Trivalent thorium solution studies

The authors have studied the dissolution of thorium phosphate diphosphate (TPD) with and without trivalent actinides they also studied a solid solution of Th(IV)/Pu(IV) phosphate diphosphate. The experiments consist of leaching studies where the rate of dissolution has been measured as a function of pH. This study does not provide any information on the solubility product of TPD. There is information on estimated equihb-rium constants for MP04(s) phases, where M = Am, Cm, Ce and Pr. These are secondary phases formed in the leach system. 

Triple orthovanadates containing a divalent cation, trivalent rare earth, and tetravalent thorium or cerium, have been studied by Nabar et al. (1981 and 1983). The samples were prepared by mixing soluble compounds of the corresponding elements in water, evaporating the solution and heating at SOO C. The compounds MRTh(V04)3, where M = Ca, Cd, crystallize with the tetragonal zircon structure and those where M = Ba with the monoclinic monazite structure. Strontium and lead compounds show dimorphism (Nabar and Mhatre, 1982). 

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