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RARE EARTH INDUSTRY OVERVIEW

Joseph Gambogi

National Minerals Information Center, U.S. Geological Survey, Reston, Virginia, USA

Abstract

The rare earth elements (REEs) are a group of moderately abundant elements comprising the 15 lanthanides, scandium (Sc), and yttrium (Y). Most REE production has been from deposits where specific minerals (usually bastnaesite, loparite, monazite, and xenotime) or ores such as ion-adsorption clays are amenable to known industrial-scale physical and chemical separation techniques. The rare earth industry is complex and evolving with changing geographic sources of supply and shifting demand for specific REEs. Global mine production tripled from 2010 to 2022. New sources of supply have changed trade patterns for mineral concentrates, metals, and compounds. While China has remained the largest global producer, its imports have increased from 12 thousand metric tons (KMt) in 2010 to over 126 KMt in 2021. A few mine producers have emerged as established sources of supply, and interests in developing new alternative sources of supply are ongoing. Several factors have contributed to price volatility for rare earth materials including political tensions, shifts in demand patterns, and supply disruptions. Prices for rare earth materials peaked in 2011 following changes in China's export quotas and political tensions between China and Japan. In subsequent years, prices for most rare earths decreased significantly but were influenced by rising or falling demand for specific applications such as permanent magnets and phosphors.

1.1. Introduction

Despite their name, the rare earth elements (REEs) are a group of moderately abundant elements comprising the 15 lanthanides, scandium (Sc), and yttrium (Y). The lanthanides are the elements with atomic numbers 57 through 71, in the following order: 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).

Excluding scandium, REEs can be classified as either light rare earth elements (LREEs) or heavy rare earth elements (HREEs). The LREEs include the lanthanide elements from atomic number 57 (La) through atomic number 64 (Gd), and the HREEs include the lanthanide elements from atomic number 65 (Tb) through atomic number 71 (Lu). The division is based on the LREEs having unpaired electrons in the 4f electron shell and HREEs having paired electrons in the 4f electron shell. Yttrium is chemically similar to the HREE lanthanides and commonly occurs in the same minerals as a result of its similar ionic radius. Consequently, yttrium is considered an HREE even though it is not part of the lanthanide series (Rare Earth Industry Association, n.d.).

In rock-forming minerals, rare earths typically occur in compounds as trivalent cations in carbonates, oxides, phosphates, and silicates (Mason and Moore, 1982, p. 46). Because REEs often share a divalent or trivalent charge and similar ionic radii, they are found together in a complex and diverse suite of minerals. Hundreds of REE-bearing minerals have been identified in a variety of depositional environments (Van Gosen, et al., 2017).

1.2. Production

Most REE production has been from deposits where specific minerals (usually bastnaesite, loparite, monazite, xenotime) or ores such as ion-adsorption clays are amenable to known industrial-scale physical and chemical separation techniques.

Figure 1.1 Global estimated rare earth mine production (metric tons (Mt) of rare-earth-oxide equivalent).

Source: U.S. Geological Survey National Minerals Information Center, https://www.usgs.gov/centers/national-minerals-information-center/rare-earths-statistics-and-information./United States Global Change /Public Domain.

LREEs have been produced predominantly from bastnaesite and monazite found in carbonatite and placer deposits, while production of HREEs has largely been from ion-adsorption clays in Southern China and Burma (Myanmar). Sources of rare earths are evolving with changes in end uses, mining and processing technologies, and environmental concerns. Extensive research is ongoing to recycle REEs and recover REEs as byproducts of mine tailings and intermediate process streams.

Global production tripled during the period from 2010 to 2022 exceeding 300 thousand metric tons (KMt) of rare-earth-oxide (REO) equivalent in 2022. Since the 1980s, China has consistently led global production. Owing to increased production from Australia, Burma (Myanmar), and the United States, China's contribution to the total has fallen from 90% in 2010 to about 70% in 2022. Concurrent with increased production outside of China, China increased its mine production quota to 210 KMt in 2022 from 89 KMt in 2010 (Figure 1.1).

