Thesis EFECTO DE UN PRE-TRATAMIENTO QUÍMICO EN BASE A NaCI-H2SO4 Y REPOSO EN EL PROCESO DE LIXIVIACIÓN DE UN MINERAL CALCOPIRITICO DE BAJA LEY
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Date
2017
Authors
MONCADA BENAVIDES, PAULINA DEL PILAR
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Abstract
El presente trabajo tiene como objetivo principal determinar el efecto del pretratamientoquímico en un mineral de baja ley proporcionado por Minera Rio Tinto. Para ladeterminación de las condiciones experimentales su utilizó la técnica experimental deExtracción Máxima de Especies por Lixiviación Agresiva (EMELA) desarrollada por elDepartamento de Ingeniería Civil Metalurgia y Materiales.El pretratamiento químico se llevó a cabo bajo una dosificación de reactivos del 0, 20, 50,80 100% del consumo de ácido y a tiempos de reposo de 7 y 15 días. La adición de ácidosulfúrico y cloruro de sodio produce la formación de ácido clorhídrico in situ, lo quebeneficiaría la transformación de sulfuros de cobre refractarios a especies menas solublesen medios ácidos, generando así una lixiviación más rápida.La lixiviación del mineral pretratado se llevó a cabo bajo concentraciones de 0, 40 y 70 g/Lde Cl- a pH 1 durante 4 horas a 300 RPM.Los resultados muestran que las extracciones son inmediatas ya que luego de 15 minutosde lixiviación las extracciones permanecen constantes, lo que indicaría una disolucióninmediata de especies solubles en medio ácido. Al aumentar la dosificación de reactivoshasta 50% del consumo de ácido aumentan las extracciones, sin embargo, por sobreestos valores las extracciones se mantienen constantes. La mejor condición se presentópara el 50% del consumo de ácido a una concentración de cloruro en la solución lixiviantede 70 g/L, las recuperaciones fueron de un 41% aproximadamente.Los tiempos de pretratamiento no generaron un aumento considerable en lasextracciones, por otro lado, el llevar a cabo el pretratamiento bajo condiciones de bajaexposición a oxígeno generaron una disminución en la recuperación de unos 10 puntosporcentuales.Los análisis SEM se realizaron tanto al mineral de cabeza como a ripio y pretratamientode la mejor condición. El análisis del mineral de cabeza determina que la morfología delas partículas es de hojuelas, mientras que el análisis químico superficial muestra unabaja presencia de sulfuros de cobre en la superficie de las partículas y la alta presencia decomponente silíceos (matriz). Por otro lado, el mineral pretratado mostró una morfologíaun tanto porosa y con alta cohesión de partículas finas mientras que el mapeo deelementos demostró la presencia de calcopirita en transformación. Finalmente, el análisisde ripio con baja aireación en pretratamiento mostró la presencia de sulfuros de cobre en la superficie, lo opuesto al ripio con alta aireación en pretratamiento donde la presencia decobre fue nula. Ambos presentaron la precipitación de sal en la superficie, descartandoalgún tipo de precipitación de algún cloruro de cobre.De los experimentos adicionales, los resultados evidencian que la mejor extracción seobtiene para la lixiviación a 100 g/L de cloruro con previo pretratamiento químico del 50%del consumo de ácido con un tiempo de reposo de 7 días donde las extracciones de cobrefueron del 41%.Extracciones cercanas al 25% se obtuvieron al pretratar el ripio bajo una dosificación del50% del consumo de ácido, mientras que esta misma condición omitiendo la adición desal generó una disminución de la recuperación a un 3%. Finalmente, la extracción másbaja, de un 2%, se reportó para el experimento donde se lixivió el ripio a 70 g/L de cloruro.
