PURPOSE: To perfectly remove secondary public nuisance substance in exhaust gas with inexpensive equipment and running cost without lowering the efficiency of a scrap preheating apparatus, by washing the exhaust gas of the scrap preheating apparatus after performing dust collection and succeeding dry cooling.

CONSTITUTION: The high temp. exhaust gas from an arc furnace 1 is guided to a scrap preheating apparatus 8 through ducts 4, 6 to preheat scrap 27. The preheated exhaust gas containing secondary public nuisance substances such as dust or org. substance adhered to the scrap is passed through a bag house 13 to collect dust while the dust removed gas is flowed into connection duct 14. The exhaust gas is cooled to 100°C or less by dry cooling utilizing temp. falling due to heat discharge in the bag house 13 and the connection duct 14. The org. substance or the like evaporated and gasified in the exhaust gas is condensed to be collected by a condensation tower 17. In addition, the water soluble org. substance with low b.p. remaining in the exhaust gas is absorbed and collected while washed in a washing tower 18 and clean gas is exhausted to the atmosphere.