Estudio integral del comportamiento de la cianuración de plata en concentrados minerales
This thesis shows an integral study of cyanide leaching of the silver contained in two concentrates (Real del Monte and Las Torres). This work was developed applying electrochemical techniques, leaching in stirred batch reactors and mathematical model simulations. Despite the fact that both concentr...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2003 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:sq87bv148 |
| Acceso en línea: | https://doi.org/10.24275/uami.sq87bv148 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Leaching info:eu-repo/classification/LEM/Lixiviación info:eu-repo/classification/LEM/Silver info:eu-repo/classification/LEM/Plata info:eu-repo/classification/cti/7 |
| Sumario: | This thesis shows an integral study of cyanide leaching of the silver contained in two concentrates (Real del Monte and Las Torres). This work was developed applying electrochemical techniques, leaching in stirred batch reactors and mathematical model simulations. Despite the fact that both concentrates contained the same total amount of silver, it was found, by leaching, that the silver velocity extraction was faster and more complete in the Real del Monte as compared to the Las Torres concentrate. SEM analysis applied to the concentrates revealed the presence of just one mineralogical phase in Real del Monte and four in Las Torres. With respect to the leach residues, in the first concentrate; silver phases were not detected, while in the second case refractory phases still remained (three of four phases). In order to establish a strategy to quickly evaluate the degree of refractoriness of the concentrates, a voltammetric study of the different concentrates was performed, using carbon paste electrodes. This method was applied both to the concentrates (Real del Monte and Las Torres) as well as to high purity phases: one in silver sulfide and the other in iron sulfide. It was found that, even though the amount of silver was small compared to the quantity of iron contained in the concentrates, it was possible to distinguish the leachable and refractory silver phases by applying electrochemical techniques. Also, it is possible to identify the influence of iron sulfide in these concentrates. In other hand, silver sulfide leaching was described using a mathematical model, adjusting just one kinetic parameter for all of the leaching experiments performed. This parameter was the fourth Damnköhler number, which was evaluated from the model and used to calculate the silver leaching velocity in the cyanide systems. At the same time, the oxidation velocity of silver sulfide was determinated using both the Evans’ diagrams and polarization curves. The reaction velocity values obtained through the use of the Evans’ diagrams were compared to that estimated from the leaching model, at the same conditions. Both results differed by three orders of magnitude (higher in the case of the Evans’ diagrams). This huge difference was due to the fact that the silver sulfide oxidation and the oxygen reduction, obtained electrochemically in separate experiments, modify the interfacial pH in a different manner that when both processes (redox) occur simultaneously (leachings). An electrochemical study was applied to study the oxygen reduction, in the presence of the concentrate and the oxidation of this in the presence of oxygen (polarization curves), in order to simulate the leaching processes. Despite this, the value of the reaction velocity value resulted two orders of magnitude higher than that obtained in the leaches (model). This behaviour indicates that the electrochemical methods still do not consider the entire complex phenomenon which occurs during the leaching process. The integral study developed in this work established the importance of performing a combined analysis including the experimental results (electrochemical and leaching) and the model, in order to complete a phenomenological study of the behaviour of silver contained in each sulfide concentrate. |
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