Boulder split in record time

A Hydraulic Splitter has been used to successfully break oversize boulders at Ridgeway Gold Mine, located near Orange in the central west of NSW.

A Hydraulic Splitter has been used to successfully break oversize boulders at Ridgeway Gold Mine, located near Orange in the central west of NSW.

Kennards Concrete Care supplied the mine with a Darda C12 Hydraulic Splitter to help break up some boulders that had been trucked from the production level 850 m below surface.

“We are expecting to have to break a lot of these oversize rocks when we start the new Ridgeway Deeps underground mine, possibly up to 100 per day,” transition manager for the Ridgeway Deeps project Stephen Duffield said.

“The Ridgeway Deeps mine will use the block caving technique to extract the gold and copper bearing ore. It is a very cost-effective way to mine, using gravity and in-situ stresses to break up the ore body, but the resulting fragmentation can be coarse.

“We are investigating safe and efficient ways to reduce boulders in size such that they can be easily handled by our underground loaders and fed into the crushers.

“Traditionally, we have relied on explosive methods to break rocks but this adds in blasting fumes, fly-rock and possible damage from shock waves, along with strictly controlled handling of hazardous materials. The hydraulic splitter has none of these issues.”

In Australia, experience with hydraulic splitters has been mainly in the demolition industry, particularly in sensitive built-up areas where blasting is prohibited.

The five boulders tested were all volcanic type rock with an estimated unconfined compressive strength (UCS) of 110 — 140 MPa.

For the trial, five oversize rocks (ranging in size from 2 to 4 m3) were pre-drilled underground with one 45 mm diameter hole each then trucked to surface.

The splitter was inserted and engaged in each rock and the process recorded. In each case, the initial crack appeared in the rock within 15-20 seconds.

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