PL242683B1 - Method of processing waste multi-layer tetrapak composites using a binary solvent system - Google Patents

Abstract

The subject of the application is a method of processing waste multilayer composites of the tetrapak type, containing a paper, aluminum and polyethylene layer, in which the fragmented tetrapak composite is subjected to the action of a binary solvent system selected from the group: cyclohexane / isoamyl acetate, toluene / isoamyl acetate or xylene / isoamyl acetate, wherein the molar ratio of cyclohexane, toluene or xylene to isoamyl acetate is 0.5:0.5 to 0.6:0.4, at a temperature of 80 to 100°C, then paper solids are separated and aluminum foil from the organic liquid phase, from which polyethylene is separated by distilling off the binary solvent system.

Description

The subject of the invention is a new method of processing waste tetrapak composites.

Tetrapak packaging is characterized by low weight, airtightness and resistance to deformation. They do not let light through and give the possibility of storing products outside cold rooms for a long period.

In recent years, the packaging industry has developed and the resulting increase in the amount of waste produced. In the case of multi-component tetrapak waste, recycling is particularly difficult and results from the specificity of this type of waste. Tetrapak packaging consists of permanently connected layers of paper (approx. 75%), low-density polyethylene (LDPE) (approx. 20%) and aluminum (approx. 5%), the separation and recovery of which poses many difficulties. However, the introduced legal regulations result in the systematic development of infrastructure related to the recycling of these packaging.

The recycling process of tetrapak packaging in the industry mainly uses methods such as cellulose recovery in paper mills, recycling using organic solvents, energy recovery (incineration) and thermal decomposition by thermolysis.

In Poland, high-quality cellulose fiber is recovered from tatrapak waste packaging. Cellulose recovery in paper mills from tetrapak waste consists in the initial fragmentation of waste in a hydropulper with water. As a result, a defibrated cellulose pulp is formed, which is separated from the polyethylene-aluminium foil (so-called PolyAl). PolyAl material is used in the industry for the production of, for example, plastic products, roof tiles, garden furniture, boxes, pallets or fences, and can also be a source of alternative fuel used in the combustion process with energy recovery. The pulp is transferred to paper machines and processed.

The main difficulty in the tetrapak type waste recycling technology is - after separating the paper (cellulose) - the recovery of aluminum and polyethylene. The procedure is as follows: after separation of paper pulp, a solvent (mixture of solvents) is introduced into the system at a specific temperature and time, then the LDPE solution is filtered off, and then the solvent is distilled off and recycled to obtain pure LDPE.

Two methods of separating aluminum from polyethylene after paper removal are known from the literature: 1) the "wet" method (using solvents) described, for example, in the publications of D. Yan, Z. Peng, Y. Liu, L.Li, Q. Huang, M. Xie, Q. Wang, Optimizing and developing a continuous separation system for the wet process separation of aluminum and polyethylene in aseptic composite packingwaste, Waste management, 2015, 35, 21; D.S. Achillas, C. Roupakias, P. Megalokonomos, A. A. Lappas, E.V. Antonakou, Chemical recycling of plastic waste made from polyethylene (LDPE and HDPE) and polypropylene (DP), Journal of Hazardous Materials 2007, 149, 536; G.J. Cao, Aluminum-plastic separation reagent and method, 2009, Chinese Patent ZL200710132936.X (in Chinese); S.F. Zhang, L.L. Zhang, X.X. Mei, Research on aluminum-plastic separation process with benzyl-alcohol-water method, China Pulp. Paper, 2011, 32, 43, and 2) the "dry" method described e.g. in G. Parkinson, Plasma recycling process debuts, Chem. Eng. Threshold. 2005, 101-13, and the literature US 6,401,635 B1, US 5,421,526(A). For example, D. Yan, Z. Peng, Y. Liu, L.Li, Q. Huang, M. Xie, Q. Wang, Optimizing and developing a continuous separation system for the wet process separation of aluminum and polyethylene in aseptic composite packingwaste. Waste management, 2015, 35, 21, acids (HCl, HCOOH, CH3COOH) were used to separate aluminum from LDPE foil, dissolve aluminum oxide and penetrate polyethylene foil, the process being carried out at a temperature of 30-80°C, at pH = 1. As a result of this method, 98% of polyethylene and 72% of aluminum were recovered.

