Patent ID: 7789944

Claim:
A system for treating gas extracted from cement kiln comprising: a probe for extracting a part of combustion gas, while cooling it, from a kiln exhaust gas passage, which runs from an inlet end of a cement kiln to a bottom cyclone; a classifier for separating coarse powder from dust contained in the combustion gas extracted by said probe; a wet dust collector for collecting dust of the extracted gas containing fine powder discharged from said classifier, said wet dust collector having a wet scrubber, a circulation liquid tank to which slurry containing dust which is collected by said wet scrubber is fed, and a pump for returning a part of said slurry in the circulation liquid tank to the wet scrubber; a device for feeding a sulfurizing agent for sulfurizing lead contained in the kiln exhaust gas to an entrance side of said wet scrubber; and a flotation facility for separating lead from said slurry obtained by the wet dust collection.