Bastnasite lanthanum

Lanthanum is found in rare-earth minerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25 percent and 38 percent respectively. Misch metal, used in making lighter flints, contains about 25 percent lanthanum. 

As with other rare-earth metals, except for lanthanum, europium ignites in air at about 150 to I8O0C. Europium is about as hard as lead and is quite ductile. It is the most reactive of the rare-earth metals, quickly oxidizing in air. It resembles calcium in its reaction with water. Bastnasite and monazite are the principal ores containing europium. 

Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

The main ore in which lanthanum is found is monazite sands, and it is also found in the mineral bastnasite. Monazite sands contain all of the rare-earth elements as well as some elements that are not rare-earths. Its ores are found in South Africa, Australia, Brazil, and India and in California, Florida, and the Carolinas in the United States... 

The element was discovered by Klaproth in 1803 and also in the same year by Berzelius and Hisinger. It is named after the asteroid Ceres. Cerium is found in several minerals often associated with thorium and lanthanum. Some important minerals are monazite, aUanite, cerite, bastnasite, and samarskite. It is the most abundant element among aU rare-earth metals. Its abundance in the earth s crust is estimated to be 66 mg/kg, while its concentration in sea water is approximately 0.0012 microgram/L. 

Lanthanum is most commonly obtained from the two naturally occurring rate-earth minerals, monazite and bastnasite. Monazite is a rare earth-thorium phosphate that typically contains lanthanum between 15 to 25%. Bastnasite is a rare earth-fluocarbonate-type mineral in which lanthanum content may vary, usually between 8 to 38%. The recovery of the metal from either of its ores involves three major steps (i) extraction of all rare-earths combined together from the non-rare-earth components of the mineral, (ii) separation or isolation of lanthanum from other lanthanide elements present... 

Extraction of lanthanum from monazite is discussed below first, followed by that from bastnasite. 

When lanthanum is produced from the mineral bastnasite, all processes except ore extraction discussed above are the same. The mineral is crushed and concentrated by flotation process. This is followed by treatment with dilute HCl, which converts lanthanum and the rare-earths contained in the mineral into their chlorides. Calcination in air results in rare-earth oxides. 

From this early availability and use of mischmetal grew a demand for bastnasite ore. In these alloys, about one-half of the present rare earths are cerium. In the mid-to-late sixties, a more economical source of cerium was introduced which was, in essence, a concentrate from which the lanthanum had been removed. This material allowed for the production of alloys whose rare earth concentration was about 90% cerium. These rare earthbearing materials have the approximate analyses shown in Table I and are now used commercially, with the high cerium source predominating in the United States. 

There are in fact fourteen, and they became known as the rare earths - a misnomer, for some are not particularly rare at all, and they are metals, not earths . A better name is the lanthanides, since they all follow after lanthanum in the Periodic Table. They form an entirely new group, which cannot economically be fitted into Mendeleyev s scheme and is usually depicted as floating freely below it. The lanthanides are, broadly speaking, all rather similar in their chemical behaviour, which is why they were so hard to separate. They are found in minerals such as monazite and bastnasite, the main sources of which are in China and the USA. 

Mischmetal is produced commercially by electrolysis, The usual starting ingredient is the dehydrated rare earth chloride produced from monazite or bastnasite. The mixed rare earth chloride is fused in an iron, graphite, or ceramic crucible with the aid of electrolyte mixtures made up of potassium, barium, sodium, or calcium chlorides. Carbon anodes are immersed in the molten salt. As direct current flows through the cell, molten mischmetal huilcls up in the bottom of the crucible. This method is also used to prepare lanthanum and cerium metals. 

A fraction of Ce, La. Nd and Pr derived from bastnasite or monazite is a typical feedstock in the recovery process of cerium on a commercial scale. Separation of the rare-earth elements may be achieved by splitting the mixed rare-earth elements into a cerium/lanthanum and didymium (Nd/Pr) fraction first. The cerium/lanthanum fraction may be used as a further feedstock in a second extraction stage and will yield high pure cerium and lanthanum solution respectively. Cerium can then be precipitated as. for example, an oxalate or a carbonate which may be used as precursor for cerium derivatives. 

Cerium is the most abundant member of the lanthanide, or rare earth, elements. It has two stable valence states, Ce (cerous) and Ce " (ceric). It is found as a trace element in several minerals, but only two, bastnasite, LnFCOs, and monazite, (Ln, Th)P04 (where Ln = a lanthanide element, such as lanthanum, praseodymium, neodymium, or cerium), which are approximately 30 percent and 22 to 25 percent cerium, respectively, are the principal sources of this element. 

Monazite and bastnasite are the principal lanthanum ores, in which lanthanum occurs together with other members of the rare earth elements or the lanthanides. It can be separated from the other rare earths by ion... 

The world s resources of rare earth metals lie mainly in deposits of bastnasite in China. The chart below shows that mine production of the ore from China dominates the world s output. Bastnasite is a mixed metal carbonate fluoride, (M,M. ..)C03F. The composition varies with the source of the mineral, but the dominant component is cerium ( 50%), followed by lanthanum (20-30%), neodymium (12-20%) and praseod5mium (w5%). Each of the other rare earth metals (except for promethium which does not occur naturally) typically occurs to an extent of < 1 %. Monazite,... 

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. 

Obtained from Lanthanum mainly is obtained from lanthanum-rich monazite and bastnasite. Other lanthanum-bearing minerals include allanite and ceiite. It is mined in the USA, China, Russia, Australia, and India [43]. 

Lanthanum — (Gr. lanthanein, to lie hidden). La at. wt. 138.9055(2) at. no. 57 m.p. 918°C b.p. 3464°C sp. gr. 6.145 (25°C) valence 3. Mosander in 1839 extracted a new earth lanthana, from impure cerium nitrate, and recognized the new element. Lanthanum is found in rare-earth minerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25 and 38%, respectively. Misch metal, used in making lighter flints, contains about 25% lanthanum. Lanthanum was isolated in relatively pure form in 1923. Ion-... 

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