Thorium crystal chemistry

Sigmon GE, Bums PC (2010) Crystal chemistry of thorium nitrates and chromates. J Solid State Chem 183 1604-1608... 

Crystal chemistry of thorium bismuthide. ThBi has a tetragonal crystal structure (with oo = 4.942 A, and co = 9.559 A) containing two thorium atoms and two bismuth atoms per unit cell. The density as determined... 

The uranium and thorium ore concentrates received by fuel fabrication plants still contain a variety of impurities, some of which may be quite effective neutron absorbers. Such impurities must be almost completely removed if they are not seriously to impair reactor performance. The thermal neutron capture cross sections of the more important contaminants, along with some typical maximum concentrations acceptable for fuel fabrication, are given in Table 9. The removal of these unwanted elements may be effected either by precipitation and fractional crystallization methods, or by solvent extraction. The former methods have been historically important but have now been superseded by solvent extraction with TBP. The thorium or uranium salts so produced are then of sufficient purity to be accepted for fuel preparation or uranium enrichment. Solvent extraction by TBP also forms the basis of the Purex process for separating uranium and plutonium, and the Thorex process for separating uranium and thorium, in irradiated fuels. These processes and the principles of solvent extraction are described in more detail in Section 65.2.4, but the chemistry of U022+ and Th4+ extraction by TBP is considered here. 

Coordination compounds of diphosphazane dioxides with uranyl or thorium ions were synthesized [475], The crystal structure of [U02(N03)2L1] [L, = Ph2P(0) N(Ph)P(0)Ph2] reveal the bidentate chelating mode of binding of the diphosphazane dioxide to these metals. The chemistry of other uranium organophosphorus and related compounds is described [476-479]. Some of the actinide complexes are presented in Table 5.16. 

Rapp RP and Watson EB (1986) Monazite solubihty and dissolution kinetics Implications for the thorium and light rare earth chemistry of felsic magmas. Contrib Mineral Petrol 94 304-316 Rapp RP, Ryerson FJ, Miller CF (1987) Experimental evidence bearing on the stability of monazite during crystal anatexis. Geophys. Res Letters 14 307-310... 

McCoy had always been interested in rare earth chemistry and had succeeded in separating some of them by fractional crystallization. He was also aware that the Lindsey Light and Chemical Company had a supply of residues containing rare earths that were left over after the thorium had been extracted from a feed stock. He also knew that europium could be reduced to the divalent state and as such was easily separable from the other rare earths by coprecipitating it with barium sulfate. 

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