According to the structure and working principle of the screening machinery, it can be roughly divided into the following categories: (1) Fixed Screen Working part is fixed, the material screening relys on the sliding movement along the working face. More fixed grid screen is a kind of screen that applicated in the concentrator. Which is used for the coarse crushing or medium crushing in the pre-screening. It is simple in structure, convenient manufacture, does not consume power, we can unload the directamente ore to the screening surface. The main disadvantage are the followings: the productivity is low, the screening efficiency is low, which is generally only 50-60%. (2) Roller Screen The working face is constituted by the horizontally arranged rolling shaft, there are plates on the rolling shaft, the fine materials are obtained through the gap between rollers or plates. the bulk materials are driven by the roller to one end and finally discharged from the other end.
The concentrator rarely use this sieve. (3) the cylindrical sieve The working portion is the cylindrical shape. the entire sieve rotate around the axis of the cylinder, in the general case, the cylinder inclination axis is usually not very large. Fed into the material from one end of the cylinder, the finer level materials adopted by the screening of the working surface, coarse-coarse-grained materials cylindrical hole are discharged from the other end of the cylinder. The rotational speed of the cylindrical screen is very low, works smooth, power balance is good. But the sieve is easy to plug, screening efficiency is low, and the work area is small, productivity is low.
The concentrator rarely use it to make the screening equipment. (4) plane motion The sieve body wobbles or vibrates in-plane. According to their their plane motion trajectory, it is divided into linear motion, circular motion, elliptical motion and complex motion. Shaking and vibrating screen sieve (different from the vibrating grizzly feeder) fall into this category. Shaking screen crank linkage as transmission parts. Engine drives the eccentric shaft via a belt and pulley rotation, so the body do the reciprocating movement along a certain direction through the connecting rod. The movement direction Perpendicular to the strut or suspended rod line, duo to the the oscillating motion, the materials on the screening face move towards the discharge mouth at a certain speed, at the same time, the materials get screening. Compared with the above sieves, the shaking screen has the advantages of higher productivity and high screening efficiency. The disadvantage is that the poorly balanced driving force. Concentrator rarely use it nowdays, but replaced by the vibrating sieve whose structure is more reasonable.