A METHOD FOR THE REMOVAL OF MERCURY FROM A STREAM OF FLUE GAS OBTAINED FROM THE COMBUSTION OF COAL, AND A COMPOSITION COMPRISING SPENT SORBENT.

摘要

A method for the removal of mercury from a stream of flue gas obtained from the combustion of at least one coal type having an ASTM D388 coal rank of 3 includes the steps of introducing a kaolin or metakaolin-containing sorbent into the stream of flue gas and contacting the mercury with the kaolin or metakaolin-containing sorbent at a point where both the kaolin or metakaolin-containing sorbent and active free silica are present in the stream. The temperature of the flue gas is at least 900° C. The active free silica content of the flue gas resulting from the combustion of the coal is supplemented by the introduction of added active free silica such that the weight percentage of the total amount of active free silica relative to the weight of kaolin or metakaolin is at least 10%, the weight of any kaolin being expressed as the weight of metakaolin.