In early June 2008, Kennards Concrete Care supplied a Darda C12 Hydraulic Splitter for a trial at the Ridgeway Gold Mine, located near Orange in the central west of NSW.
The Darda C12 Hydraulic Splitter was used to break some oversize boulders which had been specially selected and trucked from the production level 850 metres 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,” said Stephen Duffield, Transition Manager for the Ridgeway Deeps project.
“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.
However, Stephen Duffield could see that the splitter offered advantages in the underground environment.
He contacted Daniel Jeffries at Kennards Concrete Care at Artarmon in Sydney to supply their Darda C12 splitter so that the project personnel could test its capability and efficiency on run-of-mine rock.
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 45mm 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.
Kennards Concrete Care have hire centres in Sydney, Melbourne and Perth and a new outlet in Brisbane.