Analysis on Zn-rich waste tire treatment via co-combustion with coal: thermal property and migration/leaching of heavy metals

Abstract With the development of automobile industry technology, the production of waste tires (WTs) has been increasing rapidly, resulting in serious environmental damage and great treatment pressure. In this work, co-combustion of WT and coal under different mixing ratios were investigated to figure out the thermal property and heavy metals (HMs) migration in thermal treatment process. Besides, the chemical composition and leachability of ash samples were investigated. The results revealed that the addition of WT reduced the ignition temperature of the blend. Comprehensive combustion index (CCI) was higher than mono-combustion of coal and theoretical value with adding 20% WT, indicating there existed the synergistic effect between two fuels. Compared with coal ash, WT ash performed lower volatilization ratios of Zn, Cu, Ni and Cr. Furthermore, the volatilization of Cr/Ni decreased with the addition of WT. According to the comparison between theoretical and experimental values of Zn volatilization ratio, the Zn volatilization was promoted. However, there still had large amount of Zn fixed in ash to form minerals in co-combustion. In addition, leachability of both Zn and Cu and mixing ratio presented positive correlation. Leachability of both Cr and Ni in co-combustion ash were higher than that of mono-combustion ash.