Effect of Ca/Fe on the melting characteristics of high ash-fusion-temperature anthracite coal ash

Coal gasification is still one of the main ways of utilizing coal resources. However, slagging is inevitable in the gasification process, and one of the main reasons is that the coal ash melting temperature is too high, so there is an urgent need to improve the ash fusibility of high ash melting point coals. A Jincheng anthracite (WY) was chosen as raw coal, and the impact of adding calcium and iron on the ash melting characteristics of anthracite coal was investigated using an ash melting tester, combined with FactSage thermodynamic calculations. The results indicate that the addition of Ca, Fe, and Ca-Fe composite additives can all reduce the ash fusion temperatures (AFTs) of the WY coal, with the melting aid effect of Fe being more significant than Ca. According to thermodynamic calculations, the liquid phase comprises of 89.90% at 1500 degrees C. The WY coal ash flow temperature (FT) exceeding 1500 degrees C is attributed to the presence of the refractory mineral mullite. Furthermore, the presence of low-temperature eutectic calcium feldspar and iron spinel will reduce the coal ash fusion temperature, particularly the presence of iron spinel, which significantly decreases the ash fusion temperature.