Newcrest Mining has contained a breakthrough of tailings material at the Cadia gold mine in New South Wales after it was forced to suspend operations at the site last Friday.
The company yesterday reported that a “limited breakthrough” of tailings material was identified at the Cadia northern tailings dam embankment.
With the breakthrough contained within the southern tailings dam, Newcrest is monitoring the impact of the incident and has observed no environmental damage. No injuries have resulted from the event, the company added.
Newcrest explained that an area of the embankment slumped late Friday following the identification of cracks earlier that day during an inspection.
When Newcrest noticed the cracks, the Cadia team engaged an independent geotechnical consultant to assist its geotechnical engineers with an inspection and preliminary assessment of the embankment.
Newcrest has secured the area around the tailings dam and implemented a geotechnical monitoring system, involving radar and cameras, to allow real-time assessment of ground movement of the dam wall. The miner immediately notified NSW regulators of the incident and suspended activities at the mine.
“Whilst it is too early in the evaluation and recovery process for Newcrest to provide an indication of the extent to which FY18 production, capital and cost guidance will be impacted, this event will adversely impact guidance for FY18 given the contribution of Cadia to the overall outcomes of Newcrest. Further updates will be provided to the market when available,” Newcrest said in an ASX announcement.
The tailings material is a slurry of finely ground rock, water and a low level of benign processing reagents.
Cadia uses a gravity circuit to recover gold, with the remaining gold and copper reporting to a concentrate which is exported to copper smelters.
The mine does not use a chemical reduction process to recover gold – therefore, the gold extraction process does not involve the use of substances such as mercury, cyanide and arsenic.
Cadia is 25km from Orange in central NSW and 250km west of Sydney.