Thermal behavior and kinetics of the pyrolysis of the coal used in the COREX process

Abstract

The pyrolysis characteristics of the coal used in the COREX process were investigated by thermogravimetric–mass spectrometric analytical technology. Firstly, thermal behavior of Xinglongzhuang coal and Datong coal was studied under an argon atmosphere at a heating rate of 20°C/min. Then, the effect of heating rate on pyrolysis of Xinglongzhuang coal was analyzed. In addition, the kinetics of the pyrolysis process was calculated for two coal samples. Results show that the pyrolysis process of the two coal samples has similar characteristics which could be divided into four stages, and the main pyrolysis temperature range of this coal type is from 300°C to 800°C. The heating rate mainly influences the primary pyrolysis stage of the coal, while the maximum weight loss rate and corresponding temperature change with increasing of heating rate. The evolved gas species vary as the heating rate increases, and the evolution of CO below 800°C is similar to that of CO2 which can be attributed to the decomposition of the same functional groups. The second order reaction and third order reaction can give a better representation of the main pyrolysis process with the apparent activation energy ranging from 100kJ/mol to 200kJ/mol.