Uranium mining in Australia occurs through underground and open pit hard-rock mining to expose the ore-body followed by radiometric testing on drilled and blasted masses of rock to ascertain average ore grade which then is milled to extract the uranium product from the mined ore. Australia is home to 31% of the world’s recoverable uranium. Australian uranium is exported and consists about one-quarter of its energy exports. Australia uses no nuclear power and depends on coal. The uranium mining industry is a billion dollar industry in Australian dollars with uranium booming as a result of global politics in the nuclear warfare front. Uranium stocks ASX trends have shifted more in the positive direction owing to the approval of a bill advancing the creation of a US national strategic uranium reserve in 2020. 

The prominent uranium mining companies in Australia include BHP Billiton based at Olympic Dam underground mine and ERA (Rio Tinto 68%) based at the Ranger open pit mine. In 2019, Australia produced 7790 tonnes of uranium and was ranked the world’s third best producer behind Kazakhstan and Canada. This article seeks to highlight uranium mining in Australia from what it is, where and how it is mined in Australia, its products and dust suppression in uranium mining from a Global Road Technology perspective. 

What is uranium and how was it discovered?

Natural uranium consists of two isotopes namely, uranium-238 and uranium-235. The fissile uranium 235 can be forced to undergo a chain reaction and split and release energy in the process. In a weapon the release of energy is uncontrolled and leads to a severe explosion. In a nuclear power plant the splitting rate of uranium-235 is controlled to limit energy release, which is used to produce high temperature steam to drive a turbine to generate electricity. The uranium 238 is fertile and tends to capture neutrons and undergoes radioactive decay to form plutonium-239 which is highly fissile and can be used in nuclear weapons or as reactor fuel. Ever since the discovery of radioactivity by French physicist Antoine-Henri Becquerel in 1896 and the follow-up discovery of radium an active uranium decay product by Marya Sklodowska famously known as Marie Curie there has been four major phases of uranium mining. These  have been driven by the need to substantiate uranium resources to meet the ability of rapidly growing demands which led to exploration and discovery of new deposits and specifically the major four phases have been:

  • the ‘radium’ phase from 1900 to 1940
  • the Cold War (military phase) from 1941 to the 1960s
  • the civilian phase from the 1970s to the mid-1990s 
  • the resurgence phase post 2003 

Uranium mining in Australia

Are environmental regulations, health and safety concerns or potential profit loss a concern right now?

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Australia’s uranium has been mined since 1954. Uranium deposits were mined and treated in Australia initially from the 1950s until 1971. Radium Hill in South Australia, Rum Jungle in the Northern Territory and Mary Kathleen in Queensland were the largest producers of uranium also known as yellowcake. Production came to a halt as result of exhaustion of ore reserves and non-availability of contracts. Uranium is pre-dominantly found in mineral deposits on its own, although it can be found in conjunction with certain types of vanadium deposits, or more rarely in certain gold fields and a few copper deposits. There are two primary uses of uranium:

  • As fuel in a nuclear power plant to produce electricity 
  • As an ingredient for nuclear weapons 

The uranium mining industry uses conventional mining and milling methods with other techniques such as solvent extraction and in situ leaching. Mining is performed through open cut or underground methods strictly depending on depth, size and other factors such as rivers or lakes. Milling starts with fine grinding, followed by either acid or alkaline leaching, solvent extraction, chemical precipitation and finally calcination to produce tri-uranium dioxide. Acid based leaching is more common owing to its quick and more complete extraction in addition to being cheaper whereas alkaline leaching is more suited to other ore types which may contain significant amount of limestone, the most common being surficial (carnotite or calcrete) type deposits. In situ leaching for uranium production is commonly suited for sandstone type of ore deposits. 

Uranium mining practices

In open cut mining, the overburden needs to be removed to expose the ore body, which is the part of the rock that contains economic concentrations of the uranium being sought. Drilling and blasting followed by removal of the disintegrated rock which is tested to distinguish between ore and waste to enable separate blasting of the two. Trucks are then used to transport the ore to stockpiles, primary crusher or to the waste dump accordingly. All these areas in in open cut mining of uranium generate dust which if not controlled can result in exposure of uranium dust to workers at the uranium mine. On the other hand, underground mining seeks to move as little waste rock as possible in sinking shafts or declines and digging tunnels such as drives and adits accessing ore body as full as possible although mining the actual ore body is generally more selective. The open stoping technique is used and it involves carefully drilling then blasting a large mass of rock so that the broken material can be removed. When the void is empty, it is then filled from above with waste rock and coarse tailing material with some cement and fly ash binder to maintain the integrity and structural support which enables extraction of the adjacent ore. As an example, BHP Billiton’s Olympic Dam underground mine performs its uranium mining using longhole open stoping, backfilled with cemented aggregate and waste rock after ore extraction. Practically, a block of ore is drilled from below and above, then blasted so that up to 100 000 tonnes is broken at once with each stope yielding up to 500 000 tonnes. Ore is then extracted from draw points at the bottom of the stope and taken to the underground primary crusher; the crushed ore is hoisted to the surface in skips and placed in a blending stockpile ready for processing. 

Controlling dust can reduce radiation risk

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Dust suppression in uranium mining is paramount especially during hard-rock mining, which is the most common form of uranium mining in Australia. The workplace health and safety of workers is of pivotal to the success of uranium mining in Australia therefore all uranium mining and milling operations are undertaken according to the Code of Practice and Safety Guide for Radiation Protection and Radioactive Waste Management in Mining and Mineral Processing. The code sets strict health standards for radiation and radon gas exposure for both workers and members of the public. Dust control is critical as gamma radiation is a hazard to those working close to high-grade ores which comes from radium in the ore as dust is the source of worker exposure to alpha radiation. Efficient dust control at the different stages of uranium mining activities is non-negotiable. Other complementary efforts include personal protective equipment in addition to dosimeters that have to be worn at all times to measure exposure to gamma radiation. The application of GRT dust control and suppression technologies can assist in protecting worker health and safety for conventional hazards and those exacerbated by the radioactive nature of these environments.

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REFERENCES 

Hore-Lacy. 2013. Uranium Mining, Processing, and Enrichment. Woodhead Publishing Limited. 

Hore-Lacy. 2012. Mining and milling of uranium. Woodhead Publishing Limited. 

Mudd, G.M. 2007. Radon releases from Australian uranium mining and milling projects: assessing the UNSCEAR approach. 

Mudd, G.M. 2014. The future of Yellowcake: A global assessment of uranium resources and mining. Science of the Total Environment. 472. 590-607. 

World Nuclear Association. 2020. Australia’s Uranium. Retrieved on 06/02/2021.