Crystallization Separation of Na3VO4 and Na2CrO4 in
Multi-component System of Sub-molten Salt Method for Processing
Vanadium slag
Shaona Wang1, Hao Du1, Shili Zheng1, Man Feng1, 2, Yi Zhang1
(1. National Engineering Laboratory Hydrometallurgical Cleaner Production Technology,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China；
2. University of Chinese Academy of Sciences, Beijing 100190, China)
Abstract:
The
solubility
data
of
Na3VO4
and
Na2CrO4
in
the
NaOH−Na3VO4−Na2CrO4−H2O quaternary system at (40 and 80)℃ were measured.
Based on the data and the digestion liquor obtained by the sub-molten salt oxidation
decomposition reaction, separating Na3VO4 by cooling crystallization first followed
by evaporative crystallization of Na2CrO4 is preferred. The effect of crystallization
process parameters was also studied. The results showed that Na3VO4 was optimal
separated when the NaOH concentration was 300 g/L, stirring speed 160 r/min,
temperature from 80 ℃ to 40 ℃ with cooling rate 1 ℃/min, seed load 1 %(),
holding time 90 minutes. Under the optimal conditions, the crystallization rate of
Na3VO4 was more than 54 %, and the purity of the crystal was above 93 %. Then
Na2CrO4 was separated when the NaOH concentration evaporated to 650700 g/L,
and the purity was above 90 %.
Key Words: Sub-molten Salt, Vanadium slag, Na3VO4, Na2CrO4, Crystallization