved 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 solvent and extracted material, said extracted material including at least a dye. Preferably, when the apparatus incudes more than one extraction chamber, the solvent used in the first extraction chamber is the solution comprising solvent and extracted material obtained in the second extraction chamber after the second extraction step b) carried out on the previous batch of textiles that have been treated. The textile material is stirred within said extraction chamber 2a, e.g., by rotating the extraction chamber 2a or by means of an impeller without rotating the extraction chamber 2a, during at least part of said extraction step, preferably during the entire extraction step.

[0139] In embodiments, the obtained solution comprising solvent and extracted material can be recirculated during step b), by exiting and entering the first extraction chamber 2a, both during stirring of the textiles within the extraction chamber 2a or during interruption of the stirring of the textiles within the extraction chamber 2a, i.e., while keeping both the textiles and the extraction chamber 2 in a static (i.e., still) condition.

[0140] According to embodiments, at the end of step b), the textiles are moved from the first extraction chamber 2a to a first centrifuge 3a for removal of the residual solution comprising solvent and extracted material in the textiles, according to step c). According to embodiments, centrifugation is carried out at a g-force from 250 to 5000 preferably from 800 and 2000, more preferably from 900 to 1300, for a time in the range of from 0.5 to 10 minutes, preferably from 1 to 5 minutes. In embodiments, after centrifugation, the solution of solvent and extracted material is fed back to the extraction chamber 2 for treating another batch of textile material.

[0141] The textile material, after centrifugation, is moved from the first centrifuge 3a to a 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 solvent and extracted material, said extracted material including at least a dye. Preferably, when the apparatus incudes more than one extraction chambers, the solvent used in the second extraction chamber may be fresh solvent. The textile material is stirred within said extraction chamber 2b, e.g., by rotating the extraction chamber 2b or by means of an impeller without rotating the extraction chamber 2b, during at least part of said extracting step, preferably during the entire extracting step.

[0142] In analogy to the embodiment of FIG. 1, with reference to FIG. 2, in embodiments, the solvent that has not been picked up by the textiles can be removed from the extraction chambers 2a and 2b and fed to at least one solvent storage tank (not shown in the figures). The at least one solvent storage tank is further configured to receive the solvent removed from at least the centrifuges 3a and 3b and, optionally, from the drying device 4. The solvent in the solvent storage tank is generally a solution comprising solvent and extracted material. The solvent (or the solution comprising solvent and extracted material) can be fed from the at least one solvent storage tank to the extraction chambers 2a and 2b.

[0143] In embodiments, in multiple extraction process, all extraction chambers will be fed with fresh solvent in the beginning of the process (i.e., for treating the first batch of waste textiles) and the solvent will be re-used in the same extractors till reaching the saturation point, i.e., a condition wherein the extracted material in the solvent reach a concentration whereby further dye extraction is impaired, e.g., after extraction of at least 20 batches, preferably at least 30, more preferable at least 40, for example 50. Starting from the second batch of waste textile to be treated, fresh solvent is fed only to the last extraction chamber.

[0144] In embodiments, the obtained solution comprising solvent and extracted material can be recirculated during step b), by exiting and entering the second extraction chamber 2b, both during stirring of the textiles within the extraction chamber 2b or during interruption of the stirring of the textiles within the extraction chamber 2b, i.e., while keeping both the textiles and the extraction chamber 2b in a static (i.e., still) condition.

[0145] At the end of step b), the textiles are moved from the second extraction chamber 2b to a second centrifuge 3b for removal of the residual solution comprising solvent and extracted material in the textiles, according to step c). In embodiments, after centrifugation, the solution of solvent and extracted material is moved back to the second extraction chamber 2b for treating another batch of textile material.

[0146] Preferably, the solution comprising solvent and extracted material obtained after one or more extraction steps in the second extraction chamber 2b is fed to the first extraction chamber 2a to extract a different batch of textiles.

[0147] In embodiments, after centrifugation in the second centrifuge 2b, the textile material may be washed with hot clean solvent within the second centrifuge 3b. The washed material is centrifuged to remove the solvent used for washing. The solvent or the mixture of solvent, water and a reducing agent and a base is recovered and preferably moved to the second extraction chamber 2b for treating another batch of textile material.

