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UBC Theses and Dissertations

Gold extraction via high-temperature chlorination Kumar, Rishu


This study explored a pyrometallurgical approach for gold extraction, utilizing chlorine gas as the chlorination agent. This high-temperature chlorination process offers distinct advantages in gold recovery. A thorough investigation into key process parameters, including chlorine partial pressure, gold particle size, temperature, and reaction time, was conducted to assess its feasibility and efficiency. Under optimal experimental conditions, remarkable gold recoveries of up to 98% were achieved. These optimal conditions were identified as follows: a chlorine gas flow rate of 60 ml/min (equivalent to a chlorine partial pressure of 0.6 atm), gold particle size within the range of 53 to 75 µm, a chlorination temperature of 1000°C, and a chlorination duration of 1 hour. Furthermore, a comprehensive kinetic analysis of the gold chlorination process was undertaken to gain a fundamental understanding of the reaction rates. This investigation employed two distinct approaches: model-free and model-fitting methods. These approaches were applied at various processing times and temperatures to provide a holistic understanding of the chlorination kinetics. Based on the activation energy values obtained from both methods, the one-dimensional diffusion model emerged as the most suitable kinetic model. The activation energy values, ranging from 18 to 24 kJ/mol, indicate that diffusion control mechanisms govern the chlorination reactions. In summary, this study showcases the potential of the high-temperature chlorination process for efficient gold extraction. The optimized conditions and the insights gained into the kinetics of the chlorination reactions contribute to the understanding and advancement of this promising method for gold recovery.

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