NON-CORROSIVE PROCESS FOR CLEANING A RECYCLABLE MATERIAL

Abstract

The invention relates to a non-corrosive process for cleaning a recyclable material comprising the following steps: (a) providing a contaminated recyclable material; (b) treating the contaminated recyclable material at a temperature in the range of from 45-30° C. with a solution that contains one or more polyols to remove contaminants from the contaminated recyclable material, wherein the one or more polyols is (are) present in an amount of at least 15 wt. %, based on the total weight of the solution, thereby forming a liquid 10 mixture which comprises one or more polyols, contaminants removed from the recyclable material, and treated recyclable material; (c) separating at a temperature in the range 10-55° C. at least part of the recyclable material as obtained in step (b) from the liquid mixture as obtained in step (b); (d) allowing at least part of the remaining liquid mixture as obtained in step (c) to phase-1 separate into a polyol phase and a phase which contains contaminants removed from the contaminated recyclable material; (e) recovering the polyol phase as obtained in step (d); (f) recovering the phase which contains contaminants removed from the recyclable material as obtained in step (d); and 20 (g) recovering the separated recyclable material as obtained in step (c).

Claims

1.-15. (canceled)

16. A non-corrosive process for cleaning a recyclable material comprising the following steps: (a) providing a contaminated recyclable material; (b) treating the contaminated recyclable material at a temperature in the range of from 45-130° C. with a non-corrosive solution that contains one or more polyols to remove contaminants from the contaminated recyclable material, wherein the one or more polyols is (are) present in an amount of at least 15 wt. %, based on the total weight of the non-corrosive solution, thereby forming a liquid mixture which comprises one or more polyols, contaminants removed from the recyclable material, and treated recyclable material; (c) separating at a temperature in the range 10-55° C. at least part of the recyclable material as obtained in step (b) from the liquid mixture as obtained in step (b); (d) allowing at least part of the remaining liquid mixture as obtained in step (c) to phase-separate into a polyol phase and a phase which contains contaminants removed from the contaminated recyclable material; (e) recovering the polyol phase as obtained in step (d); (f) recovering the phase which contains contaminants removed from the recyclable material as obtained in step (d); and (g) recovering the separated recyclable material as obtained in step (c).

17. The process according to claim 16, wherein at least part of the polyol phase as recovered in step (e) is recycled to step (b).

18. The process according claim 16, wherein the recyclable material is a recyclable clay material.

19. The process according to claim 16, wherein the recyclable material is a recyclable plastic material.

20. The process according to claim 16, wherein step (b) the solution has a pH value of 7.

21. The process according to claim 16, wherein after step (g) a step (h) is carried out in which at least part of the recyclable clay material as recovered in step (g) is subjected to a thermal treatment which is carried out at a temperature in the range of from 300-950° C.

22. The process according to claim 16, wherein in step (b) the recyclable material is treated with one or more non-corrosive solutions, wherein at least one of the non-corrosive solutions contains one or more polyols to remove contaminants from the contaminated recyclable material.

23. The process according to claim 16, wherein in step (b) the solution is a pure polyol solution that consists of one or more polyols.

24. The process according to claim 16, wherein in step (b) the solution is an aqueous solution that contains one or more water soluble polyols.

25. The process according to claim 24, wherein in the aqueous solution the one or more water soluble polyols are present in an amount in the range of from 60-99.5 wt. %, based on total weight of the aqueous solution.

26. The process according to claim 16, wherein in step (b) the weight ratio of the solution that contains one or more polyols (A) to the contaminated recyclable material (B) is in the range of from 1-3 (A/B).

27. The process according to claim 16, wherein the one or more polyols are selected from the group consisting of: meso-erythritol, pentaerythritol, xylitol, sorbitol, and glycerol.

28. The process according to claim 27, wherein at least one of the polyols is xylitol or glycerol.

29. The process according to claim 27, wherein the at least one of the polyols is glycerol.

30. The process according to claim 16, wherein in step (b) the recyclable material is contacted with a single non-corrosive solution in a single step.

Description

[0058] FIG. 1 depicts schematically a process according to the present invention.