The main objective of this work is to determine the effect of chemical pretreatment on alow grade mineral provided by Minera Río Tinto. For the determination of the experimentalconditions the experimental technique of Maximum Extraction of Species by AggressiveLeaching (EMELA) was used, which was developed by the Department of CivilEngineering Metallurgy and Materials.The chemical pretreatment was carried out under a reagent dosage of 0, 20, 50, 80 100%of acid consumption and at rest times of 7 and 15 days. The addition of sulfuric acid andsodium chloride results in the formation of hydrochloric acid in situ, which would benefit theconversion of refractory copper sulphides to soluble ores in acid media, thus generating afaster leaching.The leaching of the pretreated ore was carried out at concentrations of 0, 40 and 70 g/L deCl- at pH 1 for 4 hours at 300 RPM.The results show that the extractions are immediate since after 15 minutes of leaching theextractions remain constant, which would indicate an immediate dissolution of solublespecies in acid medium. By increasing the dosage of reagents up to 50% acidconsumption, the extractions increase, however, above these values the extractions arekept constant. The best condition was presented for 50% of the acid consumption at achloride concentration in the leaching solution of 70 g/L, the recoveries were about 41%.On the one hand the pretreatment times did not generate a significant increase in theextractions, on the other hand, carrying out the pretreatment under conditions of lowoxygen exposure generated a decrease in recovery of 10%.SEM analyzes were performed on mineral, pretreated ore and solid product of leaching.The analysis of the mineral determines that the morphology of the particles seems likeflakes, whereas the superficial chemical analysis shows a low presence of coppersulphides in the surface of the particles and the high presence of siliceous component(matrix). On the other hand, the pretreated mineral showed a porous morphology with highcohesion of fine particles, while the element mapping demonstrated the presence ofchalcopyrite transformation. Finally, the analysis of pretreated ore with low-aeration levelsin pretreated showed the presence of copper sulphides on the surface, and pretreated orewith high aeration the presence of copper was low. Both presented precipitation of salt atthe surface, ruling out some type of precipitation of some copper chloride. From the additional experiments, the results show the best extraction is obtained forleaching at 100 g/L with a previous chemical pretreatment of 50% acid consumption with arepose time of 7 days where the copper extractions were 41 %.Extractions close to 25% were obtained by pretreating the solid product of lixiviation undera 50% of acid consumption, while this same condition omitting the addition of saltgenerated a decrease of the recovery to 3%. Finally the lowest extraction, of 2%, wasreported for the experiment where the solid was leached at 70 g/L.Key words: EMELA, chemical pretreatment, pretreated ore, chloride.
The main objective of this work is to determine the effect of chemical pretreatment on alow grade mineral provided by Minera Río Tinto. For the determination of the experimentalconditions the experimental technique of Maximum Extraction of Species by AggressiveLeaching (EMELA) was used, which was developed by the Department of CivilEngineering Metallurgy and Materials.The chemical pretreatment was carried out under a reagent dosage of 0, 20, 50, 80 100%of acid consumption and at rest times of 7 and 15 days. The addition of sulfuric acid andsodium chloride results in the formation of hydrochloric acid in situ, which would benefit theconversion of refractory copper sulphides to soluble ores in acid media, thus generating afaster leaching.The leaching of the pretreated ore was carried out at concentrations of 0, 40 and 70 g/L deCl- at pH 1 for 4 hours at 300 RPM.The results show that the extractions are immediate since after 15 minutes of leaching theextractions remain constant, which would indicate an immediate dissolution of solublespecies in acid medium. By increasing the dosage of reagents up to 50% acidconsumption, the extractions increase, however, above these values the extractions arekept constant. The best condition was presented for 50% of the acid consumption at achloride concentration in the leaching solution of 70 g/L, the recoveries were about 41%.On the one hand the pretreatment times did not generate a significant increase in theextractions, on the other hand, carrying out the pretreatment under conditions of lowoxygen exposure generated a decrease in recovery of 10%.SEM analyzes were performed on mineral, pretreated ore and solid product of leaching.The analysis of the mineral determines that the morphology of the particles seems likeflakes, whereas the superficial chemical analysis shows a low presence of coppersulphides in the surface of the particles and the high presence of siliceous component(matrix). On the other hand, the pretreated mineral showed a porous morphology with highcohesion of fine particles, while the element mapping demonstrated the presence ofchalcopyrite transformation. Finally, the analysis of pretreated ore with low-aeration levelsin pretreated showed the presence of copper sulphides on the surface, and pretreated orewith high aeration the presence of copper was low. Both presented precipitation of salt atthe surface, ruling out some type of precipitation of some copper chloride. From the additional experiments, the results show the best extraction is obtained forleaching at 100 g/L with a previous chemical pretreatment of 50% acid consumption with arepose time of 7 days where the copper extractions were 41 %.Extractions close to 25% were obtained by pretreating the solid product of lixiviation undera 50% of acid consumption, while this same condition omitting the addition of saltgenerated a decrease of the recovery to 3%. Finally the lowest extraction, of 2%, wasreported for the experiment where the solid was leached at 70 g/L.Key words: EMELA, chemical pretreatment, pretreated ore, chloride.
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Keywords
CLORURO , EMELA , MINERAL PRETRATADO , PRETRATAMIENTO QUIMICO