Abstract: A method of treating a fossil fuel for combustion, which includes heating the fossil fuel and an additive in a combustion zone. The additive contains a lime flux that lowers the melting point of lime sufficiently so that lime in the combustion zone melts wholly or partially. The additive reacts with the fossil fuel char and its sulphur plus ash components, in the combustion zone to achieve the following results alone or in combination: accelerated combustion, desulphurization, nitrogen oxides emission reduction, pozzolanic or cementitious product production or combustor anti-fouling.