Neodymium extraction system

Study of membrane extraction processes is a matter of primary importance for intensive development of separation and concentration methods of different nature substrates, especially such valuable ones as rare and scattered metals. The imique properties of rare earth metals (REM) allow using them in different realms of modem science and technology when making selective catalysts, magnets (samarium and neodymium), optical systems, luminophors, and ceramic capacitors. REMs are used in metallurgy for production of special cast iron grades, steel, and nonferrous metals alloys. REM additives increase quality of metallurgical products improve their properties, particularly shock resistance, viscosity, and corrosion resistance. Such materials are used primarily in aerospace industry. Extraction of REM from minerals is a complex process. 

In the DMDBTDMA-alkane system (37, 140), the third phase is a gel when neodymium nitrate or thorium nitrate are extracted at high concentration, but... 

Osmium is of great interest to mantle geochemists because, in contrast with the geochemical properties of strontium, neodymium, hafnium, and lead, all of which are incompatible elements, osmium is a compatible element in most mantle melting processes, so that it generally remains in the mantle, whereas the much more incompatible rhenium is extracted and enriched in the melt and ultimately in the crust. This system therefore provides information that is different from, and complementary to, what we can learn from... 

Beyond the broad major-element constraints afforded by seismic imaging, the abundance of many trace elements in the mantle clearly records the extraction of core (Chapters 2.01 and 2.15) and continental crust (Chapter 2.03). Estimates of the bulk composition of continental cmst (Volume 3) show it to be tremendously enriched compared to any estimate of the bulk Earth in certain elements that are incompatible in the minerals that make up the mantle. Because the crust contains more than its share of these elements, there must be complementary regions in the mantle depleted of these elements—and there are. The most voluminous magmatic system on Earth, the mid-ocean ridges, almost invariably erupt basalts that are depleted in the elements that are enriched in the continental crust (Chapter 2.03). Many attempts have been made to calculate the amount of mantle depleted by continent formation, but the result depends on which group of elements is used and the assumed composition of both the crust and the depleted mantle. If one uses the more enriched estimates of bulk-continent composition, the less depleted estimates for average depleted mantle, and the most incompatible elements, then the mass-balance calculations allow the whole mantle to have been depleted by continent formation. If one uses elements that are not so severely enriched in the continental cmst, for example, samarium and neodymium, then smaller volumes of depleted mantle are required in order to satisfy simultaneously the abundance of these elements in the continental cmst and the quite significant fractionation of these elements in the depleted mantle as indicated by neodymium isotope systematics. 

In this section mantle evolution curves are presented for neodymium (Nd), hafnium (Hf), lead (Pb) and osmium (Os) isotopes. A summary of these isotopic systems is given in Text Box 3.2. Earlier studies based upon the study of Sr isotopes in the mantle (e.g. Bell et al., 1982) are now known to be unreliable because of its high geochemical mobility (Goldstein, 1988). The significance of the mantle evolution curves described here is that they demonstrate that the mantle does not operate as an isolated system but that it has evolved in its composition over time, in response to core formation, crust extraction, and the recycling of crustal material. 

Austrian scientists discovered three elements tellurium (1782), praseodymium (1885), and neodymium (1885). Danish scientists discovered aluminium (1825) and hafnium (1923) one element (ruthenium) was discovered in Russia in 18. But Russian scientists extracted many newly discovered elements from natural minerals and studied their properties (platinum metals, chromium, strontium). Though for a variety of reasons Russian chemists did not discover many new elements one should not forget that the periodic system of elements was developed by the great Russian chemist D. Mendeleev and this task was much more difficult than to discover a few new elements. 

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