Experimental Study On Preparation Of High-purity Vanadium Pentoxide By Ammonium Polyvanadate

Vanadium and its compounds are widely used in metallurgy, chemical industry, medical treatment, energy and other fields. Vanadium pentoxide is one of the most important vanadium compounds, and it is the basic material for the preparation of vanadium-base alloys, vanadium alloys, vanadium batteries and catalysts.The product of vanadium extraction gives priority to industrial vanadium pentoxide which concentration is 98% in our country.With the expansion of the application field in vanadium,the requirement of the high purity vanadium(above 99%) for new materials and vanadium battery is increasing.Based on the study of literature and with the principle of efficient and economy,the paper has the experimental study of preparing high-purity vanadium pentoxide with deep purification aimed at the production polymer ammonium vanadate(95.41%) produced by extracting vanadium from stone coal in Shaanxi Shangluo.The process route and process conditions were determined,the research results have important application value for improving the economic value of vanadium industry in Shaannan.The main contents are as follows:(1)Regard the ammonium polyvanadate prepared by stone coal acid leaching as the raw material,through the technical route as this: remove iron directly by alkali dissolutionâ†'remove silicon and phosphorus by purification â†'vanadium precipitated in alkaline solutionâ†'calcinationâ†'high-purity vanadium pentoxide.Compared with using industrial vanadium pentoxide prepare high-purity vanadium pentoxide, the technical has shorter process and higher economic benefit.(2)Ammonium polyvanadate take the method that use sodium hydroxide solution to remove iron. The results showed that dissolved 50 g polymer ammonium vanadate which Solid-liquid ratio is 1:4 into sodium hydroxide solution which mass fraction is 7.5%,under the condition of 90℃,stirring reaction for 2 hours to made iron ion precipitated, it can remove iron ion effectively, the iron removal ratio can reach 92%.After Solid-liquid separated, the filtrate remove impurity and purification further.(3)The rich vanadium liquid after iron removed and purification remove silicon and phosphorus by add Magnesium chloride. An experiment was done about the factors the amount of magnesium chloride, reaction temperature, reaction time, pH, reaction temperature and static time influence on removal rate of impurity and loss rate of vanadium. The results show that: Add 10 mL MgCl2 which mass fraction is 20%,control solution for weak alkaline, with the condition of initial pH is 9.5,reaction temperature is 60℃ and reaction time is 30 min,it could effectively remove silicon and phosphorus impurities in the solution, the removal rate can reach above 96%.(4)The crystallization of partial ammonium vanadate and preparation of high-purity vanadium pentoxide. The paper investigated the influence such as the reaction time, amount of ammonium salt, reaction temperature, the initial pH of solution, static time and other factors when partial ammonium vanadate generated on the ratio of vanadium precipitated in the process of partial ammonium vanadate crystals generated. The best process conditions for vanadium precipitated is: the reaction time is 1h,add ammonium coefficient K=1.4, reaction temperature is 90℃, initial pH is between 8.8 and 9.2,stirring speed is 300r/min, the ratio of vanadium precipitated can reach above 99%.Calcine the partial ammonium vanadate generated by vanadium precipitated 2h in the Muffle furnace under the temperature of 550℃ could generate vanadium pentoxide which is epigranular and The purity can reach 99.64%.(5)The preparation process of high-purity vanadium pentoxide is determined on the basis of experiment, the process is green and easy to make industrial production.