Coal tar pitch and molasses blended binder for production of formed coal briquettes from high volatile coal

- Thermal behaviors of coal briquettes in different temperature were analyzed.
- Ventilation drying with short time was applied to make high strength briquettes.
- Coal briquettes from high volatile coal were produced for COREX ironmaking process.

High volatile coal fines do not meet the requirements of various industrial production processes and cause large resource losses. Recycling coal fines by the production of formed coal briquettes has a great realistic significance in saving coal resources and protecting the environment. In order to utilize high volatile coal fines to produce coal briquettes as a substitute for COREX ironmaking process, thermal behaviors of coal, coal tar pitch and briquettes were analyzed. A blended binder composed of pitch and molasses was obtained and ventilation drying was applied to strengthen their bonding strength. Microstructure and composition of briquettes were tested by SEM and EDS. Results showed that both volatilization and carbonization of briquette should be processed in protecting atmosphere because of coal's low combustion temperature at 351 °C. The strengths of cured and carbonized briquettes are weaker than dried briquettes because of coal's violent volatilization which causes vast pores and loose structure in briquettes. Molasses can significantly improve the strength of dried briquettes. Ventilation drying with short time provides briquettes with higher strength than static drying. By adding 15% blended binders (pitch: molasses = 13:2), drop resistance of green briquettes reaches 19.4 times/2 m. After drying at 130 °C for 1 h with a gentle air flow of 1.2 m/s, drop resistance and compressive strength of dried briquettes are up to 56.6 times/2 m and 13.06 MPa, respectively. The briquettes consist of primarily C, a small amount of O and very small amounts of Al, Si, Ca, S and Fe. The strength and composition of briquettes favorably meet the requirement of COREX ironmaking process.