Coal fired boilers in thermal power plants burn coal gangue with a certain proportion of particle size. The particle size of the coal in the coal mine is uneven, and most of the material particles in the coal are qualified and do not require repeated crushing. This part of the material generally accounts for 35-75% of the entire material. There are many screening equipment in China now. The commonly used screening equipment can be divided into two categories: vibration conveying type and forced conveying type, each with its own advantages and disadvantages. It is best to select based on the parameters of the material situation.

Screening machines are divided into two types: fixed screens and movable screens, with movable screens further divided into rotary screens and vibrating screens. Fixed screens are mostly installed with grates above the inlet of the crusher to prevent oversized materials from falling in. Rotating screens are mostly made by folding plate screens into polygonal or circular cylindrical bodies. They have a simple structure and long lifespan, but low productivity, bulky body, and are rarely used.