Investigation on improve ash fusion temperature (AFT) of low-AFT coal by biomass addition

The co-gasification of coal and biomass is of importance for coal clean conversion and biomass utilization on a large scale. To investigate the effecting behaviors of biomass on ash fusion characteristics of low ash-fusion-temperature (AFT) coal, the ash chemical properties of three materials (Shenmu coal (SM), chestnut shell (CS), and rice husk (RH)), the variations in SM mixed AFT with increasing CS or RH mass ratio and their mechanisms were explored through silicate-network structure theory, X-ray powder diffractometry, and FactSage software. The formations of anorthite, gehlenite and their eutectics caused SM with low AFT. An increased CS mass ratio led to the increasing contents of high melting-point (MP) kalsilite, lime and magnesia and the decreasing contents of low MP nepheline, olivine, and gehlenite, this made SM mixed AFTs increased gradually. Increasing high MP tridymite content led to SM mixed AFT mostly increased with increasing RH mass ratio. The temperature that all minerals changed into liquid phase based on FactSage calculation could reflect the AFT variation of samples.