A University of Queensland study, in conjunction with one of Australia’s largest gold mines, may change the way waste rock is handled at open-pit mine sites around the world.
The researchers are from UQ’s Centre for Geomechanics within the Cadia Hill Gold Mine near Orange in New South Wales, one of Australia’s largest gold mines. Mining at Cadia Hill Gold Mine began in 1998 and production averages almost 300,000 ounces of gold and 23,000 tonnes of copper per year.
The mine’s owners, Cadia Holdings, are the project’s industry sponsor as part of a $520,780 Australian Research Council (ARC) Linkage grant, running from 2004 to 2007.
Project chief investigator Associate Professor David J Williams and PhD student Tim Rohde, analyse data from 24 tanks or lysimetres buried beneath the 0.7-hectare, 15-metre-high trial waste rock dump, together with data collected from other instrumentation.
Dr Williams said the study, also involving Dr Stolberg from UQ and Professor Ward Wilson from the University of British Columbia, is the most sophisticated of its kind in the world.
“It taps into often-expressed concerns by environmentalists that rainfall flowing through some mine waste dumps has the potential to contaminate the surrounding environment, including the groundwater,” he said.
“If we can understand the way in which rainfall is both stored and released by waste rock dumps, they can be better designed and operated to limit seepage during operation and after closure.”
After the progressive construction and instrumentation of the trial waste rock dump at Cadia, lasting almost two years, the researchers now continuously monitor seepage from tipping bucket gauges connected to the two-metre-diameter lysimeters. These results are downloaded to the researchers’ computers at UQ and so far, six months’ worth of data has been collected.
As well as monitoring seepage through the trial dump, various low permeability soil/rock covers are being trialled on the top of the dump to assess which is most effective in limiting ongoing infiltration into the completed dump.
The study has the potential to change the way waste rock dumps are constructed and covered at open-pit mines, which constitute about 75 percent of mines in Australia.
Media: Dr David Williams (07 3365 3642, 0417 193 591) or Shirley Glaister at UQ Communications (07 3365 2049).