Another method of processing multi-layer tetrapak waste is burning it as a component of RDF fuels and partial recovery of thermal energy. Currently, such multi-component materials are also subjected to the thermolysis process. The process is carried out at high temperature, from 320 to 460°C, without access to air, with naturally increasing pressure. A mixture of hydrocarbons (liquid fractions, combustible gases) and a solid fraction (char, metal scrap, mineral impurities) are obtained.

All existing methods have significant limitations and disadvantages that require new solutions.

The subject of the invention is a new method of processing waste multilayer tetrapak composites using a binary solvent system.

In the process of the invention, multilayer tetrapak composites are treated with two solvents exhibiting a positive synergistic effect. The synergistic effect of the binary solvent system allows to reduce the cost of the process and increase its efficiency by shortening the time and lowering the temperature needed to separate the components of tetrapak composites. As a result of the process, separated paper flakes are obtained (without the effect of defiberation), aluminum, and polyethylene (PE) is dissolved. Polyethylene is separated by distilling off solvents that can be reused in the next process cycle. Parts of the tetrapack, such as the threaded nut, remain unchanged.

The method of processing waste multi-layer composites of the tetrapak type, containing a paper, aluminum and polyethylene layer, according to the invention consists in the fact that the tetrapak composite fragmented to particles with a size of preferably up to 100 mm ² is subjected to the action of a binary compress of solvents selected from the group: cyclohexane / isoamyl acetate , toluene / isoamyl acetate or xylene / isoamyl acetate, in which the molar ratio of cyclohexane, toluene or xylene to isoamyl acetate is 0.5 : 0.5 to 0.6 : 0.4, at a temperature of 80 to 100 °C and during from 0.5 to 3 hours, then the paper and aluminum foil solids are separated from the organic liquid phase, from which the polyethylene is separated by distilling off the binary solvent system.

In the method according to the invention, a tetrapak composite is used, crushed preferably to particles with a size of 50 mm ² to 100 mm ² .

According to the invention, the tetrapak composite is treated with a binary solvent system preferably for 1 hour.

Preferably, the process according to the invention is carried out at a temperature of 80°C.

Preferably, the method of the invention is carried out at a tetrapak to binary solvent weight ratio of 1:10 to 1:33, most preferably at a weight ratio of 1:10.

The separated flakes of aluminum and paper after filtration from the organic liquid phase containing polyethylene are in a mixed state. They can be separated using, for example, an electrostatic divider (separator).

It has been found that a positive synergistic solubility effect in the process of the invention can be obtained using a molar ratio of Solvent 1 (isoamyl acetate) to Solvent 2 (cyclohexane, toluene, xylene) as 0.5 : 0.5 and 0.4 : 0.6 ( Table 1-5). It turned out that the synergistic effect of the solvents used allowed to reduce the temperature needed to achieve full separation of the components up to 80°C and reduce the time of the process to 1 hour.

The subject of the invention is illustrated in the examples of execution for different temperatures and times of the process, with a variable composition of the binary solvent.

Examples 1-9

Separation of the tetrapak composite components using a binary solvent system in which the molar ratio of Solvent 1 to Solvent 2 was 0.5:0.5.

The separation of the main components of the crushed (50 mm ² to 100 mm ² ) tetrapak material was carried out using a mixture of two solvents: 1 (isoamyl acetate) and 2 (cyclohexane, toluene or xylene), at the temperature of 100°C and for 3 hours or 1 hour, be at 80°C for 1 hour. Solvents were used in equimolar amounts (1:1).

In a 150 ml flask equipped with a magnetic stirrer, a reflux condenser and a thermometer, samples of the tested material and a mixture of solvents were placed and heated. The paper and aluminum flakes were then separated by filtration. The filtrate was concentrated by distilling off the solvents at a temperature of 40-55°C and a reduced pressure of 12-40 hPa. After completion of the distillation, the obtained residue was dried at 50°C and 2 hPa pressure, and then the precipitated PE precipitate was weighed.

