Polyethylene processing: equipment, technology. Polyethylene recycling: waste recycling technology What can be produced from PVD film waste

The production of pellets from polyethylene waste is one of the most profitable and environmentally friendly businesses. Secondary LDPE or HDPE granules make it possible to reduce the cost of production of new products without compromising their quality. Many products made from recycled materials are in no way inferior in quality to goods made from primary raw materials.

Secondary granule LDPE

What is a recycled polyethylene granule

PVD granules — it is a fine-grained bulk material consisting of spherical or cylindrical grains with a diameter of 0.2 to 0.5 mm. It is made from polyethylene high pressure(PVD). There are also granules of low-pressure polyethylene - HDPE, and some other less commonly used types of this polymeric material.

Primary polyethylene is produced from oil, the reserves of which are not endless. Therefore, the production of recycled LDPE and HDPE granules is gaining more and more economic importance every year.

The color of the granules depends on the color of the feedstock. They are mostly whitish-translucent. The recycling plant sorts recyclables by color, so green bottles and bags, for example, are recycled separately from transparent ones.

Where does recycled polyethylene come from?

Manufacturers of HDPE and LDPE pellets replenish stocks of raw materials by buying up used plastic containers - bottles of any color and volume, stretch film, etc. The company sorts raw materials by color.

Recycled low-density polyethylene is obtained primarily through the recycling of plastic bottles. The volumes of their daily discharge to landfills in large cities are huge, they amount to tens of tons, despite the lightness of raw materials. The recycling of plastic boxes, pipes and other similar waste is also used. We recycle waste non-woven covering material, shrink film, some types of construction waste, etc.

For the "secondary" production of LDPE granules, wastes of primary, synthesized high-pressure polyethylene are also used. In this case, it is only necessary to ensure that a third recycling cycle is not allowed. It is impossible to recycle polymers for the third time - the quality of the goods is deteriorating sharply.

Processing technology

Polyethylene granules are obtained from LDPE agglomerate - polyethylene crumb. The recycling process consists of the following steps:

1. Sorting. It is produced at a landfill or directly at a processing plant. Raw materials are sorted by type - bottles, bags, wire insulation, etc., by size, by degree of contamination. Too dirty raw materials are not used, or subjected to thorough washing.
2. Grinding of raw materials to such sizes that the company's machines are capable of processing - on average from 0.5 to 15 mm.
3. Washing in special washing chambers. Necessary because dirty feedstock will produce cloudy, low quality polyethylene granules. The quality of the resulting product directly depends on the quality and purity of raw materials.
4. Purging in centrifuges to remove excess moisture.
5. Pre-drying.
6. Agglomeration is a partial melt of washed and dried crumbs followed by sintering. Produced under pressure. Preliminary stage before obtaining polyethylene granulate.
7. Granulation is the processing of polyethylene into granules. On the modern enterprises produced simultaneously with agglomeration in plastic compactors. On the equipment of the previous generation, it was a separate stage of the process.

The PVD granulator is an apparatus that heats the polyethylene mass simultaneously with its last, final filtration from possible inclusions of metals and other impurities. After melting (heating the polyethylene mass to a temperature of 200 degrees Celsius), it is fed under pressure to the spinneret - a fine-meshed frame. Passing through it, the semi-liquid melt takes the form of thin sausages, which are cut with screw knives in a fraction of a second. Further, the resulting polyethylene granules are sent for cooling and packaging.

At this stage, the production of polyethylene granules ends.

What is made from the secondary granule?

Recycled polyethylene granule has found application in the manufacture of:

• packaging (secondary stretch film, technical film, plastic bags);
• bottles for non-alcoholic or low-alcohol liquids;
• disposable tableware;
• decor items;
• materials for hydro- and thermal insulation;
• water pipes (used in low pressure systems);
• polymer tiles;
• plastic garden furniture;
• any other products that, during operation, must not withstand significant physical and electrical loads. This means that insulation for electrical cables, for example, is no longer made from pure "secondary" HDPE. But in some cases it is used in the form of additives - up to 50% by weight, in order to reduce the cost of production.

