Extraction of vanadium from black shale using pressure acid leaching
The extraction of
vanadium from
black shale was attempted using pressure acid
leaching. The effects of the several parameters which included reaction time, concentration of
sulfuric acid, leaching temperature, liquid to solid ratio and concentration of additive (FeSO
4) upon leaching efficiency of vanadium were investigated and a two-step
counter-current leaching approach was developed.
The results showed that the leaching efficiency of vanadium in the two-step process could reach above 90%. Vanadium was effectively separated and enriched by
solvent extraction after
leachate pretreatments, including the reduction of Fe
3+ and adjustment of pH value.
The extraction and stripping yields of vanadium were both > 98%.
Ammonia was added to a stripping liquor to precipitate vanadium and then the
ammonium poly-vanadate produced was calcined at 550 °C for 3 h to produce the high purity V
2O
5 powder. The overall yield of vanadium through all process stages was about 85%.
(20min delay)