Classification of uranium

The world s largest and highest-grade uranium deposits occur in metamorphic rocks. An extensive review of the classification of uranium deposits was given by Ruzicka. His classification of uranium vein deposits was subdivided into five types, based mainly on mineralogy. 

Jones C. A. A classification of uranium deposits in sedimentary host rocks. In NURE uranium geology symposium (Grand Junction, Colo. Bendix Engineering Corporation, 1978), 23-8. 

Mathews G. W. A classification of uranium deposits in and related to plutonic igneous rock. Reference 15, 15-21. 

The remaining exceptions concern the lanthanide series, where samarium at room temperature has a particular hexagonal structure and especially the lower actinides uranium, neptunium, and plutonium. Here the departure from simple symmetry is particularly pronounced. Comparing these three elements with other metals having partly filled inner shells (transition elements and lanthanides), U, Pu, Np have the lowest symmetry at room temperature, normal pressure. This particular crystallographic character is the reason why Pearson did not succeed to fit the alpha forms of U, Pu, and Np, as well as gamma-Pu into his comprehensive classification of metallic structures and treated them as idiosyncratic structures . Recent theoretical considerations reveal that the appearance of low symmetries in the actinide series is intimately linked to the behaviour of the 5f electrons. 

The similarities are of the following kinds. First, neither classification system includes a general class of exempt waste. Second, neither classification system is comprehensive, because the classification system for radioactive waste distinguishes between fuel-cycle and NARM waste and the classification system for hazardous chemical waste excludes many potentially important wastes that contain hazardous chemicals. Third, any waste must be managed and disposed of in a manner that is expected to protect public health and the environment. In addition, the approach to disposal of hazardous chemical waste under RCRA, which emphasizes monitoring of releases from disposal facilities and an intention to maintain institutional control over disposal sites for as long as the waste remains hazardous, is applied to disposal of uranium or thorium mill tailings under AEA. 

UPt3 belongs to the class of uranium-based heavy-fermion compounds. That classification is due to the large value for y in the expression for the specific heat at low temperature ... 

Another major classification of the elements in terms of the periodic table is shown in Figure 1.7. Three areas are defined and named the main group elements, the transition elements, and the inner transition elements. The main group elements are the simplest to learn abont, and they will be stndied first. The transition elements inclnde some of the most important elements in onr everyday lives, such as iron, nickel, chrominm, zinc, and copper. The transition elements are often divided into four rows of elements, called the first, second, third, and fourth transition series. The elements of the fourth transition series except for actinium (Ac), and those of the main group elements above 112, are artificial they are not found in nature. The two inner transition series fit into the periodic table in periods 6 and 7, right after lanthanum (La) and actinium (Ac), respectively. The inner transition elements include a few important elements, including uranium and plutonium. The first series of inner transition elements is called the lanthanide series, after lanthanum, the element that precedes... 

Arden et al. (A7) used the jigged-bed ion exchange technique for the extraction of uranium from acid-leached pulps. This method treats de-sandcd pulp containing 2(M0% by weight of solids with the -1-300 mesh particles removed by classification in single hydrocycloncs. The volume of the slime pulp is 1.2-2.0 times the volume of the leach solution compared to 2-3 times if conventional filtration is used. 

Until vciy recently only ninety-two elements were recognized and the periodic classification ended with the element uranium. In 1940 McMii.i.an and Abelson showed that bombardment of uranium witli neutrons led to the production of an isotope of a new clement, neptunium, of atomic number 93. Diis isotope whu h has a half life period of 2 3 days,... 

Economic Considerations and the Classification of Ore Deposits The Example of Vanadium-Uranium... 

It is worthy to note that the Chemyaev-Schelokov and Suglobov rows can be used not only in classification of experimental data but also in prediction of the interplay between composition and stmcture for many different uranyl complexes. However, as to our knowledge, there were no attempts made in understanding chemical factors that determine coordination number of uranium in uranyl complexes (i.e. 5, 6, 7, or 8). However, this question is of primary importance for us and was considered in detail in [13, 14]. In these works, we have used a new stereoatomic model of crystal stmctures which we shall briefly outline in the following section. 

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