Study on thermochemical kinetic characteristics and interaction during low temperature oxidation of blended coals

• Two interval stages were distinguished for both individual coals and blended coals.
• The synergistic interaction was observed during low temperature oxidation of blends.
• The apparent activation energy of stage 1 was smaller than stage 2.
• Third-order reaction mechanism model could be used to depict stage 1.
• Three-way transport diffusion mechanism model could be used to depict stage 2.

The low temperature oxidation characteristics of individual coals and blended coals were studied via thermogravimetric analysis. Blends 50% on dosage ratio were prepared to investigate their thermochemical behavior and kinetic. The low temperature oxidation process of coal could be roughly divided into two interval stages, corresponding temperature ranges of which were 30–140 °C and 150–260 °C, respectively. A synergistic interaction between blending coals was observed within the temperature range of 45–180 °C during the low temperature oxidation process. A certain addition of high volatile bituminous coal to the blended coals would help to relieve low temperature oxidation of coal, which could be attributed to the low moisture and some potential minerals that could increase the chemical inertness. Third-order reaction mechanism model and three-way transport diffusion mechanism model could be used to depict stage 1 and stage 2, respectively. And the apparent activation energy of stage 1 was smaller than stage 2.