Recycled LDPE is used to make fittings and pipes, car parts, hoses, non-woven material, cable insulation, roofing material and polymer tiles, housings for various machines and mechanisms,

Why recycling HDPE and LDPE is beneficial

Polyethylene recycling is one of the most profitable types of modern environmental business:

• Buying HDPE in granules is much more profitable than using virgin polyethylene. Its synthesis requires oil, the synthesis process is technologically complex. Recycled polyethylene is easier to produce, so it costs several times cheaper than primary.
• Recycled polyethylene in granules, packaged in any container (usually bags are used - "big-bags"), can be stored in a warehouse for several years. He is not afraid of high humidity or other unfavorable conditions.
• Enterprises involved in the processing of recycled polyethylene have a high percentage of profitability, since their raw material costs are minimal, technological process does not differ in complexity and does not require expensive equipment, and the demand for final products is high and constant.
• With active recycling plastic bottles, bags and other packaging materials can significantly reduce the area allocated for landfills for the disposal of used packaging, and improve the environmental situation in the city, country and world. Decomposing (the decomposition period is about 300 years), polyethylene releases harmful substances into the atmosphere. Given the volume of its production, in the future this may become a serious problem.

Polyethylene recycling is a profitable and environmentally friendly business. It allows the use of available resources for production, which significantly saves mineral reserves on the planet and reduces the cost of the resulting polymer products.

To reduce the cost and reduce the cost of manufacturing products from polymers, manufacturers are increasingly practicing the use of recycled high-density polyethylene ( LDPE granules). Recycled polyethylene recycled materials produce a first-class and very profitable granular material, which, in terms of quality characteristics, is not inferior to raw materials from virgin polyethylene. Each secondary LDPE granule has a low density and has the same branched molecular structure as before processing.

To date, the production of secondary granules from LDPE waste helps to solve a whole range of environmental problems related to the disposal of polymers, and also allows you to significantly reduce the cost of manufacturing products from LDPE polymers.

Technological cycles of processing. Applied equipment.

LDPE granules are obtained by polymerization of ethylene under high pressure (150-300 mPa). Various methods of processing LDPE waste are based on chemical mechanisms of coordination and interaction of secondary polyethylene with added modifying additives. Technologically, the technique consists of such stages as:

• Raw material collection and sorting. The secondary is distributed by brand, separated from sand, dirt, metal, adhesive tape, other foreign inclusions and debris.
• Washing and drying of waste in washing and drying complexes. When washing secondary LDPE, special reagents and chemicals can be added to the pre-cleaning unit to remove complex contaminants from raw materials (petroleum products, grease, oil). Mini-flotation and metal separation operations can be performed. Before being sent to the drying chamber, to separate excess moisture and the remaining solid fractions, the raw material is sent to a centrifuge. To avoid the formation of various kinds of defects (bloatings, shells, pores) at this stage of processing, the drying process of the polymer is carried out at high humidity;
• Grinding and crushing. For plastic materials, cutting and abrasion methods are used, fragile secondary polyethylene is pre-crushed by a cut or impact, crushed. To perform these technical processes, knife crushers (dicers), hammer and rotary types of grinders, jet mills are used;
• Direct processing of prepared LDPE, obtaining agglomerate. In the agglomerator, as a result of thermal action (friction against the body), secondary polyethylene is heated to the temperature of plasticization and sintered, after which it is rapidly cooled and divided into separate balls (pellets). Agglomerators can perform both separate stages of secondary LDPE processing, and full cycle regeneration of polymers, including all of the above steps. The resulting agglomerate can be used for the production of finished products;
• Granulation of polymers and composites. At this stage, special granulators are used, in which the molten thermoplastic polymer enters through an extruder. After the resulting material cools in water or in air, high-pressure polyethylene pressed into threads or bundles is cut into granules. During the process, the secondary can be combined with dyes, plasticizers, antioxidants, bactericidal materials, volatile impurities and water are removed from it. The secondary LDPE granule can be produced in dyed and unpainted forms.

