Linking mineralogical variability to processing: Strategies for a rare earth carbonatite deposit

This paper intends to apply the Hubbert curve to the production of rare earth elements by the United States, China, and total global production. The goal of this research is to see if the production of rare earth elements follows the predicted production forecasted by the Hubbert curve and to observe if the curve can create usable predictions of future production. Global demand for rare earth elements has drastically increased in the modern era due to their unique properties. Global production has increased as well to meet this increased demand. Rare earth elements are a collection of seventeen chemical elements that are used in the production of advanced technologies. The demand for rare earth elements has increased in the modern era with new applications for them being discovered and the increasing demand for green energy which requires rare earth elements in its production. The United States was chosen to be examined due to its long history of producing rare earth elements. The United States was also the largest supplier of rare earth elements before China overtook them in rare earth element production. Ever since China became the top producer of rare earth elements, the United States’ production of rare earth has declined. Production reached zero in 2016 due to the lone company that mines rare earth elements in the country filing for bankruptcy. This caused their only mine to be put on care and maintenance. This meant that the United States had to import all of the rare earth metals it requires until the mine reopens or until new mines are created. China was chosen as the other country to analyze because it has the largest known reserves of rare earth metals and is the largest supplier of rare earth elements in the world market today. China’s supply of rare earth metals for the market is also affected by its own increasing demand for rare earth due to its rising industrial sector and their government trying to preserve their reserves of rare earth metals. It was concluded that observed REE production does follow the trend predicted by the Hubbert curve, but the Hubbert curve does not create accurate predictions of future REE productions due to its simplicity. The first section of this paper is a literature review that scrutinizes previous research done about rare earth elements and the Hubbert curve. The reasoning behind this analysis is to get a better understanding of the state of the rare earth elements market and to create a basis for the research of this paper to be conducted on. Correspondingly in this section, the equation of the Hubbert curve and the theoretical implications of its results will also be discussed. The data and regressions will be described that look at the application of the Hubbert curve to the United States’ rare earth element production, China’s rare earth element production and global rare earth production in the next section. The results of this research will be thoroughly described in the conclusion alongside what implications these results have as well. A bibliography citing all material used within this project will be the last part of this paper.

The Riviera W–Mo deposit is hosted by I- and A-type granitoids of the Neoproterozoic to Palaeozoic Cape Granite Suite that intruded the meta-volcano-sedimentary Malmesbury Group of the Saldania Belt. Scheelite-powellite and molybdenite are the principal ore minerals and are associated with greisen-, reduced endoskarn- and vein-type pervasive alteration of the granitoids. Exoskarn ore makes an insignificant contribution to the total resources. The mineralised body is dome-shaped and located in the roof or cupola of the granitoid pluton. The deposit has an outlined resource of 46 million tons at a grade of 0.216% tungsten (WO3) and 0.02% molybdenum (Mo) with a high grade zone of 7 million tons of 0.30% WO3 and 0.02% Mo. Significant concentrations of Ce–La-enriched allanite, a light rare earth-enriched mineral of the epidote group, were recently discovered in the high tungsten grade, endoskarn part of the Riviera pluton. A resource of some 20 million tons at a tentative average grade of 0.35% ΣREE and has been indicated for this zone. Considering the high demand for rare earth elements this could constitute an economically important by-product and contribute towards the viability of a presently marginal W–Mo deposit. The textural and late stage alteration features of allanite are however complex and could inhibit its recovery and the production of a high grade allanite concentrate. Poikilitic intergrowths of apatite, zircon, monazite, kalkowskite and beckelite, variable chemistry indicated by zoning, metamictization as well as alteration of allanite to parasite and bastnasite will result in poor recovery and present a formidable geometallurgical challenge. Although allanite is not the rare earth mineral of choice by the international metals market the anticipated increased demand for light rare earth elements could change this situation in the future.

