Classifiers vari-mesh

Another type of classifier directs an air stream across a stream of the particles to be classified. An example is the radial-flow classifier Kennedy Van Saun Corp.), which Features adjustable elements to control the flow and classification. A further development on this principle is the Vari-Mesh classifier Kennedy Van Saun Corp.), which controls classification by adjustable flow baffles. A change in direction of air flow is the operating principle of the reverse-flow Superfine classifier Hosokawa Mineral Processing Systems). 

The products are an oversize (underflow, heavies, sands) and an undersize (overflow, lights, slimes). An intermediate size can also be produced by varying the effective separating force. Separation size maybe defined either as a specific size in the overflow screen analysis, eg, 5% retained on 65 mesh screen or 45% passing 200 mesh screen, or as a d Q, defined as a cut-off or separation size at which 50% of the particles report to the oversize or undersize. The efficiency of a classifier is represented by a performance or partition curve (2,6), similar to that used for screens, which relates the particle size to the percentage of each size in the feed that reports to the underflow. 

The net production in wet grinding in the Bond grindability test varies from 145 to 200 percent of that in diy grinding depending on mesh [Maxson, Cadena, and Bond, Trans. Am. Int. Min. Metall. Pet. Eng., 112, 130-145, 161 (1934)]. Ball mills have a large field of apph-cation for wet grinding in closed circuit with size classifiers, which also perform advantageously wet. 

The Bradley pneumatic (air-swept type) Hercules mills Bradley Pulverizer Co.) are centrifug ring-roll-type pulverizing mills which can be fitted with either two or three rolls. These mills are suitable for the pulverization of many materials to produce as coarse as 98 percent minus-20 mesh to as fine as 99.5 percent minus-325 mesh. The size of the pulverized product can be varied by adjusting the fineness selector mounted on top of the mill. Capacities range from 225 kg/h (500 Ib/h) to 90 Mg/h (100 tons/h). When combined with the superfine Bradley IU 4C classifier, this mill can make a product finer than 11 [Lm. 

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