Characteristics and kinetics of the pyrolysis of coking coal tailings

The influences of final temperature and heating rate on the pyrolysis characteristics of coking coal tailings and the pyrolysis products were examined by fixed-bed pyrolysis and TG analysis. The tailing pyrolysis kinetics parameters were calculated by using Coats-Redfern method. The activation energy of the pyrolysis of tailings was between 22.6-66.2 kJ/mol, and the process of pyrolysis could be described by three second-order reactions. The results of fixed reactor experiment showed that the temperature had important influence on the tailings volatiles release. There was no gas formation below 600 ℃, and the reaction remarkably occurred after 600 ℃, where the yields and the caloric value of gases increased simultaneously. With the increase of temperature, hydrogen, methane and carbon dioxide first increased and then decreased but carbon monoxide increased. The maximum release of hydrogen (72.61%) and methane(22.09%) appeared respectively at about 900 ℃ and 800 ℃. The tailings pyrolysis by 30 g tailings of coking coal could produce 4.3 L gas and 1.72 L hydrogen. The products had good yields and reuse value. The research is of great significance to guide the tailings disposal.