In the process of production of recycled high-density polyethylene, attention should be paid to the density of the material; consumer characteristics of finished products depend on it. An increase in its performance leads not only to an increase in the hardness and strength of the material, resistance to aggressive environments, but at the same time makes it less impact resistant and easily permeable to gases.

Special characteristics of granules and agglomerate

The resulting secondary LDPE is characterized by:

• perfect dielectric abilities;
• lack of absorption of moisture, steam and maintaining a constant mass of granules;
• resistance to a wide variety of chemicals, as a result, storage and transportation process does not require the creation of special conditions;
• odorless and completely inert. Products made from recycled LDPE granules are distinguished by the almost complete absence of a chemical smell of plastic;
• high bulk density;
• resistance to ultra-low temperatures.

Application of secondary granules

• For casting: thin-walled and large-sized products, fittings, auto parts, bottles, consumer containers for non-food products.
• For the production of: irrigation, drip irrigation, pressure and polyethylene pipes, corrugated hoses, geomembranes, foam products, non-woven materials and threads, low-quality cable insulation films.
• For the manufacture of: roofing material, polymer-sand tiles, heat-shrinkable, greenhouse, covering, insulating films, household items, housings and components for electrical appliances and refrigerators, building materials, containers for liquid and bulk chemicals, furniture plastic.

Improving the methods of processing LDPE waste lead to the creation of completely new, versatile materials. Today, cross-linked polyethylene is in demand and in high demand. It has improved physical properties and a wide range of applications.

Thanks to modern technologies, high-quality polyethylene produced from polyethylene waste secondary LDPE, in terms of its physical and mechanical properties and purity approaches the primary product. It is also important that from the point of view of environmental safety and economic feasibility, recycled polyethylene is very beneficial as an inexpensive and affordable material for industrial production.

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Why is neglect of containers dangerous and how important is polyethylene recycling for the environment? In our life, polyethylene is present as a packaging container, but despite its narrow specialization, it is widespread everywhere. Almost every house has a package with packages that we collect from the principles of economy. But the trouble is, it turns out that the better the raw material, the more difficult it is to dispose of it and the longer the period of its decomposition itself.

The relevance of processing

Recycling of polyethylene raw materials is an important cost item for the city, as the material is characterized by incredible stability. He is not afraid of water, alkali, salt solutions. Polyethylene is not afraid even of organic and inorganic acids. It can be noted that these are good qualities, but they can turn into a number of problems.

First of all, it raises concerns ecological situation- According to rough estimates, the decomposition of polyethylene takes up to 300 years. If a simple plastic bag ends up in a landfill in the total mass household waste, it greatly complicates the processing process. Over time, this package undergoes thermal aging, gradually decomposing under the influence of sun rays, heat and oxygen. In the course of destruction, a harmless package releases harmful chemical substances into soil and water.

Alas, it is not possible to limit the production of plastics and polyethylene, but it is possible to rationally organize the entire workflow. Waste polyethylene, in fact, is a versatile material. Recycling of polyethylene, without exaggeration, can be called new life raw materials. Man is required to create and improve ways to collect and process raw materials in order to make the process cyclical. Polyethylene waste may well become everyday items.

Processing companies

AT last years the number of organizations processing this raw material is steadily growing. And it's not just about environmental issues but also in the prospects for the development of such a business. Polyethylene can be an excellent base for creating plastic panels, garbage containers, and all kinds of household containers. There is a certain scope for the imagination of entrepreneurs, although, of course, secondary polyethylene products involve some limitations.

The recycling of film and bags does not cause difficulties, since the structure of the materials used does not change for the most part, but the quality of the recycled raw materials decreases, and the scope of further application narrows accordingly.

Workflow features

There are several cycles of processing plastic bags, films. The first cycle has almost no effect on the decrease in consumer characteristics of new products. But each subsequent cycle makes its own “negative contribution”, making raw materials suitable only for the production of special materials.

