Tantalum/niobium ores flotation

Oxalic acid is used as the depressant of various silicates. Meantime, it is also applied in the flotation separation of rare-earth mineral, tantalum-niobium ore, monazite, and cassiterite. 

Bulatovic, S., Tantalum niobium flotation from complex ores, Report of Investigation, p. 185, 1989. 

In the past, most of the rutile was produced from heavy mineral sands using physical concentration, involving gravity, magnetic separation and electrostatic concentration. The physical preconcentration method cannot be applied to a fine heavy mineral sand or hard ore. In some cases, heavy mineral sand contains zircon, tantalum, niobium and other heavy minerals, where in most cases a flotation method is used. 

There are approximately 130 different minerals that contain tantalum and niobium, from which about 80 are Ta/Nb only. The other minerals contain tantalum and niobium in the form of impurities. There is very little information available on beneficiation of Ta/Nb-containing ores. In actual practice, there are three basic methods for production of Ta/Nb concentrate (a) physical preconcentration, (b) combination of physical preconcentration and flotation and (c) direct flotation. In most cases, Ta/Nb ores contain significant quantities of zircon and rare earth ores (REO). 

The ore used in this example contained a mixture of pyrochlore and columbite as the major niobium minerals. The tantalum is mainly associated with columbite. The major gangue minerals present in this ore were soda and potassium feldspars with small amounts of mica and quartz. Beneficiation of this ore using cationic flotation, normally employed for flotation of niobium, was not applicable for this particular ore, since most of the mica and feldspar floated with the niobium and tantalum. The effect of amine on Ta/Nb flotation is illustrated in Figure 23.9. The selectivity between Ta/Nb and gangue minerals using a cationic collector was very poor. 

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