Mercury emissions from coal combustion.

Mercury liberated during coal combustion can be either discharged as vapor in the flue as or retained in the furnace ash. About 90 percent (by weight) of the mercury released from a furnace fired with pulverized coal appears to be in the vapor phase, and 10 percent remains with the furnace residual ash. For a 700-megawatt unit, approximately 2.5 kilograms of mercury per day are released.