To separate tantalum and niobium, slag is also used, mainly in the process of separating tin. Although these tailings contain only small amounts of niobium and tantalum, they are now regarded as the most important source of raw materials for these two elements. The ratio of Ta/Nb in these tin slag is also very different.
Usually, these two metals and their compounds are indirectly separated from raw materials containing very small amounts of tantalum and niobium, such as tin slag, by means of smelting metallurgical enrichment of these two elements. Only the synthetic tantalum/niobium concentrate obtained by this method can be used for economical wet chemical processing. In these tin slags there are also those that, like natural niobite, contain very little Ta/Nb ratio of tantalum, that is, they contain a small amount of tantalum, but are rich in niobium. For economic reasons, the usual hydrometallurgical treatment and separation processes cannot be applied to these slag, as these processes require that the Ta/Nb ratio of the concentrate used be at least 1:3.
The method is to treat raw materials containing tantalum and niobium, such as tin slag, niobium ore and/or concentrate, with pure hydrofluoric acid or a mixture of hydrofluoric acid and sulfuric acid, and first extract the acid solution with MIBK(methyl isobutyl ketone), where niobium and tantalum enter the organic phase together. Generally, the sum of transition metals is calculated in terms of their oxides and is expressed as "combined oxides" (abbreviated: "C.O"). At this time, niobium cannot be selectively re-extracted from the organic phase by inorganic acid or water as usual, but the ketone phase containing C.O can be steam distilled. This method shows that both valuable substances are transferred to the water phase in a highly concentrated form. At this time, tantalum can be selectively extracted from the water phase by fresh ketone (MIBK), while niobium remains in the water phase.
Therefore, the invention comprises a hydrometallurgical method for separating tantalum and niobium from raw materials containing tantalum and niobium by first treating them with pure hydrofluoric acid or a mixture of hydrofluoric acid and sulfuric acid, followed by extracting the fluorine complex of tantalum and niobium in the treatment solution with methyl isobutyl ketone solvent, and steaming the organic ketone phase containing tantalum and niobium. Tantalum can be selectively extracted from the newly generated water phase with fresh methyl isobutyl ketone, while niobium remains in the water phase.
