Browsing by Autor "Pura Alfonso"

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Mineral chemistry of In-bearing minerals in the Santa Fe mining district, Bolivia
(National Geology and Mining Service, 2018) Abigail Jiménez–Franco; Pura Alfonso; Carles Canet; Juan Elvys Trujillo
The Santa Fe mining district is located in the Central Andean tin belt of Bolivia and contains several Sn-Zn-Pb-Ag deposits. From the economic point of view, the most important deposits of the district are Japo, Santa Fe and Morococala. Beyond the traditional metal commodities, the Central Andean Tin Belt could become an exploration target for indium, owing to the potential of the ore-bearing paragenesis with high concentrations of this technology-critical element. In the Santa Fe mining district, the ore occurs as two main types: (a) Sn-rich cassiterite-quartz veins, and (b) Zn-Pb-Ag veins with sphalerite, galena and stannite mineral phases. The In content in igneous rocks is between 1.5 and 2.5 ppm, whereas in the ore concentrate it attains up to 200 ppm. The 1,000×In/Zn ratio in concentrate ranges from 25 up to 4,000. Exceptionally high In values were found in sakuraiite from Morococala deposit (2.03 wt%). Sakuraiite in this deposit shows evidences for a link between stannite and kësterite trend of solid solutions. There is a noteworthy exploration potential for strategic metals in this district and even in similar deposits elsewhere in the Central Andean tin belt.
Mineralogical and thermal characterization of borate minerals from Rio Grande deposit, Uyuni (Bolivia)
(Springer Science+Business Media, 2015) Maite García‐Vallés; Pura Alfonso; Jony Roger Hans Arancibia; S. Martı́nez; David Parcerisa Duocastella
Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia
(Elsevier BV, 2013) Johanna Arancibia; Pura Alfonso; Maite García‐Vallés; S. Martı́nez; David Parcerisa Duocastella; Carles Canet; Francisca Moreno Romero
Optimizing Mineral Resources with Automated Mineralogy Techniques: The Case of Colquiri in the Central Andean Tin Belt
(Multidisciplinary Digital Publishing Institute, 2025) Pura Alfonso; Miguel Fernández Ruiz; Marçal Terricabras; Arnau Martínez; Maite García‐Vallés; Hernán Anticoi; María Teresa Yubero; S. Valls
Colquiri is one of several deposits from the Central Andean tin belt, where sphalerite and cassiterite are mined. Although this is a high-grade Zn-Sn deposit, processing results in a low overall yield, with significant amounts of zinc and tin being discarded as tailings. In this study, mineralogical research was conducted to identify the causes of the low yield, so that the flow diagram could be modified to improve recovery. Particle size was measured, and chemical and mineralogical analyses were performed using optical and electron microscopy and X-ray diffraction. The mineral chemistry of the ores was determined using electron probe microanalysis (EPMA), and mineral liberation analyses were performed to complete the characterization. Mineralization occurred in four stages: (1) formation of silicates and oxides; (2) main precipitation of sulfides, including pyrrhotite, sphalerite, and stannite; (3) precipitation of fluorite and the replacement of pyrrhotite by pyrite, which was then replaced by siderite; and (4) weathering of previously formed minerals. The run-of-mine material contains approximately 12 wt.% ZnO and 1.5 wt.% SnO2. The Zn concentrate contains up to 43.90 wt.% ZnO, and the Sn concentrate contains 52 wt.% SnO2. The final tailings still retain more than 3–4.5 wt.% ZnO and 1.2 wt.% SnO2. The average grain size of sphalerite is 200 µm, while that of cassiterite and stannite is 45 µm. The liberated fraction of sphalerite is 51.43%, and binary particles of sphalerite plus stannite account for 60 wt.%. Cassiterite is liberated at 54.68 wt.%. To increase the recovery of sphalerite (with stannite) and cassiterite, as well as the grade of the concentrates, it is necessary to reduce the particle size of the processed ores to less than 100 µm.
Process Mineralogy of the Tailings from Llallagua: Towards a Sustainable Activity
(Multidisciplinary Digital Publishing Institute, 2022) Pura Alfonso; Miguel Fernández Ruiz; Rubén Néstor Zambrana; Miquel Sendrós; Maite García‐Vallés; Hernán Anticoi; Nor Sidki-Rius; Antonio Salas
There are significant tin reserves in the dumps and tailings from Llallagua. Currently, this waste is being processed using gravity concentration or a combination of gravity concentration with a final stage of froth flotation. A process mineralogy study of the tailings and their products after processing in Llallagua was carried out to determine the failings of the processing system in order to contribute to designing an improved new processing scheme. The mineralogy of the feed tailings, concentrate, and final tailings was determined by X-ray diffraction, scanning electron microscopy, and mineral liberation analysis. The tailings were composed of quartz, tourmaline, illite, K-feldspar, plagioclase, cassiterite, rutile, zircon, and monazite. The concentrate essentially contains cassiterite (57.4 wt.%), tourmaline, quartz, hematite, rutile and rare earth minerals, mainly monazite and minor amounts of xenotime and florencite. The concentrate contained 52–60 wt.% of SnO2 and 0.9–1.3 wt.% REE. The final tailings contained 0.23–0.37 wt.% SnO2 and 0.02 wt.% of Rare Earth Elements (REE). Only 57.6 wt.% of cassiterite from the concentrate was liberated. The non-liberated cassiterite was mainly associated with quartz, tourmaline, and rutile. The average grain size of monazite was 45 µm and 57.5 wt.% of this was liberated. In other cases, it occurs in mixed particles associated with tourmaline, quartz, cassiterite, and muscovite. To improve the sustainability of this mining activity, the concentrate grade and the metal recovery must be improved. Reducing the particle size reduction of the processed tailings would increase the beneficiation process rates. In addition, the recovery of the REE present in the concentrate as a by-product should be investigated.
The role of cassiterite controlling arsenic mobility in an abandoned stanniferous tailings impoundment at Llallagua, Bolivia
(Elsevier BV, 2014) Francisco Romero; Carles Canet; Pura Alfonso; Rubén Néstor Zambrana; Nayelli Soto
Thermal behaviour of kaolinitic raw materials from San José (Oruro, Bolivia)
(Springer Science+Business Media, 2022) Pura Alfonso; L. A. Penedo; Maite García‐Vallés; S. Martı́nez; Adriana H. Martínez; Juan Elvys Trujillo