Monday, 28 November 2011

NTN summary of Lynas radioactive tailings seepage at Mt Weld

Rare Earth Ores and Radiation Risks at
Lynas Corporation’s Mt Weld Operation
Lee Bell
November 2011

The National Toxics Network (NTN) has been investigating the potential of radioactive contamination arising from the Lynas’ rare earth concentrate plant at Mt Weld, near Laverton Western Australian. NTN is concerned a regulatory loophole is being utilised to improperly transport radioactive materials through WA suburbs to be shipped to Malaysia.

According to environmental and mining authorities in Western Australia, the waste slurry generated from the chemical processing and flotation of the rare earth ores at Lynas Corporation’s Mt Weld concentrator plant is radioactive. The radiation is primarily due to the thorium and uranium content of the ore. 

The tailings from the ore concentrator have also been deemed radioactive by the state Department of Mining and Petroleum.

NTN is extremely concerned that the concentrate will soon be transported through residential suburbs as if it were not a radioactive substance, with no identifying signage, despite being subject to a radiation management plan that has not been released for public consultation. The public and workers have a right to know about the radiation risks to which they will be exposed.
For a number of year Lynas has mined and stored stockpiles of rare earth ores (REO) at the Mt Weld mine site and graded these stockpiles according to purity and other factors. The stockpiled ore is then shipped 1.5 km to the concentrator plant where impurities are removed through chemical and flotation processes. Two major streams of material then leave the concentrator plant. 

Firstly, the product is a lanthanum oxide concentrate (which also contains a range of other rare earths) and a waste stream which is a slurry of water and process liquors contaminated with 15.8% solids including the uranium and thorium with a pH of 10.5-10.8. Secondly, the waste is then piped to large tailings ponds where the liquid fraction can evaporate over time. This has the effect of concentrating the solid fraction of radioactive materials within the tailings pond residues. This concentrating factor has not been assessed by authorities and could result in radioactivity levels many times higher than claimed in the proponent’s reports especially towards the end of the mine life. As the ponds dry out airborne dust containing radioactive particles will become a major management problem for decades to come.

Government documents have become available which indicate that Lynas Corporation failed to construct its tailings ponds according to the engineering conditions laid down in the environmental operating licence issued by the WA Department of Environment and Conservation. 

As a result Lynas has been ordered by the DEC to rebuild a small section of their tailings pond and line it with High Density Polyethylene (HDPE) as an interim measure. If Lynas had received government approvals and used the initial tailings ponds they constructed, they would have leaked at an estimated 186, 000 litres per day or over 67 million litres per annum of radioactive leachate.

The DEC Environmental Assessment Report for the concentrator plant makes it clear that Lynas Corporation failed to meet the regulatory controls and conditions put in place to prevent environmental contamination from processing rare earth ore tailings production. It also raises considerable doubt about their ability to meet waste disposal regulations and environmental protection requirements in other jurisdictions such as Malaysia. 

Radioactive tailings leakage – a licence to pollute.
The ‘tailings’ or waste material from the processing of rare earth ores at Mt Weld into a concentrate, contains 500ppm ThO2 (Thorium Oxide) and 30ppm U3O8 (Uranium Oxide). The calculated radiation specific activity from this combination is 1.80 Bq/g for the Thorium and 0.32 Bq/g for the Uranium which totals 2.12 Bq/g. This is more than twice the threshold radioactivity level set by the Department of Mining and Petroleum for classification as radioactive tailings (‘radioactive’ classification is in excess of 1.0 Bq/g). This regulatory criterion occurs under the Western Australian Mines Safety and Inspection Regulations 1995.

The Tailings Storage Facility (TSF) is a 17.5 hectare paddock style impoundment constructed in two stages. The first stage was intended to take the first two years of waste followed by stage two which would see the banks raised to accommodate the future production waste.

A review of the integrity of the tailings ponds by Lynas engineering consultants Knight Piesold in 20091 found alarming evidence that the radioactive waste material would have been able to leak at the rate of 186,000 litres per day if the ponds had started to accept tailings. WA authorities ordered Lynas to fix their tailings facility after finding that the construction was grossly inadequate and a small tailings pond has now been lined with HDPE plastics to act as an interim waste storage pond. The remainder of the large tailing pond will now have to be re-engineered with HDPE over time.

