Experiments and Modeling of Ash Mineral Evolution in Burning High-Sulfur Coal with Lime

Abstract

The mineral phase evolution of ash was studied when high-sulfur coal was burnt with CaO at different proportions. Experiments were carried out in a drop-tube furnace. Modeling via FACTSAGE was performed by obtaining the absent thermochemical property data of the key mineral 3CaO·3Al 2 O 3 · CaSO 4 and expanding the database. It was found that the ash mineral phases follow a certain rule to evolve and have an immense potential for modification. At low CaO proportion, 2CaO·Al 2 O 3 ·SiO 2 might be the dominant mineral phase in ash. However, with the increase of CaO addition, the amount of 2CaO·Al 2 O 3 · SiO 2 may decrease and the amount of 2CaO·SiO 2 and 3CaO·3Al 2 O 3 ·CaSO 4 may increase noticeably. Owing to the excellent hydraulic characteristics of the latter two minerals, coal ash is very possible to become cement-like. The findings may open up an efficient way to burn the high-sulfur coal. The burning of high-sulfur coal with lime may result in an attractive sulfur fixation as well as a high-quality byproduct.