Oxides direct reduction

Direct oxide reduction (DOR) is presently being tested on production equipment. Eventually, it is hoped to eliminate the fluorination and bomb reduction processes and replace them with DOR. 

Electrorefining. Impure plutonium metal from MSE and Direct Oxide Reduction (DOR) is sent to an electrorefining operation (J3). In plutonium electrorefining, impure plutonium... 

Direct Oxide Reduction. Implementation of the DOR process into production Ts currently underway. Plutonium oxide from foundry operations, hydriding, and other sources is calcined in... 

The following pages will describe several examples of pyrochemical processing as applied to the recycle of plutonium, and will briefly review the fundamental chemistry of these processes. We shall review the conversion of plutonium oxide to plutonium metal by the direct oxide reduction process (DOR),the removal of americium from metallic plutonium by molten salt extraction (MSE), and the purification of metallic... 

The use of this direct oxide reduction process is replacing fluoride reduction as it eliminates neutron exposure to operating personnel (alpha particles from plutonium decay have sufficient energy to eject neutrons from fluorine by the a,n reaction) and eliminates reduction residues which require subsequent recovery. 

The reaction is carried out under an inert atmosphere in an open crucible at approximately 830°C. Figure 1 shows typical equipment used for direct oxide reduction. Vitrified magnesium oxide ceramic is commonly used as a container material, but tungsten and tantalum can also be used(3). If the latter are used, CaF2 is added to lower the temperature needed to liquify... 

Although the exact chemical mechanism for the direct oxide reduction reaction has not yet been fully characterized, it has been well established that the reaction goes to completion when excess calcium is present, sufficient CaCl2 is available to dissolve the CaO produced, and adequate stirring is used. As calcium metal is soluble to about 1 wt% in CaC12 at 835°C, excess Ca insures that the reaction is driven to completion by mass-action effects. 

A. Process Schematic. A schematic of the main process sequence for the conversion of plutonia scrap to high-purity metal is shown in Figure 2. Plutonia scrap is fed to both the direct oxide reduction (DOR) process and the plutonium tetrafluoride production/ reduction process. 

Direct Oxide Reduction. In DOR, plutonia is reduced with calcium metal to form plutonium metal and calcium oxide.2 3 The reaction takes place in a CaCl2 solvent which dissolves the calcium oxide and allows the plutonium metal to coalesce in the bottom of the crucible. 

Figure 4. Direct oxide reduction metal product with residues.

The skull metal and oxide are first completely burned to oxide by heating in air to 400-500°C. The plutonium metal spontaneously burns and is collected as a green Pu03 powder. This oxide is recycled back as feed for Direct Oxide Reduction. This process is normally 100% efficient with only a small plutonium residue showing up in items such as clean-up rags. 

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

Direct oxidation, of H2S, 23 616—617 Direct oxidation catalyst, 23 616—617 Direct oxidation ethylene oxide manufacture, 10 641—648 Direct oxidation tail gas process, 23 619 Direct oxide reduction (DOR) process, 19 676-677... 

Direct oxide reduction by Ca metal (Section II,A) in a molten CaClj solvent system 80) has been used for kilogram-scale production of Np metal. The product metal is further purified by electrorefining (Section... 

The method of choice for kilogram-scale preparations of Np metal is direct oxide reduction by Ca metal in a molten CaCl2 solvent system as described above, followed by electrorefining. This metal can be further refined by levitation melting (Section III,A). 

Diquat insecticides, 34 1-2 Direct exchange, 38 426 magnetic orbitals, 38 435 Directly bonded complexes, 21 202-207 Direct oxide reduction, in actinide metal preparation, 31 6-7, 21-22, 25 apparatus, 31 29... 

This technique of forming semiconducting films by direct oxidation-reduction is used to grow highly microcrystalline films directly on the copper or silver substrate. These films show a metallic sheen and can be grown to a thickness of 10 ym in a... 

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