Gas release characteristics during carbonization of iron coke hot briquette and influence of heating rate

The release characteristics of CH₄, H₂, CO and CO₂ from iron coke hot briquette (ICHB) during carbonization were studied. The results show that compared with briquette without iron ore, Fe₃O₄ can inhibit the release rate of H₂ and promote the production of CO and CO₂. In addition, when the heating rate increases from 3 to 7 °C/min, the release rates of CH₄ and H₂ increase, while the release rates of CO and CO₂ first increase and then decrease. The carbonization process of ICHB was segmented, and corresponding kinetic analysis was carried out. The results show that the activation energy of Stage II and Stage IV is higher in the carbonization process of ICHB, and the active pyrolysis of coal and the reduction of iron ore occur in these two stages. In addition, the effect of heating rate on the kinetic parameters of ICHB carbonization process was investigated. It was found that when the heating rate increased, the reaction activation energy of Stage IV decreased first and then increased, which was consistent with the release law of CO and CO₂. The analysis showed that the increase in heating rate leads to more reactions at higher temperatures, resulting in an increase in the release rate of some gases. In addition, thermal hysteresis can also cause some processes to fail to fully react at the end of heating. It is also found that the apparent activation energy and preexponential factor have kinetic compensation effect during the carbonization of ICHB.