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

摘要

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_2O_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_2O_3 ? SiO_2 might be the dominant mineral phase in ash. However, with the increase of CaO addition, the amount of 2CaO ? A1_2O_3 ? SiO_2 may decrease and the amount of 2CaO·SiO_2 and 3CaO·3Al_2O_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.