World rare earth oxides

World demand for the rare earth elements is established in the range of 25 000 tons per year - calculated as rare earth oxides. 

If we assume current world production of all rare earths to be of the order of 35,000 tons per year, expressed as rare earth oxide, then approximately 17o of this total, equating to about 230 tons, represents the current level of production of pure metals. While in itself this figure may appear insignificant, it is necessary to view it in the light of two other factors. First, expressed in monetary terms the 17o equates to nearer 1% of total value and secondly, over the past 3 years demand for pure metals has been increasing at a rate approaching 20% per year which, if sustained, could radically change the face of the industry within a short space of time.(l )... 

RARE-EARTH ELEMENTS AND METALS. Sometimes referred to as the fraternal fifteen," because of similarities in physical and chemical properties, the rare-earth elements actually are not so rare. This is attested by Fig. 1, which shows a dry lake bed in California that alone contains well in excess of one million pounds of two of die elements, neodymium and praseodymium. The world s largest rare earth body and mine near Baotou, Inner Mongolia, China is shown in Fig. 2. It contains 25 million tons of rare earth oxides (about one quarter of the world s human reserves. The term rare arises from the fact that these elements were discovered in scarce materials. The term earth stems from die tact that the elements were first isolated from their ores in the chemical form of oxides and that the old chemical terminology for oxide is earth. The rare-earth elements, also termed Lanthanides, are similar in that they share a valence of 3 and are treated as a separate side branch of the periodic table, much like die Actinides. See also Actinide Contraction Chemical Elements Lanthanide Series and Periodic Table of the Elements. 

Until 1964, monazite, a thorium-rare-earth phosphate, REPO4TI13 (P04)4, was the main source for the rare-earth elements. Australia, India, Brazil. Malaysia, and the United Slates are active sources. India and Brazil supply a mixed rare-earth chloride compound after thorium is removed chemically from monazite. Bastnasite, a rare-earth fluocarbonate mineral REFCO3. is a primary source for light rare earths. From 1965 to about 1985. an open-pit resource at Mountain Pass, California, has furnished about two-thirds of world requirements for rare-earth oxides. In the early... 

World resources of rare earths (x 10 metric tons of rare earths oxide REO) [3]. 

The amounts of the ores used for production of rare earth oxides are given in Table 1.14. The amounts of rare earth oxide produced in some parts of the world are given in Table 1.15. 

Owing to peculiar physical and chemical properties, rare-earth elements are used in various materials and consumer products, and thus, have become indispensable for our modem life. The world-wide rare-earth oxide consumption by the market sector in 2008 (Goonan, 2011) shown in Fig. 1 indicates that rare earths are used in glass industry, catalysts, neodymium magnets, battery alloys and other metallurgical additives, phosphors, ceramics, and other. According to the world mine production of rare earth in 2009 (Cordier, 2011),... 

Bastnasite (CeFCOs) - a fluorocarbonate of cerium containing 60-70% rare earth oxides (REO), including lanthanum and neodymium - is the world s major source of rare earths. Host rocks include carbonatite, dolomite breccia with syenite intrusives, pegmatite, and amphibole skam. Since 1985, the bastnasite production in China has increased very fast and has dominated the market from the 1990s to the present. 

Production World production of rare earths was estimated at 98,200 metric tons of equivalent rare earth oxides in 2002. The graph in Fig. 21.11 only shows the development of production up to 2006. China was by far the largest producer, with 90% of the world s total. Smaller amounts of ore came from the U.S.A. and other countries like India, Kazakhstan, Kyrgyzstan, Malaysia, Russia, and the Ukraine [37]. 

The total world reserves are estimated at 100 milHon tormes, counted as the content of rare earth oxide REO. Of this quantity China has 43, the former Soviet Union 19, the United States 13 and Australia 5 million tonnes. This large reserve is satisfactory compared to the actual consumption, although this may increase to an extent that is difficult to anticipate. On the other hand, undiscovered resources are thought to be very large. In addition, a high proportion of the rare earth metals used in modem society may appear as a workable scrap. It is estimated that as much as 30% of the large quantity of RE metals in magnets wiU be recovered and reused. 

Rare Earths are produced primarily from three ores, monazite, xenotime, and bastnasite. Monazite is a phosphate mineral of essentially the cerium subgroup metals and thorium -(light rare Earths, Th) P04. The composition of monazite is reasonably constant throughout the world, with almost 50% of its rare Earth content as cerium and most of the remaining 50% as the other members of the cerium subgroup. Xenotime, like monazite, is a rare Earth orthophosphate but contains up to 63% yttrium oxide and also a markedly higher propor-... 

About 25 000 tons of RE Metals - calculated as oxide - are currently consumed in the world per year. This quantity is divided among a dazzling variety of applications. In order to bring a certain systemization into this variety, these applications and possible applications have been reviewed from 3 different aspects from a historic development, from the special properties of the rare earths and from the degree of separation of the individual elements or grcfup of elements of the rare earth metal series. 

Period of First Industrial Usage. By iitprovement of this first discovery there arose the first industrial consunption of rare earths and the hour of birth of the rare earth industry in the year 1891, when Auer vcn Welsbach reported his patents for the Auer incandescent mantle v ch is conposed of 99 % thorium oxide and 1 % cerium oxide. Ihis light was sip>erior for decades to electric light. It was cheaper so that until the year 1935 approximately 5 billion incandescent mantles had been produced and consumed in the world. 

Americium was isolated first from plutonium, then from lanthanum and other impurities, by a combination of precipitation, solvent extraction, and ion exchange processes. Parallel with the separation, a vigorous program of research began. Beginning in 1950, a series of publications (1-24) on americium put into the world literature much of the classic chemistry of americium, including discussion of the hexavalent state, the soluble tetravalent state, oxidation potentials, disproportionation, the crystal structure(s) of the metal, and many compounds of americium. In particular, use of peroxydisulfate or ozone to oxidize americium to the (V) or (VI) states still provides the basis for americium removal from other elements. Irradiation of americium, first at Chalk River (Ontario, Canada) and later at the Materials Testing Reactor (Idaho), yielded curium for study. Indeed, the oxidation of americium and its separation from curium provided the clue utilized by others in a patented process for separation of americium from the rare earths. 

Although Rhone-Poulenc has given up direct upstream development after fruitless association with Dysan in magnetic supports and Siltec in silicon, it still believes it can use its know-how in rare earths to develop their electronics applications. Today, Rhone-Poulenc is the indisputable leader in rare earths, accounting for 40 percent of the world market. At its units in La Rochelle, France, and Freeport, Texas, it is capable of extracting from lanthanide sands the fourteen elements they contain. Over the last few years, samarium, for instance, has become essential for microelectronics to the same degree that europium and yttrium oxides already are for color television. 

There is a fertile, largely unexplored world of novel catalytic applications of rare-earth-containing mixed oxides. 

Pires, E.L., M. Wallau and U. Schuchardt, 1997, Selective oxidation of cyclohexane over rare earth exchanged zeolite Y, in 3rd World Congr. on Oxidation Catalysis, eds R.K. Grasselli, S.T. Oyama, A.M. Gaflhey and J.E. Lyons, Vol. 110 of Studies in Surface Science and Catalysis (Elsevier, Amsterdam) pp. 1025-1027. 

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