Study On Improving The Production Process Conditions For Ultra-fine Niobium Oxide And Pollution Control

Tantalum niobium smelting belongs to the high pollution industry.It is particularly important to research and development resources sustainable utilization of green methods and techniques,to development the cleaner production and environmental friendly production process.For the tantalum niobium containing fluorine of ammonia nitrogen wastewater in the process of smelting,this paper put forward two kinds of feasibility processing methods:one is the use of the extraction process so that SO₄^2-and F^-separated and removed sulfate,ammonium hydrogen fluoride concentration and recovery directly.By adjusting the acid,acid ratio,phase ratio,contact time,the concentration of feed solution and other conditions to optimize the extraction of niobium get optimal conditions:H₂SO₄ to 3 mol·L^-1,the concentration of HF is 1.2 mol·L^-1,the extraction phase ratio of 1:3,the contact time:5 min,under conditions of castor oil as extraction solvent,the extraction rate of 93.04%.The organic phase was extracted as much as possible to reach saturation,the lower the stripping solution root sulfuric acid concentration.Stripping solution containing a small amount of sulfate can be removed the sulfate with barium hydroxide in ammonia liquor after precipitation.The mother liquor after treatment by evaporation,obtained a mixed product of ammonium fluoride and ammonium hydrogen fluoride.Another effective use of containing fluorine ammonia nitrogen wastewater method is:using solubility rare-earth salt to remove the fluorine in the mother liquor of niobium tantalum precipitation,its products could be made into rare earth polishing powder containing fluoride or rare earth fluoride,and the mother liquor after defluoridation could be recycled as leaching agent of ion type rare earth ore in South China.The results show that:fluorine in mother liquor was removed by adding rare earth sulfate,then ammonium bicarbonate was added to control the pH value of6.2⁶.4 for the precipitation of rare earths,and then the precursor of fluoride rare earth polishing powder was obtained.After precipitation,the fluorine content could reach 5.0 ppm,the rare earth content was 30 ppm;when adding rare earth chloride fluoride and controlling the pH value at 6.5⁶.7,the fluorine content in mother liquor could reach 3.0 ppm,rare earth content was 20 ppm;it was advisable to control the precipitating pH value at 7.0,when removing fluorine in mother liquor of niobium tantalum precipitation by adding soluble rare earth salt to get rare earth fluoride.After fluoride precipitation,the fluoride content in mother liquor could reach 2.5 ppm,rare earth content was 10 ppm.Removing fluorine from niobium tantalum precipitation mother liquor by adding soluble rare earth salt,ammonium bicarbonate precipitation of rare earth was completed;after rare earth salt precipitation filtration,drying at1000¹050?and calcining for 4 h,fluoride rare earth polishing powder with uniform particle size distribution,narrow particle size range,appropriate median size and high corrosion rate was got.After removing fluoride,precipitation mother liquor was recovered by evaporation to get ammonium sulfate or ammonium chloride and ammonium sulfate complex,the salt content of the resulting product was more than98%,and the fluorine content was less than 3 ppm.Existing of niobium oxide process improvement,reducing the dosage of precipitant and the pollution in the process of production,prepare ultra-fine niobium oxide.The effects of concentration,precipitation temperature,calcination temperature and calcination time on the particle size and morphology of niobium oxide were investigated.The powders were characterized by TG-DTA,SEM,particle size analyzer,and the results showed that the:adopting niobium material liquid concentration of Nb₂O₅ 60-100 g·L^-1,small blade medium-speed stirring,precipitation temperature at 75±5?,liquid ammonia precipitation reaction?ventilation from export level 0.5-1.5 cm?,calcination at 700?for 2 h,obtained good dispersion,D50 is about 350nm long cylindrical niobium oxide ultrafine products.Extracted twice with distilled water and then calcined 2 h at 700?,fluorine in niobium oxide reduced more than 95%under the same conditions,and the reaction is sealing system with the conventional reaction compared,reducing the amount of ammonia,achieving the effect of energy saving and emission reduction.The method can be used for industrial production of ultrafine niobium oxide.