Preparation Of High Purity Vanadium Pentoxide And Determination Of P, Si And Al

In recent years, vanadium pentoxide has been widely used in some high-tech fieldssuch as aerospace, aviation, vanadium battery materials, because of its excellentphysical and chemical properties and thermal stability, but these areas have higherquality requirements to vanadium product. At present the purity of the vanadiumproduct be sold mainly is98%on the market, which is much lower than materialsstandard to be mentioned in the above. In order to meet the development needs of thematerials industry, it is necessary to study how to remove the impurities in vanadiumproduct, and vanadium of purity which is98%has become saturated on the market.Therefore, in the paper, it was presented that the depth removes of aluminum throughthe complete removals of phosphorous and silicon by calcium and aluminum mixedprecipitation to the impurity removal of vanadium solution by acid precipitation methodand ion exchange method, and then precipitated vanadium product was preparated highpurity vanadium pentoxide by calcination, its main study content are as follows:Determining method which ammonium metavanadate was dissolved throughpreliminary experiments, that is, the mass of ammonium metavanadate which wasadded to water was based on the mass ratio of ammonium metavanadate: water=1:10,and then slowly adding sodium hydroxide which the mass were0.5times of ammoniummetavanadate, and until the ammonium metavanadate completely was dissolved, bedissolved ammonium metavanadate, which then was heated to90°C, until isnot productammonia.By analysis of the silicon and phosphorus removal method, it was determined thatthe one step removal at the same time silicon and phosphorus in the vanadium solutionby calcium-aluminum mixed preparation, and the effects of addition amounts of calciumsalt and aluminum salt, pH, temperature and time on the removal of P and Si wereinvestigated. The results showed that the removal of silicon and phosphorus werereached in more than98%and vanadium loss solution within7%under the optimumprocess condition that pH9-10, calcium chloride of0.045times of the mass ammoniummetavanadate, aluminum chloride of0.055times of the mass ammonium metavanadate,60°C and time40minutes. So the used method can be better to remove silicon andphosphorus in the vanadium solution.It should be remove that calcium and aluminum in vanadium solution because oftheirs were introduced in the process of silicon and phosphorus removal and accordingto removal principle. Although calcium was added in the process of removing siliconand phosphorus, but it was found in experiment that the absence of calcium ions in thesolution after removal impurities because aluminum and calcium can coprecipitation.Therefore, only aluminum is considered for removal of impurity in the solution afterremoval Si and P. For the removal of the aluminum，ion exchange was used to removal of aluminum after the part of aluminum was sedimentated by adjusted pH.20minutesof reaction time,60minutes of standing time; the aluminum concentration can bereduced to below5mg/L in the solution under this condition. By the adsorption factorsof D402resin to aluminum adsorption were investigated such as acidity, time,temperature, flow rate. Concluded and preliminary process as follows: the adsorptionquantity of D402is2.372mg/g to aluminum, pH6-6.5, flow rate to2BV/h, andaluminum concentration in the solution is less than1mg/L after purification.The effect of vanadium precipitation by ammonium salt is better than by hydrolysis,the rate of vanadium precipitation and the content of vanadium product were higher,Especially vanadium precipitation by weakly alkaline ammonium salt, therefore thismethod was chose as vanadium of precipitation in experiment from the technologyprocess, technology of vanadium of precipitation condition as follow:80℃oftemperature,7.5-8of pH,1.5of add ammonia coefficient,20minutes of reaction time,60minutes of standing time. In the above condition, the rate of vanadium precipitationis more than99%.Technology process was simulated by using technical grade ammoniummetavanadate according to technology flow and the technology parameters. Theexperimental results show from5times of balance experimental that process parametersof experiment is relatively stable and deviation of experiment result is smaller.Preparated high-purity vanadium pentoxide reached99.9%. By the preliminary materialcost budget and the prices of ammonium metavanadate is75000yuan. The direct cost is118000yuan to produce one ton of high purity vanadium pentoxide. So have good profitspace.In addition, there is no better way to determine P, Si and Al in the vanadiumproducts at present because of the interference of vanadium-based. Therefore, theoptimum conditions of determination and elimination of vanadium-based interferencewere studied this paper, which molybdenum blue method measure the silicon,phosphorus and phenyl fluorone method determine aluminum. The results showed that:Interference of vanadium-based may be eliminated by the calculation and relativedeviations were respectively within±2%,±2.5%,±1.9%to determination of P, Si andAl.