Process for treating coal to reduce sulfur content in flue gases produced by coal combustion

Claim 1

A process for reducing the gaseous sulfur oxide content of flue gases comprising the steps of: burning in a combustion zone coal containing weakly bound cations of one of the alkali metal and alkaline earth metals or conbinations thereof in ion exchangeable form thereby producing flue gases, the burning of such coal in the combustion zone causing a substantial portion of the sulfur dioxide in the coal to be converted to sulfates in a residue in the combustion zone thereby reducing the amount of gaseous sulfur dioxide in the flue gases produced in the combustion zone; recovering the sulfate containing residue from the combustion zone; contacting at least a portion of the flue gases with coal containing weakly bound cations of one of the alkali metal and alkaline earth metals or combinations thereof in ion exchangeable form in a scrubbing zone to sorb a portion of the sulfur dioxide in the contacted flue gases on the coal, in the presence of water to maintain, during such contacting, a relatively high moisture content, the moisture content in the coal being from at least about 5% to about 60% by weight; and combusting in the combustion zone the coal contacted by the flue gases in the scrubbing zone.