Which Elements are They?
The rare earths are a moderately abundant group of 17 elements comprising the 15 lanthanides, scandium, and yttrium. The lanthanides comprise a group of 15 elements with atomic numbers 57 through 71 as shown in the periodic table below. In order of atomic number (atomic symbol) the lanthanides 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).
The rare earths can be classified as being either a “light-group rare earth element” (LREE) or a “heavy-group rare earth element” (HREE). The definition of LREE and HREE, as below, is definitive and is as used by the U.S. Government’s Department of the Interior, the U.S. Geological Survey and the U.S. Department of Energy, including the National Laboratories. A classification that includes “middle-group rare earth elements”, sometimes used to identify the elements with atomic numbers 63 to 68, inclusive, is not considered valid.
The LREE group covers the elements from lanthanum, atomic number 57, through to gadolinium, atomic number 64. The HREE group covers the elements from terbium, atomic number 65, through to lutetium, atomic number 71. Yttrium, atomic number 39, is included in the HREE group based on its similar ionic radius and similar chemical properties. Scandium is also trivalent; however, its other properties are not similar enough to classify it as either a LREE or HREE.
It is the variation in electronic configuration between the individual rare earths that is critical to the properties that the rare-earth elements exhibit and how they interact with other elements and compounds.
The Common Rare Earths-Bearing Minerals
In rock-forming minerals, rare earths typically occur in compounds as trivalent cations in carbonates, oxides, phosphates, and silicates. The most common minerals are shown in the list below which is far from comprehensive.
|Rhabdophane||(Nd,Ce,La)(PO4) • H2O|
Historical Production of Rare Earths
Early production of rare earths oxides was derived mainly from monazite-bearing-placers, predominantly from South Africa, India and Brazil, from which production in the period from the mid-1950s to the early-2000s rarely exceeding 10,000 tonnes per annum. In 1965 hard rock production from the Mountain Pass deposit in the USA expanded and continued at around 20,000 tonnes per annum until the early-2000s. From 1985 production from China grew rapidly and by the early-2000s had almost total domination of world production.
In addition to being the world’s largest producer of rare earth materials, China is also the dominant consumer followed by Japan and the United States.
By 2010 China controlled about 95% of the world’s rare earth production and prices for many rare earth oxides but prices had risen over 500% in just a few years. This situation cause alarm bells to ring worldwide, with the threat of supply shortages and cost escalation to rare earth consumers and miners throughout the world. Mining and exploration companies in the United States, Australia, Canada and other countries began to re-evaluate old rare earth prospects and explore for new ones.
The higher rare earths prices also caused manufacturers to do three things:
- seek ways to reduce the amount of rare earth elements needed to produce each of their products;
- seek alternative materials to use in place of rare earth elements; and,
- develop alternative products that do not require rare earth elements.
Despite these efforts, the demand for more products manufactured with rare earth elements has increased resulting in higher consumption.
Chinese companies have been actively purchasing rare earth resources in other countries. In 2009, China Non-Ferrous Metal Mining Company bought a majority stake in Lynas Corporation, an Australian company that currently has one of the highest outputs of rare earth elements outside of China.
Rare earth project exploration and evaluation are underway in Australia, Brazil, Canada, China, Finland, Greenland, India, Kyrgyzstan, Madagascar, Malawi, Mozambique, South Africa, Sweden, Tanzania, Turkey, and Vietnam, but news flow has noticeably reduced since 2015 and a number of these projects are currently mothballed.
The United States Geological Survey estimates that although China is the world-leader in rare earth production they only control about 50% of the world’s reserves. This provides an opportunity for other countries to become important producers.
Hastings’ Target Rare Earths
At Yangibana, the Company is developing an operation that will produce a mixed rare earths carbonate (MREC) product that will be transported and processed away from site. The majority of the value of the MREC lies in its neodymium and praseodymium content, with lesser value derived from dysprosium and terbium content.
At Brockman, the Company is evaluating an operation that would produce both rare metals (potentially niobium, tantalum, zirconium) and rare earths. The main rare earths of interest at Brockman are dysprosium and yttrium. Brockman is some way from development at this stage with Company concentrating its efforts at Yangibana.