TITLE:
Temperature Fractionation (TF) of Hg Compounds in Gypsum from Wet Flue Gas Desulfurization System of the Coal Fired Thermal Power Plant (TPP)
AUTHORS:
Matej Sedlar, Majda Pavlin, Radojko Jaćimović, Andrej Stergaršek, Peter Frkal, Milena Horvat
KEYWORDS:
Temperature Fractionation, Mercury Compounds, FGD Gypsum, Multi-Element Analysis, Spiking
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.6 No.12,
November
18,
2015
ABSTRACT: Gypsum from the wet
flue gas desulfurization system of the lignite fired thermal power plant Sostanj, Slovenia, can efficiently retain mercury (Hg), of which most is
contained in finer gypsum fractions, with concentrations above 10 kg-1.
The aim of this work was to identify and study the temperature stability of Hg
species in gypsum by a temperature fractionation (TF) method. A self-constructed
apparatus was used that consisted of an electrical furnace for controlled
heating up to 700°C, with a heating rate of 2.2°C·min-1, and an AAS detector
with Zeeman background correction. The pattern of Hg release during temperature
increase depends highly on the matrix/substrate in which it is contained. Based
on spiking gypsum with known Hg compounds we concluded that the largest
proportion of Hg in gypsum belongs to Hg-Cl and Hg-Br compounds appearing at
160°C to 200°C, followed by smaller amounts of HgO, HgS and Hg sulfates
appearing at 300°C and 450°C. Further development of methodology for
identifying Hg species would require identification of the decomposition
fragments of Hg and other compounds, complemented by a better understanding of
Hg reactivity at higher temperatures.