Niobium ores, flotation

For this reason, we consider it hardly possible to cite all of the publications. Let us focus only on the following examples. Hydroxamic acids have already been for a long time subject of the classical analytical chemistry. In [71], the possibility of using these compounds in flotation of rare-earth minerals is shown. It has been concluded that on a mineral surface cerium chelates are formed. Besides, chemisorption is accompanied by a physical multilayer adsorption of hydroxamic acid derivatives formed by reaction with cations in the water phase. A number of chelate-forming compounds including hydroxamic acids has been tested in flotation of niobium ores [72]. The best results are obtained when using alkyl phosphonic acids. Chemisorption mechanism and the structure of the surface compounds are established by spectroscopic methods. 

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. 

Figure 22.3 Effect of sodium oleate on flotation of niobium from pegmatite ores.

Pavlor, D.A., Flotation of Niobium from Pegmatitic Ores, Tsvetnie Metally, No. 8, 1976. 

Bulatovic, S., Research and Development of Niobium Flotation from Pegmatite Ore, SGS Report of Investigation, 2007. 

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 results showed that amines normally used for pyrochlore flotation did not work for flotation of Ta/Nb. Therefore, collector selection is very dependent on the type of niobium minerals present in the ore. 

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. 

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. 

The ore is ground to a state where 90 % is smaller than 74 pm. pH is regulated and depressants are applied for the gangue." A collector is applied to amass the valuable minerals in the foam. Depressed iron oxide minerals and sihcate minerals remain at the bottom of the flotation cells and are removed for iron beneficiation and niobium recovery. 

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