Process for producing cement and elemental sulfur from a flue gas desulfurization waste product
AssigneeDravo Lime Company
InventorJohn W. College
Life of this patent
Estimating the term…
Abstract
Cement and elemental sulfur are produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfate hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide produced during the calcination is cooled and contacted with hydrogen and carbon monoxide to reduce the same to elemental sulfur.
Claims11
A process for producing cement and elemental sulfur from a flue gas desulfurization process waste product, comprising:
- providing a moist flue gas desulfurization process waste product containing 80-95 percent by weight of solids of calcium sulfite hemihydrate and 5-20 percent by weight of solids of calcium sulfate hemihydrate;
- adding a source of aluminum, iron, carbon, and a siliceous material to said flue gas desulfurization process waste product to form a moist mixture thereof;
- agglomerating said moist mixture while removing water therefrom, by contact with hot air, to provide a dry agglomerated kiln feedstock containing about 6 percent or less water;
- calcining said dry agglomerated kiln feedstock in a rotary kiln to produce a cement clinker and a sulfur dioxide-containing gas;
- discharging said sulfur dioxide-containing gas from said rotary kiln into an indirect heat exchanger to cool said gas;
- contacting the resultant cooled sulfur dioxide-containing gas with hydrogen and carbon monoxide in the presence of a reducing catalyst sufficient to form elemental sulfur;
- separating said elemental sulfur therefrom.
A process for producing cement and elemental sulfur from a flue gas desulfurization process waste product, comprising:
- providing a moist flue gas desulfurization process waste product containing 80-95 percent by weight of solids of calcium sulfite hemihydrate and 5-20 percent by weight of solids of calcium sulfate hemihydrate;
- adding fly ash containing aluminum and iron, carbon, and sand to said flue gas desulfurization process waste product to form a moist mixture thereof;
- agglomerating said moist mixture while removing water therefrom, by contact with hot air, to provide a dry agglomerated kiln feedstock containing about 6 percent or less water;
- calcining said dry agglomerated kiln feedstock in a rotary kiln to produce a cement clinker and a sulfur dioxide-containing gas;
- discharging said sulfur dioxide-containing gas from said rotary kiln into an indirect heat exchanger to cool said gas and heat air;
- passing said heated air to said agglomerating step to remove water from further said moist mixture during agglomeration;
- contacting the resultant cooled sulfur dioxide-containing gas with hydrogen and carbon monoxide in the presence of a reducing catalyst sufficient to form elemental sulfur;
- separating said elemental sulfur therefrom.
Dependencies are inferred from the claim text.