Leaching of vanadium from carbonaceous shale

The leaching of vanadium from carbonaceous shale using dilute H2SO4 was investigated, and the mechanism of leaching determined. The results showed that higher leaching efficiency of vanadium was obtained by increasing initial concentration of H2SO4, raising leaching temperature and prolonging leaching time. Addition of ammonium fluoride also enhanced recovery. A recovery of 92% was obtained using a liquid to solid ratio 4:1, initial H2SO4 concentration 18%, NH4F addition 4.8 wt.% of carbonaceous shale, leaching temperature 95 °C and contact time 8 h; the recovery was only 56% without NH4F. The presence of NH4F enhanced the leaching of vanadiferous mica.