Estudi per desenvolupar una proposta per la remediació in situ d'aigües àcides de mina

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Estudio para el tratamiento de las aguas ácidas por neutralización-precipitación en interior de la mina Santa Fé, Bolivia

Como consecuencia de la intensa actividad minera que se ha llevado a cabo en Bolivia durante todos estos años se han producido enormes problemas de contaminación ambiental.no de los problemas más importantes ocasionados es la acidificación de las aguas, constituyendo el llamado drenaje ácido de minas (DAM), con la consecuente disolución de metales pesados. Este estudio pretende desarrollar una propuesta para el tratamiento físico-químico por neutralización-precipitación en interior de la mina Santa Fe. Después de la caracterización química y las pruebas de sedimentación se determina el diseño del sedimentado r utilizando una de las galerías ya explotada. Los lodos serán dispuestos en tajos abiertos de manera secuencial tratados mediante un proceso de solidificación que dotará de estabilidad física a los lodos y de mayor estabilidad a la galería.Postprint (published version

Mineralogical characterisation of tantalum ores for the optimization of their processing

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Nb-Ta oxide minerals of alluvial placers from the Sunsás belt, precambrian shield of Bolivia

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Textural and mineral-chemistry constraints on columbite-group minerals in the Penouta deposit: evidence from magmatic and fluid-related processes

The Penouta Sn-Ta deposit, in the northwest of Spain, is a greisenized granitic cupola where Ta minerals occur mainly as disseminations in a leucogranite body intruded in Precambrian–Lower Cambrian gneisses and mica-schists. This leucogranite is a medium- to fine-grained inequigranular rock consisting mainly of quartz, albite, K-feldspar and muscovite. Accessory minerals are mainly of spessartine, zircon, cassiterite, Nb-Ta oxides, monazite, xenotime, native bismuth and pyrite. The alteration processes were mainly albitization, muscovitization and kaolinitization. This leucogranite is peraluminous and P-poor, with 0.03–0.07 wt.% P2O5, 900–1500 ppm Rb, 30–65 ppm Cs, 120–533 ppm Li, 80–140 ppm Ta, 51–81 ppm Nb and up to 569 ppm of Sn. Mineralogical characterization of Nb-Ta oxide minerals was determined by X-ray diffraction, scanning electron microscopy, electron microprobe analysis and mineral liberation analysis. Mn-rich members of the columbite-group minerals (CGM) are the most common Ta-bearing phases, but microlite, wodginite, tapiolite and Ta-rich cassiterite occur also. CGM crystals are commonly zoned concentrically, with a Nb-rich core surrounded by a Ta-rich rim, with a sharp boundary between them. Convoluted zoning occurs also. Dissolution textures resulting from the corrosion of columbite and tantalite rims, in particular, are common. TheMn/(Mn + Fe) ratio varies between 0.33 and 0.97 and the Ta/(Ta + Nb) ratio between 0.07 and 0.93. Wodginite and microlite formed as late replacements of CGM and occur associated with tantalite and cassiterite. Subhedral to anhedral cassiterite crystals, usually up to 200 µmacross, occur in two generations: the earlier one is Nb,Ta-poor whereas in the later generation, the Ta content can reach >9 wt.%of Ta2O5 and 1.7 wt.%of Nb. The presence of a fluid phase in the apical zone of the granite, probably related to the separation of a fluid/vapour of the melt, could explain the sponge-like textures, the Ta enrichment associated with these textures, the occurrence of Taenriched mineral phases (microlite and wodginite) and their common interstitial character.Peer ReviewedPostprint (published version

Optimization of the tantalum ore production by control the milling process

Tantalum is a strategic metal with multiple applications in the new technologies. Tantalum deposits are scarce in EU. Thus, more efficient extracting processes are necessary to contribute to major European independency on these critical raw materials. Tantalum occurs mainly in pegmatites and leucogranite deposits and its placers. Europe does not produce tantalum; however, several deposits are susceptible of being exploited if technologies of processing are improved. This work is part of the Optimore Project which aims to develop modelling and control technologies, using advanced sensing and advanced industrial control by using artificial intelligence techniques, for the more efficient and flexible tantalum and tungsten processing from crushing to separation process. In this paper, a preliminary study of characterization of tantalum ores from leucogranite and alluvial deposits is presented to be used as a base for design the milling experiments to optimize the tantalum recovering during the processing. In the ore deposits tantalum appears in solid solution with niobium in complex oxides, which forms low grade aggregates which need to be processed by means of a separation process. Tantalum ores characterised here belong to alluvial placers of pegmatitic origin located in the Bolivian Amazon Craton and to leocogranites of Penuota, in Spain. Ta bearing minerals of the Bolivian placers are mainly from the columbite group minerals. In Penouta microlite is abundant and often it has a zoning characterised by a Nb-rich core followed by a Ta-rich rim of several cm in thickness.Peer ReviewedPostprint (published version

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Una forma insòlita d'elaborar el vi: noves trovalles de tines enmig de la vinya

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2008. Les barraques de vinya són uns elements molt típics del paissatge de la comarca del Bages on anys enrere era el monocultiu propi de la comarca. S’han estudiat els fonaments arquitectònics que confereixen l’estabilitat d’aquestes construccions de pedra seca que, malgrat l’aparent simplicitat i fragilitat, havien de tenir una complexitat en l’estructura arquitectònica per haver aguantat des del segle XIX. També s’han estudiat altres construccions de pedra seca pròpies de la vinya, tals com la tina

Projecte de cooperació a la mineria artesanal, seguretat i salut a la regió del Triángulo Minero

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