Method for the removal of mercury from a stream of flue gas obtained from the combustion of coal

A method for the removal of mercury from a stream of flue gas obtained from combustion of at least one coal type having an ASTM D388 coal rank of <3, the method comprising the steps of:

• introducing a metakaolin-containing sorbent into the stream of flue gas for removing the mercury from the stream of flue gas;
• contacting the mercury with said metakaolin-containing sorbent at a point where an active free silica and said metakaolin-containing sorbent is present in the stream of flue gas and a temperature of the stream of flue gas is at least approximately 900° C., wherein said active free silica content of the flue gas results from the combustion of the at least one coal type;
• supplementing said active free silica from the combustion of the at least one coal type with an added active free silica such that a weight percentage of a total amount of active free silica relative to a weight of metakaolin-containing sorbent is at least approximately 10%.