PIXE analysis of the hydrothermal leaching of trace elements in coal

The miner and trace element content in coal is of great interest due to the potential impact on the environment from the release of these elements during combustion, Reducing the concentrations of potentially hazardous elements in coal prior to combustion is one way of dealing with this issue. In this research, particle induced X-ray emission (PIXE) was used to investigate a hydrothermal leaching process for the removal of trace elements from a bituminous coal. The leaching agents HNO3 and NaOH were evaluated along with the effects of process parameters (temperature, pressure, and time) on the method's effectiveness. The variable with the greatest influence was the leaching agent itself. HNO3 was determined to be more effective than NaOH in reducing elemental concentrations for nearly all the elements determined. Increasing the temperature did result in greater reductions for some elements (Cl, Br, Zn) whereas increasing the pressure and duration of the leaching process had minimal impact on reductions in elemental concentrations.