Screening efficiency/capacity

Method of Feed The screening machine must be fed properly in order to obtain maximum capacity and efficiency. The feed should be spread evenly over the full width of the screen cloth and approach the screen surface in a direction parallel to the longitudinal axis of the screen and at as low a practical velocity as is possible. 

By adding a screen on a portable mounting, a complete, compact mobile crushing plant of high capacity and efficiency for use in any location is provided. 

The performance of screens is assessed on the basis of two criteria efficiency, and capacity. 

In industrial screening, capacity is important in addition to efficiency. The capacity of a screen is measured by the mass of the material fed per unit time to unit area of the screen. 

Efficiency and capacity oppose each other, and in order to obtain maximum efficiency the capacity must be small. A large capacity is achievable only at the expense of a reduction in efficiency. In practice, a reasonable balance between capacity and effectiveness is struck. Although accurate correlations are not obtainable for judging or calculating these operating characteristics of screens, certain principles apply, and these can be used as guidelines in grasping the basic features of screen performance. 

Vibrating screens, horizontal and inclined screening surfaces vibrated at high frequencies (1000 to 7000 Hz). High capacity units, with good separating efficiency, which are used for a wide range of particle sizes. 

Fig. 5.1a shows the slurry packing system that 1 use. This operates at a fairly low pressure, as I am not especially interested in producing columns with very high efficiencies, but rather in saving on the cost of commercial columns. The pump and high pressure valve are rated for pressures of 500 bar (7500 psi) and 400 bar (6000 psi) respectively. The slurry reservoir is a stainless steel tube 85 cm long, with a capacity of about 50 cm3. The method is not hazardous unless there is air trapped in the high pressure line nevertheless it is advisable to use a safety screen. 

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