PL 242683 B1

Table 1. Binary solvent separation of components at 100°C for 3 hours.

Example Solvent 1 Solvent 2 start 1+2 (g) Mass samples (g) Al weight (g) paper weight te) Mass EP(g) 1 isoamyl acetate 0.25 mol 32.552/ 37.16 g/ml cyclohexane 0.25 mol 21.045/27.02 g/ml 53,597 1.607 0.105 1.047 0.354 2 isoamyl acetate 0.25 mol 32.552/ 37.16 g/ml toluene 0.25 mol 23.036/ 26.72 g/ml 55.588 1.601 0.118 1,140 0.333 3 isoamyl acetate 0.23 mol 29.946/ 34.19 g/ml xylene 0.23 mol 24.418/28.20 g/ml 54.364 1,560 0.103 1,097 0.340

NOTE: For the system of Example 1, the separation of components took place already at the temperature of 89~90°C.

Table 2. Separation of components using a binary solvent at 100°C for 1 hour.

Example Solvent 1 Solvent 2 start 1+2 (g) Mass samples (g) Mass Al (g) Paper weight (g) Mass EP(g) 4 isoamyl acetate 0.25 mol 32,552/ 37.16 g/ml cyclohexane 0.25 mol 21.045/27.02 g/ml 53,597 1.604 0.108 1.119 0.337 5 isoamyl acetate 0.25 mol 32.552/ 37.16 g/ml toluene 0.25 mol 23.036/ 26.72 g/ml 55.588 1,597 0.106 1.095 0.344 6 isoamyl acetate 0.23 mol 29,946/ 34.19 g/ml xylene 0.23 mol 24,418/ 28.20 g/ml 54,364 1.600 0.090 1.211 0.285

NOTE: For the system of Example 4, the separation of components took place already at the temperature of 89-90°C.

Table 3. Binary solvent separation of components at 80°C for 1 hour.

Example Solvent 1 Solvent 2 start 1+2 (g) Mass samples (g) Al weight (g) Paper weight (g) PE weight (g) 7 isoamyl acetate 0.25 mol 32,552/ 37.16 g/ml cyclohexane 0.25 mol 21.045/27.02 g/ml 53,597 1.604 0.101 1.188 0.318 8 isoamyl acetate 0.25 mol 32.552/ 37.16 g/ml toluene 0.25 mol 23.036/ 26.72 g/ml 55.588 1,598 0.093 1.191 0.310 9 isoamyl acetate 0.23 mol 29.946/ 34.19 g/ml xylene 0.23 mol 24.418/28.20 g/ml 54.364 1.553 0.092 1.152 0.310

The unglued aluminum and paper flakes, after being filtered from the organic liquid phase containing polyethylene, can be separated using, for example, an electrostatic separator (separator).

PL 242683 B1

Example 10-17

Separation of the tetrapak composite components using a binary solvent system in which the molar ratio of Solvent 1 to Solvent 2 was 0.4:0.6.

The separation of the main components of the crushed (50 mm ² to 100 mm ² ) tetrapak material was carried out using a mixture of two solvents: 1 (isoamyl acetate) and 2 (cyclohexane, toluene or xylene), at the temperature of 80°C and for 1 hour. Solvents were used in amounts corresponding to a molar ratio of Solvent 1 to Solvent 2 of 0.4:0.6 (2:3).

In a 150 ml flask equipped with a magnetic stirrer, a reflux condenser and a thermometer, samples of the tested material and a mixture of solvents were placed and heated. The paper and aluminum flakes were then separated by filtration. The filtrate was concentrated and the precipitated PE was weighed. Table 4. Binary solvent separation of components at 80°C for 1 hour.

