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Monazite sand deposits are prevalently of the monazite- composition. Typically, the lanthanides in such monazites contain about 45–48% cerium, about 24% lanthanum, about 17% neodymium, about 5% praseodymium, and minor quantities of samarium, gadolinium, and yttrium. Europium concentrations tend to be low, about 0.05%.
Lanthanum is rarely the dominant lanthanide found in the rare earth minerals, and in their chemical formulae it is usually preceded by cerium. Rare examples of La-dominant minerals are monazite-(La) and lanthanite-(La). [50] Production of Lanthanum from Monazite sand. The La 3+
The lanthanides that dissolved as a result of the acid treatment were subjected to solvent extraction, to capture the europium, and purify the other individual components of the ore. A further product included a lanthanide mix, depleted of much of the cerium, and essentially all of samarium and heavier lanthanides.
Lanthanites are frequently found as secondary minerals formed by the weathering of other minerals and occur as scales or tabular crystals. Originally identified at Bastnäs, Sweden, [9] they have subsequently been found in New Zealand, [10] Japan, [11] Madagascar, [12] Wales, [13] China, [14] France, [15] Germany, [16] Greenland, [17] Finland, [18] Canada, [19] Austria, [20] Romania, [21 ...
Dysprosium is obtained primarily from monazite sand, a mixture of various phosphates. The metal is obtained as a by-product in the commercial extraction of yttrium. In isolating dysprosium, most of the unwanted metals can be removed magnetically or by a flotation process.
The lighter (larger) lanthanides adopt a hexagonal 7-coordinate structure while the heavier/smaller ones adopt a cubic 6-coordinate "C-M 2 O 3" structure. [11] All of the sesquioxides are basic, and absorb water and carbon dioxide from air to form carbonates, hydroxides and hydroxycarbonates. [7] They dissolve in acids to form salts. [8]
The lanthanides obey the Oddo–Harkins rule – odd-numbered elements are less abundant than their even-numbered neighbors. Three of the lanthanide elements have radioactive isotopes with long half-lives (138 La, 147 Sm and 176 Lu) that can be used to date minerals and rocks from Earth, the Moon and meteorites. [88]
The product is then dried and leached with water, leaving the early lanthanide ions, including lanthanum, in solution. [41] The procedure for monazite, which usually contains all the rare earth, as well as thorium, is more involved. Monazite, because of its magnetic properties, can be separated by repeated electromagnetic separation.
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