Chloride calcium, direct oxide reduction

Direct Oxide Reduction. In DOR, calcium chloride is used as a solvent to dissolve the calcium oxide in the reaction ... 

Calcinm glectrowinning in piutniiium production. A potential application of inorganic membranes in radioactive waste treatment is in the industrially practiced direct oxide reduction process. In this process plutonium oxide is calciothermit y reduced to plutonium in the presence of calcium chloride according to the following reaction ... 

The effluent salt is the radioactively contaminated calcium chloride saturated with calcium oxide which can not be discarded as-is. Thus it is desirable to cathodically reduce calcium oxide to calcium which can then be recycled back to the direct oxide reduction process. The primary difficulty in obtaining a cathodic calcium deposit is due to the evolution of carbonaceous anodic gases which encourage various reverse reactions in the cell leading to loss of deposited calcium. 

Plutonium metal is prepared by two methods--direct reduction of the oxide by calcium (DOR)U,2J, and reduction of PuF by calcium in our metal preparation line (MPL)(3) (see Figure 1). In the DOR process, the plutonium contenF of the reduction slag is so low that the slag can be sent to retrievable storage without further processing. Metal buttons that are produced are no purer than the oxide feed and/or the calcium chloride salt. Los Alamos purifies the buttons by electrorefin-ing(4i,5 ), yielding metal rings that are > 99.96 percent plutonium. 

By reduction, it is possible to pass from nitrobenzene to aniline through the intermediate compounds nitrosobenzene and phenyl-hydroxylamine, and by oxidation in the reverse direction. It has been shown that nitrosobenzene and phenylhydroxylamine are formed in the electro-reduction of nitrobenzene, but it is impossible, at present, to effect some of the transformations indicated above in such a way that the reactions can be used as preparative methods. Some, however, can be used for this purpose. Phenylhydroxylamine, for example, is oxidized in the cold by potassium bichromate and sulphuric acid to nitrosobenzene, and is converted by reducng agents into aniline. In certain cases it is possible, by selecting the proper reagent, to effect the change indicated by two of the steps noted above. Phenylhydroxylamine is best prepared by treating with zinc dust a solution of nitrobenzene in dilute alcohol which contains a small amount of calcium chloride. 

Chen, G. Z., D. J. Fray, and T. W. Farthing. Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride. Nature 407 (2000) 361-364. First description of the FFG-Cambridge method—possibly game-changing procedure for reducing metal oxides. 

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