WO1998047681A1

WO1998047681A1 - Process for the recovery of aluminium, cellulose and polyethylene from pack type package residues and wastes

Info

Publication number: WO1998047681A1
Application number: PCT/ES1998/000093
Authority: WO
Inventors: Diego Cortes Vargas
Original assignee: Diego Cortes Vargas
Priority date: 1997-04-17
Filing date: 1998-04-15
Publication date: 1998-10-29
Also published as: ES2124189A1; ES2124189B1

Abstract

The process comprises: a) dry separation of the material forming the package into two layers: (i) a first layer (A) which comprises the natural cellulose layer (4), the processed cellulose layer (5) and a sheet of polyethylene (6); and (ii) a second layer (B) which comprises the remainder of the polyethylene sheets (2, 3) and the aluminium sheet (1); b) immersing said first layer (A) into water and separating the cellulose layer (4, 5) from the polyethylene sheets (6); c) immersing said second layer (B) into a solution which is appropriate for the separation of the aluminium sheet (1) from the polyethylene sheets (2, 3), without attacking the aluminium nor the polyethelne; and (d) separating the aluminium sheet (1) from the polyethylene sheets (2, 3). Said process provides for a complete recycling of materials of interest contained in process residues and waste materials.

Description

METHOD FOR RECOVERY OF ALUMINUM, CELLULOSE AND POLYETHYLENE FROM WASTE OF PACK TYPE CONTAINERS

FIELD OF THE INVENTION This invention relates to a method for the integral recovery of aluminum, cellulose and polyethylene from packaging waste:

BACKGROUND OF THE INVENTION One of the most common ways of packaging products, in particular food products, includes the use of pack-type packages :. This type of packaging is made from a material composed of sheets of cellulosic materials, aluminum and polymers, generally low density polyethylene. This material, due to its hygiene and impermeability characteristics, is very suitable for manufacturing containers intended to contain food products.

These containers are manufactured in very high quantities, so a large amount of waste is generated that must be treated properly. The usual treatments for this type of waste include its storage in controlled landfills or its use as fuel due to its calorific value. None of these treatments provide a definitive solution to the problem caused by these wastes or a use of the valuable materials (aluminum, cellulose and polyethylene) contained in such wastes.

Different methods have been developed to try to recover and take advantage of all or some of these materials. Thus, a method is known for recovering the cellulosic material contained in pack-type packaging waste: comprising the treatment of said waste with hot water, whereby the carton of the package is softened and a mixture of cellulose fibers is obtained which They can be separated from the water bath, recovered and reused. A common method of recovering aluminum comprises the thermal treatment of the waste, although this method causes the decomposition of the polymeric material and the generation of gases that must be treated or recycled for combustion. European Patent EP 543302 describes a method for separating aluminum sheets from polyethylene sheets comprising heating the sheet composed of aluminum and polyethylene sheets, with acetic acid at a concentration of at least 20%, at a temperature between 100 and 122 ° C, cool the mixture to sub-atmospheric pressure and separate the aluminum sheets from the polyethylene ones. This method requires the use of concentrated acetic acid and heat input, which reduces the overall economic balance of the process.

Spanish patent application No. P9302228 describes a process for the recovery of polyethylene and aluminum comprising hot extraction of polyethylene and hot separation of aluminum. This procedure uses organic solvents, which requires its elimination or recovery, as well as a contribution of heat, all of which reduces the economic balance of the process. As can be seen, none of the known methods provides a recovery of all the materials of interest contained in the packaging waste packaging. Therefore, an objective of the present invention is to provide an effective method for the integral recovery of aluminum, polyethylene and cellulosic material contained in packaging waste packaging. The recovery of these valuable materials improves the economic balance of the process.

