BHP has completed a heap leach development trial it says confirms the technology’s viability to extract copper, uranium, gold and silver at the Olympic Dam mine in South Australia.
The company produced 19 tonnes of ‘good quality’ copper during the trial, most of which went back into the smelter and off to customers, though the company “kept a little to ourselves to commemorate the achievement.”
“The promising results from this trial supports our positive outlook for Olympic Dam, given forecast demand increases for copper and the optionality we are building for this world-scale resource,” BHP Olympic Dam general manager of surface processing Chris Barnesby said.
“Whether we deploy heap leach at Olympic Dam is a matter for future consideration, as there are many factors involved including passing through our capital allocation framework.”
The seven-year research trial was run by international testing agency Bureau Veritas under the direction of BHP, with support from the South Australian Government.
Olympic Dam’s test work progressed from lab scale columns and bench tests, before culminating in a “world class” testing facility at Wingfield, according to Bureau Veritas manager of major projects Clint Bowker.
Heap leaching works by drip-feeding acid through a large stockpile (or heap) of ore to leach out metals. The technology has the potential to deliver lower costs, increased scalability, reduced portable water use and the ability to process lower-grade ores.
BHP uses heap leaching at its copper operations in Chile, however, Olympic Dam’s polymetallic properties require a different approach.
“The test work showed how BHP and Bureau Veritas could partner to develop and deliver technology-driven innovative solutions to greater South Australian resources, proving that organisations can work collaboratively to resolve challenging ore bodies,” Bowker said.
“The facility will remain available as a resource to the mining community for further research as the facility will be in care and maintenance for the future.”
Separate to the heap leach trial, BHP continues to progress studies for the brownfield expansion project (BFX), which seeks to potentially increase Olympic Dam’s production to between 240,000 and 300,000 tonnes a year.