Wolframite- and scheelite-bearing carbonate rocks of the Nock mountains, Austria: A new type of tungsten mineralization in the Eastern Alps

Neinavaie, Hassan; Thalmann, F.; Ataii, B.; Beran, A.

doi:10.1007/bf00206716

Cited by 5 publications

(1 citation statement)

References 15 publications

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“…They can be distinguished from skarn deposits which are largely controlled by the composition of the host rock lithology and are assumed to be epigenetic. Strata bound tungsten mineralization occurs within iron-magnesite and dolomitic marbles in the Eastern Alps (Neinavale et al, 1989). Many strata bound tungsten occurrences appear to have been affected by later mobilization and reconcentration and therefore their syngenetic origin is questionable (Werner et al, 1998).…”

Section: Stratabound Depositsmentioning

confidence: 99%

Modelling of liberation in Ta- and W-rich minerals

Hamid

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With the general trend across all commodities towards the treatment of lower grade and medium grade ores, it is becoming increasingly important to develop the proper design for comprehensive mineralogical characterization and a complete procedure based on image analysis and grade distribution is proposed for the measurement of the liberation in the particles to reach the mineral liberation modeling. This thesis aims to develop an appropriate methodology to characterize complex low-grade Ta and medium grade W ores for the purpose of developing the most appropriate physical separation strategy. As result of this investigation a methodology is proposed for the mineralogical characterization and it consists of three different levels of characterization using different analytical techniques. Level 1, the simplest (which included chemical analysis, XRD, optical microscopy, SEM, and EMPA), was applied to Penouta and Mittersill ores and successfully characterized the mineralogy. Level 2, which included mineral characterization of the processed ores, and were XRD, SEM, and EMPA were needed for ores. The ores required the added sophistication of Level 3. In addition to the techniques of Level 1 and Level 2, Level 3 included the use of chemical analysis and automated SEM to estimate the mineralogical attributes of the ores. The insights from the mineralogical characterization were then used to inform the physical separation testing that was undertaken, for example, selective or bulk concentration. These results, together with the mineralogical characterization, indicated that selective gravity separation would be an appropriate processing route for this ore. The fine-grained Ta minerals required a P80 of about 100 µm. The final flow sheet produced a rougher concentrate that contained 103 ppm of Ta, at a recovery of 52%. In the Mittersill ore, the majority of the scheelite (>99%) was contained in hornblende, which itself represented approximately 33% of the ore. A bulk separation strategy using shaking table and the introduction of grinding to generate a P80 of 150 µm, was necessary to recover scheelite minerals to achieve a rougher concentrate of 2260 ppm W at a recovery of 87%. The mineralogical characterization of Mittersill, during which an association was found between scheelite and quartz, accounting for more than 17% of quartz in this ore with most of the remainder occurring as fine-grained quartz helped to guide the mineralogical characterization. This work describes a method for determining the downstream milling energy requirements for the mill products based on a Bond mill test performance. The grade distribution of particles at a given size fraction was calculated using a predictive liberation model. The recovery of particles in size/grade classes, image analysis using mineral liberation analysis (MLA), and function calculations were implemented for the modeling of the liberation. By describing the size, grade, and recovery data of particles in size/grade classes, a technique for the measurement of distribution functions was developed that relates beta distribution, a model for the function based on the incomplete beta function, and a solution to produce liberation modeling. It was shown that the predicted results agreed well with the observed results. The model was implemented in MATLAB, a simulation model, with King’s solution to the beta distribution function model that includes the liberation distribution Como indica la tendencia general en todos los productos hacia el tratamiento de minerales de leyes baja y media, se está volviendo cada vez más importante desarrollar diseños adecuados para una caracterización mineralógica integral. En este caso se propone un procedimiento completo basado en el análisis de imágenes y la distribución de leyess para la medición de liberación en las partículas, con el objetivo de alcanzar el modelo de liberación mineral. El objetivo de esta tesis es desarrollar una metodología adecuada para caracterizar los minerales complejos de Ta de baja y mediana ley con el fin de desarrollar estrategias de separación física más adecuada. Como resultado de esta investigación, se propone una metodología para la caracterización mineralógica y consta de tres niveles diferentes utilizando diferentes técnicas analíticas. El nivel 1, el más simple (que incluye análisis químicos, DRX, microscopía óptica, SEM y EMPA), se ha aplicado a los minerales de Penouta y Mittersill y se ha caracterizado correctamente la mineralogía. El nivel 2, que incluye la caracterización mineral del material ya procesado (entre ellos XRD, SEM y EMPA). Pa un mayor detalle de los minerales existentes, se requerían un nivel mas sofisticado de caracterización. Además de las técnicas del Nivel 1 y Nivel 2, el Nivel 3 incluía el uso de análisis químicos y SEM automatizado para estimar los atributos mineralógicos. Todos los datos obtenidos por la caracterización mineralógica fueron utilizados para supervisar las pruebas de separación física que se llevaron a cabo, por ejemplo, si se trata de una concentración selectiva o una concentración total. Estos resultados, junto con la caracterización mineralógica, indicaron que la separación por gravedad selectiva sería una ruta de procesamiento apropiada para este mineral. Los minerales Ta de grano fino requirieron un P80 de aproximadamente 100 µm. El diagrama de flujo final produjo un concentrado que contenía 103 ppm de Ta, a una recuperación del 52%. En el mineral de Mittersill, la mayoría de la scheelita (> 99%) estaba contenida en hornblende, que a su vez representaba aproximadamente el 33% del mineral. Fue necesaria una estrategia de separación a granel usando la mesa de sacudidas y la introducción de la molienda para generar un P80 de 150 µm, en la recuperación de minerales de scheelita para lograr un concentrado de 2260 ppm W con una recuperación del 87%. La caracterización mineralógica de Mittersill, durante la cual se encontró una asociación entre el scheelita y el cuarzo, representando más del 17% del cuarzo en este mineral, y la mayor parte del resto se produjo cuando el cuarzo de grano fino ayudó a guiar la caracterización mineralógica. Este trabajo describe un método para determinar los requisitos de energía de molienda aguas abajo para los productos de fábrica basados ¿¿en el rendimiento de la prueba de molturabilidad de Bond. La distribución en la leyes de las partículas en una fracción de tamaño dada se calculó usando un modelo de liberación predictivo. La recuperación de partículas por clases de tamaño / ley, fue desorrollado por medio de un MLA (Mineral liberatio analysis), desarrollando una técnica adaptando los datos del la miscroscopía con las funciones estadistica de ditribución beta. Los resultados coincidían con la modelización y se han obtenido los parametros de la distribución beta para los minerales de tantalio y tungsteno.