On the other hand, the known methods for recovering aluminum and polyethylene from this type of waste suffer from a series of drawbacks (decomposition of polymeric material, gas generation, energy consumption, use of organic solvents). Therefore, a second objective of this invention is a method for the recovery of aluminum and polyethylene from pack-type packaging waste. that overcome the above mentioned inconveniences.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a cross section of a characteristic material used in the manufacture of pack-type containers, where the different constituent layers and materials are shown, enlarged.

DETAILED DESCRIPTION OF THE INVENTION The invention provides a method for the integral recovery of aluminum, cellulose and polyethylene from pack-type packaging waste comprising the steps of: a) dry separating the constituent material of the package in two layers , a first layer comprising the cellulosic material and a polyethylene sheet, and a second layer comprising the rest of the polyethylene sheets and the aluminum sheet; b) immersing said first layer in water and separating the cellulosic material from the polyethylene sheet; c) immersing said second layer in a solution suitable for separating the aluminum foil from the polyethylene sheets and which does not attack either the aluminum or the polyethylene; and d) separating the aluminum sheet from the polyethylene sheets.

The method is suitable for the treatment of pack packaging waste. This type of packaging is made from a material comprising a composite sheet formed by an aluminum sheet surrounded by one or two sheets of polyethylene, a cellulosic material and an additional sheet of polyethylene on the surface of the cellulosic material. The cellulosic material comprises, in general, two different types of cellulose, one that exerts a structural function, formed by natural cellulose or cardboard, hereinafter "natural cellulose" and a second type intended to contain information on the packaged product, formed by a discolored cellulose, hereinafter "treated cellulose".

The waste to be treated, before being subjected to the method of the invention, can optionally be washed with water, in order to remove most of the impurities outside the residue.

For the realization of the method of this invention, the residues of the packages to be treated are cut by the ends and / or by the sides in order to open the container in its entire length or in smaller fragments.

The separation of the constituent material of the package into two layers is carried out dry, pulling and exfoliating for example, by one of the ends, corners or sides of the sheet of the material to be treated, whereby a first layer comprising the material is separated cellulosic and the outer coating polyethylene sheet, and a second layer comprising the rest of the polyethylene sheets and the aluminum sheet.

The first layer is immersed in water, at a temperature between 5 and 30 ° C, and at atmospheric pressure, for a period of time between 6 and 24 hours, thereby separating the cellulosic material from the polyethylene sheet. Through this treatment, the cellulosic material is separated into two fractions, one corresponding to the structural cellulose that separates with a texture and appearance of the structural material, and another fraction corresponding to the treated cellulose that separates with the typical appearance of the washed paper . The separated polyethylene sheet contains a small part of the treated cellulose fraction adhered on the surface of the polyethylene, usually less than 2% by weight with respect to the total initial treated cellulose. This treated cellulose adhered to the polyethylene can be separated by washing, blowing or erosion with a slightly abrasive medium so as not to damage the polyethylene. Although it is not desired to be bound by any theory it is believed that the separation between cellulosic material and polyethylene occurs due to a hydration of the cellulosic material that thereby loses its ability to adhere to polyethylene.

The second layer is immersed in a solution suitable for separating aluminum from polyethylene sheets that does not attack either aluminum or polyethylene. An example of such a solution is an aqueous solution of acetic acid, with a concentration between 3 and 15% by weight. Immersion of the second layer in said solution is carried out at a temperature between 5 and 30 ° C, at atmospheric pressure, and for a period of time between 1 and 5 days, depending on the concentration of the acetic acid solution used . Through this treatment, the aluminum foil can be easily separated from the polyethylene sheets by simple exfoliation. Although it is not desired to be bound by any theory, it is believed that acetic acid causes solubilization of the binder between the aluminum sheet and the polyethylene sheets, thereby separating said sheets.

The invention will be described in more detail below, with reference to the Figure accompanying this description.

