Study on preparation mechanism and thermal conversion behavior of high thermal strength briquette

To efficiently utilize the growing pulverized coal resources in the Xinjiang Region, the simplest and most effective solution is to prepare briquette. The quality of briquette can be assessed by its cold compressive strength and thermal strength. This paper selects asphalt pitch as the binder and proposes a method of thermal pretreatment to enhance the thermal strength of briquette. It explores the effect and mechanism of key process parameters on improving thermal strength and calculates the combustion kinetics parameters of the briquette product. The results show that the cold compressive strength of briquette with asphalt pitch binder is 10.9 MPa, and its thermal strength is 0 MPa. After thermal pretreatment at 250 ℃, the cold compressive strength is 9.8 MPa, and the thermal strength is 21.5 MPa. After thermal pretreatment at 450 ℃, the cold compressive strength is 8.5 MPa, and the thermal strength is 35.3 MPa. The thermal pretreatment process enhances the solid bridge bonding between particles in the briquette. At 250 ℃, the softening and melting dispersion of the asphalt pitch followed by cooling forms solid bridges, increasing the thermal strength through physical changes. At 450 ℃, chemical reactions occur within the briquette due to thermal pretreatment, forming stable macromolecular structures upon completion of the reaction at the contact surface, thereby increasing the thermal strength. Different mechanistic functions are used to calculate the activation energy, pre-exponential factor, and correlation coefficient of the briquette, and the comparison of correlation coefficients shows that the combustion of the briquette product follows second-order reaction kinetics. The research provides support for the preparation of high thermal strength briquette and the refinement of mechanisms to enhance its thermal strength.