Newcrest Mining’s chief executive Sandeep Biswas has revealed the Cadia Valley Operations mine may be out of action for “anywhere between one to six months”.
Operations at the gold and copper mine were brought to a halt on Friday evening after the partial collapse of the wall separating its northern and southern tailings dams.
The company is looking into whether production could resume with tailings – the mine’s post-production waste material – being pumped into the unaffected southern dam or the disused Cadia Hill open-cut pit.
In a webcast published on Newcrest’s website on Thursday, Mr Biswas was unable to specify when production of Cadia's copper and gold would resume.
When questioned about how long it would take to have those alternative tailings-storage options approved and up and running, Mr Biswas revealed it would be at least a month.
“That depends completely on the regulator, and we will be submitting our application as soon as possible,” he said.
“There are two stages, the formal approval process stage and then you have the construction stage. It can take anywhere between one to six months.
“We are unable to be specific right now on when we will return to production.”
Mr Biswas said the company was investigating reactivating some of the mine’s capabilities while it waits for either of the alternative tailings-deposit options to be given the green light.
“Even without access to tailings storage, we're looking at whether it makes the most sense to recommence mining operations in order to stockpile ore on the surface for future years,” Mr Biswas said.
No one was injured as a result of the breach at the tailings dam and no environmental damage has been observed, according to Newcrest, which said it does not use mercury, cyanide or arsenic in the production process at the Cadia site, 25 kilometres south of Orange.
The mining giant on Thursday confirmed it will miss its full-year production guidance and will be unable to satisfy contracts for copper concentrate product because of the mine’s closure.
The government's Geoscience Australia Earthquakes site reported a 2.7-magnitude seismic event south-west of Cadia on Thursday, the day before Newcrest says it first noted cracks in the dam wall.
The mine was closed for three months last year because of earthquake damage.