According to the content ratio of niobium and tantalum in the original guess, two methods of separation extraction or separation extraction were selected. When the content of niobium and tantalum differ greatly, the separation extraction method is mostly used. FIG. 1 shows the curves of niobium and tantalum extracted by MIBK. As can be seen from the figure, when separation extraction was selected, niobium was extracted first under low acidity, and tantalum was extracted under high acidity. Co-extraction is to extract niobium tantalum into organic phase together, and then reverse extraction of niobium and tantalum from the loaded organic phase of niobium tantalum, that is, reverse extraction of niobium with high acidity and reverse extraction of tantalum with low acidity. The equipment of extraction method is simple and easy to operate, which is widely used in niobium and tantalum factories in the world. After the extraction of niobium tantalum into organic phase, the separation of niobium tantalum with the washing load and the reverse extraction becomes the key link. According to the selected extraction agent and water phase material liquid and choose the appropriate detergent and reverse extraction agent. For example, the extraction system of sec-octanol -HF-H2SO4 is generally used to wash the loaded organic phase with sulfuric acid solution, with 41mol/L of h2so2.
Solution reverse extraction niobium, pure water reverse extraction tantalum. By adding the volume ratio of organic phase and aqueous phase, the extraction rate of niobium tantalum can be improved. Other metal ions extracted in the form of fluorine complexes in aqueous phase solution include Sn2+, Sn4+, RE3+, etc., and those that can be partially extracted include As3+, As5+, Mo5+, Se4+, Fe3+, W6+, V3+, V5+, Sb5+, etc. The acidity of the aqueous solution was optimized by the full concentration of niobium and tantalum in the organic phase. Impurities entering the organic phase are washed off with a sulfuric acid solution or a mixture of sulfuric acid and ammonium sulfate. For niobium and tantalum full of sec-octanol with H2SO44mol/L solution with the best washing effect. The extraction equipment selected for niobium and tantalum separation in the industry is multi-stage box-type mixing clarifier or extraction tower (packed tower, sieve plate tower, etc.). Because HF - H2SO4 mixed acid is highly corrosive, it is widely used in multi-stage box mixing clarifiers made of low pressure polyethylene sheets, welded polysheets or lined with polytetrafluoroethylene. After hf-h2so4 leaching, the residue of niobium tantalum concentrate extracted by pulp is less, and the residue is not filtered. Niobium - tantalum slurry extraction method is widely used in China. Compared with clear liquid extraction, pulp extraction can save the filtration and washing of the residue of differentiation, shorten the production cycle, reduce the labor intensity, improve the working conditions, and facilitate the process of sealing and continuous.
