World production in 2013 of rare earth oxides was 110,000 tonne, with main production from China of 100,000 tonne, USA at 4,000 tonne and Australia at 2,000 tonne, mainly from the Mount Weld deposit in Western Australia. World resources are dominated by deposits rich in the minerals bastnasite, and monazite., with the largest resources of these minerals in China and the USA.
Rare earths-bearing minerals monazite and xenotime occur in many of Australia’s heavy mineral sand deposits and, up until the mid-1990s, monazite was produced from them and exported, mainly to Europe. A brief overview of these activities is given by Hoatson et.al (2011). Currently, REE occurring in heavy mineral sand resources make up around 6% of Australia’s inventory of REE resources.
Rare earths were named by Johann Gadolin in 1794 for a group of chemically similar, metallic elements with atomic numbers 57 through to 71. In order, these are lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). These elements are commonly known as the lanthanide series and are divided into light rare earths (lanthanum–gadolinium) and heavy rare earths (terbium–lutetium). Scandium (Sc, atomic number 21), yttrium (Y, atomic number 39) and thorium (Th, atomic number 90) are also generally included in the rare earth group because of their similar chemical properties.
Currently, South Australia has no rare earth production but an estimated 1500 t of rare earths comprising the oxides of scandium (3%), yttrium (16%), lanthanum (38%), cerium (24%), praseodymium (0.7%), neodymium (1.8%), samarium (0.2%), europium (0.07%), gadolinium (0.4%), terbium (0.5%), dysprosium (3.3%), holmium (0.7%), erbium (3.8%), thulium (0.7%), ytterbium (6.5%) and lutetium (0.6%) remain in uranium tailings at Port Pirie where davidite concentrates, produced at the Radium Hill Mine between 1954 and 1961, were treated.
This purpose-built Port Pirie treatment plant used an acid leach and ion exchange process to produce yellowcake from concentrated ore railed from the Radium Hill mine from 1955–62. Following decommissioning of the site in 1962, a number of smaller concerns have used the property for various operations including the extraction of Rare Earth Elements (REE). All original infrastructure related to the site was demolished in 2006.
Some South Australian Iron oxide-Copper-Gold (IOCG)-type deposits carry REE below economic levels. Future discoveries of IOCG-type deposits may carry elevated REE values. Exploration drilling at Ketchowla has identified elevated values for REE associated with secondary iron and manganese oxides.
Australia is a major producer of mineral sands containing titanium minerals and zircon. A valuable by-product of this is monazite containing thorium, which is radioactive.
Monazite is a minor constituent of many mineral sands deposits. Appropriate occupational health provisions ensure safety in handling materials containing thorium.
Heavy Minerals Mineral sands contain suites of minerals with high specific gravity known as ‘heavy minerals’.
Mineral sands are mined by surface mining methods including open cut mining, suction dredging and hydraulic mining. The first stage of the mining process is to remove all timber and topsoil from the mine site. The topsoil is stockpiled for later rehabilitation of the site after mining has been completed. Various methods which include magnetic, gravity and electrostatic separation as well as chemical processes, are then used to separate the sands into individual mineral species. The ore is put through a screening plant which breaks it down into individual grains. The heavy mineral grains are 0.05 to 0.3mm in size, material greater than 2mm is dumped back in the mining area.
Rutile, ilmenite, leucoxene (an alteration product of ilmenite) are used predominantly in the production of titanium dioxide (TiO2) pigment. The titanium-bearing minerals rutile and leucoxene are sometimes blended to produce HiTi (High grade titanium with a TiO2 content of 70% to 95%) which is used as a feedstock to produce titanium dioxide, make titanium metals for the aerospace industry and in the manufacture of welding rods. Less than 4% of total titanium mineral production, typically rutile, is used in making titanium sponge metal. Zircon is used as an opacifier for glazes on ceramic tiles, in refractories and for the foundry industry. Recently there has been renewed interest in monazite as a source of thorium for possible use to generate electricity in thorium nuclear reactors. Televisions – for luminescence and colour
Electronics – for a variety of components including high-performance magnets (cerium)
Robots – electric stepping motors
Computers – monitor luminescence, electronic components and bubble memory systems
Lighting – energy efficient lanthanum lamps
Medicine – X-ray screens, fibre optics, pain-killing elements
Chemistry – catalysts
Ceramics – pigment.
Products from monazite are also used in metallurgy, flints, ferro-alloys, glass polishing, jewellery, fuel cells, refractories, lamp mantles (thorium) and welding electrodes.
Yttrium from xenotime has been used in the most effective superconductors.
