Abstract: In a cast house of a blast furnace, one or more movable exhaust hoods, connected to exhaust ducts, are provided for extraction of gas and dust. In order to provide such a hood which is easily moved manually by the operating personnel but which, with its duct, nevertheless does not unduly obstruct the working space, the hood is carried by a swivellable duct section which is connected to a fixed duct section at its swivelling axis and is supported, in cantilever fashion, by a bearing, e.g. a ball bearing, which is located outside the duct and extends circumferentially around the duct.