Abstract: An apparatus for cleaning the exhaust gas of a high-pressure blast furnace comprises a coarse-particle separator, a prewasher and a differential-pressure annular gap washer traversed in succession by the gases. The exhaust gases can be passed through a main duct provided with an expansion turbine or through a bypass duct around the expansion turbine. The expansion turbine unit controls the back pressure at the blast furnace while a separate control circuit is provided to operate the differential-pressure washer with optimum efficiency. A quick-closing valve in the turbine-supply line and a quick-opening valve in the bypass line permits rapid switchover, a pressure-control valve in the bypass line maintains a constant backpressure at the blast furnace when the expansion turbine unit is shut down.