At least one steel company utilizes organic waste liquids as a heat and carbon content source to partially replace the coke that is used to charge the blast furnaces. The waste liquids fed to the blast furnace are likely to contain hazardous constituents. Temperature and residence time in the blast furnace favor total destruction of the principal organic hazardous constituents (POHCs) of the waste fuel but verification of destruction efficiencies has not been attempted up to now. Also, reduction reactions that occur in a blast furnace may promote the formation of products of incomplete combustion (PICs). Tests were conducted while feeding waste fuel to a blast furnace located at a major steel mill. The primary objective of the test program was to determine the fate of the POHCs of the waste fuel and to look for formation of PICs, notably dioxins and dibenzofurans.