Mixed waste plastics are difficult to recycle or reuse, and the value of waste plastics must be classified to achieve effective recycling. There are many sorting techniques for plastics, including vibration sorting, airflow sorting, liquid sorting, electromagnetic sorting and photoelectric sorting.

1 vibration sorting technology

The vibration sorting technology utilizes the reciprocating motion of the vibrating bed to drive the vibration of the material on the bed surface. The main principle is to use the frictional force and inertial force generated between the material and the bed surface to form different displacement movements of the material particles, and achieve the separation effect by the displacement difference between the material particles. Vibration sorting is better when sorting materials with different density differences.

2 airflow sorting technology

Airflow sorting, also known as wind sorting, uses a mixture of waste plastic and other materials to blow a dense material with a relatively close distance and a lighter weight material to travel farther away, thereby achieving material sorting.

3 liquid sorting technology

Liquid sorting technology utilizes the difference in density between liquid and plastic particles to achieve sorting of different types of waste plastics. The study found that the factors affecting the sorting effect are the density of plastic materials, the properties and size of plastic materials.

4 electromagnetic sorting technology

Magnetic separation technology is a technique that uses magnetic differences of various materials to perform sorting under the action of magnetic force and other forces. Electrostatic separation technology uses a variety of plastics with different electrical conductivity and electrostatic properties of the electric field on the plastic for sorting. Electromagnetic sorting technology is the interaction between electrostatic action and magnetic sorting.

5 photoelectric sorting technology

Photoelectric separation is based on the automatic separation of different plastics in spectral properties, and is divided into absorption spectrum (such as infrared, ultraviolet absorption spectrum), emission spectrum (such as fluorescence spectrum) and scattering spectrum (such as Raman spectrum). Wait for 3 types. The three elements that resolve the infrared spectrum of a plastic material are the peak position, shape, and intensity.

Sensor-based sorting system

According to the detection principle of sensor sorting, automatic sorting technology is divided into the following six categories:

Color recognition sensor (COLOR)

By analyzing the visible, infrared, ultraviolet and other ranges of the spectrum of the material, the color of the material is identified for sorting

Near infrared sensor (NIR)

The sorting judgment is performed according to different reflection spectra exhibited by different materials.

X-ray perspective (XRT)

Sorting is judged according to the different atomic densities of different kinds of materials.

Electromagnetic sensor (EM)

The sorting is judged according to the different conductivity and magnetic permeability of the material.

Visible spectrum sensor (VIS)

Visible spectrum identification and sorting judgment for transparent and opaque materials.

X-ray fluorescence technology (XRF)

Sorting and judging according to the atomic properties of the material

Sorting technology has always been the most difficult and critical technical link in the resource recycling industry. The above is a brief introduction to sorting technology.