Investigation of Slagging-Fouling and Mineral Contents in Low-Rank Coals for Improved Combustion Performance

Despite the problems associated with low-rank coal, this type of coal is still widely used in various applications including the power generation sector. In this study, three low-rank coals (LRC) with high mineral content of SiO₂, Al₂O₃, and MgO were selected and comprehensively investigated. Investigations include ash fusion temperature (AFT), theoretical calculation, combustion experiment with drop tube furnace (DTF), and ash analysis using scanning electron microscope (SEM) and x-ray diffraction (XRD). The investigation revealed that T-Coal with high SiO₂ and P-Coal with high Al₂O₃ mineral produce ash deposition which did not adhere on the probe surface of either slagging or fouling area. T-Coal ash consists of fine and solid particles, but the presence of the dominant albite mineral, 29.09% in slagging probe and 28.71% in fouling probe, may have a negative impact on ash deposition. P-Coal ash is dominated by fine particles with a predominance of quartz and other high-melting minerals. A-Coal with high MgO mineral has good results in slagging aspects. However, the high Fe₂O₃ on A-Coal results in low ash fusion and produces more hematite mineral (17.70%) in the fouling probe. This study shows that several types of LRC have good evaluation on ash-related problems which potentially can be used as coal blending for further utilization in power generation.