PROCESS FOR CHANGING THE VALENCE OF A METAL OF VARIABLE VALENCE IN AN ORGANIC SOLUTION

摘要

1301376 Electrolysing polyvalent metals ALLIED CHEMICAL CORP 13 April 1970 [14 April 1969] 17493/70 Heading C7B [Also in Division G6] The valency of one or more polyvalent metals, e.g. U, Pu, Np, is changed by passing an electric current through a dispersion of an organic solution comprising the metal(s) and preferably an alkyl phosphate and a hydrocarbon diluent, with an immiscible aqueous electrolyte solution, e.g. HNO 3 or NaNO 3 solution comprising hydrazine, in an electrolytic cell 1 separated by a porous membrane 4 into cathode and anode zones, the dispersion being in the cathode zone 3 if the valency is to be reduced and in the anode zone 2 is the valency is to be increased. The immiscible aqueous solution may be a preferential solvent for (one of) the metal(s) in a lower or higher valency state. The one or more metals of changed valency state such as PuSP3+/SP from PuSP4/SPSP+/SP or NpSP5/SPSP+/SP from NpSP4+/SP may be separated by transfer to the aqueous solution. The dispersion may be formed by agitation with a stirrer 12. The membrane 4 may be of alumina or permeable cationic or anionic exchange resin in a polyethylene or vinyl resin. e.g. a solution of uranyl (USP6+/SP) nitrate and tetravalent Pu nitrate in tributyl phosphate and kerosene (or dodecane or gasoline) may be charged to the cathode zone containing an aqueous solution of HNO 3 and hydrazine for separating Pu, or a solution of PuSP4+/SP and NpSP4+/SP in the same solvent may be charged to the anode zone containing HNO 3 solution for separating Np. Organic solutions containing U and/or Pu and trace impurities, e.g. of Ru, Zr, and/or Nb, may be purified by forming a dispersion with HNO 3 solution in the anode zone. Other solvents for the organic solution include ketones e.g. hexone, or amines e.g. dioctylamine. The electrodes 5, 6 may be of Pt, Ta, Nb or C. The cell may be cooled and/or heated externally and internally. The aqueous solution separated from the dispersion drawn off may be recycled to the cell to increase the concentration of metal in the aqueous phase as described in Specification No. 1301375. For reducing the valency of Pu in the dispersion in the cathode zone, hexavalent U may be added as a redox agent.