Abstract
The mineralogy and liberation characteristics of the comminuted Penouta leucogranite host of the Sn-Ta ore were determined. Grinding developed by a combination of high-pressure grinding rolls (HPGR) followed by a ball mill (BM) was compared with a single ball mill process. The mineral characteristics of the grinding products were analyzed using a Tescan Integrated Mineralogical Analyzer (TIMA-X) and X-ray powder diffraction (XRD). The ore contains 103 ppm of Ta and is mainly composed of quartz, albite, microcline, muscovite, and kaolinite. Nb, Ta-rich minerals are columbite-(Mn) and tantalite-(Mn), as well as minor microlite and wodginite. The liberation in the product is high in the size fraction of less than 250 µm (51–52 wt % for columbite-group minerals (CGM) and 74–80 wt % for cassiterite) and reduced in larger particles (8.8–17 wt % for CGM and 28–37 wt % for cassiterite). The recovery in the −250 µm fraction was high, while in the larger fraction it is limited, remaining up to 80 ppm in some tailings. The combined use of HPGR and a BM reduces the particle size distribution of the product and, thus, increases the liberation of the ores. Smaller fractions can be treated directly using gravity methods; however, particles of a size greater than +250 µm should be ground more.
Highlights
Tantalum has a great relevance nowadays for its use in modern technologies, is difficult to substitute using other metals [1], and is considered a critical metal [2,3,4,5]
The whole rock sample and the Sn, Ta, Nb, U, and Th of all the grinding products were analyzed at ALS laboratories by X-ray fluorescence (XRF) using glass beads, followed by acid digestion and Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
Mineralogy was determined by optical microscopy, X-ray powder diffraction (XRD), scanning electron microscopy with energy-dispersive spectral analysis (SEM–EDS) in the back-scattered electron mode (BSE), and electron microprobe analyzer (EMPA)
Summary
Tantalum has a great relevance nowadays for its use in modern technologies, is difficult to substitute using other metals [1], and is considered a critical metal [2,3,4,5]. Europe needs to have greater self-sufficiency in the exploitation of strategic metals; for this reason, the exploitation of low-grade deposits should be considered. This is the case with the tantalum ore deposits in Europe. Low-grade tantalum ore deposits in rare metal granites are relatively abundant in the western part of Europe. In order to make the exploitation of these deposits economically viable, their processing needs to be optimized To this end, it is crucial to know the mineralogical and textural characteristics of the ores in order to be able to carry out their liberation in the most efficient way
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