[0148] According to FIG. 2, after the second centrifugation in the second centrifuge 3b, the textile material is dried in a drying device 4.

[0149] When the extracted material in the solution comprising solvent and an extracted material reach a concentration whereby the solvent is saturated and further dye extraction is impaired, the solution comprising solvent and extracted material is fed, from said first extraction chamber 2a and/or from said first centrifuge 3a, to a distillation device 5, whereby said solvent is separated from said extracted material. Distilled solvent is, then, moved to a fresh tank solvent 6 for storage. When required, fresh solvent can be fed from the fresh solvent tank 6 to at least the second extraction chamber 2b, for example, to adjust the bath ratio textile:solvent. As above mentioned, fresh solvent can be fed from the fresh solvent tank 6 to the second centrifuge 3b to perform washing of the textiles. Optionally, fresh solvent can be fed from the fresh solvent tank 6 to the first centrifuge 3a, to perform washing of the textile.

[0150] FIG. 3 shows a schematic representation of an embodiment of the process including a plurality (four) extraction chambers and a plurality (four) of centrifuges.

[0151] In the embodiment of FIG. 3, a plurality of storage tanks, particularly a plurality of first storage tanks 7a, 7b, 7c, 7d and a plurality of second storage tanks 8a, 8b, 8c, 8d are shown. 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.

[0152] According to embodiments, the textile material obtained in step b), i.e., the textile material after extraction with solvent, can be moved from extraction chambers 2a, 2b, 2c, 2d to first storage tanks 7a, 7b, 7c, 7d, for example, when the centrifuges 3a, 3b, 3c, 3d are not able to hold the entire amount of textile material treated in the reaction chambers 2a, 2b, 2c, 2d, the textile material obtained in step b) can be moved from the extraction chambers 2a, 2b, 2c, 2d to first storage tanks 7a, 7b, 7c, 7d so that a further batch of textile material can be extracted in the extraction chambers 2a, 2b, 2c, 2d, while the centrifugation of the textile material obtained in step b) is completed.

[0153] In the embodiment of FIG. 3, the textile material exiting from the centrifuges 3a, 3b, 3c 3d is moved to second storage tanks 8a, 8b,8c, 8d. The material in the first three second storage thanks 8a, 8b, 8c in then fed to the subsequent extraction chamber (i.e., extraction chamber 2b, 2c, 2d) for further extraction. The textile material in the last second storage tank 8d is free, or substantially free, of dye and possible polyurethane and is ready to be dried.

[0154] In embodiments, the solution comprising solvent and extracted material obtained in each extraction chamber can be recirculated during step b), by exiting and entering the same extraction chamber, both during stirring of the textiles within the extraction chamber or during interruption of the stirring of the textiles within the extraction chamber, i.e., while keeping the extraction chamber in a static (i.e., still) condition.

[0155] In embodiments, after centrifugation, the solution of solvent and extracted material is moved back to the previous extraction chamber for treating another batch of textile material. For example, with reference to FIG. 3, the solution of solvent and extracted material obtained after centrifugation in centrifuge 3a is moved back to extraction chamber 2a, the solution of solvent and extracted material obtained after centrifugation in centrifuge 3b is moved back to extraction chamber 2b, the solution of solvent and extracted material obtained after centrifugation in centrifuge 3c is moved back to extraction chamber 2c and the solution of solvent and extracted material obtained after centrifugation in centrifuge 3d is fed back to extraction chamber 2d.

