A Process Mineralogy Approach to Gravity Concentration of Tantalum Bearing Minerals

Abstract

Abstract:The historic Penouta mine in northwest Spain is the focus of efforts to extract tantalum from tin mining waste. This paper describes the characterisation of the tantalum mineralogy of waste material from the deposit. Characterisation was realised using quantitative mineralogy and geochemistry. This paper further identifies other phases of interest and investigates the potential for extraction using gravity separation techniques. The gravity concentrate obtained through these tests was analysed using quantitative mineralogy and electron probe microanalysis. Following characterisation of the sample material to identify the key Ta-bearing mineral phases and assess liberation, a series of gravity separation trials were conducted using Heavy Liquid Separation (HLS), Mozley table, Knelson concentrator separation and shaking table. The laboratory shaking table used to conduct a rougher test and a rougher/cleaner test to simulate a spiral-table circuit using the Penouta material. Mass balance calculations were carried out to calculate the contained metal content of the feed material and concentrate products in order to assess recovery rates for Ta, Sn and Nb across a range of grains sizes. Ta was found to be present predominantly in the solid-solution columbite-group mineral, along with minor Ta present as microlite and as impurities within cassiterite. It was found that over 70% of the Ta is contained within the −125 µm fraction, with the Ta-bearing minerals tantalite and microlite being closely associated with quartz. Mozley table separation resulted in recoveries of 89% Ta and 85% Nb for the −125 µm fraction. The Knelson Concentrator trial was carried out on the −625 µm size fraction, thereby eliminating low grade material found in the coarsest fractions. Size analysis of the recovery rate for each product, shows that the Knelson concentrator is most efficient for recovery of −125 µm particles.

Liberation Characteristics of Ta–Sn Ores from Penouta, NW Spain

“…Regarding the concentration, this is justified by the higher density of Ta-rich minerals compared to Nb-rich materials, which are easier to concentrate by gravimetric methods. Similar results were achieved for the gravity concentration of fine tailings in previous studies [35], in which the higher recovery of tantalum was attributed to larger tantalite particles; however, in this case, no evidence of this size difference was shown.…”

“…The size of particles is very important to the efficiency of the processing method. Froth flotation has a low level of efficiency with particles smaller than 20 µm [61], and abundant problems are produced when the method is used with fine particles [62], and loss efficiency in concentrate particles under 50 µm in size [35,61,63]. In the Penouta leucogranite and tailing concentrates only 0.28 wt% and 0.17 wt% of cassiterite, respectively, are present in particles of less than 20 µm in size, and its content of cassiterite in particles under 50 µm is also small enough that the exclusive use of gravity methods may be feasible.…”

“…Some of the ore liberation characteristics from the Penouta leucogranite have been reported previously using quantitative mineralogy TESCAN [32,33] as well as less expensive techniques, such as scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) [34]. Gravity separation studies focussed in a particular sector of the Penouta tailings have been reported [35], as well as studies on metallurgical treatments [36]. These studies, along with the previous studies on crushing [37] and milling [32,38], provide a broad understanding of the Penouta ore processing.…”

Quantitative Mineralogical Comparison between HPGR and Ball Mill Products of a Sn-Ta Ore

“…The mineralogy of the open pit was recently reported in ore deposit studies [33][34][35]. The process mineralogy study of the largest tailing is presented in this volume [36].…”

Understanding Mineral Liberation during Crushing Using Grade-by-Size Analysis—A Case Study of the Penuota Sn-Ta Mineralization, Spain

“…The case study was performed on two~1 ton samples from the Penouta open pit mine, collected by university of Centres Cientifics i Tecnològics de la Universitat de Barcelona during January 2015, as a part of a multi-partner research collaboration (OPTIMORE, project number 642201) [25,[28][29][30][31][32]. Due to potential mineralogical variations, samples of the mineralized leucogranite were collected from different parts of the open pit.…”