Rare earth reserves

Commercial mining of rare-earth reserves began ia the late 1800s. Mona2ite was the principal rare-earth source up until 1965. Thereafter bastnaesite production exceeded mona2ite production and as of 1992 bastnaesite, which is the world s principal source of rare earths, constituted 65% of world output of rare-earth minerals (see Table 5). In addition to the conventional ores, there are several other rare-earth resources having a low level of iadustrial production. 

Bastnasite LnFCOs Monazite (Ln, Th)P04 (richer in earlier lanthanides) Xenotime (Y, Ln)P04 (richer in later lanthanides). In addition to these, there are Chinese rare earth reserves which amount to over 70% of the known world total, mainly in the form of the ionic ores from southern provinces. These Chinese ion-absorption ores, weathered granites with lanthanides adsorbed onto the surface of aluminium silicates, are in some cases low in cerium and rich in the heavier lanthanides (Longnan) whilst the Xunwu deposits are rich in the lighter metals the small particle size makes them easy to mine. The Chinese ores have made them a leading player in lanthanide chemistry. 

In recent years, the characteristics of the rare earth market place have become a concern. The United States currently has 13 percent of the world s rare earth reserves and was the largest supplier of rare earth metals from about 1965 until 1985, when China, which owns 48 percent of the world reserves, entered the world market. China now supplies 97 percent of the rare earth needs worldwide. In 2010, China shook up global rare earth markets when it cut off rare earth shipments to Japan for a month because of a diplomatic dispute. The power of one nation to essentially control rare earth availabihty to all other nations is seen by many as a serious issue. 

TABLE II World Rare Earth Reserves and Reserve Base ... 

The chemical similarities of the natural REE (which excludes Pm) results in their universal occurrence in all rare earth minerals. The rare earths have a valence of three, are strongly electropositive and have little tendency to hydrolyze. Their strong affinity for both oxygen and phosphate results in the tendency for rare earth minerals to occur as phosphate complexes. In table 3 the major rare earth minerals, their usual form and the abundance of the REE in them are listed (Moeller 1963). Table 4 indicates known rare earth reserves. 

The uranium ore from Elliot Lake, Canada, contains yttrium and lanthanides (see Uranium and uranium compounds). In the Jiangxi province of the People s Repubhc of China a large reserve of a rare-earth-containing clay contains over 1,000,000 t of REO. This ore is characterized by having a low cerium content (<5%) but a high content in samarium, europium, terbium, and yttrium compared to the main base REO ores (Table 6). ... 

Gadolinite and bastnasite fron Sweden served at first as raw material for the rare earth eloivents and thorium. Later it was necessary to seek new raw materials and the so-called "Carolina sand" was found in the USA, a monazite v ch oociorred there in certain gold-panning areas. Finally a nearly ine diaustible reserve of monazite was discovered in Brazil v ch guaranteed raw material supplies far into the future. 

Co. of California. Proven orebody reserves at the end of December 1978 were 365,000 metric tons, with indicated reserves of over 3 million metric tons of rare earth oxide (REO). Current mine production capacity is 27,000 metric tons per year of bastnaesite concentrate produced in 3 grades a 60% REO unleached concentrate, a 70% REO leached concentrate (SrO and CaO removed), and a 90% REO calcined concentrate (CO2 removed). In 1977, shipments totaled 13,521 metric tons of contained REO. Polishing compounds consumed approximately 10% of this production. 

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. 

Handbook on the Physics and Chemistry of Rare Earths, Vol. 38 2008 Elsevier B.V. ISSN 0168-1273, D01 10.1016/S0168-I273(07)38002-1 All rights reserved... 

The lanthanides (Ln) include lanthanum (La) and the following fourteen elements—Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu— in which the 4f orbitals are progressively filled. These fifteen elements together with scandium (Sc) and yttrium (Y) are termed the rare-earth metals. The designation of rare earths arises from the fact that these elements were first found in rare minerals and were isolated as oxides (called earths in the early literature). In fact, their occurrence in nature is quite abundant, especially in China, as reserves have been estimated to exceed 84 x 106 tons. In a broader sense, even the actinides (the 5f elements) are sometimes included in the rare-earth family. 

The world reserves of rare earths are summarized in Table 1.4. The reserve base encompasses current economic reserves, marginally economic reserves and sub-economic reserves. The locations of the major rare earth deposits in the world are depicted in Fig. 1.1. 

The present title consists of twelve chapters. The first chapter is an introduction covering definition, classification, properties, world reserves, methods of processing from ores, methods of separation both classical and modem, and analytical chemistry of rare earths, including classical and modem methods. 

The rare earths (RE) are actually far from rare.6 The known reserves are more than 84 x 106 tons, a 2300 year supply at the present rates of consumption. Even the scarcest one, thulium, is more common than Bi, As, Cd, Hg, or Se. The largest reserves (51%) are in mainland China other major deposits are in the USA (15%), Australia (6%), and India (3%). 

Current estimates of the available reserves and further resources of uranium and thorium, and their global distribution, are shown in Figs. 5.44-5.50. The uraruum proven reserves indicated in Fig. 5.44 can be extracted at costs below 130 US /t, as can the probable additional reserves indicated in Fig. 5.45. Figure 5.46 shows new and unconventional resources that may later become reserves. They are inferred on the basis of geological modelling or other indirect information (OECD and IAEA, 1993 World Energy Council, 1995). The thorium resource estimates are from the US Geological Survey (Hedrick, 1998) and are similarly divided into reserves (Eig. 5.47), additional reserves (Fig. 5.48) and more speculative resources (Fig. 5.49). The thorium situation is less well explored than that of uranium the reserves cannot be said to be "economical", as they are presently mined for other purposes (rare earth metals), and thorium is only a byproduct with currently very limited areas of use. The "speculative" Th-resources may well have a similar status to some of the additional U-reserves. 

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