[0059] In FIG. 1, a stream of contaminated plastic flakes or contaminated clay particles is passed via a line 1 to a cleaning vessel 2 which is operated at ambient temperature and atmospheric pressure. In cleaning vessel 2, a pure polyol solution or an aqueous solution containing one or more water soluble polyols is introduced into vessel 2 by means of line 7. In cleaning vessel 2 the stream of contaminated plastic flakes or contaminated clay particles is contacted under stirring with the pure polyol solution or the aqueous solution to remove contaminants from the plastic flakes or clay particles, thereby forming a liquid mixture of polyol, contaminants and plastic flakes or clay particles. After a predetermined period of time the plastic flakes or clay particles are separated from the liquid mixture for instance by separating means which are not shown in FIG. 1, and the plastic flakes or clay particles from which contaminants have been removed are withdrawn from vessel 2 via a line 4. The liquid mixture which contains contaminants and polyol removed from the plastic flakes or clay particles and which is separated from the plastic flakes or clay particles is withdrawn from vessel 2 via a line 3 and is then introduced in separation vessel 5. In separation vessel 5 the liquid mixture is allowed to phase-separate into a heavier polyol phase liquid (PPL) and a lighter contaminants phase liquid (CPL). At least part of the polyol phase liquid is recycled to cleaning vessel 2 via a line 6, whereas the contaminants phase liquid is withdrawn from separation vessel 5 via a line 8.

EXAMPLES

Example 1 (According to the Invention)

[0060] 50 g of spent bleaching clay which contained 46% by weight of a mixture of vegetable oils containing palm oil as the major component was mixed with 25 g of glycerol having a pH value of 7 without any corrosive compounds in a 250 ml glass flask. 25 g of water was then added. In this way a liquid mixture was obtained. After mixing for 60 minutes while heating, a temperature of 65° C. was reached. Using a cotton filter cloth in a funnel, the solid fraction of the spent bleaching clay was separated from the liquid phase. After filtering, the remaining liquid mixture was collected and left to phase-separate for 960 minutes (overnight). In this way two phases were obtained: a top layer (smallest amount, clear layer) and a bottom layer (dark layer, higher viscosity). Both phases were analyzed using IR spectroscopy (Perkin-Elmer Frontier IR spectrometer equipped with a U-ATR accessory). The filter cake was collected too and analyzed using thermogravimetric analysis (Perkin-Elmer TGA4000 equipment, in nitrogen atmosphere).

Example 2 (Comparative Example)

[0061] This example was carried out in the same manner as Example 1, except that 20 g of spent bleaching clay was used, 100 g of water was used, and no glycerol was used.

Examples 3 (Comparative Example)

[0062] This example was carried out in the same manner as Example 2, except that 0.5 g of soda was added to the liquid mixture.

Example 4 (Comparative Example)

[0063] This example was carried out in the same manner as Example 2, except that the spent bleaching clay contained 41% by weight of the oil.

Example 5 (Comparative Example)

[0064] This example was carried out in the same manner as Example 3, except that the spent bleaching clay contained 41% by weight of the oil.

Example 6 (According to the Invention)

[0065] 30 kg of glycerol having a pH value of 7 and without any corrosive compounds was preheated to 70° C. in a RVS pan. Then 30 kg of spent bleaching clay which contained 40% by weight of a mixture of vegetable oils containing palm oil as the main component was mixed with the 30 kg of preheated glycerol. After mixing for 15 minutes, a temperature of 55° C. was reached. Using a membrane pump, the mixture was pumped to a membrane-chamber filter press, equipped with a 2 micron polypropylene filter cloth. After filtering, the liquid was collected and left to phase-separate for 960 minutes (overnight). In this way to phases were obtained: a top layer (smallest amount, clear layer) and a bottom layer (dark layer, higher viscosity). Both phases were analyzed using IR spectroscopy (Perkin-Elmer Frontier IR spectrometer equipped with a U-ATR accessory). The filter cake was collected too and analyzed using thermogravimetric analysis (Perkin-Elmer TGA4000 equipment, in nitrogen atmosphere).

Example 7 (According to the Invention)

[0066] This example was carried out in the same manner as Example 6, except that the spent bleaching clay contained 45% by weight of the oil.

Example 8 (According to the Invention)

[0067] This example was carried out in the same manner as Example 6, except that the spent bleaching clay contained 46% by weight of the oil.

[0068] In Table 1, the results are shown of the IR spectroscopy analyses and the thermogravimetric analyses.

Example 9 (According to the Invention)

[0069] 30 kg of glycerol was preheated to 70° C. in a RVS pan. Then 30 kg of spent bleaching clay which contained 40% by weight of a mixture of vegetable oils containing palm oil as the main component was mixed with the 30 kg of preheated glycerol. After mixing for 15 minutes, a temperature of 55° C. was reached. Using a membrane pump, the mixture was pumped to a membrane-chamber filter press, equipped with a 2 micron polypropylene filter cloth. After filtering, the liquid was collected and left to phase-separate for 960 minutes (overnight). In this way two phases were obtained: a top layer (smallest amount, clear layer) and a bottom layer (dark layer, higher viscosity). Both phases were analyzed using IR spectroscopy (Perkin-Elmer Frontier IR spectrometer equipped with a U-ATR accessory). The filter cake was collected too and analyzed using thermogravimetric analysis (Perkin-Elmer TGA4000 equipment, in nitrogen atmosphere).

