Namib Times: Rio Tinto's Rössing uranium mine shuts operations after 'catastrophic leak’

Publish Date:
6th December 2013

read on Namib Times website

By Jade McClune & Marshallino Beukes

All milling operations at Rössing Uranium Mine ground to an immediate halt after “a catastrophic structural failure” at one of twelve leach tanks in the processing plant on Tuesday.

The incident triggered a veritable crisis, reinforcing widespread fears of a radioactive leak.

Sources at the mine told the Namib Times on Tuesday that they had heard some “kind of explosion”.

The mine has since confirmed that a leak was detected near one of the leach tanks and said there was “a very serious incident”, but did not mention any explosion.

A Red Banner Health and Safety Alert was sent out to all employees of the mine on Wednesday, confirming that there had been a “leach tank failure” at around 18:30 on Tuesday, 3 December.

The actual outcome of the incident was described as “serious” and the “maximum reasonable outcome: critical”.

In a circular to staff on Wednesday, Mr Ben De Vries, General Manager of Operations, said “This is obviously a very serious incident which is currently under investigation. I can assure you that we are applying a rigorous and structured approach to determine the cause of this failure and ensure that we safely return the plant to normal operations as soon as possible.”

“At the moment the milling operation had been stopped, but is expected to restart once the failed tank has been isolated from the production process. Production in the other areas of the mine has not been affected and continues as usual, De Vries told the newspaper yesterday.

How it happened

In a statement released on Wednesday, the company said that a“leak was detected on [Number] 6/1 Leach Tank shell and as a result it was decided to pump out the tank for fixing. Two operators went on top to close 6/1 leach tank launder and opened up 5/1 leach tank launder to re-route the slurry. The other four operators were below (close to 2/1 leach tank) fitting the water pipe used for flushing the pump out system… located next to 6/1 leach tank. During this time 6/1 leach tank experienced a catastrophic structural failure on the shell, while one of the sectional operators was on top of the tank… the operator on top of 6/1 leach tank was swayed onto the hand rail. He sustained minor bruises to his left lower arm and knee.”

“Spilled slime”

Referring to the unspecified leaked material in question only as “the spilled slime”, the company said on Thursday that it was “channeled in trenches and contained in a holding tank.” Mr De Vries reasoned that there was “no environmental impact” and said that “the spilled slime is to be recycled in the processing plant.”

Leach tanks are used in a key stage in the process of extracting uranium oxide from the ore and involves processing the milled ore in large tanks containing acid-sulphuric solution, causing the valuable minerals leach from the ore into the solution.

De Vries explained that the leaching process produces “a pulp, containing suspended sand and slime, which is washed to remove traces of uranium-bearing solution”, but did not say whether the “spilled slime” is radioactive. The mine did not yet specify the cause of the structural failure, the extent of the leak, or the radiological risk, but said that the area was evacuated and demarcated and that all team members were accounted for.

An investigation and assessment of the extent of the damage is underway and a “return to operation plan” is being developed, pending the preiminary investigation.

Radiation Protection Agency steps in

By 21:15 on Wednesday night the Director of National Radiation Protection Agency (NRPA) had not yet been informed of the “structural failure” at the mine on Tuesday.

In response to questions from the Namib Times, NRPA Director Alex Tibinyane said: “This is news to me and (I) cannot answer your questions, but thank you for sharing this with me. We will follow it up.”

Although there is no specified time frame, the Atomic Energy and Radiation Protection Act of 2005, stipulates that any license holder is obliged to “within a reasonable time, notify the Director-General of any accident which has occurred in any undertaking operated by him or her and of any loss of life or serious personal injury caused by any such accident.”

According to the Act of 2005, any person who does anything “that causes the uncontrolled or unregulated emission of radiation which is likely to cause loss of life, significant bodily harm or serious damage to the environment or the property of any person, is guilty of an offence and is liable on conviction to a fine not exceeding N$200 000 or to imprisonment for a period not exceeding 10 years, or both…”