Characterization of the powder obtained from wasted tires reduced by pyrolysis and thermal shock process

R. Mis-Fernández¹; J.A. Azamar-Barrios², C.R. Ríos-Soberanis¹

¹ Centro de Investigación Científica de Yucatán, Unidad de Materiales Calle 43, No. 130, Colonia Chuburná de Hidalgo, C.P. 97200 Mérida, Yucatán, México

² Centro de Investigación y Estudios Avanzados (CINVESTAV) Unidad Mérida Km. 6 Antigua carretera a Progreso Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc., Méx.

ABSTRACT

This paper reports on the physicochemical characterization of solid powder obtained directly from wasted tires through pyrolysis and thermal shock process. Two different processes to reduce wasted tires were performed in order to acquire the residuals in powder to be characterized and compared. During this research, three phases were observed when pyrolysis was applied to rubber: the first one a solid black phase formed by organic and inorganic compounds such as zinc oxide (ZnO) and zinc sulphur (ZnS); secondly a gaseous phase containing hydrocarbons i.e. aromatic compounds and, finally, a liquid phase formed by heavy and light oils. By using X-ray diffraction technique, the relationship between temperature and the presence of inorganic compounds was determined varying the temperature of pyrolysis. In addition to X-ray diffraction, infrared spectroscopy, thermal analysis and scanning electron microscopy were used to fully characterize the samples. Comparing the results observed in both processes, it was found that thermal shock process presents some advantages over the pyrolytic, i.e. energy consume and solid black phase production; however, by pyrolytic degradation a powder richer in carbon compounds is obtained.

Keywords: Pyrolysis, thermal shock, characterization techniques.

RESUMEN

Este artículo se enfoca en la caracterización fisicoquímica del polvo sólido obtenido directamente de la reducción de llantas de desecho por medio de las técnicas de pirólisis y de choque térmico. Dos diferentes procesos para reducir las llantas usadas fueron realizados con el objeto de obtener los residuos en polvo para ser caracterizados y comparados. Durante esta investigación se observaron tres fases cuando la pirólisis era aplicada al hule: la primera, una fase sólida negra conformada por compuestos orgánicos e inorgánicos tales como el óxido de zinc (ZnO) y sulfuro de zinc (ZnS); en segundo lugar, una fase gaseosa conteniendo hidrocarbonos (compuestos aromáticos) y finalmente una fase líquida formada de aceites ligeros y pesados. Empleando la técnica de difracción de rayos X se determinó la relación entre la temperatura y la presencia de compuestos inorgánicos al variar la temperatura de pirólisis. Espectroscopía de infrarrojo, análisis térmicos y microscopía electrónica de barrido fueron utilizados adicionalmente para caracterizar las muestras. Comparando los resultados observados en ambos procesos, se encontró cierta ventaja de la reducción por choque térmico sobre el pirolítico; por ejemplo, el consumo de energía y la producción de fase sólida; sin embargo, la degradación pirolítica produce un residuo más rico en compuestos de carbono.

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