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Section: Stratabound Depositsmentioning

confidence: 99%

Modelling of liberation in Ta- and W-rich minerals

Hamid

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Polyphase stratabound scheelite-ferberite mineralization at Mallnock, Eastern Alps, Austria

Altenberger,

Krause,

Wintzer

et al. 2024

Miner Deposita

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A peculiar type of stratabound tungsten mineralization in metacarbonate rocks was discovered and explored at Mallnock (Austria) during the late 1980s. It is the only tungsten occurrence in the Eastern Alps in which scheelite is associated with wolframite (96 mol% ferberite). The tungsten prospect is located in the Austroalpine Drauzug-Gurktal Nappe System recording polyphase low-grade regional metamorphism. Raman spectroscopy of carbonaceous material yield maximum metamorphic temperatures of 296 ± 27 °C and 258 ± 27 °C, which are assigned to Variscan and Eoalpine metamorphism, respectively. Scheelite and ferberite occur as polyphase stockwork-like mineralization in Fe-rich magnesite in the northern ore zone (Mallnock North), whereas in the western ore zone (Mallnock West), scheelite-quartz veinlets are exclusively hosted in dolomitic marbles. LA-ICP-MS analyses of scheelite and ferberite yield low contents of Mo, Nb, Ta, and rare earth elements, but high contents of Na and Sr. Uranium is particularly high in scheelite (up to 200 µg/g) and makes this mineral a suitable target for U–Pb dating. In situ U–Pb dating of scheelite yielded an early Permian age (294 ± 8 Ma) for Mallnock West and a Middle Triassic age (239 ± 3 Ma) for Mallnock North. A monzodioritic dike close to Mallnock yielded a U–Pb apatite date of 282 ± 9 Ma and supports the polyphase formation of this mineralization. The U–Pb scheelite ages indicate that a model for tungsten metallogeny in the Eastern Alps must also consider remobilization of tungsten by metamorphic fluids. In the Alps, the Permian to Triassic period (ca. 290–225 Ma) is characterized by an overall extensional geodynamic setting related to the breakup of Pangea. Lithospheric thinning caused higher heat flow, low-P metamorphism, and anatexis in the lower crust, which led to enhanced crustal fluid flow in the upper crust. These processes were not only responsible for the formation of metasomatic hydrothermal magnesite and siderite deposits in the Eastern Alps but also for this unique magnesite-ferberite-scheelite mineralization at Mallnock.

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