Market impacts of environmental regulations on the production of rare earths: A computable general equilibrium analysis for China

This paper analyzes relations between China's export restrictions and rare earth prices in recent years.China has decreased the rates of Value Added Tax (VAT) rebates on rare earths raw materals (ores, metals and compounds) since 2004. It has also increased the rates of export duties on the same items since 2006. It appears that China has taken such measures to restrict outflows of rare earth raw materials, and these measures have been taken several times in recent years. Rare earth prices generally soared for the last several years. For example, price of dysprosium, one of the rare earth elements, has increased by about six times between June 2003 and June 2008.We analyzed relations between China's measures for export restrictions and prices of ten rare earth metals between June 2003 and June 2008 by using regression models. The findings of this analysis are as follows.(1) There is a strong tendency in which rare earth metal prices increase significantly soon after enforcement of an export restriction by China.(2) As China repeats measures for export restrictions, length of time between enforcement of such a measure and occurance of price increase has become shorter.This paper also mentions the possibility that demand for rare earths will be less price elastic in the near future. It is highly probable that growing needs to tackle global warming will require people to buy a greater number of eco-frindly products including hybrid vehicles. In such a situation, demand for rare earths, which are raw materials for essential parts of such products, would increase substantially. In addition, manufacturers of such products would have no choice other than procuring certain amount of rare earths regardless of their prices, since there is few alternative raw materials for these products. Under such circumstances, demand for rare earths would be less price elastic, and thus, rare earth prices in the future are likely to be more volatile.

The global demand for rare earth elements (REEs) is expected to increase significantly because of their importance in renewable energy and clean storage technologies, which are critical for drastic carbon dioxide emission reduction to achieve a carbon-neutral society. REE ore deposits around the world are scarce and those that have been identified but remain unexploited need to be developed to supply future demands. In this study, the Khalzan Buregtei deposit located in western Mongolia was studied with the aim of upgrading low-grade REE ore via magnetic separation techniques. The total REE content in this ore was ~6720 ppm (~3540 ppm light REE (LREE) + ~3180 ppm heavy REE (HREE)) with bastnaesite, pyrochlore, synchysite, and columbite-(Fe) identified as the main REE-bearing minerals. As the particle size fraction decreased from −4.0 + 2.0 mm to −0.5 + 0.1 mm, the recovery by dry high-intensity magnetic separation (DHIMS) increased from 20% to 70% of total rare earth oxide (TREO) while the enrichment ratio reached 2.8 from 1.3. Although effective, gangue minerals such as quartz and aluminosilicates were recovered (~22%) due most likely to insufficient liberation. Meanwhile, the wet high-intensity magnetic separation (WHIMS) could produce a magnetic concentrate with TREO recovery of ~80% and enrichment ratio of 5.5 under the following conditions: particle size fraction, −106 + 75 μm; feed flow rate, 3.2 L/min; magnetic induction, 0.8 T. These results indicate that combining DHIMS and WHIMS to upgrade the low-grade REE ore from the Khalzan Buregtei deposit is an effective approach.

The presently increasing demand for rare earth elements (REE), particularly in high-tech and “green energy” applications, has led to global interest in the distribution, origins and formation conditions of REE deposits. The World’s first hard-rock REE sources, the polymetallic deposits of Bastnäsfältet in Bergslagen, central Sweden, were also the place of the original discovery of several REE and many of their host minerals. Similar deposits with high concentrations of REE occur along a > 100 km corridor in the region and they share a number of geological and mineralogical features; all comprising Palaeoproterozoic, skarn-hosted magnetite-REE mineralisation of ambiguous origin. Here we report oxygen isotope data for magnetite and quartz, and oxygen and carbon isotope data for carbonates from ten of these classic deposits, to model and assess their mode of origin. Combined with existing geological observations, the isotope results support an origin in a c. 1.9 Ga shallow-marine back-arc, sub-seafloor setting, where felsic magmatic-sourced, high-temperature fluids reacted with pre-existing limestone interlayers, leading to localised skarn formation and magnetite-REE-mineral precipitation. These findings help us to better understand the geological processes that have produced economic REE mineralisation and may assist future exploration for these critical commodities.

