Factor     Hydrated Lime 
Mercury     Using hydrated lime DSI to control SO3 levels in flue gas allows
more effective removal of mercury by activated carbon.

Units using hydrate DSI may see good mercury removal without
activated carbon based upon coal type, unburned carbon in ash,
and particulate collection efficiency.
HF Many industrial applications use hydrated lime to control HF
emissions.
Arsenic Calcium added to coal can form calcium arsenate in the
furnace.  This eliminates arsenic poisoning of SCR catalyst.