Behaviour of coal ashes for pulverised coal injection at high temperatures in relation to their chemical and mineralogical composition - experimental and computational analysis

The selection of coals for pulverised coal injection usually consists of evaluating the carbonaceous matter. However, the reduction of permeability in the lower section of the blast furnace with high rates of pulverised coal injection can be associated with remaining ashes from the coal combustion process. The aim of this work is to evaluate the behaviour of coal ashes at high temperatures in relation to their chemical and mineralogical composition. These ashes were submitted to the following analysis: chemical (X-ray fluorescence), mineralogical (X-ray diffraction), fusibility (heating microscopy) and viscosity (rotational viscometer). The software FactSage was also used to evaluate the behaviour of coal ashes. It was observed that samples present different chemical and mineralogical compositions, reflecting in the fusibility and viscosity of ashes. Their proportions and relevant phases were determined by computational thermodynamics and also related to the experimental work.