Non-isothermal TG-DSC study on prediction of caking properties of vitrinite-rich concentrates of bituminous coals

- The stage of 300-900 °C showed intense devolatilization and endothermic reactions.
- No explicit correlations between rank and parameters of TG and DSC curves existed.
- A technique for predicting G based on the parameters of TG-DSC curves was proposed.

Vitrinite-rich concentrates were produced using a float-sink technique from five single-rank Chinese bituminous coals with Rrandom ranging from 0.88% to 1.73%. The non-isothermal thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of these concentrates were carried out simultaneously at the heating rate of 8 °C/min from 50 °C to 1200 °C, and the determination of the caking index (G) was also performed. The TGA results demonstrate that the devolatilization is divided into three regions and there are not explicit relationships between coal rank and characteristic parameters during the 300-900 °C region, such as DTGmax, Tmax, and weight loss. The DSC results show that the heat of pyrolysis is comprised of three stages characterized by different heat flows and no explicit correlations between coal rank and heat flow as well as peak number in the range of 300-900 °C exist. In terms of the TGA and DSC results, the relationship between the caking index and characteristic parameters derived from the TGA and DSC curves is examined and developed to predict the caking index of single-rank bituminous coal.