Investigation of changes in surface properties of bituminous coal during natural weathering processes by XPS and SEM

In this investigation, XPS and SEM were used to indicate the changes in surface properties of bituminous coal during natural weathering processes. Natural weathering processes of bituminous coal were conducted on the roof. XPS results showed that the content of CC and CH groups on bituminous coal surface decreased but the content of CO, CO, and OCO groups increased after natural weathering processes. Meanwhile, the contents of Al and Si elements on bituminous coal surface were also increased. SEM results showed that the surface roughness of bituminous coal was increased after natural weathering processes. Natural weathering processes not only changed surface chemical composition of bituminous coal but also changed surface topography of bituminous coal. In addition, natural weathering processes made bituminous coal surface more hydrophilic.