Preparation of High-Purity Cobalt by Anion-Exchange Separation and Plasma Arc Melting

Abstract

MASAHITO UCHIKOSHI, HIDEKA SHIBUYA, JUNICHI IMAIZUMI, TAMÁ S KÉ KESI, KOUJI MIMURA, and MINORU ISSHIKI High-purity Co was prepared with valence-controlled anion-exchange separation, oxidation refining using plasma arc melting, and H 2 -Ar plasma arc melting on a pilot scale. The result of a laboratory-scale experiment indicated that the slower flow rate is more effective to remove the impurities by anion-exchange separation. However, the separation efficiency is reduced by scaling up the column from the laboratory to pilot scale. The discussion of the decrease in the separation efficiency implies that the distribution coefficient increases as the concentration of the adsorbate is lowered, but a reduced slower flow rate might increase the final purity of Co. In addition to anion-exchange separation, Co oxidation refining using plasma arc melting was useful. Consequently, a high-purity Co of 99.9998 pct by mass excluding gaseous elements was prepared, which represents the highest purity reported.

Modeling of Elution Curves in Preparative Chromatography Using Anion-Exchange Resin for Cobalt Purification

“…This type of shoulder has been observed frequently in anion-exchange separations of various metals. [2][3][4][5][6][7][8][9][10][11] Fitting with the plate theory in multi-path mode reveals that the peak of path #2 is responsible for the shoulder demonstrated in Fig. 6.…”

“…[1][2][3][4][5][6][7][8][9][10][11] The anionexchange separation procedure consists of an initial charging-rinsing stage, in which the objective element is fixed in the resin phase and then eluted by changing the composition of the rinsing solution, which lowers the distribution coefficient. The ions, which have significantly higher distribution coefficients than that of the objective element, are retained in the resin bed during the elution stage.…”

Effect of Static Magnetic Field on Recalescence and Surface Velocity Field in Electromagnetically Levitated Molten CuCo Droplet in Undercooled State

“…To prepare spherical samples of CuCo with a mass of approximately 0.6 g (5 mm diameter), copper with a nominal purity of 99.9999999 mass pct (JX Nippon Mining & Metals) and cobalt with a purity of 99.9998 mass pct [15,16] were first weighed out in the correct proportions and melted together using an arc melting furnace. Then, the solidified samples were levitated and remelted by the electromagnetic levitator in Figure 1 so that the compositions in the samples could be homogenized by utilizing MHD convective mixing, similarly to in our previous work.…”