To provide an apparatus for removing chlorine-based harmful gases, which sharply reduces the quantity of waste water generated in the course of treating the chlorine-based harmful gases in a secondary refining of aluminum.

In the apparatus for removing the chlorine-based harmful gases, wherein a cooling tower 2 and a dust collector 3 are connected to the latter stage of a melting furnace 1, and also wherein a cleaning tower 4 is connected to the latter stage of the dust collector 3, the above cooling tower 2 is of a spray dryer type on the one hand, a waste water recovery tank 8, which recovers the waste water which has been treated with chemicals, is installed at the latter stage of the cleaning tower 4 on the other hand. Cooling treatment is carried out in the cooling tower 2 by using the waste water which has been cleaned with chemicals by connecting the above waste water recovery tank 8 to the cooling tower 2.