| Vanadium pentoxide with high-purity is the basic raw material for the preparation of vanadium and vanadium compounds,which has excellent physical and chemical properties and has become a research hotspot in the research field.The process of preparing vanadium pentoxide with high-purity produce waste water,waste gas and waste residue pollutes the environment.Therefore,based on the preparation of 99.9%vanadium pentoxide from vanadium slag,removal of silicon slag,removal of chromium slag,crystallization of ammonium metavanadate and the upper liquid lotion in the recovery and utilization of valuable elements.The main research contents and results are following:(1)Leaching of silica residue by H2SO4 and deep filtration,with the recovery of high purity ammonium vanadate crystals in the upper liquid ammonia for preparation of ammonium sulfate solution(300?400g/l,PH=1.5?2.8).The crystallization of ammonium aluminum sulfate,NH4+:Al3+(molar ratio)=1.2:1,the temperature of 40,PH=2.6?2.8.A small amount of residual in crystal liquor Al3+ and V5+:1?4g/l,will return to the crystallization solution of leaching solution containing vanadium,and aluminum sulfate to remove silicon,adding aluminum silicon molar ratio of 0.8:1,can make the silicon content reduced to below 50mg/L,then adjust the PH=8.0-8.5 to remove Al3+,can be in the solution of Si and Al3+ impurity content is reduced to below 20mg/L.(2)The use of sodium pyrosulfite reduced chromium raffinate,sodium metabisulfite is added to the theoretical quality of 1.15?1.2 times,adding sodium carbonate and produce chromium slag and wastewater,wastewater Cr6+<0.5 mg/L,COD<300mg/L,chromium slag after washing the sodium ion content can be reduced from 6.5%to 2.4%.The chrome slag and chromium hydroxide mixed by 1:1,put in the muffle furnace at 1300-1350? for calcination of chromium oxide,the reaction heat of unit charge is 2.98×103KJ,with a coefficient of 0.97 aluminum chromium metal smelting(Cr?98.5%),meet the requirements of JCr-99A impurity.(3)Through the comparison of various resins,the D296 resin which has wide application range of pH value and strong solution temperature is selected as the adsorption material.The adsorption of D296 resin obeys the Freundlioh isotherm adsorption curve,n=4.6 the adsorption of resin for vanadium is easy to carry out,and PH=3.5 the adsorption vanadium of resin is 278mg/g.Adsorption of vanadium by D296 resin as endothermic reaction ?H=7.44KJ/mol,and the adsorption reaction was in accord with Boyd liquid film formula.When the initial pH value was 10.5,the room temperature and the resin/liquid ratio was lg/100mL,the adsorption effect was the best.Loaded resin Using 3mol/LNaOH analysis,vanadium removal rate was above 95%,and the resin reuse performance is stable.(4)Ammonia and vanadium rich organic phase mixed by 1:4,stripping and crystallization of ammonium metavanadate together,stirring speed 200r/min,the temperature of 40,adding ammonium metavanadate for 0.8%of the total as a seed,reaction for 2.5 hours,the ammonium metavanadate maximum diameter of 59.15?m. |
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