The increasing global demand for rare earth elements (REEs), particularly lanthanum, cerium, and neodymium, has led to a growing interest in alternative and sustainable sources. Monazite, a phosphate mineral rich in light REEs, is a promising resource in countries like Bangladesh, where monazite-containing heavy mineral sands have been identified along the southeastern coastline and in the extensive river systems. Monazite placer-style deposits in the Cox’s Bazar–Teknaf–Moheshkhali coastal belt and inland rivers are formed through prolonged weathering and sedimentation processes and contain significant concentrations of La, Ce, and Nd. Exploration of monazite in Bangladesh is still at a preliminary stage, but laboratory and pilot-scale beneficiation and mineral separation studies show a favorable recovery rate. Further work is needed to quantify reserves, monazite properties (chemistry, grainsize), and amenability to beneficiation. This review study critically evaluates the geological setting, mineralogical characteristics, and extraction potential of Bangladeshi monazite within the broader context of global REE recovery. The applicability of modern, environmentally sustainable extraction, and beneficiation technologies to local monazite resources are assessed and used to identify pathways for developing a sustainable REE industry in Bangladesh. Our analysis indicates that integration of advanced extraction technologies and local mineral beneficiation could support the development of a strategic REE supply chain in Bangladesh, contributing significantly to regional and global resource security.

Retrospective on Recent DOE-Funded Studies Concerning the Extraction of Rare Earth Elements & Lithium from Geothermal Brines (Final Report)

The west coast of South Africa is well known for its Cenozoic unconsolidated marine and aeolian placer deposits. The gem-quality diamond deposits have been effectively depleted; however, the significant heavy mineral concentrations are actively exploited at Namakwa Sands. This world-class mineral sand has an inferred resource of some 900 million tons at a grade of ~10% total heavy minerals (THMs) from which high-grade concentrates of zircon, rutile and leucoxene are extracted and titanium slag and pig iron are produced. Gangue minerals consist of garnet, pyroxene, kyanite, amphibole, apatite and monazite. Several other resources including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present-day beach placers demonstrate the vast heavy mineral potential along the west coast. The increased global demand for the rare-earth elements (REEs) uranium and thorium has initiated interest in the economic potential of gangue minerals from these placer deposits. The present quantitative mineral distribution and mineral chemistry study has shown that monazite, impure zircon, leucoxene and garnet are common constituents that host significant concentrations of the REEs uranium and thorium. The total estimated resources in the Namakwa Sands deposit amount to 250 kt REEs, 4.7 kt uranium and 10.5 kt thorium. Monazite is the most significant contributor to the total thorium and light REE resource, whereas zircon is a heavy REE and U-enriched. Garnet and leucoxene show low concentrations of these elements and make a minor contribution to the total resources. Results from the Namakwa Sands deposit suggest that the west coast of South Africa as a whole presents a vast untapped resource for these elements. Considering the anticipated increasing demand for rare earths and possibly thorium, these resources could be produced as a low-cost by-product from existing and future ilmenite–zircon–rutile producers, thereby increasing the in situ value of the placers and ultimate revenue.

