INTRODUCTION

Mercury is one of the most toxic trace contaminant naturally occurring in the coals. During the coal combustion process at the coal-fired power plants mercury is released into the environment. To manage effectively the stack gas cleaning process, it is necessary to know the mercury content in the coal, and also in stack gas, liquid and solid wastes.

Standard methods of mercury determination in coal using atomic absorption spectrometry (ASTM D6414-14 and ISO 15237:2003) involve preliminary digestion of the sample that takes from 0.5 to 8 hours depending on the digestion conditions, followed by the quantitative measurement using Cold Vapor AAS.

Alternative methods for coal analysis (ASTM D6722-11 and EPA 7473) propose a simpler analysis procedure, namely, thermal decomposition of the sample combined with catalytic conversion, amalgamation and quantitative determination by AAS.

The use of an RA-915+/RA-915M mercury analyzer with a PYRO-915+ pyrolysis attachment provides fast direct determination of mercury in coal without digestion and intermediate amalgamation.

MEASURING METHOD

This method of mercury determination in coal is based on the atomization of mercury contained in the sample in a PYRO-915+ attachment and subsequent mercury determination by flameless AAS in a mercury analyzer RA-915M/RA-915+. The interference from the remaining impurity compounds is eliminated due to the high selectivity of the RA-915M/RA-915+ analyzer with the Zeeman background correction.