The occupational health issue of specific relevance to the mineral sands industry is radiation. Western Australian mineral sands deposits contain up to 10% heavy minerals, of which 1-3% is monazite. This in turn typically contains 5-7% of radioactive thorium and 0.1 – 0.3% of uranium, which is barely radioactive. In ore, or general heavy mineral concentrate, the radiation levels are too low for radioactive classifications.
However, when the radioactive material is concentrated in the process of separation and production of monazite the radiation levels are increased, creating the need for special controls to protect some “designated” employees in dry separation plants. In the past, occupational exposure to radiation levels of 50 mSv/yr, then the limit, were not uncommon. Dust control is the most important objective in radiation safety for the titanium minerals industry. The most significant potential radiation problem is inhaled thorium in mineral sands dust.
This contrasts with other industries where the focus for radiation protection has been direct gamma radiation from materials in rock. Exposure to gamma radiation still needs to be controlled in the mineral sands industry, due principally to uranium and thorium in zircon. However, safety programs are targeting alpha radiation arising from airborne dust which may be inhaled.
Minister for Resources and Northern Australia Matt Canavan says Australia could become a major global supplier of minerals critical to 21st Century technologies. Releasing a report on Friday from Geoscience Australia – Critical Minerals in Australia – Minister Canavan said Australia was well placed to produce significant extra wealth from its extensive mineral resources, and world-class mining expertise.
Commissioned by Geoscience Australia in collaboration with RMIT University and Monash University, the report analyses the current state of critical minerals in Australia and highlights key areas for future research.
To be classified as “critical”, a mineral must be both economically important to society and vulnerable to supply disruption and many critical minerals are irreplaceable components of technological and industrial advancement.
The report found there was insufficient knowledge of critical minerals in Australian deposits and their behaviour during metallurgical processing, few dedicated geological studies into critical minerals and there was a need for new mining technology and services to economically extract critical minerals The critical mineral Indium is a by-product of zinc yet, despite Australia being a major producer of zinc there is no known current domestic production of refined indium even though some smelters may have production capability.
“Other critical minerals, which can be extracted from zinc concentrates, include gallium, germanium and cadmium,” the report said. “A similar situation exists for copper concentrates and associated critical minerals (e.g. tellurium, indium, selenium).”
Two areas in North West Queensland were listed in the report Hammer’s Kalman Resource and Chinova’s Merlin which contain molybdenum and rhenium, both used in the steel industry. Merlin is inactive since Chinova shut down nearby Osborne mine in 2014 but is believed to contain 10 per cent of the world’s rhenium. Senator Canavan said Australian could leverage leadership in the global mineral resource industry to grow our critical minerals sector and Australia was one of the world’s top five producers of critical minerals such as antimony, cobalt, lithium and rare earths.
“The growing list of new and emerging technologies using critical minerals includes advanced manufacturing and health applications, rechargeable batteries, renewable energy systems and electric cars,” Senator Canavan said.
Minister Canavan said the Australian Government is committed to ensuring Australia reaches its potential as a global supplier of critical minerals. “The Australia’s National Resources Statement released in February 2019 outlined the development of a national strategy through the Council of Australian Governments Energy Council to harness the emerging opportunities offered by the critical minerals sector,” Senator Canavan said. “We also announced critical minerals projects would be prioritised in the latest industry funding round, which closes on March 28.
Senator Canavan said they were engaging with key trading partners on critical minerals. “Late last year, I signed a Letter of Intent with my counterpart from the United States agreeing to collaborate on joint activities in the area of critical minerals,” he said. The Critical Minerals in Australia: A Review of Opportunities and Research Needs report is available from ga.gov.au/criticalminerals .
The Australian Government has released the latest Australia’s Identified Mineral Resources (AIMR) report.
Speaking at the Prospectors and Developers Association of Canada (PDAC) Convention in Toronto, Minister for Resources and Northern Australia, Matt Canavan, announced that the new statistics show Australia has the world’s largest identified resources of nine major mineral commodities.AIMR 2017 includes assessments of reserves and resources at operating mines and other deposits, evaluations of long-term trends for major commodities, and comparative world rankings for mineral resources.
It shows that Australia’s robust mining industry remains a world leader, keeping Australia as an attractive investment destination. We are in the top five in the world as a producer of 20 out of 34 important commodities, including gold, bauxite, iron ore, rare earths, mineral sands, zinc, lead and coal. These commodities are essential for maintaining and powering our modern lifestyles and for building a high-tech future.In 2016, Australia’s mineral exports (excluding petroleum) amounted to a value of more than $151 billion. This was almost 46 per cent of the value of all exported goods and services. In the 2016-17 financial year, mining accounted for 7.4 per cent of Australia’s gross domestic product.As at December 2016, Australia had the highest Economic Demonstrated Resources in the world for gold, iron ore, lead, nickel, rutile, tantalum, uranium, zinc and zircon. In 2017, Australia had 301 operating mines.