[0156] According to the embodiment of FIG. 3, the solvent used in the last extraction chamber 2d may be fresh solvent. After the extraction, a solution including solvent and extracted material is obtained. The solution including solvent and extracted material obtained in the last (fourth) extraction chamber 2d may be fed to the previous (third) extraction chamber 2c, for the third extraction step of the subsequent batch of textiles, particularly, after that the solvent, i.e., solution comprising solvent and extracted material, used in first extraction tank 2a reached a concentration of extracted material whereby further dye extraction is impaired, and the solution comprising solvent and extracted material is moved from the first extraction chamber 2a to the distillation device. The solution including solvent and extracted material obtained in the third extraction chamber 2c may be fed to the previous (second) extraction chamber 2b, for the second extraction step of the subsequent batch of textiles. The solution including solvent and extracted material obtained in the second extraction chamber 2b may be fed to the previous (first) extraction chamber 2a, for the first extraction step of the subsequent batch of textiles. Advantageously, the amount of dye in the textile is progressively reduced from the first extraction chamber 2a to the last extraction chamber 2d, while the concentration of the extracted material, particularly dye, in the solvent (i.e., the solution comprising solvent and extracted material) used in the extraction steps decreases the first extraction chamber 2a to the last extraction chamber 2d. In other words, the solution including solvent and extracted material obtained in the last (fourth) extraction chamber 2d is sent to the third extraction chamber 2c, for the third extraction step of the subsequent batch of textiles, after that the solvent used in first extraction chamber 2a is sent to distillation device, and the solvent used in the second extraction chamber 2b is sent to the first extraction chamber 2a, and the solvent used in the third extraction chamber 2c is sent to the second extraction chamber 2b.

[0157] FIG. 4 shows an embodiment of the process and apparatus of the invention. In FIG. 4, it is indicated that the starting material is dyed polyester-elastane textile waste; however, process and apparatus disclosed with reference to the illustrative embodiment of FIG. 4 applies to all suitable starting textile materials according to the invention.

[0158] In the embodiment according to FIG. 4, a batch of dyed polyester-elastane textile waste material (both pre-consumer, post-industrial or post-consumer) is provided. The textile material is mechanically treated to obtain clippings, or small pieces, having size from 1 mm to 50, mm depending on the nature of the fibers present in the fabric, preferably from 2 mm to 10 mm, more preferably from 2 mm to 2.5 mm. The textile material in the form of small clippings of the above mentioned dimension is provided to extraction chamber 2. In the extraction chamber, the textile material is extracted with a solvent to provide a solution comprising solvent and extracted material (in this case, dye and elastane). The bath ratio (kg:liters) kg of textile to liters of solvent preferably is in the range of 1:10 to 1:20, preferably 1:13 to 1:15.

[0159] After the extraction, the mixture of solvent and textile material is moved to a centrifuge 3 along duct D. In the centrifuge, the textile material is centrifuged to separate the solution of solvent and extracted material from the textile material. A washing step is carried out on the textile pieces after solvent removal in the centrifuge. Preferably, the washing is carried out at the temperature required for extraction in the centrifuge using hot clean solvent that is fed to the inner part of the centrifuge by means of a solvent feeding line 14. During washing the centrifuge is rotated at a reduced speed, i.e. a speed that is effective to wash the textile pieces, preferably in the range of 300 to 700 rpm, preferably 400 to 600 rpm. The washing is preferably carried out for a time in the range of 3 to 10 minutes, more preferably about 5-6 minutes are enough to remove the remaining dye. After washing, the textiles are centrifuged again to recover the residual solvent on textiles used in washing step. The final content of solvent in the textile pieces after centrifugation is generally about 4-7% by weight: this provides the advantage of having a cake in the form of a thick layer, (i.e. a layer of compacted textiles pieces deposited along the wall of the centrifuge and providing a central free area) of small pieces of fabric that are adhering to the lateral wall of the centrifuge. Such layer of compacted textile pieces can be easily removed from said wall by, e.g., a scraper mounted on the door of the centrifuge and a hopper to receive the scraped-off wet textiles pieces including a screw feeding the collected textile particles outside the centrifuge.

[0160] After centrifugation and washing steps, quality control unit 10 determines the amount of dye (and possibly elastane) that may still be present in the textiles, according to techniques that are, per se, known in the art. If the dye (and/or elastane) is still present in the textiles in an unacceptable amount, the textile material is moved back to the extraction chamber to be extracted again. If the dye has been sufficiently removed from the textiles, the textiles are dried in a drying device 4.

[0161] The dried textile polyester material with reduced size is at this point ready to be subjected to a thermomechanical process to provide recycled PET chips, not an object of the present invention; the clean textile material may be stored in a stock area.

