1. Introduction
As the global population approaches 8 billion people and the climate becomes increasingly unpredictable, the careful management of the Earth’s finite resources becomes more important than ever. The widespread use of nonrenewable carbon as an energy resource has lead to the buildup of greenhouse gases in the atmosphere. Continued consumption will also eventually lead to global energy shortages. Most policy makers understand that to avoid potential climate and energy crises, energy production must become more diverse and sustainable. Adopting of carbon-free or “green” energy technologies such as electric cars, wind turbines, and solar panels has become one of the best ways to meet energy demands without causing greater climate crisis. Despite this rise in demand, the production of renewable technology is limited by the availability of rare earth elements (REEs), elements that are essential to the fabrication of key technical components. In fact, global shortages of one such rare earth element, neodymium (Nd), have greatly hindered the production and use of green technology infrastructure. Examining the factors affecting the global supply of neodymium, therefore, can provide valuable insight into the future of clean energy infrastructure.
2. History and Industrial Uses
The rare earth elements are a group of seventeen metallic chemical elements found on the periodic table: the lanthanides (in the bar at the bottom of the table) plus scandium and yttrium. All share similar chemical properties, which are tied to the configuration of electrons in the atomic structure. Due to this chemical similarity, they often form together in rocks and minerals.
Minerals containing REEs were discovered in Sweden in the late 1700s. However, it was not until 1885 that Carl Auer von Welsbach, an Austrian inventor and chemist, discovered neodymium. Through experimenting he uncovered didymium, a recognized element, was really a mixture of two elements, neodymium and praseodymium. It is a lanthanide and is rarely found naturally in its isolated, metallic form. The first known sample of pure metal, which is silvery-white in color and tarnishes rapidly in air, was produced in 1925. By 1927 neodymium was being used commercially as a reddish-purple glass dye. It continued to be a popular chemical additive in glass production and glazes before being used in metallic alloys.
The discovery of neodymium-iron-boron (NIB) permanent magnets in 1982 changed the technological world. Light, strong, and relatively inexpensive, these magnets exhibit powerful forces even at small sizes and are perfect for use in sleek, high technology applications. It is a soft, malleable metal and is able to be hammered quite thin without losing crucial physical properties. Today, few products do not take advantage of these efficient magnets and every industry has been influenced. The small, yet amplified speakers in smart phones are made from NIB magnets, as are the vibrating mechanisms and other components of handheld electronics. They are used in graphics and screens, fiber optics, LED lights, and lasers. Most hard drives and data storage devices have neodymium components. MRI imaging machines and other medical imaging devices have changed the way we do medicine. However, it is in the energy sector that we see the most recent explosion of use and concern over whether consumption of REEs is sustainable. Rare earth metals, and neodymium in particular, are vital components of the motors and batteries of electric cars. Large wind turbines and generators can use 2 tons of magnets. The solar cells and mounts for solar panels are even made with neodymium.
The expanded use of neodymium in these key energy markets has grown into a multitrillion-dollar market and critical demand will continue to grow exponentially as global consumption of green energy infrastructure increases. For the past several years, world governments have been concerned with these trends and are anticipating future supply restrictions. Already economic concerns have lead to irregular market prices, trade restrictions, and a concerted effort to decrease reliance on these key elements for national security concerns. A 2015 Ford Motors report on future manufacturing trends, “Rare Earths in Vehicles: Current Problems and Future Directions”, stated “a shortage in supply for neodymium, praseodymium and dysprosium is possible by the end of this decade.” While increased demand has certainly led to temporary shortages in supply, there are other factors to consider when weighing the long-term sustainability of the global supply.
