China 
Africa 
Explore chapters and articles related to this topic
Generation and Composition of Various Metal-Containing Industrial Wastes
Published in Hong Hocheng, Mital Chakankar, Umesh Jadhav, Biohydrometallurgical Recycling of Metals from Industrial Wastes, 2017
Hong Hocheng, Mital Chakankar, Umesh Jadhav
For economic reasons, the La present in AB5 is often replaced by a rare earth alloy known as Mischmetal (Baddour-Hadjean et al. 2003). Mischmetal is a mixture of rare earth elements, usually composed mainly of Ce, associated with La, Nd, Pr, and others, in proportions in which they occur naturally in minerals (Gschneidner et al. 1990). Regarding the charge and discharge efficiency and durability of the different alloys cited, only AB5 and AB2 have practical applications.
Structural Aspects of Skutterudites
Published in Ctirad Uher, Thermoelectric Skutterudites, 2021
While proposals to fill the voids with more than a single type of filler (Nolas et al. 1998), and successful attempts to realize them in experiments have been made earlier (Chen et al. 2001a, Bérardan et al. 2003, 2005a, and Lu et al. 2005), the impact of seeing the actual frequency range one can cover with different fillers has stimulated many new efforts to double and even triple fill the skutterudite structure. With carefully selected filler species to cover a wide range of resonant frequencies, numerous studies have shown that such multifilling is superior to single filling and is able to reduce the thermal conductivity to a much greater extent. Moreover, the power factor is often better optimized with multifilling rather than with a single filler. Thus, with single-filled skutterudites, the highest ZT values hover around unity with occasional reports of ZT ~ 1.2, such as in the case of Ba0.3Co3.95Ni0.05Sb12 (Dyck et al. 2002), and In0.25Co4Sb12 (T. He et al. 2006). Judiciously chosen double-filler species can raise the ZT to values in the range 1.3–1.4. Particularly effective double-filling combinations are Ba+Yb (Shi et al. 2008), Ba+Ce (Bai et al. 2009), Ba+In (Zhao et al. 2009), and In+Ce (Li et al. 2009). To maximize the degradation of the lattice thermal conductivity, even several triple-filling combinations of elements, aiming to cover a broad range of localized vibrational frequencies, have been explored (Graff et al. 2011), Zhang et al. 2009), Rogl et al. 2011), and Ballikaya et al. 2012). Among these, Ba0.08La0.05Yb0.04Co4Sb12 achieved the record high ZT = 1.7 at 850 K (Shi et al. 2011). I also mention the filling of skutterudites with the misch-metal by Yang et al. (2007b), an alloy of rare-earth elements in their naturally occurring proportions, dominated by Ce, La, Pr, and Nd with trace impurities of Fe, Si, Al, and O. Misch-metal is an intermediate product in the preparation of all high-purity rare-earth elements, and the content of rare-earths is some 95.5%. Finally, impressive values approaching ZT ~ 2 were obtained by filling the skutterudite cages with didymium, an alloy consisting of 4.76 mass% Pr and 95.24 mass% Nd, and applying severe plastic deformation using high-pressure torsion (Rogl et al. 2010, 2014). Full discussion on these is given in the thermal transport section of the book.
Recovery and Recycling of Cerium from Primary and Secondary Resources- a Critical Review
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Cerium is the light group rare earth element with atomic number 58 and atomic weight 140.116. Cerium is the most common lanthanides found in the Earth’s crust, where it comprises about 0.0046% by weight (Dahle and Arai 2015). There are no ores, which contains only cerium as the metal component. It is found in minerals that include all the other lanthanide elements. The current production of CeO2 is about 54,400 t (32% of REE oxides) (Borra et al. 2017) and its market is expected to register a CAGR of around 8%, during the forecast period of 2019–2024. It is found in many minerals including monazite, bastnäsite, gadolinite, fergusonite, samarskite, xenotime, yttrocerite, cerite and allanite (also known as orthite), etc. Monazite [(Ce, La, Y, Th)PO4] and Bastnäsite [(La, Ce)FCO3] are presently the two more important sources of cerium (Shwe, Soe and Lwin 2008). Table 1 lists the predominant cerium minerals found in various locations along with their composition. Cerium oxides and other cerium compounds are used in catalytic converters and larger-scale equipment to reduce sulfur oxide emissions. Cerium is a diesel fuel additive for micro-filtration of pollutants and promotes more complete fuel combustion for more energy efficiency. It is one of the components of misch metal, which is used extensively in the manufacturing of pyrophoric alloys, making aluminum alloys and in some irons and steels. (Shwe, Soe and Lwin 2008). Cerium is used as a catalyst in automobile and nuclear chemistry, NiMH batteries, FCC catalyst, autocatalyst, petroleum refining, polishing agents, as a component in glass (Habashi 2013). It is also used in car coatings, CFLs, LEDs, LCD backlights, plasma screens, which later becomes a secondary source of cerium recovery (Borra et al. 2017).