[0162] The process line according to FIG. 4, schematically shows the path that is followed by the textile material according to the process and plant of FIG. 4. The solution of solvent and extracted material recovered from centrifugation, after filtration in filter 11, and from drying of textile is sent to non saturated solution tank 9. If the amount of extracted dye (and elastane) in said solution comprising solvent and extracted material is not in a concentration whereby further dye and/or elastane extraction is impaired (i.e., the solution is non saturated), the solution is fed back to the extraction chamber to extract a subsequent batch of textile material. If the amount of extracted dye (and elastane) in said solution comprising solvent and extracted material is in a concentration whereby further dye and/or elastane extraction is impaired (i.e., the solution is saturated), the solution is moved to a saturated storage tank and then fed to a distillation device 5, wherein the solvent is separated from the extracted material (e.g., dye, elastane and any finishing chemical) and recovered. The term saturated refers to a solution or solvent that reached the end of its extraction capability based on input content non-PET material. The saturation level can be analyzed by periodic sampling from the storage tank containing non-saturated solution and/or by means of in-line in-house measurements. The solvent after distillation, i.e., fresh solvent, is stored in a clean solvent storage tank 6. Fresh solvent can be provided from the storage tank to the extraction chamber for extracting textile material and to the centrifuge for washing the textile material after centrifugation. The non-saturated solution line according to FIG. 4, schematically shows the path that is followed by the solution of solvent and extracted material wherein the concentration of the extracted material is so that further dye and/or elastane extraction is not impaired. The solution line (after saturation), schematically shows the path that is followed by the solution of solvent and extracted material wherein the concentration of the extracted material is so that further dye and/or elastane extraction is impaired, according to the process and plant of FIG. 4. The clean solution line according to FIG. 4, schematically show the path that is followed by the solvent (i.e., the solvent recovered after distillation), according to the process and plant of FIG. 4.

[0163] FIG. 5 shows an embodiment of the process and apparatus of the invention that corresponds to the process and apparatus of FIG. 4 and that further includes a washing device 13 located upstream of the drying unit 4 to remove the solvent, namely DMF, by washing the treated textile pieces with water. Said washing with water may be carried out in the centrifuge 3. The water containing DMF or other solvent is fed to a water-solution tank 12 where it is stored. From tank 12 the water-solvent solution is sent to distillation column 15 in order to separate the solvent from water; solvent is fed to clean solvent tank 6, distilled water is sent to a water tank 16 for storage before further use in the process. In addition to the flow lines shown in FIG. 4, FIG. 5 shows a washing water line and a water-solution line.

[0164] FIG. 4 and FIG. 5 thus provide evidence that the apparatus, i.e. the plant, of the present invention is a fully closed-loop plant for a closed-loop process whereby the solvent used (including water) is totally recovered and reused in the process. Actually it was found that typically 99.9% of the solvent is recovered and reused.

[0165] FIG. 6 visually shows the reduction in dye content from the initial polyester material in reduced size 1 to the same material after extraction, ref. 2, the extracted material 2 after hot washing in a centrifuge, ref. 3, and the washed material 3 after a final extraction in extraction chamber with reference 4.

[0166] The invention will be further illustrated by reference to the following non limiting examples.

Example 1 (Only Stirring, With Impeller)

[0167] 100 g of waste textiles (100% PET dyed with disperse dyes) were grinded to obtain fine powder. The powder was put into an extractor and 600 ml of solvent (DMF) were added. The extraction chamber was heated to 90-100 C. and stirred with mechanical stirrer (with impeller). Extraction was completed in 10 minutes and the powder was directly sent to centrifuge to remove solvent from powder in hot conditions. Vertical centrifuge was used for 2-3 min. at 1250 g-force. Afterwards, sample was sent to a dryer. In 10 minutes at 75 C. all powder is obtained as dry form. All solvents regain in extraction, centrifuge and drying processes were collected together in order to use the collected solvent in the same extractor for the extraction of a new batch.

