The Cherts Vanadium Ore Pollution-free Extraction Of Vanadium Pentoxide In New Technology Research,

Vanadium pentoxide is applied widely and has bright market prospect. With the price of vanadium pentoxide getting higher and higher, projects of vanadium extraction were carried out in all parts of nation. But in these processes, the recovery of vanadium is low and the environment is badly polluted and resources are wasted. The experiments were made by siliceous navajoite of a company in Henan. In these experiments, the extracting technology of acid-leaching and oxidizing roasting-acid leaching and vanadium extractation from system P204 and system TOA are used. And precipitation of vanadium are studied. A new non-pollution roasting and high recovery rate technology of extracting vanadium was researched.The results of oxidizing roasting-acid leaching showed: if siliceous navajoite was not roasted, the leaching rate of vanadium was low(≤25%), but if it was roasted, the leaching rate were greatly improved. When percentage of lime mud is 6%, roasting temperature is 850℃and time is 3h, then under the condition of mass concentration of H₂SO₄ 10%, the solid-liquid ratio 2:1, the temperature 70～80℃and agitation time 2～3h, the leaching rate of vanadium will reach up to 75%. Compared with traditional roasting process using sodium chloride, using lime mud as roasting additives not only solve the problem of air pollution, but also synthesize to make use of resources. And this method has an advantage of lower cost and less pollution.The extracting results showed: Compared with system P204, system TOA had better effect on extractation of vanadium in oxidizing roasting-acid leaching solution. And the technology can be simplified. When using system TOA to extracte, the pH of the leaching clear solution should be adjusted to 2.7～2.8 by ammonia water. Then under the condition of extractant of 2.5%TOA+1.5%TBP+96%Kerosene, O/A=1:4, contact time 2min and staying time 5min, one stage extractation rate can reach 95%. When it was anti-extracted twice under the condition of 0.5～0.7mol/LNa₂CO₃ and O/A=2:1, the anti-extratation rate can be up to 98%. Anti-extractation solution can be directly used to precipitate vanadium.The precipitation of vanadium results showed: ammonium ployvanadate can be directly precipitated through adding ammonium chloride. In the 18～21g/L of acid vanadium solution, the optimum technological condition of precipitating vanadium were determined to be: pH=5, the coefficient of ammonification K=2.5, temperature 90℃and time 120min. The precipitation rate of vanadium was over 97% and the retrieving rate was higher than 70%. After roasted, the purity rate of products was 98% and they were achieved national standard(GB3283-87).