CSG News

Do you know the tech of waste plastic sorting?

FROM:MSW DATE:2021-07-28 11:36:21 CLICK:481  

There are many ways to sort waste plastics. Below, we will look at waste plastics sorting technology from a special perspective.

Plastic has good chemical stability, electrical insulation, thermal insulation and mechanical properties, and is low in density and easy to process. Therefore, it is widely used in many fields such as agriculture, machinery industry, construction, transportation, national defense and medical treatment.

However, with the increase in the use of plastic products, plastic waste is also increasing, which has a serious impact on the ecological environment. Therefore, how to recycle waste plastics and recycle them is an important issue for the sustainable development of the plastics industry and the key to protecting the ecological environment.

The recycling methods of waste plastics mainly include energy recycling, physical recycling and chemical recycling.

Energy recovery is to obtain heat energy from waste plastics through combustion; physical recovery is to remelt and pelletize waste plastics or process them into new products after sorting, cleaning, crushing and other processes; chemical recovery is through thermal decomposition or chemical decomposition And other technologies to convert organic components in waste plastics into petrochemical raw materials.

In terms of waste plastic sorting technology and related equipment directions, the recycling methods of waste plastic recycling mainly involve physical recycling. Physical recycling has the advantages of simple processing technology, low equipment cost, and low investment. my country's waste plastic recycling industry has a considerable production scale, and so far, it is also one of the main ways of recycling waste plastics in my country.

For a large amount of waste plastics, we need to carry out pretreatment. If the mixed waste plastics are directly machined, the product value is low, the performance is poor and unstable. Therefore, in order to increase the recycling of waste plastics and increase the value of recycled products, mixed plastics The sorting is especially important.

The sorting of mixed waste plastics generally uses the chemical composition, light transmittance, density and other characteristics of the plastics. The waste plastics in the mixed state are purposefully separated into single components to obtain a uniform material of waste plastics, so that the waste After the plastics are sorted to ensure that the purity of the plastics of specific materials meets the relevant requirements, it is conducive to making higher value and better recycled products and maximizing economic value.

For waste plastic sorting technology, it can be divided into traditional sorting methods and modern sorting methods.

Traditional sorting methods include manual sorting, density sorting, wind sorting, etc.; modern sorting methods include color sorting, near infrared spectroscopy (NIR) sorting, etc. Different methods are effective for separating mixed waste plastics, but these methods have their own advantages and disadvantages in terms of use range, separation efficiency, accuracy, and industrial applications.

Color sorting is a technique for separating plastics based on the color difference. Its working principle is to pass the waste plastic through several color filters, so that the waste plastic reflects different brightness, and the computer system converts it into a current value and recognizes it. When passing through the separation device, it can realize different color plastics. Effective classification. This method is suitable for separating plastic products with different colors. The disadvantage is that it cannot be used to identify the material types of waste plastics.

Different types of plastics have different spectral properties. Scanning polymers through different optical media can quickly and accurately identify the types of waste plastics. At present, the optical sorting methods used in the identification of waste plastics mainly include X-ray sorting (XRT/XRF), near-infrared spectroscopy (NIR), mid-infrared spectroscopy (MIR), laser spectroscopy (LIBS), etc. . Among them, near-infrared spectroscopy sorting is currently used in the field of waste plastic sorting due to its advantages of easy acquisition of spectral analysis signals and rich information, coupled with the spectral band overlap and low absorption intensity of the spectral region itself. The most extensive and large-scale optical sorting method. This method is suitable for the identification of most plastics, and is fast, reliable, and highly sensitive, but the disadvantage is that it cannot identify dark plastics. Therefore, in the sorting process of waste plastics, it is often used in combination with color sorting to improve the sorting effect.

—— MSW ——
CSG Copyright 2000-2018 / Article by COLOR SORTER