Abstract: A method for treating powdered activated carbon (PAC) and/or coal combustion residues (CCRs) by heating at least one of a spent PAC and/or a CCR to separate at least one heavy metal from the at least one of the spent PAC and/or the CCR to create a clean stream and a heavy metal stream, combining the heavy metal stream with a water soluble alkaline-earth metal sulfide to create a combined stream, and removing at least a portion of the at least one heavy metal from the combined stream. The heating may further include heating the at least one of the spent PAC and/or the CCR in an inert atmosphere. Further, the combining may include combining the heavy metal stream with the water soluble alkaline-earth metal sulfide and a catalyst and/or a surfactant or hyperdispersant.

Abstract: A method for reducing pollution in a cement kiln environment and a system for treating cement kiln exhaust gas are provided. The method includes the steps of: treating a cement kiln exhaust gas stream with a treating fluid, such as a water soluble alkaline-earth metal sulfide. In one application, the treating fluid is injected by spraying droplets into the cement kiln exhaust gas stream. A system for treating cement kiln exhaust gas includes a reagent containing a water soluble alkaline-earth metal sulfide in water, and a nozzle to spray the reagent into the cement kiln exhaust gas stream.

Abstract: A system and method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Abstract: A method for treating cement kiln exhaust is provided. The method includes the steps of: providing a cement kiln exhaust gas stream from a kiln; providing a water soluble alkaline-earth metal polysulfide; combining the cement kiln exhaust stream with the water soluble alkaline-earth metal polysulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Abstract: A method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Abstract: A method for treating powdered activated carbon (PAC) and/or coal combustion residues (CCRs) by heating at least one of a spent PAC and/or a CCR to separate at least one heavy metal from the at least one of the spent PAC and/or the CCR to create a clean stream and a heavy metal stream, combining the heavy metal stream with a water soluble alkaline-earth metal sulfide to create a combined stream, and removing at least a portion of the at least one heavy metal from the combined stream. The heating may further include heating the at least one of the spent PAC and/or the CCR in an inert atmosphere. Further, the combining may include combining the heavy metal stream with the water soluble alkaline-earth metal sulfide and a catalyst and/or a surfactant or hyperdispersant.

Abstract: A method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Abstract: A method for treating cement kiln exhaust is provided. The method includes the steps of: providing a cement kiln exhaust gas stream from a kiln; providing a water soluble alkaline-earth metal polysulfide; combining the cement kiln exhaust stream with the water soluble alkaline-earth metal polysulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

Abstract: A method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.