| CPC C21B 3/02 (2013.01) [C21B 13/0013 (2013.01); C21B 13/004 (2013.01); C21C 1/06 (2013.01)] | 5 Claims |
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1. A method for iron making by continuous smelting reduction, comprising the following steps:
(1) uniformly mixing iron-containing mineral powder with a reducing agent and a slag former to obtain mixed powder materials, and placing the mixed powder materials in a continuous feeding system which is a device capable of metering conveyed materials, and selecting a screw feeder or a feeding bin with a metering pump, wherein the iron-containing mineral powder is iron ore powder, or iron-containing tailing powder or iron-containing smelt slag with a mass percentage of full iron grade greater than or equal to 30%, the reducing agent is pulverized coal, the slag former is lime; in the mixed powder materials, the quantity of the reducing agent added is 1.1-1.3 times of a total quantity of C required for a complete reaction of Fe in the iron-containing mineral powder and C in the reducing agent; the quantity of the slag former is determined so that alkalinity of the mixed powder materials is 2-3, and reaction formulas of the complete reaction are:
FexOy+yC=yCO+xFe,
FexOy+yCO=yCO2+xFe, and
FexOy+(y/2)C=(y/2)CO2+xFe;
(2) placing furnace startup materials in a reducing furnace, wherein a seal cover is assembled at a top of the reducing furnace, a stirring device is arranged at the top of the reducing furnace, the stirring device and a lifting device outside the reducing furnace are assembled together, a shaft rod of the stirring device penetrates through the seal cover to be inserted in the reducing furnace, a stirring paddle is assembled at a bottom end of the shaft rod, an air inlet channel and an air exhaust opening are also formed in the seal cover, a feed pipe penetrates through the seal cover to be inserted in the reducing furnace, a molten slag overflow opening is formed in an upper part of a side wall of the reducing furnace, an iron notch is formed in a bottom of the reducing furnace and communicates with a siphon pipeline, and the siphon pipeline communicates with a buffer tank; heating the furnace startup materials to be in a molten state to form a furnace startup molten pool, wherein the furnace startup materials are pig iron, or the mixed powder materials in step (1), when the furnace startup materials are made into the furnace startup molten pool, a temperature of the furnace startup molten pool is controlled to be greater than or equal to 1450° C., a volume of the furnace startup molten pool is 20-30% of a total volume of the reducing furnace, when the furnace startup materials are the pig iron, the furnace startup materials are heated in an induced heating manner, when the furnace startup materials are the mixed powder materials, the furnace startup materials are heated in a manner that oxidizing combustibles are blown into the reducing furnace through the air inlet channel, the oxidizing combustibles are a mixture of pulverized coal and oxygen, or a mixture of natural gas and oxygen, a mass ratio of C elements to O elements in the oxidizing combustibles is 3:4-8, an outlet end of the feed pipe is located near the shaft rod, when a vortex is formed in a high-temperature molten pool in step (4), the mixed powder materials entering the reducing furnace fall into a center of the vortex, and at this time, the outlet end of the feed pipe is located above the vortex;
(3) lowering the stirring paddle into the furnace startup molten pool through the lifting device, starting the stirring device to stir the furnace startup molten pool, adjusting a position of the stirring paddle through the lifting device, controlling a vertical distance between the stirring paddle and a liquid level of the furnace startup molten pool to be ⅓-½ of a height of the furnace startup molten pool, at the same time, enabling the continuous feeding system to continuously convey the mixed powder materials into the reducing furnace through the feed pipe, and blowing oxidizing combustibles into the reducing furnace through the air inlet channel to heat the mixed powder materials in the reducing furnace, wherein the oxidizing combustibles are the mixture of the pulverized coal and the oxygen, or the mixture of the natural gas and the oxygen, the mixed powder materials are heated to melt in the reducing furnace, the molten mixed powder materials and the furnace startup molten pool form the high-temperature molten pool together, at the same time, the mixed powder materials are subjected to a reduction reaction to generate molten iron and reduced molten slag, and an introduction quantity of the oxidizing combustibles is determined based on a standard of controlling a temperature of the high-temperature molten pool to be greater than or equal to 1450° C.;
(4) under an action of a stirring centrifugal force and a coupling action of a gravity difference between the molten iron and the reduced molten slag, enabling the molten iron and the reduced molten slag to be separated quickly to form a molten slag layer in an upper part of the high-temperature molten pool and a molten iron layer in a lower part of the high-temperature molten pool, enabling the molten iron of the molten iron layer to enter the buffer tank from the iron notch through the siphon pipeline, along with an increase of a liquid level height of the high-temperature molten pool, when the molten iron is discharged out of an outlet of the buffer tank, adjusting the position of the stirring paddle through the lifting device, raising the stirring paddle into the molten slag layer, and performing vortex stirring on the molten slag layer through the stirring paddle so that the vortex is formed in the molten slag layer; and
(5) adjusting a stirring speed of the stirring paddle and a conveying quantity of the mixed powder materials so that the molten iron is continuously and stably discharged, and at this time, a liquid level of the molten iron layer remains unchanged; when an upper edge of the vortex in the molten slag layer is located at the molten slag overflow opening, discharging the reduced molten slag through the molten slag overflow opening; adjusting the position of the stirring paddle through the lifting device, so that a vertical distance between the stirring paddle and the liquid level of the molten iron layer is ⅓-½ of a height of the molten iron layer; and adjusting the stirring speed and the conveying quantity of the mixed powder materials, so that the molten iron is continuously discharged out of the outlet of the buffer tank and the reduced molten slag is continuously discharged out of the molten slag overflow opening.
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