Figure 1 shows a cross section of a characteristic material used in the manufacture of pack-type containers comprising an aluminum foil (1) surrounded by two sheets of polyethylene (2) and (3) that can be the same or different . In contact with the polyethylene sheet (3) is a layer of natural cellulose (4), which exerts a structural function, and a layer of a treated cellulose (5), for example, discolored by treatment with calcium hypochlorite, intended for Contain the information on the packaged product. Layers (4) and (5) constitute the layer of cellulosic material. Finally, the material contains a polyethylene sheet (6), which can be the same or different from the polyethylene sheets (2) and (3). The method to recover aluminum, cellulose and polyethylene From pack type packaging waste formed with a material such as that shown in Figure 1, it comprises: a) dry separating the constituent material from the package in two layers: - a first layer (A) comprising the layer of natural cellulose (4), the treated cellulose layer (5), that is, the cellulosic material, and a polyethylene sheet (6), and

- a second layer (B) comprising the rest of the polyethylene sheets (2) and (3) and the aluminum sheet (1); b) immerse said first layer (A) in water and separate the cellulose layers (4) and (5) from the polyethylene sheet (6); c) immersing said second layer (B) in a solution suitable for separating the aluminum sheet (1) from the polyethylene sheets (2) and (3) and not attacking either the aluminum or the polyethylene; and d) separating the aluminum sheet (1) from the polyethylene sheets (2) and (3).

The residues of the containers to be treated are subjected to a previous wash with water, if desired, and subsequently, they are cut by the ends and / or by the sides in order to open the container in its entire length or in smaller fragments .

The separation of the constituent material of the container into two layers is carried out dry, pulling and exfoliating at one of the ends, corners or sides of the sheet of the material to be treated, thereby separating a first layer (A) comprising the material cellulosic (4) and (5) and the outer coating polyethylene sheet (6), and a second layer

(B) comprising the rest of the polyethylene sheets (2), (3) and the aluminum sheet (1).

The first layer (A) is immersed in water, at a temperature between 5 and 30 ° C, preferably at room temperature, and at atmospheric pressure, for a period of time between 6 and 24 hours, preferably 12 hours, whereby the cellulosic material is separated into two fractions, one corresponding to natural cellulose (4) and another to treated cellulose (5) that separates with the typical appearance of the washed paper. The separated polyethylene sheet (6) contains a small part of the treated cellulose fraction (5) adhered on the surface of the polyethylene (6) that can be separated by washing with water, blowing with air, or by erosion with a slightly medium abrasive, such as a sponge, a roller or a scourer, so as not to damage polyethylene. The second layer (B) is immersed in an appropriate solution such as an aqueous solution of acetic acid, with a concentration between 3 and 15% by weight. The immersion is carried out at a temperature between 5 and 30 ° C, at atmospheric pressure, and for a period of time between 1 and 5 days, depending on the concentration of the acetic acid solution used. In a particular embodiment, the concentration of acetic acid is between 4 and 10% by weight, the immersion is carried out at room temperature and lasts about 3 days. By this treatment, the aluminum sheet (1) can be easily separated from the polyethylene sheets (2) and (3) by simple exfoliation.

The recovered materials (aluminum, cellulose and polyethylene) according to the method of this invention can be recycled and reused, for example, in the manufacture of new pack-type containers.

Through the method object of this invention, an integral recovery and complete recycling of all the materials of interest contained in the treated waste is achieved. Specifically, the recovery of aluminum and polyethylene is practically quantitative as well as the recovery of natural cellulose, while the losses in treated cellulose due to the immersion of said first layer in water are of the order of 2% by weight with respect to that contained. initially in the container. The method object of this invention can be carried out continuously or discontinuously.

An additional advantage of the method object of this invention lies in the possibility of developing it in a modular way, that is, by performing only the necessary treatments to recover one or two of said materials of interest, that is, performing the treatments conducive well to recovery. of cellulosic material, or to the recovery of aluminum or polyethylene sheets. The following example serves to illustrate a particular way of performing the method of the invention and should not be considered as limiting the scope thereof.

