According to the machinery sifting structure and working principle are more or less the following categories:
(1) a fixed part of the work of the screen fixed by the material along the face of sliding material by receive screening. Fixed frame screen in the application of more of a concentrator, for the general rough or broken in pieces before the pre-screening. Its structure is simple and easy to create. Power consumption does not have a direct bearing on the unloading of ore to the surface of the screen. The main disadvantage is low productivity, low efficiency of the screen, generally only 50-60%.

(2) roller screen face is arranged by the horizontal axis constitute a rolling root, a plate-axis, fine-grained materials from in-line or through the gap between the plates. Bulk materials from one end to the roller-led move from the end of the discharge. Concentrator in general in this little screen.

(3) as part of the work of the sieve cylinder-shaped cylinder, the entire screen around the rotary cylinder axes, the axis generally downloaded into a small angle. Materials from one end to the cylinder into the small-level work surface materials from the barrel through the sieve, coarse-grained materials from the other end of the cylinder exhaust.

The screen cylinder low speed, steady work, good balance of power. But it is easy to plug the sieve, sieve inefficient work of the small size, low productivity. Concentrator rarely use it to make a screening device.

(4) flat screen body movement is a swing plane or vibration. Their flat trajectory is divided into linear motion, circular motion, elliptical exercise and sports complex. Sieve shaker and shake fall into this category.

Shake the screen is as a crank linkage transmission parts. Motor through the belt and pulley driven eccentric shaft rotation, so that the connecting rod through the body along a certain direction for movement back and forth. Movement direction perpendicular to the body or hanging strut bar center line, as the body of the swing movement, so that the screen on the surface of the material to a certain speed to the nesting mobile terminal, at the same time the material has been screening.

Sieve and shake some of the above sieve, screening efficiency and productivity of its relatively high. The disadvantage is that its balance of power difference. Concentrator now rarely use it, and the structure was more reasonable to replace the shaker.

Concentrator in the most widely used, according to the transmission mechanism, and can be divided into the following categories: eccentric shaker, shaker of inertia, self-shaker Center, the resonance screen.