3. Nature of REE Mineral Deposits
While historically thought to have been rare, it is now understood that deposits of rare earth elements are widely distributed in the earth’s crust. In fact, neodymium is more abundant (at 20 ppm) than, lead, silver, or gold. Deposits can be categorized as magmatic and sedimentary. Magmatic REE deposits are in primary carbonatite, peralkaline, or pegmatitic rocks and contain the highest grade of ore. Carbonatites like those found at the shuttered Molycorp mine in Mountain Pass, CA form almost exclusively in continental rift zones and are only known to exist in 330 locations, making them rare. REEs constitute around 3,500 ppm of the rock and are ideal targets for mining neodymium. Sedimentary or placer deposits of eroded heavy mineral sands and pebbles are found in tributary streams beds or lake and ocean shores. Placers often contain REEs at higher concentrations than hard rock deposits but the deposits are smaller, more variable, and contain high quantities of radioactive minerals. Many coal deposits also carry REEs, though as with placers, concentration varies from site to site.
The main minerals that contain high-grade concentrations of neodymium and other REEs are the oxides bastnäsite and monazite. Rare earth minerals often contain multiple elements of economic value, which enables one mining operation to extract diverse offerings. At Mountain Pass, cerium, lanthanum, neodymium, and europium were extracted. The notoriously difficult processes of isolating and separating the tightly bonded elements from the mineral matrix unfortunately offset the convenience of having so many elements in the same ore. Removing just neodymium involves multiple rounds of ion exchange and solvent extraction. The entire processing cycle from start to finish is a process of mining, crushing, concentration, chemical treatment, reduction, refining, and purifying.
4. Mining and Refining
Most neodymium deposits are shallow enough to be excavated in open pit mines, in a design similar to stone quarries. Stepped walls ring deep, funnel shaped pits exposing walls cut by drill and blast operations. Trucks haul ore and waste rock out of the pit via ramps and into benefaction facilities, where ore minerals are separated from the host rock. All material is crushed into sand and then further wet ground into a magnetic ore pulp. Magnetic separation removed the nonmagnetic portion from the pulp before it is fed into a chemically enriched floatation cell where minerals are further separated by specific density. Electrostatic separators may also be used to separate minerals based on molecular polarity and size by exposing them to an electric field. Additional physical and chemical steps may be added or removed depending on the mineral being mined and the concentration of ore. Regardless of the exact process, considerable amounts of energy and water are consumed in these separation processes before elements are even liberated. There is also extensive pollution; dust clouds and large amounts of chemically contaminated rock slurry are generated.
To free the element from the host mineral a few different methods are employed. The most common large-scale neodymium purification methods begin with multiple stages of solvent extraction, called “cracking” or “stripping”. Solvents are applied to the separated REE concentrate and mixed to encourage ionization, or leeching, of different elements, which are removed. Another chemical “scrubbing” phase may be added, which removes additional elements like radioactive thorium. The final mixture is then repeatedly exposed to an aqueous solution where ions have a higher solubility, encouraging the ions to migrate until REE compounds concentrate into salts of desired purity. When possible, chemical treatments are repeated or reused, however significant waste is produced.
Surplus from the extracting and refining processes may be purified to redeem water, however the excess slurry, called mine tailings, is generally too contaminated by chemical or radioactive waste to be reused. Sometimes this waste is deposited back into the open pit and covered by landfill and clay cover during site rehabilitation at the end of the mine’s lifecycle. However, during active mining this is often not possible and tailings are held in ponds or dams, which are toxic and can harm surrounding groundwater and ecosystems through acid drainage if not properly managed.
The final period of refining converts the REE salts into a very pure rare earth metal. Technical, high-energy processes of molten salt electrolysis and metallothermic reduction strip the remaining elements from the salt mineral, leaving behind pure neodymium. As neodymium oxidizes quickly in air, after purification it must be stored away from oxygen in mineral oil and wrapped in plastic to prevent tarnishing.
5. Supply Risks and Policy
Neodymium is listed as a critical raw material due to the fact that extraction, refining, and manufacturing almost entirely limited to one country – China. According to the USGS, China contains 38% of known REE reserves, followed by 19% CIS/Russia, 13% USA, 5% Australia, and 22% other countries. Despite this distribution, China currently produces and refines more that 87% of global rare earth metals, followed by CIS and Malaysia. This was not always the case. From 1966 to 1984, 50% of the global supply of neodymium came from Bastnäsite from Mountain Pass, CA. In 1985, China began earnestly exploited their reserves and diversified supply chain offerings until in 1990, it surpassed US production. Cheap labor, lax regulations, inexpensive coal-burning energy plants, high-grade ore deposits, and high demand from a booming manufacturing sector led neodymium prices to plummet. As the more affordable Chinese offerings flooded the global marketplace, mining in other countries became economically unviable. Chinese market dominance eventually led to the closure of Mountain Pass mine in 2002, severely limited REE production and exploration in other countries.
