Abstract: A method of removing mercury from a coal fired power plant exhaust gas includes passing the exhaust gas through a bulk particle filter to remove coarse particles, introducing powdered activated carbon into the exhaust gas downstream of the bulk particle filter, introducing mercury laden powdered activated carbon containing exhaust gas into a fine particle filter to separate the mercury containing powdered activated carbon from the exhaust gas, separating the powdered activated carbon from the mercury at an elevated temperature in an inert gas environment and recirculating the separating powdered activated carbon into the exhaust gas upstream from the fine particle filter. The desorption is preferably effected at a temperature of about 300 to 500° C. for about 5 to 60 minutes. The method is adapted to remove mercury which may be on the order of about 1 to 1000 ppm to 1 to 10 micrograms/cubic meter of exhaust gas. Corresponding apparatus is provided.

Abstract: A method for reducing the carbon content of a combustion ash containing siliceous ash particles and carbon particles includes subjecting the combustion ash to comminution to reduce the particle size of the siliceous ash particles and the carbon particles followed by separating a portion of the carbon particles from the siliceous ash particles by subjecting the comminuted ash to a flow of gas which separates the carbon particles from the siliceous ash particles. The method preferably is performed in a unitary housing by employing autogenous grinding to effect the comminution of the particles and employing a classifying rotor to separate the comminuted portion of the carbon particles based on the density differential between the siliceous ash particles and the carbon particles. A method of making a concrete mixture employing the obtained combustion ash with reduced carbon content is also provided. An apparatus for reducing the carbon content of the combustion ash is also provided.

Abstract: A method and an apparatus for removing mercury from contaminated soils and industrial wastes are provided. The removed mercury may be recovered. A furnace vaporizes the mercury containing portion and the vapors are condensed. In one embodiment, an individual heating stage volatilizes water vapor and other volatile contaminants, such as hydrocarbons, with substantial vaporization of the mercury-containing portion, subsequently, a second temperature higher than the first is employed to vaporize the mercury containing portion. In one embodiment, a metallic salt reacts with sulfur in the material to form a stable solid sulfur compound to reduce sulfur content in the gaseous effluent. The addition of a metallic salt may also be employed to react with mercury halides to release elemental mercury therefrom. The contaminated material is thereby converted from one which is hazardous due to mercury contamination to one which is non-hazardous. The effluent is treated to reduce environmental hazards in the same.

Abstract: An electrostatic waste separation process for abrasive blasting residues containing an abrasive media and a hazardous material such as lead-based paint. A preconditioning stage as well as a postconditioning stage is used in addition to the electrostatic separation step. Preferably the preconditioning stage consists of the following steps: (a) a size classification step; (b) a ferromagnetic separation step; and (c) a gravity separation step. The concentrated hazardous material separated by this process can then be packaged in a container which can be safely transported, stored or disposed of. The nonhazardous blasting media may be recycled and reused or disposed of as a nonhazardous material.