Speeding Up the Analytical Workflow for Coltan Fingerprinting by an Integrated Mineral Liberation Analysis/LA‐ICP‐MS Approach

Abstract

Coltan (the African trade name for columbite‐tantalite, a tantalum ore) is one of several raw materials that finance the civil wars in the eastern provinces of the Democratic Republic of the Congo. To improve the transparency along the tantalum trade chain, a ‘certificate of origin’ for so‐called ‘conflict minerals’ has been recommended by the United Nations. Accordingly, the German Federal Institute for Geosciences and Natural Resources (BGR) has developed an analytical fingerprint procedure for coltan. Mineral formation age, modal mineralogy and chemical composition are important fingerprint parameters. The original workflow to obtain these parameters was streamlined and is now based on mineral liberation analysis and LA‐ICP‐MS. The use of an ICP‐MS instrument with a detector system covering an extended linear dynamic range and the application of an internal standard‐independent calibration strategy allowed data for major and trace element determination and mineral formation age estimates to be obtained simultaneously. The analytical results of this new approach were compared with analytical techniques of the original workflow and showed excellent agreement in terms of mineralogical and chemical characterisation and mineral formation age of coltan samples. Within a test, samples of different origin were allocated correctly and simple, binary mixtures were also identified successfully.

Petrogenesis of alkaline basalt-hosted sapphire megacrysts. Petrological and geochemical investigations of in situ sapphire occurrences from the Siebengebirge Volcanic Field, Germany

“…The signal was tuned to obtain maximum sensitivity for 238 Jackson et al (2004) to have a TIMS age of 608 ± 0.4 Ma. Isotopic ratios were corrected for ablationinduced elemental fractionation offset between zircon matrix and columbite offset between zircon matrix and columbite matrix using a columbite-tantalite solid solution (Coltan 139) from Madagascar that is being used as an in-house standard for coltan LA-ICP-MS analyses by the Federal Institute for Geosciences and Natural Resources, Germany (Gäbler et al 2011). The usability of Coltan 139 as a matrix matching standard for Columbite Group Mineral LA-ICP-MS U-Pb dating was recently demonstrated by Che et al (2015).…”

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

“…Data reduction was handled with a software tool, which was implemented in JAVA using the libraries JFreeChart, commons Math and POI [32]. The signals for background and sample measurements are time-resolved, and therefore, selected time intervals are integrated for the blank and sample signals.…”

“…The following isotopes have been analyzed: U in LR and 12 C, 24 Mg, 27 Al, 29 Si, 31 P, 32 S, 44 Ca, 45 Sc, 47 Ti, 51 V, 52 Cr, 55 Mn, 56 Fe, 59 Co, Th in MR. For all elements, both secondary electron multiplier (SEM) and Faraday detector are used, depending on the count rate.…”

Mineralogical and microtextural parameters in metals ores traceability studies

“…The development of the 18 O/ 16 O isotopic identity card for emeralds helps to distinguish the source of a large number of high quality emeralds (Giuliani et al, 1998 b). Fingerprints of coltan can be determined to find the place of origin of the mineral (Melcher et al, 2008 a andb, 2013;Gäbler et al, 2011Gäbler et al, , 2013Savu-Krohn et al, 2011). A similar need sometimes arises during mineral processing when multiple sources are used.…”

“…It is also a growing concern for the "citizen-consumer", who needs to be sure that theses items have not been produced contrary to his ethical or moral values (for example involving child labor, destruction of non-renewable resources, untreated pollution, ...). To avoid parallel markets of certain mineral resources, solutions have been proposed to locate the extraction sites of these resources for diamond via the Kimberley Process (www.kimberleyprocess.com), for emeralds (Giuliani et al, 1998 a and b), sapphire (Giuliani et al, 2005), ruby (Giuliani et al, 2005) and "coltan" (Melcher et al, 2008 a andb, 2013;Gäbler et al, 2011Gäbler et al, , 2013Savu-Krohn et al, 2011). A chain of control and certification has been set up by the diamond producer countries under the supervision of international experts.…”