ELECTROLYTIC REFINING OF BERYLLIUM (in Russian)
An electrolytic process of refining beryllium that would roduce material sufficiently pure for nuclear engineering applications was investigated. Nickel strip cathodes and commercial grade beryllium anodes were used. To avoid contamination by chlorine, an electrolyte of KF - NaF 2 BeF2 was first tried. The current efficiency attained was low; the metal was deposited in a finely- crystalline form and difficulties were experienced in washing off the solidified electrolyte. Since KCl- NaCl- 2 BeF/sub 2/ proved unsatisfactory for the same reasons, an electrolyte consisting of approximately equal proportions of beryllium and sodium chlorides was employed in subsequent experiments. The results of tests in which the cathode current density was varied between 4 and 16 amp/dm/sup 2/ showed that up to 12 amp/dm/sup 2/ the current efficiency remains practically constant, and a compact beryllium deposit consisting of bright crystals is produced. When the current density was increased to 16 amp/dm/sup 2/ , a small quantity of spongy deposit was formed. The beryllium anodes contained 4 to 5 x 10/sup -2%/ Fe, 1 to 5 x 10/sup -2/% Al, 2 x 10/sup -2%/ Cu, 1 x 10/sup - 3%/ M n, and 5 x 10/sup -2/% Ni. Variation of the anode current density between 6 and 50 amp/dm/sup 2/ hardly affected the impurity content of the cathode deposit, which contained 1 to 3 x 10/sup -3%/ Fe, 3 x 10/sup -3%/ Al and Ni, 1.5 x 10/sup -3%/ Cu, and 10/sup -3%/ M n. Determination of the current efficiency was the object of the next series of experiments carried out at 3 to 4 amp, cathode current density 8.8 to 12 amp/dm/sup 2/, temperature 340 deg C, and voltage 0.3 to 0.5 v. It was found that the time required for the current efficiency to attain a steady value was the same (about 24 hr), irrespective of the purity of BeCl/sub 2/ in the electrolyte, but the maximum current efficiency attained was lower when impure BeCl/sub 2/ was used. The current efficiency and recovery attained in a 180 hour test were 85 and 83% respectively. Under these conditions, 50% of beryllium was deposited in the form of large, plate-like crystals and 50% in the form of smaller grains, strongly adnering to the cathode. In view of promising results obtained, a series of tests on an industrial scale was carried out. A standard bath for electrolytic extraction of beryllium was used. The anode consisted of seven beryllium powder compact rings (each weighing 1 kg), suspended on a graphite rod. The voltage and current employed were 5.5 v and 800 amp. The electrolyte (50: 50 BeCl/sub 2/: NaCl) was replenished from an adjacent bath with an insoluble anode. The energy consumed in one test amounted to 34,000 amp-hr, the maximum output being 3.5 kg of refined beryllium, which corresponded to in average current efficiency of 80%. Recovery of beryllium attained was also 80%. The cathode deposit constituted 94% of the dissolved anode material. A homogeneous deposit, in the form of bright plate-like crystals, measuring 15 x 20 mm, Ads produced. For the preparation of anodes, beryllium obtained either electrolytically or by thermal reduction of fluoride, was used. In the former case, it contained case the impurity content was 0.12% Fe, approximately 0.01% Ni, and 0.01% Cu and Mn. In most cases the refined metal contained 0.005 - 0.006% Fe, 0.01% Ni, and 0.003% Cu; the manganese content did not exceed n x 10/sup -4%/, that of zinc and silicon being less than n x 10/sup - 3%/; the deposit contained less than 0.3 g/t boron and less than 0.04 g/t rare earths. The metal in the anodic slime collectcr contained (after washing) 0.05- 0.02% Fe, 0.05-0.03% Ni, and 0.02-0.03% Cu; no agglomeration of impurities in the electrolyte was observed. It was concluded that beryllium obtained by the process described satisfies most stringent requirements and approaches in quality metal refined by distillation. (OTS)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-15-026490
- OSTI ID:
- 4004255
- Journal Information:
- Tsvetnye Metally, Vol. Vol: 33: No. 12; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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