Thorium Properties and Uses
Thorium is a naturally occurring slightly radioactive metal, three to five times more abundant than uranium. The most common source of thorium is a rare earth phosphate mineral, monazite.
Thorium oxide (ThO2) has one of the highest melting points of all oxides at 3300°C and has been used in light bulb elements, lantern mantles, arc-light lamps and welding electrodes as well as in heat resistant ceramics.
Currently there is no large scale demand for thorium resources. Thorium can be used also as a nuclear fuel although there are no commercial scale thorium fuelled nuclear reactors currently operating in the world. Several reactor concepts based on thorium fuel cycles are under consideration, but a considerable amount of development work is required before it can be commercialised. Some of the countries currently involved in researching development of thorium fuelled reactors, either as a stand-alone thorium reactor or in existing uranium fuelled reactors, include India, China, Norway, and France.
A commercial scale thorium-fuelled nuclear plant, the Fort St Vrain reactor in the USA, operated between 1976 and 1989 and used 25 tonnes of thorium as fuel for the reactor. Research into thorium-fuelled nuclear reactors is continuing, particularly in countries with abundant thorium but little uranium resources. Thorium as a nuclear fuel is considered to have some advantages over the uranium fuel cycle because its use results in smaller volumes of nuclear waste.
Thorium Production and Exports
There is no production of thorium in Australia, but it is present in monazite currently being mined with other minerals in heavy mineral beach sand deposits.
Historically, Australia has exported large quantities of monazite from mineral sands mined in Western Australia, New South Wales and Queensland for the extraction of both thorium and rare earths resulting in the export of 265 kilotonne of monazite between 1952 and 1995. However, since production ceased in 1995 it is believed no significant quantities of thorium, or materials containing thorium, have been exported or imported by Australia.
In current mineral sand operations, the monazite is returned to mine site and dispersed as stipulated in mining conditions.
Thorium Resources and World Ranking
The Organisation for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA) and International Atomic Energy Agency (IAEA) has compiled estimates of thorium resources on a country-by-country basis although the OECD/NEA report notes that the estimates are subjective as a result of the variability in the quality of the data, a lot of which is old and incomplete. Table 1 has been derived by Geoscience Australia from information presented in the OECD/NEA analysis. The total identified resources refer to Reasonably Assured Resources (RAR) plus inferred resources of thorium recoverable at less that US$80 a kilogram.
|Country||Total Identified Thorium Resources |
(Reasonably Assured + Inferred Resources)*
(’000 t Th) <USD 80/kg Th
|United States of America||400|
Sources: Data for Australia compiled by Geoscience Australia; estimates for all other countries are from: OECD/NEA and IAEA, 2009: Resources, Production and Demand. OECD/NEA and IAEA. *See definitions of resource categories in Australian Mines Atlas.
Australia’s thorium resources are summarised in Australia’s Identified Mineral Resources.
Information on Australia’s thorium resources is also accessible via the Australian Mines Atlas.
There has been no widespread exploration for thorium in Australia although it has been a significant component of some deposits being explored for other commodities. Thorium is present in the Nolans Bore deposit in the Northern Territory and in the Toongi intrusives complex in New South Wales. Heavy mineral concentrations within the King Leopold Sandstone and the Warton Sandstone in Western Australia, which constitute the Durack Range uranium project, also contain up to two per cent thorium in the heavy mineral concentrate.
Geoscience Australia Programs
During 2007-08 Geoscience Australia carried out a small thorium project to acquire:
- an improved understanding of the status and distribution of Australia's thorium resources for use in the determination of government policy and industry investment decisions
- a better understanding of the geochemistry of the thorium cycle in the Earth's crust
- development of recommendations outlining whether an expanded Thorium Project is required.
This project reviewed Australia's thorium resources and the geochemical processes controlling the distribution of the element in the earth's crust. Results of the projects review have been published in A Review of the Geochemical Processes Controlling the Distribution of Thorium in the Earth's Crust and Australia's Thorium Resources.
Topic contact: firstname.lastname@example.org Last updated: June 25, 2012