Current and Future Trends of Rare Earth Elements

3. Characteristics and Versatility of REE 4. Concluding Remarks

1. Introductory Remarks

Rare earth elements (REE) have become an important group of metals used in various high tech industries. In this brief note, the author has attempted to discuss the importance of these valued metals, their applications and current and future uses and trends of these elements.

The author has attempted to describe what REE are and how they are used in high tech industries.

He has also made his view and suggestions to the best way to approach to this important technology from the Korean perspective.

2. What are Rare Earth Elements?

REE are regarded as “Gold” in the modern era since they play a critical role to the information age. They will serve as an important piece of a clean and efficient green energy future. The use

of REE is vast including iPods, Blackberry’s, plasma TVs and many more. They are also heavily used in military applications. They are necessary components of the magnets in electric motors and soon to be important in electrical cars.

The development of the nation’s wellbeing and wealth is hinged upon the appropriate industrial use of REE. Their use in various industrial sectors is critical in the race of modernization of the nation. It is imperative therefore, to understand where they occur, how to get them and also how to apply its use in an appropriate manner.

REE consist of seventeen elements in the

periodic table (see Figs. 1&2). More specifically,

it consists of fifteen lanthanide group elements

and scandium, Sc and yttrium, Y. These elements

occur in nature in the same ore deposits and they

are generally not rare in occurrence as the name

indicates. In fact, they are relatively abundant in

the Earth’s crust. For example, cerium is the 25

(Fig. 1) Periodic table showing rare earth elements

(Fig. 2) Rare earth oxides. Clockwise from the front center: Praseodymium, cerium, lanthanum,

neodymium, samarium, and Gadolinium

(Fig. 3) Global production of REE for the period of 1950‐2000

most abundant element at nearly 70 ppm which is similar to those of copper and zinc

.

In general there are two types of ore deposits containing REE, one being the “Mountain Pass Type” consisting primarily bastnasite, which contains largely Ce, cerium and La, lanthanum and the other, lateritic ore type, which contains mostly Y, yttrium, La, lanthanum and Nd, neodymium. The former is found in Mountain Pass, CA of the US and the latter is found in China.

The production of REE was used to be dominated by the US for the 70’s and 80’s but

lately the majority of REE has been produced by China. (Fig. 3) As noted in Fig. 3, the US used to produce the majority of REE. However, since mid 1980s, the production rate has been declined gradually and eventually in recent years, the US has been heavily relied upon the importation of REE from China. One of the reasons of discontinuation of production of REE in the US was due to environmental concerns during the mining and processing of these elements.

In recent years, the US and other developed countries have heavily relied upon China for their exportation of REE. However, China has recently declared not to export these valuable elements any more. As a result, many countries are seeking alternative ways of getting these elements.

Due to the advancement of new technologies,

the excavating and processing of REE can be

carried out in an environmentally friendly manner

and furthermore, since the value of these REE is

so significant in the development of nations’ high

tech industries, there is an urgent need to explore

processing and manufacturing REE based

products.

(Fig. 4) Flow‐chart showing a future strategy for the advancement of REE technology to the fast development of automobile and

electronic industries. In general, the most use of these elements is found in catalysts representing about 47% of the total consumption. They are also used in metallurgical applications and alloys, 13%, special alloys, 11%, glass polishing and ceramics, 10%, permanent magnets, 9%, special ceramics, 5%, computer monitors, lighting, radar, televisions, and x‐ray intensifying films, 5% in this order.

It is notable that the use of REE grows slowly but steadily in the special alloy industry. The use of Eu, europium is notable especially because of its extensive use in color cathode‐ray tubes and liquid‐crystal displays (LCD), which is used in computer monitors and TV. What is more notable is that there has not been found any substitute for this element.

The use of Er, erbium is also notable in that its unique use in fiber‐optic cables is unparallel. The advent of this application enabled to replace the copper wires and cables since fiber‐optic telecommunication cables provide much greater bandwidth. The use of Ce, cerium in polishing agent for glass, mirrors, and eye‐glasses is also notable. Many of REE is used in high tech industries such as in various alloys used in electrical and electronic components applicable in

control catalysts is well known. REE used in magnets reduces the weight of many pieces of equipment such as automobiles. Some REE are used in the reduction of carbon oxide emissions ᡊ There is undoubtedly more work in need to improve and develop more energy efficient and environmentally friendly applications of REE based alloys and compounds in the future. Table 1 represents a summary of the notable use of these elements.

