Roasting and chlorine leaching of gold-bearing refractory concentrate: Experimental and process analysis |
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Authors: | Ida De Michelis Agostino Olivieri Stefano Ubaldini Francesco Ferella Francesca Beolchini Francesco Vegliò |
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Affiliation: | 1. Department of Chemistry, Chemical Engineering and Materials, University of L’Aquila, L’Aquila 67040, Italy;2. Institute of Environmental Geology and Geoengineering, CNR Via Bolognola, Roma 700138, Italy;3. Department of Marine Sciences, Polytechnical University of Marche, Via Brecce Bianche, Ancona 60131, Italy |
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Abstract: | This paper deals with gold extraction from a refractory concentrate by chlorine leaching. The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentration. The oxidized material is treated by leaching with brine. After gold adsorption/reduction onto activated carbon, iron and base metals can be precipitated by NaOH. Roasting tests show the necessity to carry out a thermal pre-treatment at least at 550 °C to obtain a reduction of sulfur and mercury in the material (50% and 90%, respectively). Highest gold extraction yield (around 93%) is obtained in the leaching test performed with material sample treated at 650 °C. This result confirms the necessity to optimize the thermal pre-treatment to improve Au recovery and to reduce chlorine consumption. A comparison with conventional cyanidation confirms that chlorination could be an useful alternative: in fact, gold extraction yield is quite low: 57% in non-pre-treated material and 25% in pre-treatment material. |
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Keywords: | Gold ores Refractory ores Leaching Chlorine |
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