Example Solvent 1 Solvent 2 start 1.+2 (g) Mass samples (?) Mass all) Paper weight (g) PE weight (g) 10 acetate isoamyl 0.2 mol 26.040/ 29.73 g/ml cyclohexane 0.3 mol 25.254/32.42 g/ml 51.294 1.564 0.092 1.168 0.302 11 isoamyl acetate 0.2 mol 26.042/ 29.73 g/ml toluene 0.3 mol 27,648/ 32.07 g/ml. 53,690 1,550 0.092 1.146 0.300 12 isoamyl acetate 0.19 mol 24,738/ 28.24 xylene 0.285 mol 30,258/ 34.94 54,996 1.592 0.091 1.202 0.316 13 () isoamyl acetate 0.19 mol 24,745/ 28.25 gsm! xylene 0.285 mol 30.261/ 34.94 g/ml 55.006 3.004 0.177 2,199 0.605 14 ABOUT acetate isoamyl 0.19 mol 24.745/28.25 g/ml xylene 0.285 mol 30.261/ 34.94 g/ml 55.006 5,000 0.303 3,660 0.951 1S () isoamyl acetate 0.2 mol 26.040/ 29.73 cyclohexane 0.3 mol 25.254/ 32.42 51.294 3.014 0.192 2.232 0.590 16 (“) isoamyl acetate 0.2 mol 26.040/ 29.7 g/ml cyclohexane 0.3 mol 25,254/ 32.42 g/ml 51.294 5.021 0.354 3,680 0.982

( ) In the experiment, the amount of tetrapak material was increased to 3.0 g.

(**) The amount of tetrapak material was increased to 5.0 g in the experiment.

Table 5. Binary solvent separation of components at 80°C for 0.5 hour.

Example Solvent 1 Solvent 2 start 1+2 (g) Mass these samples) Al weight (g) paper weight te) PE weight (g) 17 c) isoamyl acetate 0.2 mol 26.040/ 29.73 g/ml cyclohexane 0.3 mol 25.254/32.42 g/ml 51.294 3.006 0.194 2.228 0.589

Based on literature data and conducted experiments, it can be concluded that the processing of tetrapak material with pure hydrocarbons is a long-term and energy-intensive process. Full separation of the layers is obtained after 6 hours in cyclohexane at a temperature of about 80°C, after 9 hours in toluene at 100°C, after 6 hours in xylene at 100°C. The method according to the invention allows to shorten the time and lower the temperature needed to separate the layers of the tetrapak material. The use of a binary solvent allows the process to be carried out at a temperature not exceeding 90°C and shortening the time of its execution to 1 hour, which leads to significant energy savings. In addition, the analysis of the results from the Table shows that the use of a binary solvent system: 1 (isoamyl acetate) and 2 (cyclohexane, toluene, xylene) in a molar ratio of 0.4 : 0.6, compared to the 0.5 : 0 system, 5, allows to increase the amount of tetrapak material subjected to the method according to the invention to 5 g, which is 10% of the solvent mass (for the 0.5:0.5 system, this ratio was about 3% of the solvent mass).

Claims (5)

1. A method of processing waste multilayer composites of the tetrapak type, containing a paper, aluminum and polyethylene layer, characterized in that the tetrapak composite fragmented to particles with a size of preferably up to 100 mm ² is subjected to the action of a binary solvent system selected from the group: cyclohexane / isoamyl acetate, toluene / isoamyl acetate or xylene / isoamyl acetate, in which the molar ratio of cyclohexane, toluene or xylene to isoamyl acetate is 0.5 : 0.5 to 0.6 : 0.4, at a temperature of 80 to 100 °C and from 0.5 to 3 hours, then the paper and aluminum foil solids are separated from the organic liquid phase, from which the polyethylene is separated by distilling off the binary solvent system. 2. The method of claim A method according to claim 1, characterized in that the tetrapak composite is comminuted to a particle size of 50 mm ² to 100 mm ² . 3. The method of claim The method of claim 1, wherein the tetrapak composite is exposed to the binary solvent system for 1 hour. 4. The method of claim The method according to claim 1, characterized in that it is carried out at a temperature of 80°C. 5. The method of claim The process of claim 1, wherein the tetrapak to binary solvent composite weight ratio is 1:10 to 1:33, most preferably 1:10 weight ratio.