RESOURCESSignificant new resources are the ion-adsorption ores processed by China. These werecreated by the weathering of primary granitic-type rock followed by the capture of soluble Lnspecies by adsorption on clays. Ideal climatic conditions for this process evidently occurred insouthern china, especially Jiangxi province, where there are many such deposits. The weatheringprocess modifies the proportions of the various lanthanides present and can reduce the Ceriumcontent compared to the source rock. These ores, with compositions dependent on location, arerelatively rich in Y and the mid-Ln's such as Eu Sm and Gd, and, although of overall low-Lncontent, are easily processed. They now supply a major portion of the world's yttrium and heavylanthanides.The mineral, Eudialyte, an acid-soluble calcium-zircon silicate, is also a potential Yttriumsource. Significant deposits have been identified in Russia, U.S.A. (New Mexico), U.S.A.,Greenland and elsewhere. Deposits of several other minerals, such as Brannerite, Gadolinite andEuxenite, particularly in Canada and Australia, have been examined as potential yttrium (andlanthanide) sources. These minerals contain a variety of large polyvalent ions, among them yttriumand some heavy lanthanides. The complexity of the ore bodies and of the mineral compositionshowever gives major processing problems. A simple physical route, or an inexpensive chemicalcrack, to a good grade concentrate is difficult to find.World reserves have been estimated as ≈85 million tonnes[7], more than 1,000 times currentannual consumption. Total production of lanthanide (rare earth) oxides (LnO's) in 1991was≈70,000 tons, 35 % from China and 35 % from the United States, with the bulk of the world'ssupply of Ln's being met by the mineral Bastnasite. In that year, of China's ≈25,000 tons LnO, only900 tons came from monazite whereas 6,100 were apparently derived from the new"ion-adsorption" source. Direct comparison between production and consumption quantities isobscured by stockpiling of partially processed ores.The major factor in world markets during the '80's has been the development ofion-adsorption ores in China and a drive by the chinese to increase exports in order to obtainforeign currency.[8] They have increased production by an order of magnitude and become themajor supplier to many markets outside the U.S. in particular to Japan. The steady productionincrease by China, and their increased overseas marketing with province competing againstprovince, caused significant declines in the price of high-purity materials and major problems forthe market-economy producers.[7] Rare Earth Metals, J.B.Hedrick, U.S.Dept Interior, Mineral Commodity Summaries, 1991, 12835
[8] The Rare Earth Industry: A World of Rapid Change, P.Falconnet, J. Alloys Comp., 1993, 192, 11436
- Page 2 and 3: ALANTHANIDELANTHOLOGYPart II, M - Z
- Page 6 and 7: Compounds of the perovskite, ABO 3
- Page 8 and 9: METALSThe lanthanides, when prepare
- Page 10: METALSMetallo-thermic oxide-reducti
- Page 13 and 14: MONAZITEMonazite, a light-lanthanid
- Page 15 and 16: NEODYMIUMNeodymium is the third mos
- Page 18 and 19: [2] Preparation, Phase Equilibria,
- Page 20 and 21: NOMENCLATURE58 - 71; the term is in
- Page 22 and 23: OXALATESAddition of oxalic acid, or
- Page 24 and 25: OXIDESCalcination in air for the th
- Page 26 and 27: OXIDESFurthermore oxides with Ln IV
- Page 28 and 29: OXYCHLORIDESThermal decomposition o
- Page 30 and 31: OXYSULFIDESAll the elements of the
- Page 32 and 33: PEROVSKITESA very wide range of mat
- Page 34 and 35: PHOSPHATESThe LnPO 4 compounds can
- Page 36 and 37: PRASEODYMIUMtransport of Pr happens
- Page 38 and 39: RESOURCESFor significant resources
- Page 42 and 43: SAMARIUMSamarium metal is made dire
- Page 44 and 45: SILICATESWithin the binary Ln 2 O 3
- Page 46 and 47: SOLVENT EXTRACTIONSome text books s
- Page 48 and 49: SULFATESLanthanide sulfates can be
- Page 50 and 51: SULFIDESThe thermochernistry of CeS
- Page 52 and 53: THULIUMThulium, the rarest of the "
- Page 54 and 55: TITANATES, TITANIUM DIOXIDELanthani
- Page 56 and 57: YTTERBIUMIn broad chemical behavior
- Page 58 and 59: YTTRIUMCompoundIdealFormulaFormula
- Page 60 and 61: YTTRIUM OXIDEThe very stable oxide,
- Page 62 and 63: YTTRIUM OXIDEThe widespread introdu
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