Modelling of liberation in ta- and w-rich minerals
- Autores: Sarbast Ahmad Hamid Hamid
- Directores de la Tesis: Maria Pura Alfonso Abella (dir. tes.), Josep Oliva (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Juan María Menéndez Aguado (presid.), Lluís Sanmiquel Pera (secret.), Miquel Rovira Boixaderas (voc.)
- Programa de doctorado: Programa de Doctorado en Recursos Naturales y Medio Ambiente por la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
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
