ydraulic machinery manufacturer Atlas Copco has supplied the largest pedestal boom rock breaker in Africa to Anglo Platinum's (Angloplat's) PPRust platinum mine. Rock breaker division manager Gordon Jackson says that the machine is performing to the expected standard.

The 28-t machine, with a boom and hammer, is powered by a 110-kW hydraulic power pack which, in turn, is electrically powered.

The rock breaker is specifically designed to suit the harsh environment that accompanies South African hard rock mining, where one of the requirements is continual operation.

The mine sited the large rock breaker to work alongside its very large crusher, which is the largest primary gyratory cone crusher in the Southern Hemisphere.

The rock breaker's boom-mounted hammer is able to reach right into the large crusher to break any oversized rock fractions, some of which may be up to two metres in diameter.

The rock breaker's slewing mechanism is purpose-designed specifically for the work it has to perform, providing a significant benefit in that it is well suited to the task and thus efficient.

Another noteworthy benefit of the machine comes in the form of its flexible, shock-absorbing base. The body of the machine is cushioned against the base plate through a series of heavy-duty rubber pods, although the base plate itself is bolted directly onto the concrete.

Jackson says that this shock-absorbing design is exclusive to Atlas Copco large rock breakers. If the design did not embody this shock-absorbing flexibility, the sheer size and weight of the machine would tear the hold-down bolts from the concrete base.

The shock-absorbing system also protects the equipment from excessive vibration.

The electric-over-hydraulic control system makes for a smooth and easy operation, which is performed remotely from a control room overlooking the crusher. This arrangement keeps the operator away from dust and noise exposure.

The routing of commands from the remote control room to the rock breaker is by means of a single cable. The simple communications system has been well-proven by Atlas Copco historically on rock breakers that have been supplied all over the world.

Atlas Copco will be training the machine operators, although the company says its rock breaker's twin joy-stick controller is easy to master.

The company will also be training the mine's technical staff in all aspects of machine maintenance, while providing back-up support and service from its Johannesburg office.

Jackson states that, since its installation, it has performed without incident and no alterations have been necessary.

The installation came as part of Angloplat's PPRust expansion project, which is to increase milling capacity at the mine from 385 000 t/m to 985 000 t/m, producing an additional 230 000 platinum ounces a year. To this end, new milling and concentrating capacity is being installed at the pit, together with a more efficient mining design.

The total cost of the project, which is facing potential delays, is expected to be about R5,8-billion, which is up from an earlier estimate of R4,25-billion.

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