Study On Vanadium Extraction From Stone Coal By Blank Roasting Process And Thermodynamics Of Sulphric Acid Leaching With Leaching Agent

China has large and widespread reserves of stone coal, which is a type of V-containingresource peculiar to China. In the process of extracting vanadium out of stone coal, it is neededto break the crystal structure of V-containing minerals to let out the vanadium inside, in this wayvanadium gets to be extracted. An important idea to increase the gross recovery of vanadiumduring this process is to intensify the leaching conditions by adding leaching agent, thus breakingthe crystal structure of V-containing minerals effectively and obtaining a better leachingefficiency.The process of blank roasting-sulphuric acid leaching of vanadium with leaching agent wasstudied in this paper by using stone coal in Hubei province as raw material，also was the effectthat leaching agent had on the process and the mechnism of structural damage that F-containingleaching agent did to F-containing mica from the perspective of thermodynamics.The optimal parameters of the process of blank roasting-sulphuric acid leaching ofvanadium with leaching agent from stone coal are studied. The result shows that the leaching rateof vanadium can exceed86%under the conditions that roasting temperature remains at700℃for1h, roasted residues with the particle size smaller than0.074mm account for70%,liquid-solid ratio is1.5:1, sulfuric acid concentration is4mol/L, stirring rate is300r/min,leaching period is4h, the dosage of F-containing leaching agent is5%of the raw ore’s mass,and leaching temperature remains at98℃.We can come to a conclusion that blank roasting can change the internal structure of mica,thus causing the valence change of vanadium, and the damage it does to the structure of mica inthe blank roasting process is much less than that with the addition of F-containing leaching agent.Instead, with the addition of F-containing leaching agent, the damage to V-containing mineralwhich require to be done by roasting is transferred to the leaching process partially, thuslowering the standards of roasting process.The addition of F-containing leaching agent cannot contribute to the destruction ofV-containing mica and the increase of leaching efficiency of vanadium by intensifying the directreaction between sulfuric acid and vanadium in the crystal structure of roasted residue; Instead, itcan destruct the structure of muscovite by promoting the bond fission of Al-O in the muscovitecrystal structure, thus increasing the leaching rate of vanadium. With the addition of F-containingleaching agent, the Al and Si in the muscovite crystal structure tend to react with F and form thecomplex, making the Δ GθTof dissolution reaction of muscovite significantly lower than that ofwithout the addition of F-containing leaching agent and making the logKTθsignificantly higher,which means the dissolution reaction is easier to happen in this situation, also the forwardreaction is more adequate.