Crushing Circuit Overview

The crushing circuit at typically is a three-stage (tertiary) operation that utilises a primary jaw crusher, a secondary cone crusher and two tertiary cone crushers (operating in parallel). This circuit has been selected to match the competency of the ore, and the production rate requirements from the mine.

General Description

The Run of Mine (ROM) ore is fed to a 170 tonne capacity ROM bin by a front-end loader through a 800mm square aperture static grizzly. The oversize from the grizzly is broken with the rock breaker which is installed adjacent the ROM bin.

A plate feeder and vibrating grizzly transfer the ore from the ROM bin to a single-toggle jaw crusher. The jaw crusher operates with a closed side setting (CSS) of 130-140mm and is powered by a 200kW motor.

The jaw crusher product discharges onto a vibrating feeder together with the grizzly undersize. The vibrating feeder transfers the ore onto CVR01. These products combine with the discharge of the secondary cone crusher on CVR01 and then transfer to the screen feed conveyor CVR02. Product from the tertiary crushers’ combines with the primary and secondary crushed products on CVR02.

The ore is then discharged from CVR02 onto a double-deck banana screen via a diverging feeder. This screen is fitted with 14mm and 45mm slotted aperture rubber/poly cloths in the lower and upper decks respectively. The oversize from the upper deck reports to the secondary crusher feed conveyor CVR03. The lower decks’ oversize reports to the tertiary crusher feed conveyor CVR04 and the undersize fraction from the lower deck reports as final product to the fine ore bin via CVR05, CVR06 and CVR07.

Secondary crusher feed (+45mm) is discharged into the secondary crusher feed chamber via surge bin equipped with a variable-speed vibrating feeder. The secondary crusher is a standard head cone crusher which operates at a closed side setting of ~30-35mm and is powered by a 375kW motor.

Tertiary crusher feed (+14mm -45mm) is directed from CVR04 onto a splitter plate, which distributes feed into both surge bins. The surge bins are equipped with two variable-speed vibrating feeders which discharge material into the chambers of the tertiary cone crushers. The tertiary crushers are equipped with short heads which operate at a closed side setting of ~10- 16mm and are powered by 375kW motors.

The crushing circuit produces a product of 80% passing ~9mm at a design rate of 515tph. A diagrammatical representation or flowsheet of the circuit is shown on the following page.