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, air separation, 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 works well when sorting materials with large differences in density.

Vibration sorting effect of 75% plastic and 25% metal mixed materials

2 airflow sorting technology

Air separation, also known as wind sorting, by blowing a mixture of waste plastic and other materials by airflow, the density of the material is relatively close, and the light-weight material is far away, thereby achieving material sorting.

Density range of different plastics

Spiral airflow sorting

Pneumatic, fluidized bed sorting

Schematic diagram of pneumatic and fluidized bed sorting equipment

3 liquid sorting technology

The 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.

Flow sorting effect of waste plastics of different shapes and sizes

Grading flow sorting

Schematic diagram of fractional liquid flow sorting equipment

Hydraulic fluid flow sorting

Hydraulic fluid flow separation equipment structure and physical map

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 a combination of electrostatic action and magnetic sorting.

Frictional charging sequence of plastic

Electromagnetic sorting equipment