FACTSAGE™ thermo-equilibrium simulations of mineral transformations in coal combustion ash

Abstract

The aim of this investigation is to report on the influence of operating conditions, and of additives such as potassium carbonate, on the slagging behaviour of South African coal. This was done using a FACTSAGE™ model that was previously developed to simulate the chemistry and mineral transformations occurring during a fixed-bed countercurrent gasification process. The mineral transformations in K- and Al-containing inorganic compounds under certain thermal conditions were tracked to see whether these species remain in the minerals or are captured by the slag. The main contributors to slag formation and possible inorganic mineral transformations were identified. The addition of potassium carbonate to the coal before thermal processing decreases the melt formation temperature and the melt percentage. The mineral transformations and slagging behaviour depend on the percentage of potassium in the sample, as well as the basic components present in the coal