Liberation characteristics of Ta–Sn ores from Penouta, NW Spain

Abstract

The strategic importance of tantalum and its scarcity in Europe makes its recovery fromlow grade deposits and tailings interesting. In Penouta, the contents of Ta and Sn in old tailingsfrom an Sn mine are of economic interest. Due to the relatively low grade of Ta of around 100 ppm,a detailed study of the mineralogy and liberation conditions is necessary. In this study, the mineralogyand the liberation characteristics of Sn and Ta ores of the Penouta tailings were investigated andcompared with the current leucogranite outcropping ores. The characterization was conductedthrough X-ray diffraction, scanning electron microscopy, and electron microprobe. In addition,automated mineralogy techniques were used to determine the mineral associations and liberationcharacteristics of ore minerals. The grade of the leucogranite outcropping was found to be about80 ppm for Ta and 400 ppm for Sn, and in the tailings used for the liberation study, the concentrations ofTa and Sn were about 100 ppm Ta and 500 ppm Sn, respectively. In both, the leucogranite outcroppingand tailings, the major minerals found were quartz, albite, K-feldspar, and white mica. Ore mineralsidentified were columbite-group minerals (CGM), microlite, and cassiterite. The majority of CGMexamined were associated with cassiterite, quartz, and muscovite particle compositions and cassiteritewas mainly associated with CGM, quartz, and muscovite. The liberation size was 180µm for CGM.