Abstract: Apparatus is described that is particularly adapted for suppressing fume generated in the flow of molten metal through the runner system of a blast furnace cast house. Burners adapted for combusting fuel and air are disposed at longitudinally spaced locations along the runner system. Fuel and air in predetermined amounts are discharged from the burners to create flame and disperse it along the axis of the runners. The flame operates to consume ambient air in the combustion process thereby to starve the region over the metal streams of oxygen that would otherwise combine with metal vapors to create fume-producing metallic oxides.