Mercury release from FGD

The release of mercury from flue gas desulfurization (FGD) gypsum in the manufacture of 100% FGD wallboard was studied. Calcination, with product temperatures ranging from 150 to 180 °C, appears to be the most likely process to release mercury from the FGD. Two samples evaluated in trials conducted to simulate the calcining of FGD in flash calcining and kettle processes showed that the potential of mercury release exists. The differing amounts of mercury released by the two processes could be separated by orders of magnitude. Measurements in real production facilities are essential to developing a valid answer to the question of mercury release during FGD gypsum wallboard production.