1.2.1. Australia

Australia has significant production, reserves, and resources of REEs. Prior to the commissioning of the Mount Weld mining operations in 2011 by Lynas Corp., Australia's REE mine production was as monazite-xenotime mineral concentrates, a byproduct of heavy-mineral sands (HMS) mining and processing. HMS operations typically produce titanium, zirconium, and a variety of other mineral concentrates. In 2022, Australia's REE production was based primarily on production of concentrates from the Mount Weld mining operations. Mount Weld is a carbonatite deposit with ore reserves of 18.6 million metric tons (MMt) containing 8.2% (1.53 MMt) REO equivalent. Total resources at Mount Weld were 54.7 MMt containing 5.3% (2.88 MMt) REO equivalent (Lynas Rare Earths Ltd., 2023). Mining at Mount Weld has been on a campaign basis in support of downstream crack, leach, and separation operations in Kuantan, Malaysia. The Mount Weld operations were initially designed to produce up to 66 thousand metric tons per year (KMt/year) of mineral concentrate containing about 26.5 KMt/year of REO equivalent (Lynas Rare Earths Ltd., n.d.). Lynas has plans to expand mine capacity and move its initial hydrometallurgical processing operations that produce mixed chemical concentrates from Malaysia to Australia.

In Western Australia, Northern Minerals Ltd. commissioned its pilot production at the Browns Range project in 2018. Hard rock ore containing xenotime was used to produce a mixed REE carbonate. In the Australian financial year 2022 (1st July 2021 to 30th June 2022), the pilot plant processed 8.5 KMt of ore and produced 70 Mt of carbonate. Indicated resources for the Browns Range project were estimated to be 4.54 MMt containing about 0.7% (31.7 KMt) REO equivalent. Probable reserves were 3.29 MMt containing about 0.7% (22.3 KMt) REO equivalent (Northern Minerals Ltd., 2022).

In 2020, heavy-mineral sands producer, Iluka Resources Ltd., began processing a stockpile of mine tailings to produce monazite-rich mineral concentrates at its Eneabba operations in Western Australia. The first phase of the project commenced in 2021, and the company produced 44 KMt of concentrate in 2020 and 58 KMt in 2021. In 2022, a second phase was completed to produce a 90% monazite concentrate from stockpiled tailings supplemented with ongoing process tailings. In the third phase of the project, the company planned to use monazite concentrates from potentially multiple sources to produce mixed and separated REE compounds. Reserves of the stockpile were estimated to be close to 1 MMt grading 84% heavy minerals. Monazite and xenotime comprised about 19% of the heavy minerals fraction (Iluka Resources Ltd., 2023a, p. 39; 2023b, p. 14).

Australia has been an active region for mineral exploration and development. Publicly listed companies developing projects with Joint Ore Reserve Committee (JORC)-compliant rare earth reserves in Australia included Alkane Resources Ltd. (Dubbo Zirconia), Arafura Resources Ltd. (Nolans Bore), Australian Mines Ltd. (Sconi), Clean TeQ Holdings Ltd. (Sunrise), Hastings Technology Metals Ltd. (Yangibana), Lynas (Mount Weld), Northern Minerals Ltd. (Browns Range), Platina Resources Ltd. (Owendale), and Scandium International Mining Corp. (Nyngan). According to Geoscience Australia, economic demonstrated resources in Australia in 2021 were 4.26 MMt of REO equivalent (Hughes et al., 2023, p. 12).

1.2.2. Brazil

Brazil was an early producer of monazite mineral concentrates from heavy mineral sands deposits. In addition to mining, some chemical processing of monazite took place from 1949 to 1992 until environmental concerns closed the operations. In 2021, Brazil exported about 833 Mt of mineral concentrates that were produced from existing stockpiles of mixed heavy-mineral concentrates. According to the Agência Nacional de Mineração, Brazil's prior exports were derived from Indústrias Nucleares do Brasil inventories in Sao Francisco do Itabapoana (Andrade, 2019, p. 168).

In 2018, Companhia Brasileira de Metalurgia e Mineração (CBMM) conducted trial processing of monazite-bearing tailings from its Araxá mine and processing operations in the State of Minas Gerais. CBMM Araxá operations produced niobium metal, ferroniobium, and compounds from pyrochlore ore containing about 2.3% niobium oxide. The plant capacity was 1 KMt/year of REO in the form of mixed compounds and pilot capacity for separated compounds...