A new process for the separation of niobium pentachloride from iron chloride was studied from the standpoint of the recovery of niobium from its iron-containing ore and from scraps. In this process, the niobium pentachloride is transported from the iron chloride in the presence of sodium chloride forming sodium hexachloroniobate. The separation experiments were conducted using double cells with two compartments. In the case of the NbCl3-FeCl3 system, FeCl3 tended to remain in the compartment in which the mixed chloride was placed, while NbCl5 was transported to another compartment forming NaNbCl6 stable complex. The transport efficiency and and chloride purity obtained were investigated under several conditions. The best separation was achieved when the molar ratio of NaCl to mixed chloride and reaction time were 6 and 3 days, respectively. The transport efficiency of NbCl5 increased with increasing temperature and became stable over 300 °C. The chloride purity obtained decreased, corresponding to the increasing transport efficiency of FeCl3 over 200C. A very high separation effect was observed when sodium chloride was used compared to the separation result without sodium chloride. Selective reduction of FeCl3 in the NbCl5-FeCl3 mixture by iron and ferroniobium metal was shown to be effective resulting in the recovery of very pure NbCl5 (Fe:2 ppm) with 99.9% transport efficiency. Aluminium in the NbCl5-FeCl3 mixture obtained from the chlorination of ferroniobium showed similar transport behavior to that of the AlCl3-FeCl3 mixture.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Physical and Theoretical Chemistry