METHOD FOR REDUCING THE SOX EMISSION FROM A PLANT FOR MANUFACTURING CEMENT CLINKER AND SUCH PLANT

A description is given of a method as well as a plant for reducing the SOx emission from a plant for manufacturing cement clinker by which cement raw meal is preheated and burned in a plant comprising a cyclone preheater (1) a nd a kiln (7). The method is peculiar in that a catalyst in the form of a chloride compound and/or a mixture of several chloride compounds is introduc ed into the preheater (1) at its uppermost or next-to-uppermost cyclone stage ( 2, 3), that the catalyst is directed down through the preheater (1) to the kiln (7), that a partial amount of the kiln exhaust gas stream containing the catalyst in vaporized form is extracted from the kiln (7), that the extracte d exhaust gas stream is cooled off so that the catalyst is present in solid form, that solid matter is separated from the cooled exhaust gas stream and that at least some of the separated solid matter containing the catalyst is recirculated for renewed introduction into the preheater (1).Hereby is obtained an effective reduction of the SO2 emission. The reason for this is that chloride compounds and/or a mixture of several chloride compounds will promote the reaction catalytically of SO2 with CaO for formation of CaSO3 an d it will further promote the reaction of SO2 with CaCO3 for formation of CaSO 3 and CO2. Since CaCO3 is present in great abundance, the SO2 reduction may be effected without any use of extraneous chemicals.