Effect of acidic compositions on ash fusion temperatures

Ash fusion characteristic parameters of 129 typical original ash samples were collected locally and abroad, which included coals, sewage sludge and blends of sewage sludge/coal. These data were used to study the effect of acidic oxides including SiO₂, Al₂O₃, TiO₂ and P₂O₅ on ash fusion temperatures (AFTs). The refractory minerals such as quartz, metakaolin, mullite and rutile formed by SiO₂, Al₂O₃ and TiO₂ improve the AFTs. The results show that Al₂O₃ is a main factor in determining AFTs. Furthermore, the non-metal oxides P₂O₅ has a significant correlation with the FT of sewage sludge and sewage sludge/coal blends and its increase can obviously reduce AFTs, which might be caused by the higher P₂O₅ content in sewage sludge.