Electrorefining of vanadium prepared by carbothermic reduction of V 2 O 5
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Electrorefining of Vanadium Prepared by Carbothermic Reduction of V205 K. P. V. LEI AND T . A .
SULLIVAN
Scale, inches
IN a
c o o p e r a t i v e r e s e a r c h p r o g r a m on vanadium with the A t o m i c E n e r g y C o m m i s s i o n , the B u r e a u of Mines has s u c c e e d e d in p r e p a r i n g h i g h - p u r i t y vanadium by m o l t e n salt e l e c t r o r e f i n i n g a c r u d e vanadium feed m a t e r i a l p r e p a r e d by c a r b o t h e r m i c r e d u c t i o n of vanadium pentoxide. T y p i c a l e l e c t r o r e f i n i n g t e s t s w e r e m a d e with an initial cathode c u r r e n t density of 220 a m p p e r sq ft in a KCI-LiC1-VCle e l e c t r o l y t e at 620~ In one r e f i n i n g step 73 pct of the vanadium was r e c o v e r e d at a c u r r e n t e f f i c i e n c y of 97 pct. The product was 99.9 pct V, containing l e s s than 200 ppm of i n t e r s t i t i a l i m p u r i t i e s , and had an a v e r a g e h a r d n e s s of 70 Dph. The c a r b o t h e r m i c - r e d u c e d vanadium, Fig. 1, was p r e p a r e d at the A m e s L a b o r a t o r y , Iowa State U n i v e r sity. The technique f o r p r e p a r a t i o n of r e f r a c t o r y m e t a l s f r o m t h e i r o x i d e s has been d e s c r i b e d by W i l helm and McClusky. 1 The a n a l y s e s of the s t a r t i n g vanadium pentoxide and the r e d u c e d vanadium a r e given in T a b l e I. X - r a y d i f f r a c t i o n p a t t e r n s indicated the c a r b o t h e r m i c - r e d u c e d m a t e r i a l was vanadium and V2C. The v a n a d i n m - c a r b o n phase d i a g r a m has been r e p o r t e d by Rudy, et al.2 The m o l t e n salt e l e c t r o r e f i n i n g of v a r i o u s g r a d e s of K. P. V. LEI and T. A. SULLIVAN are Research Chemist and Research Supervisor, respectively, Boulder City Metallurgy Research Laboratory, U. S. Department of the Interior, Bureau of Mines, Boulder City, Nev. Manuscript submitted March 29, 1971. 2312-VOLUME
2, A U G U S T 1971
Fig. 1--Carbothermic-reduced
Table I. Armlysis of V20 s and Carbother
V20 s Aluminum Carbon, combined Carbon, free Chromium Iron Nickel Nitrogen Oxygen Silicon Vanadium
0.1 0.008 0.037 0.012 0.029 -
vanadium.
Vanadium, Pet
Carbothermic Vanadium 0.1 4.54 0.05 0.008 0.050 0.001 0.009 3.32 0.006 90.20
vanadium has been d e s c r i b e d Y 8 A 12-in. diam e l e c t r o l y t i c c e l l equipped with a m o l y b d e n u m c r u c i b l e that contained 60 lb. of m o l t e n KC1-LiCI-VC12 e l e c t r o l y t e was u s e d for the r e f i n i n g . The e l e c t r o l y t e was p r e p a r e d by d i r e c t c h l o r i n a t i o n of vanadium into the m o l t e n KC1-LiC1 eutectic m i x t u r e at 750~ The final c o m p o sition of the e l e c t r o l y t e w a s , in wt p c t , 50 KC1, 39 LiC1, and 11 VC12. A total of 8.30 kg of the vanadium feed 3 m a t e r i a l was c r u s h e d into a p p r o x i m a t e l y ~- -in. chunks and i n t r o d u c e d into the c e l l in a c o n c e n t r i c molybdenum MErAI. I UR(;It'AI. TRA
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