Tostación de MoS2 con CaO sin producción de SO2.
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Date
2025
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Publisher
Universidad de Concepción
Abstract
En esta memoria, se estudió la factibilidad técnica de la tostación de MoS2 en presencia de CaO para producir compuestos de molibdeno solubles, como una nueva alternativa.
Se realizaron experimentos usando mezclas de MoS2 con CaO variando la razón molar de mezclas en proporciones de MoS2: CaO, 1:2,1:2,67, y 1:3, la temperatura de trabajo en el rango de 700 °C hasta 1150 °C, y el tiempo de operación de los experimentos que se ajustó desde 10 hasta 145 minutos. La caracterización para identificar las fases presentes en los reactivos y productos, se emplearon análisis de difracción de rayos X (DRX), la conversión de la reacción se determinó por análisis químicos mediante disolución de los productos y absorción atómica.
La temperatura fue uno de los factores más influyentes en la reacción de tostación. Durante la tostación en ambiente inerte, a 900°C, los análisis de DRX mostraron que las calcinas reaccionaron casi por completo, siendo sus fases principales Mo, CaMoO4 y CaS. En cambio, en el rango de 700°C a 800°C, aún se observaron las fases iniciales de MoS2 y CaO. Sin embargo, a temperaturas superiores a 900°C, además de CaMoO4 se observó trióxido de molibdeno.
En temperaturas entre 700°C y 900°C, a 900 °C, y tiempo de tostación de 120 minutos y razón molar MoS2:CaO de 1:3, se observó mayor conversión de molibdenita.
La razón molar resultó ser un factor crítico en las operaciones de tostación. En experimentos con una razón MoS2:CaO de 1:2,67, los productos de tostación fueron solamente CaMoO4 y CaS. En cambio, al trabajar con un exceso de CaO (razón de 1:3), se identificó la fase de molibdeno metálico.
El CaO demostró ser un desulfurante eficaz, ya que permitió fijar el azufre como un compuesto sólido (CaS) reduciendo el riesgo de formación de gases tóxicos SO2(g). Se encontró que la producción de molibdeno y molibdato de calcio ocurre según la reacción: 3 MoS2 + 8 CaO → Mo + 2 CaMoO4 + 6 CaS
The feasibility of roasting MoS2 in the presence of CaO was studied in an inert atmosphere to produce soluble molybdenum compounds as a novel alternative processing route. Experiments were conducted varying the molar ratio of the MoS2:CaO mixture (1:2, 1:2,67 and 1:3), the operating temperature (ranging from 700 °C to 1150 °C), and the roasting time (from 10 to 145 minutes). The phases present in the raw materials and final products were characterized using X-ray diffraction (XRD). The extent of conversion was determined through chemical analysis by dissolving the products and quantifying molybdenum via atomic absorption spectroscopy. Temperature was one of the most influential factors in the roasting process. Under inert atmosphere at 900 °C, XRD analysis revealed that the calcines reacted almost completely, with the main phases being metallic Mo, CaMoO4, and CaS. In contrast, at 700-800 °C, unreacted MoS2 and CaO were still observed. However, at temperatures above 900 °C, molybdenum trioxide (MoO3) was also detected alongside CaMoO4. At temperatures between 700 °C and 900 °C, the highest conversion of molybdenite was observed at 900 °C with a roasting time of 120 minutes and a molar ratio of MoS2:CaO of 1:3. The molar ratio was identified as a critical factor in the roasting behavior. In experiments with a MoS2:CaO ratio of 1:2,67, only 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑂 4 and CaS were observed in the roasted products. In contrast, when using an excess of CaO (1:3 ratio), the presence of metallic molybdenum was detected. CaO proved to be an effective desulfurizing agent, as it enabled sulfur to be fixed in solid form as CaS, thereby minimizing the risk of toxic SO2(𝑔𝑔) gas formation. The formation of molybdenum metal and calcium molybdate followed the reaction: 3 MoS2 + 8 CaO → Mo + 2 CaMoO4 + 6 CaS
The feasibility of roasting MoS2 in the presence of CaO was studied in an inert atmosphere to produce soluble molybdenum compounds as a novel alternative processing route. Experiments were conducted varying the molar ratio of the MoS2:CaO mixture (1:2, 1:2,67 and 1:3), the operating temperature (ranging from 700 °C to 1150 °C), and the roasting time (from 10 to 145 minutes). The phases present in the raw materials and final products were characterized using X-ray diffraction (XRD). The extent of conversion was determined through chemical analysis by dissolving the products and quantifying molybdenum via atomic absorption spectroscopy. Temperature was one of the most influential factors in the roasting process. Under inert atmosphere at 900 °C, XRD analysis revealed that the calcines reacted almost completely, with the main phases being metallic Mo, CaMoO4, and CaS. In contrast, at 700-800 °C, unreacted MoS2 and CaO were still observed. However, at temperatures above 900 °C, molybdenum trioxide (MoO3) was also detected alongside CaMoO4. At temperatures between 700 °C and 900 °C, the highest conversion of molybdenite was observed at 900 °C with a roasting time of 120 minutes and a molar ratio of MoS2:CaO of 1:3. The molar ratio was identified as a critical factor in the roasting behavior. In experiments with a MoS2:CaO ratio of 1:2,67, only 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑂 4 and CaS were observed in the roasted products. In contrast, when using an excess of CaO (1:3 ratio), the presence of metallic molybdenum was detected. CaO proved to be an effective desulfurizing agent, as it enabled sulfur to be fixed in solid form as CaS, thereby minimizing the risk of toxic SO2(𝑔𝑔) gas formation. The formation of molybdenum metal and calcium molybdate followed the reaction: 3 MoS2 + 8 CaO → Mo + 2 CaMoO4 + 6 CaS
Description
Tesis presentada para optar al Título de Ingeniero/a Civil Metalúrgico/a.
Keywords
Molibdeno, Tostación (Metalurgia), Termodinámica