Figure 8-14.-Typical batch plant cumulative scale settings and cycle.
is screened into different sizes and stored by size in
separate bins.
From the hot bins the aggregates are deposited into
a weigh-hopper. Coarse aggregates are usually the first
to be deposited into the weigh-hopper, the
intermediate-size aggregates next, and the fine
aggregates last. This sequence is designed to place the
fines of the aggregates at the top of the aggregates
deposited in the weigh-hopper where they cannot leak
out through the gate at the bottom of the weigh-hopper,
This system also allows the most efficient utilization of
the available volume in the weigh-hopper. The
weigh-hopper is suspended from scale beams and the
scales indicate the weight of the full amount of
aggregate entering the hopper.
When each size of aggregate is deposited into the
weigh-hopper, the weights to be drawn from the hot bins
are marked on the scale dial. Because the scales indicate
the weights cumulatively, the dial must be marked
accordingly. Figure 8-14 shows how the cumulative
scale settings are used to control the proportion of
aggregates drawn from each bin.
8-13
