Process for producing cement from a flue gas desulfurization process waste product
AssigneeDravo Lime Company
InventorsManyam Babu, John W. College, Russell C. Forsythe
Life of this patent
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Abstract
Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite 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 released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock.
Claims16
A process for producing cement 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
- pulverizing said cement clinker to produce cement.
A process for producing cement 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 sulfur dioxide;
- removing said cement clinker from the rotary kiln and pulverizing the same to produce cement;
- discharging said sulfur dioxide from the rotary kiln;
- passing said discharged sulfur dioxide to an indirect heat exchanger to heat air;
- and
- using the heated air so produced to remove water from said moist mixture during said agglomerating.
A process for producing cement 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 resulting from a flue gas desulfurization process using a magnesium-enhanced lime slurry for reaction with sulfur dioxide in a gas stream;
- 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 sulfur dioxide;
- discharging said sulfur dioxide from the rotary kiln to an indirect heat exchanger and heating air in said heat exchanger therewith;
- using said heated air to remove water from said moist mixture during agglomeration;
- and
- pulverizing said cement clinker to produce cement.
Dependencies are inferred from the claim text.