[0070] The filter cake so obtained was pressed into 6 mm pellets and fed to a 0.5 kW furnace, which was operated at 850° C. In this furnace, a heat exchanger is used to collect the heat from the furnace and use it to deliver hot water. While feeding the pellets during 30 minutes, the temperature remained constant, indicating that the calorific value of the fed material, i.e. the amount of residual organic material on the clay, was sufficient to keep the temperature at its setting point, while delivering hot water and ashes as products. The ashes were collected and analysed: the residual organic content was found to be below 2%.

Example 10 (Comparative Example)

[0071] Polypropylene (PP) sheets (thickness 500 micron) were cut into 10 mm×10 mm flakes. 6 grams PP flakes were placed in a 70 mL glass jar. 1 g of fresh frying oil (AH Frituurolie from Albert Heijn supermarket) was added and thoroughly mixed to make sure the entire plastic surface was covered with a layer of fat. In a separate jar, 40 g water and 10 h glycerol (99%, supplied by ABCR GmbH) were mixed. The combined liquids had a pH value of 7 and were held at 20° C., and added to the greasy plastics and shaken gently for 1 minute. After shaking, the liquids were filtered off and the PP flakes were rinsed thoroughly with water having a temperature of 20° C. The wet PP flakes were dried in an oven for 4 hours at 110° C. After drying, the mass of the flakes was determined. The mass before washing (PP and fat) and the total mass after cleaning were used to calculate the remaining amount of oil on the plastic surface and the cleaning efficiency. The equations below were used to calculate these quantities.

[00001]$\mathrm{Remaining}\mathrm{amount}\mathrm{of}\mathrm{oil}=\frac{\mathrm{Mass}\mathrm{remaining}\mathrm{oil}}{\mathrm{Mass}\mathrm{PP}}\times 100\%=\frac{\mathrm{Mass}\mathrm{after}\mathrm{wash}-\mathrm{Mass}\mathrm{PP}}{\mathrm{Mass}\mathrm{PP}}\times 100\%$$\mathrm{Cleaning}\mathrm{efficiency}=\left(1-\frac{\mathrm{Mass}\mathrm{remaining}\mathrm{oil}}{\mathrm{Mass}\mathrm{added}\mathrm{oil}}\right)\times 100\%=\left(1-\frac{\mathrm{Mass}\mathrm{after}\mathrm{washing}-\mathrm{Mass}\mathrm{PP}}{\mathrm{Mass}\mathrm{added}\mathrm{oil}}\right)\times 100\%$

[0072] The cleaning efficiency i.e. the relative amount of oil that was removed in this washing step, was 53%.

Example 11 (According to the Invention)

[0073] This example was carried out in the same manner as Example 10, except that the mixture of water and glycerol was heated to 50° C.

[0074] The cleaning efficiency i.e. the relative amount of oil that was removed in this washing step, was 85%.

Example 12 (Comparative Example)

[0075] This example was carried out in the same manner as Example 11, except that only water was used in the washing step, no glycerol.

[0076] The cleaning efficiency i.e. the relative amount of oil that was removed in this washing step, was 48%.

[0077] The cleaning efficiency results of Examples 10-12 are shown in Table 2.

TABLE-US-00001 TABLE 1 TGA (oil TGA (oil TGA amount amount (glycerol before after amount after IR Example cleaning, cleaning, cleaning, IR bottom No. wt %) wt %) wt %) top phase phase Example 1 46 26 20 triglycerides glycerol Example 2 46 44 0 no layer water Example 3 46 45 0 no layer water Example 4 41 40 0 no layer water Example 5 41 39 0 no layer water Example 6 40 16 40 triglycerides glycerol Example 7 45 20 26 triglycerides glycerol Example 8 46 22 33 triglycerides glycerol

[0078] From Table 1 it is clear that in accordance with the present invention attractive amounts of oil can be recovered from spent bleaching clays using relative low temperatures and an non-corrosive solutions that contains a polyol.

TABLE-US-00002 TABLE 2 Oil amount before Oil amount after Cleaning efficiency Example No. cleaning (wt. %) cleaning (wt. %) (%) Example 10 17 8 53 Example 11 18 3 85 Example 12 17 8 53

[0079] Table 2 shows that recyclable plastic material can be efficiently be cleaned using non-corrosive solutions that contain a polyol at a low temperature.