EXAMPLE 1 Some 1-liter pack-type containers were washed with water, crushed, the ends were cut and opened by a cut on one side, so that they extended over their entire length.

Next, the washed and cut containers were subjected to a dry exfoliation process, pulling through a corner and separating the material from the package into two layers, a first layer containing the cellulosic material and the outer coating polyethylene sheet, and a second layer containing the rest of the polyethylene sheets and the aluminum sheet.

The first layer is immersed in water at room temperature (22 ° C), and atmospheric pressure, for 12 hours, which separates the polyethylene sheet from the cellulosic material consisting of two fractions, the one corresponding to natural cellulose, which it presents the characteristic color and texture of natural cellulose, and that corresponding to the treated cellulose that separates with the typical appearance of the washed paper. The separated polyethylene sheet contains about 2% by weight of the treated cellulose adhered on its surface. The second layer is immersed in an acid solution 6% acetic by weight, at room temperature (22 ° C), and atmospheric pressure for 3 days. After that time, the polyethylene sheets and the aluminum sheet can be easily separated by exfoliation. After the method, a practically quantitative recovery of aluminum, polyethylene and structural cellulose is observed, while the percentage of treated cellulose recovered was approximately 98% by weight because about 2% remained adhered to the external polyethylene sheet .

Claims

1. A method for the integral recovery of aluminum, cellulose and polyethylene from pack-type packaging waste comprising the steps of: a) dry separating the constituent material from the package in two layers, a first layer comprising the cellulosic material and a polyethylene sheet, and a second layer comprising the rest of the polyethylene sheets and the aluminum sheet; b) immersing said first layer in water and separating the cellulosic material from the polyethylene sheet; c) immersing said second layer in a solution suitable for separating the aluminum foil from the polyethylene sheets and which does not attack either the aluminum or the polyethylene; and d) separating the aluminum sheet from the polyethylene sheets.

2. A method according to claim 1, wherein said pack-type containers are made from a material comprising a composite sheet formed of an aluminum sheet surrounded by one or two sheets of polyethylene, a cellulosic material and a sheet additional polyethylene on the surface of the cellulosic material.

3. A method according to claim 2, wherein said cellulosic material comprises a natural cellulose, which exerts a structural function, and a treated cellulose, intended to contain information about the packaged product.

4. A method according to claim 1, wherein the waste to be treated is pre-washed with water before carrying out step a).

5. A method according to claim 1, wherein the waste to be treated is cut at the ends and / or the sides in order to open the container in its entire length or in smaller fragments.

6. A method according to claim 1, wherein the separation of the constituent material of the package into two layers is carried out dry, exfoliating at one of the ends, corners or sides of the package to be treated.

7. A method according to claim 1, wherein said first layer is immersed in water at a temperature between 5 and 30 ° C.

8. A method according to claim 7, wherein said first layer is immersed in water at room temperature.

9. A method according to claim 1, wherein said first layer is immersed in water at atmospheric pressure.

10. A method according to claim 1, wherein said first layer is immersed in water for a period of time between 6 and 24 hours.

11. A method according to claim 10, wherein said first layer is immersed in water for 12 hours.

12. A method according to claim 1, wherein said second layer is immersed in a solution of acetic acid with a concentration between 3 and 15% by weight.

13. A method according to claim 12, wherein said second layer is immersed in a solution of acetic acid with a concentration between 4 and 10% by weight.

14. A method according to claim 1, wherein said second layer is immersed in a solution of acetic acid at a temperature between 5 and 30 ° C.

15. A method according to claim 14, wherein said second layer is immersed in a solution of acetic acid at room temperature.

16. A method according to claim 1, wherein said second layer is immersed in an acetic acid solution at atmospheric pressure.

17. A method according to claim 1, wherein said second layer is immersed in an acetic acid solution for a period of time between 1 and 5 days.

18. A method according to claim 17, wherein said second layer is immersed in a solution of acetic acid for 3 days.