Flotation of niobium

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. 

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. 

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. 

The results obtained indicated that cationic flotation of pyrochlore was not successful. Dispersant AQ4 has a pronounced effect on niobium metallurgical results. Dispersant/ depressant AQ4 is composed of the following individual reagents 60% orthodihydrox-ybenzene (Catacol), 30% low-molecular-weight acrylic acid (Accumer 2400) and 10% hexametapho sphate. 

The AQ4 provides excellent pulp dispersion and slime depression during niobium flotation. The niobium grade-recovery relationship using different levels of AQ4 is shown in Figure 22.6. 

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

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 Ta/Nb flotation was accomplished using collector RS702. This collector is composed of amine acetate, phosphoric acid esters and hydroxamate. Collector RS702 is a powerful collector, capable of floating a variety of niobium minerals that are contained in the flotation feed. Metallurgical results obtained from a continuous locked-cycle test are shown in Table 23.14. 

According to the report of lU. G. Pukin, salamide can be used as the depressant of feldspar in the flotation of tantalum niobium. Sulfosalicylic acid and alizarin red can depress the valuable mineral to achieve the reverse flotation of feldspar in the separation of spodumene and tantalum niobium. 

The most important tin mineral is cassiterite (Sn02). Theoretically, the tin content of cassiterite is 78%. However, in the majority of cases, cassiterite contains impurities and the tin content may vary from 65% to 78%. The major impurities of cassiterite include tantalum, niobium, titanium and other elements, usually in the form of solid solutions. The impurities in the cassiterite often have a pronounced effect on flotation properties of cassiterite. 

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