This began to change in 2011 when China introduced export quotas on REEs out of concern for their domestic supply. Booming renewable energy and technology manufacturing caused domestic demand to skyrocket, and the grade of ore being mined began to shrink, causing less refined metal to be produced. The affect of the Chinese monopoly of the supply neodymium was truly realized. Only one mine, the Bayan Obo deposit in Mongolia produced more than 46% of China’s REEs. Many countries began to fear for their own domestic markets and how this lack of supply diversity would affect economies and national security. Once self reliant, the US had become 100% dependent on neodymium imports from China. And in 2011 the Chinese embargo caused global prices to rise three to fivefold in just a few months.
The EU, USA, and Japan filed a formal complaint to the World Trade Organization, which was upheld in 2014, and begun discussing the need for better management of the global supply. Even before the supply crises brought on by the Chinese export quotas, the US government had grown concerned with the independence and diversity of American energy offerings. The Department of Energy launched the Advanced Research Projects Agency-Energy program in 2009 to fund the development of improved energy technology in order to better protect future economic and energy security. After the neodymium market volatility began they added the Rare Earth Alternatives in Critical Technologies (REACT) program, established to develop alternative materials to REEs. In 2011, ARPA-E awarded 31.6 million dollars to fund Rare-Earth Substitute projects.
Countries around the world, especially since uniting for the Global Climate Agreement (GCA), are beginning to understand the need for policies that apply the principles of sustainability to the management and development of future neodymium markets. Green infrastructure is a key priority of the GCA and therefore a stable REE market is vital, which has been reflected by a renewed investment in diversifying and expanding the supply.
As previously mentioned, one such method of doing this is to decrease reliance on neodymium as a material. Engineers across the globe are now redesigning technical components to require less neodymium to produce. While production of renewable infrastructure may be increasing, this will conserve the supply stretching it further until alternatives can be found. However, it is possible this will only shift the problem to another raw material. Dysprosium, for instance, can substitute for part of neodymium in magnets making them more efficient, but its supply is even more critical.
Another underutilized method is technological recycling. Most REE-bearing tech in the United States is simply thrown into a landfill. Smartphones, cars, washers and dryers, all are often discarded after the product life cycle is complete and not repurposed or recycled. Part of this is due to product manufacturing. Patents and concerns about reproduction have lead manufacturers to make components less replaceable or removable, and ability to recycle is not a priority built into the design of products. Part of this is also due to a lack of recycling infrastructure. Most people do not have access to recycling services or knowledge on how to properly dispose of technical waste.
The final, and most effective method is to invest in the exploration of new deposits or the development of underutilized deposits.
6. Economic and Other Considerations
A mineral deposit is only designated as a natural resource ‘reserve’ if it can be exploited economically using existing technology, a rare designation. Most deposits are too small or not concentrated enough to be worth extracting once the market price is weighed against the cost of production. However, due to skyrocketing global demand many countries are reconsidering traditional economic criteria of value and cost when evaluating viability against necessity. One way a country or company might consider these competing factors influencing production is by performing a Life Cycle Assessment.
These assessments are methods for evaluating the environmental and social cost of a product through the supply chain. They are able to consider and normalize all relevant costs of energy, resources, emissions, and waste against the benefits. This allows variable measurements like human and environmental costs to be equalized for evaluation and comparison. Some fixed variables effecting labeling a deposit a reserve include: geographic distribution, concentration, and mineral type. Some more variable factors are: regulatory regimes; commodity price; technology for extraction and production.