However, even the new lined tailings facility is estimated to leak at the rate of up to 14,000 litres per day according to the Department of Environment and Conservation.2 

Far from their claims of being a clean, green industry Lynas Corporation are prepared to allow the leakage of over 5 million litres of radioactive tailings every year at the site of their concentrator plant. The concentrator plant has been operating since May 2011 and 2.5 million litres of contaminated tailings have already leaked from the facility if the Department of Environment and Conservations predictions are correct. No monitoring data from the site has been released to the public as yet.

Contradictory regulations on Transport
Lynas confirm in their Radiation Management Plan that because their “ore, concentrate and tailings contain elevated concentrators of natural thorium and uranium personal annual radiation exposures at the Mt Weld operation were predicted to be above the annual public dose limit of 1mSv per year”.3

In spite of the clear admission by Lynas Corporation that their ore, tailings and concentrate are sufficiently radioactive to exceed the annual public dose limit, they failed to take measures to sufficiently engineer their tailings pond resulting in potentially massive leakage of the radioactive waste. 

At this stage there are no clear indications as to how the concentrated tailings will be managed at the end of the ponds life or the mine’s decommissioning. Given that the ponds will be built in a hot, arid zone with little rainfall, the ponds can be expected to dry out and generate dust with radioactive particles and other heavy metals. 

Notably, Malaysia also classifies waste or radioactive materials as ‘radioactive’ when the specific radioactivity level exceeds 1.0 Bq/g. This is the reason why Lynas Corporations ‘product’ or rare earth concentrate will be regulated as radioactive material for transportation purposes, from the moment it lands in Malaysia.

Lynas Corporation have relied on an exemption loophole in the Western Australian transport regulations to allow their concentrate to be shipped from Mt Weld to Fremantle Port (nearly 1000km) without it being classified as radioactive material. The loophole allows the concentrate to be transported without Dangerous Goods classification or ‘radioactive material’ classification due to an exemption clause in the Radiation Safety (Transport of Radioactive Substances) Regulations, WA, 2002 which allows up to 10 Bq/g of specific radioactivity if the product is not destined for production to extract the radioactive elements (uranium and thorium) or if the material is not subject to chemical processing.  

This is despite the fact that the Thorium levels are much higher in the concentrate (approx 1700 ppm) giving it a specific radioactivity level between 3.5 and 8 Bq/g4. So even though the concentrate exceeds the level at which tailings are classified radioactive by up to eight times, and exceeds the Malaysian transport regulations by up to eight times it will not be classified ‘radioactive’ for transport purposes in Western Australia thereby disguising its true nature to the public

There will be no signage or placarding on the trucks carrying the concentrate denoting its radioactive nature. This is critical for emergency workers to make rapid decisions in the event of an accident or spill of the concentrate on public roads or at the port.

Lynas argue that the Radiation Safety (Transport of Radioactive Substances) Regulations, WA, 2002 and the ARPANSA Safe Transport of Radioactive Material Code of Practice (STRM, 2007) applies only to materials that are not chemically processed or intended for the extraction of the radionuclides. However, the processing of concentrate at Mt Weld involves the use of at least 5 chemicals which contradicts their claim that they are subject to an exemption from the transport regulations. 

Indeed Lynas Corporation’s Environmental Impact Assessment5 documents for their rare earth processing plant in Malaysia state; “The Advanced Materials Project involves processing lanthanide concentrate from Mt Weld in Western Australia, at a processing site that uses chemical treatment processes.”

Further it can be argued that the Lynas Advanced Materials Plant (LAMP) in Malaysia will process the material to extract the radioactive elements uranium and thorium as well as other impurities. The impurities will then be dumped as part of the LAMP waste stream in Malaysia. As such the exemption from radioactive transport requirements in WA appears to be based on proponent assurances rather than sound science.
Contact : Lee  Bell BA MA (ESD)


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