Characteristics and catalytic actions of inorganic constituents from entrained-flow coal gasification slag

The morphology, mineralogy, and elemental distribution of inorganic constituents from two entrained-flow coal gasification slags were mainly investigated to understand the physico-chemical characteristics of the two slags. The fully molten and partly molten inorganic components in the coarse slag tend mainly to co-exist in the overlapping bulk of lumps and agglomerates, whereas the two ones in the fine slag almost tended to be discretely presented in spherical particles and agglomerates, respectively. The trace elements (Pb, As and Zn) with great volatile behaviors were easily concentrated into the fine slag. Summarily, the inorganic constituents in gasification slags predominantly contained crystalline components (silicates, aluminosilicates, and Ca–Fe and Fe oxides) and vitreous components (Ca–Fe-aluminosilicate glass). Simultaneously, a rough distribution model for main ash-forming elements in gasification slags was proposed. Also, the catalytic actions of inorganic constituents in the two gasification slags were assessed using a thermo-gravimetric analyzer. It was found that the inorganic constituents in gasification slags can take a distinct catalytic action on the carbon gasification, mainly due to the predominant presence of these catalytic components (Ca–Fe and Fe oxides). A higher gasification reactivity of the coarse slag was mainly ascribed to a higher content of its catalytic components, compared to the fine slag.