Tank failure investigations continue

17 December 2013

An independent expert is looking into the cause of a leaching tank rupture at the Ranger uranium mine in Australia. The incident followed a similar failure at Rössing in Namibia, which is also under investigation.

One of several leaching tanks at Ranger - ruptured on 7 December releasing a mixture of slurry containing mud, water, ore and acid. The plant's containment systems - including barriers and channelling - kept all the slurry mixture within the mine's processing area, Energy Resources of Australia (ERA) reported.

The company has now appointed an independent expert to examine the root cause of the failure. That person will also review processing infrastructure at the site. ERA's investigation will run in parallel with a joint investigation being carried out by a government-appointed taskforce. 

The processing of uranium ore involves it being ground and put through a sulfuric acid leach to recover the uranium. During this process, ore slurry is pumped into several leaching tanks into where sulfuric acid and pyrolusite (a manganese-based oxidant) are added to dissolve the uranium in the ore.

Processing operations have been suspended at Ranger. ERA - majority owned by Rio Tinto - is assessing the full impact of the incident on operations, including how long processing operations will be offline and what repairs are required. A structural engineer has informed the company that the support structure surrounding the remaining leach tanks, and the tanks themselves, are structurally sound.

ERA chief executive Andrea Sutton commented, "It's important that we identify the root cause of the incident so that we can prevent anything similar happening in the future."

Rössing rupture

The tank failure at Ranger came four days after a similar tank ruptured at the Rössing mine in Namibia, in which Rio Tinto also holds a majority stake.

On 3 December, one of twelve leach tanks at Rössing failed, but again the spilled slurry was channelled by existing engineered trenches into an overflow sump in the plant's containment system.

Milling operations at the plant were suspended and will restart once restoration work is completed. Production in other areas of the mine continues. The cost of repairs and restart schedule are being assessed.

The mine said that it is working with the relevant regulatory authorities in Namibia in the management of the incident.

Neither the Ranger or Rössing incident resulted in any injuries nor was there any environmental impact to the surrounding areas.

Researched and written
by World Nuclear News