Disclosed herein is a method for reducing the amount of coarser particles from a stream of flue gas prior to treatment by a spray dryer absorption process (SDA). The method comprises the steps of directing a stream of flue gas containing entrained particles of varying sizes through a curve, thereby subjecting the particles to a centrifugal effect, collecting the particles predominately of the coarser size at a particles collecting means provided in the outer circumference of the curve, dispersing the flue gas reduced in particles of coarse particle sizes into the chamber of a spray dryer absorption apparatus, wherein the particles content of the original flue gas stream is above 20 g/Nm3. Also an apparatus for performing the method and a gas disperser is disclosed. The method substantially reduces the cost of the entire plant for treating flue gas having a high content of entrained coarse particles by eliminating the need for a particle pre-collector upstream the SDA.