These variable factors can be observed in a case study of the Mountain Pass Mine in California. Once the largest producer of rare earths in the world, the site had closed not because it ran out of ore, but because of costs. New environmental restrictions coupled with the drop in market price stopped the mine from being profitable. The mine later changed hands and in 2011, after 3 years of development, Molycorp received funding and environmental permissions to begin reopening the mine. Operations restarted in 2012 and full production was achieved when in 2015, the company filed for bankruptcy and held $1.4 billion in debt. Poor financial management, not production failure, stopped operations for a second time.
Part of this may be explained by cost of extraction. Some deposits are also more energy intensive than others to put through the entire recovery cycle. The cost of labor is also much higher in the US than in other countries, where environmental and regulatory rules can also impede the creation of new mines. Mountain Pass was a well researched and established mining site and it still took years to reopen operations. It can take 10+ years to open a new mine that is not as well developed even with government support and investors.
As previously portrayed, not all of the costs of production are economic. Processing REEs comes with many environmental risks. Coal powered plants often drive mining and processing facilities across the world. Many radioactive minerals such as thorium are found in REE deposits, and the chemicals used in separating minerals, such as sulphates, ammonia, and acids are carcinogens. Economic grades of neodymium are low compared to other metals like iron and one ton of REE metal can produce 2,000 tons of waste material and 10 million tons of wastewater a year. Most of this waste material is pumped into holding ponds or tailings dams and has been historically poorly managed. The cost of managing pollution can be prohibitive. Slave or near-slave labor working conditions have occurred in mines from many countries, abuses carried out to keep production costs and market value low.
These unseen costs and trends are rarely considered when measuring the economic cost of buying a new electronic device. Many environmental scientists and policymakers can also forget that long-term development of raw materials infrastructure is required if the US is to replace its current reliance on fossil fuels. It is easy to think that environmental laws protect or absolve US consumers of the liabilities associated manufacturing-related harms. While these laws are important, they have simply encouraged outsourcing of production and pollution to other countries.
7. Current Outlook and Emerging Trends
On the whole the neodymium market is greatly improved since 2011. Prices are stable and steadily rising, there are more diverse offerings, and globally there is a greater awareness and better management practices in place to safeguard the supply. Glass and ceramics currently remain the key drivers of industrial consumption and demand is expecting to rise with the housing markets of growing economies like India and China. Production of Australian deposits has increased dramatically in the last 6 years, from 3,200 tons in 2012 to 20,000 in 2017. While the United States does not currently have any active mines, many sites including some in Wyoming, Idaho, Colorado, New Mexico, and California are under development. Many researchers are also examining new potential venues of extraction. Many coal deposits contain REEs and materials analysts have been experimenting with new extraction techniques to determine the viability of mining such deposits for neodymium and other metals in Kentucky and Appalachia.
The future trends in the consumption of neodymium are greatly dependent on market prices and technological advancements. The global energy market is moving to lessen its reliance on fossil fuels or carbon energy storage, and is actively investing in renewable energy infrastructure. While renewable technology is cleaner and becoming progressively cheaper, there is currently no way to store all of the energy produced resulting in much of it being lost. This is inefficient and leads to gaps in energy services; a fact not lost on renewable energy producers. There is now a huge demand in the market waiting for an energy storage device capable of capturing this lost energy and holding it until the need arises. Long-term energy storage is essential to a full energy transition. Once energy suppliers adopt a suitable system, infrastructure replacement is expected to be swift, and to require massive stockpiles of neodymium.
8. Discussion and Conclusions
Neodymium is an unusual resource in that supply does not predetermine demand or the cost. Its discovery has lead to some of the biggest technological breakthroughs in human history. In short: it has changed the world. Most people rely on it for their daily needs, even carry it in their pocket, and yet will probably never have heard of it despite the fact it is very likely to change the world again. REEs and neodymium, in particular, are classic case studies of what can happen when resources are taken for granted or improperly managed. It is therefore vital that this resource is nurtured and developed. While national security and energy independence are important concerns to protect, American consumers must also become more aware of the true environmental and economic cost of outsourcing valuable resources and manufacturing jobs in exchange for cheaper goods. Fortunately global leaders have united to find solutions for these and other these concerns, and for now, the future of neodymium and humanity looks bright.