Blast furnace operation - by reducing iron ore, limestone and coke in 3 different ttemp zones

摘要

Method comprises charging into the top of the blast furnace a burden comprising iron ore, sinter, pellets or other material with a metallic content, limestone or other fluxes and coke; passing the burden downwardly through a preliminary preheating and reducing zone in furnace of constantly increasing temp., constantly controlling the temp. of the zone by selectively introducing adjacent the lower end of the zone a flow of a heated gaseous carbonaceous reducing agent and blending the agent with the stream of heated gas moving up through the zone, bringing the now blended stream into intimate contact with burden and reacting gaseous agent and the burden to preheat and reduce the major portion of iron ore to form metallic iron and a gaseous prodt. and a first solids mixture of metallic iron, coke, slag and residual charge without causing a solution loss and without premature melting of the burden materials; passing first mixt. further downwardly through a second zone in furnace that comprises a bosh area, having in the lower portion thereof and adjacent the primary zone a consumable carbon grate constantly formed from coke in the first mixt., passing hot combustion gases from primary zone upwardly into secondary zone to form molten metal and slag; introducing into zone a heated carbonaceous reducing agent which combines with the hot combustion gases to reduce their temperature. and to assist in reducing additional iron oxide; passing molten materials downwardly through carbon grate into a primary zone that comprises a hearth area in which combustion occurs and which is maintained at a still higher temp. than secondary zone, injecting a mixt. of air and O2 as an oxidizing gas into primary zone and bringing gas into intimate contact with coke from the charge, the adiabatic flame temp. in zone being =1860 degrees C, forming CO2 by combustion and passing said hot combustion gases upwardly through the blast furnace; separately recovering molten metallic iron and molten slag; and withdrawing exhaust gases containing CO2 and H2O from the top of furnace.