Abstract: This is a method of producing manufactured aggregates from coal combustion by-products having sulfur. Recycle fines containing calcium hydroxide, an aluminum-containing material, and water are mixed together to form a feed mix which is agglomerated into an agglomerated product. The agglomerated product is combined with curing fines which contain calcium oxide which together form a blended mix. The blended mix is cured using the moisture in the blended mix which is used to exothermally hydrate the calcium oxide in the blended mix to form calcium hydroxide and which autogenically provides the required heat for curing and converts the calcium oxide in the blended mix to a dry calcium hydroxide-containing material to form aggregate products and dry fines. The aggregate products are separated from the dry fines, the dry fines are recycled to the mixing step and the aggregates are taken and used as a useful product for other purposes.

Abstract: A process for making high-strength aggregates including hydrating calcium oxide containing coal combustion ash for a sufficient period of time to convert a high percentage of the calcium oxide to calcium hydroxide prior to forming the aggregates and curing the aggregates in high humidity. The moisture of the hydrated material is monitored to vary the hydration moisture to the desired set point. Further, the process involves producing high-strength aggregates from calcium hydroxide containing FGD ashes such as generated from duct sorbent injection and spray dryer processes.

Abstract: Flue gas is treated by a regenerable wet scrubbing process to reduce sulfur- and nitrogen oxides by reacting with a solution containing ammonium thiosulfate and hydroxide, and a ferrous chelating agent. A portion of the spent scrubber solution is regenerated by reaction with hydrogen sulfide, flashed to hydrolyze the polysulfide content, and then returned as regenerated solution to the principal scrubbing circuit.