Technique and estimation of using reducing gas from iron ore-coal briquette to produce direct reduced iron

Recycling reducing gas was heated to 1 100℃ with blast furnace gas, fuel gas from garbage power, low caloric value gas or with heat from hot coke, hot direct reduced iron (DRI), or other heat in a hot-blast stove. Then, the recycling reducing gas was input to a reductive shaft kiln to heat iron ore-coal briquette to produce DRI. Sulfur and CO₂ were recovered from the top gas, and the purified gas was used as the recycling reducing gas. The carbocoal and coke from coal carbonization in the briquette acted as skeleton, which was different from coke in the blast furnace. The coal consumption of DRI was reduced through using the afterheat of reducing gas to preheat and carbonize briquette, using the high surface area of iron concentrate and coal powder, and using coal carbonization and gasification to accelerate carbon gasification reaction and direct reduction reaction at low temperatures. If the temperature of the top gas drops to 150℃, 218 kg coal is blended, and blast furnace gas of about 947 m³ is consumed, the energy consumption will be about 333 kg/t coal. Compared with the blast furnace process, this process can economize 52% energy and reduce about 83% CO₂ emission;it will save about 84 kg standard coal than MIDREX process. This technical process is abbreviated to DRI-NHQ.