Abstract: Hot dust laden gases from heated kilns in cement plants are mixed with a cooler moistening medium to provide a mixture having a dew point lying within a temperature range in which dust separation in electrofilters is greatly enhanced. Volatile alkali compounds in the gases condense on the dust particles and are substantially completely filtered out of the gases before discharge of the gases to the atmosphere. The electrical resistance of the dust in the gas is reduced by the moisture from high levels of about 10.sup.15 [ohm.times.cm] to levels below about 10.sup.11 [ohm.times.cm] so that efficient dust precipitation in electrofilters can be effected at low temperatures of about 150.degree. C. and at the same time removal of alkali from the cement clinker is enhanced.