Recovery of niobium during comprehensive processing of pyrochlore-monazite-goethite ores

Abstract

This paper looks at the pyrochlore-monazite-goethite ores of the Chuktukonsk deposit (0.98wt.% Nb2O5) and their processing with the help of acidbased (HNO3, H2SO4) and sulphatization techniques. Nitric-acid pressure leaching was found to be an efficient processing technique for this type of ore: ore size –0.074 mm; CHNO3 = 25%; CH2O2 = 5%; τ = 2 h; solid-to-liquid = 1:9; heat treatment mode: 1 h at 160 oC followed by 1 h at 230 oC. As a result, rare earth metals and manganese are leached to the solution while all of the contained niobium remains in the cake. Two different techniques were tested to recover niobium from the cake. One is based on the use of alkali (NaOH sintering), the other is an extractive leaching technique that combines acid leaching with liquid-liquid extraction of tributyl phosphate in one stage. It was established that niobium mi nerals can be efficiently decomposed when using a mixture of hydro fluoric and sulphuric acids with the concentrations of 4.08 and 8.46 mol/L, correspon dingly, as a leaching agent. At the weight ratio of 1:2:1 of the solid to aqueous to organic phase and after the slurry has been stirred intensively for 5 minutes, niobium fluorides, which form as a result of interaction between hydrofluoric acid and the cake components, can be recovered with a 50% solution of tributyl phosphate in octane. After that they transfer to an organic phase while impurities get accumulated in the solid residue. As niobium-containing cake has a high concentration of silicon, it is recommended to first remove silicon from the cake using a strong alkaline solution.

Technological assessment of prospects for processing of carbonatite weathering core to produce commercial niobium compounds

“…Высокая дисперсность монацита, минералов группы крандаллита, их тесные срастания с гидроксидами железа (для минералов группы крандаллита также с каолинитом и между собой), сложные типы срастаний пирохлора (коррозионные) с гидроксидами железа, повышенная хрупкость пирохлора, склонность к переизмельчению обуславливают невозможность использовать механические методы обогащения, и комплексное извлечение ценных компонентов из этих руд возможно гидрометаллургическими способами. Ниобий может быть извлечён из кека (1,6 % Nb2O5), полученного после автоклавного азотнокислотного вскрытия исходной руды [8], экстрактивным выщелачиванием [9]. Совмещение операций фторидно-сульфатного выщелачивания кека и жидкостной экстракции в одну стадию обеспечивает получение пентаоксида ниобия (87,9 % Nb2O5), соответствующего требованиям ТУ 1763-019-00545484-2000.…”