According to existing technologies, six stages of polyethylene waste processing can be distinguished:

1. First comes the collection of raw materials: films, bottles, etc. household waste. Waste sorting can be done by manual or mechanical labor. If household waste during collection is divided into waste paper, glass, paper, PET, then it is possible to reduce the amount of garbage that needs to be disposed of by a third.
2. The collected raw materials are sent to washing machines. This stage is necessary in order to get rid of dirt, foreign objects and paper. If raw materials are delivered directly to collection points, then the receiver can check the condition of the film, bottles, waste paper in order to increase or decrease the price offered for them.
3. Next, the collected raw materials are crushed, for which crushing plants are used.
4. In case moisture or random solid impurities remain in the raw material, the centrifuge process is carried out.
5. Now the material is sent to the drying chamber, where heat treatment also takes place.
6. The work is completed and the material is ready for recycling. It can be used to make universal products: plastic film, bags, packaging, pipes.

Work in detail

And now let's try to take a closer look at the process of processing polyethylene into granules, because before that the process was considered only schematically. Of course, the right equipment is required for the job.

Well-established work is possible with:

• washing machine
• crushing plant
• centrifuges
• drying plant
• agglomerator
• granulator
• extruder

In production, the presence of a conveyor or pneumatic conveyor will be relevant, which will allow the process to be fully automated.

At home, it is almost impossible to establish an uninterrupted process for obtaining recycled polyethylene, but you can lay the foundation for promising business. First of all, you can declare the process of collecting raw materials, since without it such work is in principle impossible. Manual sorting of household waste will cost less than mechanical sorting, but you will have to start with a small amount of raw materials used.

Self-processing of the film allows you to get a dense waterproof fabric with a waterproofing function. The work process itself is simple - a piece of film must be laid between two parts of the fabric and ironed with an electric iron. The output is a three-layer composite material, as the film melts and penetrates into the layers of the fabric. With your own hands, you can get a composite material based on film, fabric and aluminum foil. The algorithm of operation is the same except for the fact that one layer of fabric is replaced by foil. Film, fabric and foil material is an excellent heat insulator. With the help of cross-linked polyethylene, many people equip a warm floor in the house.

For more benefit

Agglomerator - a device capable of processing film and bottles. Due to the temperature effect, an agglomerate is obtained - baked lumps from former bottles and films. The agglomerate can be sold already at this stage or go further and process it into pellets.

The polyethylene granulator allows you to increase the company's income from the collection and sale of secondary raw materials. The result is a product that technically outperforms its “powdery or scaly counterparts in the workshop” due to its small volume (and, accordingly, lower packaging and transportation costs), high flowability, minimization of losses and dust formation, lower risk of destruction and photoaging.

Why does an enterprise need an extruder? Just with its help, you can get a unique material - low-pressure polyethylene. The extruder starts working after the agglomerator has his say and turns the result of collection and processing into slurry. Now the molten mass of plastic goes through the forming hole, where it melts and creates threads that cool under water and are cut into small pieces. At the output, a HDPE granule is ready.

At low pressure

Low density polyethylene is widely used all over the world. It is an organic compound that resembles white wax. Recycled low-density polyethylene is obtained through the collection and recycling of bottles and pipes.

This material is not afraid of frost or chemicals. It does not feel shock and is not a current conductor. It should be added that this material is waterproof and does not react with alkalis, acids and salt solutions. HDPE decomposes under the action of nitric acid (50%), chlorine and fluorine.

How this product can be useful

1. Based on HDPE, accessories for swimming pools are made.
2. It is used in the process of 3D printers.
3. Such material is actual for work in the conditions of chemical and electric influence.
4. HDPE is good for creating anti-corrosion coating, food containers, bottles and collecting water connections.
5. In sports facilities, HDPE is used for the production of gymnastic hoops.
6. In restaurants, HDPE is a future plastic bag, plastic set or container. The HDPE bag rustles and wrinkles, so it is used for the so-called "T-shirts".
7. Pyrotechnics makers use HDPE to make their work more spectacular.

Outcome

The processing of polyethylene raw materials into granules makes it possible to significantly reduce the amount of garbage in urban landfills. Remember that polyethylene and plastic almost do not decompose. Meanwhile, on the basis of PET, you can make successful business. Don't throw away things that might come in handy later. Even a simple package, bottle, film - can be useful for business.

