Multielemental analysis of tantalum ores by ICP-OES


                 Lucie ŠIMONÍKOVÁ^1, Jan Loun^2, Karel NOVOTNÝ^1, Viktor KANICKÝ^1


^1Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech
Republic

^2KYOECERA AVX Components s.r.o., Dvořákova 328, 563 01 Lanškroun, Czech Republic

Email of presenting author:


The main goal of this work is to design an analytical procedure for determining the content of
tantalum and niobium in ore concentrates with variable content of these elements. In nature,
tantalum deposits rarely have a concentration of more than 0.05 wt. % Ta[2]O[5] (usually 0.01 -
0.04 wt.%). Primary Ta (and Nb) mineralization is mainly related to igneous rocks, socalled rare
element pegmatites. Moreover, depending on the nature of the deposit the ore may contain a wide
range of accompanying minerals. For the evaluation of ore from an economic point of view, the
tantalum oxide content determination is the most important. Nevertheless, knowledge of the
concentrations of accompanying elements, such as tin, silicon, uranium, thorium, titanium,
manganese, sulfur, sodium, potassium, is crucial for choosing the technological procedure of
further processing [1,2].

The following types of decompositions have been previously developed and can be found in the
available literature: 1) microwave decomposition in various mineral acids; 2) alkaline melting; 3)
decomposition with HF; 4) melting with Na[2]O[2]. Nevertheless, some of these decomposition methods
do not reliably achieve 100% recovery, are time-consuming, the used chemicals contain also the
elements of interest or there is an increased risk of contamination.

Melting with lithium borax and subsequent dissolution in a mixture of acids has been found as an
optimal method for tantalum ores sample preparation with variable content of the abovementioned
elements. Depending on the origin and type of the ore the contents of Ta, Nb, Sn, Si, Ti, Mn, S,
Na, K and other elements were determined by ICP-OES. The optimization of the decomposition method
was verified using the standard X1808 or by the samples analyzed in an accredited laboratory by the
XRF method. Verification of the results by the sum to 100% was also applied.


References

[1] F. Fairbrother, Chemistry of Niobium and Tantalum. Elsevier, Amsterdam, (1967) 243 s

[2] J.M. Fetherston, Tantalum in Western Australia. Western Australia Geological Survey, Mineral
Resources Bulletin 22, (2004)162 s


Acknowledgements

The work was supported by the project MUNI/A/1412/2021 of Masaryk University „Research of
geological, biological and advanced synthetic materials by analytical and physico-chemical
methods”.