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GRANDUC IS SITUATED AT THE BASE OF THE LARGE MOUNTAIN. |
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Granduc - Milling Cont...
FINE CRUSHING
 During its journey from the underground
ore pocket a total of 10 conveyors were used to carry the selected millfeed to
fine-ore and pebble-storage bins.
As the minus 6-in. ore reached the top
of the concentrator building a Tyler double-deck vibrating secondary feed
screen scalps plus 4-in. material as feed to the 7-ft. Symons heavy duty
secondary cone-crusher and a middle cut for pebble-grinding media. Minus 2-in.
undersize passed to a fine-ore screen from which the over 1-in. coarse fraction
goes to the 7-ft. Symons tertiary cone-crusher and the minus I-in. to fine-ore
storage. Secondary-crusher discharge is screened to yield tertiary-crusher feed
and fine ore and tertiary- crusher discharge is directly to fine-ore storage.
The pebble- material bin has a capacity of 2260 tons and the three fine- ore
bins each have a capacity of 3600 tons.
The tertiary crusher was operating in
open circuit but provision was made for a closed circuit whenever required in
the future. As
in the rest of the plant, electrical, electronic, and mechanical 'control
apparatus plays an important role in the smooth running of the crushing
section. For instance, each conveyor could be operated from start/stop buttons
mounted locally and on the fine-crushing control room console; each conveyor
was shut down in the event of a plugged discharge-chute condition with sensing
done by a mercury-tilt switch; each conveyor is equipped with emergency
stop-pull cords; all start pushbuttons have latch relays and no opportunities
were provided for jogging, interlocks require the immediate downstream conveyor
to be running before a conveyor could be energized.
Belting
was supplied by a Japanese manufacturer and was equipped with 3-roll, 35-degree
trough, carrier idlers, and flat-return idlers by Hewitt-Robins.
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