Pellet production has become one of the most popular and profitable enterprises today. And this case concerns both the production of granules from biological material, and from artificial.

Secondary granule or flex is the result of polyethylene processing. Also, flex is understood as secondary raw materials used for the production of chemical fiber.

AT pure form- it's cereal various colors from which plastic containers are produced. This means that plastic can be reused an infinite number of times. Also, chemical fiber obtained from recycled plastic is used in the production of many other goods and products - tiles, film, packaging tape, and so on.

The product obtained from recycled plastic is also classified depending on what material was originally used. These can be granules of propylene PP, stretch LLDPE, LDPE LDPE, HDPE HDPE, PS polystyrene.

LDPE, LLDPE granules are used to reduce the production cost of packaging materials for all fields. They are distinguished by the absence of toxins, odor, resistance to chemicals.

Polypropylene is impact resistant high temperatures, mechanical influences. They are also impact resistant chemicals, however, have a low level of frost resistance. This issue is solved by adding special components that raise the level of stability and eliminate this drawback. It is widely used in the manufacture and manufacture of furniture, dishes, packaging.

PVC granules are used in almost all areas due to their properties. During their production, there is practically no dust pollution, they are easily amenable to coloring and further technological operations.

HDPE granules are made from polyethylene of various pressure levels. Products made of low-density polyethylene have a high density index, which increases production costs and makes it possible to obtain products with high performance characteristics. Most often, packaging material and polymer pipes, household containers are produced from this material.

The raw materials for the production of fuel pellets are waste wood and peat processing industries. Quite often, waste from the agricultural sector is used - from corn and straw waste to poultry manure.

Pellet production technology + video how they do it

In fact, the technology for the production of polymer granules is very simple - the sorted raw materials are crushed in a crusher, after which the mass is heated and squeezed out of the hole, resulting in "threads" that are then immediately immersed in water, where they are cooled. And at the last stage, the already cooled threads are cut into granules by high-speed knives.

Video how to do it:

In addition to fixed lines, there are also mobile or mini plastic recycling plants. All units are in a special container, interconnected by all necessary contacts at the factory. In order for the installation to work, it is only necessary to bring electricity, water and sewerage to the place of its location to drain liquid waste.

Processing of PVC products is also carried out on separate special equipment. The line consists of the following units - a crusher, a mixer with two stages - cold-hot, with which PVC compositions are mixed, and a granulator, which includes an extruder, a granulator and a vibrating screen.

We all understand that waste is somehow recycled, but how is this done? Few people know. There are certain differences between the processing of industrial and household plastics, since polymers have different properties.

Similarly, secondary raw materials, that is, polyethylene, have their own properties, which often do not meet the requirements. This is comparable to the fact that the processing of polyethylene involves materials that differ in molecular structure. In addition, the plasticization process contributes to an increase in the quality of the processed material.

Recycling processes

Ordinary polyethylene, including the material used for packaging, has a long service life. It must be remembered that when using industrial film, it is exposed to atmospheric factors:

• temperature difference
• Sun rays
• the film may be covered with a layer of dust that is difficult to remove when carefully cleaning the film

As regards the conditions, the processing of polyethylene does not differ in principle from the processing of virgin material. But the recycling of polyethylene waste, in some cases, undergoes minor changes, so there are restrictions on the number of polyethylene processing cycles.

Our days

In modern times, the most advanced way to process polyethylene is to use an intermediate material to replace wood materials. The recycling process itself requires special cleaning of the secondary product (for example, containers for fuels and lubricants).

Most wide application recycled PE found the production of canisters by blow molding. These canisters are made completely on a waste basis or with extrusion, primary granulate (in this case, a layer of secondary polymer creates a core between 2 layers of 1st polymer). The resulting products are used for bottling various detergents not a small number of companies.

The second method is considered - irrigation pipes. The diameter of these pipes reaches up to 630 mm. When performing injection molding, recycled polyethylene has a lower percentage. This technology is used for cladding panels, garbage containers, etc.

As for the equipment, the processing of polyethylene has different kinds and stamps. Many manufacturers are engaged in the production of equipment, successfully entering the Russian market.