of metakaolin having desirable strength enhancing properties when added to cement by virtue of the materials selected as additives to the coal the resulting ash byproduct can be designed to have a chemical structure that will enable it to act as a cementitious binder together with portland cement for strength enhancing properties of a cement or a concrete the particles being injected are in some cases much larger than the resulting ash particles indicating that the intense high temperature mixing causes particle reduction attrition both through intense collisions as well as through chemical combustion for example the particle size of the combustion product may be such that 90 percent of the particles may be less than 50 microns typically less than 20 microns while the particle size of 30 percent or more of the starting additive materials may be greater than 50 or 100 microns in addition to using the intense blending nature of the boiler plume for the combustion synthesis of unique ash products other beneficial additives can be mixed in the high temperature gas flow simply to achieve intimate mixing in a single processing step such additions of non reactive materials can be accomplished without reducing the efficiency of the coal combustion process in another embodiment geopolymer cements may be added in the combustion process to reduce pollutants in flue gas such geopolymer cements may serve as binding agents for mercury heavy metals nitrogen oxides and sulfur oxides and additional silica it is through the injection of these additions that the resultant fly ash formed in the coal combustion process may be modified by the inclusion of the chemical compounds within these additives directly into the coalescing fly ash in addition some chemical species added in this manner that.