Multi-deck screens

For dry bottom ash, the primary option is to screen to the appropriate size for the end use. The degree of screening is ultimately determined by the customer, but is primarily intended to control the top size and minimize the amount of fines. Incremental screen sizes can be included if necessary on a multi-deck screen to meet... 

The most widely used design is the inclined vibrating screen. These use decks at some 15° to 20° to the horizontal mounted on a vibrating frame to transport materials across and through the screen. Such screens can be used in series to produce a number of sized fractions. Alternatively, multi-deck screens can be used, in which two, three, or even four decks are mounted on one frame, with the largest aperture mat being at the top and the smallest at the bottom of the frame (Fig. 5.8). With all designs, the material should be fed uniformly across the width of the deck at a steady rate to maximise the effectiveness of the screen. 

The crushed ROK lime is then fed to a multi-deck screen, which produces a secondary fines fraction (e.g. less than 5 mm), granular, and pebble , lime fractions (e.g. 5 to 15 mm and 15 to 45 mm). Oversize lumps (e.g., greater than... 

Mechanically operated screens are vibrated by means of an electromagnetic device as shown in Figure 1.40, or mechanically as shown in Figure 1.41. In the former case the screen itself is vibrated, and in the latter, the whole assembly. Because very rapid accelerations and retardations are produced, the power consumption and the wear on the bearings are high. These screens are sometimes mounted in a multi-deck fashion with... 

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