Rare Earths and the Balance Problem

Journal of Sustainable Metallurgy, Mar 2015

Maintaining the balance between the demand by the economic markets and the natural abundance of the rare-earth elements (REEs) in ores constitutes a major challenge for manufacturers of these elements. This is the so-called balance problem (or balancing problem). The ideal situation is a perfect match between the demand and (production) supply of REEs, so that there are no surpluses of any of the REEs. The balance problem implicates that the rare-earth industry has to either find new applications for REEs that are available in excess, or needs to search for substitutions for REEs that have limited availability and that are high in demand. Different solutions are proposed to solve the balance problem: diversification of REE resources, recycling and urban/landfill mining, substitution, reduced use and new high-volume applications. No single solution can solve the balance problem, but a combination of different strategies can. It is illustrated that the issue of thorium in REE ores is also directly related to the balance problem: presently, thorium is considered as radioactive waste, but this waste could be turned into a valuable resource by using thorium in a thorium-based nuclear fuel cycle.

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Rare Earths and the Balance Problem

J. Sustain. Metall. Rare Earths and the Balance Problem Koen Binnemans 0 1 Peter Tom Jones 0 1 0 P. T. Jones Department of Materials Engineering, KU Leuven , Kasteelpark Arenberg 44, P.O. Box 2450, 3001 Heverlee , Belgium 1 K. Binnemans (&) Department of Chemistry, KU Leuven , Celestijnenlaan 200F, P.O. Box 2404, 3001 Heverlee , Belgium Maintaining the balance between the demand by the economic markets and the natural abundance of the rare-earth elements (REEs) in ores constitutes a major challenge for manufacturers of these elements. This is the so-called balance problem (or balancing problem). The ideal situation is a perfect match between the demand and (production) supply of REEs, so that there are no surpluses of any of the REEs. The balance problem implicates that the rare-earth industry has to either find new applications for REEs that are available in excess, or needs to search for substitutions for REEs that have limited availability and that are high in demand. Different solutions are proposed to solve the balance problem: diversification of REE resources, recycling and urban/landfill mining, substitution, reduced use and new high-volume applications. No single solution can solve the balance problem, but a combination of different strategies can. It is illustrated that the issue of thorium in REE ores is also directly related to the balance problem: presently, thorium is considered as radioactive waste, but this waste could be turned into a valuable resource by using thorium in a thorium-based nuclear fuel cycle. Lanthanides; Permanent magnets; Rare earths; Recycling; Substitution; Thorium Introduction The global annual production of rare earths or rare-earth elements (REEs) is typically expressed in tonnes of rareearth oxides (REOs). At present, the estimated yearly total production of REOs is about 125,000 tonnes, although accurate production numbers are very difficult, if not impossible, to obtain. However, these total production numbers give no indication about the availability of the individual REEs. First of all, not the total amount of REE ores mined is of importance, but rather the total amount of REE concentrate separated in the different individual REEs. For some applications, such as mischmetal, no separated REEs are required. Secondly, the REEs are not present in equal amounts in the REE ores, due to differences in the natural abundances of these elements. The general trend in the natural abundance of the rare earths is that the elements become scarcer with increasing atomic number Z; as the abundances decrease over the lanthanide series, the heavy rare-earth elements (HREEs) are much less abundant than the light rare-earth elements (LREEs) [ 1 ]. Additionally, elements with an even atomic number Z are more abundant than elements with an odd atomic number (Oddo-Harkins rule). For example, cerium (Z = 58) is more abundant with respect to its neighbours lanthanum (Z = 57) and praseodymium (Z = 59). Cerium is the dominating rare-earth element in LREE-rich ores (bastna¨site and monazite), while yttrium is the main rare-earth element in HREE-rich ores (xenotime and ion-adsorption ores). The availability of the individual REEs is of concern for applications that require the use of pure REEs, such as phosphors and permanent magnets. If the REEs that are required for high-volume applications have a low natural abundance, the minimum quantity of REE concentrate that needs to be processed and separated is that quantity that will produce at least the amount of REEs required for these critical applications. As a consequence, some REEs will be produced in larger quantities than required by the REE market and, subsequently, these elements need to be stockpiled, which comes at a cost. The balance between the demand by the economic markets and the natural abundances of the REEs in ores is a major problem for manufacturers of these elements [ 2 ]. This is the so-called balance problem (or balancing problem) [ 3, 4 ]. The ideal situation is a perfect match between the demand and (production) supply of REEs, so that there are no surpluses of any of the individual REEs. This would result in the lowest market price for any of the REEs, because the production costs are shared by all rare-earth elements. Unfortunately, a market in balance is very difficult to achieve, because of changes in demand due to technological evolutions in applications. The result is a sometimes very high demand of a REE that is a minor constituent in the ore (such as dysprosium), while the demand of the major constituent (such as yttrium) is much lower. The size of the REE market is different in terms of value and volume. For instance, phosphors are a very important application of REEs in terms of value (1/3 of the REE market), but they are a rather modest application in terms of volume (about 7 %). The balance problem is related to the volumes of the individual REEs consumed. For the REE industry the balance problem i (...truncated)


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Koen Binnemans, Peter Tom Jones. Rare Earths and the Balance Problem, Journal of Sustainable Metallurgy, 2015, pp. 29-38, Volume 1, Issue 1, DOI: 10.1007/s40831-014-0005-1