Smelting reduction process with a coke packed bed for steelmaking dust recycling

A new smelting reduction process with a coke packed bed has been developed for iron, chromium, and nickel recovery from BOF dust, and for simultaneous recovery of zinc and iron from the electric are furnace dust. The process is characterized by direct use of fine raw materials without agglomeration, recovery of almost the whole amount of zinc and lead, and no emission of s econdary waste, compared with the conventional recovery methods. The commercial plant for BOF dust recycling has been operating stably with a metal production capacity of 200 tons per day. The blast condition is con trolled so that the temperature at the lower tuyere level becomes higher th an 1 550 degrees C, which is the condition required for the smelting reduct ion of chromium and iron oxides. The validity of the process idea for EAF dust recycling was confirmed and t he key technologies were established through the pilot plant tests with a s cale of 10 tons per day. It was found that zinc oxide was almost completely reduced and vaporized at the thermal state of the furnace, T(melt)greater than or equal to 1 550 degrees C, which allowed chromium and iron to be red uced. The control of the temperature and CO2/CO ratio of the top gas was im portant for the prevention of zinc adhesion on the wall of the furnace top.