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 850m below surface.

Stephen Duffield, Transition Manager for the Ridgeway Deeps project said that they are expecting to have to break a lot of oversize rocks when they start the new Ridgeway Deeps underground mine, possibly up to 100 per day.

Stephen Duffield said that the Ridgeway Deeps mine will use the block caving technique to extract the gold and copper bearing ore.

He also says that it is a cost-effective way to mine, using gravity and in-situ stresses to break up the ore body, but the resulting fragmentation can be coarse.

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

Stephen Duffield says that traditionally 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 – 140MPa.

For the trial, five oversize rocks (ranging in size from 2 to 4m³) 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 has hire centres in Sydney, Melbourne and Perth and a new outlet in Brisbane.