Contribution of Minerals in Different Occurrence Forms to PM10 Emissions during the Combustion of Pulverized Zhundong Coal

Abstract

The comprehensive and quantitative assessment of the contribution of minerals with different occurrence forms to particulate matter with an aerodynamic diameter of less than 10 μm (PM10) emitted from the combustion of Zhundong coal is of great significance for its clean utilization and for the development of particulate matter formation mechanisms. Samples with simplified occurrence forms of inorganic species were prepared by water-, salt-, and acid-washing of Zhundong coal. The samples were combusted in a drop-tube furnace under 20 vol % oxygen at 1250 °C, and the emitted PM10 was collected. The effects of the minerals in different forms on the PM10 emissions were analyzed by comparing the mass concentration distributions, yields, and elemental compositions of PM10. The results showed that water-soluble, ion-exchangeable, acid-soluble, and acid-insoluble minerals contributed 8.3%, 37.8%, 29.7%, and 24.2% of the PM10 emissions, respectively. The distributions of the Na, Mg, Ca, and Fe contents in PM10 were bimodal, as follows: 63.6% of Na and 54.5% of Fe were deported to the ultrafine mode PM, while 63.6% of Mg and 86.6% of Ca were deported to the coarse mode PM. The distributions of the Si and Al contents were unimodal, namely: 92.9% of Si and 90.5% of Al were deported to the coarse mode PM. Water-soluble Na; ion-exchanged Mg, Ca, and Fe; and acid-insoluble Si and Al played decisive roles in the distribution of minerals in PM10.