gradually increase along the longitudinal direction of the deck. This
is due to the material layer being thin at the discharge end where
particles easily pass through the screen. In the stable state, the linear
vibration screening has the lowest increment in screening efficiency
for each section. When the increment of screening efficiency
is defined as the ratio between the average efficiency of Sections 6
and 1 the value is 2.6. The total screening efficiency for the linear
mode is also the lowest with a value of about 0.66.
The circular screening mode has a screening efficiency at the
first section of the screen deck, which is at the feed end, and is lowest
because of the thick material layer located there. The incremental
screening efficiency is a maximum of 4.4 and the total efficiency
is a maximum of 0.78.
The elliptical screening process has an increment of screening
efficiency and a total efficiency of 3.5 and 0.72, respectively. Therefore,
the screening modes have a significant influence on the
screening efficiency. Compared to the linear vibration mode, particles
on a circularly or elliptically vibrating screen deck show a
higher separation efficiency.
Further analysis of particle penetration for the different vibration
modes was done by examining the size of the undersize materials
produced in the steady state. The volume fraction for both
small and near-mesh size particles along the underside of each section
of the screen deck is shown here as Fig. 6. In that figure, VYi
and VNi are the average volume of small and near-mesh size particles