Mixer settler electrolytic

In addition, solvent extraction is appHed to the processing of other metals for the nuclear industry and to the reprocessing of spent fuels (see Nuclearreactors). It is commercially used for the cobalt—nickel separation prior to electrowinning in chloride electrolyte. Both extraction columns and mixer-settlers are in use. 

Figure 4. KFK electrolytic contactors a. mixer settler, h. pulsed column.

The parallel electrolytic reduction developments at Karlsruhe appear to have concentrated initially more on the reduction of Pu and U in electrode-equipped mixer-settlers in which the reduction occurred largely in the settled aqueous phase rather than in a heterogeneous mixture. It was determined that a separating membrane may njt be necessary because of the redox potentials in the U - U5 - U6 system and the absence of gaseous products at the electrodes which could lead to explosive mixtures. A pulsed column, with internals quite different from those of Allied Chemical s electropulse column, was eventually developed and successfully tested (15,26) (Fig. 4). 

In 1968, an electrolytic reduction process was proposed by A. Schneider and A. L. Ayers (6) to circumvent the above disadvantages. A research program was carried out in the Allied Chemical Corporation s laboratories during the years 1968 to 1972 to develop the process and equipment. The work resulted in the development of the Electropulse Column ( 7) for the continuous (differential) electrolytic uranium-plutonium partition process, which was later scaled up, fabricated, and installed in the Allied-General Nuclear Services reprocessing plant at Barnwell, South Carolina. About the same time, a stagewise electrolytic uranium-plutonium partition process was tested on a mini mixer-settler unit in Germany. (8)... 

Figure 14. Schematic of electrolytic mixer settler I, mixing chamber 2, settling chamber 3, anode cell 4, Ft anode 5, Ti cathode plate 6, insulator 7, separator.

Solvent extraction Contactors Pulse columns electrolytic Centrifugal + Mixer-settlers Pulse and Pulse columns Centrifugal... 

The smallest element of an isotope separation plant that effects some separation of the process material is called a separating unit. Examples of a single separating unit are one stage of a mixer-settler, one plate of a distillation column, one gas centrifuge, one calutron, or one electrolytic cell. 

A similar process has been devised by the U.S. Bureau of Mines (8) for extraction of nickel and cobalt from United States laterites. The reduction temperature is lowered to 525°C and the hoi ding time for the reaction is 15 minutes. An ammoniacal leach is also employed, but oxidation is controlled, resulting in high extraction of nickel and cobalt into solution. Mixers and settlers are added to separate and concentrate the metals in solution. Organic strippers are used to selectively remove the metals from the solution. The metals are then removed from the strippers. In the case of cobalt, spent cobalt electrolyte is used to separate the metal-containing solution and the stripper. MetaUic cobalt is then recovered by electrolysis from the solution. Using this method, 92.7 wt % nickel and 91.4 wt % cobalt have been economically extracted from domestic laterites containing 0.73 wt % nickel and 0.2 wt % cobalt (8). 

---