Study On Technique To Prepare Vanadium Pentoxide Via Dynamic Continuous Purification

Vanadium shale is the dominant characteristic vanadium resource in China,and vanadium precipitation in vanadium shale extraction process is a necessary step for the preparation of terminal vanadium oxide products.In the actual industrial production,the mainstream ammonium salt vanadium precipitation will produce a large number of ammonia nitrogen wastewater,and the purity of other conventional vanadium precipitation process products is not up to standard,which is extremely unfavorable to the sustainable development of vanadium industry.In this study,by integrating the advantages of the existing vanadium precipitation process,the hydrolysis vanadium precipitation process was used to obtain the hydrolysis vanadium precipitation product,and then the ammonium salt solution was used for purification.A combination process with environmental friendliness and high purity of vanadium dioxide products was developed,namely,the hydrolysis vanadium precipitation-ammonium salt purification process.It not only greatly reduces the use of ammonium salt,but also can prepare high purity vanadium dioxide products.In this paper,the optimum conditions of hydrolysis and precipitation of vanadium were studied.The product of hydrolysis and precipitation of vanadium was Na V₃O₈·1.5H₂O.Using ammonium chloride as purification agent,the optimum static purification parameters were determined as follows:ammonium addition coefficient 2,purification time 5min,temperature 65°C,purification times twice.The static purification product was（NH₄）₂V₆O₁₆·1.5H₂O.After calcination,99-grade vanadium pentoxide meeting the black metallurgical industry standard was prepared.Compared with ammonia and ammonium salt precipitation process,the ammonium consumption of the combined process was reduced by 80%,and the product purity was increased by 0.70%and 1.01%,respectively.Through detection and analysis,it was preliminarily determined that NH₄⁺in the solution replaced Na⁺in Na V₃O₈·1.5H₂O crystal in the purification process,thereby improving the purity of vanadium pentoxide products.The optimum single-stage dynamic purification process conditions were determined as follows:ammonium addition coefficient 2,flow rate=1 ml/min,temperature 65°C,calcined to prepare grade 99 vanadium pentoxide.The process was continuous and productive.At the same time,through the continuous dynamic purification process,the concentration of ammonium ions in the purified residual solution was reduced from 9758mg/L to 55.93 mg/L after setting a 7-stage purification tank,and the utilization rate of ammonium chloride reached 99.43%,which reduced the production of ammonia nitrogen wastewater.At the same time,according to the properties of the solution,the enrichment trend of various ions in the solution is explained.