The unique properties of rare earth elements (REE) have resulted in their being crucial to a growing number of emerging technologies. As the demand for REE currently exceeds annual production, the present worldwide crisis for REE will probably continue for the foreseeable future. Hence, it is highly likely that the availability of REE used in the metallurgy of cast iron will be significantly reduced and alternatives to REE usage may have to be developed. Graphite nodules nucleate heterogeneously on particles formed in the melt, having a duplex structure (sulphide as a core and oxide/silicate as a shell). Mg, Ca and REE appear to act in the nucleation first stage, while Si, Al, Mg, REE, Ca, Sr and Ba act predominately in the second stage. Generally, REE are employed in ductile irons to accomplish the following tasks: (a) neutralize tramp elements such as Ti, Pb, Bi, As etc; (b) assist in nodulizing or provide a supplementary effect to Mg to promote spheroidal graphite shapes; (c) assist in nucleating graphite. When anti-nodularising Thielman control factors (K) are less than 0.8, REE are usually not required since there are no trace elements to neutralize. REE are useful for K factors between 0.80 to 1.20 and are mandatory for K factors greater than 1.20. Theilman factors greater than 2.0 will always require REE. When Theilman factors are less than 0.80, REEreslevels of 0.01% are usually more than sufficient for ductile iron production. Three ductile iron inoculation alloys were selected for this research: (a) a conventional Ca bearing 75% FeSi inoculant (Ca-FeSi), used at a high consumption level; (b) an improved conventional Ca-FeSi alloy that incorporated active inoculating elements, such as Ba or REE, used at a medium consumption level, and (c) a combination of a commercial inoculant, such as Ca-FeSi alloy, used with a separate oxy-sulphide inoculant enhancer alloy addition. The last inoculation variant provided the best structural parameters and the lowest consumption level.

Addressing criticality for rare earth elements in petroleum refining: The key supply factors approach

Rare earth elements (REEs) are increasingly critical to the high-technology and low-carbon economy. With a shift to sustainable socioeconomic development that aims to be less fossil fuel dependent, global demand for REEs continues to rise, despite their uncertain supply chain and high environmental impact of production. Here, we review recent research on REEs, including global reserve assessment, REE-based applications, major REE production pathways, environmental impacts, and the potential to leverage circular economies within the REE industry. The main objective of this review is to provide an overall socioeconomic and environmental perspective of the REE industry with a central focus on environmental impacts of various REE-related activities. The literature reveals significant interest in extracting REEs from secondary materials(e.g., tailings, bauxite residues, coal combustion ash) and electronic wastes. However, some of these REE recovery processes are not yet economically profitable and environmental-friendly. Continued technological advancements and increasing demands for REEs may entice countries with recently discovered REE reserves to break the current monopolistic REE supply chain. Furthermore, the sustainability of REE usage may also depend on consumer awareness of environmental and human health impacts associated with end-of-life electronics that contain REEs. On the other hand, REEs may show promise in sustainable agriculture and environmental applications. Nevertheless, further research on REE ecotoxicological impacts is required to establish environmental regulations that protect the environment and human health.

Demand for rare earth elements (REEs) is increasing, and REE production from ores is energy-intensive. Recovering REEs from waste streams can provide a more sustainable approach to help meet REE demand but requires materials with high selectivity and capacity for REEs due to the low concentration of REEs and high competing ion concentrations. Here, we developed a phosphate polymer nanogel (PPN) to selectively recover REEs from low REE content waste streams, including leached fly ash. A high phosphorus content (16.2 wt % P as phosphate groups) in the PPN provides an abundance of coordination sites for REE binding. In model solutions, the distribution coefficient (Kd) for all REEs ranged from 1.3 × 105 to 3.1 × 105 mL g-1 at pH = 7, and the sorption capacity (qm) for Nd, Gd, and Ho were ∼300 mg g-1. The PPN was selective toward REEs, outcompeting cations (Ca, Mg, Fe, Al) at up to 1000-fold excess concentration. The PPN had a Kd of ∼105-106 mL g-1 for lanthanides in coal fly ash leachate (pH = 5), orders of magnitude higher than the Kd of major competing ions (∼103-104 mL g-1). REEs were recovered from the PPN using 3.5% HNO3, and the material remained effective over three sorption-elution cycles. The high REE capacity and selectivity and good durability in a real waste stream matrix suggest its potential to recover REEs from a broad range of secondary REE stocks.