Fig. 4 illustrates an overview as to how best to

approach in taking full advantage of utilization of

these very valued elements in view of the current

situation facing the Korean scene with respect to

At. No Symbol Name Applications 21 Sc Scandium Aerospace components, mercury‐vapor lamps

39 Y Yttrium Garnet laser, TV red phosphor, high temperature superconductors, microwave filters

57 La Lanthanum High refractive index glass, flint, hydrogen storage, battery electrodes, camera lenses, catalysts

58 Ce Cerium Oxidizing agent, polishing powder, yellow colors in glass and ceramics, catalysts, flints for lighters

59 Pr Praseodymium Rare‐earth magnets, lasers, colorant in glasses and enamels, glass used in welding goggles, ferrocerium firesteel products

60 Nd Neodymium Rare‐earth magnets, lasers, violet colors in glass and ceramics, ceramic capacitors

61 Pm Promethium Nuclear batteries

62 Sm Samarium Rare‐earth magnets, lasers, neutron capture, masers

63 Eu Europium Red and blue phosphors, lasers, mercury‐vapor lamps, NMR relaxation agent

64 Gd Gadolinium Rare‐earth magnets, high refractive index glass, lasers, X‐ray tubes, computer memories, neutron capture, MRI contrast agent, NMR relaxation agent 65 Tb Terbium Green phosphors, lasers, fluorescent lamps

66 Dy Dysprosium Rare‐earth magnets, lasers

67 Ho Holmium Lasers

68 Er Erbium Lasers, vanadium steel

69 Tm Thulium Portable X‐ray machines

70 Yb Ytterbium Infrared lasers, chemical reducing agent 71 Lu Lutetium PET scan detectors, high refractive index glass

<Table 1> lists various applications of REE elements

REE. As one of the fast growing industrialized countries in the world, the need of using REE in Korea is growing very fast. The author feels that it is very critical to identify the domestic deposits for REE. As mentioned earlier, REE is not really rare in their occurrence on earth. They appear in a scattered manner almost everywhere but the problem is that their content in a deposit has to be high enough to be economical. As a result, a significant effort should be exerted to locate these deposits. Japan has recently identified a vast deposit in the ocean bottom near her territory and Korea should look into various possibilities of the deposits of REE.

Once the economical deposit is identified, an

environmentally responsible mining and processing approach has to be taken. There are standard references to be used how to approach to this objective.

The next step would be extraction of REE from the concentrated portion of the above operations. There are in general two approaches to this. One is to extract REE by hydrometallurgically and the other approach would be by a high temperature approach. The common approach to extracting REE from their ores is the water based leaching. The principles involved in this approach are detailed in many references.

Selective leaching of the individual element is

practically impossible and as a result, all of REE

existing in an ore deposit are extracted into the

It is generally understood that all of the above steps shown in Fig. 4 are relatively straight forward as far as the technologies and fundamentals are involved. The key to the success of implementing the REE technology is mastering the technology of making high purity of the individual element from mixtures of many REE. The second important step is how best to advance in making new and better alloys and compounds to be used in various areas.

4. Concluding Remarks

Rare earth elements are not really rare in their occurrence and they occur almost everywhere. It is vital for Korea to identify the ready source and also to develop the technology of its extraction and advanced applications for the better use of REE. It is the author’s view that Korea should identify its source in its land. There is no reason why Korea cannot identify these very important elements used in various industries.

The Koran Government should seek a consorted effort to approach the urgent need of securing this important resource. It should work hand in hand with governmental research centers, educational system, also relevant industries. It

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Author’s Brief Biography

∙ Dr. Kenneth N. Han obtained his B.S. and M.S. degrees from Seoul National University (SNU), an M.S. from the University of Illinois and a Ph.D. from the University of California, Berkeley.

∙ He is currently a Visiting Professor at Seoul National Univeristy, and was the Founding Director and Chair Professor of the KEN (Korea Environmental and Nano Research Center) which was established in June of 2006. He was with the Department of Chemical Engineering, Monash University, Melbourne, Australia from 1971‐1980. In 1981, he joined the South Dakota School of Mines and Technology (SDSM&T). He was head of the Department of Metallurgical Engineering from 1987‐94, dean of the College of Materials Science, Engineering from 1994‐99 and Dean of Graduate Studies from 2004‐2006. He was a Regents Distinguished Professor in the Department of Materials & Metallurgical Engineering at SDSM&T before he retired in December of 2006.

∙ He was inducted into the National Academy of

Engineering of the US in 1996. He is a foreign member

of the National Academy of Engineering of Korea since

1998 and was inducted to the Korea Academy of

Science and Technology in 1999.