In the life of a modern person, polyethylene is used everywhere. Almost every home has a variety of packages. The better the raw materials, the more difficult it is to dispose of and the longer its decomposition. Polyethylene waste is recycled to produce new products. This is described in the article.
Disposal
The widespread use of polyethylene has caused an environmental problem - waste accumulation in landfills. According to estimates, the share of these products takes 8-10%. The material does not decay, it is resistant to acids and alkalis, almost insoluble, it takes many years to decompose, and hazardous substances that pollute the soil and water bodies are released.
With burning, polyethylene waste does not burn completely, forming toxic dioxins that are harmful to all living things: poisons accumulate in the body, which causes dermatitis, ulcers, and mutations. Pyrolysis from this raw material has not been widely used - it is economically profitable with a large amount of raw materials (over 20 thousand tons per year).
The best option is to hand over the polyethylene. Recycling allows the use of raw materials for recycling. This is the possibility of resource saving, cheaper products, cost reduction.
Types of waste
Polyethylene waste differs in form, composition, location, contamination, level of preparation for secondary use. They are divided into several groups:
- Technological defects (2-10%) - practically does not differ from air-conditioning products. It is used as a returnable raw material or low-grade commercial products.
- Industrial waste - films, containers, containers, pipelines, cable braids, non-working products.
- Part of the waste in landfills - films, bags, bottles, household items.
- By the level of preservation: insignificant destruction and partial loss of the necessary characteristics.
Polyethylene waste is mixed with other waste. There are 2 directions for the recycling of polyethylene - the allocation of homogeneous products and processing in a mixture of waste.
Recycling
Reception of polyethylene waste is carried out by specialized companies. From the type of product determine what the technological cycle of processing will be. Usually it includes sorting, cleaning, fractionation, grinding, crushing, agglomeration, granulation and product formation.
Large debris is cut using circular saws or band saws. For small products, jaw or rotary crushing units, hydraulic choppers, devices cooled by liquefied carbon dioxide are suitable.
Cleaning from contaminants is carried out in the places of washing and on the washing lines with the function of regeneration of solvents. Polyethylene is removed from thermoplastics using a screening method with separation or flotation. To reduce the volume, degassing, cleaning products are sintered. Agglomerate is used as a commercial product or used for granulation to create secondary granules of the highest quality.
Recycled polyethylene has a high melt viscosity. Its granulation is carried out with high temperatures in devices in which rotary knife grinding crushers, pumps for melt are present. These granulators are needed for processing, degassing and modifying waste.
Features of work
There are several steps involved in processing packages. The first cycle has virtually no effect on reducing consumer characteristics of new products. But with each step, the raw material acquires negative characteristics, because of which it can be used for special materials. Waste low-pressure polyethylene is used to produce new products. Processing technology is as follows:
- There is a collection of raw materials: films, bottles, garbage. Sorting is performed by manual or mechanical labor. If the waste is separated into waste paper, glass, paper, PET, then it will be possible to reduce the amount of garbage for disposal.
- The raw materials go to the washing device. The stage is required to eliminate dirt, foreign objects. If the products are handed over to collection points, then quality is checked to determine the cost.
- Raw materials are crushed by crushing apparatus.
- If it contains moisture or impurities, processing is carried out in a centrifuge.
- The material is sent to a drying chamber for heat treatment.
- The work is completed and the material can be reused. They make universal products - plastic films, bags, packaging containers, pipes.
What is derived from waste?
The collection of polyethylene waste allows you to get various products. Mixtures with a large number of foreign inclusions are processed using casting or intrusion at low pressure. This low-cost option allows you to get lightly loaded products for decorative street fencing.
Reception of polyethylene waste with a short period of use (containers, films, bottles for single use) is carried out for processing into products of this type. If the materials have a crushed structure, then large products with low strength are obtained from them.
Nowadays, a sphere has been developed for the production of composites from secondary polymers and fillers: wood sawdust, crumb rubber. They are used in the manufacture of containers, tiles, furniture, decorative elements for machines.
The secondary granule is used as an additive to polyethylene in the manufacture of typical products or as a binder in composites for pressure pipes and large containers. From this raw material create containers and packaging for non-food products, building films, pipelines. This direction, although complex, is actively developing.
Total
Thanks to recycling, it will be possible to reduce the amount of garbage in urban landfills. Polyethylene and plates practically do not decompose. But on the basis of them new products are obtained that come in handy in various areas of human life.