As demand for rare earth elements (REEs) increases, biotechnological solutions to their extraction and purification are becoming more critical. Identification of chassis organisms capable of surviving in high REE concentrations is a crucial step towards development of sustainable biotechnologies. In this study, we show that growth of mesophilic Escherichia coli is not significantly inhibited by < 300µM REEs in complex media of, but in phosphate-depleted minimal media a half-maximum inhibitory concentration (IC50) for REEs is 80 ± 100µM. REE-utilizing mesophile Pseudomonas alloputida KT2440 is growth-impaired in presence of REEs, with an IC50 of 100 ± 20µM. In contrast, we demonstrate that extreme acidophiles survive in conditions of 500µM REEs without apparent inhibition of growth. Indeed, we observe that hyperacidophilic bacteria Acidithiobacillus ferrooxidans, A. thiooxidans, and A. caldus appear to enter log phase earlier in presence of REEs and grow to significantly higher densities. Acidophilic archaeon Sulfulobus acidocaldarius, a hyperthermophile, is similarly not significantly inhibited by 500µM REEs. These data indicate that acidophiles have broad-range stress tolerance mechanisms that apply to REE stress. Importance: Rare earth elements (REEs) are essential for a diverse and expanding range of high-technology applications, which are an important part of the industrial economy. Application of biomining technologies could introduce "greener" extraction and processing steps, however, many fundamental challenges must be addressed before a biological approach to REEs recovery and separation can be fully adopted at scale. Fundamentally, any chassis organism used for REE biomining must be able to tolerate high concentrations of REEs, and existing literature along with this study demonstrate that neutrophilic mesophiles are highly sensitive to REEs. In contrast, we demonstrate that mesophilic extreme acidophiles and thermophilic acidophiles exhibit inherent REE tolerance. This phenomenon highlights their potential for bioprocessing and corroborates existing evidence that the extremophile response to REE presence may allow for broader adaptation behavior in comparison to other model chassis strains.

The ability to secure rare earth elements (REEs) in the United States is of concern due to the rapid growth in demand and the monopolistic supply chain. The demand for REEs has skyrocketed in recent years due to the development of many green technologies. The United States and many other countries are currently reliant on China for REEs, who currently control greater than 90% of the global supply. Due to the severe impact of previous Chinese export quotas, it is important to lessen the reliance on importation and explore methods of recycling REEs from secondary sources. A secondary REE source of interest is acid mine drainage (AMD), which has been shown to contain REE concentrations far above that of natural water sources. Focusing on AMD sources in northeastern West Virginia, the objectives of this study include 1) determining the viability of recovering REEs from AMD via selective precipitation, 2) assessing correlations between the raw water characteristics and the quality of the REE sludges produced, and 3) determining the effects of redox condition and flocculant usage on the precipitation procedure. To satisfy the first objective, acid mine drainage was collected and pH adjusted sequentially between pHs 3.0 and 8.0. The pH ranges of gangue metal and REE precipitation were analyzed to determine if efficient separation of REEs could occur. Based on the analysis, recovery of REEs was efficient due to the well defined separation of removal pH ranges. To achieve the second objective, AMD samples were collected from seven sites across northeastern WV. Each sample was adjusted sequentially to pH 4.0, 5.0, and 8.0. The composition of the precipitates and overall REE recovery were analyzed and compared for each sample. Linear regression was then used to assess correlations between raw water characteristics and the grade of the precipitates. It was determined that the precipitate grade was independent of the raw water REE concentration and could not be accurately predicted using raw water characteristics. The third objective was achieved by the repeating the precipitation procedure under varying redox conditions, which included complete oxidation, partial reduction with nitrogen sparging, and partial reduction without nitrogen sparging. The effects were assessed by comparing changes in precipitation patterns of gangue metals and REEs. The completely oxidized condition led to a greater separation of pH range between the metals and REEs when compared to the partially reduced conditions. The effects of flocculant usage were also examined for