Study On Leaching Of Vanadium Of Typical Vanadium-Containing Minerals Strengthened By Additives

As an important strategic resource,vanadium is widely used in iron and steel metallurgy,titanium alloy,chemical industry and energy storage.The process of mineral processing pretreatment and mechanical activation before leaching in the process of vanadium extraction from vanadium-containing minerals will cause the increase of fine particles and the increase of slurry viscosity,which is not conducive to the leaching of vanadium.In order to expand the source of vanadium extraction minerals,there is also a problem of low leaching rate of low valence vanadium in vanadium extraction by reducing smelting slag.In this paper,two kinds of typical vanadium-bearing minerals,the vanadium-rich titanium slag obtained by reduction roasting and grinding of sea sand ore and the fine-grained vanadium shale,were selected as the research objects.The experimental study on vanadium leaching enhanced by oxidant and dispersant was carried out,and the principle was analyzed.The main conclusions are as follows:(1)The vanadium-rich titanium slag was leached by H2SO4,when the volume fraction of H2SO4 is 25%,leaching temperature is 95℃,the addition amount of Ca F2 is 5wt.%,leaching time is 5h,and liquid-solid ratio is 5:1m L/g,the stirring speed is 400r/min,the leaching rate of vanadium is 73.40%.The study of vanadium leaching from vanadium-rich titanium slag strengthened by oxidant showed that when the addition of Na NO3 is 1wt.%,the leaching rate of vanadium is 89.91%,increased by 16.51%.When the addition of Mn O2 is 3wt.%,the leaching rate of vanadium was 83.76%,increased by 10.36%.The proportion of trivalent vanadium in vanadium-rich titanium slag is 72.73 %.In this acid leaching system,the potentials of Mn O2/Mn2+,NO3-/NO2-and NO3-/HNO2-are larger than those of VO2+/V3+ and VO2+/VO2+,Gibbs free energy ΔG of vanadium leaching system decreases and the reaction equilibrium constant lg K increases after adding oxidant,the addition of oxidant can oxidize insoluble low-valence vanadium into easily leaching high-valence vanadium.(2)For fine-grained vanadium-bearing shale,the leaching rate of vanadium is only 62.0 % when the volume fraction of H2SO4 is 8 % and the liquid-solid volume-to-mass ratio is 1.5:1 m L/g.The study on vanadium leaching enhanced by dispersant shows that the order of enhancing effect is: sodium tripolyphosphate > sodium hexametaphosphate > sodium humate > sodium silicate.When the addition amount of sodium tripolyphosphate is 1.0wt.%,the leaching rate of vanadium increases from 62.0% to 72.1%.After the adsorption of particles by anionic sodium tripolyphosphate,the electrostatic repulsion between particles is increased,the viscous force is weakened,and the slurry viscosity is reduced.Dispersants mainly change the leaching rate of vanadium by adsorbing on the mineral surface and changing the viscosity of slurry,and the dispersant has a weak dispersing effect on finegrained particles.