The industrial processes for recovery of niobium and tantalum oxides depend on hydrofluoric acid, which is a highly toxic and corrosive reagent with significant environmental consequences. This study presents a fluoride-free, rapid, and energy-efficient process for niobium and tantalum extraction from columbite using microwave-assisted alkali treatment and solvent extraction. Microwave treatment was optimized using an experimental design to obtain a statistical model for maximum dissolution. It was found that it is possible to obtain a temperature of more than 600 °C within 4 min of microwave treatment with potassium hydroxide. Water leaching of the microwave-treated sample resulted in dissolution of 93.57 pct niobium, 88.12 pct tantalum, 11.17 pct tin, and 21.09 pct iron. Solvent extraction with methyltrioctylammonium chloride was used to separate niobium and tantalum from aqueous solution. Approx. 96.2 pct niobium along with 93.4 pct tantalum was co-extracted at the organic-to-aqueous phase ratio of 2/1 in a two-stage counter-current extraction with 0.29 M extractant. Selective stripping of niobium from the loaded organic solution was performed with a mixture of 0.5 M nitric and oxalic acid, while tantalum stripping was achieved with high nitric acid concentration (1 M). Finally, > 98 pct pure niobium oxide and Ta-rich mixed oxide were prepared by the precipitation of the purified solution.

回收铌和钽氧化物的工业过程依赖于氢氟酸，氢氟酸是一种剧毒和腐蚀性试剂，会对环境造成重大影响。本研究提出了一种使用微波辅助碱处理和溶剂萃取从钶铌中提取铌和钽的无氟化物、快速且节能的工艺。使用实验设计优化微波处理以获得最大溶出度的统计模型。发现用氢氧化钾微波处理 4 分钟内可获得超过 600 °C 的温度。微波处理样品的水浸出导致 93.57% 的铌、88.12% 的钽、11.17% 的锡和 21.09% 的铁溶解。用甲基三辛基氯化铵溶剂萃取用于从水溶液中分离铌和钽。约 96.2 pct 的铌和 93.4 pct 的钽在两级逆流萃取中以 2/1 的有机相与水相的比例共萃取，萃取剂为 0.29 M。用 0.5 M 硝酸和草酸的混合物从负载的有机溶液中选择性地剥离铌，而用高浓度硝酸 (1 M) 实现钽剥离。最后，通过纯化溶液的沉淀制备了 > 98% 的纯铌氧化物和富含 Ta 的混合氧化物。29 M 萃取剂。用 0.5 M 硝酸和草酸的混合物从负载的有机溶液中选择性地剥离铌，而用高浓度硝酸 (1 M) 实现钽剥离。最后，通过纯化溶液的沉淀制备了 > 98% 的纯铌氧化物和富含 Ta 的混合氧化物。29 M 萃取剂。用 0.5 M 硝酸和草酸的混合物从负载的有机溶液中选择性地剥离铌，而用高浓度硝酸 (1 M) 实现钽剥离。最后，通过纯化溶液的沉淀制备了 > 98% 的纯铌氧化物和富含 Ta 的混合氧化物。