Example 2 (Stirring by Rotation of the Extraction Chamber+Circulation of the Solvent)

[0168] 5 kg of 100% PET waste textiles dyed with disperse dyes (garments) were put into the extractor. After addition of 50 L solvent (DMF) into the extractor, the extraction chamber was heated up to 95 C. and the extractor (i.e., extraction chamber) is horizontally rotated for 15 min, at an average rotation speed of 50 rpm. The solvent was circulated during extraction to increase the extraction efficiency. The excess amount of solvent was re-collected before and after centrifuge process that was performed at hot condition (80-90 C.) for 2-3 min at relatively high g-forces. Since the garments have less surface area comparing to fabrics, yarn, and fibers second extraction is needed to remove all dyes on to the waste textiles (in general, it depends the concentration of the dyes on the textiles). Therefore, waste textiles (coming from the first extraction) were sent to second extraction chamber. All parameters in extraction and centrifuge processes were the same. After second centrifuge, textiles were dried at 75-80 C. for 10 min. The solvent exiting the first extraction and the first centrifuge tank was collected and sent to first extraction tank for the extraction of new batch. The solvent exiting from second extraction and second centrifuge tanks were also sent to second extraction tank for the extraction of new batch.

Example 3 (Stirring by Rotation of the Extraction Chamber+Circulation of the Solvent)

[0169] 100 g of 100% cotton waste textiles dyed with vat and reactive dyes were put into the extractor and extraction chamber was heated at 90-95 C. 1 L of solvent (DMF) was poured into the extractor and textiles were kept for 10 min. After 10 min. extraction with horizontal rotation of the extraction chamber and circulation of the solvent, textiles were sent directly to the centrifuge and solvent was removed at 1200 g-force for 2-3 min. Afterwards textiles were sent to second extractor and 1 L of DMF:water (in presence of reducing agent and base) were poured into it to remove remaining dyes at 90-95 C. for 10 min. Drying process at 80-90 C. were conducted after second centrifuge process. The solvents are re-collected and re-used as per the previous examples.

Example 4 (Scaled Up Production)

[0170] 400 kg of 100% PET textile waste dyed with light brown disperse dyes was processed through a closed-loop extraction and preparation protocol for recycled PET chip production. The textile waste was first mechanically treated to be reduced to small pieces having size in the range of 1-15 mm with at least 90% by weight of the treated textile having a dimension in the range of 2.0 mm to 2.5 mm. The material was then transferred to an insulated extraction chamber (a tank) where the solvent was fed. The extraction process was carried out at 90 C. for 10 minutes with a bath ratio of 1:14 (textile kg:solution liters), by rotating a paddle type impeller housed in the extraction chamber around its horizontal axis to stir the textiles. The solvent was dimethyl formamide (DMF). After extraction, the wet textile material including the solvent was transferred directly into a centrifuge, which was operated dynamically at a g-force in the range of from 900 to 1300 for 240 seconds to remove the excess extraction solution. An additional washing step was applied for 6 minutes at 500 rpm using clean DMF solvent at 90 C. to improve dye removal in the centrifuge. After washing, another centrifugation is carried out to remove solvent. The centrifugated textiles were then transferred to a drying unit as the color had reached the proper level (in quality control unit/tank), to remove residual solution. Once fully dried, the materials were sent to a recycled PET chip production facility for further processing. The extraction solution used throughout the process was recovered from both the centrifuge and the drying stage and reused in a closed-loop system until reaching saturation. The saturated solution was then sent to a distillation plant for purification and reuse. The entire system operates in a closed loop, ensuring minimal solvent loss and supporting sustainable, efficient processing.

Example 5 (Scaled Up Production)

[0171] 400 kg of 100% PET textile waste dyed with light blue disperse dyes were processed through a closed-loop extraction and preparation protocol for recycled PET chip production according to process described in example 4.

[0172] The initial material is shown in FIG. 6 under reference 1. The extracted textile pieces are shown in FIG. 6 under reference 2 and the textile material after centrifugation, washing and centrifugation is shown in FIG. 6 under reference 3. After checking in control unit, the treated textile material of reference 3 was sent again to the extraction chamber for further extraction of the dye. The textile material after said second extraction was centrifuged and dried to provide the material shown in FIG. 6 under reference 4.

[0173] The claimed process and apparatus thus allow to remove dyes from waste textiles, particularly disperse dyes from polyester fibers and vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes from cotton fibers. The resulting textiles may then be recycled in a way known per se.