Concentration is a process by means of gravity centrifugal force or physical and chemical effects of pharmaceutical to realize agglutination of solid particles in suspension, thereby enhancing the solid phase concentration in suspension. This process is widely used in the concentration process of ferrous metals, nonferrous metals, rare metals and non-metallic. Nowadays, the main equipment to achieve this process is concentrator. Due to its easy operation and relatively low maintenance costs, it is widely used in various industrial sectors. In the mineral processing equipment, concentrator is mainly used for the concentrate product concentration, tailings recycled water handling as well as dehydration condensed of intermediate products. 

There are now many types and specifications of concentrator. Generally speaking, according to the structural features, they can be divided into the traction thickener and Center Drive Thickener, or divided into single-layer concentrator and multi-layer concentrator. traction thickener, in accordance with its structure, can be divided into the peripheral rack drive, surrounding roller transmission drive and surrounding rubber tire drive etc. The materials of concentrated pools are steel pull system, wood or concrete. 

Currently the concentrator home and abroad is basically in a stable stage, and the development and improvement are not significant. The concentrators used in the mineral processing plant are major of center-drive, because of their reliable operation. Some mineral processing plant add inclined plate in the small and medium-sized concentrator, in order to improve the processing capability of unit area. Moreover, the multilayer (3-5 layers) concentrator is researched in order to reduce floor space. Many countries have produced complete series and more specifications. According to the structural features, they can be divided into several types: 

(1) Center shaft driving inspissation concentrator: generally the small diameter concentrator is with such a structure. Its special cylinder leaves the rake frame rotating through the center of rotation axis. The diameter of such concentrator is generally no more than 20 to 25 meters.

(2) Center drive concentrator: structural features of this kind of concentrator is that in the center of the concentrated pool there are reinforced concrete columns above the surface, so as to support the machine, Center Drive drives harrow frame to rotate. The diameter of this type of concentrator is not too large, usually about 20 meters, but the maximum can reach 50 meters or more.