Abstract: A low temperature carburizing method according to the present invention comprises: step (a) for pre-processing a metal to be processed; step (b) for inputting the metal to be processed to a reaction chamber and heating the same to a set temperature; step (c) for forming a vacuum atmosphere in the reaction chamber and introducing a reaction gas thereinto at a predetermined pressure to accelerate carburization; step (d) for supplying the reaction gas to the reaction chamber at a pressure equal to or lower than the pressure of the reaction gas of step (c) to spread carburization; and step (e) for repeating step (c) and step (d) at predetermined time intervals.

Abstract: A low temperature carburizing method according to the present invention comprises: step (a) for pre-processing a metal to be processed; step (b) for inputting the metal to be processed to a reaction chamber and heating the same to a set temperature; step (c) for forming a vacuum atmosphere in the reaction chamber and introducing a reaction gas thereinto at a predetermined pressure to accelerate carburization; step (d) for supplying the reaction gas to the reaction chamber at a pressure equal to or lower than the pressure of the reaction gas of step (c) to spread carburization; and step (e) for repeating step (c) and step (d) at predetermined time intervals.

Abstract: A two-stage fluidized bed reducing apparatus and a reducing method for fine iron ore of a wide particle size distribution with an increased degree of utilization of the reducing gas. Fine iron particles dropping through the holes of a gas distributor can be recycled into the fluidized bed furnace, thereby preventing an impediment of the reducing gas flow due to abnormal defluidizing or channeling. A first fluidized bed furnace dries, pre-heats and pre-reduces the fine iron ore, and a second fluidized bed furnace finally reduces the pre-reduced iron ore. Downstream of the respective fluidized beds are installed intermediate hoppers and gas/solid sealing valves. Thus, the fine iron ore particles which drop through the holes of gas distributors during the abnormal operation are recycled to the furnaces. Accordingly, the gas flow is not impeded.

Abstract: A two step twin-single fluidized bed type reduction apparatus for fine iron ore, and a method therefor, are disclosed. The fluidizing of the fine iron ore is stabilized so as to improve the reduction degree and the gas utilization rate, and so as to minimize the elutriation loss of the iron ore. The apparatus includes a first fluidized bed furnace for carrying out a first pre-reduction on only coarse/intermediate iron ore particles among fine iron ores of a wide particle size distribution by a bubbling/turbulent fluidization after their charge from a charging hopper, while making fine iron ore particles fly away. A second fluidized bed furnace carries out a first pre-reduction on the fine iron ore particles flown from the first fluidized bed furnace by a bubbling fluidization, and a third fluidized bed furnace carries out a second pre-reduction on the iron ores discharged from the first and second fluidized bed furnaces after their first pre-reduction.

Abstract: A 3-stage fluidized bed type iron ore reducing apparatus having X shaped circulating tubes is disclosed for forming a gas pore fluidizing layer of a fine iron ore, and for drying/pre-heating it to reduce it, so that the gas utilization rate and the reducing rate can be improved, as well as decreasing the gas consumption rate.